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Metal Constant Speed Props

Props CSP Defiant

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#1 Scott Humphrey

Scott Humphrey

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  • Scott Humphrey
  • Savannah, Texas

Posted 23 September 2017 - 08:23 PM

Metal Constant Speed Props: 30 or 40 years ago Rutan may have warned people that a metal CSP will fail on the back of a canard. Confused air, strake interference blah, blah, yaddah, doom. Since then the community warns against metal CSP's specifically and CSP's in general. I think it's all hearsay and thought experiments without any evidence.
1. Is there any data developed by anyone in the community?
2. Has anyone ever had a metal CSP fail on a canard?
3. Is there anything at all other than hearsay and anecdotal evidence?
The Defiant I posted a few days ago has 2 blade metal CSP props on both ends. Takes off and climbs like a bat out of hell. Cruises at 175 kts TAS on 15gph. I think we were at 8500ft.
Keep the metal CSP's?
Put a Hoffman 3blade composite CSP on the back?
Cato fixed pitch on both ends?
Why change at all?
I love Rutan Designs but I think he is full of crap on the prop thing.Defiant.jpg



#2 TMann

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  • Thomas Mann
  • Omaha, NE

Posted 26 September 2017 - 09:30 PM

>2. Has anyone ever had a metal CSP fail on a canard?

‚ÄčNot that I know of. Most everyone took the advice and used a wood or composite prop.

 

>3. Is there anything at all other than hearsay and anecdotal evidence?

‚ÄčI usually follow the engineer's (Burt Rutan) report. With the technology and analysis tools available to us today, there is little reason to learn the same thing via experimentation.

 

When everyone is trying to discover ways to cut down on the empty weight of their airplane, why would you install a heavy prop (times 2.)


Edited by TMann, 26 September 2017 - 09:32 PM.

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