RunRyder - Stripped the Crown Gear on my P-Gasser

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Gasser Model RC Helicopters > Stripped the Crown Gear on my P-Gasser - AGAIN!

jackheli
Elite Veteran
Location: Vancouver - Canada

Well, this time I got it! It was right at first spool up.

I am positive the mesh was right this time. There is no binding WHATSOEVER on the tail.

What is causing this? I am very frustrated and tired of my Gasser at this point.

Anyone who has never made a mistake has never tried anything new - Albert Einstein

12-31-2007 12:11 AM

FloridaHeli
Heliman
Location: jacksonville, florida

I've not had a problem as you describe with my Predator. I literally push the tail boom transmission bevel gear down in to the 70Tooth beveled drive gear as tight at possible. then tighten the screws down. It lasted until I had a glitch today and the heli buried itself with negative pitch. The only part that broke was the 70T gear.

I can fix the gear but now have to find the source of the glitch. Was using a JR 9303 with XPS Tx module and Rx on 2.4 Gz.

Good luck.

This hobby is WAY too expensive!!

01-12-2008 02:48 AM

lperagallo
Senior Heliman
Location: Westfield, Indiana, USA

Floridaheli,

How do you know it was a glitch? With the 2.4 it is almost impossible to get a glitch. Most common problem has been power. If you drop below 3.9 volts the RX will brown out and you will lose control. If you had failsafe set did the throttle come down to your setting? If it did, then it's possible you may have had a problem, but highly unlikely it was a glitch.

Which RX are you running? There is an issue with early AR9000s. See the Spektrum site about that issue.

But power has been the biggest issue.

Lou

Bergen Intrepid EB, G-26, 720mm; Bergen Turbine, Wren MW54; Raptor 50V2, OS50-Hyper

01-12-2008 06:21 PM

FloridaHeli
Heliman
Location: jacksonville, florida

Lou

You may be right about the low power, it acted like a glitch; no control.

I've had the low volt problem happen before due to a bad battery on my Rapter 50 with XPS 2.4 system. Took awhile to find it as the Rx LiPo battery took a charge to correct voltage but only dropped low after a few minutes in the air. Found it by stroking the servos for several minutes on the ground while watching the voltage on the GV-1 and the indicator light on the Xtreme Power Systems 10 channel Rx. It went from solid Green to orange and red; meaning loss of signal due to low battery.

You brought up a good point. I'm going to check the battery on the Predator that I mentioned above and put a 3 amp load on it. I'll bet I have another battery issue.

I'm not sure failsafe will work with a low power problem. However, my failsafe was not set to lower the throttle. It is a bit difficult to do that with the XPS Rx; got to push buttons and watch blinking lights. Not had much luck. They now have a programmer that can do it on a computer. I'm thinking of getting one.

My 2.4 system is a XPS as noted above with a Tx module that fits in my JR9303.

Thanks for the comments. I think you have put me back on the right track.

Tom

This hobby is WAY too expensive!!

01-30-2008 03:08 AM

Excalibur
Senior Heliman
Location: Destination: Earth

Sounds like it might be a good time to put a "Jewel" generator from Raja on-board. Anything above idle gives you a solid 5.4V and maintains that voltage during flight. It is absolutely worth the cost, and will be one less thing to worry about (low voltage). I wouldn't fly without one now.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore

01-30-2008 06:29 AM

bellecrank
Veteran
Location: Canada

Jackheli,

Something must be stopping the tail gears from turning, which in turn will strip tghe crown gears.

I had the same thing keep reoccuring on a MinAir heli I once had - the cause proved to be a bad bearing that supported the front pinion. It woudl heat up and seize. When it did, it would stop the tail from turning and strip the crown gear.

01-30-2008 07:21 AM

jester4
Veteran
Location: Brampton, Ontario (Flyin' outta Mississauga)

I have to agree with bellecrank. If you are stripping that many crown gears, there must be something else going on. I think his suggestion for looking at all the tail mechanics is a good one. Would a one-way bearing issue cause this as well maybe?

01-30-2008 04:24 PM

jackheli
Elite Veteran
Location: Vancouver - Canada

I disassembled the whole tail assembly and boom and found nothing. Got a knowledgeable buddy to inspect the build and he also found nothing. The mesh was perfect.

I suspect it is the gyro which is aggressively applying pitch with no dampening, so I am replacing my 720 gyro with a 611 and run it in FAI mode.

Also, will try richening the low needle a bit and see if that helps: maybe there a bad vibration going on due to a lean winter setting...

Anyone who has never made a mistake has never tried anything new - Albert Einstein

01-30-2008 05:29 PM

mcfast
Veteran
Location: Canada

Run your 611 in 3D mode it has a bit softer stop.

01-30-2008 05:36 PM

oldfart
Elite Veteran
Location: Vancouver, Canada

jackheli

Your gear mesh etc. may be perfect. But if there is a bad bearing, one that under load (turning at speed) can heat up and seize, then it will cause the pinion to strip the crown gear. On inspection later-the bearing nay turn quite freely.

It can also be a problem re: the delay setting on your gyro. That is why a lot of top 3D flyers use the FAI setting and adjust from their with their 601/611's.

01-30-2008 08:48 PM

jackheli
Elite Veteran
Location: Vancouver - Canada

I looked at every single bearing on the tail setup and none of them seem to catch. They all looked ok, so I am hoping a different gyro and better needle settings will do the trick.

Anyone who has never made a mistake has never tried anything new - Albert Einstein

01-30-2008 08:52 PM

AceBird
Elite Veteran
Location: Utica, NY USA

Quote
I was wondering how to do it without being able to remove the supports from the TT. http://www.runryder.com/helicopter/t365647p1/

Jack, this great idea could result in abrasive particles getting into the bearing. It only takes one tiny particle to lock up a bearing. I can’t for the life of me figure out why the plastic bearing support would be larger than the id of the boom. The torque tubes are supposed to be identical and the difference in ID between the standard boom and the HD boom is made up by o-rings. You definitely had a tolerance problem. I would have measured the parts and corrected the one that was wrong. If the boom was wrong you could have problems with the OD also.

Now is the stripped crown gear related? Who knows? Can you carefully take the box apart and take some close up pics of the parts? It would be nice if the pics were untouched parts but by now you probably have cleaned them.

Quote
Oh.. but I REALLY think I suck at building this gasser. No sarcasm here... That is why I am giving up. It is clearly not for me. http://www.runryder.com/helicopter/...1/?p=2970062#RR

You succeed by telling yourself you can do it. You will never succeed if you tell yourself you can’t do it. BEFORE you try to fix this next problem change your attitude. You can do it but not if you think you can’t.

Ace
What could be more fun?

01-31-2008 12:44 AM

FCM
Elite Veteran
Location: Back in Blighty!

If in any doubt about bearings, change them as they cost next to nothing and can go wrong for no obvious reason.

If a gyro or tail servo is stripping gears then look at the gear mesh/alignment rather than the gyro.

Paul.

01-31-2008 03:31 AM

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Gasser Model RC Helicopters > Stripped the Crown Gear on my P-Gasser - AGAIN!

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