Wheel Pant Alignment and Cutout

[6896]

Yes, I believe that to be the case. If I picked out the other cylinder, the bleeder screw would be on top. I took care of this over the weekend, even though the posted photos don't show the change in bleeder screw position.

[6896]

Meant to say, bleeder screw on the bottom.

[6643]

Plate has the bottom three holes in line

Am I confused? Were the holes for the axle bolts and the brake caliper already there? It seems to me that the backing plate only fits one way on the pant, and the axle holes and brake cutout should be what changes for the swept gear.

I have a set of badly beaten (barely recognizable) original backing plates I can photograph if that would help.

[6896]

Sure, I'll take any photos or measurements to assist.

My objective, which I think is correct, is to make the gear leg perpendicular to the streamline axis of the wheel pant while in level flight. Since the pant is not drilled yet for the backing plate, the plate can be positioned in any number of positions on the pant, but the correct position ensures all of the nutplates fall somewhere on the uncut portion of the pant and the gear leg is perpendicular to the pant horizontal streamline. I am assuming the horizontal rib line on the pant is the streamline reference in level flight that the straight gear leg should be perpendicular to. The swept forward gear would not necessarily have to be perpendicular to the wheel pant horizontal rib, even though the pant horizontal rib would still need to be positioned parallel to the streamline in level flight.

My issue is that if I follow the hole pattern on the backing plates for the 10-32 screw nutplates in the photos that were sent to me, and transfer those holes to my pants and position the plate over the holes (just marks for now), the horizontal centerline through the four axle holes with respect to the rib line on the pant are not parallel, which means the gear leg would not be perpendicular to the horizontal rib of the pant. You can see that in my photo, which would put the pant into a nose low position. From the photo of the pant with the cutout and drilled holes, you can see that the lower holes near the bottom of the pant are all on the same line, which fixes the position of the pant. If I follow this layout, the plate tips backward.

So, I have to move the position of the lower, forward (leading edge) nutplate up so I can rotate the front of the plate down a bit relative to the pant. The balancing act is to ensure the upper nutplates have clearance from the horizontal pant rib so the head of the machine screw is flat on the pant and the lower nutplates are still on the pant.

[6896]

Here is a diagram that attempts to explain what I am seeing. The lower, forward nutplate seems to be positioned too low, which prevents me from getting the straight gear leg perpendicular to the the wheel pant horizontal rib line. If the nut plate where raised say 5/8 in, then the plate could be rotated forward a bit to square up the gear leg with the horizontal pant rib line. The centerline of the straight gear leg should be perpendicular to the horizontal rib line of the wheel pant.

[6643]

y objective, which I think is correct, is to make the gear leg perpendicular to the streamline axis of the wheel pant while in level flight.

I think that will work, although I think the actual goal is to have the streamline axis parallel to the direction of flight.

My recollection is that the bottom of the plate aligns with the bottom of the wheel pant, which is why I said it only fits one way.

I'll try to find the plates. I think they are here whereas the pants are at the airport, so I can't show both...

[6643]

Damned engineers! Have to overthink everything! (JK!)

I believe the plate should be rotated clockwise until the flat section on the bottom aligns with the bottom of the pant. The holes for the axle should be on a line approximately perpendicular to the streamline axis of the pant, and the brake cutout then CCW from where it is now.

[6896]

Here's another photo that superimposes the photo of the pant mounting plate onto the photo of a pant sent to me with the holes for the mounting plate pre-drilled. This shows the issue of the centerline of the gear spring not being perpendicular to the pant horizontal rib line, which is the closest reference I have for aligning the pants to be parallel to the direction of flight. I still think the forward nutplate needs to be relocated up a bit so the forward end of the plate can be tipped down a bit to get the perpendicular orientation of the gear let to the pant horizontal rib.

I'll reach out to Matt Lahti again.

Thanks.

[6896]

I think I answered my own question. I was making an assumption about how the gear leg exits the gear box in the fuselage. Examining the three view and drawing a few lines convinced me that the mounting plates lower holes should be parallel to the bottom of the pants because even the straight gear leg sweeps forward a bit because the gear box line is not exactly parallel to the line of flight. This is where I assumed wrong.

I'll do the final fit up of the pant with the gear leg installed on the fuselage rather than a bench in the workshop to see the complete picture.

See attached side view drawing.

Thanks.

[6643]

That drawing sure looks like swept gear to me. On early planes the center of the axle is 3" behind the leading edge when the plane is leveled. That one looks even with the leading edge.

Were the holes for the axle bolts already in the backing plates when you got them?