Originally Posted by
Henning
I flew for the first time today with the new upgrade gear set for the V4. What a difference. It is really quiet compared to the old gears. My flying buddy was flying with the V4 and old gear set and it sounded like two different propulsion systems.
Will the next generation gears be helical?
Br,
Henning
Hey Henning,
The next gears probably won't be helical.
There are several things that contribute to quiet gears:
1/.. Tooth to tooth composite error
2/.. Total composite error
3/.. Tooth contact ratio
4/.. Tooth surface finish
The upgrade gearsets are cut in a single setup on a brand new Swiss CNC lathe. This means there is effectively no position tolerance between the center bore of the gears and the pitch circle diameter of the gear mesh, which is responsible for the total composite error. There is also almost no "clocking" error between the teeth as well, which causes tooth to tooth composite error.
The upgrade gearsets are also "lapped" as a matching set, which creates a very high-quality tooth surface finish.
Based on the inspection measurements Mike is now getting with the upgrade gears, the AGMA quality level is now 12 plus.
As far a tooth contact ratio is concerned, helical gears would help, however, the gear tooth profile was originally modified to maximize contact ratio and eliminate involute profile undercutting. (which can happen with pinion gears that have less than 17 teeth ...) This was done by radially shifting the pitch line of contact away from the pinion gear towards the planet gear.
This modification has given us most of the benefits that we could expect gain by using helical gears, so it probably doesn't make sense to increase manufacturing complexity by switching to them.
Brenner ...