Practicing SFLs with a constant speed prop - how?

I'm fairly new to GA after a 19 year break flying jets. I routinely
fly a single engine experimental with a constant speed prop mounted on
a Lycoming IO-360.

2 QUESTIONS:

1. What's the proper setup to simulate the way the plane would glide
in case of an engine failure? I'm looking for pitch and possibly a
manifold pressure number here.

2. It that motor quits, will it still rotate through the flying
airspeed envelope or can I expect it to stop rotation (assuming it's
not frozen due to a mechanical failure)?

In idle, with the prop at flat pitch, it feels too draggy and comes
down like a rock. With it at high pitch, it seems to have too
optimistic a glide ratio. What's the happy medium?

I don't live near a dry lake bed or I'd just shut it down and find
out. I have the proper airspeeds for max range and min sink out of
the POH but it does not quote any type of glide ratio.

Ed

"Ed" wrote in message
...
1. What's the proper setup to simulate the way the plane would glide
in case of an engine failure?

Generally, in a real engine failure with a constant speed prop, you'd pull
the RPM back to minimum. IMHO, your practice should match the *procedure*
you'll use in the real thing, even if the airplane performance doesn't,
since getting the procedure right is the most important thing.

Throttle to idle, to minimize the contribution of the engine to your glide,
of course.

2. It that motor quits, will it still rotate through the flying
airspeed envelope or can I expect it to stop rotation (assuming it's
not frozen due to a mechanical failure)?

It depends. But for most of the flight envelope, your prop will most likely
windmill. Each installation is different though. If you really want to
know, you either have to test it yourself, or talk to someone who has.

Pete

In article ,
Ed wrote:


1. What's the proper setup to simulate the way the plane would glide
in case of an engine failure? I'm looking for pitch and possibly a
manifold pressure number here.

IMO for practice you should leave the prop in the Hi RPM position so
that it provides plenty of drag. Regardless of how you simulate the
engine failure you will be getting some thrust from the engine which
does improve the glide performance. When the real thing happens you
could be caught short if expecting the performance you experienced when
practicing. Putting the prop to the Low RPM position should provide
less drag in an actual engine out situation.

The way I do deadstick landings is to put most of the drag out early and
stay very tight to the field. My thought is I can always get rid of
some drag if needed.

The way I've practiced and done them real life is to leave the prop at
Hi RPM. I also turn base abeam my intended landing point and put the
flaps down full. I fly an extremely tight pattern to prevent coming up
short. IF it appear I might be a little short I can reduce RPM on the
prop and/or reduce the flap setting some (Cessna 182/206) to reduce
drag. It's what I practiced and it's what has worked for me "real life".


2. It that motor quits, will it still rotate through the flying
airspeed envelope or can I expect it to stop rotation (assuming it's
not frozen due to a mechanical failure)?

The prop continued to turn until I was on the runway in all the engine
failures I've had.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

I can't say that I have tried every prop and engine combination, but I have
never been able to stop a prop without pulling the nose up to an alarming
attitude...you can pretty much count on it windmilling.

You are experiencing "flat plate drag." In cruise and reduced power descent,
the prop is pulling the airplane through the air (duh). As manifold pressure
is reduced toward idle, the prop governor flattens the pitch in an attempt
to maintain RPM, but when it hits the low pitch stops, that's all there is.
If you go all the way to idle, the windmilling prop drives the engine...the
crankshaft is turning, the pistons are doing their thing, etc, but no motive
force is produced.What you do get is disturbed air over the horizontal
stabilizer, reducing its effectiveness. You goal is to set the MAP to where
the prop is essentially idling, neither pulling nor creating drag. That will
be at about 11 inches in most cases. If you set up a long glide to final,
just as a test, play with the manifold pressure and if you have a sensitive
butt you will almost feel it when you have pulled the throttle back too far.

Bob Gardner

"Ed" wrote in message
...
I'm fairly new to GA after a 19 year break flying jets. I routinely
fly a single engine experimental with a constant speed prop mounted on
a Lycoming IO-360.

2 QUESTIONS:

1. What's the proper setup to simulate the way the plane would glide
in case of an engine failure? I'm looking for pitch and possibly a
manifold pressure number here.

2. It that motor quits, will it still rotate through the flying
airspeed envelope or can I expect it to stop rotation (assuming it's
not frozen due to a mechanical failure)?

In idle, with the prop at flat pitch, it feels too draggy and comes
down like a rock. With it at high pitch, it seems to have too
optimistic a glide ratio. What's the happy medium?

I don't live near a dry lake bed or I'd just shut it down and find
out. I have the proper airspeeds for max range and min sink out of
the POH but it does not quote any type of glide ratio.

Ed

Bob Gardner wrote:

I can't say that I have tried every prop and engine combination, but I have
never been able to stop a prop without pulling the nose up to an alarming
attitude...you can pretty much count on it windmilling.

One of the aviation writers (Schiff, IIRC) did some experiments along those lines. He
came to the conclusion that stopping the prop was only productive in terms of
improving glide distance if you were more than 6,000' AGL at the time the rubber band
broke. You have to get very close to stall speed to get it stopped. He was working
with fixed pitch propellors, however.

George Patterson
This marriage is off to a shaky start. The groom just asked the band to
play "Your cheatin' heart", and the bride just requested "Don't come home
a'drinkin' with lovin' on your mind".

On Mon, 12 Apr 2004 05:06:12 GMT, Ed wrote:

snip

In idle, with the prop at flat pitch, it feels too draggy and comes
down like a rock. With it at high pitch, it seems to have too
optimistic a glide ratio. What's the happy medium?

I'm a little confused by this portion of your question, and a couple
of the replies.

I have never actually messed around a bunch with airspeed/descent
rate/idle engine/prop rpm, but am pretty familiar with how a typical
pressure-to-increase pitch constant-speed prop/governor works.

Somewhere around 1600-1800 rpm, the prop governor ceases to output
enuff pressure to change/maintain the propeller pitch, and the
propeller goes to flat pitch. I've seen it on a gov bench, and on
approach-to-land.

Whether or not the engine is "running" if the rpm is below this range,
moving the prop control has no effect on the pitch of the prop.

TC

snip

"Ed" wrote in message
...
I'm fairly new to GA after a 19 year break flying jets. I routinely
fly a single engine experimental with a constant speed prop mounted on
a Lycoming IO-360.

2 QUESTIONS:

1. What's the proper setup to simulate the way the plane would glide
in case of an engine failure? I'm looking for pitch and possibly a
manifold pressure number here.

Unfortunately, it will be with the engine at idle at flat pitch. I will
explain why below.


2. It that motor quits, will it still rotate through the flying
airspeed envelope or can I expect it to stop rotation (assuming it's
not frozen due to a mechanical failure)?

In idle, with the prop at flat pitch, it feels too draggy and comes
down like a rock. With it at high pitch, it seems to have too
optimistic a glide ratio. What's the happy medium?


The prop pitch is maintained by oil pressure. Most single engine piston
installations set up the constant speed prop so that it will go to flat
pitch if oil pressure is lost (the exact opposite of turboprops and piston
twins). This is supposed to maximize your chances of restarting the engine,
but you pay for it with glide range. The propeller will continue to windmill
and create a lot of drag, but with the engine out you have little choice --
your oil pressure will be zero. It makes sense when you consider that most
'engine failures' are caused by fuel mismanagement. All you have to do is
switch tanks and with the windmilling prop your engine will start right up
again. You can make the propeller quit rotating by flying very slowly, but
that will not improve your glide.

Turboprops and piston twins set the prop to feather if oil pressure is lost.
These propellers will stop rotating almost immediately.

I don't live near a dry lake bed or I'd just shut it down and find
out. I have the proper airspeeds for max range and min sink out of
the POH but it does not quote any type of glide ratio.

You could just stay in the pattern and shut it down. It should start right
up again just by giving it some fuel.

In article , Dale
wrote:
IMO for practice you should leave the prop in the Hi RPM position so
that it provides plenty of drag. Regardless of how you simulate the
engine failure you will be getting some thrust from the engine which
does improve the glide performance. When the real thing happens you
could be caught short if expecting the performance you experienced when
practicing. Putting the prop to the Low RPM position should provide
less drag in an actual engine out situation.
The way I do deadstick landings is to put most of the drag out early and
stay very tight to the field. My thought is I can always get rid of
some drag if needed.
The way I've practiced and done them real life is to leave the prop at
Hi RPM. I also turn base abeam my intended landing point and put the
flaps down full. I fly an extremely tight pattern to prevent coming up
short. IF it appear I might be a little short I can reduce RPM on the
prop and/or reduce the flap setting some (Cessna 182/206) to reduce
drag. It's what I practiced and it's what has worked for me "real life".

The best way to simulate an engine failure without producing thrust is
to pull the mixture all the way out.
When you want to bring the power back, just push the mixture back in
and the engine will restart.

On Mon, 12 Apr 2004 16:21:39 -0700, "C J Campbell"
wrote:

snip

but you pay for it with glide range. The propeller will continue to windmill
and create a lot of drag, but with the engine out you have little choice --
your oil pressure will be zero. It makes sense when you consider that most

As long as there is oil in the engine, the oil system isn't
compromised, and the engine is windmilling oil pressure will remain
consistent with the rpm the engine is turning. The oil pump doesn't
care if it's being rotated by infernal combustion or by the wind
blowing through the prop.

Looked at a T-Arrow awhile back that fractured the turbo oil feed
fitting. Oil fire ignited, and was fed by the oil being pumped out of
the engine by the windmilling propeller until it ran out of oil.
Wasn't pretty, but the pilot walked away from it.

IMHO the rest of your info was right on the money.

Regards;

TC

snip

One caveat.. this works fine as long as the prop continues to windmill..
if it DOESNT... they you have just turned a training situation into what
may be a bonafide emergency.

Dave

EDR wrote:
In article , Dale
wrote:

IMO for practice you should leave the prop in the Hi RPM position so
that it provides plenty of drag. Regardless of how you simulate the
engine failure you will be getting some thrust from the engine which
does improve the glide performance. When the real thing happens you
could be caught short if expecting the performance you experienced when
practicing. Putting the prop to the Low RPM position should provide
less drag in an actual engine out situation.
The way I do deadstick landings is to put most of the drag out early and
stay very tight to the field. My thought is I can always get rid of
some drag if needed.
The way I've practiced and done them real life is to leave the prop at
Hi RPM. I also turn base abeam my intended landing point and put the
flaps down full. I fly an extremely tight pattern to prevent coming up
short. IF it appear I might be a little short I can reduce RPM on the
prop and/or reduce the flap setting some (Cessna 182/206) to reduce
drag. It's what I practiced and it's what has worked for me "real life".


The best way to simulate an engine failure without producing thrust is
to pull the mixture all the way out.
When you want to bring the power back, just push the mixture back in
and the engine will restart.