How Much Cross Wind to Run Out of Rudder?

[201er]

As we all know, demonstrated cross wind component doesn't really mean anything. It is what the manufacturer happened to demonstrate but does not mean or imply a maximum. The real max-crosswind capability is where there is no more available rudder to make a side slip without drifting (or where the upwind wing runs out of ground clearance). What is that max?

It is likely different between long, mid, and short bodies. And among short bodies there is probably a difference from when they expanded the rudder. Share your knowledge or experience of what that maximum is and specify the specific model it applies to.

[N201MKTurbo]

I haven’t flown in strong winds on a daily basis since I left Denver in ‘89. I seem to recall it is around 35 KTS where you run out of rudder. 

[Hank]

I've yet to find it. The highest i remember was at KRAP, gusting around 25-27 knots, 50° left of the runway.

I took my IFR checkride at KCRW, using Runway 23; seems winds were on the order of 15G23, VAR 230-320. I passed . . .

[Fritz1]

On a long body it is somewhere between 35 and 40 KT, landed at KIAD RWY 01 with 35 gusting 40 Kt from 270 about a year ago, runway is 150ft wide, lined up with one of the high speed taxiways, use full flaps, reduces the risk of a stall or tail strike in gusty conditions, started on the right side of the runway and traversed it to the left towards the high speed taxiway, nobody complained

[Andy95W]

Depends on airspeed.  More airspeed = more rudder authority.  One of the reasons partial flaps helps.

If you can keep your speed up sufficiently and fly it on to the runway, you’ll hit the wingtip before you run out of rudder.  Misjudge and you’ll balloon viciously.

Realistically, though, I agree with Rich.  About 35 knots.

[Paul Thomas]

I've seen these type of threads on multiple forums and while our Mooney do well in X-wind, I still don't like these threads. Some members misremember or exaggerate the numbers and mislead others about the capabilities of the airplane.

Touching down is the easy part... slowing down and taxing in are the real challenge. The closest I've ever come to damaging an airplane was getting out of a C140 when a gust almost took the airplane into the hangar door.

The bigger the number, the more questionable becomes the judgement if you damage the airplane. My suggestion is to use a number you're comfortable with or divert instead of going by someone's max number on the internet.

[PT20J]

I once asked Bob Kromer (Mooney factory test pilot) why the demonstrated crosswind velocity was so low and he said that the older test pilots all cautioned to be conservative because not all pilots have the same level of proficiency and most don't often practice crosswind landings. He had a personal max crosswind number that he said he was comfortable with when he was flying Mooneys nearly daily. I don't recall the exact number but it was way less than 35 knots. Somewhere in the low 20s I think.

[EricJ]

10 minutes ago, PT20J said:

I once asked Bob Kromer (Mooney factory test pilot) why the demonstrated crosswind velocity was so low and he said that the older test pilots all cautioned to be conservative because not all pilots have the same level of proficiency and most don't often practice crosswind landings. He had a personal max crosswind number that he said he was comfortable with when he was flying Mooneys nearly daily. I don't recall the exact number but it was way less than 35 knots. Somewhere in the low 20s I think.

I've always heard that the "demonstrated" number is just the highest crosswind observed during a particular portion of the certification testing, so it is just dependent on what crosswinds were present or available during testing during that phase.   In other words, "we saw this value actually demonstrated", which is a useful data point, but also why it isn't a limitation.

[PT20J]

42 minutes ago, EricJ said:

I've always heard that the "demonstrated" number is just the highest crosswind observed during a particular portion of the certification testing, so it is just dependent on what crosswinds were present or available during testing during that phase.   In other words, "we saw this value actually demonstrated", which is a useful data point, but also why it isn't a limitation.

Bob told me that at Mooney, the number was up to the flight test engineer. They flew a number of flights and then chose a conservative number that they felt the "average" pilot wouldn't get into trouble with. One of the issues with the Mooney is that the nose gear is rigidly connected to the rudder pedals so you have to release pressure and let the rudder center when the nosewheel touches down while simultaneously increasing aileron into the wind.

[47U]

9 hours ago, 201er said:

Share your knowledge or experience of what that maximum is and specify the specific model it applies to.

Short body, short rudder.  Last week I landed on RW17, 75’ wide.  Wind was 240 degrees, 17kt G22.  And it was gusty.  I elected no flaps for the higher speed.  It was sporty, but did not feel unsafe.  Yeah, it skipped a couple times with the excess airspeed, but I road the upwind wheel for a bit and it settled down fine.  Skip @PT20J is right, the nose needs to be centered when it touches down.  I did pretty good, but it wasn’t perfect.  

[N201MKTurbo]

The question wasn’t what is smart or prudent. Everybody needs to figure that out for themselves. 
 

Back when strong crosswind landings were a daily occurrence, if I couldn’t track the runway with the rudder pinned to the floor, it was time to find a better runway. 
 

The OP asked a question. I answered it as best I could.

Also, I never carried extra speed. I wanted that airplane to be done flying when the wheels touched down. As has been mentioned, if it takes extra speed to control the plane, you will lose control of it as you slow down. If you cannot track the runway, it is time to go around.

[hazek]

2 hours ago, N201MKTurbo said:

Also, I never carried extra speed.

Everyone carries extra speed. Some foolishly add extra to the extra to be "safe".

[aviatoreb]

Some are reporting the angle here, or implicitly doing so by reporting the wind direction and runway direction, but I want to remind just in case.  I know a lot know but just in case, entertain this old math professor -

30kts at 60 degrees is a lot less than 30kts at 90 degrees.  30*sin(60)=25.98 which is a bit less than 30 if it were at 90 degrees and a lot more than 30 if it were at 45 degrees 30*sin(45)=21.21.  So remember to pay attention to angle when considering.  My personal absolute max is 20 degrees in the perpendicular component.  So 30kts cross wind is ok if it's at 40 degrees.  30*sin(40)=19.28.

[Hank]

10 minutes ago, aviatoreb said:

30kts at 60 degrees is a lot less than 30kts at 90 degrees.  30*sin(60)=25.98 which is a bit less than 30 if it were at 90 degrees and a lot more than 30 if it were at 45 degrees 30*sin(45)=21.21.  So remember to pay attention to angle when considering.  My personal absolute max is 20 degrees in the perpendicular component.  So 30kts cross wind is ok if it's at 40 degrees.  30*sin(40)=19.28.

Tru dat, and both my phone and tablet have a calculator, but I'm not looking down long enough to use it (maybe if it had buttons I could feel?).

I read somewhere one time a little thing to approximate the crosswind component:

• 30° off runway heading = 1/2 windspeed
• 45° off runway heading = 2/3 windspeed
• 60° off runway heading = windspeed

This is mental math that I can keep track of, and it's close enough to keep me safe. I rarely fly when winds are > 20 knots on the ground anyway, just lucky I guess. (And I've only been to Wyoming in my Mooney the one time   ).

[aviatoreb]

3 minutes ago, Hank said:

Tru dat, and both my phone and tablet have a calculator, but I'm not looking down long enough to use it (maybe if it had buttons I could feel?).

I read somewhere one time a little thing to approximate the crosswind component:

• 30° off runway heading = 1/2 windspeed
• 45° off runway heading = 2/3 windspeed
• 60° off runway heading = windspeed

This is mental math that I can keep track of, and it's close enough to keep me safe. I rarely fly when winds are > 20 knots on the ground anyway, just lucky I guess. (And I've only been to Wyoming in my Mooney the one time   ).

Exactly - 

I dont actually compute with the trig functions to two decimal places of accuracy on an irrational number when I am flying.

My main point is I sometimes get the feeling that some people speak of cross wind across the runway that is a fierce 30 knots and they land it but actually its 45 degrees off perpendicular so they didnt really land a 30 knot cross wind and then they tell themselves it was fine and then another time it really is 30 degrees 90 degrees off and they are expecting it to be the same relying on mistaken math.

[201er]

4 hours ago, aviatoreb said:

 

I dont actually compute with the trig functions to two decimal places of accuracy on an irrational number when I am flying.

 I’m disappointed, I expected at least to one decimal point from you. Show your work next time.

Edited 18 hours ago by 201er

[Hank]

37 minutes ago, 201er said:

 I’d disappointed, I expected at least to one decimal point from you. Show your work next time.

Be careful, Mikey. He might post the next million digits of pi . . . . .  

[exM20K]

I’m in “Fly the Approach and Find Out” camp.  I think the kids call this FAFO.

The runway itself is also a decision factor.  2500x30 vs 5000x100.  Big difference in the time available to execute a graceful touchdown.

And, don’t forget: the anenometer may well be mounted at the FAA’S preferred 10 meter height, not the 2ish meter altitude where the flare begins. And the ATIS is, on average, 30 mins old.

-dan

[midlifeflyer]

8 minutes ago, exM20K said:

I’m in “Fly the Approach and Find Out” camp.  I think the kids call this FAFO.

LOL! I was doing a night currency flight in a Cessna 152. Winds were howling from the west for runway 17. As I turned base to final I saw there was no way I was going to be able to land that time around.

ATC: Cleared to land runway 17.
Me: I don't think so.

[A64Pilot]

Crosswind capability depends on gross weight, speed, power applied and even on which side the wind is coming from, obviously if your carrying power as surely most all of us are in a cross wind landing then you need a little right rudder and that cuts into what’s available, wind from the left does just the opposite.

Additionally most every aircraft I’ve been around has a range of allowable rudder travel, if yours is at the min then you have less rudder authority than one that’s at the max

So we end up in most of GA aircraft rather conservative cross wind numbers, there are some exceptions to this of course, Gulfstream killed a couple of test pilots and crew with a rather ridiculously difficult short field takeoff procedure because they wanted to advertise that the G650 could get into and out of very short fields, so they had no “fudge” at all. 

https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1202.pdf

Long and short of this is that crosswind capability is very variable, oh and I forgot grass runways too, grass is much more forgiving if you don’t touch down perfectly straight  so cross wind landings are easier on grass, so add that to the list.

Edited 10 hours ago by A64Pilot