SA Jarts

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

JARTY Questions

2009-11-02T12:14:00.004+02:00

Having built and flown my 1st composite JART, not only does it generates a big smile on a face, it looks like it is flying significantly faster than I thought it would.

I'm busy with JART #2, but was wondering what speeds they are capable of?
Has anybody measured their speed, and at what wind speed?
This time I'm looking at split wings and the re-inforcement to cope with the stresses on them.

Also, do you use 4.8V or 6V packs?

Cheers

Johann

Agulhas Jart Flying

2009-11-01T07:08:00.009+02:00

Here's some flying video clips of my first JART attempt. (51 oz AUW).

I'm flying in a loose circle with a diameter of +/- 700m. The flybable slope in a South Wester is around 2000m. The video clip is not representing the actual speed, as at times, the JART just outran the camera.

JART Launch: On launch it shot up to a dizzy height while gaining forward speed.

JART in flight: Some seagulls gave chase, but it outran them. Once it gained speed, it is greased lightning.

"Take us to your leader, we want to build JARTS on Mars too ...."

I'm now building JART #2 - it will have some minor tweaking, based on experience gained with the first one. All in all a very nice plane to build and fly.

Maitlands

2009-10-26T12:09:00.002+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

2009-10-19T12:13:00.004+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

2009-10-16T08:34:00.004+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.

Agulhas JART build / Slope Soar Catch Net Update

2009-08-28T20:26:00.024+02:00

Finally my JART was ready to fly - with 51 oz all up weight – this puts it in the lighter side of the 40 – 90 oz range.
After trying a red and white colour scheme that did'nt work, I sanded it off and tried the white/blue contrast colour scheme – more visible in the air, and yes, it attracts seagulls… by the dozens…

I maidened it on 24 Aug 09 in a fair wind. It wiggled a bit after launch, got speed and flew straight and steady, only a little down trim required. It is fast, does loops and rolls nicely. It is fast but I'm sure it can be tweaked in to go even faster - any advice will be welcomed here. (more weight?)
The 1st landing was short of the catch net – came in too slow and the attraction of the protea bushes just got too much…..luckily no damage.

The next landing was faster, flying it straight into the net. I promised earlier to show the catch net, see attached pic and video clip. The net is 3m high and 4 m wide, the holes are 35mm x 35 mm. It is mounted between 2 upright telescopic tubes (aka paint roller twist & grip extention handles). The poles are anchored by 2 ropes a side with metal tent anchoring hooks. The net has a lot of “give” – slow stretch, thus you can fly into it at speed and it slows the plane gently down. The net is put up so that the plane flies into the wind into the net. It can also be put up sideways so the plane can drift into it with a cross wind. As the net is angled (lower side facing the plane), the plane stays in the net - almost like a pouch. When not in use, the net can collapse diagonally into a "net rope" that can be rolled up in a small bundle and lives in an old laptop bag.

(Click on pic's to enlarge it a bit)

Catch net rolled up

Next up is towing the JART with a tug plane – for those days when the wind is just contineously wrong for the slope.
I’ve installed a tow rope release mechanism in the nose of the JART. We will try this out around last week in Sept when I’m back.

Tow release servo installed

Tow rope hooked in.

All in all, a very nice plane and a lot of fun - and I enjoyed the build.

Next will be towing it with a tug plane, will keep you posted.

Cheers

Johann

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

JART build/Foam cutter update

2009-07-04T21:17:00.030+02:00

My first JART fuse attempt came out too tail heavy and I trashed it. After attending Evan's very interesting wing bagging course in Cape Town recently, I got going and re-worked my JART mould and built a JART to the point of installing the radio gear. This 2nd fuse came out much better and much lighter - very light but still strong - was not trying to "Protea bush proof" it with resin this time round (thanks for that tip Evan)..... Because of the dense bush and scattered limestone rocks, I'm now using a 4m x 3m soft, stretchy nylon catch net at the slope, so don't need it super strong anyway.

As this build is a learning curve for me, I'm building it light. I'm fitting a moulded polycarbonate canopy with a "glass" frame to save weight and for better access - the re-inforcement around the rim of the canopy area is still lighter than the original cut away "glass colth canopy". I'm also fitting a tow hook receptible thingy so we can tug tow it at the Bredasdorp Model Areo Club if the wind is wrong for sloping. The JART design sure has some sleek, graceful lines....looks like it's doing 100 mph standing still....

In between working on the JART mould and laying down a fuse, I started building a feather cutter. It is amazing how easy this "one man" thing design works - no more scratching heads cutting wings with templates and pins that keeps getting into the cutting wire.

I'm fitting Hitech 125 MG slim wing servos. With all this done, I will hit the Agulhas slope within the next couple of weeks. Curious to see this plane fly - from videos I've seen, it looks like it can outrun a bat escaping from hell.... the unknown factor will be at what speed JART will meet NET....maybe end up with a frayed smouldering hole in the net...will post the pics in due time....

I came accross the photo above - looks like the JART's dad was a jet fighter - some pedigree!

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.