Tired of bumping along to Oshkosh?

[Rich S.]

http://tinyurl.com/9t6e8

Rich S.

[Darrel Toepfer]

Rich S. wrote:

> http://tinyurl.com/9t6e8

Cramped 2 seater... Burns JetA or Avgas from the one that landed here
last year during one of the hurricane evacs. Mileage is better on JetA
though, according to the pilot...

[[email protected]]

Unless something has changed, jets cant burn avgas-too hot,will burn up
turbine wheels etc.Pilot was probably bs-ing you

"Darrel Toepfer" > wrote in message
...
> Rich S. wrote:
>
>> http://tinyurl.com/9t6e8
>
> Cramped 2 seater... Burns JetA or Avgas from the one that landed here last
> year during one of the hurricane evacs. Mileage is better on JetA though,
> according to the pilot...

[john smith]

wrote:
> Unless something has changed, jets cant burn avgas-too hot,will burn up
> turbine wheels etc.Pilot was probably bs-ing you

Cessna Citation II POH states that xxxx gallons of 100LL can be burned.
I cannot remember the the stated value, it was over 20 years ago when I
read it.

[Dan, U.S. Air Force, retired]

wrote:
> Unless something has changed, jets cant burn avgas-too hot,will burn up
> turbine wheels etc.Pilot was probably bs-ing you
>
> "Darrel Toepfer" > wrote in message
> ...
>
>>Rich S. wrote:
>>
>>
>>>http://tinyurl.com/9t6e8
>>
>>Cramped 2 seater... Burns JetA or Avgas from the one that landed here last
>>year during one of the hurricane evacs. Mileage is better on JetA though,
>>according to the pilot...
>
>
>
B-36 and C-123 did it all the time.

Dan, U.S. Air Force, retired

" > wrote in message
...
> Unless something has changed, jets cant burn avgas-too hot,will burn up
> turbine wheels etc.

You certainly CAN burn AvGas in place of JP-4, JP-5, JP-8, Jet-A, Kerosene,
etc.
Details:
http://afpet.ft-belvoir.af.mil/technical_orders/pdf/42B1-1-14_REV.pdf

>Pilot was probably bs-ing you.
Likely the pilot knew more than you.


Barren

[CB]

B36's at least had a lot of lead buildup on the tailpipes.

[Big John]

Barren

Concur.

In early days in P-80 when every base didn't have JP-1 it was
authorized to fill up with av gas to get home. Did on numerous
occasions and no damage to J-33.

Big John
`````````````````````````````````````````````````` `````````````````````````````````````````````````` `

On Fri, 5 Aug 2005 10:01:35 -0700, > wrote:

>
" > wrote in message
...
>> Unless something has changed, jets cant burn avgas-too hot,will burn up
>> turbine wheels etc.
>
>You certainly CAN burn AvGas in place of JP-4, JP-5, JP-8, Jet-A, Kerosene,
>etc.
>Details:
>http://afpet.ft-belvoir.af.mil/technical_orders/pdf/42B1-1-14_REV.pdf
>
>>Pilot was probably bs-ing you.
>Likely the pilot knew more than you.
>
>
>Barren
>

[Montblack]

("Big John" wrote)
> In early days in P-80 when every base didn't have JP-1 it was
> authorized to fill up with av gas to get home. Did on numerous
> occasions and no damage to J-33.


Do you recall the fuel burn with Avgas? Was it similar - 100 gph vs 100 gph,
or whatever a P-80 burned? Performance differences? Curious.

Thanks.


Montblack

[Rich S.]

"Montblack" > wrote in message
...
> ("Big John" wrote)
>> In early days in P-80 when every base didn't have JP-1 it was
>> authorized to fill up with av gas to get home. Did on numerous
>> occasions and no damage to J-33.
>
>
> Do you recall the fuel burn with Avgas? Was it similar - 100 gph vs 100
> gph, or whatever a P-80 burned? Performance differences? Curious.

I'll bet his tailpipe looked like the exhaust stacks on the jet truck at
Oshkosh. VAROOOOOMMMM!!!!

Rich "Let's light 'em up!" S.

[[email protected]]

I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.


"Rich S." > wrote in message
...
> http://tinyurl.com/9t6e8
>
> Rich S.
>

[Dan, U.S. Air Force, retired]

wrote:
> I stand by my original post, in a jet engine you compress the fuel
> approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
> except in a emergency can burn up the combustion chambers and burn the
> turbine wheels severely. You can not feed them on a regular basis.
>
>
So the aircraft I cited that DID use avgas in jet engines on every
flight don't count?

Dan, U.S. Air Force, retired

[Matt Whiting]

wrote:
> I stand by my original post, in a jet engine you compress the fuel
> approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
> except in a emergency can burn up the combustion chambers and burn the
> turbine wheels severely. You can not feed them on a regular basis.

Funny, most engines I'm aware of compress the air, or the air/fuel
mixture, but don't try to compress the fuel.


Matt

[Cy Galley]

Where are you getting these "compression" figures?

" > wrote in message
...
>I stand by my original post, in a jet engine you compress the fuel
>approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
>except in a emergency can burn up the combustion chambers and burn the
>turbine wheels severely. You can not feed them on a regular basis.
>
>
> "Rich S." > wrote in message
> ...
>> http://tinyurl.com/9t6e8
>>
>> Rich S.
>>
>
>

[Rich S.]

" > wrote in message
...
>I stand by my original post, in a jet engine you compress the fuel
>approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
>except in a emergency can burn up the combustion chambers and burn the
>turbine wheels severely. You can not feed them on a regular basis.
>
>
> "Rich S." > wrote in message
> ...
>> http://tinyurl.com/9t6e8
>>
>> Rich S.
>>
>
>

Why are you referencing my post?

Rich S.

[RST Engineering]

Most piston engines I'm familiar with compress the fuel/air mixture 8-10:1,
not 14:1. Since the fuel is delivered to a jet engine AFTER the compressor
stages (which compress the ambient air only) I'm having trouble wrapping my
head around the 70:1 compression ratio.

Jim



" > wrote in message
...
>I stand by my original post, in a jet engine you compress the fuel
>approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
>except in a emergency can burn up the combustion chambers and burn the
>turbine wheels severely. You can not feed them on a regular basis.

[Darrel Toepfer]

wrote:

> Unless something has changed, jets cant burn avgas-too hot,will burn up
> turbine wheels etc.Pilot was probably bs-ing you

Nothing has changed, the reverse cycle just doesn't work. ie. you
typically can't burn JetA in an AvGas engine...

I had a key to the mogas pump, I believe he said it would burn that as
well. He opted to wait for the FBO to pump the JetA, had to page him and
wait 45 minutes or so...

[jls]

I had fun bumping along to Oshkosh. When the bumps got too bad me and the
old gal changed altitude or didn't fly above the roads or over the big
metal-roofed barns which made such considerable thermals. 500' agl sure
was fun, though, chasing and racing 18-wheelers and an occasional hawk,
buzzard, or crow.

Last time bumping along it was nice to have that 10 closest airports feature
on the GPS for getting on the ground when the thunderstorms closed in.

Last time in Oshkosh it was those kids on green JD 4ormore-wheelers you had
to look out for. They would run you down.

[UltraJohn]

RST Engineering wrote:

> Most piston engines I'm familiar with compress the fuel/air mixture
> 8-10:1,
> not 14:1. Since the fuel is delivered to a jet engine AFTER the
> compressor stages (which compress the ambient air only) I'm having trouble
> wrapping my head around the 70:1 compression ratio.
>
> Jim
>
>
Jim
From what I recall (disclaimer my recall isn't the best!) his compress ratio
is probably ok but you are correct the only part that is being compressed
is the air, the fuel burn "powers" the turbine which is connected to the
compressor to produce more power. The excess heat is discharged out the
exhaust. In a Fan jet the compressor is made bigger to flow more air than
the "turbojet" can ignite and the excess is routed around the turbine so
you have more airflow with less waste heat out the exhaust.
Am I close?

John

[[email protected]]

Has anyone here been certified to actually work on a jet engine, how would
you keep from exceeding 620 degrees egt, the fuel control cant operate under
the avgas parameters in correcting the egt, the retired af person does not
appear to know anything about a jet engine. In a J-57 where you have 16
stages of compression prior to injecting the fuel in the combustion chamber
how would you bleed off enough air and still maintain power using avgas, the
combustion chambers and rest of the hot section can not take the extreme
heat of regular avgas, the flashpoint is too high compared to jp-4 or
similar fuel. How could the fuel control work properly when it is lubricated
by the jp-4. please tell me

"Bryan Martin" > wrote in message
...
> As I recall, the biggest problem with burning gasoline in a turbine is the
> the TBO is shortened due to the lower lubricating qualities of gasoline
> over
> jet fuel. The fuel pumps and injectors wear out quicker.
>
>
> in article , at
> wrote on 8/5/05 11:14 PM:
>
>> I stand by my original post, in a jet engine you compress the fuel
>> approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
>> except in a emergency can burn up the combustion chambers and burn the
>> turbine wheels severely. You can not feed them on a regular basis.
>>
>>
>> "Rich S." > wrote in message
>> ...
>>> http://tinyurl.com/9t6e8
>>>
>>> Rich S.
>>>
>>
>>
>

[Dan, U.S. Air Force, retired]

wrote:
> Has anyone here been certified to actually work on a jet engine, how would
> you keep from exceeding 620 degrees egt, the fuel control cant operate under
> the avgas parameters in correcting the egt, the retired af person does not
> appear to know anything about a jet engine. In a J-57 where you have 16
> stages of compression prior to injecting the fuel in the combustion chamber
> how would you bleed off enough air and still maintain power using avgas, the
> combustion chambers and rest of the hot section can not take the extreme
> heat of regular avgas, the flashpoint is too high compared to jp-4 or
> similar fuel. How could the fuel control work properly when it is lubricated
> by the jp-4. please tell me

Not all jet engines used jet fuel for lubrication, not all jet
engines are axial flow and if I recall correctly the USAF stopped using
JP-4 years ago. Ever heard of JP-5 or JP-8? The fact remains the B-36
and C-123 used avgas in their jet engines. I never worked on either but
I worked with men who did. The B-36 used four J47-GE-19 jet engines on
take off, high altitude and for dash speed. The C-123 used J-44R3 and
J-69 engines. In neither aircraft were there separate tanks for jet fuel.

As for jet engines while I was not a jet mech I worked the engine
instrumentations systems on C-130A, HC-130, AC-130, KC-135, C-141, T-33,
T-39, F-4E, UH-1P, HH-3, MH-53, UH-60, MH-60, several recips and a few
aircraft I will not mention.

As for your J-57 example I assume you have been looking at cut away
pictures. OK, let's do that. Take a look at the size of the inlet. It is
much bigger than needed to compress the air for combustion. Guess what,
that's done on purpose. It's done to take in a volume of air to cool the
engine.

Now tell me all about your experience with jet engines. Tell me all
about your vast experience that leads you to question my experience.


Dan, U.S. Air Force, retired

[Andy Asberry]

On Sat, 06 Aug 2005 13:57:33 -0400, Bryan Martin
> wrote:

>See: http://encyclopedia.laborlawtalk.com/Jet_engine
>
>According to this article, modern turbine engines may achieve compression
>ratios of as high as 44:1 at very high altitudes (very cold intake air). But
>the compression ratio of a turbine engine can't be compared directly with
>the compression ratio of piston engines due to the differences between
>cyclic combustion and continuous combustion, among other things. He may have
>been referring to fuel/air ratios with the 14:1 and 70:1 numbers, but they
>still don't sound quite right.
>
>In any case, just because gasoline is burned at a certain F/A ratio and
>compression ratio in a piston engine has nothing to do with how you would
>burn it in a turbine. Piston engines operate at near stoiciometric mixtures:
>nearly all the oxygen and all the fuel react with each other leaving very
>little of either in the exhaust. This can not be done in a turbine. No
>matter what fuel is used it would result in melt-down of the hot section of
>the engine. Most of the air passing through a turbine engine is used to keep
>it cool. Only a small portion of the available oxygen is used to burn the
>fuel. Theoretically, just about any fluid fuel could be used in a turbine as
>long as you can produce a combustible mixture in the core of the combustor
>and pump enough excess air through it keep it cool. You could probably burn
>powdered solid fuels in a turbine if you could manage to feed a steady
>stream of it to in the combustors and get it to mix properly.
>
>Hmmm, a coal burning jet engine?

Or flour?

[Jim Carriere]

Bryan Martin wrote:
> As I recall, the biggest problem with burning gasoline in a turbine is the
> the TBO is shortened due to the lower lubricating qualities of gasoline over
> jet fuel. The fuel pumps and injectors wear out quicker.

Another related durability problem is lead deposits on the turbine
blades. I'm not sure this was a significant problem with very early
jet engines run on avgas, since they didn't last thousands of hours
like nowadays.

Possible problems while running the engine could result from the
different fluid properties of the fuel. For example, gasoline is
thinner and evaporates at a lower temperature, so acceleration and
deceleration might be affected, vapor lock might occur.

Steady state the engine will run the same. Heat and pressure is what
drives the turbine, and it doesn't matter if the heat comes from Jet
A, 100LL, turpentine, or whatever.

[[email protected]]

To AF retired, my experience? I was a jet engine mechanic AF43250, so I know
what I am talking about. As far as the cold section of the engine it has
what is called a convergent-divergent duct system to compress the air to 70
parts oxygen to one part fuel, however the engine can't use all the air up
to approximately 80% power so it exhausts it thru the bleed valve on the
side of the engine.Again, check any engine guide and gasoline engines have
approximately 14 parts oxygen to 1 part fuel, doesn't matter how its
compressed. The fuel control controls the amount of fuel injected into the
engine but it relies on pressure sensors and temperature sensors to do that.
Using avgas the egt would go very high because of its quick burning
characteristics compared to kerosene or other jets fuels therefore the
pressure and temperature sensors would send that information to the fuel
control for adjustment. The fuel control also is lubricated by jet fuel and
would soon fail without this lubrication ( it is so critical that we had to
submerge the fuel control in jet fuel for 24 hours prior to installation and
then if we manually moved the controls more the three times prior to
installation we had to send it back for rebuilding. Incidentally, I also
worked on F-102.T-33,B-57,T-39,C-130,C-133,F-101,all the aircraft had the
same requirements for fuel. Perhaps the more modern engine have more
tolerant materials , however when talking to recent jet engine mechanics
they say the requirements are the same. As I understand it the aircraft you
flew on used the jets for takeoff and at times at altitude only, if that's
truly the case the engine may be able to operate on avgas at those times and
those times only.

"Jim Carriere" > wrote in message
...
> Bryan Martin wrote:
>> As I recall, the biggest problem with burning gasoline in a turbine is
>> the
>> the TBO is shortened due to the lower lubricating qualities of gasoline
>> over
>> jet fuel. The fuel pumps and injectors wear out quicker.
>
> Another related durability problem is lead deposits on the turbine blades.
> I'm not sure this was a significant problem with very early jet engines
> run on avgas, since they didn't last thousands of hours like nowadays.
>
> Possible problems while running the engine could result from the different
> fluid properties of the fuel. For example, gasoline is thinner and
> evaporates at a lower temperature, so acceleration and deceleration might
> be affected, vapor lock might occur.
>
> Steady state the engine will run the same. Heat and pressure is what
> drives the turbine, and it doesn't matter if the heat comes from Jet A,
> 100LL, turpentine, or whatever.

[Dan, U.S. Air Force, retired]

wrote:
> To AF retired, my experience? I was a jet engine mechanic AF43250, so I know
> what I am talking about. As far as the cold section of the engine it has
> what is called a convergent-divergent duct system to compress the air to 70
> parts oxygen to one part fuel, however the engine can't use all the air up
> to approximately 80% power so it exhausts it thru the bleed valve on the
> side of the engine.

J-33s had bleed air? Please explain to me the J-33 used "convergent -
divergent" air flow.


Again, check any engine guide and gasoline engines have
> approximately 14 parts oxygen to 1 part fuel, doesn't matter how its
> compressed. The fuel control controls the amount of fuel injected into the
> engine but it relies on pressure sensors and temperature sensors to do that.
> Using avgas the egt would go very high because of its quick burning
> characteristics compared to kerosene or other jets fuels therefore the
> pressure and temperature sensors would send that information to the fuel
> control for adjustment. The fuel control also is lubricated by jet fuel and
> would soon fail without this lubrication ( it is so critical that we had to
> submerge the fuel control in jet fuel for 24 hours prior to installation and
> then if we manually moved the controls more the three times prior to
> installation we had to send it back for rebuilding.

The lead in AvGas would have acted as a lubricant long enough to get
where you were going.

Incidentally, I also
> worked on F-102.T-33,B-57,T-39,C-130,C-133,F-101,all the aircraft had the
> same requirements for fuel.

When you get a chance look at the -1 TOs for those aircraft. They
list substitute fuels. A lot has changed since you were in, I'm assuming
1960ish, but fuel characteristics.

You worked on all those aircraft in less than 6 years in the USAF? It
took me 20 to do the aircraft I listed.



Perhaps the more modern engine have more
> tolerant materials , however when talking to recent jet engine mechanics
> they say the requirements are the same. As I understand it the aircraft you
> flew on used the jets for takeoff and at times at altitude only, if that's
> truly the case the engine may be able to operate on avgas at those times and
> those times only.

Do us both a favour and do some research on the subject, OK? Try
Google. Telling me I don't know what I am talking about doesn't quite
make for civil discourse. BTW, I never said I flew on B-36s or C-123s.

Dan, U.S. Air Force, retired

[[email protected]]

The J-33 is not a axial flow engine, it is centrifical flow with one stage
of compression, AF I suggest YOU are the one who needs to read up on the
subject and not me, btw do you believe everything that google returns as the
factual information, I suggest you keep in your line of expertise and don't
go outside of either apg or flt engineer, you definitely aren't experienced
enough to debate jet engines and their feeding.

"Dan, U.S. Air Force, retired" > wrote in message
news:QvnJe.71991$FP2.65700@lakeread03...
> wrote:
>> To AF retired, my experience? I was a jet engine mechanic AF43250, so I
>> know what I am talking about. As far as the cold section of the engine it
>> has what is called a convergent-divergent duct system to compress the air
>> to 70 parts oxygen to one part fuel, however the engine can't use all the
>> air up to approximately 80% power so it exhausts it thru the bleed valve
>> on the side of the engine.
>
> J-33s had bleed air? Please explain to me the J-33 used "convergent -
> divergent" air flow.
>
>
> Again, check any engine guide and gasoline engines have
>> approximately 14 parts oxygen to 1 part fuel, doesn't matter how its
>> compressed. The fuel control controls the amount of fuel injected into
>> the engine but it relies on pressure sensors and temperature sensors to
>> do that. Using avgas the egt would go very high because of its quick
>> burning characteristics compared to kerosene or other jets fuels
>> therefore the pressure and temperature sensors would send that
>> information to the fuel control for adjustment. The fuel control also is
>> lubricated by jet fuel and would soon fail without this lubrication ( it
>> is so critical that we had to submerge the fuel control in jet fuel for
>> 24 hours prior to installation and then if we manually moved the controls
>> more the three times prior to installation we had to send it back for
>> rebuilding.
>
> The lead in AvGas would have acted as a lubricant long enough to get
> where you were going.
>
> Incidentally, I also
>> worked on F-102.T-33,B-57,T-39,C-130,C-133,F-101,all the aircraft had the
>> same requirements for fuel.
>
> When you get a chance look at the -1 TOs for those aircraft. They list
> substitute fuels. A lot has changed since you were in, I'm assuming
> 1960ish, but fuel characteristics.
>
> You worked on all those aircraft in less than 6 years in the USAF? It
> took me 20 to do the aircraft I listed.
>
>
>
> Perhaps the more modern engine have more
>> tolerant materials , however when talking to recent jet engine mechanics
>> they say the requirements are the same. As I understand it the aircraft
>> you flew on used the jets for takeoff and at times at altitude only, if
>> that's truly the case the engine may be able to operate on avgas at those
>> times and those times only.
>
> Do us both a favour and do some research on the subject, OK? Try
> Google. Telling me I don't know what I am talking about doesn't quite make
> for civil discourse. BTW, I never said I flew on B-36s or C-123s.
>
> Dan, U.S. Air Force, retired

[Dan, U.S. Air Force, retired]

wrote:

> The J-33 is not a axial flow engine, it is centrifical flow with one stage
> of compression, AF I suggest YOU are the one who needs to read up on the
> subject and not me, btw do you believe everything that google returns as the
> factual information, I suggest you keep in your line of expertise and don't
> go outside of either apg or flt engineer, you definitely aren't experienced
> enough to debate jet engines and their feeding.

You never made the distinction between types of engines. You said
"As far as the cold section of the engine it as what is called a
convergent- divergent duct system to compress the air to 70 parts oxygen
to one part fuel, however the engine can't use all the air up to
approximately 80% power so it exhausts it thru the bleed valve on the
side of the engine."

Try saying what you actually mean.

I told you what my job was and it certainly wasn't a flight engineer.

If you really were in the Air Force it wasn't very long since you
never went beyond 5 level. How does that compare with my 20 years?

As for Google I never said I believed everything or anything, I
simply suggested you try using it instead of insulting me.

Since you refuse to be civil this discussion is closed.

Dan, U.S. Air Force, retired and damned proud of it


>
> "Dan, U.S. Air Force, retired" > wrote in message
> news:QvnJe.71991$FP2.65700@lakeread03...
>
wrote:
>>
>>>To AF retired, my experience? I was a jet engine mechanic AF43250, so I
>>>know what I am talking about. As far as the cold section of the engine it
>>>has what is called a convergent-divergent duct system to compress the air
>>>to 70 parts oxygen to one part fuel, however the engine can't use all the
>>>air up to approximately 80% power so it exhausts it thru the bleed valve
>>>on the side of the engine.
>>
>> J-33s had bleed air? Please explain to me the J-33 used "convergent -
>>divergent" air flow.
>>
>>
>>Again, check any engine guide and gasoline engines have
>>
>>>approximately 14 parts oxygen to 1 part fuel, doesn't matter how its
>>>compressed. The fuel control controls the amount of fuel injected into
>>>the engine but it relies on pressure sensors and temperature sensors to
>>>do that. Using avgas the egt would go very high because of its quick
>>>burning characteristics compared to kerosene or other jets fuels
>>>therefore the pressure and temperature sensors would send that
>>>information to the fuel control for adjustment. The fuel control also is
>>>lubricated by jet fuel and would soon fail without this lubrication ( it
>>>is so critical that we had to submerge the fuel control in jet fuel for
>>>24 hours prior to installation and then if we manually moved the controls
>>>more the three times prior to installation we had to send it back for
>>>rebuilding.
>>
>> The lead in AvGas would have acted as a lubricant long enough to get
>>where you were going.
>>
>>Incidentally, I also
>>
>>>worked on F-102.T-33,B-57,T-39,C-130,C-133,F-101,all the aircraft had the
>>>same requirements for fuel.
>>
>> When you get a chance look at the -1 TOs for those aircraft. They list
>>substitute fuels. A lot has changed since you were in, I'm assuming
>>1960ish, but fuel characteristics.
>>
>> You worked on all those aircraft in less than 6 years in the USAF? It
>>took me 20 to do the aircraft I listed.
>>
>>
>>
>>Perhaps the more modern engine have more
>>
>>>tolerant materials , however when talking to recent jet engine mechanics
>>>they say the requirements are the same. As I understand it the aircraft
>>>you flew on used the jets for takeoff and at times at altitude only, if
>>>that's truly the case the engine may be able to operate on avgas at those
>>>times and those times only.
>>
>> Do us both a favour and do some research on the subject, OK? Try
>>Google. Telling me I don't know what I am talking about doesn't quite make
>>for civil discourse. BTW, I never said I flew on B-36s or C-123s.
>>
>>Dan, U.S. Air Force, retired
>
>
>

[RST Engineering]

It would appear as though we have another "wood species expert" in our
midst.

In the first place, your original post used the term "compression ratio",
not air-fuel ratio. I doubt you know what you are talking about.

PLONK.


Jim



" > wrote in message
...
> To AF retired, my experience? I was a jet engine mechanic AF43250, so I
> know what I am talking about.

[[email protected]]

Sorry Dan, Very true that I was in the Af in the 60's, however the 5 level
in 43250 indicates expert rating, 43270 would be inspections level. I worked
on that many aircraft because in the 60's they didn't have as many jet
engine mechanics as perhaps they have today, also as I was assigned to the
flight line I had to be proficient on multiple aircraft as many different
types visited Andrews afb, and the Clark afb. I apologize if I got feisty,
it just seemed with some of the comments from everyone that some doubted my
expertise and I attempted to explain what was reality versus logical with
jet engines.


"Dan, U.S. Air Force, retired" > wrote in message
news:8joJe.73553$FP2.30579@lakeread03...
> wrote:
>
>> The J-33 is not a axial flow engine, it is centrifical flow with one
>> stage of compression, AF I suggest YOU are the one who needs to read up
>> on the subject and not me, btw do you believe everything that google
>> returns as the factual information, I suggest you keep in your line of
>> expertise and don't go outside of either apg or flt engineer, you
>> definitely aren't experienced enough to debate jet engines and their
>> feeding.
>
> You never made the distinction between types of engines. You said "As
> far as the cold section of the engine it as what is called a convergent-
> divergent duct system to compress the air to 70 parts oxygen to one part
> fuel, however the engine can't use all the air up to approximately 80%
> power so it exhausts it thru the bleed valve on the side of the engine."
>
> Try saying what you actually mean.
>
> I told you what my job was and it certainly wasn't a flight engineer.
>
> If you really were in the Air Force it wasn't very long since you never
> went beyond 5 level. How does that compare with my 20 years?
>
> As for Google I never said I believed everything or anything, I simply
> suggested you try using it instead of insulting me.
>
> Since you refuse to be civil this discussion is closed.
>
> Dan, U.S. Air Force, retired and damned proud of it
>
>
>>
>> "Dan, U.S. Air Force, retired" > wrote in message
>> news:QvnJe.71991$FP2.65700@lakeread03...
>>
wrote:
>>>
>>>>To AF retired, my experience? I was a jet engine mechanic AF43250, so I
>>>>know what I am talking about. As far as the cold section of the engine
>>>>it has what is called a convergent-divergent duct system to compress the
>>>>air to 70 parts oxygen to one part fuel, however the engine can't use
>>>>all the air up to approximately 80% power so it exhausts it thru the
>>>>bleed valve on the side of the engine.
>>>
>>> J-33s had bleed air? Please explain to me the J-33 used "convergent -
>>> divergent" air flow.
>>>
>>>
>>>Again, check any engine guide and gasoline engines have
>>>
>>>>approximately 14 parts oxygen to 1 part fuel, doesn't matter how its
>>>>compressed. The fuel control controls the amount of fuel injected into
>>>>the engine but it relies on pressure sensors and temperature sensors to
>>>>do that. Using avgas the egt would go very high because of its quick
>>>>burning characteristics compared to kerosene or other jets fuels
>>>>therefore the pressure and temperature sensors would send that
>>>>information to the fuel control for adjustment. The fuel control also is
>>>>lubricated by jet fuel and would soon fail without this lubrication ( it
>>>>is so critical that we had to submerge the fuel control in jet fuel for
>>>>24 hours prior to installation and then if we manually moved the
>>>>controls more the three times prior to installation we had to send it
>>>>back for rebuilding.
>>>
>>> The lead in AvGas would have acted as a lubricant long enough to get
>>> where you were going.
>>>
>>>Incidentally, I also
>>>
>>>>worked on F-102.T-33,B-57,T-39,C-130,C-133,F-101,all the aircraft had
>>>>the same requirements for fuel.
>>>
>>> When you get a chance look at the -1 TOs for those aircraft. They list
>>> substitute fuels. A lot has changed since you were in, I'm assuming
>>> 1960ish, but fuel characteristics.
>>>
>>> You worked on all those aircraft in less than 6 years in the USAF? It
>>> took me 20 to do the aircraft I listed.
>>>
>>>
>>>
>>>Perhaps the more modern engine have more
>>>
>>>>tolerant materials , however when talking to recent jet engine mechanics
>>>>they say the requirements are the same. As I understand it the aircraft
>>>>you flew on used the jets for takeoff and at times at altitude only, if
>>>>that's truly the case the engine may be able to operate on avgas at
>>>>those times and those times only.
>>>
>>> Do us both a favour and do some research on the subject, OK? Try
>>> Google. Telling me I don't know what I am talking about doesn't quite
>>> make for civil discourse. BTW, I never said I flew on B-36s or C-123s.
>>>
>>>Dan, U.S. Air Force, retired
>>
>>

[[email protected]]

Bryan,
a jet engine does use all the air it intakes after 80% throttle, prior to
80% the engine bleeds the part of the air not needed to the atmosphere thru
a valve mounted on the side of the engine called a bleed valve. You are
right about physics however the kerosene needs much more air then gasoline
to achieve proper combustion.

"Bryan Martin" > wrote in message
...
> Gasoline fueled reciprocating engines may use a 14:1 oxygen to fuel ratio
> but this is totally irrelevant when discussing jet engines. Reciprocating
> engines combine all the oxygen they take in with the fuel, jet engines do
> not. You may have been a really good jet mechanic but you obviously don't
> know much about the physics involved.
>
> in article , at
> wrote on 8/7/05 8:14 AM:
>
>> what is called a convergent-divergent duct system to compress the air to
>> 70
>> parts oxygen to one part fuel, however the engine can't use all the air
>> up
>> to approximately 80% power so it exhausts it thru the bleed valve on the
>> side of the engine.Again, check any engine guide and gasoline engines
>> have
>> approximately 14 parts oxygen to 1 part fuel, doesn't matter how its
>> compressed.
>

[Morgans]

"RST Engineering" > wrote in message
...
> It would appear as though we have another "wood species expert" in our
> midst.
>
> In the first place, your original post used the term "compression ratio",
> not air-fuel ratio. I doubt you know what you are talking about.
>
> PLONK.

Same person? In not, it is so close to be scary.
--
Jim in NC

[RST Engineering]

If you saw the email he sent me, it would erase all doubt.

Jim




"Morgans" > wrote in message
...
>
> "RST Engineering" > wrote in message
> ...
>> It would appear as though we have another "wood species expert" in our
>> midst.
>>
>> In the first place, your original post used the term "compression ratio",
>> not air-fuel ratio. I doubt you know what you are talking about.
>>
>> PLONK.
>
> Same person? In not, it is so close to be scary.
> --
> Jim in NC
>

[Morgans]

"RST Engineering" > wrote in message
...
> If you saw the email he sent me, it would erase all doubt.
>
> Jim

Sad.

[Dan, U.S. Air Force, retired]

Morgans wrote:
> "RST Engineering" > wrote in message
> ...
>
>>It would appear as though we have another "wood species expert" in our
>>midst.
>>
>>In the first place, your original post used the term "compression ratio",
>>not air-fuel ratio. I doubt you know what you are talking about.
>>
>>PLONK.
>
>
> Same person? In not, it is so close to be scary.

I was begining to think of tarver who was also a jet mech.


Dan, U.S. Air Force, retired

[[email protected]]

Sorry I interfered in your little group, you like to state your opinions
without really having true facts, enjoy yourselves ,you all aren't worth any
other replies

"Dan, U.S. Air Force, retired" > wrote in message
news:wozJe.73687$FP2.66037@lakeread03...
> Morgans wrote:
>> "RST Engineering" > wrote in message
>> ...
>>
>>>It would appear as though we have another "wood species expert" in our
>>>midst.
>>>
>>>In the first place, your original post used the term "compression ratio",
>>>not air-fuel ratio. I doubt you know what you are talking about.
>>>
>>>PLONK.
>>
>>
>> Same person? In not, it is so close to be scary.
>
> I was begining to think of tarver who was also a jet mech.
>
>
> Dan, U.S. Air Force, retired

[Morgans]

"Bryan Martin" > wrote

> As long as you can maintain a burnable mixture in the
> core of the combustor, you can burn anything you want in a turbine and
> you'll still see higher F/A ratios than you'll ever see in a recip.
>
> The simple fact is, gasoline can be burned in turbine engines because it
IS
> burned in turbine engines and this practice is approved by the engine
> manufacturers as long as certain adjustments are made to the TBO of the
> engine. Look up the operators manual for the Citation II and see for
> yourself.

We believe you, and Dan, cause MOST of us here have a pretty good built in
BS detector.
--
Jim in NC

[Montblack]

wrote)
> Sorry I interfered in your little group, you like to state your opinions
> without really having true facts, enjoy yourselves ,you all aren't worth
> any other replies


You have information and experience to share with some people. While that's
going on ...many, many more people are lurking - we're reading, learning,
questioning ...and enjoying ourselves <g>.

Stick around... for the lurkers :-)


Montblack

[[email protected]]

Thank you Montblack, although I was clumsy with my wording I am not a phony,
some of the others are.The information I shared was factual 50 years ago and
still factual today. Don't believe most of their replies as they are ill
informed,check with any other jet engine mechanic . Thank you for believing
in me. Contact me whenever you need anything as I have done many other
things in the following 50 years.

"Montblack" > wrote in message
...
> wrote)
>> Sorry I interfered in your little group, you like to state your opinions
>> without really having true facts, enjoy yourselves ,you all aren't worth
>> any other replies
>
>
> You have information and experience to share with some people. While
> that's going on ...many, many more people are lurking - we're reading,
> learning, questioning ...and enjoying ourselves <g>.
>
> Stick around... for the lurkers :-)
>
>
> Montblack

[Flyingmonk]

So it is a language issue, not a knowledge issue? That's
enderstandable.

[Matt Whiting]

wrote:
> Sorry I interfered in your little group, you like to state your opinions
> without really having true facts, enjoy yourselves ,you all aren't worth any
> other replies

Funny, from my vantage point watching this thread, you are about the
only one who hasn't provided a reference to support his position.

Matt

[[email protected]]

Matt, what kind of reference could I use that would be acceptable to you,
the engines that I was referring to are 40-50 years old and I was providing
my information from my personal memory, yes I know, sometimes I have a great
memory but is very short, however even the gentleman that provided the fort
belvoir link on fuels stated the same information that I was, and that it
can only be used in an emergency for a very short duration. If you would
like me to be specific as to why I can be but it isn't a short explanation.


"Matt Whiting" > wrote in message
...
> wrote:
>> Sorry I interfered in your little group, you like to state your opinions
>> without really having true facts, enjoy yourselves ,you all aren't worth
>> any other replies
>
> Funny, from my vantage point watching this thread, you are about the only
> one who hasn't provided a reference to support his position.
>
> Matt

[Matt Whiting]

wrote:
> Matt, what kind of reference could I use that would be acceptable to you,
> the engines that I was referring to are 40-50 years old and I was providing
> my information from my personal memory, yes I know, sometimes I have a great
> memory but is very short, however even the gentleman that provided the fort
> belvoir link on fuels stated the same information that I was, and that it
> can only be used in an emergency for a very short duration. If you would
> like me to be specific as to why I can be but it isn't a short explanation.
>
>
> "Matt Whiting" > wrote in message
> ...
>
wrote:
>>
>>>Sorry I interfered in your little group, you like to state your opinions
>>>without really having true facts, enjoy yourselves ,you all aren't worth
>>>any other replies
>>
>>Funny, from my vantage point watching this thread, you are about the only
>>one who hasn't provided a reference to support his position.
>>
>>Matt

A link to a manufacturer's operations manual, etc. It just seemed odd
to me that you were saying "trust me" and others were saying "trust me",
yet you claim that they don't have the facts and you do. It seemed to
me that if anything both positions were at parity. I didn't see any
data beyond "trust me" that would tip the argument one way vs. the
other. That was my only point.

I searched around the other night and found a few references, but they
weren't all that conclusive with regard to fuel usage in turbines.

Matt

[[email protected]]

In retrospect I have to concur with your point Matt, I will try to look
around and see if I have any old USAF tech manuals, but I wouldn't expect
that after this amount of time I will be successful.
P.S.
I also searched P&W site the other night but not very successful there, they
have scant information on vintage or newer engines available to the public.

"Matt Whiting" > wrote in message
...
> wrote:
>> Matt, what kind of reference could I use that would be acceptable to you,
>> the engines that I was referring to are 40-50 years old and I was
>> providing my information from my personal memory, yes I know, sometimes I
>> have a great memory but is very short, however even the gentleman that
>> provided the fort belvoir link on fuels stated the same information that
>> I was, and that it can only be used in an emergency for a very short
>> duration. If you would like me to be specific as to why I can be but it
>> isn't a short explanation.
>>
>>
>> "Matt Whiting" > wrote in message
>> ...
>>
wrote:
>>>
>>>>Sorry I interfered in your little group, you like to state your opinions
>>>>without really having true facts, enjoy yourselves ,you all aren't worth
>>>>any other replies
>>>
>>>Funny, from my vantage point watching this thread, you are about the only
>>>one who hasn't provided a reference to support his position.
>>>
>>>Matt
>
> A link to a manufacturer's operations manual, etc. It just seemed odd to
> me that you were saying "trust me" and others were saying "trust me", yet
> you claim that they don't have the facts and you do. It seemed to me that
> if anything both positions were at parity. I didn't see any data beyond
> "trust me" that would tip the argument one way vs. the other. That was my
> only point.
>
> I searched around the other night and found a few references, but they
> weren't all that conclusive with regard to fuel usage in turbines.
>
> Matt

[Morgans]

" > wrote in message
...
> In retrospect I have to concur with your point Matt, I will try to look
> around and see if I have any old USAF tech manuals, but I wouldn't expect
> that after this amount of time I will be successful.

What about the info that the B-36 jet engines used the only fuel available
on the airplane? Gas! That was not for emergency use, but every day use.

I don't want to sound like a flame. I think it is very admirable that you
backed up a bit on your hard line, and admitted that there was something you
might need to learn. Stick around. There is a great core of knowledge and
experience in this group.

See ya-
--
Jim in NC