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                           TeamGrumman-List Digest Archive
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                     Total Messages Posted Sun 03/27/05: 1
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Today's Message Index:
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     1. 08:16 AM - (no subject)  (LesDrag@AOL.COM)
 
 
 
________________________________  Message 1  _____________________________________


Time: 08:16:45 AM PST US
From: LesDrag@AOL.COM
Subject: TeamGrumman-List: (no subject)

--> TeamGrumman-List message posted by: LesDrag@aol.com


Hi All,

IMHO, Andy has it right.

On the "Lycoming 360 propeller" page of my website, _www.lessdrag.com_ 
(http://www.lessdrag.com/) , I have the data taken on  four different CS propellers 
in an RV-6A with a Lycoming O-360 180 hp  engine.  When you look at the 
airspeed with RPM for all four CS propellers,  there is NO speed increase in cruise

at full throttle above 2500 RPM.   In fact, there is usually a speed decrease 
at 2700 RPM.  On all 4  propellers.

What is significant is the reduction in fuel flow at 2300 RPM and full  
throttle with little loss in cruise speed.  In fact, the 3 blade MT  Propeller

exhibited a basically flat airspeed at 12,500' with full throttle from  2700 RPM

to 2300 RPM.  Only the fuel flow changed.

BTW, Someone previously mentioned the "old" airfoil used on the MT  Propeller 
for the Tiger.  This -17 blade actually consists of a smooth  transition 
through five airfoils from blade root to  blade tip.
It's nice that Hartzell is using this "old" technology  with their new 
"blended airfoil" propeller.  :-)

Regards,
Jim Ayers
Less Drag Products, Inc. - An MT Propeller distributor
(805) 795-5377
PS The other problem mentioned.  Cost.  I can help  to reduce the expense.

In a message dated 03/26/2005 7:53:44 PM Pacific Standard Time,  
loanshark@msn.com writes:

Increasing the RPM restriction would defeat the purpose of the prop.  The 
power translates to more pitch giving you 2700 RPM speed, or may be 2  knots 
faster at 2500 RPMS. Increasing the MT prop to 2700 gives you a  flatter 
pitch, no extra speed, more engine ware, less efficiency, among  other things 
I will leave to the experts. Short field take offs? You are  getting 2500 
static VS. the traditional Tiger 2150. My experience is about  a 30% 
reduction in feet over an obstacles. (Please lets not start this up,  but I 
am a definite believer in 1/3 flaps short fields.) The MT POH I  believe also 
reflects this, but is in meters and I haven't the time or  desire to convert 
the testing. VY? about the same. Quiet? like riding in a  car, with no or 
little vibration thus making most everything in the  aircraft live longer. 
Would I do it again? ONLY Probably because I go in  and out of a short strip 
regularly, but if were less expensive, it would  be worth it for many more 
reasons.

Andy Jensen
tigers 1975  models to 2002: 1600 hrs (200 on mt  prop)