Thread: Discussion Another coaxial F3P plane
View Single Post
Old Mar 30, 2011, 01:50 AM
Kimmo Kaukoranta is offline
Find More Posts by Kimmo Kaukoranta
Registered User
Kimmo Kaukoranta's Avatar
Tampere, Finland
Joined Apr 2004
109 Posts
I do not think the idea is totally new. Although it is not very common, something like his has been used on some applications before. So I do not think it could be patented.

We did the slip rings from some brass tubing, soldered a wire inside and had some insulator pieces cut between the rings from fiberglass board using a CNC mill. The carbon brushess came from some brushed motors (speed 300 I think).

Yes a geared motor does have some noise, but the good thing is You get a better audible feedback when you increase or decrease the throttle. Our planes are getting lighter and lighter every year, the amount of power, and thus also the noise will decrease. The noise is not as bad in reality as it seems on some of the videos.

There are things that can be done to suppress the noise, like building a totally enclosed gearbox. I have not explored those options further (yet). With the open gearbox, it is better not to build any of those 45-degree depron pieces on the nose, those will amplify the noise a lot

Also the proper mesh of the gears, the modulus (size of the teeth) etc affect the amount of noise. The geard ratio and the RPM affect the base frequency, I try to stay away of very high ratios because the pitch of the noise becomes very annoying. Try a >10.000 kv motor on 2 cells in a 15:1 gearbox and you know what I mean

With a belt drive you would need a very small toothed belt to prevent it from slipping (that is actually available). Other problem is getting large enough reduction from one stage. But certainly it could be done.
Kimmo Kaukoranta is offline Find More Posts by Kimmo Kaukoranta
Reply With Quote