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Date: Mon, 20 Dec 2004 11:34:08 -0700
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: George Graham glide update
Message-Id: <20041220113408.3ff27833.bob@bob-white.com>
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I find that when I state an opinion (make a guess) like that, I can get
immediate feedback on the error of my ways. :)  Lynn has given the exact
answer I would have last week before there were several comments to the
effect that a spinning propeller seemed to have little effect on gide
performance.  It then seems necessary to think about why that answer is
thought to be true, and what is different in the reported conditions. 
20 miles from 5000 ft must have involved some very favorable conditions.

I'm not sure I understand everything involved yet.  It does seem that a
fixed pitch prop isn't as much of a problem as I thought it would be. 
In general, at best glide speed, the FP prop will stop anyway if it has
to turn the engine.

This really is a great place to find out about anything concerning
flying rotaries.

Can you powder coat over the old powder coat without removing it?  High
temperature paint works pretty good if it will stick to the powder coat.
A friend of mine painted a homemade wood stove with high temp red paint.
It stood up very well.

Bob White


On Sun, 19 Dec 2004 21:14:53 -0800 (PST)
Tom <tomtugan@yahoo.com> wrote:

> I'm glad I only went as far as saying they might differ.   Gyrocopters
> have free-wheeling blades, they would probably descend a 'bit' quicker
> if the blades stopped rotating.    
> 
> There really are posts here which have more useful info.  I've spent a
> few hours today and a couple yesterday going thru them and capturing
> and organizing info.   Break-in oils, oil-thermostats, fuel-injector
> stuff, soft-mounting stock Mazda oil coolers, MMO, A/F indicators,
> intake manifold lengths and configurations, ignition coil wire types,
> ... I'm actually feeling good about being able to have a good
> installation that'll work reliably despite my lack of any background. 
>   Something I'd like to find is 'how to remove powder coating
> from a motor'.  Gold was a bad choice, I'd have less other parts to
> paint if the motor were silver and blue.   I'll probably simply
> repaint over the gold.  
>        
> 
> Tom
> 
> 
> --- Bob White <bob@bob-white.com> wrote:
> 
> > I suspect they would be different.  To hazard a guess, a free
> > spinning prop is doing less work than a prop turning a motor, so it
> > should provide less drag. But a fixed pitch prop in either condition
> > would want to turn somewhere in the range of speed you would be
> > gliding at.  A prop at flat pitch would need to speed up to a very
> > high rpm to match the forward speed of the plane.  If the prop can't
> > keep up with the forward speed of the plane, it will effectively be
> > pushing backward creating extra drag.  At least that's my armchair
> > analysis.  
> > 
> > Bob White
> > 
> > On Sun, 19 Dec 2004 18:10:25 -0800 (PST)
> > Tom <tomtugan@yahoo.com> wrote:
> > 
> > > I wonder if a free-spinning prop on a broken tranny would not have
> > > the same drag as a spinning prop which is turning the motor?   
> > > I'd be inclined to say they would differ. 
> > > 
> > > Tom
> > > 
> > > 
> > > --- Bob White <bob@bob-white.com> wrote:
> > > 
> > > > Somenone else recently reported a spinning prop having
> > > > negligable effect on engine out glide.  (Dave Leonard maybe?). 
> > > > I'm thinking that the biggest effect occurs with a C/S prop that
> > > > goes to flat pitch when it looses oil pressure.  I think twins
> > > > often use feathering props for that reason.
> > > > 
> > > > Bob White
> > > > 
> > > > On Sun, 19 Dec 2004 15:41:53 -0500
> > > > "Tracy Crook" <lors01@msn.com> wrote:
> > > > 
> > > >  He glided about 20 miles from an altitude of only 5000 ft with
> > > >  the prop
> > > > freewheeling!   I've heard several times that a freewheeling
> > > > prop (no engine drag on it) would generate lots of drag. 
> > > > Another sacred cow shot down : )
> > > > > 
> > > > > Tracy 
> > > > 
> > > > -- 
> > > > http://www.bob-white.com
> > > > N93BD - Rotary Powered BD-4 (soon)
> > > > 
> > > > >>  Homepage:  http://www.flyrotary.com/
> > > > >>  Archive:  
> > > > >http://lancaironline.net/lists/flyrotary/List.html
> > > > 
> > > 
> > > 
>

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