PPRuNe Forums - View Single Post - Certification of Robinson Helicopters (incl post by Frank Robinson)
Old 21st Nov 2000, 21:56
  #120 (permalink)  
HeloTeacher
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I have to reply to this, as much as it pains me to add to the cacophony:

Lu wrote:

Regarding stick input during zero G flight let us assume that the pilot has corrected for the 18 degree offset and the cyclic is placed forward and right of the rigged neutral position. As such, the helicopter is flying forward and not to the left. If the helicopter enters the zero G condition with the cyclic in this position the following can happen:

1) If he pulls straight back he will not add to the right roll set up by the tail rotor thrust.

2) If he pulls back and slightly to the left he will add to the right roll component.

3) If he pulls back and further to the left he will compensate for the 18 degree offset and not add to the right roll component

4) If he pulls back and even further to the left he will introduce a left roll component causing high flapping loads and possibly lose his rotor system or cause a rotor incursion.

With the intensity of pucker factor being so high during a zero G condition which direction would you move the cyclic if you were in that situation. Refer to my point 1 above and think about the sense of aircraft movement relative to cyclic stick displacement. Does this sound right? What if these same conditions existed in your automobile?

REGARDING YOUR LAST QUESTION ABOUT CHANGING THE RULES RELATIVE TO RMS Vs. ENGINEERING I WOULD STAND A BETTER CHANCE OF CHANGING THE BIBLE TO RECOGNIZE GOD AS BEING FEMALE.

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Lu, it doesn't matter what you do with the cyclic in a zero-G situation, the cyclic controls nothing but the disc. The right roll of the FUSELAGE is caused by tail-rotor effects, aft cyclic merely reloads the disc by changing the disc attitude relative to the prevailing airflow, once the disc is once-again loaded (even slightly) do what is required to maintain aircraft control.

Left cyclic applied in the mistaken belief that it will correct the right roll is what kills so many pilots, especially low-helo, high-aeroplane time pilots who have not yet learned adequate respect for low G in helicopters.

With reference to earlier comments I didn't copy, rig whatever pitch you want in the blades, it will not affect overpitching one iota, only exceedence of engine power will do that. Pull it in the hover, do a hover check (if you didn't you are't a helo pilot) and you will know whether it is grossly out of rig in collective pitch.

Now Lu, are you telling me that the 60 knot (.6 VNE) full application of pedal is/was a normal procedure? You are most certainly insinuating this when you state that there is "now" a restriction preventing this maneuver.

By the logic you have presented here all helicopters so certified should have a demonstrated crosswind capability at least equal to .6 VNE? I don't recall any.

The R22 was designed to the limits of what could be done in its weight and cost class. It was not designed as a trainer, it was used in this manner because it was economical. Everyone then assumed it was just a rotary C-150. It isn't.

I read earlier that people were stating that it had been taught that it is impossible to recover from an engine failure on climbout. I have had a student mistakenly roll the engine off on me in the climb. I got on the controls, lowered the pole, and recovered quite fine thank-you, despite being in the middle of talking with my hands.

I will be reviewing my old R22 manual tonight to see exactly what it says in section 4, not the snippets I see here.

Please send me this report, I would very much like to read it:
[email protected]

And I have NEVER seen a helicopter that smoothly transitioned to forward flight without lateral cyclic input, rotary wing aerodynamics aren't that simple.