Cross wind landing techniques

[mak]

I have been reading a bit about causes of aviation accidents and also about gyro specific accidents lately. Obviously human error is on top of the list and I include wire strikes and CFIT under this, even though in some instances this might not be the case. The three other major factors are blade flap, loss of rotor RPM in flight (a scary prospect that I would like to discuss and get some advice on later) and wind, mostly on landing. I see in a lot of accident reports things like “a sudden downdraft”, “a sudden gust of wind”, “loss of directional control”, etc, etc. Are we as gyro pilots so spoiled by these magic wind resistant machines of ours that we sometimes neglect to assess the full possible effect of the wind, especially on take-off and landing? Do we really anticipate the downdraft of the wind coming over the hanger, or the lack of lift as we decent behind the trees, or the “sudden gust” as we come out behind the hanger into the open?
Something that I have learned from an experienced flying buddy of mine is his constant awareness of the wind direction and affect, knowing when to expect lift and downdrafts as well as preferred landing direction in case of an emergency. Another interesting principle that he applies, not sure if all chopper pilots do this, is flying 500ft AGL against the wind and 700ft AGL downwind. Do we as gyro pilots consider this wind effect when flying at tree top or at 300ft and what difference the wind direction will make to an emergency situation, our glide ratio, our landing roll, loss of altitude to turn into the wind to land or does wind direction only mean a lekka tail wind or @#%& head wind for us on cross country trips.
Actually the amount of wind related gyro incidents should not be surprising. We fly in high wind when a lot of fellow aviators might choose to keep their aircrafts in the hangers and we land at low or zero speed when we might be at the greatest risk, to all the above mentioned factors, without or with limited rudder authority.
How do we avoid these incidents? Obviously we need to be aware and anticipate the above mentioned wind affects but also with good cross wind landing technique. But what is the best cross wind landing technique?
I hear guys saying that doesn’t matter how big the cross wind component you land as per normal, obviously with your rotor into the wind to track centre line and with rudder input to keep you straight. This way you know how much control & rudder input is needed to maintain centre line. You will lose most off or all rudder authority just before touchdown and stand the risk of being turned sideways, but this will not matter as your speed is at zero.
Others promote the crab approach to maintain centre line and to pull the gyro straight with rudder input just before touchdown. The risk here is getting the timing and amount of input right as you almost only have one chance. Rudder input too early and you will drift from centre line and need to correct with stick input. Too late, too much or too little input and you might touchdown sideways. Again they say this should not matter as your speed should be at zero.
But what if you don’t get it 100% right and your speed is not zero?
Others promote coming in faster and with more power than normal and touch down faster and not to attempt a zero speed touchdown. This way you always have rudder authority, even after touchdown and will be assured of a straight landing. I suppose this fits with Jim Davis’s theory that in some circumstances you can attempt a greaser of a landing and in others it is better to “plunk” her down on the runway as quick as possible. The only risk here with forward speed and with an angled nose wheel (to adjust the rudder) at touchdown, is keeping your nose wheel of the ground for as long as possible or to straighten it as quick as possible.
Others say come in with more power than normal and it is safe to do a zero speed touchdown.
The other day I also heard someone saying you must come in higher than normal and dive onto centerline as it is easier to dive onto centerline than try and maintain it during normal approach in cross winds. I must admit, I haven’t tried this one yet.
Hopefully the experienced pilots and instructors can help me out here. What technique do you guys prefer and teach your students?
Just for interest, does everyone have a favorite cross wind direction preference and do you choose your landing direction accordingly. Some might prefer the wind coming from the left to push the stick left against the wind and apply right rudder as per usual take-off procedure (my preference) and others might prefer pulling the stick right into the wind and applying left rudder. Do you consider this on a full cross wind landing if any runway direction will suffice?

[saraf]

Hi Mak,

I will try explain how i teach cross wind landings in the RAF.
I do think however there is a big differance between the differant gyros and how cross wind landings are taught.
I have also seen allot of accident reports indication , "emergency landing whereafter gyro colided with wires" nothing about the door coming off that caused the emergency in the first place. So what is indicated in the report is not allways what happend...........
Ok back to the cross wind landing, in the RAF a crosswind is not such a big issue as we do not have such a big horizontal tail surface with winglets that makes crosswind landings more difficult. Firstly I let the student crab in with the approch, this to me makes then consentrate more on the landing at hand than the wind, which may be a bad thing but it works as this keeps there mind off " o shit i have to do a crosswind landing" then after the first flare 10 feet off the runway i let them kick the rudder to correct the crab or yaw, the sttudent allready had from the approch to put some stick pressure in to keep the gyro on centre line so this is one issue some what out of the way. 10 feet off the ground he starts the level off. Execute a normal landing with full flare 3feet off the deck , we land the RAF on the back wheel so we do not have the problem of the front wheel then beeing off centre and we keep the stick back until the RAF stands still, then only stick forward.

If the wind is to strong cross land in the width of he runway.......ooooooo upington may be the only runway that is 50m wide:)
But yes this is my way and it seems to work, other gyros are differant and need differant training.
One thing that does bother me is that there is allot of other gyros that get blade flap. I do have my own opinion why this is happening, and it has on my opinion more to do with the rotor type than the pilot.

Regards eben jnr

[BONZAI BELL]

Eben
I would like to hear your opinion on blade flap . You mention that it has to do with rotor type , rather than the pilot.

[saraf]

HI Swannie

Firstly if you look at the gyros that has the most accidents resulting due to blade flap..........gyros with light rotor systems and gyros with rotor systems that the blade profile struggles to "accept" airflow at low RPM. (sounds unreal but you get blade profiles that accept airflow better and easier than others.)

Light aluminum blades spin up very quickly , but slow down just as fast and struggle to keep inertia. Combined with a pre rotator system that the stick can not be pulled back and the take off run commenced. To give you an indication: Gyro pre rotating , stick forward up to 200rpm , disengage the pre rotator on the dash ( some gyros has this unit on the dash) or even in your hand. Stick back , brake off , full power. In the 5 seconds it takes you to do this, light blades will decelerate below 170 rpm or even below 150rpm, I have seen and experienced this myself. The blades are unloading at this moment and now you are hammering away the power on blades that is unloading, not a good thing... You would rather want the blades to be loading and then ad the power,( the only way to do this is , is to start the take off run slowly and see that the blades is increasing in rpm) this eliminates an onrush of air being pushed through a rotor system that is unloading and that does not accept airflow that easily.

Your gyro has very heavy blades , thus more heavy on the stick and keeps inertia better, plus you can pre rotate with the stick fully back while commencing the take off run.... Thus resulting in less blade flap accidents, the same with the RAF 2000. IN the RAF I have pulled the stick back at 70rpm , added the power gradually with no problem.........all due to the RAF rotor system accepting airflow very well as well as a tip weight to keep that inertia thus making blade flap an non event. This does not eliminate it at all and still training is needed for a student. RAF has not had one blade flap incident in SA or that I know of.


HOpe this explains some of my views........

Regards
Eben Jnr

[BONZAI BELL]

Thanks Eben
I understand where you are coming from. What i have taught myself was , once i disengage my pre-rotator with stick full back position , i only apply half throttle for a while and make sure the rotor speed picks up . once my rotor rpm is plus minus 250 , i gradually apply full power ( without turbo ) 35 man. pressure.
With this method i use a bit more runway , but i am comfortable with it. i normally get airborne at approx. 50-55mph

[saraf]

That is best practice and by doing this you will never have blade flap. I do however recommend if the the gyro can to keep the pre rotator engaged while commencing your take off roll.

[Rudix]

i gradually apply full power ( without turbo ) 35 man. pressure.

At 35" man pressure you are using the turbo! Maybe not full boost but you are boosting.....

Fly safe,
Rudi

[mak]

Thanks Eben

Yes, I suppose it is gyro dependant and especially so on the RAF with its different landing technique. I prefer a bit of forward speed and thrust to counter any possible cross wind effect.

[saraf]

No Prob Maruis, hope I could be of some help...

Regards
Eben Jnr

[jj le roux]

Mak great topic just a pity it went into a different direction. Interesting none the less I'd still like to hear what Len and the boys in CT think aswell??

[Centu Gyro]

Not sure if I should commend or frown…

http://www.youtube.com/watch?v=y5zWLTQXcUI

[Pieter Smith]

Not sure if I should commend or frown…

http://www.youtube.com/watch?v=y5zWLTQXcUI

Skies, maar ek het nou my g@t af gelag!!!!!!!!!!!!
Thx!

[Low Level]

Eeeish Jacques. Waar het jy die footage van my landing Saterdag gekry?

[BONZAI BELL]

Wanneer het jy die Sycamore op n dieet gesit?

[Centu Gyro]

Daai gyro Land Cruiser van Leon lyk maar so maer op die Brits vlaktes tussen al die heat waves...