Message-ID: <4073557B.8030703@netdoor.com>
Date: Tue, 06 Apr 2004 20:12:27 -0500
From: Charlie & Tupper England <cengland@netdoor.com>
Reply-To: cengland@netdoor.com
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: idle speeds (prop stopped flight)
References: <list-3146496@logan.com>
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Hi Bernie,

What was your idle speed (plane stationary on the ground) on the Lyc? 
Would the results have been the same if you had set the idle speed to 
850-900 rpm & then flown the same test idling & stopped prop?


WALTER KERR wrote:

> Hi Charlie,
>  
> I had a cruise prop (80 inch pitch) sensenich metal prop on the 6A. 
> When I was doing engine off glide testing, some thought I would do 
> better with engine stopped rather than turning. Really had to slow way 
> down to get prop to stop. Could not measure the difference in glide 
> engine stopped or windmilling. Really had to go fast, over a hundred 
> to get it going again!
>  
> Bernie Kerr, painting the 9A waiting to get rotary back from Bruce T 
> at SnF
>
>     ----- Original Message -----
>     From: Charlie & Tupper England <mailto:cengland@netdoor.com>
>     To: Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
>     Sent: Sunday, April 04, 2004 11:06 PM
>     Subject: [FlyRotary] Re: idle speeds
>
>     I agree with Jim about this. I've had similar problems with a Lyc
>     powered  RV-4. Anything over about 800 prop rpm caused a lot of
>     float.
>     I'd be interested to see the calculations on whether a really highly
>     pitched cruise prop is producing thrust at 800-850 rpm &  60-70mph. I
>     think that it's at least safe to say that the airflow isn't
>     driving the
>     prop disc & producing drag like a climb or c/s prop.
>
>     I wonder what engine-stopped glide angle would look like compared
>     to the
>     angle we get used to while being pulled along by the engine on final.
>     This could be a significant safety issue if there's an engine failure
>     when we have become acclimated to unknowingly carrying power
>     (thrust) on
>     final.
>
>     Charlie
>
>
>
>     Jim Sower wrote:
>
>     > <... I need to get the idle speed way down ...>
>     > You sure do.  I've regaled you several times about my EZ with an
>     O-235
>     > idling at 800-900 rpm that could NEVER be slowed down enough to
>     land -
>     > floated 1000' or more down every damned runway I encountered. 
>     Landed
>     > fine when I set the idle down to 500-600 rpm.  Ran rough as a
>     cob at
>     > that speed on the ground (which is why it had been set so high),
>     but I
>     > could advance it to 800 for ground ops, and go to the idle stop on
>     > final.  With all your power, I would emphatically recommend that
>     you
>     > back the idle down till it will just barely idle on the ground. 
>     You
>     > can always taxi above the idle stop, but you can never land
>     below it. 
>     > I would also strongly recommend a shutdown switch (injectors? 
>     pumps?)
>     > near the throttle quadrant for convenient shutdown on final.  A
>     > guarded switch (guarded ON) would satisfy safety considerations,
>     and
>     > be convenient enough that you could shut down nearly as easily as
>     > pulling the mixture.
>     >
>     > That way, you have all the bases covered ... Jim S.
>     > 
>     >
>     > John Slade wrote:
>     >
>     >> Last week we had some discussion on idle speeds, and I think the
>     >> consensus
>     >> was to keep it around 2000 or a little under. Just for information
>     >> for other
>     >> canard pusher people, I think 2000 is going to be a real
>     problem for
>     >> me. At
>     >> the current 1850 setting with the big 3 66/84 prop I have on she's
>     >> pushing
>     >> hard against the brakes. I think I could taxi the length of the
>     >> runway at
>     >> idle and be doing 30/40 kts at the end. On a short (3400)
>     runway the
>     >> only
>     >> way to stop might be kill the engine once on the ground, or
>     even on
>     >> short
>     >> final. So I need to get the idle speed way down.
>     >> John Slade (more power than I know what to do with)
>     >>
>     >> >>  Homepage:  http://www.flyrotary.com/
>     >> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>     >>
>     > --
>     > Jim Sower ... Destiny's Plaything
>     > Crossville, TN; Chapter 5
>     > Long-EZ N83RT, Velocity N4095T
>     > 
>     >
>
>
>
>     >>  Homepage:  http://www.flyrotary.com/
>     >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>