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Old Aug 13, 2006, 09:31 PM
small electrics r BIG FUN
Iowa
Joined Aug 2000
4,297 Posts
Question
BCP wants to climb in ff after changing main shaft/gear

Just recently I installed a new main shaft/gear to replace the gear that was out of round. The old one had the gear lash too tight on one side so it wasn't too loose on the other side. I was careful not to change any linkages , but now the heli wants to climb all the time. The other day I thought it was just the breeze, but tonight it was calm. If I don't hold some down elevator, it wants to nose-up and climb. It's trimmed to hover well. I tried two clicks of down elevator and it didn't change the forward flight tendency to climb. Balance is level.

I did install new flat-bottomed main blades at the same time as the shaft/gear. It's very smooth now and blade tracking checks good too.


Thanks.
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Last edited by Al P; Aug 15, 2006 at 03:57 PM.
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Old Aug 15, 2006, 03:58 PM
small electrics r BIG FUN
Iowa
Joined Aug 2000
4,297 Posts
Any ideas ?
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Old Aug 15, 2006, 04:21 PM
Mom says I'm special...
beafraid8's Avatar
Aurora, CO
Joined Apr 2003
2,562 Posts
Quote:
Originally Posted by Al P
Just recently I installed a new main shaft/gear to replace the gear that was out of round. The old one had the gear lash too tight on one side so it wasn't too loose on the other side. I was careful not to change any linkages , but now the heli wants to climb all the time. The other day I thought it was just the breeze, but tonight it was calm. If I don't hold some down elevator, it wants to nose-up and climb. It's trimmed to hover well. I tried two clicks of down elevator and it didn't change the forward flight tendency to climb. Balance is level.

I did install new flat-bottomed main blades at the same time as the shaft/gear. It's very smooth now and blade tracking checks good too.


Thanks.
Does it nose up and lean back or just try to go straight up? Is your swashplate level with the stick in the middle in idle-up/ stunt mode? With the motors unplugged does everything look normal when you move the controls? Sure there aren't any stripped servos?
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Old Aug 15, 2006, 04:49 PM
Just call me crash.
Joined Jan 2006
1,308 Posts
How new are you at this? Are you adjusting for transitional lift in the first part of the FFF?

Mine has always done this but I thought it was transitional lift as described in the EHBG. Once you dip it forward and begin the FFF, it wants to lift and you back off a little and it levels out. Is that it?
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Old Aug 15, 2006, 05:07 PM
small electrics r BIG FUN
Iowa
Joined Aug 2000
4,297 Posts
Yes, It noses up and leans back. I'll check the swash again in both modes, although I don't fly in idle-up yet. The rear servos twitch, but not the front servo. None slip or indicate any bad gears.

I can be doing large circles or flying straight and level. If I don't give down elevotor, it will nose-up and climb. I'm sure I didn't have to hold down elevator all the time before I worked on it. I just can't think what I did.

I'll go back and look at the swash in both modes.

Thanks for the replies.
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Old Aug 15, 2006, 05:24 PM
Mom says I'm special...
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Aurora, CO
Joined Apr 2003
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Have at it and don't give up!! Post what you find or at least some more potential symptoms...
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Old Aug 15, 2006, 05:58 PM
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Seattle, WA
Joined Apr 2006
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I think it is the flat bottom blades. They will tend to balloon up a lot more than the fully symmetrical ones. Swap out to the other blades. I bet it will fly like it did before.
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Old Aug 15, 2006, 07:00 PM
Mom says I'm special...
beafraid8's Avatar
Aurora, CO
Joined Apr 2003
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Quote:
Originally Posted by flynfrfun
I think it is the flat bottom blades. They will tend to balloon up a lot more than the fully symmetrical ones. Swap out to the other blades. I bet it will fly like it did before.
Good suggestion; it certainly could be, it's been so long since I've flown those! I have a friend that just switched back to flat bottoms and has been having some trouble too...but he's too stubborn to let me trim his heli so we may never know!
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Old Aug 20, 2006, 07:53 PM
small electrics r BIG FUN
Iowa
Joined Aug 2000
4,297 Posts
Well, I found one flybar paddle out of adjustment. I moved that back in line with the paddle frame, then that changed the blade tracking. Now everything is back in line and the ballooning is not as severe.

I really should try the aerobatic enhancement kit. I've been using a stock motor with an 11T pinion for 2s 1250 packs and the flat bottom blades. It flies well but I think I'm ready to try idle-up flying.
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Old Aug 20, 2006, 10:48 PM
Just call me crash.
Joined Jan 2006
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You don't need to do 3D or go to sym blades to benefit from idle up.

Idle up keeps your headspeed constant. So when you float up in a breeze and you move the stick down to bring it back it down, it stays stable because the headspeed doesn't drop.

Just fuse your motors and you'll be fine. I've burned up at least 15 fuses so far, but really like flying in idle up. You spin it up to almost 50%, hit the switch before it takes off and the neg. pitch holds it on the ground. You just move it past neutral when you're ready. It's really not that hard.
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