Wednesday, October 25, 2017

FJ-2/3 Nose Landing Gear

Warning: Probably more than you want to know!

First an overview of the nose landing gear from the side.
Note that the shock strut is angled slightly forward and the yoke is mounted in front side of it. The anti-torque scissors on the right side of the strut is angled somewhat aft. The Sword assembly illustration would have you mount the yoke on the bottom of the strut and have the scissors angle forward. Paul Boyer also noted that it would have you put the shimmy damper and the anti-torque scissors on the wrong sides.

This is a closeup of the interface between the strut and the yoke;
Craig Kaston photo

Note that there is a shimmy damper mounted on the left side of cylinder that the yoke is mounted under. It turns out that the yoke is free to rotate within that cylinder since it is basically a sleeve ( there is no nose-gear steering; the pilot steered during taxi and the first part of takeoff and the last part of landing with the brakes).
The shimmy damper does not turn with the nose wheel; it is connected to the yoke where it protrudes at the top of cylinder. What confused me at first looking at pictures of FJs in museums was that lever extending aft on the left side of the yoke. At first I assumed that the museum had left something off but I finally realized that the shiny cylinder at the end of that lever contacted some kind of "ramp" in the nose-wheel well as it was going into the well that turned the wheel 90 degrees so it lay flat under the inlet duct. (On the F-86 that was done with an actuator.) Presumably the shimmy damper provides a centering function when the landing gear is extended.

The line coming down from the wheel well to the bottom of the shock strut pressurizes it to raise the nose for a catapult takeoff. However, the actual routing, at least early on, is along the scissors as shown on this early production (a few were blue) FJ-2:

Here is a comparison of the "normal" strut extension and pressurized for a catapult launch:
However, the strut might be somewhat or fully extended at other times for various reasons.

The Sword nose landing gear strut appears to be too long. I assembled the three big pieces. I drilled an .080 hole in the cylinder in front of the strut and in the yoke to pin them together with a piece of wire since I think simply gluing them won't be sturdy enough.
It looks like I'll need to cut off that thicker section at the top of the strut and "flatten" the tire a bit to get closer to the right "sit". The yoke is also too long but shortening it looks like to much work.

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