flyrotary@lancaironline.net Mailing List Archive

Steve,

Tracy had a “no metal prop” exception for the rigid coupled drives. Was this due to weight or some other concern? My MT prop weights about 39#’s. I personally like the rubber dampers but I believe they should be considered a consumable item. Flat spots on the 45 durometer appear with less than 100 hours. May be as few as 50 hours. They are cheap but the minimum order is 600 units. I have a quote and plan to try and get a group buy together. If a group buy is possible I plan to buy 40 units and change every 50- 100 hours. A firmer material may last longer. Thinking about a 60 – 65 durometer. I’ll put the group buy information out to the group when I have time.

Bobby

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Tuesday, January 15, 2019 2:56 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Rubber Damper

Bobby,

When I was performing a dynamic balance of the turbo Renesis on the test stand with only the flex plate and damper plate installed, I was unable to achieve a solution due to the angular position of the heavy spot changing from one run to the next without attaching weights. Solid aluminum replacements for the dampers were made and installed. A dynamic balance solution was then achieved. It may be that the solid damper replacements would result in a setup very similar to the rigid coupling described as used in Tracy's latest drives. This was only done on the test stand and I have not installed the solid parts in the plane.

Steve Boese

On Jan 15, 2019, at 11:59 AM, Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:

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Tracy,

Service Rubber located the part number. It was actually a 45 durometer. They are providing a quote with minimum quantity.

Thanks,

Bobby

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Tuesday, January 15, 2019 12:29 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Rubber Damper

Tracy,

I’m exploring the possibility of have a batch of dampers made. Measuring the worn units is difficult. I found some information in the archives but need to confirm the measurements.

Supplier was Service Rubber in Texas. They have changed accounting systems and can’t located the part number. If you have the part number that would be most helpful.

OD 1.374”
ID 0.75”
Height --?

Durometer of 50. Looking at increasing to 65. Service Rubber recommended neoprene.

Depending on minimum quantity and price it will likely take a group buy. My 50 durometer develop flat spots very fast. I have been rotating them to move the flat spot to the opposite side. I think they need to be change every 50 – 100 hours. Harder material may survive longer.

Thanks,

Bobby