Convert my old micro heli into a glider (sort of)

[KevinChaa]

Guys, I've been really into rc plane and just to make sure that I'm really into this hobby without spending too much money, I decided to open up my old micro heli and see what I have inside.

Then I came across flitetest. Which make my interest grew into madness. They are really successful bringing newbie like me into this hobby.

This is not my first design. But still, I failed to make it fly. It doesn't have servos. Only thrust. Which means it has only 1 channel.


My goal is to somehow throw this glider at a certain altitude and make it fly with the aid of the motor.
Here is my glider. I called it Midnight.


The propeller is actually the tail rotor from the heli. One of them are the spare part.




(The propeller are placed oppositely because 1 of the motor are rotating oppositely because it's from a heli.)

I know it is a very stupid idea. But I still do have the hope that maybe some ideas from you great guys out there will provide me to improve this glider.

I appreciate all the comments and ideas given by you people out there.
Thank you in advance!


Dimensions :
Wing span : 14 inches
Length (from nose to tail) ： 11 inches
Tail width : 5 inches

 

[Craftydan]

Before you launch that spinny setup . . . have you considered building a pylon?



You could easily make one from a piece of foamboard, slightly longer than 1/2 the prop. Tape the motors in line with each other, then mount it over the wing. You can embed a bbq skewer to keep it rigid. Angle the motors *slightly* down, front to back (front down, back up) to counter the thrustline above the CG.

Have fun with it

 

[KevinChaa]

Wow, this is something new to me. Never seen a pylon before. It actually flies? Forgive me if I'm asking something redundant . But I have never thought about this before.

Still, my motor is very under power. It makes this glider go forward when it's on the ground but not fast enough to lift. I wonder it's my design that is causing it not to fly or it's just plain under power?

 

[Craftydan]

May be a little bit of both. If you give it a toss without power, does it glide? How well does it float? The glideslope sink quickly or does it slowly sink as it travels forward?

Most gliders won't perform much better with power than without -- differently, yes, but not better. A sound, trimmed, aerodynamic airframe can glide without power, given enough of a starting speed. I'd half recommend you take the props off (they'll be running under power anyways) and adjust your surfaces and CG (where the airframe balances, front to back) until you can give it a modest toss and it glides to a gentle landing . . . then start thinking about powering up

 

[KevinChaa]

If I toss it without giving any power it will glide but it will sink quickly but still will land properly. I am thinking of the problem is that the wing is not huge enough to support the weight of the motors and the board. Which makes it sink so fast. (It doesn't have the "floating" characteristic), it will glide, yes but still descend in a very short period of time.

I will take your advice and design a new glider and see how it goes. Will update it here when I have it done. Thank you brother.

 

[Epitaph]

Nice conversion. Have you tried reversing the polarity of the motor to make it spin the other was? Some brushed models allow you to do that. Also, is this from a coaxial helicopter? If so then you can probably get differential thrust to turn the plane a bit with the transmitter, as the turn on coax helicopters is usually by speeding one motor up and slowing the other down. So then power would control pitch and diferential for yaw, turning it into a 2 channel!

Have fun, experimentation is the best way to learn!

 

[Tritium]

This might give you an idea too:

http://www.tmart.com/Electric-Paper...aign=product&gclid=CKep-tSNyr8CFZRj7AodqnoAlA

Thurmond

 

[KevinChaa]

I'm not sure whether it has the differential thrust you're saying because from what I feel from the wind they blow it just feel the same. Yes it is from a coaxial 3ch helicopter.
Also the motor couldn't get their polarity reversed unless I unsolder and solder them reversely I guess?

Haha anyway thanks a lot for the ideas.

 

[KevinChaa]

Wow, this is how I imagine my plane would fly. So I guess now it's the weight that is causing the problem huh.
Very informative. I will re-think and build all over again and see whether it works.

 

[Epitaph]

Are you feeding the 2 motors from the 2 main motor conectons individually? Usually the difference in speed is very little, otherwise the helicopter would just spin like crazy. If it had a "turbo" button, activate it as this was to increase yaw speed and thus give more difference between the 2 motors.

 

[Jnr Kuzi]

You Have a Good Idea, But your Building is a Little sloppy. The wings arent well ballanced, plus thats too Much airfoil for those size wing., the Plane is creating More Drag than Lift.

 

[Jnr Kuzi]

Look at this Video, the guy Has the same idea & he explains his Builds very well, short & straight to the point.

http://m.youtube.com/watch?v=W5v-WcR1MS0

 

[stay-fun]

Cool stuff man! And I like Epitaph's idea a lot: use differential thrust! I've had one of those toys that had differential thrust only, in straight forward flight it would slightly climb, and in a turn it would slightly descend.

A brushed motor will definitely spin the opposite way if the wires are reversed. Although it may wear faster, as the motor isn't designed/used to the opposite rotation; brushes may wear out faster. If the only way to reverse the wires is to solder, than I guess that's what you'll need to do...

I'd say try a bit more proven plane design first. Like try a smaller (50% or so) simple soarer!

 

[KevinChaa]

No, both of the motors are powering from the same circuit board as well as from the same battery. Could you tell me more about the differential thrust? How do I make them yaw a little bit and how would the placement of the motor should look like? left and right like what I did or other orientation?

 

[KevinChaa]

Nice suggestion brother. The plane he made looks very light and simple right? Mine was a little too heavy I guess. It doesn't glide much. Thanks for the heads up. Appreciate it.

 

[KevinChaa]

Thanks man! haha It's just one of my crazy idea when I've been thinking to fix my old heli. If I couldn't fix it, why don't I just convert it into something else that can fly? hahaha

One question though, if I made the plane smaller, but it still carries the same weight like it did. Assume that my plane's design is near perfect and the CG is already tuned at the sweet spot. Will it carry that much of weight and still glide? I don't understand the science here. Does the size of the wing has to do with the weight that it could carry? It should be affected right?

 

[stay-fun]

Watch these on twin engine planes, and learn:

http://flitetest.com/articles/ft-cruiser
https://www.youtube.com/watch?v=fKTtvHWW-JU

Basically, differential thrust means that one motor will spin faster than the other. This will give you yaw (rudder) control, if both wings have one motor. If you're using the control board and transmitter of your old helicopter, the rudder stick will give you this yaw control, as differential thrust is used in a coaxial as well, for yaw control.

Side note: the aerodynamic way that the yaw is induced, is different in these cases though. In a helicopter this is based on differential torque on the fuselage, in a plane it is simply because one side of the plane has more thrust than the other. But the transmitter input for yaw will be the same in both cases.

The reason I suggested to scale the simple soarer down, is because I have a feeling the motors are pretty small for a normal-sized simple soarer. I'm not sure I'm right, though

 

[KevinChaa]

Very very good information you had just provided to me. And yes! It actually give me yaw controls!
When I put it on the ground and control the rudder it does respond to left and right but just very tiny puny turns. But I am happy though.

I think before putting the motor on the plane I should reverse the polarity by soldering them oppositely? Will that bring a lot of harm to my motor?

 

[Epitaph]

The rwo motors will be connected to different pads on the circuit board, though possibly sharing a common ground. When you yaw one way one of the motors should speed un a percentage and the other will slow down the same percentage. Yawing the other way will make the motors speed change the opposite way. It's no good on a coax heli to just havr one blade speed up and the other remain the same as this would imply more total thrust resulting in the helicopter going up as it turns. This comes as an advantage as it doubles the thrust difference and will in the case of the plane give more yaw. The idea is if yawing made one motor speed up 10% and the other slow down 10%, then the difference would be of 20% between the two motors.

If you put the motors too close to each other the thrust differential is unnoticable from that of forward flight, but if you put them too far towards the tips the turn will be very little because of the issue of turn radius along the motors axis, much like the outside wheen on a car has to work faster than the inside wheel. The idea is to find the correct distance from each other on the motors as to not get their thrusts "mixed up", but not too far to the tip. Distamce can be a reason for not.noticing any yaw movement.

Another thing you can look for is a 3 position electrosolenoid to put on the tail rotor circuit to control pitch... You could make it out of the existing motor, but would involve using rubber bands in exact tensile strength. You could also do as the helicopter originally had, and put the tail rotor built into the tailplane so the blades are in line with the horizontal stabilizer in a hole cut in the middle, and the fan turning one way or the other would push or pull the tail in that direction a little to have some limited pitch control...

With a little thought your 1ch plane could become a 3ch plane.

 

[stay-fun]

Nice idea Epitaph! The only thing is, we don't know what kind of coaxial helicopter he has. There are the ones out there that have a tail rotor for pitch control, but I've also seen them with a servo and swash plate. Time for a picture, KevinChaa!

It is very likely the motors already spin in opposite directions as it is now btw. If you have counter-rotating props (one left-hand, one right-hand), you're fine. If you can only find props that fit your motor that spin a certain direction, you'll have to reverse one of the motors, to make them spin in the same direction. Makes sense?