Engine Mount Tubes

[Rich Snyder]

I have been looking over the nice cross sectional view of the motor mount tube provided by Mike Pastor. It all looks good to me except that the tube itself is only about half the thickness of the tube that Leonard specifies in the plan. (.065" vs .125"). I see the 1 1/8" x .065 in the AS&S catalog but there is no .125"wall. Does this have to be 4130? What are the expected forces on this short piece of steel tube? Once the rubber bushing is in place, the steel tube will only be transferring the load from the rubber bushings and nylon or aluminum insert, to the engine mount. Does anyone think that the thinner wall tubing will distort? Lastly, will plain old black iron gas pipe weld OK to 4130? Haven't tried that myself. Rich.

[Steve]

I have been looking over the nice cross sectional view of the motor mount tube provided by Mike Pastor. It all looks good to me except that the tube itself is only about half the thickness of the tube that Leonard specifies in the plan. (.065" vs .125"). I see the 1 1/8" x .065 in the AS&S catalog but there is no .125"wall. Does this have to be 4130? What are the expected forces on this short piece of steel tube? Once the rubber bushing is in place, the steel tube will only be transferring the load from the rubber bushings and nylon or aluminum insert, to the engine mount. Does anyone think that the thinner wall tubing will distort? Lastly, will plain old black iron gas pipe weld OK to 4130? Haven't tried that myself. Rich.

I know made his LE tubes to his drawing dimensions but in fact he made his engine mount to hard fasten into the 1/2 Vw bushing tube and did rubber donuts out at the UV case attaches... You need 40-50 hardness rubber bushings on the UV mount - not shock absorber bushings which are too hard and don't insulate the motor from the airframe...

The XL tube is available at Spruce in .120 wall here: http://www.aircraftspruce.com/catalog/mepages/4130tubing_un1.php

[Rich Snyder]

I know made his LE tubes to his drawing dimensions but in fact he made his engine mount to hard fasten into the 1/2 Vw bushing tube and did rubber donuts out at the UV case attaches... You need 40-50 hardness rubber bushings on the UV mount - not shock absorber bushings which are too hard and don't insulate the motor from the airframe...

Thanks Steve. Help me with the abbreviation though. UV?? I'm thinkin' Ultravair? Universal? Sorry...Dumb rookie.  I think I will order the 4130 tubing,(Pipe), as per Leonard's XL plans. And thanks for the 4130 tube page! Rich.

[Steve]

Thanks Steve. Help me with the abbreviation though. UV?? I'm thinkin' Ultravair?

 In Eagler lingo UV = Ultravair . . .

[Rich Snyder]

Great! Made a good guess.;D Rich.