SSTjumbo
Topic Author
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Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 9:29 am

Today, I had to cancel a 141 stage check due to 30kt winds blowing directly across the only runway today. As I was going to my truck, I glanced at a Citabria turning left base and walked over toward the threshold (this is KLOT for any of you wondering). I stood just outside the fence and watched the plane come in, and as he was quarter mile from the field, I could have sworn his nose was pointing directly at me. When he hit short final, he was jack-knifing the controls like no tomorrow, and when he flared, I could tell he was mentally drained from maintaining the sideslip as he flared high and literally had a thirty degree bank input as he bounced onto the runway. Needless to say, he made a safe landing and was able to taxi off into the tailwind, but it prompted me to ask myself how much crosswind can say a Cessna 152 handle before you hit the floor with the rudder or you scrape the wingtip against the ground. Also, does max Xwind (not necessarily component) vary drastically among small aircraft?

BTW, my toughest landing was solo in a 152 with winds varying between about 030 from runway heading to 120 at 14kts gusting 21kts, so I've had my share of fun.
I don't know, so this is my signature.
 
flyf15
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 9:45 am

Could I push a 172 to a 25kt direct crosswind and have a successful landing? Probably.
Would I try? Thats a whole different question.

Reminds me of something we had happen at a small airport near my house one day. Pretty strong crosswinds and a Piper Cub ended up using one of the connector taxiways as a runway, ground roll of less than an airplane length. Called up the guys on UNICOM and they helped get him to a tie-down.

[Edited 2003-10-31 01:58:19]
 
VH-KCT*
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 9:56 am

I'd agree.

Maximum demonstrated crosswind component for say 172/Warrior is 15/17 knots. Legally if the crosswind is above this you must allow fuel for an alternate (Aus regulations).

However, I've done crosswind landings in crosswind 20 knots gusting 25 knots. Full aileron and 3/4 rudder travel on touchdown, but still possible!

 Smile
I am The Stig
 
POSITIVE RATE
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 10:01 am

The TB10 Tobago has the highest demonstarted X-wind component of any light single i've seen- 25 kts. It is possible to do it but who would wanna try that. Even heavy jets don't really like accepting a 25 kt X-wind unless they absolutely have to.
 
XFSUgimpLB41X
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 10:03 am

"Also, does max Xwind (not necessarily component) vary drastically among small aircraft?"


Something to note...it is not "max crosswind"...it is "max demonstrated"..big difference. Most cessnas and warriors that I've seen have a max demonstrated of around 17 knots. Can you land in higher? Definitely...I certainly have upped that by 5-10 knots on several occasions.

My suggestion to you is....if you have reservations about doing it, don't! The only reason why I landed in a higher component than "demonstrated" is because I was comfortable in the situation and the airplane. I limited my private students to 7 knot crosswind components- for good reason. Most people don't get a good mastery of crosswind landings until they have well over 100 hours, or more.

However, when I was with my students, most anything would go as long as I felt safe and they weren't about to poop their pants (no one is going to learn anything if they are scared out of their minds).

Just because there is a said limit in the airplane doesn't mean you need to go all the way to it. Use good judgement and work your way up to harder levels gradually, which is the reason why your stage check was cancelled today (remember- if it is that windy down low, it is going to be bumpy as hell up in your maneuvering altitudes also- wouldn't have been the best day to hold the airplane within tolerances for a checkflight).
Chicks dig winglets.
 
Guest

RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 10:39 am

"...but it prompted me to ask myself how much crosswind can say a Cessna 152 handle before you hit the floor with the rudder or you scrape the wingtip against the ground."

That's acutally a really good question. Would I ever like to personally find the answer to that question? No, not really. I'd rather let some test pilot find that out for me. But it would be interesting to know just exactly how much crosswind the airframe could physically take without scraping important pieces of aluminum.

I certainly wouldn't fly in 30 knots of direct crosswind, though. And to land a taildragger in that type of conditions? I don't envy that pilot. I'd seriously consider landing on a perpendicular taxiway or something. Let's see, 152 approaches at 65 kts, and with a 30 kt. headwind, that makes a ground speed of 35 knots. Ought to be able to stop it quick...

-Normal

[Edited 2003-10-31 02:41:10]

[Edited 2003-10-31 02:44:25]
 
aaron atp
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 10:59 am

While it's not a 152, I've done pattern work in a C172RG with a steady 35 knot crosswind (CA central valley). The most flaps I was able to do it with was 20 degrees (that was the first landing), after that no flaps were used.

Touchdown speed was >=85 knots (what's that, touching down with an extra 25 knots without a flare?). Full deflections for aileron and rudder went in about 10 feet AGL (IIRC), after that, I just forced it onto the runway. I probably did 6-7 of these circuits without any go-arounds (although I came real close to one on the first landing).

The key was the fast approach/touchdown speed. Anything below that would have been impossible. My fastest touchdowns would have been in the 95 knot range. If you can't imagine why, think of the normal touchdown speed and the wind as vectors. You just can't swing a 172 the needed 35 degrees for touchdown at normal approach speeds. At the high speeds I was at, you only needed to fly about 20 degrees off the wind for touchdown. Keep in mind that the winds were higher aloft, so the approach was flown even faster

Aside from that, I've hung off the wing of a few taildraggers and even a 152 in about that same wind speed trying to get them off the runway after landing into a headwind.

Okay, do as I say, not as I have done: Please don't kill yourself trying to do those kind of landings. That was the peak of my Cessna flying skills, never was better, never will be again, and never will try (although I do have some other feats that top these). I digress, sorry.

Anyway, you asked for a maximum, and I would put it at ~35 knots for the C172RG. The point is, by increasing your approach speed in a light A/C with no flaps you can get the thing on the runway without damage. The taxi is a different story.


aaron

Flame Away... I was young and stoopid. (but I enjoyed it)
 
Guest

RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 11:05 am

Crosswinds are basic aerodynamics...
How much crosswind, I will not figure that, but some numbers here for you...
xxx
First of all, crosswinds are NOT limitations... They are "demonstrated"...
Obviously, if you bend an airplane, by landing at higher numbers, you are now flying in a manner that can be construed as reckless... If you survive, ok...
xxx
The 747 - yes - big airplane, and most of the airliners I flew before, mention a 30 kts crosswind "demonstrated" figure... I personally find the difficulty in a crosswind landing to be a function of what your approach speed Vref is, and what the wind is... When approaching at say, 140 kts, the crosswind gives you a "drift" of some 12.3 degrees... If you are light and slow down the 747 to 120 kts, that drift now becomes 14,5 degrees...
xxx
The little airplane I own, is a L-21 (a military version of the Super Cub). I use generally 55 kts as Vref. If there is a direct 30 kts crosswind, the drift when landing would be a whopping 33 degrees...
xxx
Crosswind limitations consideration should be, what amount of drift you can consider to use, during the flare and touch down. Obviously, you can handle some amount of extra crosswind with a high wing aircraft, I call it the "Chinese approach" - wan-wing-low... In the 747, you dont want to bend your outboard engines, and in a low wing aircraft, that low wing does not permit you much...
xxx
I personally would keep the L-21 (or a Cessna 150/172) to a limit of 15 to 20 knots if you are sharp... and add an extra few knots on your Vref, so to be able to decrease the amount of drift...
xxx
In extreme crosswind conditions, with the L-21, what I do in the flare and touch down is to immediately bring flaps UP... and give a full "stick" deflection into the wind at the same time, this to absolutely kill any possible "lift" from that nasty crosswind... Since it is a taildragger, I also watch out to keep the tail high until the plane settles down by complete lack of airspeed...
xxx
Even in a 747, a 30 kts crosswind is not that easy to handle - I once landed a DC8-63 in extreme crosswind conditions, was 40 kts gusty 70 kts, and some 60 degrees OFF the runway... I scraped the bottom of the cowling of #1 engine... but I had no other place to land... damage was just sheet metal by chance, and some 250 nervous passengers...
xxx
Fly safe - Happy contrails  Smile
(s) Skipper
 
Woodreau
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 12:36 pm

I've had the same mentally draining experience as you described for the other pilot.

I was flying a Diamond Katana landing on Rwy 15 with winds 180-190 at 20kt, gusting to 35-40.

Looking back, I should have never started the Lycoming engine, but I decided to go anyway. I get airborne, and instantly I regretted leaving the ground because the gusts were just throwing the Katana around. I ask to stay in the pattern and just land. Get cleared for landing. I remember having an extreme crab in to just track down the extended centerline.

The aircraft has an approach speed of 52kts and a stall speed of 34kts.
Because of the slow groundspeeds involved, I remember being high when I turned from downwind to base and from base to final. I turned base very close to the threshold. I don't remember what speed I was trying to maintain, but about 55-60kts indicated, but I wasn't get more than 30-40kts ground speed once I turned final. All I know is that the runway wasn't coming towards me at the speeds I was normally used to.

I distinctly remember looking over the left edge of the canopy to look down the runway and when I faced forward I was looking right at the guys in the control tower. And I imagined them saying, "Hey, Verne, look at what this idiot is doing..."

It was very much flying the aircraft all the way onto the runway and even after landing until I was tied down again. But I got out of the aircraft with knees knocking and a very dry tongue.

But anyways, the crosswind limitation is not really the aircraft, it's the pilot. Only you know what your limitation is.

Woodreau / KMVL
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
Guest

RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 1:38 pm

Pop Quiz...

Q1: In cases of extreme x-winds, is it legal to operate off of a taxiway that is aligned more favorably with the wind?

Q2: If so, how will the tower controller clear you to takeoff or land?
 
flyf15
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 1:48 pm

Jetguy...no, not legal, unless an emergency has been declared and it is absolutely necessary.
 
Guest

RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 2:05 pm

Chris,
Is that your final answer?
Jetguy

 
flyf15
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 2:14 pm

Well, its one of those things where you are sure you know the answer, but are also sure you're going to find out you're wrong.

But, the one thing that makes me sure is that you mentioned "to takeoff" in the second question. Landing I could see happening, takeoff on the other hand...no.

So yes, it is my final answer.
 
Guest

RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 2:26 pm

I will eliminate the phrases "In cases of extreme x-winds" and "that is aligned more favorably with the wind" and simply ask the question: Is it legal to operate off of a taxiway? Can a controller issue you a clearance to either takeoff or land on a taxiway? Can operations be conducted without a tower clearance to takeoff or land? (Assuming the tower is manned and operational.)

Jetguy

 
pilotpip
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 2:39 pm

Hey Positive Rate.

The TB-9 has the same max demonstrated x-wind. I've done it at 30. It wasn't fun, it wasn't pretty, but I landed it. Why did I do this? The thunderstorm that was right on my tail. Would I do it again? NO!!

SSTjumbo, I'm surprised you didn't witness that citabria groundlooping. That was either a very good or very lucky pilot.
DMI
 
flyf15
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 2:39 pm

For that question, I'm still going to go with no. As long as we're talking about airplanes (not helicopters or anything) and no special circumstances (closed runway, fly-in, emergency, the taxiway being an approved runway, ...). For non-emergency operations from taxiways, I'm going to assume it takes some action by the local FSDO and a NOTAM or two.

So, for normal day-to-day operations in airplanes, I'm going to say no, it is not legal to operate from taxiways, nor can a controller issue you a clearance to land on a taxiway.

[Edited 2003-10-31 06:42:21]
 
SkyGuy11
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RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 3:27 pm

For some reason I remember that it is legal. On the other hand, you'll be slapped with careless and reckless if / when something happens.
.
 
Guest

RE: Xwind, How Much Can You Push A Small Aircraft?

Fri Oct 31, 2003 3:54 pm

I'm going to hold off posting the answer. I think I'll post the question in a separate "pop quiz" thread to see what the response is.

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