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ProModeler Scorpion Power
jackp332

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Claremont, Nh USA

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Can main blades that are too tight in the grips cause a head shake or a vibration? Is there some sort of a spec or test people use to set this when they tighten the bolts?

06-16-2016 12:25 AM
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Dr.Ben

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Richmond, VA, USA

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Absolutely and especially at lower headspeeds.

Unless you're doing blade stop autos, set the tension enough so if the model is on its side, the blades will more or less hold their position. It's a bit subjective, but once you know what you're looking for, it's easy to replicate.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
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06-16-2016 12:41 AM
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Aaron29

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USA

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You should be able to hold the helicopter sideways, with the blades longitudinally, without the blades dropping due to gravity, as Dr. Ben said.

However, jolting the helicopter while sideways should result in some blade movement. Adjust the blade bolt such that this is the case. If jolting the heli while it's on its side doesn't result in any blade movement, that grip is too tight. If it falls on it's own due to gravity, it's too loose.

This was the method published in Curtis Youngblood's book. I've used it for a decade, never a boom strike.

However, as Dr. Ben also eluded to, the blade stop autorotation is the one time when you want them TIGHT. If they "bunny ear" during the stop it's likely all over for your heli.

I personally leave the blade stop stuff to the paid pros and set my blades the Curtis way.

06-16-2016 03:27 AM
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jackp332

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Claremont, Nh USA

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Great information. Thank you guys very much for that.

06-16-2016 09:10 AM
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artimus

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Buckley WA

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+1 Its The method i used for years...i call i the shake and break. Turn the heli on its side give it a shake and the blades should break and fall a few inches equally on both sides. Never had a boom strike with this method.

Fly Hard......Team Viagra

06-16-2016 09:41 PM
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meowguy

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Saco, ME

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Back in the day, "lead and lag" was a concept that we used to explain why the blades need to be able to have some movement. Now-a-days a more ridged rotor head is desired for smack down 3D. I prefer some movement and so I think the above advice is correct. If you are knowingly going to go out and shoot autos, I would opt for a very ridged blade to help prevent a boom strike. So 3D and Autos should be compatible with a stiff blade, where as scale and sport flying would be more supple.

"Sweet dreams and flying machines in pieces on the ground." J. Taylor

06-17-2016 10:00 PM
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jackp332

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Claremont, Nh USA

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I am definitely a scale and sport type flyer. I recently was having this shake issue in a large gasser and loosening up the blades as described fully cured it.

06-18-2016 03:31 AM
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Dr.Ben

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Richmond, VA, USA

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With low(er) head speed models, one of the ways you can tell if tension is too tight is to fly around, shoot an auto, and then come back into a hover. Blades often lead during autos, so when you lift back off into hover, the model will shake unless the tension is slack enough to let the blades lag back to their happy place.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

06-18-2016 03:47 AM
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jackp332

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Claremont, Nh USA

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Thank you for that explanation. I think I have always run my blades too tight in the past. I have seen this 'shudder' after an auto rotation that I could never explain on a few of my models.

06-18-2016 03:25 PM
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