Today's Message Index:
----------------------
1. 03:24 AM - glide ratios (Jerry Painter)
2. 03:36 AM - Re: glide ratios (Rob Rowe)
3. 04:16 AM - Re: glide ratios (Ira Saligman)
4. 04:57 AM - Re: Re: glide ratios (A. Dennis Savarese)
5. 06:40 AM - Firewall fuel shut-off (was: glide ratios (Brian Lloyd)
6. 06:50 AM - Firewall fuel shut-off (was: Re: glide ratios) (Brian Lloyd)
7. 07:46 AM - Re: Firewall fuel shut-off (was: Re: glide ratios) (A. Dennis Savarese)
8. 09:58 AM - Re: Firewall fuel shut-off (was: Re: glide ratios) (Brian Lloyd)
9. 11:09 AM - safety wire (Jerry Painter)
10. 11:36 AM - Re: glide ratios (Valkyre1)
11. 12:43 PM - Re: glide ratios (Rob Rowe)
Message 1
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--> Yak-List message posted by: "Jerry Painter" <wild.blue@verizon.net>
Remember, the airplane Bud was flying was "Furias," a Hawker Sea Fury with a
Pratt & Whitney R-4360 engine and a monster prop, so his technique may not
be entirely applicable to the airplanes we fly, but probably pretty close.
Here's what he did:
1. He pulled up (actually, he'd already pulled up--s.o.p. at the end of a
race heat--that's when he discovered the problem) to give himself altitude
to work with, time to think and to reduce airspeed;
2. Pulled the prop all the way to low rpm. Since we're talking
engine-driven geared superchargers in Furias and our airplanes, too, that
also substantially reduces manifold pressure. Yak-52's and Nanchangs don't
have much propeller governing authority and pretty skinny blades (usually),
so the effect may not be as great as with the 4360, but you will reduce
power;
3. Pulled some substantial G's to load the airplane and increase induced
drag, further reducing speed to allow landing gear and flap extension;
4. Landed on the longest runway available. Pulled the mixture on short
final. On Furias the resulting power-off, full flap glide angle is seriously
nose low, so don't get excited and pull the mixture until you are absolutely
sure you will make the field. If you've never made a power off, full flap
landing in your CJ or -52 you may be surprised at the pitch angle needed to
maintain speed. Worth practicing every now and again.
5. You and I might want to obtain clean shorts. Bud got a drink of water
and continued with business.
The airplane and engine were undamaged. In fact, the throttle linkage was
re-connected and the airplane continued racing. In retrospect, this all
seems pretty elementary. However, when you're doing more than 400mph in an
airplane with a few thousand horsepower under the cowling, it's a little
different than the emergency landings you practiced years ago in a Cessna
150. The guys--and gals--that race at Reno not only have serious cojones,
they've got to be on top of emergency procedures for their airplanes and
pretty fair with the stick and rudder. Chances for very serious malfunction
are way high.
I agree that flipping the mag switch on and off is probably not a good idea.
Imagine the inertia of the huge prop on a 4360, or even on a CJ or -52, and
the loads from instantaneous full power torque reversals. I remember seeing
pictures several years ago of a CJ that had a sudden in-flight engine
stoppage. The crankshaft was twisted a whole bunch by the prop inertia
(though it remained attached--splined shaft, YMMV, esp w/flanged shaft).
WWI rotary engines were low-horsepower, low-compression and though they had
lots of engine rotating mass, also very low propeller mass and the
crankshaft was firmly attached to the firewall, so no great opposing forces
to be absorbed like a "normal" airplane engine.
My guess is the reason we shut down with ignition (esp HS-6/A) and full
throttle advance is that pulling the mixture won't shut the fuel off
sufficiently to obtain clean shutdown--a function of carburetor design. A
little residual fuel could result in dieseling, kickback and engine damage.
Again, what works for one engine, even with similar systems, may not work
for another.
It's easy to say "just jump" if something goes south. The problem is
knowing exactly what's wrong, what your options are and the probable results
of each. Why throw away a perfectly good airplane--especially your own--if
there's a reasonable chance of saving it? Reno racers don't have ejection
seats (except you L-39 guys, Barry). More than one has been killed trying
to jump. Reminds me of the story a friend told me about flying -105's in
Viet Nam. He was one of the original Wild Weasels. As sometimes happened,
they took a little damage. While my friend was pondering the question, his
GIB said "Let's get outa this SOB!," so they did. No sooner had they
departed the airplane than it went kablooey. If the GIB hadn't spoken up,
since everything seemed to be working OK, he would've continued on and not
be around to tell the story today.
Sometimes it's easier to let the taxpayers deal with it. Not so easy if it
s your pride and joy and you're just not quite sure what's happening...
Jerry Painter
Wild Blue Aviation
425-876-0865
wild.blue@verizon.net
http://mysite.verizon.net/res0cs5r/index.html
Message 2
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| Subject: | Re: glide ratios |
--> Yak-List message posted by: "Rob Rowe" <yak-list@robrowe.plus.com>
brian wrote:
> I still think you can modulate the power output with the fuel cut-off lever if
you are careful.
FWIW - a fellow -52 driver experimented with the fuel cut-off lever at ground idle
a couple of years back.
To his surprise it idled for several minutes before cutting out due to the c. 1
litre fuel reserve sat in the downstream compensation tank (the yellow sphere
on the firewall) ... so even at full throttle there could well be a (guesstimated)
15-20 seconds of full power available.
Equally on re-opening the fuel cut-off afterwards would require the fuel pump &
compensation tank to be re-primed before the pressure carb would function again
... this might take some time (and manual intervention!).
So speculate that the power latency between fuel shut-off & restoration might not
be conducive to the crisis at hand ... so maybe the mags are the more predictable
control to use after all.
As an aside - my understanding is that the fuel cut-off lever linkage is only engineered
to shut off & is not to be relied upon to re-open again ... to be kept
in mind even in an emergency.
Rob R
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=26834#26834
Message 3
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| Subject: | Re: glide ratios |
Has anyone timed how long it takes from closing the Fuel Shut Off until the
engine stops?
Ira Saligman
<mailto:isaligman@saligman.com> isaligman@saligman.com
Message 4
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| Subject: | Re: glide ratios |
--> Yak-List message posted by: "A. Dennis Savarese" <dsavarese@elmore.rr.com>
".....my understanding is that the fuel cut-off lever linkage is only
engineered to shut off & is not to be relied upon to re-open again."
I'd be very interested in hearing where you found that information Rob.
Dennis
----- Original Message -----
From: "Rob Rowe" <yak-list@robrowe.plus.com>
Sent: Friday, April 07, 2006 5:36 AM
Subject: Yak-List: Re: glide ratios
> --> Yak-List message posted by: "Rob Rowe" <yak-list@robrowe.plus.com>
>
>
> brian wrote:
>> I still think you can modulate the power output with the fuel cut-off
>> lever if you are careful.
>
>
> FWIW - a fellow -52 driver experimented with the fuel cut-off lever at
> ground idle a couple of years back.
>
> To his surprise it idled for several minutes before cutting out due to the
> c. 1 litre fuel reserve sat in the downstream compensation tank (the
> yellow sphere on the firewall) ... so even at full throttle there could
> well be a (guesstimated) 15-20 seconds of full power available.
>
> Equally on re-opening the fuel cut-off afterwards would require the fuel
> pump & compensation tank to be re-primed before the pressure carb would
> function again ... this might take some time (and manual intervention!).
>
> So speculate that the power latency between fuel shut-off & restoration
> might not be conducive to the crisis at hand ... so maybe the mags are the
> more predictable control to use after all.
>
> As an aside - my understanding is that the fuel cut-off lever linkage is
> only engineered to shut off & is not to be relied upon to re-open again
> ... to be kept in mind even in an emergency.
>
> Rob R
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=26834#26834
>
>
>
Message 5
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| Subject: | Firewall fuel shut-off (was: glide ratios |
--> Yak-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
Jerry Painter wrote:
> I agree that flipping the mag switch on and off is probably not a good idea.
> Imagine the inertia of the huge prop on a 4360, or even on a CJ or -52, and
> the loads from instantaneous full power torque reversals. I remember seeing
> pictures several years ago of a CJ that had a sudden in-flight engine
> stoppage. The crankshaft was twisted a whole bunch by the prop inertia
> (though it remained attached--splined shaft, YMMV, esp w/flanged shaft).
But that is not what we are talking about here. You are not getting a
sudden stoppage of all the moving mass in the engine and prop. They
continue to turn normally and none of that rotating momentum is
transferred to the airframe as it would be if the engine seized. All you
get is application and removal of the normal engine operating torque,
something you get whenever you move the throttle from closed to open and
back again. It just happens a little more quickly. If it causes damage
to your airplane then you were living on borrowed time anyway.
Ever stomped the throttle in your car to the floor suddenly or
completely removed your foot from the throttle suddenly? Same thing. It
doesn't break your car and it won't break your airplane either.
> WWI rotary engines were low-horsepower, low-compression and though they had
> lots of engine rotating mass, also very low propeller mass and the
> crankshaft was firmly attached to the firewall, so no great opposing forces
> to be absorbed like a "normal" airplane engine.
The rotating mass of the Gnome rotary even with a "low-mass" prop (I bet
that huge wooden club probably massed as much as our current crop of
props) is *HUGE* compared to our engines as the entire case is rotating
along with the prop, pistons, rods, cylinders, heads, valve train,
exhaust, etc. Only the crank remains stationary. That thing had
*enormous* rotating mass. That they could turn the mags on and off with
impunity tells you that this approach is not likely to break your
airplane or engine.
> My guess is the reason we shut down with ignition (esp HS-6/A) and full
> throttle advance is that pulling the mixture won't shut the fuel off
> sufficiently to obtain clean shutdown--a function of carburetor design. A
> little residual fuel could result in dieseling, kickback and engine damage.
> Again, what works for one engine, even with similar systems, may not work
> for another.
There is no idle cut-off circuit in the Chinese pressure carb. The
mixture control is not intended to shut the engine off. ICO is actually
an additional valve that completely turns off the flow of fuel to the
engine.
--
Brian Lloyd 361 Catterline Way
brian-yak at lloyd dot com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery
Message 6
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| Subject: | Re: Firewall fuel shut-off (was: Re: glide ratios) |
--> Yak-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
Rob Rowe wrote:
> FWIW - a fellow -52 driver experimented with the fuel cut-off lever at ground
idle a couple of years back.
>
> To his surprise it idled for several minutes before cutting out due to the c.
1 litre fuel reserve sat in the downstream compensation tank (the yellow sphere
on the firewall) ... so even at full throttle there could well be a (guesstimated)
15-20 seconds of full power available.
>
> Equally on re-opening the fuel cut-off afterwards would require the fuel pump
& compensation tank to be re-primed before the pressure carb would function again
... this might take some time (and manual intervention!).
>
> So speculate that the power latency between fuel shut-off & restoration might
not be conducive to the crisis at hand ... so maybe the mags are the more predictable
control to use after all.
I wasn't thinking of actually cutting the fuel on and off but rather
getting the valve into an intermediate position to reduce the flow of
fuel without cutting it off completely. At that point we would be
controlling power by starving the engine of fuel and running it way lean
to where it almost won't run. It will be rough as hell but it should put
out partial power.
And the more I think about it, the more I think that the mags are the
easiest way to deal with this. My only concern would be the *bang* as
the fuel/air mix in the exhaust lights off every time you turn the mags
back on again.
> As an aside - my understanding is that the fuel cut-off lever linkage is only
engineered to shut off & is not to be relied upon to re-open again ... to be
kept in mind even in an emergency.
There seems to be a *LOT* of supposition on this. On the CJ6A it is just
an on-off valve with detents at both the on and off positions. The valve
can be stopped at an intermediate position and is able to restrict the
flow of fuel to the engine. I haven't played with this valve in the
Yak-52 so I don't know if it behaves the same way. Someone (Dennis?) who
knows this valve needs to speak up and explain how it works and whether
it can be used to control the flow of fuel or whether it just cuts the
fuel completely off (hysteresis in the linkage prevents putting the
valve in an intermediate position).
--
Brian Lloyd 361 Catterline Way
brian-yak at lloyd dot com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery
Message 7
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| Subject: | Re: Firewall fuel shut-off (was: Re: glide ratios) |
--> Yak-List message posted by: "A. Dennis Savarese" <dsavarese@elmore.rr.com>
In the 52, the fuel shut off arm is pretty much like an over center type of
mechanism and is very difficult if not damn near impossible to move and hold
into a partially closed/partially opened position without physically
manhandling the control arm. I know that's true in my airplane. If you
haven't tried pulling the fire control/fuel shut off arm and place it in
some arbitrary midpoint position, try it and you'll see what I'm talking
about. Add to that the fact you are still trying to accomplish the #1 item
in the emergency checklist, which is to fly the airplane.
IMHO, try doing this on the ground with the brakes set and the airplane
chocked when you are totally cool, calm and collected and see what happens.
Then report your findings to the group. I'd be extremely interested in
reading about the results and your objective opinion as to whether you feel
you could accomplish what has been suggested during a real emergency.
Dennis
----- Original Message -----
From: "Brian Lloyd" <brian-yak@lloyd.com>
Sent: Friday, April 07, 2006 8:50 AM
Subject: Yak-List: Firewall fuel shut-off (was: Re: glide ratios)
> --> Yak-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
>
> Rob Rowe wrote:
>
>> FWIW - a fellow -52 driver experimented with the fuel cut-off lever at
>> ground idle a couple of years back. To his surprise it idled for several
>> minutes before cutting out due to the c. 1 litre fuel reserve sat in the
>> downstream compensation tank (the yellow sphere on the firewall) ... so
>> even at full throttle there could well be a (guesstimated) 15-20 seconds
>> of full power available.
>>
>> Equally on re-opening the fuel cut-off afterwards would require the fuel
>> pump & compensation tank to be re-primed before the pressure carb would
>> function again ... this might take some time (and manual intervention!).
>>
>> So speculate that the power latency between fuel shut-off & restoration
>> might not be conducive to the crisis at hand ... so maybe the mags are
>> the more predictable control to use after all.
>
> I wasn't thinking of actually cutting the fuel on and off but rather
> getting the valve into an intermediate position to reduce the flow of fuel
> without cutting it off completely. At that point we would be controlling
> power by starving the engine of fuel and running it way lean to where it
> almost won't run. It will be rough as hell but it should put out partial
> power.
>
> And the more I think about it, the more I think that the mags are the
> easiest way to deal with this. My only concern would be the *bang* as the
> fuel/air mix in the exhaust lights off every time you turn the mags back
> on again.
>
>> As an aside - my understanding is that the fuel cut-off lever linkage is
>> only engineered to shut off & is not to be relied upon to re-open again
>> ... to be kept in mind even in an emergency.
>
> There seems to be a *LOT* of supposition on this. On the CJ6A it is just
> an on-off valve with detents at both the on and off positions. The valve
> can be stopped at an intermediate position and is able to restrict the
> flow of fuel to the engine. I haven't played with this valve in the Yak-52
> so I don't know if it behaves the same way. Someone (Dennis?) who knows
> this valve needs to speak up and explain how it works and whether it can
> be used to control the flow of fuel or whether it just cuts the fuel
> completely off (hysteresis in the linkage prevents putting the valve in an
> intermediate position).
>
> --
> Brian Lloyd 361 Catterline Way
> brian-yak at lloyd dot com Folsom, CA 95630
> +1.916.367.2131 (voice) +1.270.912.0788 (fax)
>
> I fly because it releases my mind from the tyranny of petty things . . .
> - Antoine de Saint-Exupery
>
>
> http://www.matronics.com/Navigator?Yak-List
> http://wiki.matronics.com
>
>
>
Message 8
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| Subject: | Re: Firewall fuel shut-off (was: Re: glide ratios) |
--> Yak-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
A. Dennis Savarese wrote:
> --> Yak-List message posted by: "A. Dennis Savarese"
> <dsavarese@elmore.rr.com>
>
> In the 52, the fuel shut off arm is pretty much like an over center type
> of mechanism and is very difficult if not damn near impossible to move
> and hold into a partially closed/partially opened position without
> physically manhandling the control arm. I know that's true in my
> airplane. If you haven't tried pulling the fire control/fuel shut off
> arm and place it in some arbitrary midpoint position, try it and you'll
> see what I'm talking about. Add to that the fact you are still trying
> to accomplish the #1 item in the emergency checklist, which is to fly
> the airplane.
And that is a good point. It is going to be both sensitive and unstable,
not exactly the thing that will be easiest to use in flight. Add to that
the fact that the engine power output is going to vary hugely with only
a very small change in mixture and it will be even more sensitive.
Still, in an emergency it is good to know all the options.
> IMHO, try doing this on the ground with the brakes set and the airplane
> chocked when you are totally cool, calm and collected and see what
> happens. Then report your findings to the group. I'd be extremely
> interested in reading about the results and your objective opinion as to
> whether you feel you could accomplish what has been suggested during a
> real emergency.
I agree. Controlled experimentation would be useful before you have to
use it in real life.
I remember being told by just about everyone that I should *never*
attempt a turn-back to the airport if the engine quits. I remember
thinking that a blanket admonition might be wrong so I went out and
tried it for myself under controlled circumstances. I discovered that,
in my Grumman Tiger, it was safe to turn back to the runway from any
altitude above 400' if the engine quit while on upwind. I also
discovered that, in my Piper Clipper or Piper Comanche it was not safe
to turn back if the engine quit on upwind at any altitude.
So you really do need to figure some of these things out on an
airplane-by-airplane basis.
Brian
Message 9
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--> Yak-List message posted by: "Jerry Painter" <wild.blue@verizon.net>
Sometimes we forget that our our spicy little airplanes are just podunk
primary trainers to the military--and that the trainee is sitting up front
with most of the controls, like fuel on/off. That's why us IP's are paid so
much to sit in the back. And the fan in front is just there to cool the
instructor until the trainee breaks the wire--then watch him sweat. ha ha
Jerry Painter
Wild Blue Aviation
425-876-0865
wild.blue@verizon.net
http://mysite.verizon.net/res0cs5r/index.html
Message 10
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| Subject: | Re: glide ratios |
Thanks Cliff. Good Point. I knew that a 360hp engine had to have a downside somewhere.
Other than that and the molecular changes inherent to aging metal, I
can't think of a better previous owner than Jeff "Linedog" as far as treating
my CJ6 well.
Guess I'll just have to review my options as well as do a very thorough pre flight
at all times.
I've only had one negative experience in light airplanes with fuel controls. That
was when I was instructing in a Cessna 150 and had the mixture control come
out in my hand while shutting down. Of course it didn't shut down (no I didn't
use my inhuman strength to yank the thing out). That was more of a humorous
experience and at least I could get out, open the cowl and mechanically shut
it down. Things do tend to loosen up what with all of the yanking, banking and
vibration.
- Val
Message 11
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| Subject: | Re: glide ratios |
--> Yak-List message posted by: "Rob Rowe" <yak-list@robrowe.plus.com>
dsavarese(at)elmore.rr.co wrote:
> ".....my understanding is that the fuel cut-off lever linkage is only
> engineered to shut off & is not to be relied upon to re-open again."
>
> I'd be very interested in hearing where you found that information Rob.
> Dennis
>
> ---
Dennis
I amended my original web posting within a few minutes to remove the "only" as
I realised it misconstrued a one-way operation by design, but guess web edits
don't get cascaded into the email list.
While the YAK-52 fuel valve has a distinct binary operation which should snap on
or off reliably, it's the control linkage that may not be so dependable when
being "pushed" on versus being "pulled" shut.
This arose from a discussion I had with a Lithuanian engineer some 18 months ago
when I was researching the fuel system's operation.
Rob R
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=26889#26889
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