1/8" Thick Trailing Edge on Swept Wing Foamy

[Armchair Bronco]

I'm currently building an ACT Me-163 S400 foamy.

The 28" swept wings consist of a single piece of styrofoam from which I need to cut out the 3/4-length elevons.

The trailing edge of the foam is slightly more than 1/8" wide, which strikes me as way too thick. I'm assuming that such a thick TE will negatively affect aerodynamics & flight performance.

The problem is that it is very difficult to uniformly sand styrofoam without chunking or breaking it, so my only real alternative is to replace the styrofoam cut-outs with balsa elevons. This, in turn, will add weight to a plane that I'm trying to keep as light as possible (< 14.5 oz).

So: what are the effects of a thick vs. a thin TE on a high-performance, swept wing craft (this model is capable of speeds in excess of 80 MPH)? And do the benefits of switching to balsa for a thin TE outweigh (pun intended) the weight gain?

[Sparky Paul]

Balsa will be stiffer than foam.
The control horns are better secured to balsa.
Add a balsa trailing edge for the hinges to go into, and tapered balsa elevons.

[Armchair Bronco]

Just curious about performance, though.

If I were to build two identical planes, except that one had a thinly tapered TE and the other had the stock 1/8" TE, how would the 2 planes stack up against each other? (We'll assume the same 14.5 oz weight for each.)

[raptor22]

How aerodynamic is the original plane? i doubt it would make much difference if you have a taped wrikled mess like alot of foamys. However, if it is reasonable aerodynamic then I think you would see a marginal performance increase.

--Alex

[Quacker]

Funny, I had nearly the same question about my FFF Staggerwing. The leading edges were just square. I decided to sand the L.E. on the wings on only the left side. I was looking for changes in stall speed, tip stall, natural tendency to bank, etc. Nothing, nada, epis, zupa, amazing.

Q

[Armchair Bronco]

How aerodynamic is the original plane? i doubt it would make much difference if you have a taped wrikled mess like alot of foamys. However, if it is reasonable aerodynamic then I think you would see a marginal performance increase.

Both the original (full scale) plane and the version I'm building are very aerodynamic (see the red Me-163 avatar/icon to the left). This EPS kit is small (only 28" wingspan) but the manufacturing quality of the fuselage halves and the single, swept wing is superior.

I may end up taping this plane and covering it with Ultracote, but even if I just sand and smooth the airfoil with lightweight spackle, I'm planning to keep the entire plane as slippery as possible. The finish won't be smooth as glass, but it'll be as close to glass as I can get styrofoam + clear packing tape + spray paint.