Why you should not run an MP Jet planetary gearbox in reverse......
Decided to give a different motor a try in a pusher model and had a Hacker B20-12L on an MP Jet 3.8:1 planetary gearbox available.
I reversed the motor direction, slapped a 7x4 APC prop on it and checked everything out. Handlaunch and 2 complete circuits before the prop came fluttering down.
A deadstick landing and I find the housing had unscrewed itself due to the prop torque. It was secured but somehow came loose. In a normal rotation (for tractor use) this would not have made a difference. However as the reverse prop torque tends to 'unscrew' things, use as a pusher should only be attempted if you are sure things are tight and secure.
I lost all the planetary gears and assume I need to buy a complete new box.
Oh well - live and learn I suppose.
You have been warned
Just FYI, you don't need to throw away the gearbox. I'll have the pinions in stock when we open the shop next year. I'll be back in Japan early March, so send me an email and I'll get them out to you if needed. Shipping will only be about $2 - the set of gears and washers will probably be priced around $5.
Air Craft Japan
|Category||Thread||Thread Starter||Forum||Replies||Last Post|
|An Apology.......(or why you should not bite off more than you can chew)||Steve McBride||Electric Plane Talk||16||Jan 24, 2003 09:42 PM|
|New MP Jet Planetary gearbox for speed400 3.33:1||Gerald||Aircraft - Electric - Airplanes (FS/W)||3||Nov 11, 2002 11:45 AM|
|AF 010 with MP jet planetary gearbox ?||dvint||Power Systems||0||Nov 07, 2002 03:51 AM|
|Durability of MP Jet planetary gearbox ?||dvint||Power Systems||1||Apr 08, 2002 07:39 PM|
|FYI - Lesson Learned with MP Jet Planetary Gearbox||Steve McBride||Electric Plane Talk||1||Sep 19, 2001 05:41 PM|