filtr-RCU

HI FOLKS

I WAS WONDERING IF ANY CAN HELP ME. I HAVE A SET OF MOLDS MADE FOR A PATTERN SHIP. I WAS WONDERING IF SOME ONE KNOW WHAT WEIGHT OF CLOTH THAT IS BEING USED AND AND WHAT WEIGHT OF BALSA PEOPLE ARE USING FOR A WING.

RON

Mluvara

My Feedback: (10)

I believe in general, 2.5oz on the outer layer and 1.5oz on the inner layer is pretty typical, with reinforcements where necessary.

combatpigg

My Feedback: (3)

I just built a plane with 1/2 oz cloth on the surface [first layer] , followed up with 2 oz cloth for the second layer. In some places you will want to use a third layer of 2 oz cloth. The balsa sheeted foam wing is typically done with either 1/16" or 3/32" thickness wood. I GORILLA GLUED a pair of aluminum engine mounts in.

Ed Smith

Assuming this is a fairly large pattern airplane with a big fuselage. The first layer in the fuselage mold should be 2 oz cloth. This will prevent SOME of the inevitable pinholes. Follow this with two layers of 6 oz cloth. An aditional partial layer of cloth or carbon cloth could be used ahead of the wing to stiffen up the engine end. If you have carbon tow then wind some into a string and mold in at strategic high stress points. This method adds enormous stiffness and strength for very little weight. See picture.

If the wing is ordinary white 1lb foam I would recommend 3/32 wing skins. If the wing is heavier foam and/or has a spar system then thinner skins may be OK.

Ed S

Mluvara

My Feedback: (10)

I think I misunderstood your first post and responded for building a hollow core wing. oops.

Ed's suggestions are good for a fuselage layup.

filtr-RCU

No it is a hollow core wing.

Ron

Mluvara

My Feedback: (10)

In that case, 1/16" balsa with the 2.5 oz outer and 1.5oz inner is appropriate. Some opt to do different things around the ailerons (if they are skin hinged). And appropriate reinforcement (carbon tow, glass tow, etc) around the spar is necessary.

There's a few threads around here in the composite forum regarding composite wing construction.

Michael

Deadstik

My Feedback: (8)

Ron,

Ed is right on the money as far as a fuse layup including the carbon fibre tow to increase strength with very little weight. His "formula" is the same as I use to layup my pattern ships.

Dan

Carolina Custom Aircraft

combatpigg

My Feedback: (3)

The reason behind leading off with a first layer of tight weave, .5 oz cloth is so you won't see the heavy weave[of 2 oz cloth] and need so much heavy filler to finish the surface with. This method saves weight and has some structural value vs relying on dead weight fillers.

filtr-RCU

I am planning painting in the molds. If you look at the fuse in info that fuse is painted in the mold. Just moving up to the wings.

Ron

SCALECRAFT

My Feedback: (13)

If this is what your trying to do.

This model, of a 65"span Typhoon is layed up with aprox 5.0 oz glass with composite reinforcements. It is a free atmosphere layup. No bagging. The entire airframe, hollow wing set up for retracts, comes it at 3.25lbs.

Hope this helps

Steve

daven

My Feedback: (1)

On my Q500 wings, I'm using 1.4 oz on the outer layer, a 2nd layer of 2 oz over the hinge and trailing edge, then the rohacell 2 mm, and then a layer of .7 on the inside. On the bottom I add a piece of light CF cloth about 8" at the TE and fanning out to about 14" at the LE.

I paint in the mold also, and 1.4 oz is plenty light to get a good finish.

esamart

Steve!

You have quite a lot of work on your Typhoon? Anyhow I do not see any wing spar in the center section. I am afraid it wont take many G's to fail. Before flying I suggest you to make simple stress-test usinh bags filled with sand.

That type of construction is also prone to engine vibration. It sounds like a drum so glue seams fail in time.

Sandwich construction with designed carbon fiber spar/shear web would be a way to go in future. I hope you can use your current molds.

Esa

SCALECRAFT

My Feedback: (13)

Esa

I see your point that it may be difficult to see the spar. So I'll make it a bit easier to see the concept we use. This is an 11 year old concept. It is fool proof and yet economical. In the 11 years we have been flying these hollow composite wings, we have yet to have an in flight failure. In fact, the corsair wing construction you see has been crashed 4 times with only retract damage and not the concept failing even on impact. I flew it yesterday.

Although not indestructable, they are very durable.

Vibration. Epoxy resin can resist vibration much better than polyester. We use only epoxy. Aramid is also used, it acts as a viration dampner(spelling?) on real airframes.

If I missed your point please post pics if your wings and fuses, I'm always willing to learn.


Any questions or comments please don't hesitate.

steve

HVACMAN

My Feedback: (127)

Steve, keep in mind the pics that you have of the typhoon do not show rear balsa spar/hing mounts. I will install them and take new pics, should I show how my L.E. is seamed? No BUTT joints here.

Mike James

Show EVERYTHING!

Regardless of how we all do things, it's always good to see how others do it, and what their results are. I want to see everything that everybody does. We all learn something.

esamart

Steve!

I am ashamed I assumed there was no spar in the wing but the photo really fooled me. When you posted those other pictures I remember examining them elsewhere with great interest but did not remember.

Years ago when I wisited model airshow in Britain I saw larger WWII fighter perhaps P-51 which had similar construction. Builder told that inside the skin there was foam which was half circle shape and finger thick. Sort of skeleton glued and fiberglassed over to make skins stiffer and to reduce engine induced vibration. Anyhow it sounded different. I have read that sometimes engine vibration and finally G-force has destroyed epoxy/microballoon seams between spars and skins.

When I first saw and heard F3A models with sandwich wings they sounded more than balsa skinned styrofoam wings despite soft mounts. Anyhow I still believe that sandwich construction has advantage if sound level of the model and stiffness is compared with construction you use if they weight the same.

I understand sandwich construction started to spread among AC builders when Germans mass produced full size gliders decades ago. Then it surprisingly slowly spread to model business. Maybe it is overkill and wasted time and money to use it if just plain skins work fine.

I have Pierre Clostermans "Le Grande Cirque" in my bookshelf. I get bad feelings if I think that time but I admire those airplanes.

Thank you for sharing your success Steve!

Regards, Esa

SCALECRAFT

My Feedback: (13)

Esa

No big deal.

Enjoy.

Steve

ptxman

My Feedback: (2)

Hi Ron, hows life in 'the Jaw'? Patern wing molds,eh? Must be getting serious now! You should try & swab info off guys who have had the Angels Shadow. Im out of the F3A loop but there used to be some pictures posted of the wing layup procedure & that is probably the closest construction analogy I can think of to your application. From what I reacall (rusty memory) he used 2mm balsa which would = .078", somewhere between our 1/16" & 3/32" thickness (vac bagged). Dont know about density but thats kind of a double edged sword. Lower density like 6 pcf = lower core weight but also lower strength & more resin absorption. You will likely have to do some surface treatment like laquer or dope or something to prevent resin absorption into the core. Higher density like 8 pcf & the wing start getting heavy for F3A. These issues & the biggish surfaces is where rohacell & similar starts to look appealling but its not really necessary.

Onto your original question, my guess is something like 1.4 oz outer & 1.0 inner +/- 0.5 oz. Would probably benefit a lot from bias weave layup. The sandwich recipie will depend on a lot on other variables you will have to investigate & simply try, the biggest of which involves what sort of spar & internal supporting structure you will be integrating. The Russian Shadow pictures (I think) had the spar socket supported in some riblets but I cant recall what was there for a spar web or CF caps. The wing also had some outboard riblets & of course the aileron hingeline closeouts, control hardpoints etc. I remember the first AS's Ivan flew he had issues with the structure humming on the 4-bangers. It could be the riblets & more internal structure came in response to that. When I saw more of them at the CNats in Vancouver (yr 2000?) they seemed fine in that regard, but none of them struck me as particularly light compared to conventional foamy construction. You will have to watch your paint & laminating epoxy use & use peel ply on the bagging operation. If you are considering electric, it might be lightened up some more due to less vibration, but not by much I suspect.

Good luck, show us some pics of the result. How were the molds made BTW?

filtr-RCU

Hi PTXMAN

I have the moulds CNC. They look great.

I have been busy with work just getting back at it.

I hear your into plyon racing that is great.

Ron

Mike James

Peter is right.

I'm a big fan of the Angel's Shadow, and have followed it's development for a few years. Here are a couple of photos from the site at http://indigo.ie/~nbarrett/NoelPr.htm showing a minimum internal structure. The internal spars are blue styrofoam.

Great work.

The last photo is the interior of a friend of mine's Angel's shadow, here in Alaska. Note the interior "bracing" is a piece of white styrofoam.

Very light, but overall, a structure that's strong enough for F3A loads.

ptxman

My Feedback: (2)

Good score Mike, those are the pics I was referring to. I have a great memory, its just very short! Im not real keen on the single rib ttransferring the spar/socket load to teh skin. I would prefer integration into one of the spars, but whatever... it seems to work.

Regarding core materials, there is another (euro) material being discussed quite a bit lately called Herex, lower cost than rohacell. Havent used it mysef but the properties look interesting. Mentioned lately in a good composite F5D build thread here:

http://www.rcgroups.com/forums/showt...&page=24&pp=15

original thread starts here
http://www.rcgroups.com/forums/showthread.php?t=270446

herex dealer direct
http://www.gaugler-lutz.de/

also available from R&G (great composites link)
http://www.r-g.de/


And just to give you something to aspire to when it comes to molding high performance wings, or as David Fee says, "the mother of all molding threads"
http://www.rcgroups.com/forums/showthread.php?t=141255

and another one here:
http://www.rcgroups.com/forums/showthread.php?t=186917

can773

My Feedback: (1)

Hi Ron

There are a bunch of pictures here of PL doing their new design plane with all composite wings.

http://www.plprod.com/prov/fr/concep...onyx/onyx.html