Takeoff in strong crosswind.

Jean Claude

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Recently in France a gyrocopter Calidus lay on its side because of a divergence of the flapping of the blades. Fortunately the pilot was not injured. He said, "I sure putting the stick completely on the side where the wind was coming in. Maybe not totally backward: I do not remember."
My opinion is that it's a mistake to push the stick all the way to the side: The angle of attack of the rotor offered to the compound wind during the run became much too low for a sufficient acceleration of the rrpm, even with the stick simultaneusly on the back stop.

I'm sure Mike's device would have avoided this accident by shouting "Stop stop stop stop" in the helmet immediately the full throttle was given.
 

Vance

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My suspicion is the pilot did not have the cyclic all the way back and let the indicated air speed get too high for the rotor rpm.

I have taken off many times in more than a twenty knot direct cross wind and I have never had the cyclic all the way into the wind.

When she lifts off I can tell if I had the correct amount of cyclic in because she will lift off without moving laterally.

If the wind is from the left and she moves left when she lifts off I had too much left cyclic in; if she moves right I didn’t have enough left cyclic in.

In my experience with a left cross wind if I have left cyclic in at the beginning of the takeoff roll the spool up with take longer and the takeoff roll will be longer.

I only use left to keep it simple and consistent although a cross wind from the left is the most common at many of my local airports.
 

JETLAG03

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Novice observation. My instructor explained to me that with my flexwing I adjusted the angle of the wing on both taxi and initial takeoff run not fully to the side but partially gently bringing it back closer to neutral as the wing began to take the load and that I should follow the same principle with the rotor, except when the wind is directly from the rear on taxi then forward and left. Do you agree, and if so how much does this differ between static rotor and one turning at roughly 100rrpm. Silly question probably, but cheaper to ask than find out I'm wrong the way. Phil
 

Jean Claude

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To avoid hitting their stops, the blades need a limited RPM / Forward speed ratio.
This ratio is not reached during the run at full throttle and stick full back, if the recommended pre-launch is respected.

But the hammering can still break the gyro by strong crosswind despite the same prelaunch, when the stick full back and side.
The stick on side is a bad option !

The explanation is in this sketch:
Sans titre.png
 

mark treidel

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Jetlag03
Your analogy is essentially correct in theory but there are still subtle differences between (you assume) a spinning rotor
and a trike wing. First, I personally do not taxi with the rotor spinning. I keep my blades fore/aft until I get to the hold
bars of the intersection where I enter the runway prior to takeoff. The only time I taxi with the spinning blades is after
landing while exiting the runway. As with a trike wing, one keeps the spinning rotor angled (tilted) only enough into the prevailing
wind so as to not allow enough air under the disc to 'lift the wing'....as in the trike; a delicate balance learned by experience.
In the trike, in a strong crosswind condition, if wind gets under the wing, it will cause a violent reaction almost jerking the control
bar out of your hands. That's why you keep the wing tilted to the 'point of least resistance' during taxi or roll out. There is no valid reason (in my opinion) to be flying a trike if the wind is that strong. Also, the control bar in the back position to keep the wing 'flat'.... opposite input for the gyro is full forward stick to keep the disc flat. Same thing we call 'rotor management'. One learns to always 'chase' the 'sweet spot'. After a time, the adjustments become second nature but the wind sure has a way of reminding us.
 
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WaspAir

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You also have the option of angling your ground roll path into the wind to reduce the crosswind component and gain a bit of free airspeed for a shorter roll.
 

Vance

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Novice observation. My instructor explained to me that with my flexwing I adjusted the angle of the wing on both taxi and initial takeoff run not fully to the side but partially gently bringing it back closer to neutral as the wing began to take the load and that I should follow the same principle with the rotor, except when the wind is directly from the rear on taxi then forward and left. Do you agree, and if so how much does this differ between static rotor and one turning at roughly 100rrpm. Silly question probably, but cheaper to ask than find out I'm wrong the way. Phil
In my opinion there cannot be too much thinking about rotor management because poor rotor management is by far responsible for most of the gyroplane mishaps.

When I taxi with the rotor stopped I like to have the rotor aligned front to back because that is where the least wind loads are. I find if it is left and right the wind may get hold of the rotor and put high loads into the control system as I struggle to keep it straight.

When I taxi with the rotor stopped I prefer to have the stick full forward because that keeps it out of the propeller. I teach to have the cyclic full forward and right just so they have a place to put it.

On spool down above 120 rotor rpm I have the stick full forward and centered. Below 120 rotor rpm I have the stick full forward and full right unless the wind is from the left, then I have the cyclic full forward and left.

This is what I learned to teach from Phil Harwood.

When I began my rotor acceleration on takeoff I find the rotor spools up faster if I have the disk slightly tilted away from the wind and as the rotor speed increases I slowly move the cyclic so on lift off with a strong cross wind component the disk is tilted slightly into the wind.

I personally never know if I have the cyclic in the correct position for takeoff until I lift off. If she goes straight I know I guessed right. If I look like a drunk walking I guessed wrong.

Where I fly on the coast of California a strong wind is usually gusting so it is unlikely my guess will be correct and I will need to make adjustments on lift off.

Some of my clients have trouble learning that when she is on the ground she steers with the rudder and once she if flying she is controlled with the cyclic and the rudder is used for yaw control. They tend to have the disk tilted away from the wind on liftoff leading to a dangerous sideways movement across the runway on lift off. A gust could set us right back down leading to a mishap.
 

Vance

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To avoid hitting their stops, the blades need a limited RPM / Forward speed ratio.
This ratio is not reached during the run at full throttle and stick full back, if the recommended pre-launch is respected.

But the hammering can still break the gyro by strong crosswind despite the same prelaunch, when the stick full back and side.
The stick on side is a bad option !

The explanation is in this sketch:
View attachment 1145807
I am not clear about what you are showing Jean Claude.
When I lift off in a cross wind I have the disk slightly tilted into the wind so I will takeoff straight ahead.
I have found if I have the cyclic centered with a crosswind component I will not lift off straight ahead.
 

jm-urbani

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without a video it is really difficult to form a plausible opinion of what happened
again only trainning is the solution to avoid such issues
I don't have any cross wind on the aerodrome I am based on (montélimar LFLQ) , so I often go an other place where I can find cross wind and an instructor used to teach cross wind landing and take of
most of the aerodromes have 2 runways making it possible to trainning but not all,
 

Jazzenjohn

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<You also have the option of angling your ground roll path into the wind to reduce the crosswind component and gain a bit of free airspeed for a shorter roll. >
Like Waspair said, as the crosswind component gets bigger, I angle my takeoff to get more wind aid/reduce the crosswind component. I don't feel compelled to try to follow the runway centerline in my little gyro when there is a strong crosswind. If it is Extremely High, then I have to question whether to take off at all. Taking off is voluntary but landing is not. If the crosswind gets very bad after I take off, a no roll landing completely sideways to the runway is not very difficult.
 

Jean Claude

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I am not clear about what you are showing Jean Claude.
I shows that at the beginning of the run, the angle of attack of the rotor is -10 ° with respect to the airflow of 20 Kts. Then when the ground speed of the run is 23 mph, the angle of attack is only 5 degrees with respect to the airflow of 28 Kts, etc.
With a sufficient pre-launch to usually allow the run to full throttle, the acceleration of the rrpm is now too slow and the blade bumps his stops
Destroyed aircraft.

I don't feel compelled to try to follow the runway centerline in my little gyro when there is a strong crosswind.
It's also my opinion, but some pilots feel obliged to follow the runway centerline during the takeoff run.
 
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JETLAG03

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@Vance "When I began my rotor acceleration on takeoff I find the rotor spools up faster if I have the disk slightly tilted away from the wind and as the rotor speed increases I slowly move the cyclic so on lift off with a strong cross wind component the disk is tilted slightly into the wind."

Interesting that in the very initial stages you capture a little more of the prevailing wind then adapt a similar disc position to my flexwing position nearing liftoff.
 

DavePA11

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Wouldn’t correcting for crosswind with rudder linked to the front wheel be more of an issue in the Calidus than having the stick too far into the wind?
 

jm-urbani

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in europe we must have less then a couple of free castering front wheel gyros and we don't suffer any epidemic of cross wind landing and take off crashes ...

only in france we have 800 gyros and I have never heard of anybody having laid down his gyro because of the linked front wheel affecting his trajectory during landing or take off

during take off in windy conditions the front wheel will leave the ground in 3 meters at 10 km/h and will have no effect on the ground trajectory whatever rudder angle

when landing, a gyro must not roll on the runaway after it's main wheels has touched the ground, it is esay to learn to keep the front wheel light until the gyro has stopped, it is not touchy at all.

even if the front wheel touches the ground when the gyro has not completely stopped, if the pilot does not pushes nervously the rudder pedals the front wheel will get in the trajectory direction by itself coz front wheels are behind the axle or rotation of the fork

free castering front wheel is a good thing except in what it makes it possible for gyros pilots to land like a fw aircraft, in my opinion a giro must always be landed engine idle

IHMO a gyro must not be landed flying at 1 m over the Runway reducing the engine power gradually until the gyro touches the ground but only making a flare with no thrust, in france we are taugh to approach idle in final

it is probable that the bad reputation of rudder linked front wheels gyros comes from the fact that some american pilots used to Free castering FW have laid off europeans gyros landing them Fixed Wing style

I would prefer a free castering wheel for many reasons but in europe linked front wheels are not an issue at all

gyros have a 40 kg mass at the top of a 2,8m mast... it must not exceed 15 km/h on the ground max max...
 
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Jean Claude

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Wouldn’t correcting for crosswind with rudder linked to the front wheel be more of an issue in the Calidus than having the stick too far into the wind?
The pilot gave a very clear account of the flapping blades!
 

Tyger

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even if the front wheel touches the ground when the gyro has not completely stopped, if the pilot does not pushes nervously the rudder pedals the front wheel will get in the trajectory direction by itself coz front wheels are behind the axle or rotation of the fork
Are you sure that this is the case on the Calidus with regard to the position of the wheel on the fork?
 

jm-urbani

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the centering effect of front wheel can be obtained by different fork geometries, I am quite sure the calidus for is self centering
 

DavePA11

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I just wouldn’t think a flap can cause the gyro to tip over unless there is some other force contributing to it assuming the pilot recognized the flap and tried to stop it with the correct control and power changes.

Didn’t see this accident in the blog:
 

Vance

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I just wouldn’t think a flap can cause the gyro to tip over unless there is some other force contributing to it assuming the pilot recognized the flap and tried to stop it with the correct control and power changes.

Didn’t see this accident in the blog:
The retreating blade stalls and the advancing blade lifts and over she goes.
I have a great picture of this very thing but it is a mega bite PDF and I don't know how to post it.
 
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Vance

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Wouldn’t correcting for crosswind with rudder linked to the front wheel be more of an issue in the Calidus than having the stick too far into the wind?
All three Calidus I have flown wanted to self center.
I did not inspect the geometry.
Takeoff in a cross wind did not appear particularly difficult to me.
 
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