JF-17 Thunder Multirole Fighter [Thread 7]

[messiach]

Be patient. These are friends/enthusiastic junior members who want to learn.

You guys are not even trying to understand are you?

 

[CriticalThought]

Correct.

Wrong. The following has nothing to do with 'throttle input'.

https://www.google.com/patents/US4856962

In aircraft gas turbines compressors are used to compress the air entering the gas turbine. For maximum efficiency the airflow entering the upstream end of the compressor must have a precise axial orientation with this orientation determined by the pitch of inlet guide vanes directing the air to the first rotor stages. Since variable operating conditions are encountered it is known to use variable inlet guide vanes which may be rotated around an axis varying the pitch to optimize the particular operating condition.

 

[razgriz19]

Wrong. The following has nothing to do with 'throttle input'.

https://www.google.com/patents/US4856962

Okay I'm going to be patient with you as advised by Messiach.

What do you think this statement means? I got it from the blurb you posted.

"Since variable operating conditions are encountered it is known to use variable inlet guide vanes which may be rotated around an axis varying the pitch to optimize the particular operating condition."

How do you think "variable operations conditions are encountered"?

It means the operator is asking for more or less power through "throttle input"

If the operator wants less power, he/she would decrease the fuel flow through "throttle input". Once the fuel flow is low you can't have too much air in the combustion chamber as the mixture would be too lean and you can flame out the engine. In that situation VIGV would come into action and increase their angle so that air going in to the compressor would take longer to get to the combustion chamber (in layman's term) and in mean time some valves woild open and dump the excess air from the compressor in order to ---wait for it-- "optimize the particular operating condition."

Taken from your post again.

 

[CriticalThought]

Okay I'm going to be patient with you as advised by Messiach.

What do you think this statement means? I got it from the blurb you posted.

"Since variable operating conditions are encountered it is known to use variable inlet guide vanes which may be rotated around an axis varying the pitch to optimize the particular operating condition."

How do you think "variable operations conditions are encountered"?

It means the operator is asking for more or less power through "throttle input"

If the operator wants less power, he/she would decrease the fuel flow through "throttle input". Once the fuel flow is low you can't have too much air in the combustion chamber as the mixture would be too lean and you can flame out the engine. In that situation VIGV would come into action and increase their angle so that air going in to the compressor would take longer to get to the combustion chamber (in layman's term) and in mean time some valves woild open and dump the excess air from the compressor in order to ---wait for it-- "optimize the particular operating condition."

Taken from your post again.

Mate, if after reading that patent your understanding of 'operating condition' is 'throttle input from the pilot', then you need a course in basic English literacy. I could look up more things to debunk your incredible interpretation, but at this point I do not believe I am talking to an expert anyways.

 

[Talon]

20 sqn with pg acting as mini ocu for pg has moved to mm Alam ( Allan new paf book) base not sure why would 18 continue with f-7s if the aircraft are on borrowed life extensions

Anyway guessing here 18 will re eqpt with jf PGS will take over full time ocu ie 20 sqn all pilot will got to 20 ocu and 22 ocu after k-8 no 1 sqn

A year or two later they move to sqn 14 running f-16 ocu and 26 sqn jf ocu

Yeah No 20 moved to m m alam in 2014...but No. 20 had only three FT7s one of which crashed taking life of FO Maryam reducing the numer to 2 and that aint enough for ocu...No. 20 is a proper fighter squadron,its highly unlikely it will be converted to OCU...being a mini ocu means they only have 3-4 trainees per course.

 

[khanasifm]

Yeah No 20 moved to m m alam in 2014...but No. 20 had only three FT7s one of which crashed taking life of FO Maryam reducing the numer to 2 and that aint enough for ocu...No. 20 is a proper fighter squadron,its highly unlikely it will be converted to OCU...being a mini ocu means they only have 3-4 trainees per course.

18 and 19 had 3-4 ft7p and rest all were single seaters each sqn also had 1-2 ft7p total number of ft ordered with all f7 were around 15 and pg around 8-9 I think

Few years ago older Chinese ft7p were gifted

Bottomline paf history tells you about F7 life left especially ft7

Anyway as I said I am guessing here may be would ask next time I come across someone

 

[volatile]

VIGV responds to pilots throttle input. It has nothing to do with what happens to air before the engine. This whole thing started because of black smoke debate

please elaborate more sine black smoke is refered to as incomplete combustion or black carbon now incomplete combustion is result of Air i.e O2 and fuel it self ,so either the fuel used in RD93 needs little refinement or air intake can better solve this problem one of the reasons for smoke is aeroplane operations at various profiles like speed ,turns

 

[BATMAN]

please elaborate more sine black smoke is refered to as incomplete combustion or black carbon now incomplete combustion is result of Air i.e O2 and fuel it self ,so either the fuel used in RD93 needs little refinement or air intake can better solve this problem one of the reasons for smoke is aeroplane operations at various profiles like speed ,turns

You are correct, its the fuel type and its combustion, which result /lead to dark oil stains at exhaust/ air bleeds.

 

[MastanKhan]

Be patient. These are friends/enthusiastic junior members who want to learn.

Hi,

The problem with these ' enthusiaistic ' is that they don't want to learn---.

To learn---you have to ASK---to ask---is " beneath " many---.

 

[Sinnerman108]

The point of contention is whether RD-93 has variable inlet guide vanes or not.

There are two types of guide vanes, static and variable.
The first row is mostly static guide vanes,
which may be followed by variable rows.
and then the last row is static again, before compressed air goes in the combustion tubes.
The function of variable guide vanes, is primarily to stop the compressor blades from stalling
as well as to provide throttle control ( to an extent )
The picture you are showing is not of guide vanes.

@messiach
Can you arrange a RD93 picture with the ring actuators,
that will kill the point.
I have not seen one up close.

 

[CriticalThought]

There are two types of guide vanes, static and variable.
The first row is mostly static guide vanes,
which may be followed by variable rows.
and then the last row is static again, before compressed air goes in the combustion tubes.
The function of variable guide vanes, is primarily to stop the compressor blades from stalling
as well as to provide throttle control ( to an extent )
The picture you are showing is not of guide vanes.

@messiach
Can you arrange a RD93 picture with the actuators,
that will kill the point.
I have not seen one up close.

Many thanks. A wonderful explanation. And yes, it would be awesome if we can have a picture of the internals showing the actuators. +1

 

[Sinnerman108]

Many thanks. A wonderful explanation. And yes, it would be awesome if we can have a picture of the internals showing the actuators. +1

The actuator rings are on the outside of the engine.

logically, all Jet engines are to have these actuators,
because the flight envelope is hugely variable,
the speed as well as air pressure is different.
thus the guide vanes are required to compensate for changes
and ensure the engine does not stall.

please elaborate more sine black smoke is refered to as incomplete combustion or black carbon now incomplete combustion is result of Air i.e O2 and fuel it self ,so either the fuel used in RD93 needs little refinement or air intake can better solve this problem one of the reasons for smoke is aeroplane operations at various profiles like speed ,turns

IT is because of all the above.

Unfortunately, there is no simple absolute solution,
all solutions are compromises and this is how engineering works.

Understand this example.

Assume that the engine inlet was adjusted to allow more air, and thus provide more complete combustion

Yeah ?

Now, better combustion will mean that there is more pressure, and more stress in the turbine stage of the engine.
you must understand that the primary constraint in jet engine design is the turbine stage of the engine.
Our present offerings of materials just cannot cope with the extreme stress.

 

[CriticalThought]

The actuator rings are on the outside of the engine.

logically, all Jet engines are to have these actuators,
because the flight envelope is hugely variable,
the speed as well as air pressure is different.
thus the guide vanes are required to compensate for changes
and ensure the engine does not stall.



IT is because of all the above.

Unfortunately, there is no simple absolute solution,
all solutions are compromises and this is how engineering works.

Understand this example.

Assume that the engine inlet was adjusted to allow more air, and thus provide more complete combustion

Yeah ?

Now, better combustion will mean that there is more pressure, and more stress in the turbine stage of the engine.
you must understand that the primary constraint in jet engine design is the turbine stage of the engine.
Our present offerings of materials just cannot cope with the extreme stress.

But the problem has been solved in Western engines. We need to increase our expertise in metallurgy.

 

[Sinnerman108]

But the problem has been solved in Western engines. We need to increase our expertise in metallurgy.

NO
even the western engines are now at the limit of technology and material sciences.
The materials being used in the turbine stage cannot withstand the extreme heat and stress
without air cooling and ceramics they will collapse in 5 mins or less.

What the western engines do very well, is use software enabled electronics that dynamically
adjusts operational parameters.

going beyond 2700 C is next challenge.

At least I am not aware of any metal or alloy that can take us there.

 

[Advocate Pakistan]

What is the flame below the aircraft at 3:55-3:56 mark just behind the rear landing gear? Is it normal, haven't observed anywhere else. Or is it specifically Mig 29 or Rd-33. but if it's the engine, why isn't that flame there in JF-17 as it has the derivative of same engine.