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450 Class Electric Helicopters 450 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 12-30-2009, 07:11 PM   #1
WREX450
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Default What the...Nose Drops if FFF???

Maidened my 450 pro and ran into a problem I've never seen before? I used a swash plate leveler and corrected for CCPM interactions during the build (I thought). Due to my ESC and AR9000 being mounted outside and towards the back, it was tail heavy. I figured this would be the case, so no problem, I'll correct the setup to get the correct CG.

The surprising issue to me was that during FFF the heli progressively drops its nose and I have to give significant elevator to correct as the speed increases. I figured being tail heavy this would be the opposite? The only tendencies during hover are for the heli to creep straight backwards. Any chance the shape of the canopy has an effect at high speed? I had a 450v2 and 500esp before and never had the issue. Tonight I'll recheck pitch, swashplate, interactions and correct the CG. By the way, what a great flying heli, although my 25c flightmax batteries seem way underpowered now.

Any help diagnosing this is appreciated!
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Old 12-30-2009, 07:23 PM   #2
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fwiw..
Be sure the paddles are correctly aligned...Yes, the horzontal fin/canopy definitely have an aerodynamic effect....
forward flight in a heli involves a lot of changing dynamics with speed...If you can, get a more experienced pilot to fly it..what you are seing may be normal for the fins/canopy/paddles you have on your heli...One possible fix would be heavier paddles/flybar weights, but that will come as a loss of cyclic snap.
Let us know how you do...

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Old 12-30-2009, 10:05 PM   #3
WREX450
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Thanks for the help, I checked and the swash was slightly out of spec, but nothing extreme. Paddles are good too. Stupid question, but your setting the CG right on the flybar right? I just pick it up by the flybar and watch the skids as I rest it on the table. I check front to back and side to side. If its hitting the rear part of the skid, I would be tail heavy right? Just double checking Im not missing something obvious here.
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Old 12-30-2009, 10:11 PM   #4
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I will be interested to hear how this turns out. The little bit I know about helicopter aerodynamics tells me that this is impossible.

I'm not doubting what you report, I am just very interested to hear what the cause turns out to be.
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Old 12-31-2009, 12:55 AM   #5
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I always watch newly setup helis for rise or drop in FFF and trim it out.. only takes a click or two.
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Old 12-31-2009, 08:12 AM   #6
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could it be the swashplate not travelling level throughout the travel. I've had similar happen on my King2 once upon a time.

--N
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Old 12-31-2009, 08:14 AM   #7
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I'd take a closer look to make sure the paddles are level. This is what comes to my mind as well. If the paddles are not level then during fast forward the wind coming accross might be pushing on it and inducing cyclic input when you don't want it. Paddles are the usual culprit in pitchy flight.

Also remember to check CG with canopy on.
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Old 12-31-2009, 09:13 AM   #8
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my SE does that if I go fast enough.
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Old 12-31-2009, 01:48 PM   #9
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Ok when it rains it pours... Went to spool it up and the motor won't spin at all???!! I have it set on slow start, all stock set up with the 450m. I pulled the motor and it is very difficult to turn with the power on or off. I can manually get it to turn, but with moderate resistance. The motor tries to start but will make a 1/4 revolution before hitting resistance and stopping. I fiddled with it for a while and once it gets a few rpms, it appears to lose the resistance and run just fine. It does this in or out of the heli. Only problem as soon as i stop it, the resistance re-appears??? Nothing has fallen it, nor have any of my DX7 settings changed. Anyone know how to open the motor, I can't find any screws. Ran fine all day yesterday, came down cool to the touch and never been wrecked. I need a beer..

Last edited by WREX450; 12-31-2009 at 01:52 PM.. Reason: Add details...
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Old 12-31-2009, 02:45 PM   #10
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make sure u dont have a screw stuck in one of the motor vents
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Old 12-31-2009, 02:46 PM   #11
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redo ur esc settings
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Old 01-01-2010, 06:25 PM   #12
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pitch up or down in FF can definitely be caused by "collective" pitch built into the paddles. What I mean is, with the flybar level and the swash level, the paddles both have a bit of up/down pitch. You can see it by looking end on and comparing the paddles to the flybar cage.

In hover, it wont have any effect. But in FF, if the paddles are pitched up, then the advancing paddle will lift more than the retreating paddle. Dissymmetry of lift due to the FF airflow. Precession causes the flybar "disc" to respond by lifting up in the front. which in turn causes pitch up of the main rotor. If the paddles are pitched down... the opposite happens, and the main rotor will pitch down.
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Old 01-05-2010, 11:01 PM   #13
WREX450
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Finally got my replacement motor installed and it must have been the flybar paddle. The swash was only slightly out of spec, but one flybar paddle had definitely moved. Corrected it and all is well, THANK YOU !!!!!!!
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450 Class Electric Helicopters 450 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.

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