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On Blended airfoil prop

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mppalmer(at)aol.com
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Posted: Wed Feb 10, 2010 5:02 am Post subject: On Blended airfoil prop

Wow, a 20 mph gain is impressive! Seems like Hartzell has got it 

figured out. (Too bad they don't make such a prop for the lowly O-320.)



In addition to a quieter ride, I bet your engine cooling is better too. 

You might be able to close down the inlets later and get a few more 

knots. (Whereas, with our Hartzell prop, with its big, round roots, I 

never noticed a difference  in speed by reducing the inlets. I suspect 

the drag from the prop roots is the bigger factor, per Paul Lipps.)



Now, if only Glasair would re-loft the airframe on a PC and tweak the 

fiberglass to reduce drag...



 	  Quote: 	
		  My indicated airspeed using my old  Hartzell averaged around 163 mph 

at those settings
	


 	  Quote: 	
		  at those altitudes.  Using my new blended foil design, I noted 

indicated airspeed of 185 mph.
	




Mike Palmer <><

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Craymondw(at)aol.com
Guest

Posted: Wed Feb 10, 2010 10:13 am Post subject: On Blended airfoil prop

Mike Palmer,

       Don't jump the gun yet, this was only  my first flight with our new blended foil prop and the Sky Gods may  have had the atmosphere in perfect order. Depending on atmospheric  conditions we have recorded a wide range of cruising speeds in the  past.  It will take several flights in different atmospheric  conditions to verify if the prop added a full 20 mph to my  cruise.  My gut tells me it has. As far as cooling, I closed up  the cowling inlets several years ago. And contrary to what one would surmise  with this new prop,  our engine didn't run cooler but instead ran a little  hotter. The only two things I can surmise is that the engine is actually  working and pulling harder with the blended foil or because of the faster speed  the tail is up higher disturbing the air in  the inlets. When Deborah competed in the 1994 Sun and Fun Race  she averaged around 220 mph with all knobs full forward. But at altitude we  found we get our best speeds around 2400 rpm. I think in the thinner air our old  prop just created prop turbulence at higher RPM's.  Before I  added the blended foil prop I took Ken Johnson's advice and closed up  our cowl side mounted injector inlet by almost three inches and our cooling  inlets by an inch. Note: If you do that, remember to bring the lower section  forward or you create an air dam! Dropping plumb lines off the fuse center line  and drawing parallel caulk lines on her hanger floor and realigning the wheel  pants gave us a big jump in speed. Our next big increase was removing the 2  degree droop out of her flaps and filing a notch in the fairing so we  could slightly reflex the flaps. That gave us another jump in  cruise speed.  After a nose wheel failure in 1996, I disassembled the  plane and put it on a diet and removed well over 100 pounds. The first paint was  a heavy Centuri over a heavy lacquer primer. I shaved and sanded  everything off and placed the debris into plastic garbage bags and weighed them.  They came out to 45 pounds!!  After that I sanded the jell coat almost  to the fiber glass and primed it with a light weight epoxy primer and  finished it off with an ultra light Pittsburgh, base coat, pearl coat and  top coat system. I placed in a light weight starter, a set of lighter Slick mags  and a light weight battery and light weight upholstery. 

    Before I built Deborah's Glasair, she owned a T-18 that  cruised around 170 mph on a tricked out 320 Lyc. The first flights on  Deborah's Glasair only produced a cruise speed of around 190 mph and we wanted  to strangle Ted Setzer when he advertised 225 mph to 235 mph cruise speeds. It  took a lot of tweaking over the years to get up to 205/210 mph cruise speed  she now has on her Glasair. Even with that, we always felt the Glasair was far  capable of greater speeds because on long descents from altitude we would  commonly see 225 to 235 speeds and felt it was the prop. This was verified  when we met up with a Glasar 2 FT driver that opted out of a Hartzell  for a McCauley prop having cruise speeds over 220 mph.  

  

                                                          Charles Raymond   message dated 2/10/2010 8:02:32 A.M. Eastern  Standard Time, mppalmer(at)aol.com writes:

   	  Quote: 	
		  -->    Glasair-List message posted by: mppalmer(at)aol.com



Wow, a 20 mph gain is    impressive! Seems like Hartzell has got it 

figured out. (Too bad they    don't make such a prop for the lowly O-320.)



In addition to a quieter    ride, I bet your engine cooling is better too. 

You might be able to close    down the inlets later and get a few more 

knots. (Whereas, with our    Hartzell prop, with its big, round roots, I 

never noticed a    difference  in speed by reducing the inlets. I suspect 

the drag from    the prop roots is the bigger factor, per Paul Lipps.)



Now, if only    Glasair would re-loft the airframe on a PC and tweak the 

fiberglass to    reduce drag...



 	  Quote: 	
		  My indicated airspeed using my old  Hartzell    averaged around 163 mph 

at those settings
	


 	  Quote: 	
		  at those altitudes.     Using my new blended foil design, I noted 

indicated airspeed of 185    mph.
	




Mike Palmer  =========================   e the  ties  Day  ================================================               - MATRONICS WEB FORUMS  ================================================             - List Contribution Web Site  sp;                             ===================================================



	


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