Today's Message Index:
----------------------
1. 02:22 AM - range (Mark Jefferies YAK UK Ltd)
2. 02:27 AM - Re: FOD for thought... (Jorgen Nielsen @ Mweb)
3. 05:16 AM - Re: FOD for thought... (A. Dennis Savarese)
4. 05:25 AM - Re: range (Gus Fraser)
5. 05:29 AM - Re: FOD for thought... (Gus Fraser)
6. 05:30 AM - Re: Yak 50 help needed (Gus Fraser)
7. 05:40 AM - Re: FOD for thought... (A. Dennis Savarese)
8. 06:02 AM - Wildcat gone (cjpilot710@aol.com)
9. 06:17 AM - CJ conversion to M14 (jay reiter)
10. 06:52 AM - Re: CJ conversion to M14 (jay reiter)
11. 07:17 AM - Re: range (Brian Lloyd)
12. 07:35 AM - Re: Yak 50 help needed (Walt Fricke)
13. 07:35 AM - Re: CJ conversion to M14 (Brian Lloyd)
14. 07:43 AM - Re: range (Brian Lloyd)
15. 08:30 AM - Re: Yak 50 help needed (Yakjock)
16. 08:44 AM - Re: Yak 50 help needed (Gus Fraser)
17. 08:48 AM - Re: range (Gus Fraser)
18. 09:37 AM - Re: range (Brian Lloyd)
19. 09:47 AM - Re: Wildcat gone (Bill Halverson)
20. 11:12 AM - Re: Yak 50 help needed (Walt Fricke)
21. 11:15 AM - Re: Yak 50 help needed (Walt Fricke)
22. 12:17 PM - Phone recorder (Doug)
23. 12:42 PM - Re: Yak 50 help needed (Doug)
24. 02:21 PM - Re: range (Walt Lannon)
25. 06:15 PM - Carb heat?? (Dean Courtney)
26. 06:40 PM - MAP and RPM (was: range) (Brian Lloyd)
27. 06:40 PM - Re: range (Gus Fraser)
28. 07:36 PM - Jim Esposito (Jeff Linebaugh)
29. 07:38 PM - Request from the Smoking Section..... (Jeff Linebaugh)
30. 08:53 PM - Re: Spam Can? (Rick Basiliere)
Message 1
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--> Yak-List message posted by: "Mark Jefferies YAK UK Ltd" <mark@yakuk.com>
The 400hp uses 2lts/ hr more at the same a/c speed as a 360hp, this is due to the
impeller (more drag as it turns faster) taking the power I believe. Or was
it a less well "tuned engine" anyway the theory is correct :>))
> --> Yak-List message posted by: "Mark Jefferies YAK UK Ltd" <mark@yakuk.com>
>
> hi all, Brian has prompted me to write.....!!!
Actually that was aimed at Mark Schrick because we ended up landing at an airport
without fuel because the Yak-52 with the 400 hp engine was just using too much
fuel.
OTOH your posting was quite interesting so I am glad I prompted you to post.
Message 2
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| From: | "Jorgen Nielsen @ Mweb" <jorgen.nielsen@mweb.co.za> |
| Subject: | Re: FOD for thought... |
--> Yak-List message posted by: "Jorgen Nielsen @ Mweb" <jorgen.nielsen@mweb.co.za>
It can jam at the rear end of the fuselage as well. Where the cables attach
to the elevator control horns. You can get access to this via a panel on
LHS at rear, a few screws to take out, I did this last week and stuck my arm
in there, groping around to see if I could find any objects. A bright torch
and mirror will also let you inspect areas out of your reach.
I have decided I will do this periodically.
BTW, is there anywhere on the 'net a FAQ for the Yaks? There is often so
much good info posted here, it would be nice if there was a faq detailing
for example common air problems and their fixes, how to remove seats, etc.
etc.
Jorgen
Subject: Re: Yak-List: FOD for thought...
--> Yak-List message posted by: "gpa" <catfsh4u@bellsouth.net>
Do the FOD accidents in the Yak52's involve only the elevator bell crank
located behind the second seat or has there been jamming of the controls at
other locations as well?
Greg
Message 3
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| Subject: | Re: FOD for thought... |
--> Yak-List message posted by: "A. Dennis Savarese" <adsavar@gte.net>
Within approximately two to three weeks I will have a kit available which
will cover the rear most bulk head. As soon as it is available I will post
photos on my web site and on the Matronics site for all to see. I think
this will be an excellent safety item which should be installed in all 52's
regardless of model.
Fly safe
Dennis
----- Original Message -----
From: "gpa" <catfsh4u@bellsouth.net>
Subject: Re: Yak-List: FOD for thought...
> --> Yak-List message posted by: "gpa" <catfsh4u@bellsouth.net>
>
> Do the FOD accidents in the Yak52's involve only the elevator bell crank
> located behind the second seat or has there been jamming of the controls
at
> other locations as well?
>
> Greg
>
> ----- Original Message -----
> From: "Gus Fraser" <fraseg@comcast.net>
> To: <yak-list@matronics.com>
> Subject: RE: Yak-List: FOD for thought...
>
>
> > --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
> >
> > David,
> > Did you see my selection of posts last week on this subject. I am in the
> > progress, after speaking to Mark Jeffries, of fabricating a ceconite
patch
> > that will sit in the tailcone secured to the last frame before the mag
> flux
> > detector with wholes for the elevator and rudder cables. Mark has
patterns
> > for these which he has kindly offered to make available from his web
site
> > for you all to take a look at.
> >
> > I know of 4 instances of this. When I bought my aircraft I found a bit
of
> > sharp glass 6 inches by 3 inches UNDER MY SEAT. Imagine how bad that
could
> > have been during an outside maneuver.
> >
> > Thanks for posting that.
> >
> > Gus
> >
> > -----Original Message-----
> > From: owner-yak-list-server@matronics.com
> > [mailto:owner-yak-list-server@matronics.com]On Behalf Of Dave Laird
> > To: yak-list@matronics.com
> > Subject: Yak-List: FOD for thought...
> >
> >
> > --> Yak-List message posted by: Dave Laird <dave@davelaird.com>
> >
> > The following was in the EAA "e-hotline" today...
> >
> >
> > Yak-52 FOD Accidents Are a Warning to All
> > EAA Founder and Chairman Paul Poberezny recently received a letter from
> > National Transportation Safety Board Senior Air Safety Inspector Arnold
> > W. Scott telling about a spate of accidents around the world where
> > foreign object damage (FOD) has impaired or jammed the controls of the
> > Yak-52. The design is prone to this problem because the fuselage is
> > open behind the rear seat and the elevator control mechanism is close
> > to the fuselage floor. Many of the accidents have involved
> > fatalities, and aerobatics didnt seem to play a part in control
> > jamming caused by everything from an errant nut to an airsick bag and a
> > set of locking pliers. Scott urges Yak-52 owners to install some form
> > of barrier to protect the elevator bell crank from FOD jamming or to
> > install Plexiglas skin panels so they can inspect the mechanism before
> > flight.
> >
> > Paul said the Yak should stand as an example for all pilots and
> > aircraft owners regardless of what they fly, because no aircraft is
> > immune to the controls being jammed by FOD.
> >
> >
> > Dave Laird
> > CJ6A N63536 "Betty"
> > Dallas
> >
> >
>
>
Message 4
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--> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
I think that it is because of the increased air pressure. Due to this to
maintain the mixture there is more fuel needed to maintain the fuel air
ratio. But hey, at any given manifold pressure and a given RPM surely they
produce the same power and therefore the same fuel usage ? The PF engine is
only a 400 HP engine when it produces 400 HP.
Remember that any supercharged single stage, non boosted, non geared
supercharger pays a price when operating below a certain altitude for this
very reason. I can agree that below, say, 4000 the 400 HP is going to cost
more to run but up high at the same settings they should be about the same.
Superchargers have a critical altitude. This is where the power of the super
charger has the most benefit. Below this altitude it uses more fuel for the
reason stated above, above this altitude the supercharger is not as
effective because it can't thicken the air enough. On looking in the Yak
manual I found that there is specifically no critical altitude. Not sure why
this is but in my experiments with fuel flow and altitude I have found that
between 11,500 and 12,500 are best. Of course this is not to be done without
O2 for the weakest link in the chain, the pilot.
I think, rather than re-gearing the M14P it would be worth looking into a
second stage supercharger with a pressure limiting switch. What this would
do is switch in the second stage above a certain pressure altitude.
Therefore better altitude and better X-country performance without the
penalty of flying at lower altitudes.
Thoughts ???
I have a fantastic book which I got from a yard sale two years ago which was
written in 1943 by GM about this subject. Great book and written in stupid
person English, hence my understanding of the subject.
Great bit of history. It draws conclusions about Japanese engine design and
the reasons for the Zero being the way it is against US doctrine on engine
design. It stated that all engine design is a compromise to give the best
performance at a given altitude.
Hope this helps
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Mark Jefferies
YAK UK Ltd
Subject: Yak-List: range
--> Yak-List message posted by: "Mark Jefferies YAK UK Ltd" <mark@yakuk.com>
The 400hp uses 2lts/ hr more at the same a/c speed as a 360hp, this is due
to the impeller (more drag as it turns faster) taking the power I believe.
Or was it a less well "tuned engine" anyway the theory is correct :>))
> --> Yak-List message posted by: "Mark Jefferies YAK UK Ltd"
<mark@yakuk.com>
>
> hi all, Brian has prompted me to write.....!!!
Actually that was aimed at Mark Schrick because we ended up landing at an
airport
without fuel because the Yak-52 with the 400 hp engine was just using too
much
fuel.
OTOH your posting was quite interesting so I am glad I prompted you to post.
Message 5
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| Subject: | FOD for thought... |
--> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
Dennis,
Would you consider posting a pattern as this is a critical safety issue. As
for other aircraft, If the CJ has a hollow tail cone then this is as much an
issue for you guys as us with Yaks. Don't wait till 4 CJs go in to address
this problem.
Given the incidence of this event maybe the insurance guys could cut some
slack on those using an agreed pattern to make the patch ?
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of A. Dennis
Savarese
Subject: Re: Yak-List: FOD for thought...
--> Yak-List message posted by: "A. Dennis Savarese" <adsavar@gte.net>
Within approximately two to three weeks I will have a kit available which
will cover the rear most bulk head. As soon as it is available I will post
photos on my web site and on the Matronics site for all to see. I think
this will be an excellent safety item which should be installed in all 52's
regardless of model.
Fly safe
Dennis
----- Original Message -----
From: "gpa" <catfsh4u@bellsouth.net>
Subject: Re: Yak-List: FOD for thought...
> --> Yak-List message posted by: "gpa" <catfsh4u@bellsouth.net>
>
> Do the FOD accidents in the Yak52's involve only the elevator bell crank
> located behind the second seat or has there been jamming of the controls
at
> other locations as well?
>
> Greg
>
> ----- Original Message -----
> From: "Gus Fraser" <fraseg@comcast.net>
> To: <yak-list@matronics.com>
> Subject: RE: Yak-List: FOD for thought...
>
>
> > --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
> >
> > David,
> > Did you see my selection of posts last week on this subject. I am in the
> > progress, after speaking to Mark Jeffries, of fabricating a ceconite
patch
> > that will sit in the tailcone secured to the last frame before the mag
> flux
> > detector with wholes for the elevator and rudder cables. Mark has
patterns
> > for these which he has kindly offered to make available from his web
site
> > for you all to take a look at.
> >
> > I know of 4 instances of this. When I bought my aircraft I found a bit
of
> > sharp glass 6 inches by 3 inches UNDER MY SEAT. Imagine how bad that
could
> > have been during an outside maneuver.
> >
> > Thanks for posting that.
> >
> > Gus
> >
> > -----Original Message-----
> > From: owner-yak-list-server@matronics.com
> > [mailto:owner-yak-list-server@matronics.com]On Behalf Of Dave Laird
> > To: yak-list@matronics.com
> > Subject: Yak-List: FOD for thought...
> >
> >
> > --> Yak-List message posted by: Dave Laird <dave@davelaird.com>
> >
> > The following was in the EAA "e-hotline" today...
> >
> >
> > Yak-52 FOD Accidents Are a Warning to All
> > EAA Founder and Chairman Paul Poberezny recently received a letter from
> > National Transportation Safety Board Senior Air Safety Inspector Arnold
> > W. Scott telling about a spate of accidents around the world where
> > foreign object damage (FOD) has impaired or jammed the controls of the
> > Yak-52. The design is prone to this problem because the fuselage is
> > open behind the rear seat and the elevator control mechanism is close
> > to the fuselage floor. Many of the accidents have involved
> > fatalities, and aerobatics didnt seem to play a part in control
> > jamming caused by everything from an errant nut to an airsick bag and a
> > set of locking pliers. Scott urges Yak-52 owners to install some form
> > of barrier to protect the elevator bell crank from FOD jamming or to
> > install Plexiglas skin panels so they can inspect the mechanism before
> > flight.
> >
> > Paul said the Yak should stand as an example for all pilots and
> > aircraft owners regardless of what they fly, because no aircraft is
> > immune to the controls being jammed by FOD.
> >
> >
> > Dave Laird
> > CJ6A N63536 "Betty"
> > Dallas
> >
> >
>
>
Message 6
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| Subject: | Yak 50 help needed |
--> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
Walt.
Is there anyway you could upgrade to a Yak 52TW trailer ?
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Fricke
Subject: Yak-List: Yak 50 help needed
--> Yak-List message posted by: Walt Fricke <walterfricke@yahoo.com>
My yak 50 has developed a pretty awesome tailwheel shimmy and it looks as
though the yoke is worn out. Anyone have any insights, parts, ideas?
---------------------------------
Message 7
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| Subject: | Re: FOD for thought... |
--> Yak-List message posted by: "A. Dennis Savarese" <adsavar@gte.net>
I'm going to make it available as an inexpensive kit. First I have to find
out the cost of the materials etc. Stay tuned. Then everyone can make
their own decision.
Dennis
----- Original Message -----
From: "Gus Fraser" <fraseg@comcast.net>
Subject: RE: Yak-List: FOD for thought...
> --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
>
> Dennis,
> Would you consider posting a pattern as this is a critical safety issue.
As
> for other aircraft, If the CJ has a hollow tail cone then this is as much
an
> issue for you guys as us with Yaks. Don't wait till 4 CJs go in to address
> this problem.
>
> Given the incidence of this event maybe the insurance guys could cut some
> slack on those using an agreed pattern to make the patch ?
>
> Gus
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com]On Behalf Of A. Dennis
> Savarese
> To: yak-list@matronics.com
> Subject: Re: Yak-List: FOD for thought...
>
>
> --> Yak-List message posted by: "A. Dennis Savarese" <adsavar@gte.net>
>
> Within approximately two to three weeks I will have a kit available which
> will cover the rear most bulk head. As soon as it is available I will
post
> photos on my web site and on the Matronics site for all to see. I think
> this will be an excellent safety item which should be installed in all
52's
> regardless of model.
> Fly safe
> Dennis
>
>
> ----- Original Message -----
> From: "gpa" <catfsh4u@bellsouth.net>
> To: <yak-list@matronics.com>
> Subject: Re: Yak-List: FOD for thought...
>
>
> > --> Yak-List message posted by: "gpa" <catfsh4u@bellsouth.net>
> >
> > Do the FOD accidents in the Yak52's involve only the elevator bell crank
> > located behind the second seat or has there been jamming of the controls
> at
> > other locations as well?
> >
> > Greg
> >
> > ----- Original Message -----
> > From: "Gus Fraser" <fraseg@comcast.net>
> > To: <yak-list@matronics.com>
> > Subject: RE: Yak-List: FOD for thought...
> >
> >
> > > --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
> > >
> > > David,
> > > Did you see my selection of posts last week on this subject. I am in
the
> > > progress, after speaking to Mark Jeffries, of fabricating a ceconite
> patch
> > > that will sit in the tailcone secured to the last frame before the mag
> > flux
> > > detector with wholes for the elevator and rudder cables. Mark has
> patterns
> > > for these which he has kindly offered to make available from his web
> site
> > > for you all to take a look at.
> > >
> > > I know of 4 instances of this. When I bought my aircraft I found a bit
> of
> > > sharp glass 6 inches by 3 inches UNDER MY SEAT. Imagine how bad that
> could
> > > have been during an outside maneuver.
> > >
> > > Thanks for posting that.
> > >
> > > Gus
> > >
> > > -----Original Message-----
> > > From: owner-yak-list-server@matronics.com
> > > [mailto:owner-yak-list-server@matronics.com]On Behalf Of Dave Laird
> > > To: yak-list@matronics.com
> > > Subject: Yak-List: FOD for thought...
> > >
> > >
> > > --> Yak-List message posted by: Dave Laird <dave@davelaird.com>
> > >
> > > The following was in the EAA "e-hotline" today...
> > >
> > >
> > > Yak-52 FOD Accidents Are a Warning to All
> > > EAA Founder and Chairman Paul Poberezny recently received a letter
from
> > > National Transportation Safety Board Senior Air Safety Inspector
Arnold
> > > W. Scott telling about a spate of accidents around the world where
> > > foreign object damage (FOD) has impaired or jammed the controls of the
> > > Yak-52. The design is prone to this problem because the fuselage is
> > > open behind the rear seat and the elevator control mechanism is close
> > > to the fuselage floor. Many of the accidents have involved
> > > fatalities, and aerobatics didnt seem to play a part in control
> > > jamming caused by everything from an errant nut to an airsick bag and
a
> > > set of locking pliers. Scott urges Yak-52 owners to install some form
> > > of barrier to protect the elevator bell crank from FOD jamming or to
> > > install Plexiglas skin panels so they can inspect the mechanism before
> > > flight.
> > >
> > > Paul said the Yak should stand as an example for all pilots and
> > > aircraft owners regardless of what they fly, because no aircraft is
> > > immune to the controls being jammed by FOD.
> > >
> > >
> > > Dave Laird
> > > CJ6A N63536 "Betty"
> > > Dallas
> > >
> > >
> >
> >
>
>
Message 8
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--> Yak-List message posted by: cjpilot710@aol.com
The CAF lost their Wildcat yesterday.
Went down on approach into Elliington airport in TX.
Pilot killed, aircraft destroyed.
Jim Goolsby
"They that can give up essential liberty to obtain a little safety,
deserve neither liberty nor safety"
Benjamin Franklin 1759
"With my shield, or on it"
Trojan Warriors BC
"The reason older men are like fine wine. When young, they are like grapes
until some woman stomps all over them."
Unknown older man.
Message 9
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| Subject: | CJ conversion to M14 |
--> Yak-List message posted by: "jay reiter" <jmreiter@adelphia.net>
Just got back from Hayward California. Gary Strehle is working on a CJ project
that was taken apart by someone else. I was able to help him with the pneumatic
system and some odds and ends.
I have some questions:
How do you handle the oil temp on M14 the sensor is on the other side of the engine?
Fabricate a different line or switch the shovel?
What regulator do you use for the small Alternator I think it was a B&C I did not
write down the name.
Message 10
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| Subject: | Re: CJ conversion to M14 |
--> Yak-List message posted by: "jay reiter" <jmreiter@adelphia.net>
Actualy My oil question should have been how do you handle the oil out to
the cooler.
Message 11
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--> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
Gus Fraser wrote:
> --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
>
> I think that it is because of the increased air pressure. Due to this
> to maintain the mixture there is more fuel needed to maintain the
> fuel air ratio. But hey, at any given manifold pressure and a given
> RPM surely they produce the same power and therefore the same fuel
> usage ? The PF engine is only a 400 HP engine when it produces 400
> HP.
But Mark is correct in that the supercharger is geared to a higher RPM for a given
crankshaft RPM therefore it requires more power to drive. When the output
shaft is delivering the same HP to the prop the 400 hp engine is still using
more fuel because there is greater hp consumed in the supercharger.
> Remember that any supercharged single stage, non boosted, non geared
> supercharger
Huh? If it has a supercharger, it is boosted.
> Superchargers have a critical altitude. This is where the power of
> the super charger has the most benefit.
First, let's get our terms straight so we make sure we are speaking of apples and
apples. When I see the term "supercharger" I think of a device that takes
power from the crankshaft to power a compressor that will increase manifold pressure.
When I see the term "turbocharger" I think of a device that uses waste
power in the exhaust to turn a turbine which in turn drives a compressor to
increase manifold pressure.
Turbochargers that are powered by exhaust gas do indeed have a critical altitude
above which the engine cannot sustain maximum usable manifold pressure. In
an engine with an automatic or adjustable waste gate, it is the altitude at which
the waste gate is all the way closed and the turbocharger is providing maximum
boost. If you continue to climb above this altitude, MAP will decrease just
as it does with a normally aspirated engine.
A mechanical supercharger, one that is gear-driven from the crankshaft, always
provides a fixed amount of boost, the amount of which is totally dependent on
engine RPM. For instance, the supercharger in the stock CJ6A engine provides
85 mm-Hg of boost at 2350 RPM but only 80 mm-Hg of boost at 2250 RPM. Since all
of this boost is usable, there is no critical altitude.
In bigger engines with superchargers the boost available down low may be greater
than needed to achieve maximum usable MAP. (This also varies with grade of
fuel.) I presume this is what you mean by operating below critical altitude,
that being the altitude at which you can achieve maximum usable MAP at full throttle.
I guess we can consider this a critical altitude but I believe this is
a misnomer as we are not dealing with a turbocharger. Regardless, your point
is well taken. The engine is less efficient below the altitude where you can
run full throttle.
OTOH, most of us learned on flat engines, either normally aspirated or turbocharged,
not round engines. (There are some airplanes that use supercharged engines,
the Twin Bonanza and the Aero Commander 680 come to mind here, but I leave
them out of this discussion.) Their use of MAP and RPM is very different.
Those engines tend to keep MAP constant as the RPM is decreased. (MAP increases
slightly as RPM is decreased in a normally aspirated engine and stays constant
in a turbocharged engine below critical altitude.)
But a round engine with a supercharger gives you TWO controls to vary MAP: throttle
*and* RPM. Hal recently posted a message about landing a Sea Fury with the
throttle stuck full open. Did anyone notice that just by pulling the prop
(RPM) way back the pilot reduced his MAP to 30"Hg? If one is interested in efficient
operation, one should plan to run with the throttle wide and vary power
using the prop control. The instrumentation in the Yak already implies this
by calibrating the tachometer (RPM) in percent-of-power instead of RPM. The
implication is that it is OK to run at 50% or 60% of maximum RPM.
> Below this altitude it uses more fuel for the reason stated above,
> above this altitude the supercharger is not as effective because it
> can't thicken the air enough.
Well, it is still fully effective but it can only provide so much boost and if
you start with lower ambient/inlet pressure, you get lower final/outlet pressure.
> On looking in the Yak manual I found that there is specifically no
> critical altitude. Not sure why this is
There are two reasons for this:
1. it is a mechanical supercharger, not a turbocharger and;
2. full boost is allowable at sea-level.
You can leave the prop and throttle full-forward as you climb out and the MAP will
decrease with altitude just like a normally aspirated engine.
> but in my experiments with fuel flow and altitude I have found that
> between 11,500 and 12,500 are best. Of course this is not to be done
> without O2 for the weakest link in the chain, the pilot.
I have also found the most efficient altitude for the CJ6A to be around 11,000'.
As for O2, that is a function of the individual. The only way to know for
sure whether you need O2 at 12,500 is to use a pulse-oximeter to measure the O2
content in your blood. When I was younger and lived at 7,000' in Colorado I
found that I was fine for long periods at 14,500. I suffered none of the effects
of hypoxia at that altitude. Now I am not comfortable for any length of
time at 12,500 without O2.
> I think, rather than re-gearing the M14P it would be worth looking
> into a second stage supercharger with a pressure limiting switch.
> What this would do is switch in the second stage above a certain
> pressure altitude. Therefore better altitude and better X-country
> performance without the penalty of flying at lower altitudes.
Since the supercharger is geared to the engine anyway that is pretty hard to do
without total redesign of the engine. OTOH, it would be possible to effectively
create a second stage by adding a turbocharger. I believe that was done in
the B-17 and P-38 so there is prior art to adding turbochargers to supercharged
round engines.
> I have a fantastic book which I got from a yard sale two years ago
> which was written in 1943 by GM about this subject. Great book and
> written in stupid person English, hence my understanding of the
> subject. Great bit of history. It draws conclusions about Japanese
> engine design and the reasons for the Zero being the way it is
> against US doctrine on engine design. It stated that all engine
> design is a compromise to give the best performance at a given
> altitude.
You are certainly correct on that. Every engine is a compromise for operating
conditions. Still, if we know how the engine works, it is a fairly straight-forward
path to determining what is likely to be most efficient.
--
Brian Lloyd 6501 Red Hook Plaza, Suite 201
brian@lloyd.com St. Thomas, VI 00802
+1.340.998.9447 - voice +1.360.838.9669 - fax
GMT-4
Message 12
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| Subject: | Yak 50 help needed |
--> Yak-List message posted by: Walt Fricke <walterfricke@yahoo.com>
Are you saying upgrade to a 52TW airplane or a 52 TW tailwheel assembly?
Gus Fraser <fraseg@comcast.net> wrote:--> Yak-List message posted by: "Gus Fraser"
Walt.
Is there anyway you could upgrade to a Yak 52TW trailer ?
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Fricke
Subject: Yak-List: Yak 50 help needed
--> Yak-List message posted by: Walt Fricke
My yak 50 has developed a pretty awesome tailwheel shimmy and it looks as
though the yoke is worn out. Anyone have any insights, parts, ideas?
---------------------------------
---------------------------------
Message 13
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| Subject: | Re: CJ conversion to M14 |
--> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
jay reiter wrote:
> --> Yak-List message posted by: "jay reiter" <jmreiter@adelphia.net>
>
> Just got back from Hayward California. Gary Strehle is working on a
> CJ project that was taken apart by someone else. I was able to help
> him with the pneumatic system and some odds and ends. I have some
> questions:
>
> How do you handle the oil temp on M14 the sensor is on the other side
> of the engine? Fabricate a different line or switch the shovel?
Splice the wiring. In my case I just threw away the old chinese wiring and started
from scratch.
> What regulator do you use for the small Alternator I think it was a
> B&C I did not write down the name.
It probably was B&C. B&C has their own linear regulator/alternator controller
for their alternator. It is a very nice and reliable design with excellent regulation,
over voltage protection, AND battery temperature compensation. You
can get more information at:
http://www.bandcspecialty.com/
I have dealt with Bill Bainbridge and I think he is one of the best people to work
with in the industry. He was very ill-used by the FAA during the height of
their "let's abuse our power" period a few years back. I am glad he has remained
in business to produce top-quality products in spite of the FAA trying to
pull a Bob Hoover on him.
--
Brian Lloyd 6501 Red Hook Plaza, Suite 201
brian@lloyd.com St. Thomas, VI 00802
+1.340.998.9447 - voice +1.360.838.9669 - fax
GMT-4
Message 14
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--> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
Mark Jefferies YAK UK Ltd wrote:
> --> Yak-List message posted by: "Mark Jefferies YAK UK Ltd"
> <mark@yakuk.com>
>
> The 400hp uses 2lts/ hr more at the same a/c speed as a 360hp, this
> is due to the impeller (more drag as it turns faster) taking the
> power I believe. Or was it a less well "tuned engine" anyway the
> theory is correct :>))
Yes, that is true. However, a Yak-52 with stock fuel (what Mark had after the
fuel transfer pump for the aux tank failed) is already short legged. In flying
back from OSH to Northern California you have to cross some pretty uninhabited
territory. Airports are few and far between. When all you you can do is 150-175
nm legs you have to plan very carefully. And when the headwinds pick up
unexpectedly, what appears to be an ample fuel capacity margin can be eroded
to nothing very quickly.
The solution is to set alternate airports for the hop on both sides of the desired
destination. If you have favorable winds and have pulled the power back in
order to conserve fuel, you may make your hop to the farther airport. OTOH,
if you are feeling uncomfortable, you have already planned for a short hop, just
in case.
Because of the limited fuel capacity of the Yak-52 and the CJ6A, if you plan to
fly cross-country it is *critical* that you know the accuracy of your fuel gauges
and the expected fuel burn for a given power setting. You may need to make
some shorter cross-country flights to check out the fuel burn.
Also, at some point in time drain all the fuel out of the tanks and fill them up
say 5 liters at a time while checking the fuel gauge. First, you will find
out the real capacity of your tanks and, second, you will find out the accuracy
of your gauge. A good fuel totalizer is nice (there are some inexpensive ones
for boats that will work very nicely in a Yak/CJ) but contamination or a fuel
leak may cause the totalizer to give erroneous readings. Measuring the level
in the tank is the only sure way to know how much fuel you have left in the
airplane.
--
Brian Lloyd 6501 Red Hook Plaza, Suite 201
brian@lloyd.com St. Thomas, VI 00802
+1.340.998.9447 - voice +1.360.838.9669 - fax
GMT-4
Message 15
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| Subject: | Re: Yak 50 help needed |
--> Yak-List message posted by: "Yakjock" <Yakjock@msn.com>
Perhaps if you landed on the mains first???
Hal Morley
CJ-6A "8"
(503) 704-6559 cell
Message 16
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| Subject: | Yak 50 help needed |
--> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
Just the wheel for now :)
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Fricke
Subject: RE: Yak-List: Yak 50 help needed
--> Yak-List message posted by: Walt Fricke <walterfricke@yahoo.com>
Are you saying upgrade to a 52TW airplane or a 52 TW tailwheel assembly?
Gus Fraser <fraseg@comcast.net> wrote:--> Yak-List message posted by: "Gus
Fraser"
Walt.
Is there anyway you could upgrade to a Yak 52TW trailer ?
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Fricke
Subject: Yak-List: Yak 50 help needed
--> Yak-List message posted by: Walt Fricke
My yak 50 has developed a pretty awesome tailwheel shimmy and it looks as
though the yoke is worn out. Anyone have any insights, parts, ideas?
---------------------------------
---------------------------------
Message 17
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--> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
Brian,
I have a JPI fuel scan 450 and it is so accurate that to within 1/10 gal I
know what the refuel will be and I am sure that that is down to the person
who fills it. When I do it at my home field it just works on the nail. Have
you ever noticed that the fuel guy will always stop short of full tanks.
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Brian Lloyd
Subject: Re: Yak-List: range
--> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
Mark Jefferies YAK UK Ltd wrote:
> --> Yak-List message posted by: "Mark Jefferies YAK UK Ltd"
> <mark@yakuk.com>
>
> The 400hp uses 2lts/ hr more at the same a/c speed as a 360hp, this
> is due to the impeller (more drag as it turns faster) taking the
> power I believe. Or was it a less well "tuned engine" anyway the
> theory is correct :>))
Yes, that is true. However, a Yak-52 with stock fuel (what Mark had after
the fuel transfer pump for the aux tank failed) is already short legged. In
flying back from OSH to Northern California you have to cross some pretty
uninhabited territory. Airports are few and far between. When all you you
can do is 150-175 nm legs you have to plan very carefully. And when the
headwinds pick up unexpectedly, what appears to be an ample fuel capacity
margin can be eroded to nothing very quickly.
The solution is to set alternate airports for the hop on both sides of the
desired destination. If you have favorable winds and have pulled the power
back in order to conserve fuel, you may make your hop to the farther
airport. OTOH, if you are feeling uncomfortable, you have already planned
for a short hop, just in case.
Because of the limited fuel capacity of the Yak-52 and the CJ6A, if you plan
to fly cross-country it is *critical* that you know the accuracy of your
fuel gauges and the expected fuel burn for a given power setting. You may
need to make some shorter cross-country flights to check out the fuel burn.
Also, at some point in time drain all the fuel out of the tanks and fill
them up say 5 liters at a time while checking the fuel gauge. First, you
will find out the real capacity of your tanks and, second, you will find out
the accuracy of your gauge. A good fuel totalizer is nice (there are some
inexpensive ones for boats that will work very nicely in a Yak/CJ) but
contamination or a fuel leak may cause the totalizer to give erroneous
readings. Measuring the level in the tank is the only sure way to know how
much fuel you have left in the airplane.
--
Brian Lloyd 6501 Red Hook Plaza, Suite 201
brian@lloyd.com St. Thomas, VI 00802
+1.340.998.9447 - voice +1.360.838.9669 - fax
GMT-4
Message 18
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--> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
Gus Fraser wrote:
> --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
>
> Brian,
> I have a JPI fuel scan 450 and it is so accurate that to within 1/10 gal I
> know what the refuel will be and I am sure that that is down to the person
> who fills it. When I do it at my home field it just works on the nail. Have
> you ever noticed that the fuel guy will always stop short of full tanks.
They are very accurate and a really useful tool. But when there is a leak in the
system the totalizer may not tell the whole story. I had a fuel cap that didn't
seal properly when I checked the fuel levels during preflight in my Comanche.
The fuel was venting overboard unbeknownst to me because the cover on the
wing was preventing me from seeing it. A totalizer would not have told me
anything but the rapidly moving fuel gauge did. I made a precautionary landing
and discovered the problem. If I had relied on a totalizer I would have become
a fuel-exhaustion "incident".
Totalizers are nice. Tank gauges are necessary.
--
Brian Lloyd 6501 Red Hook Plaza, Suite 201
brian@lloyd.com St. Thomas, VI 00802
+1.340.998.9447 - voice +1.360.838.9669 - fax
GMT-4
Message 19
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| Subject: | Re: Wildcat gone |
--> Yak-List message posted by: Bill Halverson <william@netpros.net>
My God how sad ... how depressing ... any idea what happened?
Bill Halverson
At 06:01 AM 10/19/2003, you wrote:
>--> Yak-List message posted by: cjpilot710@aol.com
>
>
>The CAF lost their Wildcat yesterday.
>Went down on approach into Elliington airport in TX.
>Pilot killed, aircraft destroyed.
>
>Jim Goolsby
Message 20
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| Subject: | Re: Yak 50 help needed |
--> Yak-List message posted by: Walt Fricke <walterfricke@yahoo.com>
Thanks Hal. I think that is the problem. I've started doing wheel landings.
Since the T/W lock is interconnected to the stick (it locks with the stick all
the way back) I've been landing with it "unlocked" and perhaps it is off center
due to the EXTREME TORQUE encountered on takeoff. :-) So wheel landings (a
new habit picked up after being spoiled by the view out the front of the Staggerwing)
actually may be the problem. If the TW is not locked when the tailwheel
touches down, the shimmy keeps if from locking (pin drips in to the perfectly
alligned hole). I need to go back to full stall landings. Seems I'm not
the only Yak 50 with the T/W shimmy.
Yakjock <Yakjock@msn.com> wrote:--> Yak-List message posted by: "Yakjock"
Perhaps if you landed on the mains first???
Hal Morley
CJ-6A "8"
(503) 704-6559 cell
---------------------------------
Message 21
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| Subject: | Yak 50 help needed |
--> Yak-List message posted by: Walt Fricke <walterfricke@yahoo.com>
While it may be possible, I would hate to move the wheel that far aft (for asthetic
purposes.)
Gus Fraser <fraseg@comcast.net> wrote:--> Yak-List message posted by: "Gus Fraser"
Just the wheel for now :)
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Fricke
Subject: RE: Yak-List: Yak 50 help needed
--> Yak-List message posted by: Walt Fricke
Are you saying upgrade to a 52TW airplane or a 52 TW tailwheel assembly?
Gus Fraser wrote:--> Yak-List message posted by: "Gus
Fraser"
Walt.
Is there anyway you could upgrade to a Yak 52TW trailer ?
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Fricke
Subject: Yak-List: Yak 50 help needed
--> Yak-List message posted by: Walt Fricke
My yak 50 has developed a pretty awesome tailwheel shimmy and it looks as
though the yoke is worn out. Anyone have any insights, parts, ideas?
---------------------------------
---------------------------------
---------------------------------
Message 22
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--> Yak-List message posted by: "Doug" <rvfltd@televar.com>
To all those who tried to leave me a message between Oct 13th and today, please
try again during business hours or contact me by email as my business line seems
to have gremlins in it or my brand new digital answering machine is TU. You
could also try me at 509-826-4047
Always yakin,
Doug Sapp
Message 23
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| Subject: | Re: Yak 50 help needed |
--> Yak-List message posted by: "Doug" <rvfltd@televar.com>
Walt,
The system sounds the same as in my yak 18. It has a Bowden cable connected
to the elevator horn. The cable connects to the top of the tail wheel
assembly with a cap nut under the cap nut the cable has a spring in it which
pushed a case hardened pin into the tail wheel to lock it, Check the
spring, clean everything, and re lube with white lithium grease to make
things move a bit better. I had to add a 2nd spring to mine to make it lock
in a more positive manner. Once I cleaned, lubed and added a second spring
it was been great.
Always yakin,
Doug (the little wheel is on the right end) Sapp
----- Original Message -----
From: "Walt Fricke" <walterfricke@yahoo.com>
Subject: Re: Yak-List: Yak 50 help needed
> --> Yak-List message posted by: Walt Fricke <walterfricke@yahoo.com>
>
> Thanks Hal. I think that is the problem. I've started doing wheel
landings. Since the T/W lock is interconnected to the stick (it locks with
the stick all the way back) I've been landing with it "unlocked" and perhaps
it is off center due to the EXTREME TORQUE encountered on takeoff. :-) So
wheel landings (a new habit picked up after being spoiled by the view out
the front of the Staggerwing) actually may be the problem. If the TW is not
locked when the tailwheel touches down, the shimmy keeps if from locking
(pin drips in to the perfectly alligned hole). I need to go back to full
stall landings. Seems I'm not the only Yak 50 with the T/W shimmy.
>
> Yakjock <Yakjock@msn.com> wrote:--> Yak-List message posted by: "Yakjock"
>
> Perhaps if you landed on the mains first???
>
> Hal Morley
> CJ-6A "8"
>
> (503) 704-6559 cell
>
>
> ---------------------------------
>
>
Message 24
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--> Yak-List message posted by: "Walt Lannon" <lannon@look.ca>
More on superchargers, I see a few misconceptions in the previous
posts; ---------
A supercharger is a device designed to increase engine manifold pressure and
therefore increase output horsepower.
The term generally refers to an internal engine driven centrifugal blower. A
turbocharger is an externally driven supercharger, driven by exhaust gases.
It could be driven by some other power source and have another name but it
would
still be a supercharger.
All supercharged engines regardless of boost source are technically
"altitude" engines and have a critical altitude. In the case of the Huosai,
M14P, AI14R, etc. the critical altitude happens to be sea level so it
becomes a moot point unless you were operating from below that level. A
normally aspirated engine has no critical altitude; ie: full throttle can be
applied at any altitude assuming RPM and fuel mixture are correct.
The critical altitude may be defined as the altitude at which full throttle
operation will not exceed the engines design rated (ie: maximum continuous)
power.
All other supercharged engines that I am aware of have a critical altitude
at some point above sea level. This is true also of a waste gated system,
the pilot may be able to apply full throttle for take-off and climb with the
waste gate automatically controlling the MAP. Upon reaching the critical
altitude the waste gate will be closed.
For example the P&W R1340 rated at 550 HP max. cont. at 32.5 in. and 2200
RPM can maintain that power to 5500 ft. in standard air with the 10:1
blower. The critical altitude of the12:1 blower model is approx. 7000 ft.
Above these points the MAP will decrease like a normally aspirated engine.
This is a simple single stage, single speed blower. There are much more
complex designs, some with turbochargers as well that can increase the
crit.alt. dramatically.
The suggestion that "one should run with the throttle wide and vary power
with the prop control" is not good advice. The fact that Bud Granley was
able to reduce power in the Sea Fury in this manner in no way recommends
this procedure for the engines we are operating. It is entirely possible
that the R4360 in this case is equipped with automatic devices sensing MAP
and RPM and controlling a waste gate.
You may get away with that practice for a little while with the Huosai, M14P
etc. but you will eventually fail the engine. With a truly supercharged
engine you could destroy it in a matter of minutes.
Just as a matter of interest (and maybe generate a little controversy) the
blower is the reason the T6/Harvard runs away from the CJ6 (Huosai or M14)
above 6000 ft or so.
Cheers;
Walt
----- Original Message -----
From: "Brian Lloyd" <brian@lloyd.com>
Subject: Re: Yak-List: range
> --> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
>
> Gus Fraser wrote:
>
> > --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
> >
> > I think that it is because of the increased air pressure. Due to this
> > to maintain the mixture there is more fuel needed to maintain the
> > fuel air ratio. But hey, at any given manifold pressure and a given
> > RPM surely they produce the same power and therefore the same fuel
> > usage ? The PF engine is only a 400 HP engine when it produces 400
> > HP.
>
> But Mark is correct in that the supercharger is geared to a higher RPM for
a given crankshaft RPM therefore it requires more power to drive. When the
output shaft is delivering the same HP to the prop the 400 hp engine is
still using more fuel because there is greater hp consumed in the
supercharger.
>
> > Remember that any supercharged single stage, non boosted, non geared
> > supercharger
>
> Huh? If it has a supercharger, it is boosted.
>
> > Superchargers have a critical altitude. This is where the power of
> > the super charger has the most benefit.
>
> First, let's get our terms straight so we make sure we are speaking of
apples and apples. When I see the term "supercharger" I think of a device
that takes power from the crankshaft to power a compressor that will
increase manifold pressure. When I see the term "turbocharger" I think of a
device that uses waste power in the exhaust to turn a turbine which in turn
drives a compressor to increase manifold pressure.
>
> Turbochargers that are powered by exhaust gas do indeed have a critical
altitude above which the engine cannot sustain maximum usable manifold
pressure. In an engine with an automatic or adjustable waste gate, it is
the altitude at which the waste gate is all the way closed and the
turbocharger is providing maximum boost. If you continue to climb above
this altitude, MAP will decrease just as it does with a normally aspirated
engine.
>
> A mechanical supercharger, one that is gear-driven from the crankshaft,
always provides a fixed amount of boost, the amount of which is totally
dependent on engine RPM. For instance, the supercharger in the stock CJ6A
engine provides 85 mm-Hg of boost at 2350 RPM but only 80 mm-Hg of boost at
2250 RPM. Since all of this boost is usable, there is no critical altitude.
>
> In bigger engines with superchargers the boost available down low may be
greater than needed to achieve maximum usable MAP. (This also varies with
grade of fuel.) I presume this is what you mean by operating below critical
altitude, that being the altitude at which you can achieve maximum usable
MAP at full throttle. I guess we can consider this a critical altitude but
I believe this is a misnomer as we are not dealing with a turbocharger.
Regardless, your point is well taken. The engine is less efficient below
the altitude where you can run full throttle.
>
> OTOH, most of us learned on flat engines, either normally aspirated or
turbocharged, not round engines. (There are some airplanes that use
supercharged engines, the Twin Bonanza and the Aero Commander 680 come to
mind here, but I leave them out of this discussion.) Their use of MAP and
RPM is very different. Those engines tend to keep MAP constant as the RPM
is decreased. (MAP increases slightly as RPM is decreased in a normally
aspirated engine and stays constant in a turbocharged engine below critical
altitude.)
>
> But a round engine with a supercharger gives you TWO controls to vary MAP:
throttle *and* RPM. Hal recently posted a message about landing a Sea Fury
with the throttle stuck full open. Did anyone notice that just by pulling
the prop (RPM) way back the pilot reduced his MAP to 30"Hg? If one is
interested in efficient operation, one should plan to run with the throttle
wide and vary power using the prop control. The instrumentation in the Yak
already implies this by calibrating the tachometer (RPM) in percent-of-power
instead of RPM. The implication is that it is OK to run at 50% or 60% of
maximum RPM.
>
> > Below this altitude it uses more fuel for the reason stated above,
> > above this altitude the supercharger is not as effective because it
> > can't thicken the air enough.
>
> Well, it is still fully effective but it can only provide so much boost
and if you start with lower ambient/inlet pressure, you get lower
final/outlet pressure.
>
> > On looking in the Yak manual I found that there is specifically no
> > critical altitude. Not sure why this is
>
> There are two reasons for this:
>
> 1. it is a mechanical supercharger, not a turbocharger and;
>
> 2. full boost is allowable at sea-level.
>
> You can leave the prop and throttle full-forward as you climb out and the
MAP will decrease with altitude just like a normally aspirated engine.
>
> > but in my experiments with fuel flow and altitude I have found that
> > between 11,500 and 12,500 are best. Of course this is not to be done
> > without O2 for the weakest link in the chain, the pilot.
>
> I have also found the most efficient altitude for the CJ6A to be around
11,000'. As for O2, that is a function of the individual. The only way to
know for sure whether you need O2 at 12,500 is to use a pulse-oximeter to
measure the O2 content in your blood. When I was younger and lived at
7,000' in Colorado I found that I was fine for long periods at 14,500. I
suffered none of the effects of hypoxia at that altitude. Now I am not
comfortable for any length of time at 12,500 without O2.
>
> > I think, rather than re-gearing the M14P it would be worth looking
> > into a second stage supercharger with a pressure limiting switch.
> > What this would do is switch in the second stage above a certain
> > pressure altitude. Therefore better altitude and better X-country
> > performance without the penalty of flying at lower altitudes.
>
> Since the supercharger is geared to the engine anyway that is pretty hard
to do without total redesign of the engine. OTOH, it would be possible to
effectively create a second stage by adding a turbocharger. I believe that
was done in the B-17 and P-38 so there is prior art to adding turbochargers
to supercharged round engines.
>
> > I have a fantastic book which I got from a yard sale two years ago
> > which was written in 1943 by GM about this subject. Great book and
> > written in stupid person English, hence my understanding of the
> > subject. Great bit of history. It draws conclusions about Japanese
> > engine design and the reasons for the Zero being the way it is
> > against US doctrine on engine design. It stated that all engine
> > design is a compromise to give the best performance at a given
> > altitude.
>
> You are certainly correct on that. Every engine is a compromise for
operating conditions. Still, if we know how the engine works, it is a
fairly straight-forward path to determining what is likely to be most
efficient.
>
> --
>
> Brian Lloyd 6501 Red Hook Plaza, Suite 201
> brian@lloyd.com St. Thomas, VI 00802
> +1.340.998.9447 - voice +1.360.838.9669 - fax
> GMT-4
>
>
Message 25
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--> Yak-List message posted by: "Dean Courtney" <deancourtney696@hotmail.com>
Yakers,
Any and all thoughts on the carb heat system on a Yak 50/52, or any M14
powered bird?
Most 50's I have seen DO NOT have carb heat, in discussions with some Suhkio
owners they say their nice new aircraft DO NOT have carb heat at all.
I am considering building a nice intake scoop for the 50, and canning all
the broken junk in my carb heat box. Just not sure about "out smarting" the
manufacturer, they put it on for a reason? Now they don't on the Suhkio? Did
it ever need it? OPINIONS PLEASE............
Thanks,
Dean Courtney
Yak 50 84-2805
deancourtney696@hotmail.com
Never get a busy signal because you are always connected with high-speed
Internet access. Click here to comparison-shop providers.
https://broadband.msn.com
Message 26
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| Subject: | MAP and RPM (was: range) |
--> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
Walt Lannon wrote:
> A supercharger is a device designed to increase engine manifold
> pressure and therefore increase output horsepower. The term generally
> refers to an internal engine driven centrifugal blower. A
> turbocharger is an externally driven supercharger, driven by exhaust
> gases. It could be driven by some other power source and have another
> name but it would still be a supercharger.
Yes, I know. I will take care to be even more specific, exact, and detailed in
my next post.
BTW, you can also have a vane-type "Roots" supercharger as well. I don't recall
if I have seen any of those on aircraft engines but it is not beyond the realm
of reason.
> All supercharged engines regardless of boost source are technically
> "altitude" engines and have a critical altitude. In the case of the
> Huosai, M14P, AI14R, etc. the critical altitude happens to be sea
> level so it becomes a moot point unless you were operating from below
> that level.
It is still a moot point because the specification for maximum MAP is ambient pressure
plus 85mm-Hg so you can still use full boost below sea level.
> normally aspirated engine has no critical altitude; ie: full throttle
> can be applied at any altitude assuming RPM and fuel mixture are
> correct.
>
> The critical altitude may be defined as the altitude at which full
> throttle operation will not exceed the engines design rated (ie:
> maximum continuous) power.
I think I would define it slightly differently. Critical altitude is the altitude
that maximum available boost does not exceed maximum specified MAP for conditions.
Critical altitude may be different for TO, METO, and max continuous
power. For some engines it will also change with fuel octane ratings and RPM.
> All other supercharged engines that I am aware of have a critical
> altitude at some point above sea level. This is true also of a waste
> gated system, the pilot may be able to apply full throttle for
> take-off and climb with the waste gate automatically controlling the
> MAP. Upon reaching the critical altitude the waste gate will be
> closed.
Correct.
> For example the P&W R1340 rated at 550 HP max. cont. at 32.5 in. and
> 2200 RPM can maintain that power to 5500 ft. in standard air with the
> 10:1 blower. The critical altitude of the 12:1 blower model is
> approx. 7000 ft. Above these points the MAP will decrease like a
> normally aspirated engine.
Well actually, if you leave the throttle alone, the MAP will decrease with altitude
anyway. But you are allowed to continue opening the throttle in order to
maintain that 32.5 in-Hg MAP since the "blower" has excess boost.
> This is a simple single stage, single speed blower. There are much
> more complex designs, some with turbochargers as well that can
> increase the crit.alt. dramatically.
Yes.
> The suggestion that "one should run with the throttle wide and vary
> power with the prop control" is not good advice.
Yes, it is, depending on the engine. For the M14 and Huosai, it should work just
fine without causing any damage to the engine. For instance, with the Huosai
engine I have found no documented minimum RPM figures for a given MAP. The
only limit I can see is that you may operate at full throttle and 2250 RPM for
up to 1 hour with a 5 minute break after that. If you reduce the MAP to 28
in-Hg you may run up to 2250 RPM for a long as you want. Since BMEP decreases
with decreasing MAP, and since MAP decreases as RPM decreases, I can see nothing
that contraindicates full throttle operation with reduced RPM.
In larger radial engines there are maximum MAP values for differing RPM. The pilot
must ensure that the MAP does not exceed specifications for a given RPM and
fuel type, but even with that there is latitude to make RPM reductions without
making MAP reductions. (Maximum MAP for big radials is also different depending
on whether you are running 100/130 octane or 115/140 octane. They may also
have torque limitations as well.)
I was making the point that people who worry about pulling the prop back without
reducing the throttle first are probably avoiding a perfectly valid and safe
mode of operation.
> The fact that Bud Granley was able to reduce power in the Sea Fury in
> this manner in no way recommends this procedure for the engines we
> are operating.
The point I was making is that a radical RPM reduction will also bring a radical
reduction in MAP. As long as one does not exceed the maximum MAP for a given
RPM setting, one can continue to reduce RPM without reducing MAP.
> It is entirely possible that the R4360 in this case is
> equipped with automatic devices sensing MAP and RPM and controlling a
> waste gate.
The standard R4360 does not have an exhaust-gas-driven turbosupercharger (since
we are getting picky about names). There may have been some installations with
one fitted but I am not aware of any modified Sea Furys with such. Therefore,
there is no waste gate, a waste gate being a device that controls exhaust
gas bypass around the turbine in an exhaust-gas-driven turbosupercharger. I think
you may be thinking of what is commonly called a overpressure limit valve
that opens to reduce excessive induction system pressure.
No, in this case reducing engine RPM with the prop control reduces the RPM of the
centrifugal compressor stage ("blower") since the compressor is directly geared
to the crankshaft. The gear ratio is 6:1 in the R4360 so the "blower" rotates
at six times the crank RPM. Reducing crank RPM reduces "blower" RPM and
reduces available boost substantially.
> You may get away with that practice for a little while with the
> Huosai, M14P etc. but you will eventually fail the engine. With a
> truly supercharged engine you could destroy it in a matter of
> minutes.
Again, I believe you might not be correct in all cases. In all engines you must
adhere to the operating limitations but within that range you are free to use
various combinations of MAP and RPM. The point I made and still make is that,
with the Huosai and Vendeneyev engines, you have tremendous latitude to make
RPM reductions without making a corresponding MAP reduction. Larger radial
engines may not have the same latitude due to the greater available boost, increased
compression, or whatever. But even there it was normal to operate at very
low RPMs with relatively high MAP.
> Just as a matter of interest (and maybe generate a little
> controversy) the blower is the reason the T6/Harvard runs away from
> the CJ6 (Huosai or M14) above 6000 ft or so.
The supercharger in the R1340 is capable of overboosting the engine (exceeding
maximum allowable MAP) thus leading to a critical altitude above which the engine
cannot maintain rated power. The Huosai and Vendeneyev engines are already
running with maximum boost at sea level so they are losing power already as
they climb. Therefore I suspect you very well may be right.
--
Brian Lloyd 6501 Red Hook Plaza, Suite 201
brian@lloyd.com St. Thomas, VI 00802
+1.340.998.9447 - voice +1.360.838.9669 - fax
GMT-4
Message 27
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--> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
Walt,
I will post the pages from the 1943 book on the subject to make it clear for
everyone. What you say about the exhaust driven units is right. Was that not
why so many Merlin engines blew up on Spitfires in the early days ?
Gus
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Walt Lannon
Subject: Re: Yak-List: range
--> Yak-List message posted by: "Walt Lannon" <lannon@look.ca>
More on superchargers, I see a few misconceptions in the previous
posts; ---------
A supercharger is a device designed to increase engine manifold pressure and
therefore increase output horsepower.
The term generally refers to an internal engine driven centrifugal blower. A
turbocharger is an externally driven supercharger, driven by exhaust gases.
It could be driven by some other power source and have another name but it
would
still be a supercharger.
All supercharged engines regardless of boost source are technically
"altitude" engines and have a critical altitude. In the case of the Huosai,
M14P, AI14R, etc. the critical altitude happens to be sea level so it
becomes a moot point unless you were operating from below that level. A
normally aspirated engine has no critical altitude; ie: full throttle can be
applied at any altitude assuming RPM and fuel mixture are correct.
The critical altitude may be defined as the altitude at which full throttle
operation will not exceed the engines design rated (ie: maximum continuous)
power.
All other supercharged engines that I am aware of have a critical altitude
at some point above sea level. This is true also of a waste gated system,
the pilot may be able to apply full throttle for take-off and climb with the
waste gate automatically controlling the MAP. Upon reaching the critical
altitude the waste gate will be closed.
For example the P&W R1340 rated at 550 HP max. cont. at 32.5 in. and 2200
RPM can maintain that power to 5500 ft. in standard air with the 10:1
blower. The critical altitude of the12:1 blower model is approx. 7000 ft.
Above these points the MAP will decrease like a normally aspirated engine.
This is a simple single stage, single speed blower. There are much more
complex designs, some with turbochargers as well that can increase the
crit.alt. dramatically.
The suggestion that "one should run with the throttle wide and vary power
with the prop control" is not good advice. The fact that Bud Granley was
able to reduce power in the Sea Fury in this manner in no way recommends
this procedure for the engines we are operating. It is entirely possible
that the R4360 in this case is equipped with automatic devices sensing MAP
and RPM and controlling a waste gate.
You may get away with that practice for a little while with the Huosai, M14P
etc. but you will eventually fail the engine. With a truly supercharged
engine you could destroy it in a matter of minutes.
Just as a matter of interest (and maybe generate a little controversy) the
blower is the reason the T6/Harvard runs away from the CJ6 (Huosai or M14)
above 6000 ft or so.
Cheers;
Walt
----- Original Message -----
From: "Brian Lloyd" <brian@lloyd.com>
Subject: Re: Yak-List: range
> --> Yak-List message posted by: Brian Lloyd <brian@lloyd.com>
>
> Gus Fraser wrote:
>
> > --> Yak-List message posted by: "Gus Fraser" <fraseg@comcast.net>
> >
> > I think that it is because of the increased air pressure. Due to this
> > to maintain the mixture there is more fuel needed to maintain the
> > fuel air ratio. But hey, at any given manifold pressure and a given
> > RPM surely they produce the same power and therefore the same fuel
> > usage ? The PF engine is only a 400 HP engine when it produces 400
> > HP.
>
> But Mark is correct in that the supercharger is geared to a higher RPM for
a given crankshaft RPM therefore it requires more power to drive. When the
output shaft is delivering the same HP to the prop the 400 hp engine is
still using more fuel because there is greater hp consumed in the
supercharger.
>
> > Remember that any supercharged single stage, non boosted, non geared
> > supercharger
>
> Huh? If it has a supercharger, it is boosted.
>
> > Superchargers have a critical altitude. This is where the power of
> > the super charger has the most benefit.
>
> First, let's get our terms straight so we make sure we are speaking of
apples and apples. When I see the term "supercharger" I think of a device
that takes power from the crankshaft to power a compressor that will
increase manifold pressure. When I see the term "turbocharger" I think of a
device that uses waste power in the exhaust to turn a turbine which in turn
drives a compressor to increase manifold pressure.
>
> Turbochargers that are powered by exhaust gas do indeed have a critical
altitude above which the engine cannot sustain maximum usable manifold
pressure. In an engine with an automatic or adjustable waste gate, it is
the altitude at which the waste gate is all the way closed and the
turbocharger is providing maximum boost. If you continue to climb above
this altitude, MAP will decrease just as it does with a normally aspirated
engine.
>
> A mechanical supercharger, one that is gear-driven from the crankshaft,
always provides a fixed amount of boost, the amount of which is totally
dependent on engine RPM. For instance, the supercharger in the stock CJ6A
engine provides 85 mm-Hg of boost at 2350 RPM but only 80 mm-Hg of boost at
2250 RPM. Since all of this boost is usable, there is no critical altitude.
>
> In bigger engines with superchargers the boost available down low may be
greater than needed to achieve maximum usable MAP. (This also varies with
grade of fuel.) I presume this is what you mean by operating below critical
altitude, that being the altitude at which you can achieve maximum usable
MAP at full throttle. I guess we can consider this a critical altitude but
I believe this is a misnomer as we are not dealing with a turbocharger.
Regardless, your point is well taken. The engine is less efficient below
the altitude where you can run full throttle.
>
> OTOH, most of us learned on flat engines, either normally aspirated or
turbocharged, not round engines. (There are some airplanes that use
supercharged engines, the Twin Bonanza and the Aero Commander 680 come to
mind here, but I leave them out of this discussion.) Their use of MAP and
RPM is very different. Those engines tend to keep MAP constant as the RPM
is decreased. (MAP increases slightly as RPM is decreased in a normally
aspirated engine and stays constant in a turbocharged engine below critical
altitude.)
>
> But a round engine with a supercharger gives you TWO controls to vary MAP:
throttle *and* RPM. Hal recently posted a message about landing a Sea Fury
with the throttle stuck full open. Did anyone notice that just by pulling
the prop (RPM) way back the pilot reduced his MAP to 30"Hg? If one is
interested in efficient operation, one should plan to run with the throttle
wide and vary power using the prop control. The instrumentation in the Yak
already implies this by calibrating the tachometer (RPM) in percent-of-power
instead of RPM. The implication is that it is OK to run at 50% or 60% of
maximum RPM.
>
> > Below this altitude it uses more fuel for the reason stated above,
> > above this altitude the supercharger is not as effective because it
> > can't thicken the air enough.
>
> Well, it is still fully effective but it can only provide so much boost
and if you start with lower ambient/inlet pressure, you get lower
final/outlet pressure.
>
> > On looking in the Yak manual I found that there is specifically no
> > critical altitude. Not sure why this is
>
> There are two reasons for this:
>
> 1. it is a mechanical supercharger, not a turbocharger and;
>
> 2. full boost is allowable at sea-level.
>
> You can leave the prop and throttle full-forward as you climb out and the
MAP will decrease with altitude just like a normally aspirated engine.
>
> > but in my experiments with fuel flow and altitude I have found that
> > between 11,500 and 12,500 are best. Of course this is not to be done
> > without O2 for the weakest link in the chain, the pilot.
>
> I have also found the most efficient altitude for the CJ6A to be around
11,000'. As for O2, that is a function of the individual. The only way to
know for sure whether you need O2 at 12,500 is to use a pulse-oximeter to
measure the O2 content in your blood. When I was younger and lived at
7,000' in Colorado I found that I was fine for long periods at 14,500. I
suffered none of the effects of hypoxia at that altitude. Now I am not
comfortable for any length of time at 12,500 without O2.
>
> > I think, rather than re-gearing the M14P it would be worth looking
> > into a second stage supercharger with a pressure limiting switch.
> > What this would do is switch in the second stage above a certain
> > pressure altitude. Therefore better altitude and better X-country
> > performance without the penalty of flying at lower altitudes.
>
> Since the supercharger is geared to the engine anyway that is pretty hard
to do without total redesign of the engine. OTOH, it would be possible to
effectively create a second stage by adding a turbocharger. I believe that
was done in the B-17 and P-38 so there is prior art to adding turbochargers
to supercharged round engines.
>
> > I have a fantastic book which I got from a yard sale two years ago
> > which was written in 1943 by GM about this subject. Great book and
> > written in stupid person English, hence my understanding of the
> > subject. Great bit of history. It draws conclusions about Japanese
> > engine design and the reasons for the Zero being the way it is
> > against US doctrine on engine design. It stated that all engine
> > design is a compromise to give the best performance at a given
> > altitude.
>
> You are certainly correct on that. Every engine is a compromise for
operating conditions. Still, if we know how the engine works, it is a
fairly straight-forward path to determining what is likely to be most
efficient.
>
> --
>
> Brian Lloyd 6501 Red Hook Plaza, Suite 201
> brian@lloyd.com St. Thomas, VI 00802
> +1.340.998.9447 - voice +1.360.838.9669 - fax
> GMT-4
>
>
Message 28
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"yak-list@matronics. com" <yak-list@matronics.com>
--> Yak-List message posted by: "Jeff Linebaugh" <jefflinebaugh@earthlink.net>
Hey...for those of you who know our new YPA/RPA money man- Jim Esposito:
Jim solo'd last Thursday! Won't be long till he's yanking and banking with
us! He plans to be done with his private by Red Star!
Congrats Jim!
Jeff Linebaugh
Message 29
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| Subject: | Request from the Smoking Section..... |
--> Yak-List message posted by: "Jeff Linebaugh" <jefflinebaugh@earthlink.net>
After a surprise present from my wife, I am now among the "smoking" crowd
with our CJ. (She pulled it off in a neat way too...while we were away, she
had our mechanic install, and test the system....when we came home, we were
welcomed by a smoking flyover!)
So, a couple of questions for you "smokers".... I have heard a few options
for what to use for smoke oil....I am looking for opinions and sources for
smoke oil. I'd appreciate your help!
Thanks,
Jeff Linebaugh
jefflinebaugh@earthlink.net
Memphis, TN
Message 30
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--> Yak-List message posted by: "Rick Basiliere" <discrab@earthlink.net>
There are times here (Colorado) in the summer the Density Altitude is close
to 10K on the ground as far as O2 at night - I wonder what the cop would say
when we get stopped going to the airport using O2 because the ground is
above 5K. Oh to have the worries of a flatlander...:-) Rick
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com]On Behalf Of Roy O. Wright
Subject: Re: Yak-List: Spam Can?
--> Yak-List message posted by: "Roy O. Wright" <roy@wright.org>
Barry,
It's OK as along as you wear full helmet (properly taped) and O2 mask.
No sissy cannulas. <G>
Seriously, if you fly above 10,000 ft. daytime, or 5,000 ft. nighttime,
then O2 is recommended.
So go far it and be the envy of the hypoxiated.
Have fun,
Roy
',,'',,'',,',,'
Roy Wright 512.378.1234 mailto:royw@cisco.com
Cisco Systems import com.cisco.std-disclaimer
"Experience is the thing you get the moment after you needed to have it."
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