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Home✈️Aircraft🚁Helicoptere-BladeOther › Main rotor pitches forward and to one side instead of straight forward
09-06-2006 07:59 PM  14 years ago
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uogecko

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Evanston, IL

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Main rotor pitches forward and to one side instead of straight forward
Hi everyone - I'm still learning how to operate my Blade CP - in fact, I'm not sure mine is capable of true flight - I think I got the "crash only" model. That'd be the E-Flite Blade CO.

Anyway, keeping in mind that I have crashed more than once and replaced parts - got it flying again, I've noticed that when I push the collective forward, the main rotor pitches down at the nose and significantly to the left. It should pitch down in the front and up in the back. How do I go about troubleshooting this? I'm able to fly it as is but I have to compensate for this issue by pushing the collective forward and to the right.

Thanks!

Gabriel
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09-06-2006 08:35 PM  14 years ago
bbeverlie

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Hudson,New Hampshire.USA

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I may be missing something here but I think your referring
to cylic. When you advance the collective you are really
raising the head speed and blade pitch unless in idle up
then you are only affecting pitch.

You should check to make sure your swash plate is level
check out http://www.bladecprepair.com for a how to on doing this.
AMA#846952
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09-06-2006 08:57 PM  14 years ago
playfair

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Rochester, NY

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You may be seeing "gyroscopic precession", which is a search in itself. Basically, the rotor is a gyroscope, and the control inputs must act 90 degrees upstream in order to have the desired outcome.
The sky is our canvas
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09-07-2006 01:59 AM  14 years ago
Remyrw

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Bloomfield, CT - usa

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cyclic
try disconnecting your motors (note polarity, write it down, it's easy to forget) and then testing how the cyclic control is moving the swash. If it's moving incorrectly without the rotor's turning you have something connected incorrectly OR your radio's developed a problem.

Check collective too, and check both at once, to see if it's an issue that only comes up with the collective moved out of the starting point. After that, check that everything is connected properly, dig out the diagrams and photos... If you can post some close up shots of the head/swash area we might be able to diagnose if it's an incorrect linkage.
Remy
Practice in a sim, or it's practice fix practice fix...
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09-07-2006 06:22 AM  14 years ago
Skiddz

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Carlsbad, CA

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You may be seeing "gyroscopic precession", which is a search in itself. Basically, the rotor is a gyroscope, and the control inputs must act 90 degrees upstream in order to have the desired outcome.
Gyroscopic precession is taken care of in the design of the head, specifically the relationship between the feathering axis of the blade and the connection point on the ball link. This relationship is called Advance Angle.

I did a little write up about it a couple months back in this forum.

You can check out the thread HERE if you're interested.

What is probably happening is either the swash isn't dead nuts level when the right stick is centered, left is all the way down in normal mode -OR- one of the aileron servos is getting "lazy", possibly reversed or the servo arm isn't centered when the stick is centered. it could also be a link in a different hole than the other servos and the throws aren't the same.

Best bet is to do like Remyrw said. Disconnect the motor and exercise the swash. Full up on the left stick should pull the swash down evenly. It shouldn't tilt left, right or forward. If it does, check the channel reversing switches on the bottom of the Tx and make sure they're set per the manual or just flip one, move the stick and see if it make the problem better or worse. If worse, reset that channel and try another one.

Now try the right stick. If the left stick exercises were proper, the swash should tilt in the direction the stick is moved.

If the swash isn't level, pull the sheer pin and top screw and disconnect the links from the head to the swash and you can pull the entire head right off in about 60 seconds.

With the right stick centered, the left all the way down in NORMAL mode, all 3 servo arms should be perpendicular to the servo's body and the swash should be perfectly level. The top of the main shaft should protrude exactly 1/2" above the swash when it's all leveled up.

Tweak the links between swash and servos to get the swash absolutely perpendicular to the main shaft, then put the head back on. Make sure all the head links are the same length (measure 'em, don't eyeball 'em) and then make sure that both blades have the same amount of pitch when the sticks are neutral.

Getting the head set up on one of these things is pretty simple, but a bit tedious. Taek your time and measure everything. The closer you can get to perfect, the better it'll fly.

Good luck!
A helicopter is 10,000 parts spinning rapidly around an oil leak.
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09-07-2006 07:42 PM  14 years ago
CK_

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Redondo Beach, CA

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If you're talking about giving it forward cyclic while still on the ground then what you describe is perfectly normal. The disk will tilt to one side. Once the skids are off the ground this effect goes away.
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