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01-13-2006 05:57 AM  13 years ago
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pulsar110

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USA

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Pitch up in FFF
My trex tends to pitch up in forward flight. Its probably the blades, or at least my bigger helis do with bad blades. Im currently using MS1052T the 315mm woodies. Wondering what you gurus are using now a days with all the newer blades out. Would like to get rid of that tendency if I can.
Fly it like its a rental...
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01-13-2006 06:20 AM  13 years ago
Lorents

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Oslo, Norway

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Bad paddle alignment could also make it pitchy in FFF.

What comes around goes around.
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01-13-2006 06:21 AM  13 years ago
pulsar110

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hhmmm now theres a couple good thoughts. now that i think about it i still have to old style head block on it with 1 o ring on each side too.

looking at it the paddles look good actually.
Fly it like its a rental...
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01-13-2006 06:34 AM  13 years ago
cody69

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adelaide ,south australia

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The new 315mm pro blades (woodies) Tend to pitch down on my heli. So they might solve your pitching up problem. They feel a bit more stable in flight compared to the older white ones.
I run 2 orings each side with the larger spacers to make it firmer.
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01-13-2006 07:17 AM  13 years ago
cody69

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adelaide ,south australia

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Trim in hover is fine, the heli climbs straight up when applying full power. Balance is ok .

With the white woodies on it pitches up...

My raptor falls in fff as well. I did read some where it was somethng to do with the rear fin, but not sure.

The new pro blades are better than the older white woodies no matter what. Worth the extra $1.
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01-13-2006 12:42 PM  13 years ago
Rickenbacker

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Örebro, Närke - Sweden

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Check your center of gravity. On the T-Rex it should ideally be just a tiny bit in front of the main shaft.
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01-13-2006 01:56 PM  13 years ago
Chris True

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St. Mary's City, Maryland

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One other thing to check - ball links and particularly the Y arms connected to the swash. MY old X started doing the FFF pitch up thing and it was sloppy Y-Arm ball holes. Swapped those out and the pitchup went away.
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01-13-2006 02:22 PM  13 years ago
Chugga-bug

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London UK

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Am I missing something here??

I always thought that pitching up in FF was due to the rotor disc acting like a wing..i.e. more airspeed over the disc = more lift.
"Up in smoke... that's where my money goes.."
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01-13-2006 02:40 PM  13 years ago
Lorents

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Oslo, Norway

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The way your rotor head is configured can affect how much a heli will pitch up in flight. I once tried out lots of different paddles on my old Nexus and with yellow KSJ paddles it would pitch up real bad in FFF.

What comes around goes around.
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01-13-2006 02:54 PM  13 years ago
Hoverdown3K

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Rochester, New York

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Pitching up in FFF is something to deal with, depends on how bad, I have very slight pitch up on my Rex, but you can feed in a little less collective and give some nose down to control the pitching in FFF-= I know there is Money in RC helicopters. I put it there=-
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01-13-2006 03:08 PM  13 years ago
AnnihilaT

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The Netherlands

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1 oring on each side? Thats at least one of your problems. You need a stiffer head. Add another o-ring on each side and chances are your problem will be greatly improved if not solved.



A day without sunshine is like, well, night.
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01-13-2006 03:54 PM  13 years ago
pulsar110

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USA

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MFIS thats all my old head was designed for. I havent posted on this thread for some time and havent read it much either. Just started flying it alot more and decided that I wanted it better.Fly it like its a rental...
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01-13-2006 04:43 PM  13 years ago
spork

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Mountain View, CA

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Pulsar,

I agree with the folks that are suggesting more head damping. I had a fairly severe problem with the heli pitching up in FFF. Mine was not the typical problem where it would pitch up more the faster I flew. In my case it had a bad tendency to want to make an abrupt hockey stop - typically after coming out of a turn. I tried a whole bunch of things. When I stiffened up the head damping it was cured. If yours is the more typical pitch up you might want to look at your paddles too. Some people put a little negative pitch in their paddles to cure this. The downside is that it gives more "pitch up" when flying inverted.

Also, make sure the delta-3 offset on your flybar paddle linkage is on the correct way. It's really easy to get this backward. This will tend to make the flybar divergent.

Good luck.

RC
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01-13-2006 05:04 PM  13 years ago
AnnihilaT

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The Netherlands

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Pulsar,

Is that a 450x version one? Its been so long i cant eve remember how many o-rings those had but i do remember needing to stiffen it up to get decent performance in FFF. Especially coming out up a very high stall turn it would always want to pitch up as it gained all that speed.

Anyway its a 5 minute job to stiffen it up so just give it a shot and let us know how it works out for you




A day without sunshine is like, well, night.
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01-13-2006 05:32 PM  13 years ago
pulsar110

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USA

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spork

thats exactly what i want to cure. this is the 450x version that came out a little over a year ago. i have had a new head laying around for it just hadnt put it on. in the old one there is 1 o ring on each side. the new one i have has 2 on each side. ill put that one on and see how it behaves. thanks for the ideas guys.
Fly it like its a rental...
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01-15-2006 01:00 AM  13 years ago
skyhawk

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belvil mich

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stiffen up the head-----
Could you explain how to stiffen up the head.
This is a factory assembled unit.
Are you talkin' sqeeze the dampners?
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01-15-2006 02:46 AM  13 years ago
spork

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Mountain View, CA

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Could you explain how to stiffen up the head.
This is a factory assembled unit.
Are you talkin' sqeeze the dampners?
Perhaps others could offer better info on this. I bought mine used, and it came with the blue aluminum head. It did have more slop than seemed right, so I took it apart. In my case I found it wasn't actually assembled properly. I re-arranged some stuff and put two O-rings on each side. I guess some people put up to 3 o-rings on each side but I can't imagine how you could fit 3 per side on my head. I believe some use silicone fuel tubing in place of the O-rings. I may try that myself if I can find tubing with a real snug fit.

At least on my head there are two sources of play. The blade grips wobble a bit on the feathering shaft, and the feathering shaft teeters in the main head unit. The O-rings dampen the latter. In my blade grips I can fit two big bearings, one small bearing, and a spacer (between the two big bearings. When all that stuff is in there and configured correctly the wobble of the blade grip on the feathering shaft seems within reason. I'm considering finding a longer feathering shaft and adding another spacer between the big bearings. This should reduce the wobble further (if such a shaft can be found).

RC
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04-19-2006 02:08 PM  13 years ago
whtbronco

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Winchester, Virginia USA

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I'm having the same problem, pitching up badly in FF, fast or slow. It did this inverted as well as upright previously. I swapped out the crap stock wood blades for a set of carbon fiber blades which did nothing to change the symptoms. I have added a 3rd O ring to each side of the head on my 450XL HDE. This cured the inverted issue, it tracks very well inverted now. So I find my self flying inverted a lot which is okay. However, it pitches so much in forward flight I don't need any aft cyclic to go through shallow turns and only a touch for tight turns and inside loops. If I leave the fore/aft cyclic alone flying about 200' across the field upright will cause it to climb by about 100'. So I hold forward cyclic all the time and end up porposing a bit when flying straight and upright.

It hovers just fine.

I'm confused here, oh well that's nothing new LOL.
Chris Wish I was flying!
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04-19-2006 02:42 PM  13 years ago
spork

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Mountain View, CA

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Just pulling this out of thin-air, but I would check my overall balance. Are you a little tail-heavy? How about your chopper?
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04-19-2006 02:46 PM  13 years ago
whtbronco

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Winchester, Virginia USA

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Tail heavy me yes, heli no LOL. I have checked it repeatedly. It balances right at the flybar.Chris Wish I was flying!
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