Hobby Lobby powered glider build

[hvguy]

After having problems with the mini sparrow, a friend suggested I try something with a larger wingspan for better control. So, thinking simple, I went to hobby lobby and spent $10 on a styrofoam glider, glued it together, laminated everything with packing tape and threw it just to make sure it still flies with all the glue and tape; sure enough, all is well.

Long story short, after I added all the servos/motors/batteries/homemade flap hinges, it was a complete disaster, torque roll and improper motor pitch rolled it and put it in the ground every time and it had NO control what soever.

After consulting a local hobby shop owner, he came to the conclusion that A: the motor was straight, it should be pitched to the left and angled up to counter-act the motor torque and keep the nose up. B: my flaps/control surfaces were too short on the elevator and my hinge idea was garbage; which is when he showed me how to make some better ones. C: needed a little more nose weight, however since I marked the CG before hacking it up, I matched it perfectly when placing the battery.

Now onto Rev 2.
After seeing how he mounts his servos (flush in the wing) I figured it couldnt hurt, why not. I redesigned my rear elevator connector to using just a single tongue depressor (large) glued in place, angled the prop up and to the left and BAM! it flew better, not great... I still managed to wreck it about 15 or so times today. Lots of hot glue was used. It still seems like its hard to control, it barely rolls and the elevator seems to work sometimes. A buddy suggested I was probably flying it stalled the whole time which explained the lack of control. Other times it flew perfectly for 1 or 2 seconds then spiral down and snap the nose off. Maybe im pulling the sticks a little too far? not sure, I plan on checking with the local hobby shop on tuesday.

Now onto my question: Since I dont want to mount the motor in the front in fear of breaking props every few minutes, I have seen motors mounted at the center and above the CG. Would this work better in terms of being easier to fly?

REV 1

REV 2

 

[Basic]

I had one of those. Put on a motor and rudder control and trimmed it glide. I used an 8 gram motor on a pylon. With the motor on it climbed and then glided down with the motor off. After a crash in the wind I rebuilt it and flew it as a flying wing. Adding strip ailerons and a 24 gram motor. I didn't add any reinforcement to it and it broke in flight. Still have the two halves and may resurrect it.

 

[kacknor]

First off, congratulations!

Anytime you can try a new idea, fly it however briefly, repair and fly again that's success. A pusher to boot! Great job. A $10 airframe, craft sticks and hot glue is a fun combination.

OK, the semi-solicited, and always valuable advice, worth every penny you pay for it, to use after spending your next $10.

I think the ailerons are about right, they seem long enough, but shift them outward to the end of the wing. Long wings roll slow. It's better when the surfaces are nearer the ends.

The elevator seems very narrow to my eye. Wider! Embed a BBQ skewer in the elevator to stiffen it if it seems necessary.

Rudder seems narrow too, wider there also.

But all of that is minor and can be flown if the Center Of Gravity (CG) is right. This is gut feeling, but you have two servos, an ESC, motor, mount and a lot of hot glue behind the leading edge of the elevator. Unless you put *ounces* of weight into the nose it's guaranteed tail heavy. That said even though I can't see where the battery is mounted or what size it is.

I'd do this. cut off the nose, hot glue a wood plate (double layer crossed sticks!) on the nose and mount the motor there. Down and right thrust angle! Not much, 3 degrees or so to start with counter clockwise prop spin. Wing servos look OK, but put your tail servos on the fuselage, in front of the rudder, one high, one low. Rule of thumb: For every gram of weight on the tail, you need 5 grams on the nose.

Build it, balance it to *About* 1/4 to 1/3 of wing width behind the leading edge of the wing using the battery. Dig a slot and put the battery there or tape it on good for testing until it's right.

Ask your local hobby shop guy about prop savers and learn to love them. Buy extra props. Buy even more props. Then one or two more just to be sure. (Two blades are cheaper).

Fly!

General stuff: Wing and fuse spars. If it's bendy, stiffen it. Carbon fiber is great! BBQ skewers work too, and are cheap. Glue, but don't over do it, glue weighs a lot. Packing tape works wonders to stiffen and add strength. If it flies with its nose in the air, wing wobbly or tail pitching up and down, add weight to the nose. If it flies pretty good but fast, and noses over with power off, lighten the nose or add to the tail. Read that as shift battery forward or back.

Keep having fun! Flying is fun. Building is fun. Crashing is fun (when it's not too expensive). Learning is fun too

Good luck!

JD

 

[jamboree1]

I'll throw in my 2 cents. Just about every rear pusher I built has the motor staright. a motor at the very back really throws off the CG and takes triple the weight in the nose to compensate. My question is, where do you have the battery at? IF I were to build this glider into powered version and stuck to the rear pusher I would cut off a portion of the canopy, hollow out an area for the battery, esc, and reciever and make esc extensions to the motor.

 

[Basic]

I think you will find the CG for this swept wing should be abut in the middle of the wing root.

 

[kacknor]

I think you will find the CG for this swept wing should be abut in the middle of the wing root.

Indeed. I was stating rote, and wasn't thinking swept wings...

JD

 

[wavetrain75]

Ha! I attempted the same operation on the same glider with the same result. Mine ended up in several pieces in the yard of the house two doors down.

That would be the same house upon whose roof my Bixler decided to make an inverted uncontrolled landing. Thankfully I have good neighbors.