News From Reed at Jart World

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

After attending Evan's very interesting wing bagging course in Cape Town recently, I got going and finished off my JART mould and built a JART to the point of installing the radio gear.

The 1st JART fuse came out too tail heavy and having done Evan's course, the 2nd one came out much better and much lighter - was not trying to bullet proof it with resin this time.....

Inbetween working on the JART mould and laying down a fuse, I started building a feather cutter based on Evan's. It is not completed yet - the main cutter is done but the larger bow made from a broomstick and piano wire started bending the broomstick - need to get a sturdy oak plank or something and 2 sturdy metal rods. The smaller bow don't have the same problem.

With all this done, I will maiden the JART within the next couple of weeks and work on improving my building skills - looking forward to that.

New kid on the slope

Hi everyone, I came accross this very interesting site and could not resist joining up to learn more about all the materials and techniques being used. I've been tinkering in my own way with glassfibre but the professionalism of work on this site just told me to get involved, learn more and try to achieve that same level. It so happens that I'm busy making a mould - but approached it differently.

I've cut out 2 of 3 mm coated ply side silhouettes, place a 2mm sheet of clear acetate between them, joined them with locating dowels down the middle, then cut out a separate a plan profile using 3 mm ply, split it lengthwise and glued it onto each outside of the "silhouttes", thus forming the backbone which can be splitted down the middle. Then filled the sides in with dense polystyrene thermal insulating foam (ceilings) and shaped it, PVA and layer it with glass cloth, building layers and sanding it down to a smooth finish (the acetate sands slower than the wood/glass, thus make a neat joint), followed by a couple of coats of K2 paint and 400 grit sand paper. Then split it down the middle and glue it with PVA filler glue to white chipboard. I then sprayed waterbase mould release liquid on the mould, followed by gelcoat, resin and cloth. Then building up layers with glasscloth for support, ending with heavy duty "glassfibre mesh". Albeit very "Heath Robinson", I actually found it easy to make this primitive mould. Pre-drilled holes for bolts in the chipboard lines up the two halves.

The 1st fuselage came out without too much trouble but was too tail heavy. I'm re-working the mould through lessons learned and hopefully fuse #2 will be better.... but then I discovered this site - oh boy...

I've made the wing and tail from white foam and covered it with balsa.

The main slope at Agulhas where I fly will be ideally suited for this type of glider, but the vegetation tends to destroy anything except mugi's on landing. To overcome this I've had a 4m x 3 m net made - to fly/stall the planes in. The net is very soft/elastic.

But I think glass/carbon fibre enforced wings/leading/trailing edges/fuses will further reduce damage - and this is where this very interesting site will come in handy - trying out various high tech construction materials/techniques - man, I feel so "last century" with my normal fibreglass mould and balsa covered foam wings...... but not for long...

Johann & Daron

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!

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

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

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.