Wheel pant design isn't something to take lightly. They can and do affect the airflow on the plane.

A Cheetah converted to a 260hp IO540 (and previously owned by John Coze) was a new purchase for Geoff Bolton. John had installed these huge RV-10 style wheel pants. Turns out, flow separation from these wheel pants was causing the vibration.

Let's back up a bit:

2011: John Coze brought his plane to me for an annual and to get new elevator trim arms. Let me just say this, whoever put that elevator assembly together should be reported to the FAA. It was intensionally assembled wrong, using the wrong parts, to create as much drag on the control surface as possible.

After the annual and on the first flight, John complained to me of vibration in the horizontal. John apparently (disclaimer: I can only surmise this is what happened, based on the evidence) knew he had a vibration problem and had his mechanic take out all play.  After I removed all the illegal, improperly installed, parts in the elevator trim, it vibrated very badly. John took it back to his mechanic to 'fix' the problem.

2013: John Coze sold his plane to Geoff Bolton.  Geoff likes things done right.  I like customers like that.

2014: On it's first annual with Geoff as the new owner, I again, removed all the drag in the elevator.  The vibration returned. Geoff chose to live with it for the time being.

2015:  During this annual, we tried everything possibile to stop the vibration.  We added weight to the tail and tried several different rigging configurations of the elevator imaginal to stop the vibration.  No luck.  So, as a 'what if?', we removed the main gear wheel pants. The vibration went away. 

Who'd have guess.


I've seen a LOT of wheel pant designs.  The best place to look at wheel pant designs is the Reno Air Races. There are a lot of good and bad ideas there.  There are also a lot of very creative designs.

One of the biggest problems with a streamlined (main gear) wheel pants is hiding the brake caliper. When I thought about it, the wheel fairing is nothing more than a vertical airfoil.  I researched a LOT of airfoils and stumbled on the Davis airfoil. 

The Davis airfoil was used on the B-24.  For the speed range of the Grumman Tiger, this airfoil seems to fit pretty well.  The big plus is that the widest part (the thickest part of the cord) is about where the brake caliper fits. Hmm.

Of course, these will need a lot of flight testing.  But, I have a good feeling . . . .