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mCP X Blade Micro CPx Helicopters Information and Help |
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05-26-2012, 06:58 PM | #1 (permalink) |
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Join Date: Jan 2012
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Blade Dynamics
I've played around with my little MCPX for a few months and observed something interesting about my rotor blades.
Not only is it important that the blades be balanced dynamically, but the overall blade stiffness and/or flexibility can be just as important. You might be able to see this. Just before liftoff, with the sun shining on the rotor disk, you may see the rotor disk "crawl around" (a tip that is very slightly high, revolve slowly around the disk). This happens as the collective goes from negative to slightly positive. The tips get loaded and flex. If things aren't exactly symmetrical, one will flex a bit differently than the other. A bit of interaction (vibration) will cause the rotor disk to move unsymmetrically. If the light is just right and you are paying attention, you will see a bit if disk crawl. This dose not necessarily mean you have a problem. But if you then notice flutter or vibration in the air, you may have a blade, or two that has a weak spot, or is not symmetrically stiff along its length. This may be caused by a small crack in the trailing edge or some other damage. I tried to make a set of high performance blades out of two bullet blades that shed their weights. I sanded off the bullet to the profile of the blade body very carefully. Well,,, I saw some blade crawl before liftoff. In the air, at first things seemed to be OK. Then I saw a bit of low frequency flutter on a gradual decent. Then noticed that tail fin was "blurry". The collective response was a bit sudden and things were not as smooth as normal. I went back to a set of new high performance blades and everything calmed down considerably. I will pick up another set of bullet blades to dampen out some responsiveness and try my best to keep from shedding those little weights. The only modification I make is to lightly sand, with 600 grit, the leading edge flashing and put a satin finish along the top and bottom faces.
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MCPx V1, MCPx V2, Eflite Extra 260 and GP Extra 300SP (fixed wing) DX6 Garry |
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05-26-2012, 09:45 PM | #2 (permalink) |
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Join Date: Mar 2006
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Interesting about the blades. I just got mine Friday and flew about 6 flights today with 2 crashes if you call them that. Just trying things I'm too uptight to do on my other heli's. My "bullet" blades now cause a vibration under load, the tail fin buzzes. When at zero pitch on the ground or briefly in the air, there is no buzz. If I put the other blades on, no problem. I guess these blades can work, but lose their integrity without showing any real damage.
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05-27-2012, 01:53 AM | #3 (permalink) |
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Check to see if the weights are still in both bullets
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05-27-2012, 07:50 AM | #4 (permalink) |
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Join Date: Mar 2006
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Yep, the weights are still there.
Sent from my LG-P509 using Tapatalk 2
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Matt Pantera P5 50 RNFBL, Blade 130X, mcpx, Gaui X5 FES |
05-27-2012, 12:09 PM | #5 (permalink) |
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Thread Starter
Join Date: Jan 2012
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Also, check by twisting each blade and look for a hair-line crack. I fought wobbles and vibration for a few flights before noticing a trailing-edge "micro-crack" out towards the tip. New blades, and things smoothed out just fine.
I threw a bullet weight in a "bush-landing". The next flight was OK, but a bit twitchy. It was back to smooth after I put new stunt blades on. It is a good idea to check the blades, especially the bullet-blades before each flight. - Check that pesky gear too. I prefer the bullet blades over the stunt blade at this point in my learning curve.
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MCPx V1, MCPx V2, Eflite Extra 260 and GP Extra 300SP (fixed wing) DX6 Garry |
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