Message-ID: <4070CD37.20306@netdoor.com>
Date: Sun, 04 Apr 2004 22:06:31 -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
References: <list-3145605@logan.com>
In-Reply-To: <list-3145605@logan.com>
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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
>  
>