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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Spectra tail grips step 1
03-14-2010 07:29 PM  8 years agoPost 21
smallplanes

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Thanks Raja i just want to help,but i only have so much time in a day so i can't do everything. I have three kids and they do ever sport so i'm the baby sitter most of the time. I know i talk off the wall sometimes but i do know my job very well so i just try to help. Just like a lot of you have a problem with Irwin at QWW but he has been nothing but nice to me and i'm going to help him no matter what. But don't worry i will not lie for him or no one else so i will tell you just what i have learned. Thanks for all of us sticking together were like a family on here and it's great to help and be helped. I have noe enimes on here i like everyone so let all stick together for one goal and that is to get a gasser flying no matter the make or model.

Thanks to all of you that have helped me
Ivan


Spectra G 26cc
Jewel
Bat 27cc
Trex 700<br

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03-14-2010 10:24 PM  8 years agoPost 22
oldfart

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Vancouver, Canada

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olddude i'm not sure what your talking about can you put that in blue coller terms?
If a blade flutters - it will now have forces that will try to break the spindle - like when you apply laterally forces back and forth to flex a 1/16 OD solid wire until it breaks.

If the blade is properly designed, it will not have any flutter generating dynamic forces that apply undesireable lateral forces that try to flex the spindles. The only forces applied to the spindle, will be those that result from the pitch changes. These are not all that great as they are constant as they pull or push the tail in the direction commanded.

If the blade is such that chordwise center of gravity and/or center of lift are situated in front of, or behind, the pivot center of the spindle shaft, then there will always be a flutter generating force components that will be present.

And this will be even worst if the blade tips are flexible enough to start to vibrate or resonate at the same time.

If there are no unwanted flutter type of forces in the rotor, then all the spindle really has to contend with is the forces pulling outward. So now take the same wire and pull outwards on both ends. Kinda hard to break now, isn't it?

This is a bit difficult to describe without diagrams, but hopefully the flexing of the wire and the pulling on the wire example will help illustrate what I am trying to convey.

Phil

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03-15-2010 12:10 AM  8 years agoPost 23
smallplanes

rrElite Veteran

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I think i get what your saying even thought i still don't understand. If i make both grips the same weight want it work?

Thanks
Ivan


Spectra G 26cc
Jewel
Bat 27cc
Trex 700<br

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03-15-2010 12:40 AM  8 years agoPost 24
oldfart

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Vancouver, Canada

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What I am saying, is that the weight of the grips are not the issue. Heck, you can machine some heavy weights that are balanced (equal weights) all around and install them on the spindles and crank up the RPM - no problem.

The resultant centrifugal/centripetal forces which pull out/in on the spindle, will not be an issue unless your weights get ridiculously high.

What will be an issue, in any type of rotor system that does not have any damping to compensate, is the forces that will cause any protrusions (e.g. rotor blades, blade grip control arms etc.) from fluttering.

Have you ever seen the "woof and poof" issue develop in the main rotor of a heli like the Raptor, old Shuttle or a heli with extremely worn dampers? That is flutter at its' extreme.

A tail rotor is like a small main rotor. But it is oriented on its' side and does not have a flybar system or special damping systems that would look after any blade anomolies. And to compound everything, it is also turning at a rotor speed that is 4.5 to 5 times faster then the mainrotor. So in bigger tail rotors as we have in 30 nitro and larger helis, if they are used with badly designed tail blades (there are many out their), then the stiffer the grips the more prone the rotor will be to breaking of the spindles.

Poorly designed blades, or blade grips, can also cause mistracking, which will have the same effect as in a mainrotor - an unwanted vibration, but at a much higher frequency.

The biggest problem with diagnosing such phemomena in a tail rotor, is that due to its high rpm, these vibes and flutterings cause more of a visible blur that is harder to see and/or an audible buzz that may not be understood, until something fails.

Phil

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03-15-2010 11:33 PM  8 years agoPost 25
smallplanes

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Takes olddude i think i follow you but when i make a set they will be perfect to each other. I'm going to thin down the grips and add the weigh mod and will see how they tun out. i will test them on mine before i let someone else try them unless they want to take the risk with me but i can't promise the first batch with be perfect. If anyone has any tips or drawings they have in mind please show me.

Thanks guys
SP


Spectra G 26cc
Jewel
Bat 27cc
Trex 700<br

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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Spectra tail grips step 1
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