Multi Blade Props at Nats

[David Lockhart]

Wayne,

I have spoke to APC on several occasions - it is very unlikely that any 
additional 3 blade props will be added to the line in the near future.  
Production costs on the 3 bladers is much higher and the sales volumes 
on them is much lower (think order of magnitude lower).  Of course, if 
enough people inquired about the 3 blade, and promised to buy 
them.........

I have not personally spent much time with the Mintor 170 - but from 
what I have seen, I think the 3 blade would likely work very well - at 
11 or 12 pitch for sure, and maybe at a 13 pitch (depending on what 
exhaust system and tune length, fuel, density altitude, etc).

At the Team Trials, Jason ran a 15.75-12 3 blade (repitched by me) on 
his OS160FI and it worked quite well - I believe he had also tried the 
stock 15.75-13 and found it performed well, but was a bit quick for his 
taste in the downlines of the FAI schedules (likely not a problem for 
any of the other schedules).

So far as 3 blades versus 4 - all other things being equal, increasing 
the number of blades should reduce prop efficiency - other factors 
(airfoils and planform of prop, torque curve of engine, etc) may make 
the comparison difficult, however.

Regards,

Dave 



----- Original Message -----
From: adriancwong at earthlink.net
Date: Monday, July 21, 2003 2:07 am
Subject: Re: Re: Multi Blade Props at Nats

> I have tried both the 13.4 X 13.5 three blades, and the 13.8 X 10 
> four blades on the L and found the 4 blades is much more efficient 
> than the 3 blades.
> 
> Adrian
> 
> 
> -------Original Message-------
> From: wgalligan <wgalligan at cnbcom.net>
> Sent: 07/20/03 07:52 PM
> To: discussion at nsrca.org
> Subject: Re: Multi Blade Props at Nats
> 
> > 
> > Dave,
> 
> Do you think there is any chance that APC will be making a lower pitch
> three
> blade in the near future?
> And would this prop be as effective on the standard O.S.?   I have a
> Mintor
> 1.70 ready to go and do you think the 3 bladed 13 pitch prop would 
> be a
> good
> match for this engine that has the good low end and mid range grunt?
> 
> Wayne G.
> 
> -----Original Message-----
> From: David Lockhart <DaveL322 at comcast.net>
> To: discussion at nsrca.org <discussion at nsrca.org>
> Date: Sunday, July 20, 2003 10:53 PM
> Subject: Re: Multi Blade Props at Nats
> 
> 
> 15.75-11  blade (re-pitched from 15.75-13)
> OS 10 EFI
> Asano Header and pipe
> S&W 20/20
> 7900/7700/1500 - Peak/launch/idle RPM
> 10 lb 13 oz EMC
> Typically less than 90 dB
> 
> I did switch to a 17-12N in the extreme wind on Tuesday - which 
> was the
> 1st time I have used a 2 blade in a contest since working up the 
> 15.75-
> 11.  Speed control with the 15.75-11 is very easy - it is not super
> sensitive to throttle position and brakes very well.
> 
> Dave
> DaveL22 at comcast.net
> 
> ----- Original Message -----
> From: RUDDERCABL at aol.com
> Date: Sunday, July 20, 2003 10:08 pm
> Subject: Re: Multi Blade Props at Nats
> 
> > In a message dated 7/20/2003 9:18:36 PM Eastern Standard Time,
> > rcaerobob at cox.net writes:
> >
> > > Yeah, Dave wrote me about his.  It is one of the custom twist
> > jobbies that
> > > he makes...bet it worked just fine.
> > >     Any others?
> > >
> > >
> > >
> >
> > Bob
> >
> > Dave used that prop at team selection also. Very quiet and pulls
> > well . Nice
> > combination with his plane and engine .
> > I also used an APC  15x13W  3 blade on my OS1.40 powered Focus . I
> > liked the
> > results of this combo but changed to 2 blade on Tuesday when the
> > wind blew so
> > hard. I believe Dave also went back to a 2 blade in the extreme
> > wind .
> > I don't know if any-one else used one .
> >
> > Robert
> >
> 
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