ORIGINAL: sensei
ORIGINAL: Campgems
ORIGINAL: Alex7403
I wouldn't do this.
plywood stands better through stress than balsa.
stress = force / area
means you need much more balsa to stand the same amount of stress as plywood.
who ever designed this airplane didnt choose balsa for a reason.
how many ounces do you think you are gonna win?
while you are risking the whole airplane.
cant you just put a bigger motor?
I dont know the global raven 60
Sound advise. If the sides are warped, build the fuse with the warps fighting each other. It is almost impossible to get absolutely straight wood, be it sticks and sheets or ply. Build so the warps are in oposition to each other to equal a straight build.
I'm working on an older scratch/plans built pattern plane. It has the old school balsa sides, and it weighs a ton, 13 lb actually, I bought it third hand from an ex club member. I could probably cut the weight down to around 8 or 9 lbs using a lite ply construction vs the balsa sides and bottom.
When you have to cut a window in the side and put a frame to screw a lit ply sheet to to mount your switch to because the balsa sides are to thick for the screws, lite ply construction sounds better and bettter all the time. I'm talking about a GP Super Aeromater that I built a couple years back. A redesign of the kit using Lite Ply would probably give a model of around 6.5 to 7 lbs vs the 9.5Lbs it weighs today.
Build with what you have and build it square and it will be OK.
Don
So what you are saying is, light plywood airplanes come out lighter than a properly designed or modified balsa airplanes, and if they do come out too heavy, just bolt on more power. This type of thinking is wrong on so many levels, especially on little airplanes. Global model airplanes are cool, but far from an optimum designed airframe in terms of weight consideration. You can build the Global Raven in this size with an all up weight of 6 to 6.5 lb ready to fly. two points to remember, horse power is not an antidote for wing loading, and we build to fly, not crash.
Bob
A. I said I wouldn't do it, but I sure would be happy to see a video of the first flight with the mods.
B. "So what you are saying is, light plywood airplanes come out lighter than a properly designed or modified balsa airplanes"
airframe was designed to stand an amount and level of stress not weight, stress is the first consideration here, than you think what kind of material with density[gr/cm^3] will stand this stress.
C. You know decades ago somebody was trying to build a car out of wood instead of steel it ended up being too heavy, they had to use alot of wood to get the mechanical properties of steel.
D. You want to replace 1/8" plywood with 1/8" balsa for a part that carries the whole tail section? why balsa than if you can use cork.
E. maybe the airplane does come heavy, installing weaker parts will make weaker in places were not designed to be weak, safety wise.