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Rotor Blades R/C Helicopter Rotor Blade Discussions


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Old 06-12-2018, 12:34 PM   #1 (permalink)
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Default Rotortech Blades

Just got a set of RT690 blades and got to fly them over the weekend. After the flight when I land a the heli spools down, it shakes violently. I tried tightening blade grips and loosening them too, still does it. They fly fine in the air just shake on spool down.

Wondering if anybody else has had a issue or is it just my set?

Thanks, Jeff
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Old 06-12-2018, 08:53 PM   #2 (permalink)
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What heli?
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Old 06-13-2018, 10:16 AM   #3 (permalink)
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I did not say, because I do not think that it matters. The heli does not exhibit this behavior with other blades, just this set of Rotor Techs.
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Old 06-13-2018, 11:41 AM   #4 (permalink)
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Things to check. Static balance, dynamic balance, unequal grip tightness, and defects in the surface of the blade grip where it contacts the blade. If you use spacers, use a brand new set that has no surface blemishing, as that can grab a blade, or the grip, in the spooling up and down of a blade. You didn't mention the surface you were taking off from as that can have an impact if some of the above mentioned items are not within balance or equal tension. Hope this helps.

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Old 06-14-2018, 12:57 PM   #5 (permalink)
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I suggest that you put your previous blades back on and see if the dance goes away.
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Old 06-14-2018, 10:07 PM   #6 (permalink)
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Quote:
Originally Posted by kineticheli View Post
Just got a set of RT690 blades and got to fly them over the weekend. After the flight when I land a the heli spools down, it shakes violently. I tried tightening blade grips and loosening them too, still does it. They fly fine in the air just shake on spool down.

Wondering if anybody else has had a issue or is it just my set?

Thanks, Jeff
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Originally Posted by kineticheli View Post
I did not say, because I do not think that it matters. The heli does not exhibit this behavior with other blades, just this set of Rotor Techs.
It's about the whole heli not just the blades. Have you measured the blades' weight and test balanced them as well as check and compare CG of each?

I've had this experience before and it was due to resonance on the heli not the blades.
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Old 06-18-2018, 10:57 AM   #7 (permalink)
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Thanks for all the suggestions and help, but I wasn't looking to fix the problem. I was asking if any others have had issues with the Rotor Tech blades. Again, the heli flies great in the air, the shake is only on spool down. I did reduce by loosening the blades grips, but it is still there. I finlly just put a different set of blades on the heli and no issues at all.
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Old 06-23-2018, 03:34 PM   #8 (permalink)
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Some blades have an aggressive chord-wise CG where others don't. Blades with a chord-wise CG more towards the trailing edge will "cant" somewhat ahead of the blade hinge bolt. These blades can cause exaggerated ground resonance on spool down if you throw in too much negative pitch.
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Old 06-26-2018, 08:27 PM   #9 (permalink)
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I have flown many and various RT blades over the years and only had that issue once on a Century Swift heli. Tried some other blades and found it did the same. It proved to be an airframe / ground resonance that was cured by spreading the landing gear struts out another 2 cm.
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Old 10-28-2018, 03:43 PM   #10 (permalink)
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I have flown many different sets of Rotor Tech blades over the years and have never had any issues with the blades. I have used from 280mm to 760mm sizes. Never say never but most likely something else. As for an chord wise CG on the RT blades , I had a swash ball come out on the pitch link to the grip on a Logo many years back. The heli dropped some and took more pitch to fly but I brought it around and landed it to find out I was flying on one blade and the other just feathered out . Rotor tech is my go to blade , I have tried many other brands over the years but feel the Rotor Tech blades are the best all around blade for me.
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Old 12-16-2018, 03:26 AM   #11 (permalink)
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Quote:
Originally Posted by Dennis P View Post
I have flown many different sets of Rotor Tech blades over the years and have never had any issues with the blades. I have used from 280mm to 760mm sizes. Never say never but most likely something else. As for an chord wise CG on the RT blades , I had a swash ball come out on the pitch link to the grip on a Logo many years back. The heli dropped some and took more pitch to fly but I brought it around and landed it to find out I was flying on one blade and the other just feathered out . Rotor tech is my go to blade , I have tried many other brands over the years but feel the Rotor Tech blades are the best all around blade for me.
I didn't think that flying with a pitch link missing was possible.
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Old 12-16-2018, 07:44 AM   #12 (permalink)
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I didn't think that flying with a pitch link missing was possible.
Until you think the loss in lift is due to being inverted and give hard negative collective. Then the rest and heli is history! Guess how I know?
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