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Old 15th February 2013, 14:45   #121
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Default Re: Aero India 2013 - Pictures

Thanks H4wk for those videos. Seriously, I wish the organisers avoided the background music too! It just "s***s" !!!

The performance by Rafael seems mindblowing! I am sure our IAF pilots are going to enjoy their stint flying the french beauty.
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Old 15th February 2013, 18:45   #122
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Thanks H4wk for those videos. Seriously, I wish the organisers avoided the background music too! It just "s***s" !!!

The performance by Rafael seems mindblowing! I am sure our IAF pilots are going to enjoy their stint flying the french beauty.
Thanks Arvind! There's more to come; not finding time to edit and upload
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Old 15th February 2013, 21:01   #123
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Default Re: Aero India 2013 - Pictures

In the below picture the flame in one engine is blue and yellow in the other. Been wondering how it is so from the time I have seen it, can some body ( Alphakilo ? Neel ? ) explain

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In the below picture, one engine has blue flame and the other yellow, can some one shed some light on why it is so ?
Attachment 1049842

Both the engines have blue flame
Attachment 1049843
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Old 15th February 2013, 23:14   #124
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^^At around 4:20 you get to see one of the most aggressive negative G turns that I have seen a fighter do in quite a while!
Practically every boy had once dreamed of becoming a fighter pilot. If you could start a dedicated thread on life of a fighter pilot, I am sure it would make very interesting reading. It could deal with mechanicals, technical aspects of he machines, training, demands of being a fighter pilot, role, etc, etc.
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Old 16th February 2013, 07:33   #125
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In the below picture the flame in one engine is blue and yellow in the other. Been wondering how it is so from the time I have seen it, can some body ( Alphakilo ? Neel ? ) explain
The basic vapor color is white which is produced by injecting diesel into the hot engine exhaust. Temperature is around 400 - 450oC and the diesel vaporizes immediately. The different colors are produced by mixing a dye into the diesel.

Most of these display team plane have special pods for the diesel and the dyes. Pilot controls the release by means of a different button for each color.

The diesel and the dyes are limited so display teams will carefully plan out how and when and for how long they produce smoke of which color during the display.

Jeroen
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Old 16th February 2013, 07:54   #126
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Default Re: Aero India 2013 - Pictures

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The basic vapor color is white which is produced by injecting diesel into the hot engine exhaust...Jeroen
I dont' think that answers the question. From whatever little i've read, low temperatures tend to produce no light or reddish-orange light but high temperatures produce progressively bluer light.

But how come both the colors show up in a twin engine plane at the same time? Are there dedicated controls for each mill?
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Old 16th February 2013, 08:24   #127
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I dont' think that answers the question. From whatever little i've read, low temperatures tend to produce no light or reddish-orange light but high temperatures produce progressively bluer light.

But how come both the colors show up in a twin engine plane at the same time? Are there dedicated controls for each mill?
Sorry, you're quite right. I was looking at some of the other pictures where the planes are trailing smoke. That's done by injecting diesel and or dye.

I'm not sure about the phenomena you're referring to. Could be maybe the difference between being on afterburner or not. Not sure why there would be a difference between the two engines. Other than I do know that there could be a little delay between the afterburners coming in. Meaning one engine could be lit slightly earlier than the other. But I leave it to the real jet pilots to comment on. I'm just a GA pilot. Strictly propellors, and only one at the time! Challenging enough for me.
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Old 16th February 2013, 13:51   #128
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Default Re: Aero India 2013 - Pictures

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Originally Posted by SandyX View Post
I dont' think that answers the question. From whatever little i've read, low temperatures tend to produce no light or reddish-orange light but high temperatures produce progressively bluer light.

But how come both the colors show up in a twin engine plane at the same time? Are there dedicated controls for each mill?
(@neel and @sheelz correct me if i am wrong somewhere)
Yes, multi-engined jets have individual throttle controls. (@Neel365 and @sheelz??? (well you technically fly a single-engine jet sir just joking!)

Just to show an example: The Throttle and Main control stick (this is how it could look like!) of the FGFA (in laymans terms - the stealth jet from Russkis). The one on the left is the main control stick and the one on the right is the throttle control stick. It has individual throttle controls for individual engines. (the twin engined a/c's are designed to fly normally even if one of their engines fail)

(some russian language experts (any FSB agents or former KGB operatives can also help) please translate)


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But I leave it to the real jet pilots to comment on. I'm just a GA pilot. Strictly propellors, and only one at the time! Challenging enough for me.


Btw answering the question of flame colours: We all have done Bunsen Burner test in our school days!!! Complete combustion - blue flame, incomplete combustion - orange flame!

Now for some fun: Why I like to call MKI the "Rambha"

http://www.youtube.com/watch?feature...=-hq_RTaThNI#!

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Old 16th February 2013, 18:15   #129
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In the below picture the flame in one engine is blue and yellow in the other. Been wondering how it is so from the time I have seen it, can some body ( Alphakilo ? Neel ? ) explain
Quote:
Originally Posted by SandyX View Post
From whatever little i've read, low temperatures tend to produce no light or reddish-orange light but high temperatures produce progressively bluer light.But how come both the colors show up in a twin engine plane at the same time? Are there dedicated controls for each mill?
The flame that you see in the pictures are the afterburner flames. More on afterburners here: http://en.wikipedia.org/wiki/Afterburner . The flame colour will depend on the efficiency of the afterburner system as brought out by Sandy X with a more efficient afterburner system producing a hotter and hence bluer flame. The Su 30 is powered by the Al 31 family of engines which are considered to be highly efficient and hence you will generally see blue afterburner flames in this aircraft. During harsh maneuvering however, the aircraft operates at very high Angles Of Attack (AOA) because of which a certain ammount of engine intake blanking can take place leading to a drop in engine efficiency and hence a more orange flame. In case of multi engine fighters, both the intakes may be operating at different AOA and hence blanking conditions and hence you might see a difference in the flame colour in the two engines.

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(@neel and @sheelz correct me if i am wrong somewhere)
Yes, multi-engined jets have individual throttle controls. (@Neel365 and @sheelz??? (well you technically fly a single-engine jet sir just joking!)
While traditionally multi engine aircraft had seperate throttles for each engine, in modern fighters, the throttle simply acts a a thrust demand lever which is connected to the Engine Control Computer which independently controls the engines. In such fighters there is a single throttle as in the Rafale.
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Ok, we want to see some big flames coming out of a jet engine??

It doesn't get any better than this:

The American F111 was capable of doing a so called dump and burn. Basically they dumped fuel which was subsequently ignited by the engines exhaust. I doesn't add any power to the plane, but it sure does look spectacular!

Enjoy:



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Originally Posted by neel385 View Post
While traditionally multi engine aircraft had seperate throttles for each engine, in modern fighters, the throttle simply acts a a thrust demand lever which is connected to the Engine Control Computer which independently controls the engines. In such fighters there is a single throttle as in the Rafale.
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Interesting, I did not know that. So I guess any problems with one of the engine is all dealt with through automation? I guess asymmetric thrust is not a big deal on these jets as both engines are so close to the centerline of the plane anyway.

But still, could you for instance run one engine on idle and the other on full power? Maybe I'm just thinking to much from a GA/commercial airline pilot persepctive where on a twin that would still be the preferred option over running just one engine. If one engine runs hot, you throttle back, but as long as you can keep it running you keep it running.

Jeroen

Last edited by GTO : 18th February 2013 at 15:33. Reason: Merging both your posts.
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Old 16th February 2013, 18:51   #130
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Interesting, I did not know that. So I guess any problems with one of the engine is all dealt with through automation? I guess asymmetric thrust is not a big deal on these jets as both engines are so close to the centerline of the plane anyway.
Most of the modern generation fighters are Fly by Wire which further makes the job of handling asymmetric thrust easier.

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But still, could you for instance run one engine on idle and the other on full power? Maybe I'm just thinking to much from a GA/commercial airline pilot persepctive where on a twin that would still be the preferred option over running just one engine. If one engine runs hot, you throttle back, but as long as you can keep it running you keep it running.
Jeroen
In a fighter with both the engines close to the centerline, I do not really see the requirement, though in older multiengine fighters, pilots had to manage throttles separately, specially when the thrust of both the engines were not the same resulting in yaw. In modern fighters, the thrust of both are matched by the Engine Computer(ECU). In certain Thrust Vectored Aircraft, the ECU is known to adjust the thrust from both the engines separately in consonance with the pilots manoeuvre demands.

In the case one engine malfunctions, the ECU will take over and try to recover the engine, failing which the engine will be shut down with associated warnings to the pilot. Does it really matter if the pilot does the job manually as with two throttles or the ECU does the work for him?
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Old 16th February 2013, 21:52   #131
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Most of the modern generation fighters are Fly by Wire which further makes the job of handling asymmetric thrust easier.

In a fighter with both the engines close to the centerline, I do not really see the requirement, though in older multiengine fighters, pilots had to manage throttles separately, specially when the thrust of both the engines were not the same resulting in yaw. In modern fighters, the thrust of both are matched by the Engine Computer(ECU). In certain Thrust Vectored Aircraft, the ECU is known to adjust the thrust from both the engines separately in consonance with the pilots manoeuvre demands.

In the case one engine malfunctions, the ECU will take over and try to recover the engine, failing which the engine will be shut down with associated warnings to the pilot. Does it really matter if the pilot does the job manually as with two throttles or the ECU does the work for him?

I don't think fly by wire makes handling asymmetrical thrust easier perse. Compare the engine our procedure for an Airbus 320 (fly by wire) against a Boeing 767 (non fly by wire) and you will find they are near identical.

Engine out scenario's are first and foremost recovered by flight controls, i.e. rudder, ailerons and possibly elevators. And subsequently dialed out by trim adjustments. Any 1980's auto pilot (i.e. Honeywell series) has already been able to do so. At least on GA planes and commercial airliners.

When you fly manually, you go through the same motion, fly by wire or not. In such a scenario, ie engine out, hand flying, and with fly by wire, you could envisage that the computers once they detect an engine malfunction occurs, start dialing in rudder, elevator, aileron to trim out any yaw. But I would think that it is counter intuitive for a pilot flying manual. This could lead to the pilot overcompensating,and could lead to Dutch roll or worse.

So it's more about the design philosophy than what is technically feasible.

I fly with autopilots and I'm fully aware on how the autopilot trims my plane when I engage it. But when I fly manually I don't want any computer overriding my control inputs.

My question was more about in planes such as the Rafale that have only one thrust lever for two engines how do you control engines separately in emergency scenario's? As I said, I'm probably slightly biased as I have only experience in GA aircraft. And I have a surprising amount of hours on the 747-400 Full Motion crew training Simulators of Lufthansa and Cargolux.

On aircrafts losing an engine it is not only about losing the associated thrust. You also lose the electrical, hydraulical and pneumatic power provided by that engine. On a twin engine jet these systems will be fully redundant, and I assume in fighters one engine will provide sufficient electrical, hydraulic and pneumatic power to fly the plane more or less normally.

There are many engine problem scenario's where running the engine at reduced power settings or even at idle, are preferred to shutting down all together. Purely for safety measure. What I got drilled into me by Lufthansa flight school is:
- First of all, deal with the emergency and stabilize the situation
- Two, plan ahead on what would happen if the next failure occurs.

So keeping one engine running even on idle is a good preventive measure in case something happens to engine number two and you might have to shut it down all together. To a large extent you can program this. But under these circumstances, it comes down to pilot discretion and decision. Maybe run an engine into the ground, but maintain standby electrical and hydraulic power. And for that you need manual control of the engine, manual monitoring of the engine parameters. So how do you do that in the Rafale, or is it all programmed into the flight management computers?

Jeroen
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Old 17th February 2013, 01:19   #132
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I don't think fly by wire makes handling asymmetrical thrust easier perse. Compare the engine our procedure for an Airbus 320 (fly by wire) against a Boeing 767 (non fly by wire) and you will find they are near identical.
I was specifically referring to modern generation fighters which are generally unstable in (at least) one channel where the FBW makes things a lot easier.

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Engine out scenario's are first and foremost recovered by flight controls, i.e. rudder, ailerons and possibly elevators. And subsequently dialed out by trim adjustments. Any 1980's auto pilot (i.e. Honeywell series) has already been able to do so. At least on GA planes and commercial airliners.
Agreed.

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When you fly manually, you go through the same motion, fly by wire or not. In such a scenario, ie engine out, hand flying, and with fly by wire, you could envisage that the computers once they detect an engine malfunction occurs, start dialing in rudder, elevator, aileron to trim out any yaw. But I would think that it is counter intuitive for a pilot flying manual. This could lead to the pilot overcompensating,and could lead to Dutch roll or worse.
The overcompensation will not happen because the autopilot will restrict the pilot inputs so as to ensure that the aircraft stays within safe parameters. So depending on the flight situation the autopilot will either go into G limit or AOA limit mode as per the design specifications and ensure safety of the platform. In fact, in some modern fighters, the autopilot is always engaged and you momentarily disengage the autopilot to give manual inputs. Watch any video of a F 18 takeoff and you will see that the pilots hands are off the controls during the take off, and that too from a carrier!


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My question was more about in planes such as the Rafale that have only one thrust lever for two engines how do you control engines separately in emergency scenario's?
I am not qualified on the Rafale so I will not really be able to give you specifics, but, from what I have read, the engine control system obviates the requirement of the pilot to individually control each engine. Exact how? Not sure at this stage.

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On a twin engine jet these systems will be fully redundant, and I assume in fighters one engine will provide sufficient electrical, hydraulic and pneumatic power to fly the plane more or less normally.
Correct.

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So how do you do that in the Rafale, or is it all programmed into the flight management computers?
Again, not qualified on the Rafale, but, from what I have been able to read and having interacted with a few guys who have flown it, the Rafale has a very advanced man machine interface where the aircraft practically flies itself leaving the pilot to carry out the various system management tasks towards mission accomplishment.
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Old 17th February 2013, 08:39   #133
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I am not qualified on the Rafale so I will not really be able to give you specifics, but, from what I have read, the engine control system obviates the requirement of the pilot to individually control each engine. Exact how? Not sure at this stage.
Just wondering, are you a pilot yourself, if so, what do you fly?

Jeroen
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Old 17th February 2013, 14:22   #134
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This thread is very interesting. Please continue the discussion.
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Old 17th February 2013, 15:53   #135
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Just wondering, are you a pilot yourself, if so, what do you fly?

Jeroen
I've flown the MiG 21, MiG 27, Mirage 2000 and instructed on the HPT 32, HJT 16 and the HAWK AJT.
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