The purpose of this page is to show the need for machine tools in the construction of the WAR Corsair landing gear. One of the reasons that you see few examples of our plane is that many of them are "taken out" by a landing gear failure. Our planes are durable and are usualy repairable after LG failure but some people lose heart. One reason that so few of these projects are completed is the difficulty with making metal parts.
It is my hope that these pictures will help builders see how simple it is to make their own gear properly. ( I am assuming that you are not familiar with machining metal)Go to main page "metal advice" for inexpensive solutions and suppliers. The original WAR produced landing gear is not as rigid as the gear shown in the plans (so I hear) so you are better off making your own.
You will need some basic measuring instruments and access to a mill and lathe. You could substitute the mill with a drill press which would mean hand reaming trunnion through holes.
A 0-6" dial caliper (not a plastic one!) should be considered the bare minimum. No matter what the claims are dial calipers are only accurate to +/- .001". The cheap ones may only be accurate to +/-.005" and user error may create this sort of inaccuracy even with a good instrument. The trunnion to upper leg tolerance is .01". (not much room for measuring error but it will work) I prefer to do rough machining measurements with the caliper then use micrometers for the finish cuts. A careful user of a dial caliper can acheive acceptable results for this sort of work though.
Before jumping in and making the chips fly write the tubing size on your unmarked pieces. Also note that I gave an extra .2" for the cut in the event that the tube is badly out of square.
Here is an aluminum mandrel that will help keep the tube centered. The ends of the mandrel are center drilled to mate with the tailstock live center. It is important to have the ends of your tube square so the bearing surface is even.
The trunnion tube gets one end squared at a time. There are several cuts but this only took about twenty minutes. A part of this time was spent forcing the aluminum mandrel out to switch sides and take measurements. This 9" Southbend lathe is almost as old as my grandfather and still does a fine job. If you consider buying a lathe, get a used one with tooling as opposed to something with a smaller swing than mine. You can spend two to three times the cost of your lathe on accesories and tooling.
A depth micrometer is the best way to get an accurate measurement. In between final cuts the depth mike was used. When the final .005" was left I lightly ran the ends of the tube over sand paper on a flat surface to remove burrs then took measurements and took a light cut. (A burr can add an extra thousandth or two.) I ended up with a 4.125" long tube.
At this point you may wonder, why does it need to be this precise? At the top of the trunnion are two bevel gears which cause the wheels to rotate during retraction. These gears need to mesh properly (the right angle and distance) to keep the tires pointed straight during landing. Most landing gear failures are caused by the axis of the tires turning sideways when adverse loads are applied. (Brakes at high speed, crab on touchdown etc...) Improper mesh of the gears is one cause of this and loose tolereances in the gear actuation assembly is the other. Ideally both of these areas should be as rigid as possible.
