Understanding Gyroplane Flight Controls.

XXavier

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I use upwind tilt in crosswind during the take off roll after the initial back tilt as I accelerate forward. I have to keep the nose straight with opposite rudder. That is also what I teach at Anahuac, as on most days, we have pretty strong cross winds.

Since I read Jean Claude's opinion in the thread he's mentioning above, I always take off with the stick back, crosswind or no crosswind, and it's far better... Tilting the stick to the wind results in losing revs fast and the takeoff run is longer. Besides, and for example, the wind may be coming 90º from the right at 30 km/h... but that's only when you are stopped... By the time you reach –for example, again– 80 km/h, in your run, the apparent wind is coming from a direction only 20º to the right...
 

thomasant

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Since I read Jean Claude's opinion in the thread he's mentioning above, I always take off with the stick back, crosswind or no crosswind, and it's far better... Tilting the stick to the wind results in losing revs fast and the takeoff run is longer. Besides, and for example, the wind may be coming 90º from the right at 30 km/h... but that's only when you are stopped... By the time you reach –for example, again– 80 km/h, in your run, the apparent wind is coming from a direction only 20º to the right...
Read my post again. What am I missing? I mention initial back stick for the take off roll. Did you read that??

Even the FAA manual advocates that. If you want, you can download a free copy of the manual.

Take off whichever way you want, as long as it is safe, and you don't drift or roll over.
 

thomasant

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the wind may be coming 90º from the right at 30 km/h... but that's only when you are stopped... By the time you reach –for example, again– 80 km/h, in your run, the apparent wind is coming from a direction only 20º to the right...
Can you explain that please.
 

XXavier

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Can you explain that please.
Captura de pantalla 2020-09-22 a las 14.30.56.png

Imagine you are stopped, before the runway, and that you have a wind of 30 km/h from one side, exactly 90º. Now, you start the run, and when you reach 30 km/h rolling ground speed, you have 'created' a component of 30 km/h from 360º. So, the wind has now an apparent direction coming from 45º... The higher the rolling speed, the closer the apparent wind direction to 360º... At 80 km/h is 20º 33'
 
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thomasant

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View attachment 1148375

Imagine you are stopped, before the runway, and that you have a wind of 30 km/h from one side, exactly 90º. Now, you start the run, and when you reach 30 km/h rolling ground speed, you have 'created' a component of 30 km/h from 360º. So, the wind has now an apparent direction coming from 45º... The higher the rolling speed, the closer the apparent wind direction to 360º... At 80 km/h is 20º 33'
We just use a Wind Component Chart to determine the headwind and crosswind that will affect our takeoff and landing.

Wind Component Chart.jpg

It's a lot simpler than doing heavy duty calculations. Do whatever works for you.
 

Jean Claude

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I use upwind tilt in crosswind during the take off roll after the initial back tilt as I accelerate forward.
Straight stick, full back, is good. The Adding a tilting to the side of the crossing wind decreases rpm acceleration,
and not decreases the torque of roll like that of a fixed wing in asymmetrical flight, because this effect does simply not exist on a rotary wing.
 
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thomasant

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Straight stick, full back, is good. The Adding a tilting to the side of the crossing wind decreases rpm acceleration,
and not decreases the torque of roll like that of a fixed wing in asymmetrical flight, because this effect does simply not exist on a rotary wing.
I'm not saying it is not good. That is how you start the take off roll, with stick back. Then tilt the disc to the wind as one accelerates.
Here's the FAA manual extract for cross wind takeoff:

Begin the maneuver by aligning the gyroplane into the
wind as much as possible. At airports with wide
runways, you might be able to angle your takeoff roll
down the runway to take advantage of as much headwind
as you can. As airspeed increases, gradually tilt
the rotor into the wind and use rudder pressure to
maintain runway heading. In most cases, you should
accelerate to a speed slightly faster than normal liftoff
speed. As you reach takeoff speed, the downwind wheel
lifts off the ground first, followed by the upwind wheel.
Once airborne, remove the cross-control inputs and
establish a crab, if runway heading is to be maintained.
Due to the maneuverability of the gyroplane, an immediate
turn into the wind after lift off can be safely executed,
if this does not cause a conflict with existing traffic.
 

XXavier

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We just use a Wind Component Chart to determine the headwind and crosswind that will affect our takeoff and landing.

View attachment 1148376

It's a lot simpler than doing heavy duty calculations. Do whatever works for you.


Graphic aids work, of course, but it's much better to understand what's really happening with the wind...
 

thomasant

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Graphic aids work, of course, but it's much better to understand what's really happening with the wind...
No doubt. All that I understand is that a headwind will shorten my takeoff and landing roll, and a crosswind will lengthen it. And it is easier for me to understand what is really happening with the Chart, as opposed to the detailed calculation you have posted. Frankly, I'm still trying to figure your calculation out, as my grasp of trig is hazy. I do not teach any of the students with those calculations, as most of them like it simple.
 

XXavier

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I'm not saying it is not good. That is how you start the take off roll, with stick back. Then tilt the disc to the wind as one accelerates.
Here's the FAA manual extract for cross wind takeoff:

Begin the maneuver by aligning the gyroplane into the
wind as much as possible. At airports with wide
runways, you might be able to angle your takeoff roll
down the runway to take advantage of as much headwind
as you can. As airspeed increases, gradually tilt
the rotor into the wind and use rudder pressure to
maintain runway heading. In most cases, you should
accelerate to a speed slightly faster than normal liftoff
speed. As you reach takeoff speed, the downwind wheel
lifts off the ground first, followed by the upwind wheel.
Once airborne, remove the cross-control inputs and
establish a crab, if runway heading is to be maintained.
Due to the maneuverability of the gyroplane, an immediate
turn into the wind after lift off can be safely executed,
if this does not cause a conflict with existing traffic.


Whatever the FAA manual may say, the fact is that as you increase your rolling ground speed, the apparent wind tends to align with the runway direction. So, with increasing rolling groundspeed, 'tilting the rotor into the wind' becomes more and more equivalent to 'tilting the rotor back'... And that's true for any direction and speed of the crosswind...
 

XXavier

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No doubt. All that I understand is that a headwind will shorten my takeoff and landing roll, and a crosswind will lengthen it. And it is easier for me to understand what is really happening with the Chart, as opposed to the detailed calculation you have posted. Frankly, I'm still trying to figure your calculation out, as my grasp of trig is hazy. I do not teach any of the students with those calculations, as most of them like it simple.


Of course, the chart works, but it's important to really understand what's happening... No need to make a calculation, indeed...

The crosswind will always prolong the run, yes, but –in the case of a gyro– you'll lose less revs if you tilt the rotor back, irrespective of the crosswind component...
 

thomasant

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Of course, the chart works, but it's important to really understand what's happening... No need to make a calculation, indeed...

The crosswind will always prolong the run, yes, but –in the case of a gyro– you'll lose less revs if you tilt the rotor back, irrespective of the crosswind component...
And the stick is tilted back for sure at the start of the take off. I have already stated that a couple of times.
 

thomasant

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Whatever the FAA manual may say, the fact is that as you increase your rolling ground speed, the apparent wind tends to align with the runway direction. So, with increasing rolling groundspeed, 'tilting the rotor into the wind' becomes more and more equivalent to 'tilting the rotor back'... And that's true for any direction and speed of the crosswind...
It is difficult to figure out change with the wind direction. I do not understand how that can change in the take off if it is blowing steady from a certain direction. That wind direction ought to be the same throughout the takeoff. I understand that the relative headwind and crosswind strength will change. That is also quite apparent from the chart that I posted.
 

XXavier

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And the stick is tilted back for sure at the start of the take off. I have already stated that a couple of times.

The more you increase your rolling (ground) speed, the more the direction of the resultant wind (the sum of all winds, natural or due to the motion of the observer) aligns with the runway direction. At the start, the gyro's rolling speed is zero, and the only wind is that of the 'natural wind'. But as the gyro accelerates along the runway, the wind change, both in speed as in direction. It's very important to understand this...
 

thomasant

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The more you increase your rolling (ground) speed, the more the direction of the resultant wind (the sum of all winds, natural or due to the motion of the observer) aligns with the runway direction. At the start, the gyro's rolling speed is zero, and the only wind is that of the 'natural wind'. But as the gyro accelerates along the runway, the wind change, both in speed as in direction. It's very important to understand this...
So what you are telling me is that during the start of the take off run, if there is a steady crosswind at 45 degrees to my right, that will become almost from 360 degrees direction by the time I'm airborne, (if I continue on the same path)??
 

XXavier

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It is difficult to figure out change with the wind direction. I do not understand how that can change in the take off if it is blowing steady from a certain direction. That wind direction ought to be the same throughout the takeoff. I understand that the relative headwind and crosswind strength will change. That is also quite apparent from the chart that I posted.


No, it isn't. Please think about that... You are adding two vectors that are not parallel, and the resultant vector depends, both in magnitude and direction, on the magnitude and direction of the component vectors that you're adding.

In our case, you have a 'natural wind', and also an 'observer-generated wind', due to the motion of the gyro. Those are the two vectors that you add, and the result is the apparent wind...
 

XXavier

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So what you are telling me is that during the start of the take off run, if there is a steady crosswind at 45 degrees to my right, that will become almost from 360 degrees direction by the time I'm airborne, (if I continue on the same path)??

Exactly...

A ground-fixed observer would see no change, but if you are a moving observer with relation to the ground, your perception of the wind will vary with your motion...
 

thomasant

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Exactly...
I still don't understand that. If I have to give an initial control offset for a crosswind takeoff, I do not change that offset till I'm airborne and changing my direction. If I were to follow your explanation, then I would be constantly taking off the offset to cater for the apparent change in direction of the wind during the take off. In which case I would be drifting to the side along the actual direction of the wind.
 

Jean Claude

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All that I understand is that a headwind will shorten my takeoff, and a crosswind will lengthen it.
This which lengthens your run in crosswind conditions, is the unfavorable action of the cross tilting of the stick.
No matter what the FAA says
 

thomasant

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This which lengthens your run in crosswind conditions, is the unfavorable action of the cross tilting of the stick.
No matter what the FAA says
I have no problem with the take off being lengthened, as long as it is safe and keeps me aligned correctly.
 
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