My boyfriend and I decided to build a big ass biplane on the cheap.


Goals

3D Flying Capability

8lbs or less

1 Month build

$150 Budget

Bad Ass



Current Ingredients

Legally obtained political signs made of coroplast

Extreme bi-directional packing tape

Masking tape

CA glue

Clear Gorilla Glue

4 Chanel 72hz radio system, ( 4 standard servos)

Windex

Brake cleaner

A lot of rubber bands.



We have some questions, does anyone have answers?

What should we use for spars? We are thinking of getting carbon arrow shafts – but they seem kind of expensive. Any ideas for other material that would work just as well? Is it possible to get away with not using spars?

What’s a good (and lightweight) way to join the wings together?

What would be a good way to mount the wings on the fuselage?

How much power is needed for the weight of the plane to fly 3D?

Do we absolutely need longerons or are ribs sufficient for the fuselage?

With the bi-directional strapping tape which we are currently using to attach the ribs to the wings – can we use on the fuselage and is there any other place that would be good to use it?

For 3D flying, where should we place the ailerons?

Photos

A) have you flown before
B) have you built before
C) where did you get the plans (if any)

You might check out Oct 2003 and Jan 2004 articles here: http://www.spadtothebone.org/rcreportarticles.html

Keep in mind the site is still a work in progress at updating the old www.spadtothebone.net.

A) Yes, My boyfriend is a competent flier and I just learned.
B) No, buy my boyfriend built an LT-40 and a Bee Gee from kits 9 years ago.
C) We're using plans for a balsa Tiger Moth (for the dimensions): http://www.outerzone.co.uk/planfiles...gerMoth_50.pdf

I would suggest doing one or two smaller spad builds. Power wise you would be going petrol probably 20-30cc which engine alone will set you over budget. Srvos for 3d i would imo would go better than just standard. One per aileron and probably digital metal gears

Maybe a weedwacker conversion for a gas motor? I remember the Bee Gee's from the seventies, man.

Also check out the Ultra Spad Stick at sttb. It is 81" wingspan at 13.5 lbs. You probably will not be able to meet your 8 lb goal with a big plane.

Originally Posted by TheRealFrosty

You might check out Oct 2003 and Jan 2004 articles here: http://www.spadtothebone.org/rcreportarticles.html

Keep in mind the site is still a work in progress at updating the old www.spadtothebone.net.

Thanks "The Real Frosty".
Good reads.

Originally Posted by aspeed

Maybe a weedwacker conversion for a gas motor? I remember the Bee Gee's from the seventies, man.

Scrubmonkey,
Aspeed,

I'm hoping to get a beefy electric motor, from Hobby King, I'm seeing some that might work: http://www.hobbyking.com/hobbyking/s...0KV_2400W.html for $45 with 5+kg of thrust, combined with a battery and speed control might put me a bit over-budget, but I think I'd like to keep it electric so It doesn't shake apart.

Originally Posted by TheRealFrosty

Also check out the Ultra Spad Stick at sttb. It is 81" wingspan at 13.5 lbs. You probably will not be able to meet your 8 lb goal with a big plane.

I'm hoping that if I keep it really simple and sacrifice strength for weight the 8 lbs goal might work: the wings are single sided and are ~ 3lbs for both (without any spars), I'm hoping the coro skin of the fuse will be strong enough to just use some coro ribs to complete it. If I miss the 8lb goal I want to be at least close. Any ideas on how to lighten things up?

profile fuse with a piece of aluminum angle for stiffening?

I guess other lightening ideas depend on how much you want it to look like a tiger moth.

Originally Posted by TheRealFrosty

profile fuse with a piece of aluminum angle for stiffening?

I guess other lightening ideas depend on how much you want it to look like a tiger moth.

Therealfrosty,

A profile fuse could do it, that was my boyfriends initial idea. I think it makes too much sense and is too easy for this project though. It's more challenging with a full fuse.

Maybe I'll try to go longeron-free with the fuse. Do you think that'd work? I don't know about not doing leading edge wing spars though, It's pretty rigid with the curve of the coro and carbon arrow shafts wouldn't add too much weight though. Maybe I'll see how rigid it is after I've got the top and bottom wings rigidly connected.

If it's any help, most coro fuses that I have seen don't use longerons. They usually just use a few formers. See this 1/4 scale Fokker D-VII Build at spadworld.net. The fuse stuff starts on page 2.

frosty

Today we got the fuse box re-cut out ( the first cut was too small), all four wings are mostly built. The weight should be at around 6lbs but may be slightly less when the fuse is cut. Hopefully we can make more progress this week and determine what the weight will really be so we can order the appropriate motor (I want ~2lbs more thrust than the weight of the plane). Thanks for all the advice thus-far, we definitely need all we can get with our first dive into SPAD. We threw together the airplane to see about how big it will be; my boyfriend is pretty happy about it!

Youre going to have ALOT of problems with the fuse twisting unless you get some serious re-inforcement. Especially if you plan to do 3d