"stirring the pot"
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"stirring the pot"
I've looked through Wagtendonk and searched this thread but can't find an answer to this question.
Aerodynamically, why does a helicopter settle when constant unneeded corrections are made with the cyclic in a hover? Or why does efficiency decrease with the same movements in forward flight.
The effect must act to reduce TRT but how? Is it simply because you're increasing lean-back angles for a fraction of time?
Any help would be much appreciated...
Thanks
Aerodynamically, why does a helicopter settle when constant unneeded corrections are made with the cyclic in a hover? Or why does efficiency decrease with the same movements in forward flight.
The effect must act to reduce TRT but how? Is it simply because you're increasing lean-back angles for a fraction of time?
Any help would be much appreciated...
Thanks
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Mate,
Your sort of on the right track there.
Basically, if you're in a steady hover and push and pull on the cyclic with out making adjustments to the collective, you will descend as you have stated.
The reason for this is because if you've got the cylic in the optimum position for a steady hover, the TRT and the vertical component of lift are at a maximum for that particular power setting. If you then change the cyclic position (and therefore tilt the lift vector to one side), the vertical component of lift (keeping you in said position) will be reduced. This will of course result in a descent.
Have a look at the vector diagram that relates to a steady hover situation again. Tilt the total lift vector over even more and the vertical component of lift will reduce.
Hope this helps,
P68
Your sort of on the right track there.
Basically, if you're in a steady hover and push and pull on the cyclic with out making adjustments to the collective, you will descend as you have stated.
The reason for this is because if you've got the cylic in the optimum position for a steady hover, the TRT and the vertical component of lift are at a maximum for that particular power setting. If you then change the cyclic position (and therefore tilt the lift vector to one side), the vertical component of lift (keeping you in said position) will be reduced. This will of course result in a descent.
Have a look at the vector diagram that relates to a steady hover situation again. Tilt the total lift vector over even more and the vertical component of lift will reduce.
Hope this helps,
P68
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I have heard it (putting in small cyclic inputs) called 'spilling the lift,' which would seem to be a functional description of what's going on. It was explained to me as one way to achieve a smooth touchdown.
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I have never seen a really experienced and good pilot that stirs the cyclic.
I really truly, absolutely, detest, pilots that do, and then even more when they actually feel they are really sensitive and have superior control of their machine!!
Unfortunateley the R22 tends to make "pot stirrers", I guess its because the controls are a little slopy?
I really truly, absolutely, detest, pilots that do, and then even more when they actually feel they are really sensitive and have superior control of their machine!!
Unfortunateley the R22 tends to make "pot stirrers", I guess its because the controls are a little slopy?
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Leave it ALONE!
It would be like driving along a straight road road at a constant speed whilst moving the wheel back and forth for no reason.
I makes me crazy when I see pilots stirring away too
I makes me crazy when I see pilots stirring away too
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I sat in on a great demo once in a Schweizer of how to get the ship down from the cruise with a stuck collective. Basically, put it into a tight spiral over your chosen spot until you're as low as you dare, then level her out and stir the cyclic like crazy until she settles. I nearly died laughing, but it works.
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Originally Posted by puntosaurus
I sat in on a great demo once in a Schweizer of how to get the ship down from the cruise with a stuck collective. Basically, put it into a tight spiral over your chosen spot until you're as low as you dare, then level her out and stir the cyclic like crazy until she settles. I nearly died laughing, but it works.
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I have heard it (putting in small cyclic inputs) called 'spilling the lift,' which would seem to be a functional description of what's going on. It was explained to me as one way to achieve a smooth touchdown.
..and not a bad way to completely cock up an otherwise ordinary landing!
If you want to achieve a smooth touchdown learn how to fly the machine properly and use your collective. There is a special corner of the VERY HOT place reserved for people who flap their cyclics about. Where do these ideas come from?!
..and not a bad way to completely cock up an otherwise ordinary landing!
If you want to achieve a smooth touchdown learn how to fly the machine properly and use your collective. There is a special corner of the VERY HOT place reserved for people who flap their cyclics about. Where do these ideas come from?!
Everyone over corrects at the beginning. After that there are those who learn how to fly smooth and those who learn how to correct their over correcting (If you can understand that) and fly under the false belief that they are smooth operators. 1000's and 1000's of hours doesn't seem to make them click. I personally think that it is retarded relationship with the rotor disk. It's really not that hard to realise and achieve yet it would have to be 6 or maybe 7 in 10 that do it.
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Well, excuuse me!
I am a humble plank driver with less than an hour spent on the odd hop in a helicopter. I got this explanation about 'spilling the lift' without really forming any opinion about it, other than that it sounded plausible. Whether it is good technique or akin to drying your cat off in the microwave is far beyond my ken.
All I know from direct observation of the Nigeria Police Air Wing in action, trying to land a Long Ranger on their ramp, is that some guys seem to get very wobbly indeed just trying to hit Planet Earth. The helo was bobbing up and down like a fishing float with a carp on the hook, there. And on the other hand the Pan African pilots at Escravos used to make it look so easy I thought, 'I could do that!' So I guess from what I have just been told this is the sort of 'crutch' that a pilot might use if he's not so handy with the collective. Live and learn.
In the wonderful fixed-wing world we have an equivalent, the guy who gets to stirring the ailerons and elevators trying to achieve a really smooth touchdown. There you are, floating along in ground effect with what looks like a Bruce Lee action sequence going on over there; the controls have so little 'bite' that the airplane really isn't reacting very much but yer man is so busy that he hasn't noticed that! Of course if you point this out to him he gets mortally offended that you are criticising some technique he was taught by some goofy instructor way back when. Sigh...
All I know from direct observation of the Nigeria Police Air Wing in action, trying to land a Long Ranger on their ramp, is that some guys seem to get very wobbly indeed just trying to hit Planet Earth. The helo was bobbing up and down like a fishing float with a carp on the hook, there. And on the other hand the Pan African pilots at Escravos used to make it look so easy I thought, 'I could do that!' So I guess from what I have just been told this is the sort of 'crutch' that a pilot might use if he's not so handy with the collective. Live and learn.
In the wonderful fixed-wing world we have an equivalent, the guy who gets to stirring the ailerons and elevators trying to achieve a really smooth touchdown. There you are, floating along in ground effect with what looks like a Bruce Lee action sequence going on over there; the controls have so little 'bite' that the airplane really isn't reacting very much but yer man is so busy that he hasn't noticed that! Of course if you point this out to him he gets mortally offended that you are criticising some technique he was taught by some goofy instructor way back when. Sigh...
Last edited by chuks; 23rd Mar 2006 at 09:58.
