Aerodynamic Reason for 3-pt Crosswind Landing?

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merrymunks
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Aerodynamic Reason for 3-pt Crosswind Landing?

Post by merrymunks »

Recently my IFR CFI and I were landing in a direct crosswind, 9mph gusting 12. I chose a 3-pt, which led to a lively discussion on the merits of using a wheel landing under such circumstances. One of his training aircraft is a Pacer, which I got my TW signoff in. He maintains that the Pacer is one of the squirreliest planes to land in a crosswind, and he uses a wheel landing when it's not blowing straight down the runway.

His question: WHY is a Maule more challenging to do a wheel landing in under crosswind conditions than any other tailwheel aircraft? He wants the aerodynamic explanation, not just "it's not recommended." He pointed out the Maule's large vertical stabilizer in comparison to the Pacer's, we discussed the blocking potential of both aircraft when in 3-pt attitude, and I must say I'm now curious as well. Just added up my logbook landings, it's at 424 in my M5-180C, and probably less than 20% have been wheel landings.

Thanks in advance for any insights.

-Heather
M5-180-C

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andy
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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by andy »

How about a physics explanation? Has he weighed the tail wheel of the Pacer vs. the tail wheel of the Maule? I weighed my MX7-180's tail wheel once with full mains and no other cargo. It came in at 250 lbs. That's a lot of mass at the end of a 20 foot lever arm. Rudder corrections to prevent a ground loop in a crosswind have to be done sooner before the force exerted by the crosswind pushing against that mass is too great to control without a dab of brake. Touching down on a hard surface with any sideways drift will whip that mass in the wrong direction and rudder correction may not be enough to counteract it.

In a wheel landing there is a smaller pivot point (one or two mains) than a 3-point landing. The tail wheel opposes pivoting in a 3-pointer until it breaks loose.

I think the answer to your question is that the larger vertical stabilizer makes it more susceptible to a crosswind. The heavier tail makes it more challenging to overcome sideways movement. The larger mass of the tail makes a wheel landing pivot more readily than a 3-point landing.

I always do a tail-low wheel landing now unless I have to stop really short. Most of the time I'm landing on grass to preserve my 4-year-old bush wheels so it can be bumpy. I like to keep the tail wheel up as long as possible to minimize the beating it takes. A tail-low wheel landing lets me approach at a slower airspeed and land shorter. The other day I landed in the grass beside the hard surface runway at an airport that I haven't visited in a while. The FBO mowed a fairly wide strip of grass before the threshold of the hard surface but then reduced it to a narrow strip that ran too close to the runway lights for comfort. It wasn't obvious from higher up. I ended up having to put the tail down quickly and apply the brakes to stop in about 300 feet so I wouldn't plow into 4 foot high grass that might conceal all kinds of problems. The nice thing about a tail-low wheel landing is that you can convert it quickly to a 3-pointer if necessary.
Andy
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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by maules.com »

It depends a bit on tyre size, or standard length gear versus extended.
The Maule is designed with an angle of attack when in three point condition and on smaller tyres so that it cannot stall at takeoff.
Stall speed full flaps might be 45mph but the wing does not lift from on ground three point angle of attack when on small tyres until about 53+mph.
So, one can reverse that to a landing situation instead of takeoff, and see that below 53mph the tailwheel will touch first before the mains which produces the Maule ker-plunk full stall landing. All that is an aside to the question but does come into play.
The Maule especially the M5 is very predictable and agile in a cross controlled landing. One can practice on a good long runway by traveling the length on one main wheel, then on the other main wheel. Do it first from takeoff but don't lift off until there's no runway left. Try different speeds and flap settings. Eventually you will have the sight picture and be able to perform good steady crosswind landings.
M5 shorter wings allow it to be on one wheel and have a good low wing condition. In my past I have been known to demonstrate to a reticent pilot that you can be on one wheel and touch the tip on one side then roll onto the other main and touch the other tip. He had already touched (by mistake) both droop tips and was looking for help.
Be positive with the plane, decide what you want to do and make the airplane do it. It will respond.
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LCDRLES
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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by LCDRLES »

With our M5 180C in windy West Texas we tackled some pretty stout crosswind landings (15-18kts) with a tail low wheel landing with the wing lowered and touchdown on one main.
I think this is just what Jeremy described, much more eloquently than me.
The practicing by flying down the runway in a crosswind is key.
Great advice.
1984 M5 180C, N5654B
1956 Cessna 180, N4971A
1977 7GCAA, N1165E

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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by merrymunks »

Thanks all for the excellent insights. The tailweight is a factor I hadn't considered. I will start with the 1-wheel practice and see if I can get a better feel for it in calm conditions before attempting with an actual crosswind.
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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by montana maule »

I don't have any time in a Pacer so I can not compare between that and a Maule. I do have a fair amount of time in Maules. The only way I land in gusty and / or crosswinds is in the wheel landing attitude. Here is a video of some instruction in winds 45 degrees off of the landing strip gusting in the 20's. The airplane used during the dual instruction was an M5-180C.
https://youtu.be/q82H0kV4sxU www.montanabyair.com

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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by HeavyLoad »

montana maule wrote:
Wed Sep 09, 2020 7:10 pm
https://youtu.be/q82H0kV4sxU
Nice video. Makes it look so Easy.

I have been scared out of doing wheel landing from other Maule owners telling me stories. But I know I should practice this more. Thanks again.
===========
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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by wtxdragger »

I like to wheel land, just need to make sure you're straight with the direction of landing.

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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by Mog »

I’m no pro, but I have operated my M4 in some extreme winds well exceeding demonstrated cross. All of those landings have been at half flaps in full three point. I always slow down as much as possible accounting for gusts and lulls. Always ends up being super short, but one or two certainly required a change of shorts. All very safe and ultimately controllable. My abilities at those times were vastly different than my experience when I first flew a Maule. At first I could keep it straight with a gentle steady headwind.

The only wheel landings I do come immediately after a stout 3-pt and heavy braking.

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Re: Aerodynamic Reason for 3-pt Crosswind Landing?

Post by andy »

There are good reasons to do wheel landings vs. three pointers. On a soft, rough or bumpy surface wheel landings allow the tail wheel and tail spring to take less of a beating. Forward visibility is much better in my airplane with 31" bush wheels in a wheel landing. Even on a paved surface that's a good thing but it's essential on a back country airstrip or any airstrip where a deer might wander out in front of you. For those who haven't had the experience, don't jam on the brakes while the tail is still in the air unless you are very familiar with the point at which a nose-over will occur. Maule tails are heavier than most taildraggers and once the tail is high enough and airspeed slow enough, elevator application will not prevent the nose-over.

I don't see much difference between tail-low wheel landings and three-pointers in a crosswind. The angle of attack for a three-pointer is higher than for a tail-low wheel landing but not that much. A level attitude wheel landing has little angle of attack so the wing produces less lift and is less susceptible to crosswind influence. The downside of a level attitude wheel landing is that it usually requires a faster final approach airspeed for a stabilized approach, which eats up more runway. I say "usually" because you can time the flare on a steep, slow approach to put the airplane in a level attitude just as the wheels touch down. It takes a fair amount of practice to do this. It's easy to bounce in a level attitude wheel landing so the pilot eases the airplane down to touch more gently, eating up a lot of runway in the process.
Andy
1986 MX7-180

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