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Servo Flap Controlled Rotor why so rare?

rotor blades blade tail rotor aerodynamics eurocopter as350 ec135

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#1 chrispochari

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Posted 18 April 2017 - 21:38

What is the Servo Flap and How Does it Work? The servo flap is a small airfoil located at about 75 percent span of the rotor blade, situated on the trailing edge of each rotor blade. These flaps are controlled by the pilot through push-pull control rods and their function is similar to that of an elevator on fixed wing airplanes. Moving the trailing edge of the flap upward moves the leading edge of the main rotor blade up. This increases the rotor pitch or the lift in very much the same manner as the elevator, on a fixed wing aircraft, changes the angle of attack on the wing. Thus the helicopter pilot can cause the angle of attack of the flap to increase or decrease in pitch, causing the helicopter to alternately dive or climb. 

So with that said why isn't it used more?

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#2 Dnr032

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Posted 19 April 2017 - 18:58

Because it is a freak of nature!!!

#3 Eric Hunt

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Posted 20 April 2017 - 00:19

The $imple an$wer i$ the co$t of making the$e $ervo flap$.

 

Hiller had a type of servo, but not in the rotor.

 

Bell 214ST had a flap in one blade, but that was for tracking those massive slabs.



#4 pokey

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Posted 20 April 2017 - 02:52

Design
The simplicity of the K-MAX® design is inherently safer and more reliable.

A single engine, a single transmission, a servo-flap controlled, counter-rotating rotor with no high-pressured hydraulic system, and no tail rotor mean fewer essential systems and low maintenance costs.

 

Kaman's had this type working for years.



#5 pokey

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Posted 20 April 2017 - 09:28

The $imple an$wer i$ the co$t of making the$e $ervo flap$.

 

Hiller had a type of servo, but not in the rotor.

 

Bell 214ST had a flap in one blade, but that was for tracking those massive slabs.

 

Not so sure it was cost. Care to elaborate on why so expensive?

 

Didn't Hiller use "paddles" as a 'control rotor'?

 

Bell 214ST "flap" ?  you mean a trim tab? or what our OP is suggesting: an actually hinged and rotor controlling flap?



#6 Eric Hunt

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Posted 20 April 2017 - 16:17

 

 

Not so sure it was cost. Care to elaborate on why so expensive?

Talking about the 3 flaps on the "blue" blade in the video - a good idea but expensive

 

 

Didn't Hiller use "paddles" as a 'control rotor'?

 

That's what I said, but they were not IN the rotor, they were at 90 degrees to it

 

 

 

Bell 214ST "flap" ?  you mean a trim tab?

 

The topic is "flaps in the rotor" so the 214ST is an example of a flap in the rotor, but as I said, it is for tracking the blade, and yes, it is a trim tab to use the correct terminology.







Also tagged with one or more of these keywords: rotor blades, blade, tail rotor, aerodynamics, eurocopter, as350, ec135

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