Low G
Guest
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Low G
I once read an article in "Helicopter World" about the safety course at the Robinson factory. The writer stated that you can't get into LOW G below 60kts, but there was no aerodynamic reason behind this bald statement so I was wondering if anybody out there knows the answer?
Also: When experiencing LTE (loss of tail rotor effectiveness) - somebody is trying to convince me the corrective action is left cyclic (assuming counterclockwise rotation) and not down collective and fwd cyclic.
I experienced this twice and it happened so fast that down collective and cyclic stick forward was the only thing that entered my mind at the time.
Thanks
Also: When experiencing LTE (loss of tail rotor effectiveness) - somebody is trying to convince me the corrective action is left cyclic (assuming counterclockwise rotation) and not down collective and fwd cyclic.
I experienced this twice and it happened so fast that down collective and cyclic stick forward was the only thing that entered my mind at the time.
Thanks
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Eagles :
My understanding from the sheer physics point of view is that the speed is irrelevant.
If you bunt ( push over ) at any speed you're risking low G. Other possibilities I'm aware of are at the top of a cyclic climb, again if you push over in an ill-advised plan to attempt to continue flying, rather than planning the finish of the climb well ahead to keep G positive.
[This message has been edited by WhoNeedsRunways (edited 03 November 2000).]
My understanding from the sheer physics point of view is that the speed is irrelevant.
If you bunt ( push over ) at any speed you're risking low G. Other possibilities I'm aware of are at the top of a cyclic climb, again if you push over in an ill-advised plan to attempt to continue flying, rather than planning the finish of the climb well ahead to keep G positive.
[This message has been edited by WhoNeedsRunways (edited 03 November 2000).]
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Eagles66,
Hello there. Maybe I can help. LTE is caused when the T/R is stalled. If you pay close attention the a/c will actually talk to you. When you just about reach the limit of peddle it is probably time to regroup. Anyway the preffered method is to obiously not get there in the 1st place(consult perf charts). If that did not work THEN Altitude permiting lower collective, cyclic in the direction of rotation(slightly) and lower nose to gain speed. Peddle against rotation(left unless you fly Russian or French helos) The right cyclic will help unload the T/R also. but above all LISTEN TO THE HELICOPTER, it talks.
hope this helps,
j
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What can you conceive more silly and extravagant than to suppose a man racking his brains, and studying night and day how to fly?
— William Law, 'A Serious Call to a Devout and Holly Life XI,' 1728
[This message has been edited by before landing check list (edited 05 November 2000).]
Hello there. Maybe I can help. LTE is caused when the T/R is stalled. If you pay close attention the a/c will actually talk to you. When you just about reach the limit of peddle it is probably time to regroup. Anyway the preffered method is to obiously not get there in the 1st place(consult perf charts). If that did not work THEN Altitude permiting lower collective, cyclic in the direction of rotation(slightly) and lower nose to gain speed. Peddle against rotation(left unless you fly Russian or French helos) The right cyclic will help unload the T/R also. but above all LISTEN TO THE HELICOPTER, it talks.
hope this helps,
j
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What can you conceive more silly and extravagant than to suppose a man racking his brains, and studying night and day how to fly?
— William Law, 'A Serious Call to a Devout and Holly Life XI,' 1728
[This message has been edited by before landing check list (edited 05 November 2000).]
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I'm not sure about the '60 knot' reference, but it does make sense that the aircraft must
have speed to encounter a low G mast bumping scenario. At cruising speeds, when the cyclic is pushed forward abruptly, the nose pitches down but the aircraft's momentum allows it to continue on its previous trajectory. This reorients the oncoming flow
of air more perpendicular to the rotor disk, reducing individual rotor blade angles of attack, and ultimately (if the pushover was aggressive enough) a loss of rotor thrust. Now at low speeds or in a hover, there is not enough momentum involved, and the helicopter simply begins a decent as the cyclic is pushed forward (the disk remains
sufficiently loaded). That's the way I see it anyhow. As for the comment about LTE above which stated 'the tail rotor is stalled...', I have to disagree with that as well. Pick up the AC on LTE and study the 3 critical wind azimuths which produce LTE. In no instance has the tail rotor stalled, but rather, the demand for tail rotor thrust has exceeded that which is currently available.
have speed to encounter a low G mast bumping scenario. At cruising speeds, when the cyclic is pushed forward abruptly, the nose pitches down but the aircraft's momentum allows it to continue on its previous trajectory. This reorients the oncoming flow
of air more perpendicular to the rotor disk, reducing individual rotor blade angles of attack, and ultimately (if the pushover was aggressive enough) a loss of rotor thrust. Now at low speeds or in a hover, there is not enough momentum involved, and the helicopter simply begins a decent as the cyclic is pushed forward (the disk remains
sufficiently loaded). That's the way I see it anyhow. As for the comment about LTE above which stated 'the tail rotor is stalled...', I have to disagree with that as well. Pick up the AC on LTE and study the 3 critical wind azimuths which produce LTE. In no instance has the tail rotor stalled, but rather, the demand for tail rotor thrust has exceeded that which is currently available.
Guest
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lmlanphere, actually the tail rotor goes through the same thing as the main rotor when it settles with power. Just on a different plane.
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How could they possibly be Japanese planes?
— Admiral Husband E. Kimmel
Believe me, Germany is unable to wage war.
— Former British Prime Minister David LLoyd George, 1 August, 1934.
