I am notoriously frugal and my first RC aircraft was an Estes helicopter with counter-rotating blades. It was $35 at Menard's and I couldn't pass it up. I crashed it a lot and my flying continued to improve as the bird continued to break. First the landing gear went, then my repaired landing gear, then a part broke that couldn't be repaired. The blade retention screw connected to the top and bottom of the rotor and the bottom plate was broken. I tried CA and it flew for about 30 seconds before it went back to horrible vibrations. I decided the heli was finished, it was no longer worth repairing a 27mhz cheap toy.
But being the frugal guy I am I realized I had some very usable parts:
A transmitter and receiver
A tiny little light battery (marked 3.7v, that makes it a 1s if I've learned correctly)
Two motors with differential thrust from the main blades
One tail rotor that functioned as an elevator for the copter
Thanks to all the great FT designs, I had the bright idea to scratch build a plane with differential thrust instead of a rudder, a tail fan instead of a servo driven elevator, and lots of dihedral for roll control.
So far I've got a KF step wing on a section of tubular(ish) fuselage with twin tails surrounding the tail rotor.
The problem comes from the motors. I can get them to spin the 7x3.5 props at low throttle but they cut out if I try to throttle up. If I slowly increase the throttle I can get them a little over half throttle before they cut out. I was able to make the plane fly for about 10 yards before they cut out in my only semi-successful test. Any application of differential thrust also makes them cut out. They were originally spinning a small gear against a big gear that turned the rotor so they may be designed for less torque and more rpms.
I did reverse the polarity on one motor so they spin the same way (I didn't order counter-rotating props) but it did this before that modification. I think it has something to do with the current draw of the motors tripping an overload circuit in the speed controller circuit. Any advice is welcome, but this is currently on the back burner while I build with better parts.
I have a total of 1 broken helicopter, 1 sheet of foamboard, 2 new propellers, and 2 prop savers into this project. That puts the parts cost at about $5 if you don't count the broken helicopter. My challenge to the show is to do the same thing, only make it work. There are a lot of cheap helicopters on the market and they are bringing people into the hobby. I think using their parts to make a simple plane is a worthy challenge.
But being the frugal guy I am I realized I had some very usable parts:
A transmitter and receiver
A tiny little light battery (marked 3.7v, that makes it a 1s if I've learned correctly)
Two motors with differential thrust from the main blades
One tail rotor that functioned as an elevator for the copter
Thanks to all the great FT designs, I had the bright idea to scratch build a plane with differential thrust instead of a rudder, a tail fan instead of a servo driven elevator, and lots of dihedral for roll control.
So far I've got a KF step wing on a section of tubular(ish) fuselage with twin tails surrounding the tail rotor.
The problem comes from the motors. I can get them to spin the 7x3.5 props at low throttle but they cut out if I try to throttle up. If I slowly increase the throttle I can get them a little over half throttle before they cut out. I was able to make the plane fly for about 10 yards before they cut out in my only semi-successful test. Any application of differential thrust also makes them cut out. They were originally spinning a small gear against a big gear that turned the rotor so they may be designed for less torque and more rpms.
I did reverse the polarity on one motor so they spin the same way (I didn't order counter-rotating props) but it did this before that modification. I think it has something to do with the current draw of the motors tripping an overload circuit in the speed controller circuit. Any advice is welcome, but this is currently on the back burner while I build with better parts.
I have a total of 1 broken helicopter, 1 sheet of foamboard, 2 new propellers, and 2 prop savers into this project. That puts the parts cost at about $5 if you don't count the broken helicopter. My challenge to the show is to do the same thing, only make it work. There are a lot of cheap helicopters on the market and they are bringing people into the hobby. I think using their parts to make a simple plane is a worthy challenge.
