scratch83

i am building a 4channel smaller airplane from scratch(hi wing,4 degree dihedral,hi lift low drag airfoil)..the fuse length is 30 inches,and i am planning a 44 inch span with a 6.5 inch chord(which works out to about 286 sq inches)..(balsa rib wing with 2 horizontal spruce spars 1/3 chord,leading edge stock((balsa)),trailing edge stock((balsa)),and aileron stock)...my first question is this:how long should the ailerons be?second is:would a .25 os max la be too much for this model?ive been told on here that a .25 is waaay too much for this model..a local hobby store owner(avid builder and flyer)says a .25 is just right for this model as a trainer(and a .30 is gonna be good for more sporty flying)..im just tired of getting different feedback from different people...please help!!!!!!


scratch

Stick Jammer

I would make the ailerons full length if that is what you meant. 3/4" to 1" wide if this is what you meant. What do you think the final weight will be? An LA .25 doesn't sound like too much to me as long as it balances out. As a general rule of thumb, go with the biggest engine that doesn't upset the CG, you can always throttle back.

BalsaBob

My Feedback: (24)

The .25 sounds like the right size. A good way to help determine the engine size for a scratch built project is to check the engine recommendations for existing kits ... that are similar to your design. With the hundreds of kits that are out there today, chances are there is a (similar) existing kit version of your design. Bob

scratch83

sounds good to me..i was being told that i would need a .049-.060 or it would be a nasty flying model...thought it sounded kinda bogus,but you never know....do you think my wing assembly is sturdy enough for this kind of wing loading(i mean i have spruce stringers and 1/16 thick balsa ribs,i cut a 90* birds mouth in the leading edge of the ribs to accept a 1/4x1/4" balsa square stock and i will sand it to shape,also 1/4x1/4" square balsa trailing edge stock for aileron mounts,and 1x1/8" aileron stock)..i plan on using the fabric hinges,does anyone oppose this method??

scratch

SST

My Feedback: (2)

For a .25, you may need to D-tube the wing. As for engine size, I'd be more interested in matching power to wing loading...How much will it weigh?

DBCherry

My Feedback: (4)

I'd be curious to find out anticipated weight as well. I've seen 44" span models flown with .061's, and I've seen them flown with .25's (even .40's), but it depends on the design and weight.

4" of dihedral makes me assume it's a high wing trainer type aircraft.
Dennis-

scratch83

sure is a high wing trainer type...whats d tubing and how do i accomplish this?im contimplating building a more sporting wing(maybe foam) for later,i dont know how much it will weigh when finished,i guess ill find out!!then ill go from there and chose the correct engine for the weight.....whats a good weight for this type of airplane for a .25???

thanks,scratch

Tall Paul

D-tube leading edge.... also works well on trailiing edges..
http://www.angelfire.com/indie/aerostuff/dtubes.htm

scratch83

hmmmm..i think i might sheet the ribs and leading and trailing edges in 1/16 sheet...is this enough reinforcement??

scratch