RE: Experienced with the TWM P-51 GS?
Since I’m new to gas and if anyone else that may want to try this may be also, I’m going to continue to document what I do in the gas engine process as well as the radio installation as those are the parts that are different than the smaller planes. Different engines will have different issues, but James Barr and I are having the same engine questions, so others will likely have them also.
James is much further on this project than I am. He is almost finished with his Miss America. He is dealing with getting the spinner on his. The spinner that comes with the [link=http://ecsvr.com/abm/shopexd.asp?id=18]P-51D Mustang G.S. Miss America[/link] is a plastic spinner with an aluminum backplate. It has a socket head screw that goes to an adapter nut. The nuts that come with the spinner are 5/16-24 and a size up. I’m not sure what size. The screw that goes into the nut is an M6 on my aluminum spinner. I’m not sure if James’ is an M5 or M6. The screw is only long enough to reach the adapter nut.
On the gas engines that use prop bolts, the prop shaft typically does not have threads on the shaft. The prop is bored to fit on the shaft and the bolts hold the prop to the prop hub. In one of my previous postings I showed a prop drill jig. The jig is so you can accurately drill the prop bolt holes.
One the MLD-35, the prop shaft has an M5 – 0.8 threaded hole in the end of it. So If an M5 would hold the spinner, theoretically I could use a long M5 socket head screw direct to the prop shaft. The screw would need to be 95mm to 100m long. Those screws can be found, but they aren’t stocked in many locations. Ironically a 10-32 will screw into a M5 threaded hole. It has just a little wiggle room. I found some 4” long 10-32 screws. But I don’t think that even Loctite would keep them from coming loose.
On the MLD-35, the prop shaft is simply an aluminum sleeve that is actually threaded M10 on one end and M5 on the other. I took it off a couple of weeks ago before I ordered the Pitts muffler and the drill jig. They were only a couple of bucks, so I ordered 3 of them. I went to Monroe Hardware on Saturday and found some screws. One I found was an M6 x 90mm. I could drill out the M5 end of the sleeve and tap it for M6. I would have about 1/4” of thread. As it turns out, that is all that is in the sleeve anyway. I did not find this out until I drilled out a sleeve for 5/16-24 and tapped it. I had found some 5/16-24 set screws to use as studs in lengths from 0.75” to 1.5”. So now I can use the spinner adapter nut. I could also use a Dubro Spinner Nut on the test stand as I plan to start the engine with a low speed hi-torque starter.
In a trip to Lowes I found .75” steel spacers and M5 x 1.5” screws. I have the S1 PSP Universal backplate Adapter. I had to drill new holes for the standoffs as this engine does not use a standard rectangular pattern. But I got the engine mounted on the backplate adapter. With the spacers I can test with the Pitts muffler. I will actually use the stock muffler for most of the break-in as I don’t want to stress the Pitts muffler. The Pitts muffler is a little crooked, but that shouldn’t affect the installation.