Mailing List flyrotary@lancaironline.net Message #720
From: Mike Wills <willsm@spawar.navy.mil>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: [FlyRotary] Engine Mounts
Date: Thu, 19 Dec 2002 19:37:26 -0500
To: <flyrotary>
Scott,

 The sandwich plate between the engine and oil pan was pioneered by Tracy Crook. Its a good approach and the only potential pitfall I see is that it could end up adding a little unnecessary weight. If Conversion Concepts was around when I was ready for a mount I probably would have just bought his mount.
 The mount that ties into the PSRU mounting plate as produced by Jerry Hey is advocated by Paul Lamar. I see two problems. First is that I believe Tracy recommends against this due to the possible loads that could be applied to the PSRU. I think this mounting scheme voids Tracy's warranty on his PSRU. The second issue is that this scheme could cause problems with fitting an exhaust system. Probably not a problem for a wide airplane but on a skinny plane like my RV4 there would be problems with motor mount tubes blocking the exhaust ports of the engine.
 I made brackets that attach to the engine center housing same as the engine is mounted in the car. My lower motor mount tubes attach to these points. I then made a couple of aluminum brackets that attach to the water pump housing and the accessory mount on the plugs side of the engine. My upper mount tubes attach to these. If I recall correctly, my mount including brackets weighed about 14.5 pounds. This includes the main landing gear mount. The stock conical mount from Vans was about 11 pounds I think.
 I think the ultimate choice would be a mount that allows the engine to be cantilevered, just like a typical aircraft engine. This would provide the most flexibility for mounting accessories. But I couldnt figure out a good clean way to do it. Ken Powell has a mount like this.

 On the intake manifold I'll go with what the others said. Aluminum for its ability to deal with the heat.

 On the exhaust I'm using 321 stainless. Expensive but I'm hoping that will be offset by the fact that I wont have to continually repair it. I'm using .065 wall tubing for durability. The muffler I'm building is Inconel.
 On the subject of tuning, most racers say that the rotary is very responsive to a tuned header. You have to offset this against weight and space considerations for your application. I'm going with an equal length header with primaries about 24" long because thats what fits in the space I have available.
 If you dont care about the tuning, have the $, have the space, and want to go light and durable, I understand that Dave Atkins can provide a complete Inconel exhaust/muffler. If done right it should last forever.

Mike Wills

At 10:17 PM 12/18/2002 -0500, you wrote:

Posted for Scott <squiggles@yahoo.com>:

Hello All...

Is there a major benefit to taking one mounting
approach over another?

Thanx...

-Scott

Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster