High Speed Flight

[Dave Jackson]

The three primary contenders for VTOL with high-speed flight are the V-22 (http://www.the-crawfords.com/V22/index.htm), the Piasecki compound helicopter (http://www.stratmag.com/issueMar-15/page03.htm) and the CarterCopter (http://www.cartercopters.com). A noteworthy feature is that they all use wings for fast forward flight. Nick has mentioned on occasion that "There is no such thing as a free lunch" and unfortunately, during hover and slow flight, these wings represent an unnecessary weight and a drag in the rotor downwash.

The Sikorsky ~ XH-59A ABC (http://www.russian.ee/~star/vertigo/sik_s-69-r.html) represented a very different approach. It consisted of a pair of counter-rotating rotors in conjunction with an Advancing Blade Concept. This arraignment allowed the rotors to provide the lift in both hover and fast forward flight, thereby eliminating the need for wings. Again there is no free lunch and the prototype helicopter suffered from high vibration and high drag.

In regard to vibration; there is currently quite a bit of research being conducted into Higher Harmonic Control and Individual Blade Control.
In regard to drag; Sikorsky had mentioned that much of the drag could be reduced on subsequent versions by fairing the rotors. The ABC is also not subjected to the combined rotor and wing drag of the other high speed contenders.

It appears that the time is right for a renewed interest in the Advancing Blade Concept.

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3top,

How's that for a sales pitch? :)

Dave J

[3top]

Hi Dave,

GREAT (b)pitch!!!!

I hope it works! ABC is just too fantastic a concept....

However individual bladecontrol, fly by wire, ...I am not too big a fan of that, except you find a way for an idividual blade control based on mechanical principals and not fly by wire or light. As long as electronic equipment (like GPS`s, etc) keep on quitting on me at the most inoportune times I have a hard time to trust that concept.
There got to be a reason why Sikorsky did not go with a fly by wire/light system on their new ship (Nick...?), although it ran side by side with the NH90.

It seems logical, as there are way less moving parts to fail, but when it fails there is nothing a human could do to control the thing....

Just look at the V-22 prototyp that crashed for wrong wiring on the maiden flight - AND it turned out that the other was wired wrong as well, just not that bad...

Dave, PLEEEASE keep your projects at least flyable if the gadgetry fails!!

:) :D :) 3top