JF-17 Thunder Multirole Fighter [Thread 7]

[Safriz]

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.

Almost all Russian made jest engine throw a flame just before starting.

Typhoon starting. No flame but the smoke.

 

[ashok321]

Almost all Russian made jest engine throw a flame just before starting.

Typhoon starting. No flame but the smoke.

Watch this and come back to me:

 

[Sinnerman108]

Almost all Russian made jest engine throw a flame just before starting.

Typhoon starting. No flame but the smoke.

&& @Advocate Pakistan

Guys come on, you have to do some learning yourself too.

I will give you a hint.
Miig29 has an APU, auxiliary power unit
and Typhoon is starting without it.

Once you figure out, what APU does, and what is bleed air
then you will figure this out too.

 

[Safriz]

&& @Advocate Pakistan
Guys come on, you have to do some learning yourself too.

I will give you a hint.
Miig29 has an APU, auxiliary power unit
and Typhoon is starting without it.

Once you figure out, what APU does, and what is bleed air
then you will figure this out too.

good point. The APU exhaust on typhoon is just above the wing and chunks out a lot of smoke and also flames at times. So APU it is then?

Typhoon APU exaust with soot. Always looks bad when we are taking hi res pictures of the jet.

Watch this and come back to me:

Likewise MI-17 turbo shaft chucks out lots of flames at start-up, seen myself, but here its not doing it.

 

[Advocate Pakistan]

&& @Advocate Pakistan

Guys come on, you have to do some learning yourself too.

I will give you a hint.
Miig29 has an APU, auxiliary power unit
and Typhoon is starting without it.

Once you figure out, what APU does, and what is bleed air
then you will figure this out too.

Thank you for the information.
I agree we should learn ourselves too, but newbies like me usually don't know what resources to rely on and what to refrain from. That's why teachers are important.

 

[Sinnerman108]

good point. The APU exhaust on typhoon is just above the wing and chunks out a lot of smoke and also flames at times. So APU it is then?

Typhoon APU exaust with soot. Always looks bad when we are taking hi res pictures of the jet.

NO
Here s another hint. See how F-16 is started by ground crew in Iraq. ( Old Video )

Just to help you,
The Jet engine is basically and set of blades and fans that perform Fresh Air in, Burnt air out.
Thus to start such a engine, the steps are as follows:
Start the electrical systems
Spin the Jet engine's shaft to the correct RPM
Introduce fuel in the primary fuel supply circuit
Await ignition , and RPM threshold
Cut off fuel supply to primary circuit, and switch to secondary circuit.

Now, in the above puzzle, one step is missing.
That is what you guys have to figure out.

 

[Safriz]

NO
Here s another hint. See how F-16 is started by ground crew in Iraq. ( Old Video )

Just to help you,
The Jet engine is basically and set of blades and fans that perform Fresh Air in, Burnt air out.
Thus to start such a engine, the steps are as follows:
Start the electrical systems
Spin the Jet engine's shaft to the correct RPM
Introduce fuel in the primary fuel supply circuit
Await ignition , and RPM threshold
Cut off fuel supply to primary circuit, and switch to secondary circuit.

Now, in the above puzzle, one step is missing.
That is what you guys have to figure out.

Nop, cant figure out.
You tell us. I have worked on turbo shafts , but we used external high pressure air to initiate the engine start.

 

[Advocate Pakistan]

NO
Here s another hint. See how F-16 is started by ground crew in Iraq. ( Old Video )

Just to help you,
The Jet engine is basically and set of blades and fans that perform Fresh Air in, Burnt air out.
Thus to start such a engine, the steps are as follows:
Start the electrical systems
Spin the Jet engine's shaft to the correct RPM
Introduce fuel in the primary fuel supply circuit
Await ignition , and RPM threshold
Cut off fuel supply to primary circuit, and switch to secondary circuit.

Now, in the above puzzle, one step is missing.
That is what you guys have to figure out.

so the APU is like a small battery that provides for the initial ignition and certain critical systems to come online without requiring to actually ignite the engine, just as the car battery provides for lights, sound system etc without requiring to start the car.

 

[Sinnerman108]

so the APU is like a small battery that provides for the initial ignition and certain critical systems to come online without requiring to actually ignite the engine, just as the car battery provides for lights, sound system etc without requiring to start the car.

Nop, cant figure out.
You tell us. I have worked on turbo shafts , but we used external high pressure air to initiate the engine start.

Yes, extremely high pressure air is correct,
See the F-16 carries two shots of hydraulic accumulators with it, which have enough pressure to crank up the engine.
if these two fail, then only an APU is requested. ( Same process in the EuroJet ).

 

[volatile]

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.

your explanation is not inline with chemical composition in fuel mechanics more O2 is pumped to get complete combustion not to do more combustion since the chamber is designed to withstand the design combustion the perfect example if you recall the honda IDSI engine in City 2003 to 2009 which used sequel ignition system means that it employs two stage combustion decided by computer based on the throttle needs and in this the added spark plugs or ignition source were added for each chamber 2 means total 8 for 4 cylinder car the narration explained above cant be put as facts

EXCESS AIR AND BOILER EFFICIENCY In theory, to have the most efficient combustion in any combustion process, the quantity of fuel and air would be in a perfect ratio to provide perfect combustion with no unused fuel or air. This type of theoretical perfect combustion is called stoichiometric combustion. In practice, however, for safety and maintenance needs, additional air beyond the theoretical “perfect ratio” needs to be added to the combustion process—this is referred to as “excess air.” With boiler combustion, if some excess air is not added to the combustion process, unburned fuel, soot, smoke, and carbon monoxide exhaust will create additional emissions and surface fouling. From a safety standpoint, properly controlling excess air reduces flame instability and other boiler hazards. Even though excess air is needed from a practical standpoint, too much excess air can lower boiler efficiency. So a balance must be found between providing the optimal amount of excess air to achieve ideal combustion and prevent combustion problems associated with too little excess air, while not providing too much excess air to reduce boiler efficiency. Research has shown that 15% excess air is the optimal amount of excess air to introduce into the boiler combustion process. While some boilers have been able to achieve 15% excess air at the top end of a boiler’s firing range, the challenge presents itself at the lower end of the firing range, or below 60% of the boiler’s maximum capacity. In general, most boilers tend to increase excess air requirements as the firing rate of the boiler decreases, leading to lower efficiency at the lower end of the firing range. To complicate matters, most boilers operate on the lower end of the firing range—so selecting a boiler that has low excess air throughout the firing range is important. This will ensure that you are always operating at high efficiencies.

I have put boiler example just to explain my point ,please dont quote such words on combustion

 

[Sinnerman108]

Nop, cant figure out.
You tell us. I have worked on turbo shafts , but we used external high pressure air to initiate the engine start.

@Advocate Pakistan

Hints ..
do you know what is a planetary reduction drive ?
Find out what does it do.

 

[Talon]

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

Asked about 18 sqn conversion...was told as long F7s are active with CCS,No. 18 is gonna operate F7s..

 

[razgriz19]

your explanation is not inline with chemical composition in fuel mechanics more O2 is pumped to get complete combustion not to do more combustion since the chamber is designed to withstand the design combustion the perfect example if you recall the honda IDSI engine in City 2003 to 2009 which used sequel ignition system means that it employs two stage combustion decided by computer based on the throttle needs and in this the added spark plugs or ignition source were added for each chamber 2 means total 8 for 4 cylinder car the narration explained above cant be put as facts

EXCESS AIR AND BOILER EFFICIENCY In theory, to have the most efficient combustion in any combustion process, the quantity of fuel and air would be in a perfect ratio to provide perfect combustion with no unused fuel or air. This type of theoretical perfect combustion is called stoichiometric combustion. In practice, however, for safety and maintenance needs, additional air beyond the theoretical “perfect ratio” needs to be added to the combustion process—this is referred to as “excess air.” With boiler combustion, if some excess air is not added to the combustion process, unburned fuel, soot, smoke, and carbon monoxide exhaust will create additional emissions and surface fouling. From a safety standpoint, properly controlling excess air reduces flame instability and other boiler hazards. Even though excess air is needed from a practical standpoint, too much excess air can lower boiler efficiency. So a balance must be found between providing the optimal amount of excess air to achieve ideal combustion and prevent combustion problems associated with too little excess air, while not providing too much excess air to reduce boiler efficiency. Research has shown that 15% excess air is the optimal amount of excess air to introduce into the boiler combustion process. While some boilers have been able to achieve 15% excess air at the top end of a boiler’s firing range, the challenge presents itself at the lower end of the firing range, or below 60% of the boiler’s maximum capacity. In general, most boilers tend to increase excess air requirements as the firing rate of the boiler decreases, leading to lower efficiency at the lower end of the firing range. To complicate matters, most boilers operate on the lower end of the firing range—so selecting a boiler that has low excess air throughout the firing range is important. This will ensure that you are always operating at high efficiencies.

I have put boiler example just to explain my point ,please dont quote such words on combustion

Combustion chamber in a turbine doesn't need excess air. In fact there are systems in place to prevent exactly that. There are compressor bleed valves that dump air in low speeds as the LP compressor pumps in more air than the rest of the engine can handle. You can't just dump more air in the combustion chamber to improve or do "complete" combustion. Doesn't work that way.

 

[MastanKhan]

Hi,

In the 80's---70's---russian fighter aircraft were smokeless---americans had a lots pf smoke.

So---when Lt Belenko defected with his MIG25 to japan---one of the items was was taken out was the fuel----to be analyzed.

A sample ended up on the lab counter of one of my colleagues---he discussed the process and procedure and how the process was handled a few years ago---which I don't remember---but that resulted in the smokeless engines of those years.

Since the demise of the soviet union---russia does not have that kind of money to upgrade their older engine designs or to process that fuel---

your explanation is not inline with chemical composition in fuel mechanics more O2 is pumped to get complete combustion not to do more combustion since the chamber is designed to withstand the design combustion the perfect example if you recall the honda IDSI engine in City 2003 to 2009 which used sequel ignition system means that it employs two stage combustion decided by computer based on the throttle needs and in this the added spark plugs or ignition source were added for each chamber 2 means total 8 for 4 cylinder car the narration explained above cant be put as facts

EXCESS AIR AND BOILER EFFICIENCY In theory, to have the most efficient combustion in any combustion process, the quantity of fuel and air would be in a perfect ratio to provide perfect combustion with no unused fuel or air. This type of theoretical perfect combustion is called stoichiometric combustion. In practice, however, for safety and maintenance needs, additional air beyond the theoretical “perfect ratio” needs to be added to the combustion process—this is referred to as “excess air.” With boiler combustion, if some excess air is not added to the combustion process, unburned fuel, soot, smoke, and carbon monoxide exhaust will create additional emissions and surface fouling. From a safety standpoint, properly controlling excess air reduces flame instability and other boiler hazards. Even though excess air is needed from a practical standpoint, too much excess air can lower boiler efficiency. So a balance must be found between providing the optimal amount of excess air to achieve ideal combustion and prevent combustion problems associated with too little excess air, while not providing too much excess air to reduce boiler efficiency. Research has shown that 15% excess air is the optimal amount of excess air to introduce into the boiler combustion process. While some boilers have been able to achieve 15% excess air at the top end of a boiler’s firing range, the challenge presents itself at the lower end of the firing range, or below 60% of the boiler’s maximum capacity. In general, most boilers tend to increase excess air requirements as the firing rate of the boiler decreases, leading to lower efficiency at the lower end of the firing range. To complicate matters, most boilers operate on the lower end of the firing range—so selecting a boiler that has low excess air throughout the firing range is important. This will ensure that you are always operating at high efficiencies.

I have put boiler example just to explain my point ,please dont quote such words on combustion

Hi,

You need to keep with the turbine example---. Examples of other types of combustion chambers may confuse the subject matter and understanding the function of the unit in question.

 

[volatile]

Agreed and also read some where correct Sir

Hi,

In the 80's---70's---russian fighter aircraft were smokeless---americans had a lots pf smoke.

So---when Lt Belenko defected with his MIG25 to japan---one of the items was was taken out was the fuel----to be analyzed.

A sample ended up on the lab counter of one of my colleagues---he discussed the process and procedure and how the process was handled a few years ago---which I don't remember---but that resulted in the smokeless engines of those years.

Since the demise of the soviet union---russia does not have that kind of money to upgrade their older engine designs or to process that fuel---

Hi,

You need to keep with the turbine example---. Examples of other types of combustion chambers may confuse the subject matter and understanding the function of the unit in question.

With respect my example was process of combustion and how complete combustion occurs you are right the topic is turbine engines