Thanks Jeff and Brian for your comments and encouragement. I'll see about posting an FAQ.bjt4888 wrote: ↑January 8th, 2020, 1:01 pmAir,
Yes, I agree with Jeff. I didn’t mean to discourage your work on gearboxes. Just want to advise you to get clarification and to consider that one of the most difficult parts of gearbox construction is the housing which aligns the gears and shafts. It’s possible that a premanufactured housing might not meet rules as all the alignment is built in. Definitely submit a FAQ on the official SO website.
Also, even if the premanufactured housing is not allowed, it is definitely possible to make one from carbon plate and using small aluminum tubing for bushings. Just make a jig to align shafts and gears during construction. See examples in issues of this type of construction in Indoor News and Views or in Hip Pocket.
Not sure your current configuration will do long duration as, based upon my calculations from your data, your prop is turning at about 100 revolutions per second. However, you have a good start with an innovative idea. So, maybe a different gear ratio, or different prop, or longer rubber, or Etc.
How did you get 100 revolutions per second? It does spin really fast!
I was just jacked that I could get it to fly. I think there is a lot of work on prop and rubber to figure out. The current prop I think is too small but it was an easy way to test small props. Somewhere between the trimmed prop from the kit and the current one is probably where I need to be. I built a longer motor stick last night since I only had a 9" stick on the plane in the video. I can also go down in rubber cross section since it didn't have trouble climbing. With those changes I think I should be able to get 1:15 - 1:30 but won't know until I can get back in the gym.
Since gym time is so hard I built a test rig I've been using to try props and rubber. It's a motor stick on an arm that rotates on a bearing. It flies in small fast circles with no wing! I could only use it to compare different prop rubber combos but didn't know if it correlated to flying until I got in the gym. I now know that if I can get over 30 revolutions in the first 20 seconds its enough torque to climb, current setup is 34 revolutions (I'm guessing on 30 a bit I just know right now I have more torque than needed). I also used the same setup as the flight to figure out the cruise speed that keeps the plane mostly level from the video. 13 revolutions in 10 seconds is cruise speed. Current setup went for 1:08 on the test rig and flight was 1:00 so I also think it gives a good idea of total flight time. Now I can test other setups and then see if it translates to the gym or not. Writing this I just realized I now need to put a longer motor stick on the test rig, ugh! Fun to be able to do something at home! Worst part of WS is waiting to go fly!!