Wheel pants fitting

Webb · #1 07-02-2008, 09:21 AM

I've put this job off long enough. Here goes the prep work.

After reading threads on clearances, my understanding is there should be 3/4 to 1 inch clearance from tires for proper cooling. Makes good sense.

What I couldn't determine was how low other than a deflated tire should not allow the wheel pants to have contact with the deflated tire.

SO - if I used the bottom of the rim as the lowest point of the pants, would that be just about right?

pierre smith · #2 07-02-2008, 11:54 AM

....Webb,
Van recommends 1" from the top of the tire to the wheelpant. Duct tape a 1" piece of wood onto the top of the tire and you have your clearance. Just be sure that you have at least the thickness of your fingers (about1/2-5/8") clearance all the way around the tire since any side loads from weaving/taxiing will move the tire nearer the pant and it could pull them up into themselves and break one..ask me how I know

Regards,

Webb · #3 07-02-2008, 04:21 PM

I won't ask how you know. I'll just live vicariously through you.

Finger on the sides (3/4 to 1 inch) and an inch on top.

Again, thanks for the spacing.

Bob Axsom · #4 07-02-2008, 08:29 PM

I developed some sub fairings for my stock fairings that go down to between 3/4" and 1" from the ground and the gap around the tires is quite small. I published the weight on wheels and weight off wheels in the Forum earlier along with the dynamic observations. When on the ground the tire gap on the sides gets smaller and the fore and aft gaps get larger. The opposite is true in the air. There are no hard edge on interfaces between these subfairings and the tires. Side loads are a rub action on basically a flat side surface. The front interface has the tire rotating away from the edge so if there was any contact it would be a "going away rub" instead of a jam. The rear interface had to be handled carefully because the tire rotation is into it. I shaped the clay to turn that edge down to minimise the conflict and finished it smoothly with some extra fiberglass and a gap of around 1/4". The upward force on the tire upon ground contact increases that gap. I have had no problems at all with them. I intended these for racing only but based on my experience so far I am reluctant to take them off. This is just another experience for you and if you are not trying to squeeze out performance it is probably not very important to you.

Bob Axsom

Webb · #5 07-02-2008, 08:48 PM

OK - spill the beans. You didn't get those racing numbers all by themselves.

What's the improvement?

Bob Axsom · #6 07-02-2008, 09:31 PM

CORRECTION ON THE MLG SUBFAIRING EFFECT 7-3-08 (4:00PM CDT):

I got a lot from the subfairing in the old style flat sided nose wheel fairing - on the order of three knots (I made another change at the same time so that number is not pure). The ones on the MLG WHICH INVOLVE THE NEWER PRESSURE RECOVERY FAIRINGS ACTUALLY REDUCED THE TOP SPEED BY 0.5 KT. Removing the steps added 0.4 kt back and that was the number I reported for the MLG originally. Sorry for the error.

Bob Axsom