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540 power settings

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LessDragProd(at)aol.com
Guest

Posted: Thu Apr 20, 2006 8:55 am Post subject: 540 power settings

Just some general information on three different 540 power  settings.

  

 This information was obtained in an unfinished (unpainted and some fairings  missing) RV-10 with a 3 blade MT Propeller.

 The data was taken at 8,000' density altitude, at full throttle  (around 23' MP) and leaned consistently:

  

 2500 RPM 20 gph (Van's standard cruise performance power setting)

 2300 RPM 15 gph - airspeed was 1 knot faster than at the 2500 RPM  setting.

 2100 RPM 12 gph - airspeed was 6 knots slower than at the 2500 RPM  setting.

  

 Making the following assumptions:  60 gallons of fuel usable less  a 1/2 hour reserve, and using Van's Aircraft RV-10 cruise performance of about  200 mph.

  

 At 2500 RPM, there is 2 1/2 hours of fuel available for a range of 500  miles.

 At 2300 RPM, there is 3 1/2 hours of fuel available for a range of just  over 700 miles.

 At 2100 RPM, there is 4 1/2 hours of fuel available for a range of  almost 870 miles.

  

 Or . . . 

  

 At 2100 RPM, after flying for 2 1/2 hours and covering 480 plus miles, you  would still have about half of your fuel remaining.

  

 According to MT Propeller (for a "natural composite" MT Propeller);  running a Lycoming 200 RPM below the manifold pressure is acceptable.

 The 2100 RPM 23" MP power setting would be an acceptable cruise power  setting with a "natural composite" MT Propeller.

 A commonly accepted lowest RPM power setting for an aluminum blade  propeller would be 2300 RPM at 23" MP.  (For anyone that is interested, MT  Propeller does manufacture aluminum blade propellers.)

  

 Regards,

 Jim Ayers

 PS A reduction in airspeed with a higher RPM is expected.  As an  approximation, the RPM increase is linear, but the horsepower increase  requirement is at a power of 2.

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johnwcox(at)pacificnw.com
Guest

Posted: Thu Apr 20, 2006 6:25 pm Post subject: 540 power settings

Jim, its great to have hard numbers.  

   

John - KUAO  

         

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of LessDragProd(at)aol.com

 Sent: Wednesday, April 19, 2006 8:10 AM

 To: rv10-list(at)matronics.com

 Subject: 540 power settings  

  

     

Just some general information on three different 540 power settings.  

    

   

    

This information was obtained in an unfinished (unpainted and some fairings missing) RV-10 with a 3 blade MT Propeller.  

    

The data was taken at 8,000' density altitude, at full throttle (around 23' MP) and leaned consistently:  

    

   

    

2500 RPM 20 gph (Van's standard cruise performance power setting)  

    

2300 RPM 15 gph - airspeed was 1 knot faster than at the 2500 RPM setting.  

    

2100 RPM 12 gph - airspeed was 6 knots slower than at the 2500 RPM setting.  

    

   

    

Making the following assumptions:  60 gallons of fuel usable less a 1/2 hour reserve, and using Van's Aircraft RV-10 cruise performance of about 200 mph.  

    

   

    

At 2500 RPM, there is 2 1/2 hours of fuel available for a range of 500 miles.  

    

At 2300 RPM, there is 3 1/2 hours of fuel available for a range of just over 700 miles.  

    

At 2100 RPM, there is 4 1/2 hours of fuel available for a range of almost 870 miles.  

    

   

    

Or . . .   

    

   

    

At 2100 RPM, after flying for 2 1/2 hours and covering 480 plus miles, you would still have about half of your fuel remaining.  

    

   

    

According to MT Propeller (for a "natural composite" MT Propeller); running a Lycoming 200 RPM below the manifold pressure is acceptable.  

    

The 2100 RPM 23" MP power setting would be an acceptable cruise power setting with a "natural composite" MT Propeller.  

    

A commonly accepted lowest RPM power setting for an aluminum blade propeller would be 2300 RPM at 23" MP.  (For anyone that is interested, MT Propeller does manufacture aluminum blade propellers.)  

    

   

    

Regards,  

    

Jim Ayers  

    

PS A reduction in airspeed with a higher RPM is expected.  As an approximation, the RPM increase is linear, but the horsepower increase requirement is at a power of 2.

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Dick Sipp

Joined: 11 Jan 2006
Posts: 215
Location: Hope, MI

Posted: Thu Apr 20, 2006 7:20 pm Post subject: 540 power settings

Jim:

  

 Are the RPM limits you refer to in the second half of your  message MT limits for their propellers?

  

 The Lycoming IO-540-D series charts from the engine  operators manual provide much broader RPM vs. manifold pressure  limits.

  

 Above 5500' there is no manifold pressure limitation for any  RPM.  Below 5500' manifold pressure limits are shown; as an  example,

 at 1800 RPM 24 inches of manifold pressure is the  limitation.  At  sea level and 2200 RPM the manifold pressure limit is  28.5", above 2200 RPM there is no manifold pressure limit.

  

 These charts show that the old wives tale of not operating  "oversquare" is mostly legend and not a problem as far as Lycoming is  concerned.

 While I am not suggesting that operating continuously at a  limitation is prudent, very efficient operation does occur at full throttle  settings and relatively low RPMs.  An added benefit is smoother and quieter  operation as well.

  

 It would be a shame if MT placed more restrictive limits on  engine operation than does the engine manufacturer.

  

 Dick Sipp

 40065

  

  	  Quote: 	
		           

According to MT    Propeller (for a "natural composite" MT Propeller); running a    Lycoming 200 RPM below the manifold pressure is    acceptable.

      

The 2100    RPM 23" MP power setting would be an acceptable cruise power setting with    a "natural composite" MT Propeller.

      

A commonly    accepted lowest RPM power setting for an aluminum blade propeller would    be 2300 RPM at 23" MP.  (For anyone that is interested, MT Propeller does    manufacture aluminum blade propellers.)

      

 

      

Regards,

      

Jim    Ayers

      

PS A    reduction in airspeed with a higher RPM is expected.  As an    approximation, the RPM increase is linear, but the horsepower increase    requirement is at a power of  2.

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LessDragProd(at)aol.com
Guest

Posted: Fri Apr 28, 2006 7:30 am Post subject: 540 power settings

Hi All,

 I received the following answer from MT Propeller engineering regarding the  question Dick Sipp asked.

  

 "Hi Jim,



As I told you yesterday on the telephone our propeller has  no limitations in respect to rpm and MAP settings, like 28 inch and 2200 rpm.  This problem is only with aluminum propellers.



So, we have no limitations  of our propeller operation except the engine limitations from the engine  manufacture still apply.



With best regards,

MT - Propeller Entwicklung  GmbH

Martin Albrecht

Engineering"



 So I hope this answers your question, Dick.

 The engine is the limiting factor with the 3 blade MT Propeller.

 For continuous operation; 1800 RPM at 25" mp to 2200 RPM at 29" mp.

  

 Whereas the aluminum blade propeller is the limiting factor on the  Lycoming engine.

  

 And you're right.  It is a shame if the propeller manufacturer  "placed more restrictive limits on engine operation than does the engine  manufacturer."  Unfortunately, it appears to be a Hartzell problem.

  

 Regards,

 Jim Ayers

  

 In a message dated 04/20/2006 8:21:24 PM Pacific Daylight Time,  rsipp(at)earthlink.net writes:

  	  Quote: 	
		     Jim:

    

   Are the RPM limits you refer to in the second half of your    message MT limits for their propellers?

    

   The Lycoming IO-540-D series charts from the engine    operators manual provide much broader RPM vs. manifold pressure    limits.

    

   Above 5500' there is no manifold pressure limitation for any    RPM.  Below 5500' manifold pressure limits are shown; as an    example,

   at 1800 RPM 24 inches of manifold pressure is the    limitation.  At  sea level and 2200 RPM the manifold pressure limit    is 28.5", above 2200 RPM there is no manifold pressure limit.

    

   These charts show that the old wives tale of not operating    "oversquare" is mostly legend and not a problem as far as Lycoming is    concerned.

   While I am not suggesting that operating continuously at a    limitation is prudent, very efficient operation does occur at full throttle    settings and relatively low RPMs.  An added benefit is smoother and    quieter operation as well.

    

   It would be a shame if MT placed more restrictive limits on    engine operation than does the engine manufacturer.

    

   Dick Sipp

   40065

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