Practicing SFLs with a constant speed prop - how?

[Ed]

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

[Peter Duniho]

Post by Ed
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.

Post by Ed
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

[Dale]

Post by Ed
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".

Post by Ed
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.

[EDR]

Post by Dale
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.

[Dave S]

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

Post by EDR

Post by Dale
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.

[Dylan Smith]

Post by Dave S
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.

I believe Highflyer has a story about that in a Taylorcraft...which
lacked an electric starter, and the prop had stopped turning. Slope
soaring saved the day.

[Bob Gardner]

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

Post by Ed
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.
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

[G.R. Patterson III]

Post by Bob Gardner
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".

[t***@yahoo.com]

On Mon, 12 Apr 2004 05:06:12 GMT, Ed <***@yahoo.com> wrote:

snip

Post by Ed
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

[Dale]

Post by t***@yahoo.com
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.

That's what I thought until I tried it on my 182. Idle power, trimmed
stable 80 mph glide with the prop control all the way forward. Pulled
the blue knob back and watched the airspeed increase about 5MPH...pushed
the blue knob in and I slowed again.

[Roy Epperson]

With our Mooney F model at best glide speed when I pull the prop control all
the way back (max pitch), it saves me about 300 fpm while maintaining best
glide. With a minimum pitch, the blades are one big braking force.

Post by Dale

Post by t***@yahoo.com
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.

That's what I thought until I tried it on my 182. Idle power, trimmed
stable 80 mph glide with the prop control all the way forward. Pulled
the blue knob back and watched the airspeed increase about 5MPH...pushed
the blue knob in and I slowed again.
--
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

[t***@yahoo.com]

Post by Roy Epperson
With our Mooney F model at best glide speed when I pull the prop control all
the way back (max pitch), it saves me about 300 fpm while maintaining best
glide. With a minimum pitch, the blades are one big braking force.

I'll gladly take your collective word for it from in-flight
observations.

Mine were limited to shoving the prop ahead turning final (in every
complex aircraft I've ever flown in) at approx 1200-1400 rpm (prop
control previously set to 2300 in cruise) with no change in engine
rpm/prop noise noted.

Have pulled mis-rigged PT6A props to "flat" on short final a couple of
times, have the stained shorts to prove it.

Before I posted, I called my gov shop buddy to make sure his views
coincided with what I remembered from hanging around in his shop. He
related same, that the gov bench doesn't indicate useable gov pressure
until around 1500-1600 rpm. As I recall, on most engines, the gov
drive turns at about 90% of the indicated rpm.

I stuff I work on now has a fixed-pitch first stage "prop", and I
ain't allowed to drive it, so I can't add anything further.

Regards;

TC

[Peter Duniho]

Post by t***@yahoo.com
Mine were limited to shoving the prop ahead turning final (in every
complex aircraft I've ever flown in) at approx 1200-1400 rpm (prop
control previously set to 2300 in cruise) with no change in engine
rpm/prop noise noted.

That's a completely different situation. At that power setting, the engine
didn't have enough power to drive the prop at the selected RPM (2300), and
so the blades were already at flat pitch. Selecting high RPM would have had
no effect, since the governor was already trying to increase RPM, to its
limits (maximum flat pitch).

Next time, pull the prop to *minimum* RPM and see your glide angle decrease.

Post by t***@yahoo.com
Have pulled mis-rigged PT6A props to "flat" on short final a couple of
times, have the stained shorts to prove it.

Not sure how that statement fits in to the discussion, but the PT6 governors
work differently from those found on most piston-engine singles.

Post by t***@yahoo.com
Before I posted, I called my gov shop buddy to make sure his views
coincided with what I remembered from hanging around in his shop. He
related same, that the gov bench doesn't indicate useable gov pressure
until around 1500-1600 rpm.

You mentioned "gov pressure" in an earlier post, and I still don't
understand what you mean. The force to change the prop blade angle comes
from springs and oil pressure, not the governor itself. All the governor
does is adjust oil valves to control how the oil moves through the pitch
change mechanism.

In any case, as with the others, I've had no trouble at all reducing the
blade pitch even in low-RPM, idle-power situations. I have no reason to
expect I'd have any trouble in an actual engine failure, assuming the engine
continued to windmill and run the oil pump.

Pete

[t***@yahoo.com]

On Tue, 13 Apr 2004 16:15:11 -0700, "Peter Duniho"
<***@NnOwSlPiAnMk.com> wrote:

snip

Post by Peter Duniho
Next time, pull the prop to *minimum* RPM and see your glide angle decrease.

It'll likely be years, I don't do GA anymore.

Post by Peter Duniho

Post by t***@yahoo.com
Have pulled mis-rigged PT6A props to "flat" on short final a couple of
times, have the stained shorts to prove it.

Not sure how that statement fits in to the discussion, but the PT6 governors
work differently from those found on most piston-engine singles.

Doesn't have anything to do with it, this is Usenet. You really owe to
yourself to try it once, though. It's similiar to tromping on a
non-ABS brake pedal at 40 mph. Gets your attention at 75 feet AGL with
the nose down coming-over-the-fence.

Post by Peter Duniho

Post by t***@yahoo.com
Before I posted, I called my gov shop buddy to make sure his views
coincided with what I remembered from hanging around in his shop. He
related same, that the gov bench doesn't indicate useable gov pressure
until around 1500-1600 rpm.

You mentioned "gov pressure" in an earlier post, and I still don't
understand what you mean. The force to change the prop blade angle comes
from springs and oil pressure, not the governor itself. All the governor
does is adjust oil valves to control how the oil moves through the pitch
change mechanism.

The base of a governor is another oil pump, stepping up engine oil
pressure to over 175 psi. Maximum pressure is limited by a
spring-loaded pop-off valve, just like the engine oil pump.

http://www.mccauley.textron.com/prop/prop-tech/pg03govern.html

was the best picture I could find of it in a 30 second Google.

Post by Peter Duniho
In any case, as with the others, I've had no trouble at all reducing the
blade pitch even in low-RPM, idle-power situations. I have no reason to
expect I'd have any trouble in an actual engine failure, assuming the engine
continued to windmill and run the oil pump.

Agreed, like I indicated in another post, the oil pump/governor
doesn't care what's turning it.

TC

[Peter Duniho]

Post by t***@yahoo.com

Post by Peter Duniho
Not sure how that statement fits in to the discussion, but the PT6 governors
work differently from those found on most piston-engine singles.

Doesn't have anything to do with it, this is Usenet.

Okay...just thought I'd ask.

Post by t***@yahoo.com
The base of a governor is another oil pump, stepping up engine oil
pressure to over 175 psi. Maximum pressure is limited by a
spring-loaded pop-off valve, just like the engine oil pump.

Yes, but as far as I know, that pump will work just as well as the engine
pump. Also, even if for some reason that pump failed, my understanding is
that it would simply reduce the responsiveness of the governor. It wouldn't
cause it to stop working altogether. The engine-supplied oil pressure would
be sufficient.

Post by t***@yahoo.com
Agreed, like I indicated in another post, the oil pump/governor
doesn't care what's turning it.

Well, color me confused then. I thought we started this thread with you
suggesting that if the engine has failed, resulting in low RPM, you wouldn't
be able to get the prop to the coarse pitch setting.

But, if you agree with what I said, so much the better. :)

Pete

[t***@yahoo.com]

Post by Peter Duniho

Post by t***@yahoo.com

Post by Peter Duniho
Not sure how that statement fits in to the discussion, but the PT6

governors

Post by t***@yahoo.com

Post by Peter Duniho
work differently from those found on most piston-engine singles.

Doesn't have anything to do with it, this is Usenet.

Okay...just thought I'd ask.

Not a problem.

Post by Peter Duniho

Post by t***@yahoo.com
The base of a governor is another oil pump, stepping up engine oil
pressure to over 175 psi. Maximum pressure is limited by a
spring-loaded pop-off valve, just like the engine oil pump.

Yes, but as far as I know, that pump will work just as well as the engine
pump. Also, even if for some reason that pump failed, my understanding is
that it would simply reduce the responsiveness of the governor. It wouldn't
cause it to stop working altogether. The engine-supplied oil pressure would
be sufficient.

I really would like to spend 24 hours in your world. Having spent 20+
years living in aviation, I'm still learning. IMHO it becomes quite
obvious from reading your posts that airplane ownership has somehow
mysteriously given you insight that mere mortals such as myself are
sorely lacking.

Where did you obtain the basis for this theory? I somehow doubt that
you've ever had to troubleshoot/repair a prop/governor gripe. If you
had, and had done your homework, you would have learned that one of
the first steps in troubleshooting is verifying adequate oil pressure
(also a crude method of determining adequate oil volume) to the prop
governor. Please bear in mind, in a lot of engine designs, the prop
governor is located at the tail end of the oil system, with a lot of
built-in leaks between the engine oil pump and the governor pad.

I find it rather funny that while the prop/governor will not function
properly without approximately 30-40 psi to "step-up" to over 175 psi,
you have determined that the governor oil pump (which initially you
apparently doubted even existed) is not a necessary piece of the
puzzle.

Speaking from direct observation, at higher power settings,
reduced/insufficient governor pressure delivered to the propeller dome
can limit the ability to reduce engine rpm in a pressure-to-increase
pitch system, and failure to obtain maximum rpm in a
pressure-to-decrease system.

Again, from direct observation, this can be caused by insufficient oil
supply to the gov pad (see above), excessive rotor-to-housing
clearance/physical gov oil pump damage, a fault in the oil pressure
relief valve, or in extreme cases, excessive clearances/oil loss
between the main crankshaft bearing and the crankshaft.

Post by Peter Duniho

Post by t***@yahoo.com
Agreed, like I indicated in another post, the oil pump/governor
doesn't care what's turning it.

Well, color me confused then. I thought we started this thread with you
suggesting that if the engine has failed, resulting in low RPM, you wouldn't
be able to get the prop to the coarse pitch setting.

That's entirely correct. I described my personal experiences
in-flight, related that they were somewhat limited to the subject, and
that I needed clarification. I also contacted two professional GA
pilots, and a guy that has been repairing/overhauling prop governors
for 20 years prior to posting.

After reading subsequent replies, I freely admitted that I was wrong.
Now I can factor that information into my personal database for future
reference. Seeking new knowledge/other experiences was one of the
primary reasons I climbed into the stinking swamp of GA on the
internet to begin with.

The other primary reason was to share my experiences and knowledge
with no intention of financial gain. Over the years in these forums,
my chosen profession has been repeatedly attacked, my personal
experience and intent questioned.

After spirited credentialled discourse with apparently clueless twits,
surprisingly enuff I began to receive private communications from
lurkers (and posters) who wanted me to maintain their aircraft. As
this was never my intention, I had to become the anonymous
self-proclaimed hairy mole on the ass that is rec.aviation.

You see, I learned a long, long time ago that arguing on the Internet
is like getting a gold medal in the Special Olympics. You (figure of
speech, by no means a personal attack)may have "won", but you (along
with all the other contestants) are still mentally-challenged.

Post by Peter Duniho
But, if you agree with what I said, so much the better. :)

I share your joy;

TC

[Peter Duniho]

[...] Again, from direct observation, this can be caused by insufficient

oil

supply to the gov pad (see above), excessive rotor-to-housing
clearance/physical gov oil pump damage, a fault in the oil pressure
relief valve, or in extreme cases, excessive clearances/oil loss
between the main crankshaft bearing and the crankshaft.

Your oh-so-respectful approach to your criticism notwithstanding (full of
insults and personal mischaracterizations), I think it's interesting you
don't bother to list "low RPM" as a fault that could interfere with prop
governing.

[...] Over the years in these forums,
my chosen profession has been repeatedly attacked, my personal
experience and intent questioned.

So, you choose to propogate the madness? IMHO, once you start doing it
yourself, you lose the right to complain about others doing it to you.

Pete

[t***@yahoo.com]

On Wed, 14 Apr 2004 09:55:51 -0700, "Peter Duniho"

Post by Peter Duniho
Your oh-so-respectful approach to your criticism notwithstanding (full of
insults and personal mischaracterizations), I think it's interesting you
don't bother to list "low RPM" as a fault that could interfere with prop
governing.

Nice edit job. I was really looking forward to re-reading all the
"insults and personal mischaracterizations".

Well ya see, noone driving a single-engine has ever walked into the
hangar with a gripe about "nothing happening" when they pulled the
prop control back at idle while practicing engine-outs. If it had
happened, up until a day or so ago, I would have told them it was
normal.

Post by Peter Duniho

[...] Over the years in these forums,
my chosen profession has been repeatedly attacked, my personal
experience and intent questioned.

So, you choose to propogate the madness? IMHO, once you start doing it
yourself, you lose the right to complain about others doing it to you.

I don't live in a glass house (work in GA) any more, so I can throw
stones whenever the mood strikes me.

BTW it would tend to be a little more interesting/challenging if your
apparent "personality" was unique in this industry. Sadly, it is not.

Speaking theoretically of course, a few years ago had you strolled
into the hangar and handed me the attitude you tend to exhibit online,
I wouldn't have been able to laugh my ass off until after you had
walked back out.

Can you hear me now?

TC

[Ed]

I don't buy that. I can play with the prop at IDLE and zero knots and
get it to change RPM. My run-up is done at 1700 and the prop oil wash
exercise has a big effect.

Ed

Post by t***@yahoo.com
snip

Post by Ed
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

[C J Campbell]

Post by Ed
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.
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.

Post by Ed
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.

Post by Ed
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.

[t***@yahoo.com]

On Mon, 12 Apr 2004 16:21:39 -0700, "C J Campbell"
<***@hotmail.com> wrote:

snip

Post by C J Campbell
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

[Ed]

I just want to clear this up. My home field (O17) - and just about
all those around it for 50nm are heavily wooded and surrounded by
pines reaching up about 50'.

Some of you guys are men to faith, obviously. I however, am not and
prefer to try to perfect the simulation rather than log glider time.
My goal is simply to set it up so the configuration for best glide or
min sink (depending on distance to the runway) so as to get a feel for
expected glide performance.

Thanks for all the various suggestions. It convinces me there is not
any one procedure past what the POH says about getting the motor
started again and then technique becomes the rule.

Ed (N119NC)

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

Post by C J Campbell

Post by Ed
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.
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.

Post by Ed
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.

Post by Ed
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.

[Bushleague]

I don't have a lot of propeller driven time (4250 hrs maybe) however
most AFM's give you a setting to simulate 'zero thrust'. Since the
throttle is retarted and your'e out of the prop governor range, the
propeller lever is full foraward, and the manifold 15" or so on the
Lycoming. Of course I may be off a bit and any input is welcome here.

Have a great one!

Bush

Post by Ed
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.
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