SamuraiBlue
Captain
As I said it's a possibility but It's usually on the side of the engine and never in the center.
Chinese Engine Development
- Thread starter jackbh
- Start date
As I said it's a possibility but It's usually on the side of the engine and never in the center.
So you mean the Su-27s and J-11s have more powerful engines than the F-15? What about fuel efficiency? I know F-15s have combat radius of 1,800(E model) to 1,900km(earlier C model), but Su-27s and Su-30s only have 1,500km.
SamuraiBlue
Captain
Just compare the specs of the two engines.
Saturn AL-31
Maximum
74.5 kilonewtons (16,700 lbf) dry thrust
122.58 kilonewtons (27,560 lbf) with afterburner
Thrust-to-weight ratio:
4.77:1 (dry),
7.87:1 (afterburning)
Pratt & Whitney F100
Maximum :
14,590 pounds-force (64.9 kN) military thrust,
23,770 pounds-force (105.7 kN) with afterburner
:
7.4:1
Fine to disagree. But remember, he just mentioned it as a possibility...not that it was definitely the cause.
I guess we are talking about the late 1970's era F-15Cs then. I know the F-15E uses a much more powerful engine, one with 29,000 pounds-force, but still spits yellow fire rather than blue ones. Maybe Russian engines just happen to have afterburners that tolerate slightly higher temperatures, and the Chinese designers based their designs on 1980's Soviet technology? However, from most sources I have read, it seem like China got its engine core technology from civilian CFM engines, and then militarize them. Please tell me more...I have never taken a physics class. Only four biology classes and two chemistry ones.
by78
General
I'm not saying that it's not a possibility. To me, it's simply improbable and unlikely.
thunderchief
Senior Member
Nope
Latest version with 129 kN full afterburner and white-bluish flame, from Wikipedia 
by78
General
I suspect flame color has a lot to do with lighting conditions and the angles at which the photos/videos are taken
Blue flames appear less opaque than red, and ambient light therefore makes them less visible. If you notice many photos of engines spitting out red are taken during daytime against a blue sky or in bright sun light, which obscures the blue component and accentuates the red.
I suspect that many modern Western turbofan engines on full burner have flames that are red/yellow toward the center but blue on the outside, and depending on the aforementioned conditions, they may appear yellow/red, or blue, or both.
Now see the below videos for yourself. Both are GE F414 turbofans doing full burner, and yet one of them appears to spit red during daytime and the other spits blue against a dark background.
Lastly, there are many other factors involved here. Accuracy of camera sensors, exposure levels, and post-processing of photos/videos can greatly affect the color and hue of flames. All of this is in addition to factors mentioned by others (e.g. chemical composition of the jet fuel, etc).
Blue flames appear less opaque than red, and ambient light therefore makes them less visible. If you notice many photos of engines spitting out red are taken during daytime against a blue sky or in bright sun light, which obscures the blue component and accentuates the red.
I suspect that many modern Western turbofan engines on full burner have flames that are red/yellow toward the center but blue on the outside, and depending on the aforementioned conditions, they may appear yellow/red, or blue, or both.
Now see the below videos for yourself. Both are GE F414 turbofans doing full burner, and yet one of them appears to spit red during daytime and the other spits blue against a dark background.
Lastly, there are many other factors involved here. Accuracy of camera sensors, exposure levels, and post-processing of photos/videos can greatly affect the color and hue of flames. All of this is in addition to factors mentioned by others (e.g. chemical composition of the jet fuel, etc).
Last edited:
thunderchief
Senior Member
@by78 It is quite possible that daylight masks some of the light frequencies coming from the engine, but keep in mind that actual planes during takeoff seldom use full afterburner . Therefore, temperature of the gasses would be lower and color shifted towards red .
Here is Tu-22M with its massive 247 kN engines, burning blue even during the day
Here is Tu-22M with its massive 247 kN engines, burning blue even during the day