oldfart
Elite Veteran
Location: Vancouver, Canada
| Ray
The flybar effects two functions - stabilization and cyclic acceleration.
The weight of the flybar is the biggest contributor to the stabilization equation. The longer or shorter the flybar also has some effect here (as it acts as the moment arm), but it does not have as much effect on the satbilization as it will on cyclic acceleration.
What is cyclic acceleration? It is the measure of how fast the heli will get up to its' maximum roll or pitch rate. Think of the maximum roll or pitch rate to be the maximum speed of your car. The acceleration rate will be the time it will tacke to accelerate to that max speed.
The flybar paddles are "wings" what "fly" the flybar (cause it to move the seesaw up and down). So they also will come into the equation, but for the rest of this discussion, we will assume the use of the same paddles.
The longer the flybar (as long as it is thick enough to stay rigid) the faster will it acclerate into and out of, a cyclic command. This is because the paddle "wing" is now traveling at a higher velocity. Think of the basic force equation - Force = Mass x velocity squared. (F = M x V x V). So the increase in speed will give the "wing" an increase in power as a square function, while the moment arm increase for stability will only increase as a linear function.
Of course, any winds in a hover will also have a bigger effect on the paddles (wings) which can become detrimental, if the flybar becomes too long. And so can the "headwind" in FFF or FBF have detrimental effects, if the flybar becomes too long (e.g. can cause pitch up or down depending on attitude - right side up or inverted, going forward or backward).
Also, a longer flybar can accelerate the vertical movement of the flybar fast enough, in some situations, to even cause the flybar itself to break when it hits the mechanical limit of its' seesaw movement..
That is it in a nutshell...if we are only considering the relative length of a flybar in a given system. |
