automan1223
Active Member
- Joined
- Nov 3, 2003
- Messages
- 3,760
- Location
- Oriental, North Carolina
- Aircraft
- 2p Tandem Air Command "Big Red"
- Total Flight Time
- 250
Prop hub
Prop hub
Somewhere on my computer I have a photo of a prop hub that separated the shaft that was driving it as it was in TWO PIECES. It would be great to see what "improvements" you guys made vis a la prop shaft / hub retaining system.
The clutch is a bad idea. EVERY CLUTCH I have ever worked with develops problems somewhere down the line.
If you really wanted to have a piece of engineering. Make the unit driven by a sprag setup. A one way roller sprag is the way to go. They are smooth at all power settings, cold, hot, high & low. Minimum moving parts, no clutch to wear out or come out of true to vibrate and go self destruct. Copying some elses design may be a place to start but not where it should end. That is piracy.....and it is not well received here.
Jonathan
Prop hub
Somewhere on my computer I have a photo of a prop hub that separated the shaft that was driving it as it was in TWO PIECES. It would be great to see what "improvements" you guys made vis a la prop shaft / hub retaining system.
The clutch is a bad idea. EVERY CLUTCH I have ever worked with develops problems somewhere down the line.
If you really wanted to have a piece of engineering. Make the unit driven by a sprag setup. A one way roller sprag is the way to go. They are smooth at all power settings, cold, hot, high & low. Minimum moving parts, no clutch to wear out or come out of true to vibrate and go self destruct. Copying some elses design may be a place to start but not where it should end. That is piracy.....and it is not well received here.
Jonathan
Not wanting to upset some of the belt driven and geared PSRU experts, I often wonder if they fully understand the requirements of a propeller reduction gearbox and the damaging effect that the torsional excitation produced by piston engines can have on gears, shafts and propellers. Subaru engines are not alone in this predicament; all engines have some degree natural frequency. A PSRU cannot be treated as an isolated entity.
In a moving mechanism, the dynamics of springs have to be analyzed too, valve springs in an engine have their own natural frequencies, and the core mechanic must ensure that springs are operated well under their first natural frequency at maximum engine speed, if not, risk damage to the pistons because the springs may not return the valves in time.
Our centrifugal operated pressure plate/clutch will not absorb and vibrations other than give back in this case the Subaru engines the proper balance and most important able to idle the engine without the propeller engaged. Starting a car in gear is not so health for the gearbox. We are working on a prop brake as with the centrifugal clutch there is a down site with the loss of glide distance after an engine out and we are stuck with a wind milling prop. The original reversed engineered box has been elongated to take the additional centrifugal clutch and after some Dyno testing and a flight implementations and to impress the buyer we have to accumulate at least 1000 hours and I guess at 2000 hours they will be sold.
To avoid confusions, the posted pictures, have the centrifugal clutch omitted (obvious reasons) but it gives some indication on our R&D. Hopefully we would be able to market the centrifugal clutch not only for Subaru engines.
Thanks
Albert