Progress - down the twisty road now!!

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

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!

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?

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!

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!

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

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.