Wheelpant Gap Seals

[DanH]

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Molded some urethane and glass to make wheelpant gap seals for my new pants, which are mounted much higher over 380-150's.

These seals match the exterior profile of the pants, the idea being to be symmetrical top and bottom. The tire cutout shown here is preliminary, and will be trimmed more upon installation.
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[DanH]

Dan, is this expanding your soft field usablility? I hope you will tell us the speed effect too with (I assume) more wheel showing below.

I did not know the wheel pants were symmetrical (!!), forming the flex upside down is clever!! It will help those with lower wheel pant damage and need of reconstruction too.

Yep, and my original wheelpants, mounted very low over 500-5's, would not fit over the larger tire. They only had 3/4" ground clearance behind the tire with the tailwheel on the ground, with rubber bottoms all the way back to the tail for impact flex. These new pants are conventional, with several inches of ground clearance, thus simple gap seals.

Trimmed and fitted last night, cruise speed test today. They're cut tight enough that some areas will need to wear into place.

In retrospect, I should have trimmed the wheelpant to have a lot more gap, for less chance of damage if I have a flat. The seals were molded with three plies of 9 oz plain weave and Shore A 80 urethane (PMC 780), and they turned out more than stiff enough to span a gap 1" or more.
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[jibby212]

I just repaired my wheel pant that were damaged due to not enough clearance between the wheel and pant. I was considering something like you have done. How much PMC 780 is required? I see they offer a 3lb trial kit, I would think this should be enough?

 

[DanH]

I just repaired my wheel pant that were damaged due to not enough clearance between the wheel and pant. I was considering something like you have done. How much PMC 780 is required? I see they offer a 3lb trial kit, I would think this should be enough?

More than enough, but it's fun stuff to have around.

Get some tint agent too.

I think I mixed a 150 gram batch for each.

 

[hgerhardt]

One would think that brake overheating might be an issue with the tires fully sealed like that, but apparently not as you've found from your previous experience?

 

[DanH]

One would think that brake overheating might be an issue with the tires fully sealed like that, but apparently not as you've found from your previous experience?

Good comment. With the previous sealed pants I made it a point to be conscious of brake temperature. It had the standard thin disks, so very little margin even when well vented.

Here I left a cutout at the caliper. Would have needed a bump to clear it anyway. And this time I mounted thicker disks for more kinetic energy capacity.

 

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Yep, and my original wheelpants, mounted very low over 500-5's, would not fit over the larger tire. They only had 3/4" ground clearance behind the tire with the tailwheel on the ground, with rubber bottoms all the way back to the tail for impact flex. These new pants are conventional, with several inches of ground clearance, thus simple gap seals.

Trimmed and fitted last night, cruise speed test today. They're cut tight enough that some areas will need to wear into place.

In retrospect, I should have trimmed the wheelpant to have a lot more gap, for less chance of damage if I have a flat. The seals were molded with three plies of 9 oz plain weave and Shore A 80 urethane (PMC 780), and they turned out more than stiff enough to span a gap 1" or more.
.

Dan have you done any measurements before and after? do you gain any airspeed?

 

[DanH]

Dan have you done any measurements before and after? do you gain any airspeed?

This is more about not losing any speed, as compared to the previous low-mounted pants over small tires.

 

[flyboykelly]

I added this exit vent to assist in cooling along with the air inlets. They seem to work well with keeping the brakes cool.

 

[DanH]

I added this exit vent to assist in cooling along with the air inlets. They seem to work well with keeping the brakes cool.

Brian, internal wheelpant flow is the same as powerplant cooling flow. If the exit velocity is lower than freestream, mass flow x loss of velocity = drag.

 

[flyboykelly]

Brian, internal wheelpant flow is the same as powerplant cooling flow. If the exit velocity is lower than freestream, mass flow x loss of velocity = drag.

I didn't see any speed loss with this mod.

 

[planenutz]

I think those outlets would be an outstanding location for one of Flyboykelly's mates to hide a whistle or Harmonica as a practical joke. Certainly if he lived on my airfield he'd be whistling his way across the sky.

 

[DanH]

I didn't see any speed loss with this mod.

I am curious. Why that much brake cooling? As noted, I flew 1150 hours with thin disks and fully sealed pants.

 

[flyboykelly]

I am curious. Why that much brake cooling? As noted, I flew 1150 hours with thin disks and fully sealed pants.

I had a brake fire a while back.