L Edge
Master member
While adding 4 servos to evaluate leading edge and tail flaps, weight and drag forces required me to try to replace the motor for increased thrust. Due to covid-19, supplies are out of stock. Who knows when they are in stock again, so decided to take a chance of improving thrust by modifying prop using present motor.
Back, many moons, when my son and I moved up to Formula 1 pylon racing, they had only wooden props. In order to be in the racing pack, you cut, shaped, sanded your prop so it gave max thrust at 21,500 revs so it would unload in flight and do +26,000 rpms. Safety was very important so you were very careful in what you did to the prop.
Now move to present.
2 conditions- have 9" width between bulkheads and with landing gear, 10" prop would hit ground.
If I hover with 9" prop and different pitches, it takes almost full throttle to do it. Esc cuts out or motor overheats. So no go.
Since RPM's are very low, decided to modify a APC composite 10 inch prop.
The 9" prop is super-imposed over the 10". What if I cut the 10 down to 9 to fit in and see how much of an area I pick up to improve the thrust(if motor can take it). You don't need a computer to figure out the area lost > 9 is less that area gained < 9.
Since both props were place together, made the cut for 9" on both sides. Rounded the leading edge and sanded.
Next, the blade and hub were balanced until it was perfect. If you don't, vibrations will destroy your electronics.
Present Esc was 18 amps, so move up to 20 amps and no cutoffs or overheating of the motor. Installed, and now the plane hovers at 82% of throttle and added enough thrust so i can explore system. And never stand in the plane of the prop while checking it out.
For those who don't understand balancing props, here is a vid.
Back, many moons, when my son and I moved up to Formula 1 pylon racing, they had only wooden props. In order to be in the racing pack, you cut, shaped, sanded your prop so it gave max thrust at 21,500 revs so it would unload in flight and do +26,000 rpms. Safety was very important so you were very careful in what you did to the prop.
Now move to present.
2 conditions- have 9" width between bulkheads and with landing gear, 10" prop would hit ground.
If I hover with 9" prop and different pitches, it takes almost full throttle to do it. Esc cuts out or motor overheats. So no go.
Since RPM's are very low, decided to modify a APC composite 10 inch prop.
The 9" prop is super-imposed over the 10". What if I cut the 10 down to 9 to fit in and see how much of an area I pick up to improve the thrust(if motor can take it). You don't need a computer to figure out the area lost > 9 is less that area gained < 9.
Since both props were place together, made the cut for 9" on both sides. Rounded the leading edge and sanded.
Next, the blade and hub were balanced until it was perfect. If you don't, vibrations will destroy your electronics.
Present Esc was 18 amps, so move up to 20 amps and no cutoffs or overheating of the motor. Installed, and now the plane hovers at 82% of throttle and added enough thrust so i can explore system. And never stand in the plane of the prop while checking it out.
For those who don't understand balancing props, here is a vid.