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How to hover



 
 
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  #1  
Old December 29th 06, 07:50 PM posted to rec.aviation.rotorcraft
Wannafly
external usenet poster
 
Posts: 2
Default How to hover

Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.

I have read several articles and books about helicopter flying and I am
still a little confused as to what you have to do, from what I gather
there is constant control inputs to fly a helicopter and that a
helicopter is hover with its left skid low but at the same time I have
hearing tokeep the helicopter in a level attitude, so how can that be.

From what I gather so far, when you hover, you add left pedal, increase

collective and power, then right cyclic; what I am wondering is what
cues do you look for to determine what control inputs is needed and
where are your eyes focused for all of this. I read an article in
Avweb where the pilot was going to a higher helicopter rating and he
asked a more experience pilot about the trouble he was having and the
pilot told him to look up and after consideration from the less
experience pilot that worked for him, so look up at what-- the rotor,
something at eye level or not to look at the ground.

What I am trying to determine here is how to hover a helicopter, what
control inputs do you have to make and in what order, I have heard that
once one control input is made you have to use all of the controls but
dont you have to do it in a certain order and where and what are your
eyes focused and what are the cues that you are looking for to
determine which control input is needed. I am trying to determine the
mechanics and the cues needed to hover.

Thanks in advance for your response.

Ads
  #2  
Old December 30th 06, 12:34 AM posted to rec.aviation.rotorcraft
601XL Builder
external usenet poster
 
Posts: 97
Default How to hover

Wannafly wrote:
Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.

I have read several articles and books about helicopter flying and I am
still a little confused as to what you have to do, from what I gather
there is constant control inputs to fly a helicopter and that a
helicopter is hover with its left skid low but at the same time I have
hearing tokeep the helicopter in a level attitude, so how can that be.

From what I gather so far, when you hover, you add left pedal, increase

collective and power, then right cyclic; what I am wondering is what
cues do you look for to determine what control inputs is needed and
where are your eyes focused for all of this. I read an article in
Avweb where the pilot was going to a higher helicopter rating and he
asked a more experience pilot about the trouble he was having and the
pilot told him to look up and after consideration from the less
experience pilot that worked for him, so look up at what-- the rotor,
something at eye level or not to look at the ground.

What I am trying to determine here is how to hover a helicopter, what
control inputs do you have to make and in what order, I have heard that
once one control input is made you have to use all of the controls but
dont you have to do it in a certain order and where and what are your
eyes focused and what are the cues that you are looking for to
determine which control input is needed. I am trying to determine the
mechanics and the cues needed to hover.

Thanks in advance for your response.


If anybody thinks they can explain in writing how to properly hover is
full of crap.

Remember the old video of the guy spinning plates on the the ends of
multiple poles. That's what it is like to hover.
  #3  
Old December 30th 06, 01:04 AM posted to rec.aviation.rotorcraft
B4RT
external usenet poster
 
Posts: 28
Default How to hover


"Wannafly" wrote in message
oups.com...
Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.


There's no other good answer to your question except: "The correct ones."

I'm not being sarcastic, its just that your question is like asking "how to
I ride a bicycle."

The way you teach someone to hover is to give them each control one at a
time while you describe what they're doing incorrectly (which is usually
overcontrolling) and what they're doing correctly (usually very little at
the start). The student just eventually figures it out during which time the
instructor prevents expensive crashes.

From experience I can tell you that IGE hovering does not become totally
second nature for quite some time, my guess is a few hundred hours.

Bart


BTW: Happy New Years all you RAR fans, trolls, contributors, and lurkers!


  #4  
Old December 30th 06, 05:30 AM posted to rec.aviation.rotorcraft
Steve L.[_1_]
external usenet poster
 
Posts: 4
Default How to hover

Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.


There's no other good answer to your question except: "The correct ones."

I'm not being sarcastic, its just that your question is like asking "how to
I ride a bicycle."


I like this comparison. You can do both things only if you do not need
to think about it.

Maybe the original poster is confused about the theoretical basics. If
you have ideal (theoretical) conditions you don't need to do anything.
But this cannot happen in real life.
If the slightest disturbance occurs (and if there are no external - like
wind gusts - at all, the heli produces its own - always) the helicopter
will move into one direction.
Normal, simple helicopters then return to their initial position, and
overshoot this position by more than the initial disturbance. This
dynamic instability is inherent to helicopters with the main rotor
center of thrust above the center of gravity and the rotor disc trying
to keep its angle to the mast.

  #5  
Old December 30th 06, 01:27 PM posted to rec.aviation.rotorcraft
RPE
external usenet poster
 
Posts: 9
Default How to hover


Think of it this way, the control imput you just made changed all the
previous ones. So now that you did that you must readjust them all
again. Then you have to do it over and over again untill its back on the
skids in flat pitch.




"Wannafly" wrote in message
oups.com...
Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.

I have read several articles and books about helicopter flying and I
am
still a little confused as to what you have to do, from what I gather
there is constant control inputs to fly a helicopter and that a
helicopter is hover with its left skid low but at the same time I have
hearing tokeep the helicopter in a level attitude, so how can that be.

From what I gather so far, when you hover, you add left pedal,
increase

collective and power, then right cyclic; what I am wondering is what
cues do you look for to determine what control inputs is needed and
where are your eyes focused for all of this. I read an article in
Avweb where the pilot was going to a higher helicopter rating and he
asked a more experience pilot about the trouble he was having and the
pilot told him to look up and after consideration from the less
experience pilot that worked for him, so look up at what-- the rotor,
something at eye level or not to look at the ground.

What I am trying to determine here is how to hover a helicopter, what
control inputs do you have to make and in what order, I have heard
that
once one control input is made you have to use all of the controls but
dont you have to do it in a certain order and where and what are your
eyes focused and what are the cues that you are looking for to
determine which control input is needed. I am trying to determine the
mechanics and the cues needed to hover.

Thanks in advance for your response.



  #6  
Old December 30th 06, 02:02 PM posted to rec.aviation.rotorcraft
RPE
external usenet poster
 
Posts: 9
Default How to hover

Here is an excerpt from a previous posting here, author unknown but
knowledgeable. While he/she doesn't specificly address the "hover" alone
an explanation can be derived from it;

? O.K. Here we go!



As soon as we get off the ground we notice a tendency for the
helicopter to drift to the right due to the tail-rotor's thrust, so a
little left cyclic *pressure* is necessary to stay over one spot. I say
pressure because that's all it takes. Much more than that and the
helicopter will go too far to the left and slip off the "cushion" of
high-pressure air it is producing under the rotor and will settle to the
ground if power is not added. Not only that, but a series of
pilot-induced oscillations on all axes may develop. Let's say that we
move the cyclic to the left to correct for tail-rotor drift, and have to
suddenly move it back to the right to correct for the over-correction.
Now we find ourselves swinging back and forth to an increasing and
alarming extent. This is due to the helicopter's mass acting as a
pendulum under the spinning rotor, which tends to stay put much like a
spinning top. This is appropriately called "pendular effect". Not to
over-complicate things, but pendular effect is not the worst thing to
deal with when in a hover. Let's say that we experience tail-rotor drift
and correct for it using left cyclic pressure. Although the rotor is
still producing the same amount of thrust, we have just converted some
of that lifting thrust (called "lift component") to lateral thrust
("thrust component") by tilting the rotor disc slightly. To avoid
settling to the ground, we must add some lift component by adding
collective and simultaneously adding enough throttle to maintain rotor
RPM. While doing that we notice that the nose of the helicopter wants
to go to the right due to the increase in torque, so we add some left
pedal pressure, which stops the nose from moving, but since the tail
rotor needed more power to do that, and it doesn't have its own engine,
we had to steal some power from the main rotor. (Ya faller me?) Now
that the rotor has less power, the helicopter wants to settle to the
ground again, so we need to add more collective and more throttle and
more pedal... now you're too high! Uh oh! Less collective! Less
power! Right pedal! Now you're drifting to the left due to less thrust
from the tail rotor! Watch that rotor RPM! Better get outa this hover
and away

from the ground where its safe!



Now here's the fun part. Gently feed forward cyclic pressure and
simultaneous collective/throttle (and don't forget left pedal) until we
begin to gain forward speed. Now we just lost two good things:

Ground effect, which is that cushion I mentioned, and lift component
since we tilted the rotor forward. Just add some collective/throttle to
keep from digging a hole, and the appropriate amount of pedal to

hold heading. We quickly gain forward speed until we gain a good thing
to replace the two good things we just lost: translational lift.
Translational lift is what people are referring to when they say that a
helicopter's rotor system acts like a wing in forward flight. Kinda
sorta, but not exactly. It *flies* much the same but not because of
wing-like properties. It is simply because the helicopter now has a
constant supply of "still" air to climb upon, rather than sitting in its
own accelerated column of air. We can either

choose to nose over a bit more or reduce power and stay near the ground
to accelerate some more, or let the helicopter climb with its newfound
extra rotor efficiency--its your choice. (O.K., we skimmed the ground
'cause its fun.) Now we need to get over those trees...c'mon, that's
enough! Now, ease back on the cyclic enough to maintain good climb
speed and up we go like that Ferris wheel you used to hate so much.



The easiest part of all needs little explanation. Just do all the
same stuff you do in an airplane plus watch your rotor RPM. When you
want to turn, give it a little pedal to coordinate. Hold speed by
holding *attitude* with the cyclic, hold altitude with the collective.
Easy, huh? There's a little more to it, but you might not notice it
while in flight. Some things change with speed, and some mostly
sub-conscious corrections need to be made, but there are limits to
sub-conscious flight techniques. The following

paragraph is optional reading for those who only want a very basic
explanation of helicopter flight. (this involves math) :-)



Due to the rotor spinning rapidly, and the helicopter as a whole
moving forward, we have to deal with "dissymmetry of lift". Dissymmetry
of lift comes from one side of the rotating rotor disc moving into the
direction of travel of the helicopter, and the other side moving away
from it. The net effect is to add the speed of the helicopter to the
rotor's rotational speed on the dvancing side, and conversely to
subtract the forward speed of the helicopter from the retreating side of
the rotor. If the rotor has a rotational speed of 400 MPH at the tips,
and the helicopter is traveling at 100 MPH through the air, the net
speed of the advancing side of the rotor is 500 MPH. Under the same
conditions, the net speed of the retreating side is 300 MPH. If an
airplane tried to run its right wing through the air at 500 MPH and run
its left wing

through the air at 300 MPH, it would be doing snap-rolls until it
crashed. Dissymmetry of lift is the primary obstacle the helicopter
faces in significantly improving on current top speed records. Above the
approved top speed of a helicopter, the rotor blades are alternately
experiencing the extremes of Mach buffet, and of reverse flow...450
times a minute. The resulting rapid oscillation of center of pressure
on each blade can lead to catastrophic rotor system failure. The
vibration is a warning. The control effect as speed increases is that
the helicopter rolls towards the retreating side, and is corrected by
adjusting cyclic pressure against the roll. This is done without much
thinking except to re-trim the cyclic when speed changes significantly.
Another change that isn't really noticed is that the tail-rotor doesn't
need to work as hard at higher speeds due to the weather vane effect of
the tail boom. Airfoils are often placed on the boom to unload the
tail-rotor

at high speed/high power settings and free up power for lift/thrust.



This is boring as hell, so now we're going to land
somewhere...anywhere. See any place you want to stop and have a picnic?
How 'bout that little pond with the ducks and the waterfall tucked into
that gorge? Let's land on that sand bar. This is one place where those
fixed-wingers won't bother us.



Losing speed and altitude is basically the reverse process of
gaining them. To hold altitude and lose speed you ease back on the
cyclic to flare and reduce speed while lowering collective/throttle just
enough to hold altitude and maintain rotor RPM. To lose altitude
without losing speed, lower

collective/throttle until the desired rate of decent is reached. A
combination of both is usually used for approach to landing. At the
point of loss of translational lift, the rotor system will vibrate a
bit, but you're used to it by now (you'll be a bit numb by the end of
the flight). Besides, you'll be somewhat distracted by the sinking
feeling, followed by the confusion of having the nose suddenly jerk to
the right when you yank up on the collective

to stop sinking. (forgot that left pedal again, eh?) Anyway, when
you've established a hover (hopefully in ground effect and over a clean,
level spot) you can decrease collective until touching the ground. That
was an over-simplification, but you get the idea. Now we can eat.
Don't freak out too badly when you notice those wires--damn close, but
you're alive!




"Wannafly" wrote in message
oups.com...
Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.



  #7  
Old December 30th 06, 04:59 PM posted to rec.aviation.rotorcraft
Stuart & Kathryn Fields
external usenet poster
 
Posts: 328
Default How to hover

It is relatively easy to hover. Set and maintain the rotor rpm that is
required, slowly raise the collective to achieve a hover altitude of 3ft.
and do whatever you need to do to keep the helicopter doing what you want it
to do. Oh BTW, don't over control.
WARNING: The hovering helicopter is strongly attracted to all surrounding
neighboring zip codes.
Remember also the absolute necessary item for helicopter flight is noise..
When the noise quits, flight will shortly also quit..

--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell

www.vkss.com
www.experimentalhelo.com


"Wannafly" wrote in message
oups.com...
Hello, what are the control inputs required in a hover in an ideal
situation, what I am trying to figure out is what are you doing in a
no-wind situation to hover.

I have read several articles and books about helicopter flying and I am
still a little confused as to what you have to do, from what I gather
there is constant control inputs to fly a helicopter and that a
helicopter is hover with its left skid low but at the same time I have
hearing tokeep the helicopter in a level attitude, so how can that be.

From what I gather so far, when you hover, you add left pedal, increase

collective and power, then right cyclic; what I am wondering is what
cues do you look for to determine what control inputs is needed and
where are your eyes focused for all of this. I read an article in
Avweb where the pilot was going to a higher helicopter rating and he
asked a more experience pilot about the trouble he was having and the
pilot told him to look up and after consideration from the less
experience pilot that worked for him, so look up at what-- the rotor,
something at eye level or not to look at the ground.

What I am trying to determine here is how to hover a helicopter, what
control inputs do you have to make and in what order, I have heard that
once one control input is made you have to use all of the controls but
dont you have to do it in a certain order and where and what are your
eyes focused and what are the cues that you are looking for to
determine which control input is needed. I am trying to determine the
mechanics and the cues needed to hover.

Thanks in advance for your response.



  #8  
Old December 31st 06, 10:40 AM posted to rec.aviation.rotorcraft
Toby
external usenet poster
 
Posts: 1
Default How to hover

Great little starter for you

http://www.hurtwood.demon.co.uk/Fun/copter.swf


 




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