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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 -----
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
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