Pros & Cons-Composite frame vs. wood airframe

[prizzy]

I have 5 flights on my new wood plane. I am still not sold that the benefits of a wood plane are more than a comp. I DONT like the maintenance of the wood plane.

[alec taylor]

all my planes are built up. there is no maintance problems if built right. but i do not cover with plastic film. alex

[leeMcCrory]

I was flying at Weston park show last weekend were i got talking to one of our best British Pilots Nathan Farelll Jones who was flying a 39% Krill katana and a Comp arf 40% Giles. It seems the krill was much thicker in construction so flys a bit heavier than the Giles. Nath told me After getting home he shines a torch inside each of the fuses to look for stress cracks. The Katana always shows up quite a bit of stress by the undercarrage after every outing. Even with Soft landings its inevitable that extra glass will be added for strength at some point, So are these compys just boat-anchors in the making? Im happy with my Ef 110" Yak. Wood Is Good eh.

[jaguar bone]

Well, I'm still hording my pile of cash.

[smokin]

as i said before, i have a comp arf yak and a comp arf superxtra... i absolutely love the durability and lack of hanger rash! now i have wood planes as well and i enjoy them but the maintenance is higher. ironing, ironing, ironing. and i'll admit... i really like the comp-arf squeal!!!!!!

[why_fly_high]

	Quote: Originally Posted by sensei
	I have made my living manufacturing composite products for the aerospace industry for nearly 30 years now, and I have also owned several C/A 3.3 Yaks, all sweet aircrafts and I enjoyed them allot, but the truth is; it is less expensive and more acheivable to build a balsa airframe lighter than an all composite airframe I have some ideas that I will try soon on a molded balsa/composite hybrid airframe that would still be open bayed and covered with Monokote. I believe this would be the lightest structure of all and possess great structural qualities. Bob

Bob,

Molded balsa composites? Take a look at these from OSU. The bipe has a 6 foot wing span and has a ready to fly weight of 4 pounds. The monoplane weighed 3 pounds but was a little smaller.
http://good-times.webshots.com/photo...54282401GPybhu
http://good-times.webshots.com/photo...54282401hakESV

Dan

[Mithrandir]

There is a point at which a truly optimized Composite plane.. (Meaning; consisting of Fiberglass/carbon fiber/epoxy resin/ core.. honeycomb, foam or even BALSA core) clearly exceeds the "Peformance" of a "wood only" plane.
In my Professional opinion, a 30% model is best achieved with a primarilly wood structure... perhaps carbon uni spar caps and S-Glass or bid carbon shear webs.. local composite reinforcement inside the fuse.. like around the LG plate and Firewall/Engine box.. etc.

A 100 cc plane is more nebulous as to wood or composite being better...

A 3 meter plane can definitely be lighter (At the same strength!) then a wood plane. With proper techniques... the airframe will not "Oil-soak and fatigue" like a wooden plane as well.

By "Better" I mean same strength/stiffness, less weight and less routine maintanance.

Wood lends itself to easier fabrication for one or two models... but if you are gonna make multiples... composite molding will result in more uniformity from plane to plane with proper tooling....

Composite fabrication is NOT hard.. it is just Different.

[jaguar bone]

	Quote: Originally Posted by why_fly_high
	Bob, Molded balsa composites? Take a look at these from OSU. The bipe has a 6 foot wing span and has a ready to fly weight of 4 pounds. The monoplane weighed 3 pounds but was a little smaller. Dan

Man but that is a TON of UGLY tho!!

[why_fly_high]

	Quote: Originally Posted by jaguar bone
	Man but that is a TON of UGLY tho!!

That was the MIT foamy plane. The contest was to carry about 8 pounds of payload with the lightest plane. it wasn't a beauty contest.

Dan

[BoneDoc]

Mit,

If you've seen the "Carden 260 on a Diet" you'll see that a properly fabricated wood plane is still lighter than a composite plane . I've gotten my Dalton 35% 260 to 19.5 lbs electric. Can a 35% composite achive or go below 20 lbs?

[Mithrandir]

	Quote: Originally Posted by BoneDoc
	Mit, If you've seen the "Carden 260 on a Diet" you'll see that a properly fabricated wood plane is still lighter than a composite plane . I've gotten my Dalton 35% 260 to 19.5 lbs electric. Can a 35% composite achive or go below 20 lbs?

It can be made lighter from composites... but there is a point of just being unrealistic...

example... Carbon cloth at a 6 oz/yd costs $40.00/yd. Carbon cloth at 11 oz/yd costs $65/yd... both are really too heavy to be practical for models.. 3.7 oz/yd Carbon cloth (1K( costs $70.00 per yard...

With RC planes, the amount of composite required to take airloads sometimes results in skins that are very thin and fragile, vulnerable to handling....

IMHO, 35% is about the size where practically, composites can exceed wood.

[why_fly_high]

	Quote: Originally Posted by Mithrandir
	It can be made lighter from composites... but there is a point of just being unrealistic... example... Carbon cloth at a 6 oz/yd costs $40.00/yd. Carbon cloth at 11 oz/yd costs $65/yd... both are really too heavy to be practical for models.. 3.7 oz/yd Carbon cloth (1K( costs $70.00 per yard... With RC planes, the amount of composite required to take airloads sometimes results in skins that are very thin and fragile, vulnerable to handling.... IMHO, 35% is about the size where practically, composites can exceed wood.

Very true Mike. Lightening wood airplanes usually lowers the cost as you use less wood through better engineering. Lightening composite airframes tend to make things more expensive.

Dan