Text Box: WARBIRD NOTES #40    9 Jun 2000  (6)    
TRIM DURING A CROSSWIND LANDING
I’ve really hesitated to believe that this elementary matter merited discussion – and if it did – perhaps somewhere at the student pilot level!  However, a few events and/or incidents that have occurred lately demonstrated rather clearly that it does!  Let me briefly <very big grin> describe these events to you, and see what you might think about it!

 

Consider the first one.  This was in a four-engine WWII bomber with a tailwheel.  We were approaching a hard surfaced runway for a landing to the west.  Wind was from the south (left) – brisk – but well within the limitations.  In this case, the pilot-in-command was sitting in the right seat (due to a requirement existing at that time concerning giving rides, not germane to this story).  At any rate, about a mile or so out on final, I observed that he began to lower the left wing into the wind, and at the same time, it seemed to me that he began to oppose this bank with an appropriate amount of right rudder.  So far – so good, right?  Using this technique while still w-a-y out on final seemed like a lot of work to me.  But then I thought about it a little bit more.

 

I reminded myself of the fact that we used to teach this technique to beginning students new to the B-25 back in the USAF multi-engine flying training program.   Simply because the new student was not yet exactly sure of where straight ahead was in a new – to him – side-by-side airplane!  So, I kept the thought in mind that we’d utilized this exaggerated maneuver in order to give the student plenty of time for him to get the sight picture of what straight ahead looked like!  And also to allow him to experience the constantly changing effects of a crosswind and appropriate control usage to deal with it.  But I’ll guarantee you we never expected him to continue this exaggerated technique into his future flying assignments as a military pilot.  It was just an interim thing, a training aid to help him get the sight picture.

 

Now – back to the crosswind landing in the B-17.  Very shortly after he applied the cross-controls, I looked down and noticed that my rudder pedals were NOT where I expected them to be.  They seemed to be roughly equalized, not in the unequal position one would expect under these conditions.  My first thought was “Shoot, I’ve somehow forgotten to set them correctly on the pre-flight before departure”.  First time for everything, I remember thinking.  Then – I looked at the throttles!  They were widely split, the left side engines had in the area of 5 to 8 inches more manifold pressure than the ones on the right side.  I can remember next glancing over my shoulder at the jumpseat rider (who just happened to be a FAA inspector) to see what his impression might be of this.  His only reaction was to roll his eyes upward towards the sky or the roof overhead as if to say, “I haven’t the slightest idea what he’s doing either!”  So, I guess we’ll just ride this horse to the end, be interesting to see what happens! 

 

A short while later, we neared the touchdown.  He landed in this condition, pretty well on the centerline, touchdown was OK.  For a little while, I thought that it was all going to work out just fine.  Then, we began a slow – apparently inexorable – digression towards the right side.  Shortly, a departure from the pavement was imminent.  This runway has runway lights, approximately two or three feet high, installed a few feet off to the side of the pavement.  At this point, I grabbed the controls and took over, not wishing to explain to any observers the destruction of several runway lights by an airplane in which I was seated up front.  Lifted the right wing w-a-y up to clear those lights and – with power added – re-established the airplane on the center of the runway and got it stopped. 

 

Now, we finally get to the point of this illustration or story!  When I regained my breath and asked what in the world he had been trying to do, he proffered this comment, ”I didn’t have any access to the aileron trim!”  Now, I’m totally sure that most of you reading this might have an incredulous, or questioning, expression on your face just now, as I also did back then!  What in the world does aileron trim have to do with a crosswind landing, you might ask?  Others however (I suspect) might have it lurking – malevolently – somewhere in their flight training or previous experience backgrounds!        

R. Sohn   © 1999

 

Yet to write:

 

Bearcat

 

Elevaotr

 

Plaster a load of 400 paying passengers against a airplane’s cabin sidewall and just imagine the letters you’d get from them and the system chief pilot.

 

Go around, either torque/P-factor or loss of one or two engines.

 

Reduced control effectiveness

 

Loss of “feel”

 

Short term trim to relieve the control loads, constant change of x winds on final ,  gusts, etc.

 

 


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