Affordaplane

[dgjessing]

I've been thinking of doing a scale model of an ultralight - this one has downloadable plans so it won - http://affordaplane.com/about.html

I established the wingspan at 40" and am scaling / converting all other dimensions based on that. The real thing's fuselage is made of 2" square aluminum tubing, which works out to 1/4" square to scale. I'll make the frame of balsa with plywood gussets and paint it silver.

[fhhuber]

Nice

[earthsciteach]

I've seen these on youtube, but I don't think I've ever seen a video of one flying (the real ones). It looks like a great, affordable ultralight. Cool idea for an rc build!

[dgjessing]

OK, we got the main part of the fuselage and a couple of formica guides for hot-wire cutting the wing halves:

[dgjessing]

Got the wing cores cut, the floor of the fuselage (and landing gear mounting surface) and the motor mount & gusset for same glued in place. Landing gear wire bent and ready to stitch in place.



The plans show the landing gear as being a bit more involved, BUT I've seen pictures of a "real" build with bent steel rod gear that looks a lot like the way I'm doing it . Seem like builders of the real thing make a lot of changes, so I'm going to leave the electric motor exposed and claim that it's a model of the electric version .

[dgjessing]

Progress!



I've put a spruce spar in the wing halves. That will be strong enough given that the wing struts and wire rigging will all be functional.

Built up the curved top of the cowl with a block of foam. I'm waiting for the "DAP" light weight spackling on it to dry. Then the fuselage will be ready to prime and paint.

I'm going to put all three servos on the seat - rudder and elevator literally in the seat, aileron hanging off the back of the seat. A silhouette "pilot" will be sandwiched between the two in the seat.

[fhhuber]

Find an appropriate lightweight doll... chop it up and hide the control system inside

No ugly servos hanging out on your nice scale model.

[earthsciteach]

This build has given me the idea to build a Breezy model. I would LOVE to own one of these!

http://www.airliners.net/photo/1602609/

[dgjessing]

I've painted the fuselage and cut out the "pilot":



To make that silhouette I sat on the floor on different height stacks of books, leaning back at different angles, and my wife took pictures. Printed out the best one and cut it out of 1/32" plywood . So that's ME who's going to be flying the thing!

The aileron servo, which will mount to the back of the seat, is in roughly the same location as the gas tank on the real thing. So if you squint it will look about right .

[road king 97]

I like every thing i see Dave ,going to be a good looking plane and it's different than most. joe

[dgjessing]

Originally Posted by road king 97

I like every thing i see Dave ,going to be a good looking plane and it's different than most. joe

Thanks, Joe

Today I've painted the seat/pilot/servo tray and glued it into place. Also joined the two wing halves with a plywood joiner (6 degrees total dihedral, scaled off the plans). Note the little round "hard points" inlaid in the wing for mounting the wing struts - 1/8" ply cut with a gasket cutter, epoxied into pockets made with a 3/8" forstner bit. And I've laid out the tail surfaces, which will be 3/16" dollar tree foam with 3/16" square balsa perimeters. The ailerons are going to be solid 1/8" balsa.



I'm going to finish the foam parts with a coat of BIN primer, spackle & sand as needed, then a couple light coats of latex house paint.

It sure is easy to accidentally put a scratch in the raw foam parts .

I'm going to use those fiber cloth hinges (can't remember the brand name now). Need to set up to cut the slots for them...

[road king 97]

Originally Posted by dgjessing

Thanks, Joe

Today I've painted the seat/pilot/servo tray and glued it into place. Also joined the two wing halves with a plywood joiner (6 degrees total dihedral, scaled off the plans). Note the little round "hard points" inlaid in the wing for mounting the wing struts - 1/8" ply cut with a gasket cutter, epoxied into pockets made with a 3/8" forstner bit. And I've laid out the tail surfaces, which will be 3/16" dollar tree foam with 3/16" square balsa perimeters. The ailerons are going to be solid 1/8" balsa.



I'm going to finish the foam parts with a coat of BIN primer, spackle & sand as needed, then a couple light coats of latex house paint.

It sure is easy to accidentally put a scratch in the raw foam parts .

I'm going to use those fiber cloth hinges (can't remember the brand name now). Need to set up to cut the slots for them...

For Ca hinges i make a line in the middle of the ca hinge(front and back) with a crayon ,this does two things it lets you see where the middle is when put into both sides and the crayon line wont let any ca in that spot to make a nice smooooth hinge . Ca with out the crayon line drys stiff and then you have to wiggle it back and forth to get it to work right again. joe

[fhhuber]

Originally Posted by road king 97

For Ca hinges i make a line in the middle of the ca hinge(front and back) with a crayon ,this does two things it lets you see where the middle is when put into both sides and the crayon line wont let any ca in that spot to make a nice smooooth hinge . Ca with out the crayon line drys stiff and then you have to wiggle it back and forth to get it to work right again. joe

The issues that arise from CA hinges always come from using the wrong type of CA.

Any gap filling CA causes premature hinge failure plus poor binding of the hinge to the fixed surface and control surface due to poor penetration of the glue (gap filling CA does not "wick" into the hing's fiber coating)

THIN CA only for CA hinges. The thinner the better...

That may bean issue with the foam cores. I have no experience using "foam safe" CA with CA hinges.
You'll still want thin, not gap filling.

[road king 97]

Yes thin ca all the way so it soaks in eveywhere on balsa .Foam is a different story ,i dont know if the make thin foam safe ca so even as we speak iam waiting for ca hinges to dry on a foam plane and i used gorrila glue .I slotted it and then put GG in the slots of one side only with a scrap piece of ca hing then slid my ca hinges in and clamped them ,once dry i will do it to the other side. I could have most likely use the thicker foam safe ca this way but it drys so fast and iam slow. lol I can wait for this to dry and gorrila glue will foam inside if their are any voids. joe

[dgjessing]

I think I'm going to epoxy the CA hinges in the foam, then use titebond into the wood. I'll definitely use the crayon trick - thanks! I'm using a cheap-o Harbor Freight slitting saw in a drill press to do the slots - works great.

I splurged and bought some aluminum tubing to make the wing struts. I'll squish the ends, drill a hole, and bend. Should be a lot easier (and better looking) than lashing little AL tabs onto wood struts (the original plan).

Today I'm painting the wing & gluing up the tail surfaces - it's coming along!

I'm going to be scared to death to fly this thing - it's a heck of a lot more work than my previous hot glue / $ tree foam / packing tape efforts .

[dgjessing]

And it's starting to look like an airplane

[road king 97]

Where you putting the CG at ,1/3 of the wing ? How much positive incidence is the wing at maybe a couple degrees? Looks great I like the open air look and pilot also. If this plane keeps getting built this way i might have to build one myself.lol great job ! Looks like a beaver with no rudder yet tho. lmao joe

[dgjessing]

Originally Posted by road king 97

Where you putting the CG at ,1/3 of the wing ? How much positive incidence is the wing at maybe a couple degrees?

I'm thinking about 1/3 back for the CG, and the wing & horizontal stab are on the same plane. The over-all size, the weight, and the size of the surfaces are all real near the other foamies I've been building, so I'm feeling fairly confident that the thing will behave in a predictable manner. I hope so anyway .

Got the airframe all done, ready for installation of the electric stuff:



I went out looking for some suitable string or wire or something for the rigging cable today and found the perfect thing! At Michaels (the arts & crafts store), I found "Beadalon" bead stringing wire, which is actual miniature braided wire cable. It looks just like the real thing because it is! I got a 100' spool of .018" cable for about $8.50.

[road king 97]

Great find on the wire Dave she looks great. You know i watch about 15 or more builds at a time and yours was the one i was always waiting for a new post . Hope to see a maiden soon . joe

[pmullen503]

That's pretty cool! Looking forward to seeing the finished product.

[Fishbonez]

Wow how did I miss this build I am signed up for the remainder. Looks Awesome and Good Luck

[dgjessing]

Thanks, everybody . It's ready to go:











AUW is 16.3 oz including battery. Wingspan is 40", over-all length 26", height (in the center, sitting on the ground) is 9 1/2". That height is about 1" taller than it would be if exactly to scale, to allow for the bigger than scale 8" prop.

I wish I'd have put some more thought into where the battery was to go. I can spend a minute or two cramming one inside the fuselage, but it's really tight and there is no way to secure it once it's in there. So I've put a strip of velcro on the underside so the battery can hang there exposed.

Taxi tests went just fine; now I just need a dead calm day to fly it .

[road king 97]

Ultrilights are so short nosed because they figure pilot weight in it to get the cg its was going to be hard to find room for a battery . I think it looks great and good luck on your maden Dave . I like seeing something different building and flying for a change and this was a very nice build. joe

[dgjessing]

It flies!

Affordaplane model

Pretty well, too . Flew it 3 times before discovering that the rigging wire through the front down-tube was cutting into the wood, almost severing it .

So it's currently undergoing repair & reinforcement. I'm also replacing the motor... The original was a HobbyKing "donkey" 1550 kv unit. It worked OK today, but running it on a 3 cell battery (which was needed thrust-wise) makes it get pretty hot, and it would no doubt have failed before too long. I just ordered a "Power up" 370 sport from Heads Up - that will be better.

I'm pretty darn pleased

[fhhuber]

Originally Posted by road king 97

Ultrilights are so short nosed because they figure pilot weight in it to get the cg its was going to be hard to find room for a battery . I think it looks great and good luck on your maden Dave . I like seeing something different building and flying for a change and this was a very nice build. joe

One of the reasons I suggested a hollow doll with the battery RX and servos inside.

Looks like it turned out well