Build Log Tabooish Build

[markStockton]

I'm in the process of building my 5th and 6th Tabooish DLG glider based on the information published by Phil Barnes here .

Hopefully this will stimulate discussion amongst home builders in order to refine the structures and techniques used.

Most of the structural development has revolved around the wing and fuse pod structures. Initially I used pods supplied by Atlanta Hobbies however I had some issues (that have been documented by other users else where on this forum). I have now made my own pod mold.

I've included a pic of #2 which I took over to Slovakia for the F3J WC. This model used the Atlanta Hobbies pod and boom with my own pink foam wing with 2mm pultruded carbon spar caps and skinned in 60gram kevlar / aramid. It weighed 300grams. #5 and #6 use 36gram aramid and 1.5mm spars. It look's like the weight saving in the wing will be at least 20 grams.

Till later.

[markStockton]

The story starts with routing the channels for the pultruded carbon fibre spar caps. I'm not going to go into detail on cutting and preparing the cores as there is more than enough information on the net about doing this.

I use 2mm diameter on the heavy duty wing and 1.5mm on the light. The caps are pushrods supplied by our local Graupner agent. A note here is that some kite shops sell black fibre glass rods as carbon. You pick this up when you sand of cut it and you end up with white dust.

To route the channels I use a Dremel with a suitable ball cutter bit in it and in the standard router attachment. I ruler is used as a guide and the first pass is done with the router running on top of the second ruler. This slightly raises the bit and creates a cleaner cut.

The caps are then tacked in place with a couple of drops of foam safe cyno.

BTW - The 1.5mm pushrods save 8 grams over the 2mm ones.

[jirvin_4505]

Mark
Just to let you know I am looking forward to your build and wing weights

cheers Jeff
Picked up a pile of 1.5 carbon here on the rcgroups recently - looking forward to a use for them.

[markStockton]

Originally Posted by jirvin_4505

Mark
Just to let you know I am looking forward to your build and wing weights

cheers Jeff
Picked up a pile of 1.5 carbon here on the rcgroups recently - looking forward to a use for them.

Hi Jeff

Here is a sneak preview:

Wing's joined with servo bays routed and flaperons cut-out etc. Still requiring reinforcing tape, servos wiring etc 124 & 120 grams

Fuse Pod made of 3 1/2 layers of 68 gram carbon (on bias) 15.5 grams

Tail (2mm balsa, bagged in 25gram glass (on bias) 10.3 grams.

BTW - Does someone out there know what a Taboo GT wing panel weighs?

Regards

Mark

[Mitch-air]

Originally Posted by markStockton

BTW - Does someone out there know what a Taboo GT wing panel weighs?

Best of luck with the build Mark, I'll follow with interest.

I have put several Taboo GT's together. The lightest panel I had was 56.4gram and the heaviest 58.7gram. These were supplied in two kits and there was at least 6 months time between each kit being supplied. There was no more than 1grm difference between the panels in all of the kits. I suppose you could look at an average per panel of 57gram as being normal.

Hope this helps.

Pete Mitchell

[Phil Barnes]

Pete's weights are still typical for current production TabooGT wing panels. More agressive mopping of epoxy could make them a bit lighter at the expense of a rougher surface texture and the hazard of delaminations. I consider 56 to 57 grams to be a target weight when I make them.

[markStockton]

Originally Posted by Phil Barnes

Pete's weights are still typical for current production TabooGT wing panels. More agressive mopping of epoxy could make them a bit lighter at the expense of a rougher surface texture and the hazard of delaminations. I consider 56 to 57 grams to be a target weight when I make them.

Thanks guy's thats really cool. The two wing's I just produced where 60 grams for the lightest and 64 for the heaviest. With the wing with the carbon reinforcing for the tip blade coming out 2 grams heavier than the other. On the heavier pair I ran out of kitchen towel so I couldn't be as aggressive with the mopping.

I'm happy to be within range of the Taboo GT as I consider that to be the benchmark to aim for.

BTW - Later today I'll post the wing lay-up process that I used.

[markStockton]

Anyone have any idea what a Taboo pod weigh's. My best two pods are as follow's:

3 1/2 layers of 68 gram carbon on bias + 1 layer 86 gram glass - 15 grams

4 laters (3 on canopy) of 71 gram carbon / kevlar hybrid - 14.1 grams

[Geode]

Just a reference point with slightly different layup ...

Taboo-like pod with 1.7 oz Kevlar + 5 oz carbon + 2 oz glass = 15 grams.

[markStockton]

As promised here is todays offering.

For me the wing prep starts with making wax paper templates of what the aramid skin should look like. The way I do this is I trace the mylars (which are 5mm wider at the trailing edge and do not meet at the leading edge when sucked down). Then I trim 10mm off the trailing edge and 5mm off the root of the wax paper templates. This makes sure that the aramid doesn't overlap the leading edge and tip. At this stage the wax side of the templates is dusted lightly with 3M77 and applied to the rolled out aramid. In this case 36gram, but I also use this technique with 60 gram aramid as well 68 gram carbon. Now one simply cuts around the edge with some kevlar sheers. (I really recommend you buy an electric pair, they make this task a pleasure.)

Once the skins are cut I turn my attention to the cores leading edge. I cut a 25mm wide strip of kevlar that is long enough to go right round the tip with some spare. A nice trick recently discovered is that you get nice straight strips if you clamp a straight edge down to the table and lay aramid over it and then run the cutter against the straight edge. Once the strips are cut I make little half width cuts every 10 to 15mm around the tip so that the aramid can be folded easily.

As you can see in the photos, I lay out the strips on some news paper, spray with 3M77 and then attach to the LE starting at the leading edge. I don't soak the strips in glue, but it isn't a light dusting either. Once the very front of the LE is attached all the way round I fold and smooth the aramid onto both the top and bottom surface working from the tip to the root.

After both wing's LE's are done I will go over them again with a Monokote iron on medium to high to really smooth out the strip.

At this stage I set the cores aside and prepare the mylar with a single layer of RAM wax (polished off after 30 minutes), prepare a bag and test the vacuum pump.

Cheers for now, I'm off to go do the stab mounts before dinner. I'll see if I have time to post the lay-up photos tonight.

[jirvin_4505]

Mark - nice idea of aligning the LE material whilst it is still on the bench.

I usually play around with a long strpl of sticky material - swinging in the air - sticking to my fingers- twisting on itself - AHHHGGGGG

Your technique looks much calmer.

thanks Jeff

[markStockton]

For the wings I lay out plenty news paper to work on as this gets pretty messy. I then lay out mylar on the news paper and set out all the materials nearby.

BTW - I forgot a step from the preperation above. Right at thhe end of the process after polishing the mylars I attach a 25mm wide strip of peel ply or tear tissue to the outside of the leading edge with double sided tape. I attach it so that only 10mm is attached to the mylar and the other 15mm overhang's the leading edge. This step is because the mylar doesn't join or touch at the leading edge and the peel ply keeps the breather materail away from the LE making every thing much easier to finish.

BBTW - Forgot another step with the mylar, I tape the trailing edge of the mylar together along the root panel with 3 pieces of masking tape. A small 2mm gap is left between the panels so that they can fold properly closed.

Back to the lay-up. I use a very thin resin system with a relatively long pot life (40 minutes). I mix a small batch of resin (28 grams) and pour about half onto the first surface I'm doing. I then spread it around using an old credit card (which is pretty useless after buying the carbon, aramid and hybrid materials anyway ). I then add a little 49 gram glass reinforcing around the root where the wing is handled as well as the top surface where the servo is going to sit.

Now I carefully position the aramid (still attached to the wax paper) as close to the root, and trail edge of the mylar as possible. I then flatten out the aramid as much as possible. If there are any obvious dry or resin rich spots I use the credit card to redistribute the resin. Once I'm happy with the resin distribution I take a hard rubber (printers roller) and roll the skins as hard as I can. This step seems to scrunch up the aramid and close out the holes in the weave. During this rolling the wax paper will attemp to lift. Keep it in place until you are happy that you have rolled the entire surface properly.

I've found the best way to remove the wax paper is to slide the credit card under the root edge to hold the aramid in place and then in one smooth movement pull of the wax paper towards the tip.

I now make sure that the entire wing is properly wet out, not worrying to much about weight.

I repeat the process detailed above until all the skins are layed up. Also don't forget to add some carbon reinforcing (I used 200 gram) to the area where the throwing blade goes. I also make sure that this carbon over laps the the spars.

Once all the panels are layed up, I cover them with a single layer of kitchen towel and roll them heavily again. This is to suck out all excess resin. I then leave the kitchen towel in place and tune my attention to the cores.

The leading edge is wet out with a brush. There after I attach a layer of 49 gram glass (20mm wide) over the aramid. This serves as a non fluffy material to sand back to when finishing the LE. You shouldn't need to add any resing while doing this. In fact it is more likely that you will need to dab away excess with toilet paper.

Once the leading edges are done I thicken the balance of the resin with cabosil until it is the consistency of vaseline. I then scrap this mixture over the spar caps making sure I wipe away all excess.

I now lift the kitchen towel if there are any shiny wet spots I roll the area agressively with fresh kitchen towel until I get a dry looking matt finish. Lastly I brush a little thickened resin along the trailing edge as well as the bottom surface along the flap hinge line.

Now I assemble the cores in the mylar and tape more to help stop it shifting. Carefully check that the peel ply is still at the outside along the leading edge and tip and cover both top and bottom surfaces in single layer of kitchen towel as a breather material. Then off to the bag.

Finally I weight the cores down on a flat surface until a decent vacuum has been pulled. Before I finish off for the night I carefully rub both the top and bottom surfaces to get rid of any air bubbles trapped between the skin and the cores.

Good night folks it is pretty late here in South Africa.

[markStockton]

Hi All

Here is a sneak preview of the two finished models. They came in at 262 and 258 grams respectively. However I know the problem with the weight is the in the tails which are too heavy. The second model, if it had balanced without nose weight would have been 240 grams.

Now for the question, I have many, many more photos detailing the construction process. Should I carry on posting them? The reason I ask is that I've had no feedback on the above, which makes me wonder if it was found to have any value or not.

Mark

[jirvin_4505]

Mark
I am feeding back

Love the photos and write ups.

I see this thread has had 756 hits - thats feedbck!

I am not sure waht you would like comment on?

Decribe your hevy tails and maybe we can build a lighter set.
>Tail (2mm balsa, bagged in 25gram glass (on bias) 10.3 grams.

10.3gm all up tailgroup seems light

Are you building your own booms?

cheers jeff

[Ninjak2k]

Yes, I'm very much enjoying the construction details. Just didn't have anything meaningful to add. Please do continue posting the pictures.

Cheers,
Dan