SA Jarts

a jart is born

2011-08-24T15:13:00.007+02:00

After polishing the mould and applying the PVA release agent, I laid up 3 layers of 195gsm glass.

This produces a 225g fuse that is very strong. Here is the first one out, a little porky at 300g, number 2 was the winner at 225g, and they have been consistently this weight since then.

I skipped a bit of picture taking, and ended up here with little to no pictures.

Paint trim and servos to go in and then it's ready to fly.

The moulding process

2011-08-24T14:48:00.011+02:00

Here is the moulding process I used.

	After cutting out the shape of the plug into some chip board, I waxed the plug and applied PVA again. I then filled in the seam line with an epoxy/cabosil mixture from a plastic bag, kind of like an icing bag arrangement. Once cured the plug was removed and the seam sanded flat. This creates a fantastic seam.
	A closeup of the seam, see, no gap :)
	First layer of tooling coat on. Each coat is light and must not fillet the corners
	1 Layer 160gsm glass, 6 layers 400gsm Biaxial glass and then another layer of 160gsm glass, corners were filleted with carbon tow, should have used glass tow, but it was a pain to get so I just used carbon since I had it already.
	Mould just opened after second side was done. Needs a little cleanup(bit of paint came off the plug and stuck to the mould, quick scrape with a plastic scraper got rid of it without damaging the mould surface), but otherwise pretty nice surface

So it starts

2011-08-24T14:25:00.011+02:00

After reading much about the Jart, I purchased the plans for Reed and got going.

	I decided to use a high density polyester foam for the plug, The shaping was all done with a razor saw and sandpaper. This stuff sands very nicely, but what a mess!
	Basic shaping done.
	Fin Shaped and epoxied on. Starting to look the part now
	First Layer of 160gsm glass on the plug
	All sanded down and looking pointy
	Canopy mould being laid up. The plug was polished 8 times with Ram wax and them buffed out. Then a layer of PVA release agent was applied with a sponge.

The New 70" AFR JART - News from Reed

2010-06-21T07:53:00.000+02:00

Folks, I gotta tell you, I'm so happy with this thing. It's been a challenge, it's even been a little scary, but we have finally given birth to the new 70" ARF composite version of the JART design. Have a look at the YouTube channel, or just go to JARTWorld and check some of the latest posts to see video of the process and to watch the prototype fly on a mellow day out at the coast.

Use the PayPal buttons below to purchase your kit (or go to the Kits page on the website). You can use a credit card or your PayPal account, either will work. Production kits will be arriving here in a few days and I will begin inspecting and shipping immediately.

So this is how it goes: you hear that people want a rudder and flaps and a bigger version of the design and you say, "uh, ok!". To be honest I never needed all of that, I designed the plane as it was because it was all about me, me, me and I only wanted a simple plane that would fit in my car. Besides, I had to build them myself and didn't want to spend the extra time and money to fit flaps and rudder.

But here we are, 6 years later, and I find myself standing on a ridge, holding a 70" molded version of the plane with all of these bits and pieces wagging around, up down left right and all over. Just after launch I can already feel the size of the thing. Obviously I'm very familiar with the 56" wingspan, so having those big wings driving through the air is fascinating. At 72 ounces (yours should be lighter by 6 ounces or so) I'm surprised that the plane flies almost exactly like a 45 ounce standard-size JART, though I shouldn't have been. The extra size has a more than proportional affect on the airframe's efficiency so the numbers and the experience do match in this case.

For the first few minutes I flew with aileron and elevator only, just to get a feel for the handling characteristics. I certainly enjoyed it, and all of the maneuvers in the "teaser" video are with that setup. After a few minutes I decided to add flaps to the aileron movement and suddenly the plane felt more like a standard-size JART - very crisp and decisive in lateral control and overall very tight and neutral.

Then came the biggest surprise of all: the rudder. Honestly, I only added this to the design because a lot of people seemed to want it. For a 56" version I still wouldn't bother, but for this 70" version I thought the rudder might come in handy for inland "slermal" conditions where the pilot ranges out and looks for bubbles of lift away from the ridge and could use a flatter turn. It was a shock to me, though, when I pulled some rudder in on a racing turn and the plane came leaping out of the corner with unexpected energy. What I thought would be a fairly ineffective control surface is actually a very useful tool for keeping the nose straight through the turns and creating a "grippy" feeling, especially coming back from the downwind leg.

Landing this thing is just a breeze, especially if you already know how to land with flaps and/or crow. Once I got the elevator compensation figured out, those big flaps just bring the plane down to a crawl and you can land it on a dime in reasonable conditions. Being new to the flaps game it has taken me a few flights to get it dialed in, but I have a good technique now where I set the plane up behind the ridge and then pull in aileron reflex to kill some energy. Once the plane begins to settle down toward the LZ I pull the flaps in also and pilot the plane down to about waist-high where I pull the flaps out and let the plane sit right down. I missed a bunch of landings trying to learn this method and the poor plane took a lot of abuse dealing with my learning curve. But despite all of the bashing about, I never broke anything and was able to launch immediately every time - she's tough.

There will be many more flights and I'll post my impressions as we go. Can't wait to get her out to one of our DS spots to rev her up on the dark side!

Thanks

I just want to take a moment to send a special thanks out to all of you who trusted me enough to send advance payment for your JART-M70 kit. You have helped me more than you know and you have made it possible for many others to fly this cool plane. You may not have meant to be so helpful and beneficent, but you were, and I deeply appreciate it. As I've said before, there is blood money in this endeavor and that can be a scary thing, especially when things don't go exactly as planned. Now, however, we are finally enjoying what we have all worked to see.

As always, a thousand thanks to all JARTists!

EPP mini Jart

2010-01-04T18:56:00.004+02:00

The Jart was maidened on Friday at Tamatieberg, Volksrust. It fly beautifully and for sure a keeper. It was instantly my favourite model. At 600g I was not sure if it would go in the light lift, but it climbed out and after some trimming was zooming up and down the slope face. It is not as slippery as I thought it would be and actually can land slower than I envisaged. With more wind I will add ballast.

I resized it to a 1.2m wingspan to fit easily in my cars boot. I cut the wings and fuz on my CNC from EPP. She looks very sexy Hey!

Pity the weather turned to mist and rain on Saturday , so I will have to go back soon.

Cheers

Gert
TRMC Secunda

Double Trouble

2009-11-22T11:33:00.004+02:00

The terrible twins are finally complete with thanks to all that contributed to the build. WELL DONE !!!
We are ready to take on the slopes of Hermanus next week. So watch out!

Sean on the left and myself on the SW Slipper face.

Flying Jarts in formation is not for the faint hearted

Filming Jarts ai'nt easy eather!

Give the file a moment & enjoy!

Baptism of fire

2009-11-18T12:37:00.005+02:00

Yesterday, with the South Westerly wind blowing 80km/h, Sean and I decided to give the Red Bull Jart her baptism of fire and went up the Lady Slipper. The site is located on the highest peak in our area and generally works best on a South Westerly or North Easterly wind. The height above sea level usually provides ample lift.
80km/h winds are overkill to say the least!

One of a few landing attempts

Typical Jart Profile

Sean surprised that the plane was still in one piece

Wind speed indicator

Holding the camera in the wind was almost as bad as flying the plane, so look past the shakes!

JART-70 short kit announcement

2009-11-11T12:14:00.005+02:00

JART-70 Short Kits Are Here!
The photo above has two cool subjects in it - one is Jeff Fukushima, legendary slope designer (Vortech Models) and his finished version of the new JART-70.I asked Jeff to help me create a new mold for a 70" JART kit. He did not disappoint. After a few weeks of craftsmanship Jeff had produced a big, gorgeous plug for this larger version. Now, he's been kind enough to crack a few fuses out of that mold and make them available to us mere mortals.Six of these fuselages are currently available, along with a set of beautiful, CNC-cut, spiderfoam wing and stab cores. The cost for this short kit is $190, plus shipping, so if you're interested just send me an email at reed@jartworld.com and I'll work out the total amount for you.Don't hesitate on these! Jeff says he'll make more when he has a chance, but there is no guarantee when that will be. This is pure love-of-the-craft, out-of-the-home-shop stuff - ain't nothin' mass-produced about these babies!

JART-LX news
Folks, we are sooooo close I can almost taste it. My push is to have kits ready for you by mid-December. But here's the biggest news - I've decided to go all out for this one! The new kit will have carbon wings, a beefy, rectangular carbon joiner, generous flaps, and even a rudder option. The design was always meant to be versatile, but now it will be hard to beat - fast, aerobatic and able to float down for a landing. Best of all the price will still be very reasonable. In fact, I'm going to try to keep it down around $300, plus shipping.Just to whet your appetite, I'm including an image of the CAD-generated file that will be used to tool this new beauty...

JART-EPP Kits Available
We have a few EPP kits available for those who like a bouncier plane. Same great quality you're used to with these kits: pre-shaped fuselage, clean-cut wings, carefully chosen wood, full hardware package, build instruction CD...about all you need is glue and covering!Kits are $150 plus shipping. Email me at reed@jartworld.com and I'll give you a total for your PayPal payment, personal check or money order.
Here's a shot of the kit and some finished versions...
Thanks
It hasn't always been easy, but knowing that people are out there who know and care about the JART always keeps me moving forward, trying new things, hoping to find ways to help folks enjoy the sport of RC soaring.

So thanks for keeping me in the game!

Reed

JARTWorldSan Francisco, Californiahttp://rs6.net/tn.jsp?et=1102819695922&s=57&e=001Bm__nJPVDwidbMZGWOVJezMFQbQVofO_WeVVYOpj6eB8mWGXTj2SUNU_PjrEGp7EqM1TB-VnImwF2xLTJjTdFCtXN4cbpdEIEHvkden6eNaItu3LF5toCSt1xflIZvLVLKk1Vao7cCcN7-PP5iRXsQ==contact Reed

Maitlands

2009-10-26T12:09:00.003+02:00

These photos show our slope location at Maitlands, Port Elizabeth, South Africa

1. This is an overhead shot of the Maitlands slope that we share with the para-gliders

2. This shot is slightly above and along

3. A Google location for Maitlands

Red Bull Maiden

2009-10-19T12:13:00.005+02:00

1. The Jart in her new party dress

2. Looking good

3. Looking mean and fast

4. Belly shot

5. Sean and Vic giggling uncontrollably!

Friday arrived with a moderate South Westerly wind at about 20 Km/h ( note the lack of white horses in the background!) We decided to toss her anyway and managed to trim her up in flight. The aileron throws need to be readjusted as the roll rate was nowhere near the old Jart. Wind strength did not help much either....

The main thing is she flew, and we'll put her through her paces soon!

Red Bull Jart

2009-10-16T08:34:00.005+02:00

I know, I know....... just another Red Bull plane that" gives you wings"!
So what, I enjoyed building it and the stickers were lying around. The process also taught me the art of spraying and masking! I must have sprayed the three colours six times and taken it down as many. We are just waiting for a strong south westerly!
The plane weighs in at 1150 grams fully loaded and is perfectly balanced. I have given Alain my old one as it has had a tough life. It's been crashed and flown hard and still flies beautifully!
I must just ensure this one lasts so that we can take it along to Hermanus in November!
As Daron would say, YOU HAVE TO HAVE ONE OF THESE IN YOUR QUIVER"!

2009-09-15T22:08:00.002+02:00

2009-09-15T22:01:00.001+02:00

2009-09-15T21:55:00.001+02:00

Do I thank him or curse him?

2009-09-15T20:49:00.003+02:00

Hi there all. Just joined the blog, thanx Evan. Thanx to Johann, or should I curse him? We went flying today, the conditions were SSW about 35km/h....On our "little" slope, that means.....PERFECT CONDITIONS!! Note the white horses in the background. I flew Johanns Jart...WOW!!...TWO WORDS.......ROLL RATE!!!!Ok, so now I have to get started on mine.

News From Reed at Jart World

2009-07-07T11:05:00.005+02:00

JART-LT/LX Moulded Wings!

It's been a long road, but we finally have some decent moulded wings for you LT owners. These are the same wings that will come with the new, all-moulded JART-LX kits.

These wings fit perfectly to your LT fuselage, allowing you to plug-and-play with very little fiddling - just fit your servos and control bits and off you go.

The economy as it is, I'm forced to make smaller orders and sell them out rather than hold a bunch of stuff in inventory. So right now I have 4 white sets of moulded wings left from the original batch. They're all white and go for $145 plus shipping.

Email me at reed@jartworld.com for shipping costs and order details.

Also, we've had a few of the new JART-LX kits come in and they've already sold out. These will come in red, yellow, and white. Please email me your colour preference so I can get an idea of how many to order in the next batch.

Cheers,Reed

Johann & Daron

2009-04-14T13:05:00.003+02:00

Finally we have a Jart the way it is supposed to be...... flown on the slope!
The wind was 25-30km South west on Monday and perfect for the Maitlands slope. The slope is not very high and therefore does not generate great lift, but if it blows directly up the face, one gets clean air. Daron was very apprehensive but maintained that the Jart wanted to fly. It is not the easiest plane to launch as there is very little holding space below the wing. I launched it with two hands and with very little adjustment on the elevator, it flew straight out. The plane flies beautifully!
Thanks to everyone for their support and useful advice.

Daron's yellow and black Jart

After getting the plane trimmed out, Daron was having such fun that I decided to join him and launched my more sedate Salto...... It has to be sods law, Five minutes later we had a head on in mid air... What are the chances?

WELL WE ARE BACK IN THE WORKSHOP!

Besides all the mishaps, we've had great fun and the plane really flies beautifully! We'll get the other one ready for it's trails. Lets hope it goes home.

It has been worth the time and trouble and we've learnt so much!

2009-03-03T09:09:00.004+02:00

Finally we have reached the stage where we can launch and test fly our prototype!
If you look closely you'll see the blunted end of the Jart with the unforgivable prop fixed to the front! Vic being a purist was much distressed but agreed to come to the field and watch Daron do his thing.

Daron : the elected test pilot

I canabalised my hotliner, (composite Baudis Zoom) and removed the Axi motor and planetary gearbox. We knew the arangement would work as both planes have a similar all up flying weight of 1300g and fitted a 14x10 folding prop on a 28mm spinner. The nose had to be reshaped from it's oval profile to accommodate the spinner.

The actual launch was pretty uneventful except for a twitchy left and right wiggle as Daron adjusted his fingers on the controls. The motor arangement can take the plane up vertically and by the time Daron cut back the throttle back, the Jart was a tiny speck in the sky.

That was when the problems began......

Daron failed to level out before cutting back and the plane entered a stall and seemed to drop a wing. Besides being so high up our colour scheme did not help with the oriontation and the plane never recovered from the spin. Hard to believe with all that height to play with. We have come to the conclusion that it was all pilot error!

The plane hit the ground nose first on a hard surface. Th amazing thing is that there is hardly anything wrong with the plane. The motor gearbox, prop and elevator servo are buggered, but for the rest the plane is still intact with marginal damage to the wings and fuse.

It was rather distressing, but we'll try again! Just waiting for parts.

Vic's pulling his nose at the thought of a prop!

At this stage the going has not been to good with two flights and two crashes. The first was Vic's balsa prototype in a 100km/h wind and Daron's disoriontation....

Third time lucky!

Johann, Daron & Vic

2009-02-16T08:49:00.007+02:00

Finally some progress!
When you receive e-mails stating " I keep looking on the JART-SA blog hoping to see someones Jart progress but nada, niks, and zero." you know the pressure is mounting.
Well to recap, we shaped and glassed plug number 2. There was some debate as to the finishing coats and unfortunately we applied some epoxy coating that ended in disaster. The full curing time was 10 days which conveniently fell over the Christmas holidays.

Plug number 2

Epoxy coating gone wrong

Gel coat and epoxy coating in a marriage gone wrong

Not quite the best spray booth.

Dejavoux

Plug set in the splitter board

The plug still stuck in the mould, but salvaged

De lamination of the K2, probably due to the adhesion to the

epoxy finishing coat remaining in places after sanding.

And finally! The mould had to be cleaned off, but

came out beautifully

4mm studs used as locating lugs

Layup complete and curing

Bench flying!!!!

The fuse seam joints have been a bit of a headache. On this one we tried a wet joint as we have been to scared to cut the mould to enable us to work on the seams. whilst the joint is sound, the overlaps have folded in places.

On the following fuse, we will try smaller overlaps and two pairs of hands!

Thanks for all the continued advice and support.

Finishing for first class results

2008-12-02T14:49:00.007+02:00

Hi There,

With Johann currently tackling his second attempt at a moldable plug I thought I would post some pictures of my method , which is by no means the only way of doing things, but works for me.

Although 2k paint sometimes sticks in the molding of the plug , this is most likely due to problems with the release agent and not the paint. B.T.W. this type of paint 2k has been very successfully used in all the team built Shongololo's of Evans building groups, and is still my favorite when spraying a plug and polishing it, or the mold surfaces of a hollow molded glider.

After the blue foam plug is nicely sanded to shape and layed up ,with in this case 3 x 163 gr cloth layers, I sand it smooth with 180grit paper, especially glass cloth join lines.

Then the whole plug is layed up with a layer of 104 or 86gram fine cloth, I add a small amount of micro balloons to this resin layup , this aids in filling pinholes. You will see that although the foam is blue the resin/balloons make it look whiteish.

The plug is now wet sanded with 220grit , the surface becomes smoother and any imperfections are filled and repaired.

The product shown left is an epoxy based finishing resin , it is a two part and seals the surface well and is easy to sand.

Its available in most good hobby shops.

I make a mix of this and add microballoons , this finishing layer is screeded onto the plug and gives a high build smooth coat , as you can see, this is then waterpapered with 480 grit wet and a few drops of dishwashing liquid in the water.

This surface seals the foam from any solvents and provides a good surface onto which you can spray.

My larger plugs were finished in a similar way

but instead of the ZAP finishing resin I finish with a 2 part polyester spray filler (but care is needed as this stuff eats the foam , if it's exposed.)

I trust this may be of help to modellers out there.

Note 2K paint contains ISOCYANATE (a Cyanide derivative) in the harderner which is bad for you, so always wear a respirator and protective clothing.

Happy building.

2008-12-01T16:39:00.003+02:00

Thanks for all the support and guidance especially from Evan and Mike. It seems like this has turned into a bit of a process....
I have not had a chance to respond to your e-mails, but I'll get there!
Evan, we managed to get the coating that you recommended for the plug. We tried several places and between only selling the paint in 5l tins at R1600.00 we finally managed to get a litre. I hope it is the correct one! the trade name is SIGMAGUARD HS which is described as a two component high solids polyamine cured epoxy coating and comes in a green grey colour.
The curing times seem to be a bit of an issue as it is described as 20 hours min between coats and 10 days for final cure.....
That means we will only cast our moulds in January......
Vic has given up on us and has proceeded to build a fuse out of balsa. (He has the time and it's his preferred building technique anyway) It may be a blessing in disguise as we can use the prototype to iron out all the gremlins. We'll post some pictures as he progresses.

Meanwhile Daron and I can dream about our future composite plane and colour schemes whilst we wait!

Mmmmm Daron likes black and yellow....

2008-11-25T14:00:00.006+02:00

Hi there Mike, Evan & Vic

Thanks for the support that you have provided so far. I must say that some things you mentioned are so logical that I can't believe we never thought it thru such as casting the otherside of the mould without removing the Plug.

Plug number 2

Anyway, The new plug has been shaped and layered up with one 50g cloth and one 200g layer. We have re sanded and got back to shape with minor blemishes.
Should we put on another layer of glass, as I noticed the previous plug developed small pressure indentations during the final sanding and polishing phase?

Our wings are progressing well with some help from Vic Oxley who is an old hand at constructing built up wings. He has kindly undertaken to construct the wings for us. We would love to try bagging, but without a vacuum pump and the suitable knowledge, we will leave this process in abeyance for the time being.
Vic has been building and flying in our area for the last thirty years or so!

Vic Oxley hard at work in his workshop

The foam cores have been cut and he has elected to build a balsa covered wing which poses a bit of head scratching as regards the fixing of the wing to the body.

The thought has been to cut the"canopy" opening down to the bottom edge below the wing so that the wing can be bolted down to the lower section of the fuse and the enlarged canopy will be shaped to the top of the wing profile. It may help to have a removable wing and we are looking to put a centrally placed servo for the ailerons....
We're getting ahead of ourselves!

Thanks for all your positive comments and support.
Kind regards
Johann & Daron

Johann & Daron

2008-11-17T14:34:00.009+02:00

It all starts somewhere......
It was about messing around on the Internet, browsing to see what planes were around, when we happened to come across the Jart web site. After looking around the local builders and seeing Adrian's build thread it made us believe we too could build this plane..... how hard could it be?
The fact that neither of us had built a scratch plane (balsa or glass), other than damage repair, did not deter us.
We sourced some Iso board and shaped the plug... so far so good
Then read up on all the epoxy and paint coating specs.....
glassed and painted....
( not without mishaps)
And we were the proud parents of a Plug!!!!
All shiny and smooth.
This was then laid up as described by Evan and others

My daughters got so exited when they saw their Dad busy with blue paint that they volunteered to help....

This only lasted for 5 minutes until they discovered that it was all gooey and did not come off.

The splitter board came off with no problem.

And......

It STUCK.....

I'm trying to get over it!

I must admit it's hard not to just give up.

I'll give it a day or so to come to terms with my short comings...

I suppose it's part of the learning curve and life's rich tapestry of experience.

We'll post some more pictues of our next build....

Progress - down the twisty road now!!

2008-11-07T14:17:00.006+02:00

Wings out of the bag, root ribs had to be ditched as I forgot about trimming to the fuselage angle before adding the ribs....

I used a rubber polising wheel on the dremel to dig out the foam. You can go right up against the skin without damaging it and it eats up the foam no problem.

Then I mixed a strong cotton flock mixture (with no cabosil to allow it to run) and

poured it in the gap. The leading edge was dug out to about 50mm to seat the alignment peg - a 5mm diameter length of music wire fitted with an alignment tool - just an old printed circuit board with two holes drilled through it.

A bit of paint, some articulation and a new twf pnf toy is born!!

Articulation

Side on -

Full turn!

Look Ma, no elevator- no aileron ................ no Brakes!!

Just two servo's to fit (DS8711's with plenty amandla) and a ledge for the canopy and were are done.

ps - anyone else done a twf Jart in SA?

Fuz

2008-11-06T14:12:00.002+02:00

No I have'nt just been sitting around but trawling the internet for acticles and advice on fibreglassing techniques. Also been shaping the fuselage and finally got enough confidence to do my first fibreglass project. All done now and expoxied, in the process of micro balloons and sanding to get to some resemblance of the finishes I see produced by the Jarters. I think the fuselage is a little plumper than it should be as I did'nt allow for the thickness of the glass etc. Looks cool though. Pic's to follow. Also got a wing and stab from Adrian so that should shorten the final programme.

Wings!

2008-09-30T16:26:00.005+02:00

Some progress with the wings at last.

I 3M77éd the aramid leading edge cloth on again, this time with copious 3M. Added a vertical grain balsa subrib at the end of the joiner tube to spread the load out to the skins.

Then I added a strip of peel ply to the mylar leading edge with double sided tape making sure the peel ply extends +- 25mm past the mylar leading edge. This way, once you put a strip of bias cut glass onto the aramid and place the mylar just short of the leading edge the peel ply gives a beautifully "pre-finished"leading edge. (As per Mark Stockton's

Tabooish build thread at http://www.rcgroups.com/forums/showthread.php?t=634176 )

Well, no more excuses, the layup on this one is all glass, 1 of 25g veil cloth, 2 off 163g and a half span strip of 163g all on the bias.

Much anticipation later, burnt out the old switch on the vacuum pump, replaced on the fly and out came the wings, sheer magic, biggest bagging job yet, check the leading edge! (all untrimmed and not yet sanded at all)

It Flies what else?

2008-08-26T16:56:00.004+02:00

Well finally the second Jart had its maiden flight, this last weekend at Volksrust, a group of us went down for the weekend. On saterday afternoon the wind had swung easterly and really picked up so we moved to the eastern point and I decided to give it a go.

This Jart is light it weighs just under 1kg and is fitted with two nice MG digital no name brand servo,s which I am trying for the first time.

The launch was uneventfull and she only needed a few clicks of up, this one is a little faster than my first one which has an MH32 airfoil . I also programmed in some flapperon which helps slow down for landings.

Anyway the first flight was a blast and on the sunday I tried a second flight in lighter air which resulted in a nasty tipstall and flick , you need to keep the speed up on these gliders, so due to the lack of good lift I safely landed.

I guess it's on to planning Jart number three .

Cheers

Mike

Ps I highly recommend you get yourself one they fly great.

Joiner success!

2008-07-21T16:06:00.003+02:00

Just opened up the second carbon joiner and it's much better!

The tube is 12,5mm id and that takes 159 tows to fill completely so this time I cut 100 which is just over 60%. I also had an extra 20 in case this was too loose after coating with resin. As it turned out I used the extra 20 so my carbon content is just over 75%. It took all my weight on the joiner with the wire in the vice to get the tows through - very slowly!

My method for wetting out was to keep the wire hook in place and place the tows on a plastic sheeting covered bench, pour out about 80% of the resin and roll it with a ribbed roller. Turn over and add the rest of the resin and roll and roll and roll....

Evan just mentioned to me today that he dunks all of the carbon tows into the resin container (whilst keeping the looped end on the wire pull through) and squeezes out the excess which sounds much quicker!

New joiner is 65g, old one was 57 g, better fit and finish plus more strength!

On to the wings next time.

Time to do it again!

2008-07-02T22:16:00.003+02:00

In the time honoured Jart tradition of learning new and fun stuff - sometimes you have to do it again!

The aluminium tube used to make the carbon wing joiner rod took a lot longer to dissolve in caustic soda than I had thought. Thanks Mike for the suggestion to put Dremel grooves on each side almost right though - even then it took two days to get through the grooves!

The calculation I used was 40% carbon 60% resin (very pessimistic) and when wet out it was way too easy to pull through the tube. I increased the carbon to 50% by area and it was much tighter so I left it at that.

Clearly not quite enough carbon as you can see - next time it's 60% carbon and if that isn't a really tight fit then add a bit more!

Just to make it a full house the motor I installed to power my vacuum pump had a faulty nameplate. It says it's S1 duty rated, i.e. continuous running but this was incorrect leading to massive heat build up and bad smells! It was set to run for half an hour then wait an hour as the vacuum regulator switch is giving problems. (It was not pressing foam but a wing mould so the very high vacuum was ok).

Oh well, the wing is next, just after the vacuum pump is re-built and a quick trip to the Berg next week!

Anyone know where to get a proper vacuum switch – Festo’s one is nearly R1000 while Joewoodworker.com’s sells one for only $25 but won’t ship to South Africa!?

Hot Jart

2008-06-30T09:26:00.005+02:00

Well I got a chance to do a little final decorating , this is often determined ,by the colours I am spraying , as I line up a few plane projects for spraying at the same time .

Yesterday I mixed up some bright red 2k to finish off the yellow Jart and also spray up some mylars for a thermal ship which has been sidelined for some time.

First off I decided on a pattern and started masking with some plastic tape which gives nice sharp lines.

Next I masked and covered the entire plane , if there is any small overspray, this can be polished off later.

I layed down 2 x coats of 2k red and let it flash off, which is quick with the fast harderner.

As soon as its touch dry I remove the masking , carefully lifting the plastic tape. It all came out

rather well and with the red paint still pliable there is no chance of flaking or chipping which happens if you de-mask after a couple of days cure.

Final touch a JART sticker and now I will cut the ailerons and elevator and start the plumbing.

Wing progress

2008-06-23T16:25:00.004+02:00

Bit slow on the wing progress, hope that I don't have the same problem with the paint that Evan had (see earlier posts by Evan re Eskom induced delays) as my stab and wing mylars were painted at the same time!

The joiner tube is a bit large so it needed filing down. The reason for the size is that the carbon joiner needs a fair amount of carbon in it and the aluminium tube is quite thick walled.

This is the joiner tube area after the first application of epoxy-cabosil-cotton flocks-micro balloon mixture. Some voids still need filling.

The aluminium tube with its carbon tows ready for insertion after resin application.

I am using the standard Reed specified S6062 at 7,95% thickness. For the stab I used an aramid leading edge but this was a bit tricky as I did it at the same time as the bagging! Not as per the experts and it was made even trickier because I only 3M77éd the stab halves together. Epoxy dissolves the bond after a short time...

For the wings Í discussed the layup with Craig (thanks!) and also used Joe Wurts' spreadsheet (http://www.charlesriverrc.org/artic...vacbaglayup.htm) which gives some comfort that things won't just break apart in mid air (as opposed to the more common/acceptable ground breakage!).

All the glass for the wings has been cut and is just waiting for the final sanding of the joiner tube areas while I debate whether to put on an aramid leading edge....

Started!

2008-06-20T18:50:00.003+02:00

Finally, after ages of planning, reading and thinking I've just got a fresh Jart stab out of the bag, very chuffed as it's my second bagging attempt and the wow factor when you open a "To Dad, From Dad" present inside the bag is superb!

The leading edge and trailing edges just need trimming now.

Craig Goodrum and Evan Shaw's composite courses at AMT made it go pretty easy so it's on to the wings which came out great (thanks Mike for the template tip! - use thick Formica and a home-made feather cut).

The wings are going to be two piece for ease of transport. I discussed the wing joiner rod with Craig and I'm going to use the tows-in-a-disappearing-aluminium-tube idea. Pictures to follow as it's being done.

Thanks again Mike for your help and Reed for the generosity with the free plans for this beautiful plane!

Vic

About to start

2008-06-19T10:26:00.003+02:00

Got the plan from Reed awhile ago and been threatening to start. Finally had chat to Adrian and see that I have a lot to learn and a long way to go. Anyway have made the decision to plunge headlong into this build. Going to get pdf printed and buy some foam and get started. (My son is on 6 weeks holidays and if I get going maybe I can entice him to get his hands dirty)

Here goes.

Jart 3 Canopy

2008-06-02T09:03:00.005+02:00

Some good progress this last weekend on this build, I managed to join together all the big pieces,and it is now a Jart.

I fill the join lines and the wing shoulder gusset with micro balloons and some cloth on the wing and tailplane join lines.

After carefully cutting out the canopy, I make two small pieces in the mould, I dont spray the mould , the yellow in this case is pigment in the resin, these are the rough pieces on the wing nearest.

These pieces o about 4 layers of cloth are cut so that they fit on the inside of the fuselage and being flexable and more or less the right contour,
are easy to position and epoxy in place.

In this photo the lip is epoxied in place and the pegs hold two pieces of ply , which will be drilled to accept two small self tapping screws which hold the canopy on.

In the final picture the tear drop canopy has been sprayed black and the rest final coats of yellow.

Next I need to cut out the ailerons and elevator and wire up the servos.

At the moment it weighs 740 grams and feels lightish but battery , radio gear and balancing will change all that.

Hope this one flies even better than the red one.

I have done a slightly different canopy shape, but still starting ahead of the leadind edge so that I can still fit in a fair battery pack and full size receiver in its protective foam.

Some stripes next to tell the top from the bottom , important when doing rolls as these things roll , at a rate nothing short of a frenzy.

Jart 3

2008-05-27T13:04:00.005+02:00

Nothing like practice, Jart 3 the white fuselage popped out the moulds no problem. If you build a glass model that you think you may want several of , its always a good idea to pull a mould, especially off a smaller model .If one crashes (does that ever happen to you) you can simply make another.

I am pleased ,I had made a mould , as my RED jart flies great so it is a well proven design. It also allows a fair amount of experimentation , with different lay-ups.

I am sure ,Glen from Durban will appreciate this as he is busy with his Jart using the lost foam technique, and the accompaning sanding and sanding.

PS. for the very sharp eyed, you will note I had in fact previously built a white fuselage so this is in fact Jart 4 , that one was traded to a licensed Jart Plan owner for 4 sheets of blue foam a fair swap I think.

JART no 2 and 3

2008-05-21T14:27:00.006+02:00

A little Jart building at last, I sprayed up my moulds a nice rich yellow some months ago and put them aside to finish other projects . Recent outings with my red Jart have really been fun so time to get cracking on number 2 Jart, you cant have to much of a good thing ,you know.

The fuselage came out nice and strong and is now ready to be cut for wings, tailplane and canopy.

The yellow wing is blue foam with 1 layer of 104 gr glass then a lengthways 100 gr UD carbon and finally a 163 gr glass at 45 degress, it all feels nice and stiff and now needs to be trimmed and cleaned up on the leading and trailing edges.

The current weight of these two parts is 680 grams , but it still needs assembly of a tailplane and radio gear. they fly great at about 1.2 to 1.5kg in a fair blow.

With several "white" model projects on the go I always keep my moulds waxed up , and if for some reason some mixed 2k is available I go ahead and spray any excess paint into the next mould , so white it is . These fuselages are also perfect for using up all those off cuts of glass , these I sort and store in seperate plastic bags by glass weight and shapes.

The third Jart out of the mould is going to be white , and I laid up some ud carbon cross ways
were the wing and taiplane bond onto the fuselage.
Some nice red and blue striping would make this an attractive colour scheme?
go build your own Jart.

Glen Jart progress

2008-05-16T09:46:00.007+02:00

I did tell you not to expect too much progress in the short term, but surprisingly, there has been a little.... Last Friday I was able to hand the "completed to this stage" fuselage over to Jacques for him to cut the wings,fin etc. Once this has been done, I will take the fuz back, blend in the wing fillets and fin, and prep for final spray of undercoat and colour. Did I mention that Jacques is planning to make his Jart a 2 piece removable wing option, so that transport to and from the slope is easier?

Again, many thanks to Mike May for his invaluable advice and motivation, especially during the epoxy and balloons/sanding stages.

Pictures of the project so far.....

Lots of carbon goodness for extra strength and vitalty.

Done at last - after lots of filling and sanding. Maybe my lack of glassing skills have something to do with it.

See what Mike Ma(y)de me do!

2008-04-09T09:16:00.004+02:00

Well, it all started with Adrian B in Cape Town being reluctant to part with a blemished Jart fuselage and then followed by the non appearance of Santa down my chimney in December 2007, so it was decided that there was only one thing left to do! Seeing as the mysteries of composite construction were being unravelled to this newbie via another project I had embarked on (also coutesy of Mike May and the Sungazer event), I decided that, with advice from Mike only being a phone call away, that I would try my hand at this Jart thing. Please, dont expect miracles and hope to see this thing fly before December this year (2008), as I am a slow builder with LOTS of distractions. I checked the other day - I received my plans from Reed in March 2006! (does that tell you something).

By the way, this plane is being built for my flying buddy and neighbour Jacques, who will be assisting along the way.

Here is the progress (or lack of) so far....

Fuselage shaped out of isoboard foam, with first layer of very thin glass cloth added. Dont ask me details such as weight of glass cloth etc because I dont have a clue - I just do what Mike tells me to.....

More to follow in the coming months.

Mikes Jarts No 2,3

2008-02-08T13:25:00.002+02:00

With the local gliding scene moving to the thermal competetions there has been a break in Jart activity.

The sucess of my red Jart has prompted me to build 2 more, my son has his eye on one , so I am glad I bothered to make a mould.

I spray the moulds and , during other layup projects I use the off cut glass cloth , that comes from wing layups were the roll is cut at 45 degrees and there are big off cuts. I then build Jart and other fuselages.

Will post progress of these two as I go

later.

Mike's Jart

2008-01-07T09:01:00.000+02:00

Well back from Volksrust , and maidened the JART successfully, a group of us went down for 4 days and generally the wind seemed to really pick up in the afternoons.
The first day the wind was ok for Zaggi flying but just not enough for the JART.
Thursday produced better conditions on the south slope so I decided to give the Jart a go.
It went straight out and only needed two clicks of up trim, left and right was spot on.

The video shows the moment of truth , unfortunately the wind dropped after a few minutes, and the jart just could not maintain altitude , it landed about 20 mtrs down the slope but was unharmed.

In the afternoon later in the day the wind swung easterly and we flew the eastern point , great lift and the Jart was, in its element it does all the things everyone raves about , its smooth flying when it has a some speed is most impressive , it does not like to be slowed down . The landing was down wind in a bit of a rotor and it cartwheeled on landing , slitting the nose open. That evening I rejoined the split which was on the join line with some cloth and it was good to go.

Saterday saw us back on the Northwest slope this time and at about 14-00 hours the air looked Jartish ready, this flight went off all wobbly until I realised I had the max rate set on my dual rate switch for ailerons a quick flick and she settled down nicely.

This flight was excellent and I pushed the Jart a little more with rolls and loops, what made it really special was that for the first time Blake my son stood next to me flying his Zaggi totally unaided so he has pretty much gone solo. The landing was fast and smooth with only a little flare, right at the end to prevent the nose(pointy in case you havent noticed)from spiking the ground.....

conclusion its a lovely design looks great in the air and is a perfornance machine ,well worth building one.

PS I have already started no 2. and have completed the fuselage already,I will post a mini build thread as I go , not so much the construction but the enhancements to the red no 1.

cheers for now.

Jart's Maiden flights at Volksrust -Trevor & co.

2007-12-31T06:00:00.002+02:00

Kobus, Wesley and Trevor, went down to Volksrust just after Christmas to maiden their Jarts. I was there and took a few photos of the action. Very impressive when a scratch built model is launched and flies beautifully straight off the building board. Not to mention how great these models look in the air and how well they fly. And the paint jobs on theses three Jarts are very striking. Well done to them all on a great project.

Both Trevor and Kobus flew their Jarts, but unfortunately Wesley's did not get to fly because of a problem with the ailerons movement. The photos below can tell the rest of the story.

Trevor's first with Kobus helping with the pre-flight checks and Lionel doing the launching.

Then it was Kobus' turn with Trevor lending a hand!

Joining the wings by Trevor & Co

2007-12-30T21:11:00.000+02:00

Hi Jarters

After crossing the hurdle of preparing the fuzz, it is now ready to add the wing joiner for the wings onto the fuzz.

We took the same size hollow carbon tube as we put in the wings, and aligned the wings up on the fuselage and inserted this tube across the fuselage. The wing joiner was made out of carbon toes pulled through an aluminium tube the same side as the carbon tube used in the wings. We used caustic soda to remove the aluminum from the rod.

Once we had aligned the wings, we found imperfections in our wing-lets and had to remould and form them all over.

After much sanding and finally getting the wings lined up with the fuzz, we needed to set the incidence on the wings and the stabilizer. Using the plan as a guide line,we used and incident meter to set everything up.

As we went along, things got easier, by the time we did the 3rd plane.

Once Kobus's Jart had been set, it was now time to mask off the stab and paint the fuzzes.

(At least some progress seemed to be taking place)

Finally we started the painting.

After struggling with Kobus's painting we finally had finished the three Jarts.

We now had to finish the cutting and making the hinges on the ailerons and stab.

We cut out on the bottom of the wings for the HS125mg wing servos and put the pushrod in for the HS85mg elevator survo mounted in the front of the fuzz. We checked out the CG and had to add 160G of lead to the nose and they are all ready to fly. All three Jarts weighed between 1.5kg and 1.55kg.

When the winds picked up at about 2pm on Friday at Volksrust we Maidened our Jarts.

I was amazed at how well they moved in the sky and only trimmed out the elevator about 2 clicks of up trim and she flew straight and fast. Kobus also added a little up trim when he flew the yellow Jart. After the two flights we discussed the performance of the two planes and came to a mutual agreement that they are great in the sky and all the hard work really was worth it.

We will maiden Wesley's next time and I am convinced that his (the blue Jart) will also fly great.

Evan has some photos of the Jart in action on the slope and said he will post them soon.(can't wait)
This has been a great project and we have enjoyed learning new ways of creating and building planes using carbon and fiberglass. We look forward to another project like this one.

Regards

Trevor, Kobus & Wsley

The Fuzz (cont) by Trevor and co

2007-12-30T19:07:00.000+02:00

Hi Jarters

The last time we spoke we were getting our fuzz's ready for undercoating and the removing of the foam, wow preparing the fuzz is a lot of hard work and sanding, but eventually got it right.

We sprayed the fuzz in mc primer, only once we had sprayed the primer on, did we realise how many holes and defects there really was, so we sprayed and patched and sprayed over and over......

I don't recommend that the wing-lets be put on while preparing the fuzz as we have, because getting everything straight and aligned is a mission. Doing this type of building for the first time really made it time consuming getting it all straight, but in the end after all that hard work we decided to cut them off of Kobus and Wesley's fuzzes.

Finally we got all the fuzzes sprayed and undercoated and decided to create the canopy now before opening up the fuzz and removing the foam from the inside.

To create our canopy, we were privileged to have Kobus in our team to make a plastic mould from one of his moulds from another plane.
We took this mould and polished the inside of the plastic and laid up some fibreglass and resin to create a canopy.

This canopy was our dummy canopy to cut out on the fuzzes.

Once we had tested and made sure that this canopy fitted snug on the fuzz, we then used the same mould and laid up 3 canopies with 2 layers carbon(96g cloth).

Once we had the canopies done,we put them on the fuzz in the correct position and drew a line around the canopy on the fuzz as our cut line.

Trevor's fuzz was the dummy run and the cut out was the same size as the canopy, but Kobus decided to cut his out smaller and allow his canopy to overlap the fuzz (This turned out to be the better option).

After removing the cut out it was time to clean out the fuzz with petrol. We were all looking forward to this because at this stage all our fuzzes were quite heavy.

To our amazement only about 30g, if that, was taken off the overall weight. It was now starting to take shape because we could start attaching the necessaries for the wings.

On our next postings we will follow up on joining the wings.

Regards
Trevor, Kobus & Wesley

All I want for Xmas is a RED HOT Jart.

2007-12-26T08:39:00.001+02:00

Well after not falling for the reindeer food that I set out for Santa on Christmas eve, I manage to contact the overworked guy to stop in on Boxing day before his long flight back north. He showed me his empty reindeer food bag (as you can see in the picture below).

However I quickly re-fueled it for him (hoping to score some brownie points) and hoping that he just might have one more Jart left amongst all his empty Christmas bags. But alas there was nothing.

There was one bag though, that looked quite full and rounded in the right places. He said that I can gladly keep this although it might not fly to well.

So I offered to look after it (hoping to score some more brownie points). He also gave me his Shotgun and some cartridges and said that I might need it in the process, as nobody is going to Hi Jack a Santa with a empty sledge on his way home.

Not wanting to disappoint the dear old fellow, I agreed to all his terms and conditions and soon he was on his Sledge and with afterburners glowing Red Hot (sounds familiar) he disappeared into late night sky. A happy fellow with his work done for the year.

Obviously I was disappointed at not getting my Jart for Xmas but I could not wait to see what he did given me for Christmas. So I rushed inside and this is what jumped out the bag!!!

Anyway, I am quite happy with this present. Don’t get any ideas guys. Remember the Shotgun!!!.

I will just have to compete my Jart in the New Year seeing as how Santa couldn't help!

Wishing all Jartists a Happy New Year.

Piet.

email from Julian Kent (aka minifly on RCGroups)

2007-12-24T06:09:00.000+02:00

Just to let you know, I think I was the first person to complete a Jart in SA. My Jart flew at Hermanus 2006, and despite its extreme nose-heaviness and me pulling the spoilerons a moment early, managed to get a decent shot at the spot landing. Aragon got some video...I'm quite sure it's on RCGroups somewhere. It is now a very ugly, beat up Jart (I built it by layering wide-weave FG over EPS, with a balsa sheated EPS wing), so I'll probably give it a complete makeover one of these days.

Journey to JARTdom - Part 2

2007-12-19T08:58:00.000+02:00

Making a plug

During one of the many mold making courses that I attended, I learnt that the first step towards JARTdom was to constructing a fuselage mold – a relatively easy, but somewhat painstaking task. I learnt that one approach was to use a medium grade wood for the plug (& I just happened to have some blocks of local Maranti handy - a medium hardness wood with a relatively close grain) from which a “female” plug is made. Later I decided that this wood grain was too course, & would rather recommend something with finer grain & somewhat softer density. After some research I found the correct version of the freeware Adobe Reader 6.x and printed the plans out using the Tiling feature (this feature is only available in the commercial version of later releases) onto A4 sheets & stuck these together. Soon this was transferred to the wood blocks that had been joined with a PVA wood glue (Lesson: this was a bad choice – as the water used during fine sanding wicks eats into this join & it creates a small mark along the plug – if you are thinking of doing this, use a waterproof glue).

I used a powered jigsaw and a plane to rough shape the blocks, after cutting templates from cardboard. The side profile looked awesome, but the plan view just did not “feel” right, so I modified it a little such that the nose was slightly narrower than the original 8020 shape. Then I applied lots, LOTS, actually HUGE AMOUNTS, of sandpaper until I had something that resembled a relatively smooth block of wood, which had even started to look like a JART fuselage amongst the copious quantities of wood shaving & dust. Did I mention that I used a small warehouse of sandpaper? I now understand why molded aircraft cost so much – it is all the sandpaper that is used.

First steps, the wood blocks are joined, rough shaped,…

... and liberal sanding is applied to create a smooth surface

Then came the interesting task of creating a smooth surface that would yield a polished “glass finish” type model – the stuff you see on all those fancy imported models. I started with common garden variety sanding sealer – boy this stuff smells just like the dope we used with tissue paper on those small free flight models we built as kids. It gives you the same headache too if you paint in a closed area.

After the first coat, the wood was all hairy again, and it was back to sanding until a silky “soft” finish is achieved (round about 400 grade paper). I then switched to water paper (600 grade) and had a “soapy” smooth finish after some effort. At this point I started to think that the building group would have to sponsor pay my medical bills for my tennis elbow! Around this time I also learnt the error of my ways when I elected to use a non-waterproof glue to join the smaller wood blocks, since the water used during sanding seeped into the join & created a small ridge, no matter what. Only dry sanding & later sealing eventually cured this.

After repeating the sealer & sanding most of it off again process for the third time, I sprayed (from a spray can) the first application grey primer paint & again removed 99% of this in the sanding process too. After I had used the entire can of primer (which equated to approximately 3 full coats sprayed on & subsequently sanded off). Just before the final sanding sealer coat & primer was painted, I “added” the 12mm thick balsa fin & had this smooth in no time at all. Unfortunately, I must have gained considerable upper body strength in the previous fuselage sanding process & proceeded to over sand the fin – which was now also a little sleeker than the original section, so I thought “why not?” and stuck it in place. I then applied a fillet of SikaDur epoxy between the fuselage & fin, and with a wet finger smoothed this until it also “looked right”. Sanding time….

I was struggling to remove the grain effect – the wood I chose was a little too course grained & water paper sanding down to the wood layer resulted in fine holes appearing. At the suggestion of an experienced friend, I mixed 10%-20% talcum powder into some sanding sealer & applied this as a surface sealer, before sanding it all smooth with 600 grade water paper. I also learnt the trick of adding a little dishwashing liquid to the water as this prevents instant clogging of the sandpaper. Finally I learnt that you have to wait until the sanding/sealer/talc combination is 100% dry – as tiny little bits are created otherwise which create long grooves in a nearly smooth surface. Oh well, nothing that more sealer & sanding could not cure.

My friend Evan (of F3B - Shongololo building group fame) advised me to use an automotive 2 part paint to create the best surface finish on the plug. So, Marcel, who had planted the orginal seedf, and who had sprayed 2K onto his aerobatic F3A models before, was lured over to the house with the promise of beer. He was soon set the task of spraying the plug (I looked after the beer part of the deal). The only mistake I made was to choose white paint only. If I ever do this again, I would spray layers with alternate colours (like white & black), as it really speed up identifying small holes/bumps during subsequent sanding processes. When it was my turn I learnt all about overspray, pinholes, orange peal & various other interesting “effects” that are achieved when spraying. Fortunately, and once again, it was nothing that a little sanding could not cure. In fact I have come to learn that sandpaper is your friend – my local sandpaper wholesaler provided me with a great wall calendar & even the recommended retail price list for 2008!

The 2 part automotive paint used to achieve the final surface finish

Around 3 days after spraying the frist coat of 2K, I started using 800 grade water paper, and admit that the water & dishwasher liquid approach resulted in a serious saving of the rain forest as I was now only using a few parts of sheet per layer (dunno what the carbon footprint of dishwashing liquid is, but being glider guider, I reckoned I already had to have some positive eco-points stored up already).

Post 800 grade waterpaper sanding – a smooth sheen is starting to emerge

After two more coats of the 2K paint I had almost eliminated all the grain marks & join lines completely. I finally switched to a 1000 grade water paper & managed to get a “buffed” surface finish – if you wipe a wet cloth over it, it shines. I thought that the time for polishing had arrived. Using a sponge polishing pad borrowed from Evan, and some G3 polishing compound, that matt surface was quickly changed into a shiny “new car” finish & at last I had a plug that I was proud of.

I took it along to the BERG club (current home of the F3B Shongololo building group) for a show & tell were we fooled around a little for the photo’s. The list of aspirant building group members has started to grow (note to self: I will have to create a formal list once the molds are ready).

Next stage: building the mold

Journey to JARTdom - Part 1

2007-12-19T08:38:00.000+02:00

Planting the seed

“Just look at that! It looks like its screaming fast & that’s when it is just standing still...”

It was another Monday morning way back in early 2006 after another awesome slope weekend at Volksrust. I was looking at the JART World website whilst talking to a good friend over the phone . The seed was planted, the decision made, & I ordered my set of personalized plans from Reed immediately. These arrived promptly the next day with wishes of good luck. Hmm. Little did I know how much those words would be prophetic, as a series of poorly chosen jobs at lousy companies, saw a number of years poured down the drain with no viable returns & completely unnecessary levels of stress. I trust that suppose the old saying; “that which does not kill you makes your stronger”, would hold true.

But that seed had been planted….

During this torrid period, I was also became aware of the “building group” approach to composite RC model construction. The ethos is simple: you build it all yourself, but the support system is awesome: guided by people that have done it all before, using all the proper equipment & techniques! During mid 2007 some of the local flyers started to get JART fever. Talk started emerging in hushed circles about a “new” pointy nose RC slope model that looked fast standing still. Vaguely remembering a plan that I had obtained many lifetimes ago, I wondered if this was the JART they were referring to,…, and sure enough it was. I decided that I had to do something about my building procrastination, even if it was only to prove to myself that I could also build it.

I approached a number of slope flyers & virtually all their comments were the same; “it looks awesome”, “I would love to try”, & “all this composites stuff is way too difficult”. How was I going to do this? Following another awesome slope weekend the concept of the JART & building group merged (probably fueled somewhat by the beers we drank at that late night BBQ). I emailed Reed to get permission for a JART building group, as I strongly believe in the DIY spirit he promotes through the JART. Essentially the “owner still need to obtain their personalized copies of the JART plan, they still build all the model themselves, but (the big BUT), they do so under the guidance of a building group. Using the building group’s fuselage mold, obtain onsite assistance in cutting the foam core wings & stabs, have access the composite materials depot (buy in bulk & save!), and also share the necessary facilities & tools for composite construction. Remember the process is as much about learning to build using composites, as it is about producing a great slope model.

I was immensely pleased when Reed gave the go-ahead for this as I already had a longish list of people who were very interested ion learnign to build with composites, but did not have the need for ther large F3B/J RC gliders typical of these groups. My challenge now lay in the tooling & skilling up for the building group.

I had attended most of the necessary composite workshops, where I had built or assisted building fuselages, bagged & hollow-moulded wings. I built a workshop with express purpose of kitting this for composites. The next step was to get my hands dirty!

Piet's Jart

2007-12-14T07:06:00.001+02:00

Piet's earlier posting on his Jart was on the BERG Blog. So I have moved it here so we can see his progress. I would hate to see any Jart builders in South Africa get left off this Blog.
As you can see he has already completed the fuselage. It is a lost foam one so no moulds. Nice and sleek> He bought it around to my place to show me and I took the photos, so luckily I was able to get them on this Blog.
We also cut a set of foam cores so he can bag his own wings.
We wait with anticipation for his postings on the progress of the wings?????

Fiberglassing the fuselage - Evan - Post #6

2007-12-13T12:31:00.000+02:00

After filling the defects with wood filler (the brown stuff) and sanding smooth, I have covered the fuselage with 2 layers of 163 gram cloth. On the sides of the fuselage the cloth overlaps so there are 3 layers there and a 4th patch for local reinforcing where the wing will go through the fuselage.
I have used LR20 Resin with SLC30 hardener. Between layers, any hollows were filled with microbaloons and resin mix and sanded flush.

After the 163 layers have cured. The lumps and bumps are water papered off and the whole lot smoothed off, then a final layer of 106 gram cloth is applied.

This final layer is then water papered as smooth as I can get it in preparation for spraying.

The map below shows the visitors to this blog on the 9th December 2007

2007-12-09T06:44:00.000+02:00

It clearly shows just how widespread the Jart revolution is throughout the world. Quite amazing!
Well done, Reed! You have certainly created a very unique, interesting and no doubt popular slope soarer.

Fuselage Shaping - Evan - Post # 5 -

2007-12-08T18:39:00.000+02:00

I have decide that I will probably only make one Jart so a "lost foam fuselage" will be fine for me. Besides being a lot of work making plugs and moulds and the fact that Jarts don't mind being a bit heavy I don't have to worry too much in that department. So a slightly heavy one of lost foam fuselage, painted afterwards it will be!

In stead of getting my plans printed full size I traced them in AutoCAD and printed them out full size on my A0 plotter. (BTW if anyone wants a printout you can come and get one from me. Just bring me your personalised Jart drawing that Reed has sent you and I'll print you a full size AutoCAD version. I'll cost you a "six pack" though)

Then I cut the paper profiles out and glued them to a block of blue foam.

I fixed my cutting bow to the side of my workbench and hot wire cut the fuselage shape.

I cut the side profile first and then taped the off-cuts back on and cut the top profile.

When all the cutting is done you have a lump of foam, that at a wild guess, could possibly resemble a Jart.

Lots of sanding and the fuselage is taking shape nicely. No fin yet!

Boy oh boy, did I have fun cutting the fin. That 4 to 1 taper over such a short span was a real problem and I screwed up three times before I finally got it done. Not absolutely perfect, but with a little filler it will be fine. (see the melted notch in the LE below)

I glued the fin to the fuselage with polyurethane glue. A bit more sanding and a fillet will have the fuselage shaping completed.

Now I too can strike the "To infinity and beyond" pose.

Next comes the sticky stuff!

Disaster Strikes - Evan - Post # 4

2007-12-08T16:49:00.000+02:00

But please read the "Wing Bagging" post below this first before reading this one!

Well things don't always go according to plan. -- Own up! -- Who wasn't holding thumbs?

Two hours after the wing went into the bag the power went off and I lost vacuum. Fortunately I had used LR20 with SLC30 Hardener so the resin was well into the green stage, so I just held thumbs that the skins would stick.
The next morning I opened the bag and removed the wing. It felt okay! Was I going to get lucky?

So I stripped off the kitchen towel and Peel ply from the LE. So far all looked normal.

But as soon as I started lifting the Mylar I realised there was a problem. The paint started flaking off.What had happened is that I had left the paint on the Mylars for too long before bagging. In fact I had painted the Mylars about a month before. It was also a power failure that had prevented me from bagging the wing that day and I had to leave them until I could get another gap.

So another lesson has been learned. I normally paint and bag on the same day and have never had this problem before. It is obvious, but do not allow the paint to dry for too long before bagging.

What can I say. This is Africa and power failures are a very common thing!

But all is not lost. At least the bottom skin is more or less okay, and I will just have to live with the few patches that pulled off.

The adhesion to the paint was so bad in places that big pieces pealed away like Solafilm, so it was easy to removed all the paint on the top surface, which I'll sand and re-spray later.

Next, the fuselage!

Wing Bagging - Evan - Post # 3

2007-12-07T16:35:00.001+02:00

It's been a few weeks, but I finally got some time to bag the wings.

The first thing to do is cut the skins. My lay-up will be 106 gram cloth under the paint backed by uni-directional carbon. The top has three layers of carbon(one full length, one 2/3rds and one 1 /3rd) and the bottom two (one full length and one 2/3rds).
I use the Mylars and cut the cloth at 45 degrees on newspaper, exactly the same size. The Carbon is cut without newspaper and obviously not at 45 degrees.

The skins are set aside. Now onto the sticky stuff.

The Mylar sheet is placed on some newspaper with the painted surface upwards and the 106 gram cloth transferred to it and the newspaper removed.

Then the resin is dribbled on and squeegeed into the cloth with an old credit card.
When that is done the uni-directional carbon is placed on top and wet out. Some effort is required to remove the nylon threads that hold the carbon strand in place. But with some patience and a little extra resin they come away. Then the extra resin is squeegeed off.

The wet out skins are then placed onto the foam cores and a strip of Peel ply is taped to the Leading edge of Mylar.
The whole lot is turned over into the outer cores. What is not shown is the reinforcing ply web that was inserted across the joint and the Carbon carbon cloth, cut in the shape of a diamond that went across the center on both the top and bottom. The 1/3 rd piece of UD carbon also spanned the center on the top surface. My original intention was to do a plug on wing, but after seeing Mikes Jart, I changed my mind and have decide to do a one piece wing fixed permanently to the fuselage.
Then the other skins are placed on top of that and the peel ply pulled around and taped dawn.
This sandwich is then placed on some paper kitchen towel. Another layer of kitchen towel placed on top of that.

Now the whole lot goes into the bag. Which is sealed and the air vacuumed out. The Bottom outer core is carefully positioned underneath the bag so that the wing can lay nice and flat with the proper dihedral set. This dihedral was cut into the foam cores.

24 hours later I will open the bag and hopefull get a nice wing. Hold thumbs.

More later.

The Wings by Trevor & co.

2007-11-25T22:28:00.001+02:00

In the Bag

Unfortunately we never took photos of the polystyrene cutouts so I will try and explain what we did, after cutting out the polystyrene and giving it a light sanding,we joined the wings together and filed a groove along the wing on the C.G. big enough to put a carbon tube about 8mm in diameter and a length of 20cm along each wing. We then put 3 60g carbon toes on top of the carbon tube and along the whole length of the wings. Once all had dried and before bagging we put microbaloons in to fill in all the holes.

We polished the thicker mylar and panted it in our colours using the Ford Focus Orange and a pearl purple for Trevor, two blues for Wes and a lemon yellow with purple for Kobus.

I was very apprehensive when I bagged the first wing but was pleasantly surprised when it came out the mylar, I think for my first time bagging they came out perfect.

Only the fuselages to complete and will keep you posted.

Chat again

Trevor, Kobus & Wes

The Fuzz by Trevor & co.

2007-11-25T21:51:00.000+02:00

Hi Jarters

We started by cutting out the outline of the fuzz from the plans glued two pieces of

polystyrene together and glued the outline onto the polystyrene and took a hacksaw blade and cut a rough outline of the fuzz. After a lot of sanding using 80 grid sandpaper we got agood looking fuzz.

From the picture you can see that we have put on (wing-things) because we are not making the Jart as one piece, the wings will attatch to the fuzz with a carbon wing joiner.

We covered the polystyrene with 180g cloth and put carbon toes down the fuzz for strength. Sanded some more and scimmed the entire fuzz with microballoons and epoxy to create a smooth finish. They will be primed and painted.

Thats it for Today we'll chat again.

Trevor, Kobus & Wes

The Stab by Trevor & co.

2007-11-25T21:04:00.000+02:00

Hi Jarters

This is all new to me and will be trying to keep you posted of how we are doing with our build.

We are currently building 3 Jarts and have already bagged our stabs but in a different way and opted to paint the stab after bagging. When we cut the polystyrene it never came out to smoothly so we covered the polystyrene with 0.8mm balsa hoping to create a smoother finish.When we bagged the stab I never had very thick mylar so never painted the mylar, we put a lot of microballons and epoxy on the leading edge and trailing edge. We sanded and made the profile correct afterwards, it has added a little weight but that's ok.

Will chat again

Trevor, Kobus & Wes

To Infinity and Beyond

2007-11-25T17:51:00.001+02:00

Lionel came around to the flying field on Sunday to show us his Jart plug he has made.

He has made it out of Meranti and after hours of shaping and sanding it was painted with 2K , sanded and polished and the result is an absolutely splendid paint job. It gleams in the sun and is a smooth as a baby's bottom. Not a wrinkle or orange peel anywhere. The shape is spot on and he has got that pear shaped front profile exactly right.

He will be starting on the moulds soon and has promised to keep us all up to date as he progresses.

He tells me he plans on starting a building group once he has all the bits and pieces ready, so people who would like to build a Jart, but don't have the equipment or skills can join and get help and advice and get hands on experience while building their very own Jarts. I for one will be joining, just so I can get one of those fuselages.

-----------------------------------------------------

Unfortunately we did not go to the slope this past weekend as planned so Mike's Jart never flew. But we are already planning a trip for next month. Lets just hope Murphy does not hear about it again and stuff up the weather.

All things Jarty in Cape Town

2007-11-19T11:00:00.000+02:00

Hey guys,

Good to hear I’ll soon have some company on the slopes. Was getting a bit bored whizzing past all the other planes.

So far I have pulled 4 fuses from my mold, the first was a test and largely a throw-away, 2 are flying and 1 is waiting to maiden.

These planes are amazing in terms of their momentum and speed and the biggest pain with them is slowing them down enough to land.

I largely fly in the Cape Town area, specifically the southern area where we have some great slopes for all wind directions. I have a bunch of other planes but recently have only been flying the jart as is so much fun.

I have been building mine solid and usually weigh in at about 1.3kg’s and on a strong days I have even considered putting in some ballast. I have also flown in light conditions where I’m not sure I would even be able to maintain a bee or zaggi but the jart once going flies superbly in the light air.

Best advice; throw it off the slope and don’t be scared to dive it a couple hundred meters before pulling it up, takes some nerve in light conditions but once its got some air over the wings it easily comes back up.

Reed calcs for the CG are spot on, if you trim the jart to the specs on the plans then it will fly, guaranteed. My first launch was done with all hands off the stick.
I have recently been busy with other projects and not had much time to build or fly but looking forward to getting some good air time this summer.

The J Fleet

How to land a jart :)

Jart finishing

2007-11-16T07:57:00.000+02:00

Well the Red Baron would approve of the colour scheme, I really needed to add the stripes so that it is easier to tell the top from the bottom and to find if it goes down in the rugged terrain of the slopes.

The yellow colour has proved easier to spot from a distance than the darker colours, I have helped find several gliders at Volksrust by looking back up the slope from the bottom with binoculars and orange/ yellow and to a lesser extent white stand out well.

The canopy is starting to fit ok but still needs some work I have added two ply-wood tongues,

and may now attach it with small cap screws, (dont want anything comming adrift as this beast comes screaming past)

The radio gear I am going to use is as follows.

elevator servo Hitech HS 125 flat wing metal gear (this fits nicely and screws down into ply- wood blocks from the top)

Wing servos HS 85 metal gear servos(HS125s would have worked, but I have 85s MG available. )

The receiver is a Futaba ppm 5 channel but on one of the less popular 53mhz band frequency which reduces the risk of a shoot down.

Battery is a 4cell 1000mah NIMH.

One of the last tips which I have noticed is often overlooked, is to label your plane with your name and telephone number, On Volksrust gliders often get lost and recoved later ...if your name is on it your chances of getting it back improve greatly.

Mike

Mylar prepertion - Evan - Post # 2

2007-11-15T17:15:00.000+02:00

I mentioned in my previous post that I wanted to experiment with a paint technique. The Mylar sheets were cut out so that they match the foam cores exactly on all but the TE, which is cut about 15mm oversize. Then the pattern is marked on the reverse side, then turned over and masked with newspaper and clear DC fix shelf paper before spraying with 2K paint.

I used a special water based release agent on the mylars before masking. The DC Fix sticks okay and releases easily. Time will tell if this is going to be successful.

I will be laying up with Uni-directional Carbon, so the areas I want black will not be painted. The pattern is white and black on one side and white and orange on the other. The masking is removed when the white paint has dried and the orange areas are then sprayed.

The painted mylar sheet are then put aside and left to dry.

The next job is to reinforce the LE of the wing before bagging. To do this I cut two strips of 106 gm glass cloth at 45 degree, laid this on the table and put 4 x 12K carbon tows over them and wet them out and squeegeed the resin through the carbon and into the cloth with an old credit card.
These strip are carefully laid onto the LE , wrapped around and brushed down with a little more resin. A little resin is brushed onto the foam before the strip is added to help hold them in place.

This is left to go to the green stage before bagging.

Next post will cover the bagging.

An Airfoil Plotter for AutoCAD

2007-11-15T14:27:00.001+02:00

In the February 2005 R/C Soaring Digest I discovered an airfoil plotting program written for AutoCAD users.
Above is a screen shot of my AutoCAD at work. The Airfoil selection dialog box is open and my Jart drawing is in the background.

It sounded very interesting and as I use AutoCAD I thought that I would give it a try. I am no computer boff but I managed to get it all working without any problems. I just followed the instructions and installed the program and am extremely happy with the results.

No more manually inputting coordinates. It is done automatically for me. Phew!
I even went so far as to create my own button for Airfoils, so I don't even have to type anything. It's just a click away.

Below is the article as it appeared in the R/C Soaring Digest, with links to where you can download the program. If you use AutoCAD and want to draw airfoils then this program is an absolute must for you.

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An Airfoil Plotter for AutoCAD
by Dennis Mead

R/C Soaring Digest - February 2005

I have an airfoil plotting program written for AutoCAD users who design their own planes using that program.
This is a routine written entirely in Autolisp, so it runs within AutoCAD without depending on any external resources. It can be installed or removed almost as easily as moving or deleting a folder. No fancy installation/removal steps are needed.
When designing a model plane in AutoCAD, the routine can call up and draw airfoils directly into the drawing without having to use any other programs or intermediate steps. After the program is loaded, just type the word “airfoil” any time you desire and the routine is running. An airfoil can be selected and drawn to any length of chord and thickness desired. All that is needed is the airfoils’ X & Y coordinate data. The data files may have any extension: .dat, .cor, .vec, and even .txt.Very fast, very simple.
For more info, see the “Airfoil.readme.txt” file. Airfoil.lsp is also a text file so it may be scrutinized easily if you wish.
The original program was downloaded from the web back in 1995 and was deficient in several ways. I re-wrote some of the code and added to it in order to make it work easily. The original author is noted at the beginning of the file, but so far all efforts to find him have been futile. I assume that since the original program has been in the public domain for quite some time, that the original author won't mind the improvements.
The “AIRFOILS.exe” file contains the program, the “readme” file, and also several folders of airfoil data. The airfoil data files were gleaned from a number of web-based resources.

Inconveniences: Some airfoil coordinate data is tab delimited. For some reason, Autolisp cannot recognize the “tab” character, so it is not possible for the routine to sort this out. Rather than having to manually edit out tabs in the data files, I have included a handy utility which can take a whole batch of files and convert all of the tab characters in all of the files into spaces and then place these converted files into a new folder. This utility was written by a friend of mine for one of his projects and he kindly modified it for our use here. This takes care of the only real quirk in using Airfoil.lsp.
Other data requirements are easy to check and correct. See the “Airfoil.readme.txt” file.
The “Tab_2_Space.exe” utility takes a whole batch (folder full of) of airfoil data which is tab delimited and replaces all of the tabs with spaces. This is needed sometimes because Autolisp does not have the ability to recognize the tab character in data files. Most all airfoil data is space delimited, so 99% of the time, the utility is not needed... but it's nice to have because it saves so much time and the possibility of making errors when editing data by hand.

For Macintosh OS, too:
The Autolisp routines and data files will work on a Macintosh if someone happens to be running AutoCAD Release12 (the last version for the Mac). The only thing that you Mac users may not be able to run is the “Tab_2_Space.exe” utility... unless you have one of the Mac programs that simulate a PC. An alternative to “Tab_2_Space.exe” is a small text processor, Tex-Edit Plus, which can rapidly exchange the “tab” character for a “space” character and quickly go
through a series of text files.

Final notes:
You will find all instructions/descriptions in the “readme” files as well as in the header of the Airfoil.lsp file. Some of the readme files may not exactly reflect Macintosh AutoCAD usage.

I hope RC Soaring Digest readers will find this program useful. Now off to design that next model! We have to keep proliferating graceful flying objects y'know.
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AIRFOILS.exe (PC) includes the routine, readme file, Tab_2_Space.exe utility, and folders of airfoil coordinates. http://www.b2streamlines.com/AIRFOILS.zip

AIRFOILS (Macintosh) includes the routine, readme file, and folders of airfoil coordinates. http://www.b2streamlines.com/AIRFOILS.sit

Tex-Edit Plus can be found at http://www.tex-edit.com/

Mike's Jart controls

2007-11-15T08:38:00.000+02:00

These photos show the silicon hindging of the ailerons and the elevator.

The control surfaces are carefully masked onto the plane and checked for the right amount of free movement, then with something hard (I used the back of the scissors) you get a good seal of the tape to the surface(you can see this in the photo.

Next you apply a bead of good quality silicone (I use the marine type clear)and you half close the control surface, now you make up a scraper from some balsa scrap with a concave shape,
as shown on the left and you smooth the silicon bead down across the hindge line.

The control surfaces are held in the central neutral position with some tape and allowed to cure.

The tape is removed and the silicon checked (add some if there are any flaws) this should give a free moving hindge which is durable but easy to repair if required.
The whole aircraft will now require final finishing , to do this I will waterpaper the exposed carbon on the leading edges , the sealed wing tips the gusset between the wing and the fuselage and the tailplane and fuselage. Then the whole thing will be carefully masked and touched up with red 2k and my airbrush. Thats better all red now, some polishing is next.

I have some vinyl and will add some stripes to the wings for visibility the plain red is a bit boring .

The radio gear goes in next .

Cheers for now

Dear Father Christmas

2007-11-14T13:39:00.000+02:00

Please, please, wont you send me the following on Christmas day,

A full house composite Jart like the one in the photo below.

I promise I'll be good and behave on the slope when other pilots are around.

Thanking you in anticipation.

Many thanks

Stevie

MIKE SMART JART

2007-11-13T15:58:00.000+02:00

I will put my complete JART build thread with all the never seen before photos on this build thread when time permits.
Here are a few photos in the mean time , in the build sequence.

Sorry not the plane but the tools I use to route out the foam on the control surfaces prior to a coating of resin and aerosil/cabosil

On one of the forums someone asked was it possible to build a jart in a day.

The total time on this project is about 17 hours at present , however that excludes epoxy curing

times and paint and glue curing times...so I guess it is possible to build a JART in one day

(24 hours) I would use fast setting everything but why bother ,current life has more than enough pressure.

Hope it flies as good as it looks watch this space the road ahead is clear of any obstacles.

regards

Mike

Where to start - Evan - Post # 1

2007-11-13T09:25:00.000+02:00

I wasn't going to start my Jart until next year, but seeing as how I need to practice a paint technique that I want to you use on another project I thought that I might as well kill two birds with one stone and use the Jart wing as my practice bed.

In this post I will also cover some of the basics things like making the templates and the feather cutter which helps with cutting the wings.

The idea of making templates seems to deter some people, but it's actually quite easy if you know how. So I'll start at the beginning and go through the whole process. I'll also show you how to cut the foam cores and prepare them for bagging. Later posting will deal with the actual bagging.

Making Templates
Start off by printing out the templates. They are provided on the Jart drawing. But if you want something else, there are several programs available for printing Templates. (See the links under "Useful Software" on the right) Cut them out and stick them to some Formica sheet with Prit glue stick. (You know, it's the "Glue without the Goo") Formica is the same stuff that kitchen counter tops are covered with and I get off-cuts form the local carpentry shop. There are two thicknesses and I try and get the thicker one (about 1,2mm thick). It is harder to cut, but makes a more durable template. There are many other materials that you can use, but choose something that can withstand a bit of heat form the cutting wire and remember that steel or aluminium will also draw heat from the wire, so make them thin if you choose to use those materials.

There are many ways of making templates and the method I prefer is to use the two template system. One for cutting the top surface and another for cutting the bottom. This system gives you a nice solid base to work on and very little room for error and is much easier to cut wings alone. You could use the single template method, but it does have its pitfalls. The worst is that the template moves and you end up with an untrue wing. Another is that you accidentally get the wire on top on one side and the bottom on the other side.(Especially if you are doing this alone) You can imagine the results. Still another is that the LE tends to get badly melted away as you start the cutting. But ultimately, it's your choice.

Cut the templates out and sand the edges smooth so the cutting wire can slide along the template without snagging. Cutting the templates requires patients and a steady hand. Cut them slightly oversize and sand them down to the line. I normally cut free hand with a stiff blade, but a Scroll saw with a sharp blade works just as well. A smooth surface for the wire to slid on is very important though, as any nicks will cause the wire to snag and make ripples on the wing surface.

In the photos above you will notice that the lead-ins are not straight, but curved. I do this to allows the wire to be heading in the right direction before it reaches the LE and not get stuck in a corner. See photo below. I also provide a lead out section of about 10mm, with a little notch filed about half way along, to catch the wire as it comes out of the foam.

Cutting Foam Blanks
The next step is to cut the foam blanks. I always cut the foam blanks about 5 to 10mm bigger at the LE. This allows the cutting wire to enter the foam and reach the correct temperature before it actually gets to the LE. (See photo above.)

The easiest way to cut the blanks is to mark out the foam and hang your cutting bow on the lines and let gravity do the work. But it is important that your cutting table is absolutely level for this, otherwise the edges won't be square. Remember to make a left and a right wing and mark on the foam where the LE is. Sounds silly, but it does help. Believe me!

Put two pegs into the side of your cutting table so they can catch the wire as it exits the foam.

In the photo above, are the two wing blanks after cutting and you can see the cutting bow hanging on the side of the table on the pegs.

Cutting Wing Cores
Next is the actual cutting of the wing cores. I use a home made feather cutter, so I can do this job alone. But the cores can be cut just as easily by hand. It requires two people, one either side pulling the wire through and calling the stations to each other as you go. You will need percentage marks on your templates or on the foam blanks before starting.

A feather cutter works with a swing arm and a series of pulleys around which the pull strings go. Once set up and the heat turned on, the pull strings pull the cutting wire through the foam and over the templates. In the photos below the cutting wire has just exited the foam block. The Swing arm can be seen in the second photo. The cutting bow is suspended above the foam blank which is weighted down so it can't move.

With the two template method, it is very important to cut the bottom first and then the top and always cut from the LE towards the TE. The reason for cutting the bottom first is that the foam will fall down into the void left by the melting of the foam. Then the templates are changed and the top is cut. Experiment with scrap foam until you get the temperature and technique right.

NOTE: When you are cutting the bottom, you must press the wire down so that it follows the couture of the template. The tendency is for the wire to go straight across because of the pull, so some downwards pressure forces the wire down against the template. Once it has traveled about a third of the way you can let go the downward pressure.

Similarly, a little upwards pressure to help the wire over the first part of the top cut helps prevent any sticking.

Also, don't put too much weight on the swing arm. It must be just enough to pull the wire through the foam without resistance.

The feather cuter is designed for cutting tapered wings. The major cord is attached at 1000mm from the pivot point and the minor cord is attached at the correct percentage. To make calculating the correct percentage easy, I use a very useful piece of software that is freely available on the web called Foam Calc. It can be downloaded from either of these sites. http://www.igull.co.uk/page1/page7/foamcutter.html or http://www.sungun.co.za/black_eagle/foamcalc.exe

This program lets you set the major and minor cords, the core span and the attach points and then calculates the correct percentage for you. All very simple.

Things like the feather cutter really helps and is a very useful tool to have in your workshop, especially if you intend making more foam core bagged wings.

It is important that the templates and foam are held firmly in place while cutting and once the bottom is cut the templates must be changed so the top can be cut. Use whatever method you prefer to make sure that everything aligns properly so that you get a true wing.

When you have finished you will have a set of foam cores with a razor sharp TE. (See s 2nd photo below) There will be some fine hairs left after the cutting and these need to be removed so that your skins stick to the foam properly. Use a cotton cloth to gently rub them off and then blow them clean. More on bagging in subsequent postings.

The LE will also have to be sanded a bit to get it nice and round. Once that is done, tape the bottom outers together and glue the wing roots together. That is if you want a one piece wing. Place the top outers on top and weigh everything down until the glue sets.

If you have any queries, please leave a comment below.