Substitution of wood materials
 

About to copy an older (semi-) 1/2 A size model once again.

The tail feathers are made up from hard 1/8" balsa. They essentially are two die cut slabs with rounded edges. Instructions say simply to round edges before installation.

I do not have any of such hard stock in place around here. I would have to order such from a vendor. Usually, what I receive is quite light and flexible.

Can I substitute 1/16" A/C plywood for such parts and get away with it? I have several sheets of this1/16" plywood, but should there be any fluttering expected? This is (or was) sort of a fast flyer too.


Wm.

RE: Substitution of wood materials
 

I'd think light 3/16 would be better. You can remove a little interior material if you're worried about weight. 1/16 ply would be too flexible. Actually, the light, flexible 1/8 would probably be fine after you get the 'kote on.

RE: Substitution of wood materials
 

A lot of old designs contain old thinking that needs to be rooted out. Heavy wood should only be used in doll houses. For a 1/2A plane, medium or even light 1/8" sheet is enough for any stabs up to 14 " in span. 3/16" that is airfoiled is a nice choice, too.

RE: Substitution of wood materials
 

If you glue together two sheets of 1/16 it will be stiffer than a similar weight 1/8. If you really want to get fancy, build up a 1/16 x 1/8 stick Warren truss framework and sheet both sides with 1/32 sheet. You will be surprised at how stiff it is.

RE: Substitution of wood materials
 

I've built this style in a number of different dimensions from 1/2A up to .40 sized. IMHO, this construction yields the lightest and most stable structure you can build.

RE: Substitution of wood materials
 

The overall parts in question are about 4" by 3" and I think some of the suggestions far exceed even the original construction.

Remember, this is 1/2A and not a biggie.


Wm.

RE: Substitution of wood materials
 

V-tail? If that's what we're talking about then just about any 1/8" should be fine. Without details you're going to get a wide range of suggestions. I didn't see any that were out of line for the range of possibilities.

RE: Substitution of wood materials
 

Whoa, stay away from the 1/16" ply sheet. Flexible, heavy, warp prone.

Thicker, lighter wood as others suggest and nicely sanded is a good way to go. Lighter then hard 1/8" should be absolutely fine, but ideally try to find some C-grain for the added torsional strength. No shame in using decently airfoiled light 3/16" either.

I think a lot of older 1/2A designs (perhaps some newer ones too) were on the porky side. I get a laugh out of reviews of 1/2A kits or construction articles that come out at 20-24 oz. My first scratch built 1/2A R/C aerobatic bird came out at about 11oz, with a flat 15% symettrical wing, I can fly it to my hand and catch it, and I've also thermalled it.

MJD