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Sep 22, 2013, 01:33 PM
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Quote:
Originally Posted by OozyToast
Attachment 6121872

Poly on the tail set
It wasn't clear whether you were using glass with the poly. Poly alone won't stiffen things up much, but if you put a layer of .75 oz glass with it you get a very stiff wing.

All the stiffness comes from the glass and the poly just holds it in place.

The DL 50 uses this technique and flies quite well. You can get a manual at
http://www.mountainmodels.com/produc...roducts_id=212
to see how they do it.

The poly is much nicer to work with than epoxy. It's water clean up and quite light.

Gord_W
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Sep 22, 2013, 02:45 PM
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dion9146's Avatar
Be careful with water based ploy however. If you put it in sheet balsa, you have to coat both sides or it will warp. I know, we are talking about foam. The only thing it adds to foam without fiberglass is unneeded weight as Gord points out.
Sep 22, 2013, 07:00 PM
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V2 finished


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Sep 22, 2013, 07:14 PM
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Maiden


DlgV2 half strength test (0 min 20 sec)


Dollar foam dlgV2 test (0 min 14 sec)






Didn't get a full strength throw in before I needed to reinforce the nose

Thanks for the info about glass and those tail feathers. Both those tips will go into v3

As it is it weighs 256 grams and floats like crazy but it was too windy to really see what it can do. I will update when the weather is better.
Last edited by OozyToast; Sep 22, 2013 at 07:30 PM.
Sep 22, 2013, 07:58 PM
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what is the wing span of V2 ? it looked good in the videos...its been windy here as well as tends to be in fall lol and fall is my favorite building season for models. also what size spars did you use in the wing ? great job and effort
Sep 22, 2013, 08:15 PM
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Thread OP
The wing span is about 56 inches and I ended up using the arrow shaft for the boom. For the wings I used a flat carbon spar inlayed vertically in the top and some carbon tape on the bottom stuck on with epoxy. The wings are still not as rigid as I would like without cloth.

I should be able to get twice the launch height I did in the video I hope
Last edited by OozyToast; Sep 22, 2013 at 09:00 PM.
Sep 22, 2013, 09:39 PM
It's time for me to fly
JimZinVT's Avatar
You're right in the same weight range as some of the best DLGs in the world

Looks like she needs a little tweaking of the elevator trim &/or CG....she's flying right on the edge of a stall. But she's going to fly well.

Do you know about Curtis Suter's "Sailplane Calc" spreadsheet? Very easy to use: you just plug in your plane's dimensions and it calculates the CG location and whether you've sized your tails properly. I've used it to design a couple foam & laminating film DLGs that fly beautifully. And he generously offers this program to us free.....thanks Curtis!

On the laminating film: it is a fairly lightweight way to give your wing more stiffness....it just irons on. Although light glass and PU I think will give you a stiffer wing.
Sep 23, 2013, 06:04 AM
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Thread OP
Thanks for the tips Jim I will get the calculator for sure

Can you tell me more about the type of film you are using ?

Is it just monokote ?
Sep 23, 2013, 10:45 AM
Will fly for food
davidjensen's Avatar
The videos looked like the CG was to far aft.
Sep 23, 2013, 05:10 PM
It's time for me to fly
JimZinVT's Avatar
Quote:
Originally Posted by OozyToast

Can you tell me more about the type of film you are using ?

Is it just monokote ?
Not monokote....it's the laminating film used to seal photos, certificates, cards, etc. between layers of plastic. It's sold by the foot by Aloft Hobbies and Canuck Engineering, or in bulk rolls by Laminators Warehouse. It's been popular for years with the slope combat wing crowd, going by the name "New Stuff". It's become popular for covering the ultralight slope aerobatic planes like Le Fish, Flow, Buzz, etc. using the thinner gauge films....1.7 and 3 mil mostly. It adds a lot of stiffness to foam without adding much weight.

I use the 3 mil to cover the hotwire-cut foam wings on my 40" home brewed DLGs and also to add stiffness to the 1/16" balsa tails. Not as stiff as "proper" glass and epoxy wings, but stiff enough to launch and fly nicely, and reasonably durable. I haven't tried the 5 mil, but I think it would make a pretty stiff wing if it will conform to the leading edge well.

For techniques you can search the slope forum for "laminating film" or "new stuff", and in the "Swiss Fish" thread, or look at my "SAL-40" thread in this forum. It's pretty easy to use. It doesn't really shrink when ironed, so compound curves like wingtips are dealt with by slicing and overlapping the film.
Sep 23, 2013, 05:42 PM
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Jim Zin ill have to give that new stuff a try. i have just used clear packing tape on my hot wired wings but bet the Stuff is much better. ill get some asap
Sep 23, 2013, 06:53 PM
It's time for me to fly
JimZinVT's Avatar
Well I haven't tried the packing tape, but from everything I've read, it's lighter, and stiffer (because it does not stretch). The added expense is the only drawback.
Sep 23, 2013, 08:25 PM
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Well something failed on launch, not sure if it was the wing or the pod/fuse

I'm glade I didn't use that nice carbon pod from Pat

I had a lack of reinforcement where the wings join, time for hot glue and packing tape.

But this build might not be one to copy
Sep 23, 2013, 08:53 PM
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i would just go with a balsa pod, the wings being dollar foam board was a challenge you me and prevailed
Sep 23, 2013, 09:07 PM
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Thread OP
I think your right, I will use balsa or i thought some type of plastic bottle might be even stronger.

the wing is repaired and now reinforced with packing tape should be back in the air soon.

Are you building one Larry?


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