J-20 5th Generation Fighter VII

[ZeEa5KPul]

Even when the J-20 gets WS-15 it will probably still be smokey.

Smoke is just a fact of life I guess. Hoping all jets will use smokeless plasma thrusters before I kick the bucket.

You want to see smoke? Check out a kerolox gas generator rocket engine.

It's certain that the WS-15 (and any engine that works by combusting kerosene) will be transiently smokey in certain flight regimes. Hydrocarbon chains at high temperatures in oxygen poor conditions form polymers, just a fact of life.

On another note, it's strange how perceptions change over time. When I first saw the J-------20, I thought "why is that plane so long?" Now that I see the F-22 again, I think "why is that plane so stubby?"

 

[sinophilia]

I saw this recently. This one is even more obvious, starting from 3:00 (and 9:00, 9:40), you can clearly see lots of brown smoke.
View attachment 77935

Wow this is a great example to illustrate the difference (or really lack thereof). Didn't even know this could come from an F-22. Thanks for helping resolve my ignorance.

 

[Blitzo]

Jeez page 330 and we're back to smoke? What's next, length and dimensions?! (Yea I need coffee....)

Considering we've never had pictures of meaningful smoke from J-20s engines before prior to this airshow, I think it is a reasonable topic of discussion and curiosity.

And the videos and pictures posted in the last page or so are excellent for showing how common it actually is even among other 5th generation fighters.

 

[ZeEa5KPul]

 

[Mohsin77]

Hoping all jets will use smokeless plasma thrusters before I kick the bucket.

Tactically, I'd worry more about contrails than smoke.

Here's an old source which covers both:

Fighter Combat: Tactics and Maneuvering,
Robert L. Shaw, United States Naval Institute

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"Along with the techniques already discussed, there are some other practical points worth mentioning about becoming invisible and staying that way during a pitch-back. For instance, the energy fighter pilot should be aware of the contrail level. Depending on air temperature and humidity, the water vapor in the exhaust of both jet and reciprocating engines may condense to form a vapor trail that can turn a small invisible fighter into an airliner, visible for a hundred miles. This is generally a high-altitude phenomenon that can be predicted fairly accurately by meteorologists. A more accurate determination of the contrail level can be made prior to engaging by checking for a contrail during a climb. It should be recognized, however, that the contrail level also is sensitive to exhaust temperature, so this check should be made at combat power when practical. For instance, jet contrails may appear at different altitudes depending on whether or not the fighter is using afterburner. The contrail most often becomes a factor approaching the top of a pitch-back in a high-altitude fight. The contrail level may require completing the vertical maneuver as quickly as possible rather than continuing a zoom to the highest attainable altitude." p169

"Other visual considerations in the approach are contrails and engine smoke. Little needs to be said about the effect of contrails on visual detection range, since probably everyone has seen airliners a hundred miles away. The contrail level simply must be avoided. Smoke can also be a very serious problem, as heavy smoke trails can be seen for twenty to thirty miles under some conditions, especially against light backgrounds. In addition to selecting a darker background and engine operating conditions that minimize smoke (discussed in a previous chapter), avoiding collision-course intercept geometry can also help. A fighter on a collision course tends to remain in one spot in the sky when viewed by the enemy, so the smoke trail appears to be concentrated behind the fighter and becomes darker and more noticeable. An early displacement turn away from the bogey's flight path, and stern-conversion geometry, can make the trail appear thinner and make it more difficult to see against lighter backgrounds. " p383

 

[TomSellinger]

No more J-20 performances. Better luck next year. Hopefully COVID would be over by then.

Won't be over next year because covid-19 is endemic outside China. Unless China does not allow a foreigner in, like North Korea.

 

[by78]

A few more from Zhuhai...

 

[by78]

 

[by78]

 

[banjex]

Are these nacelles the stealthiest the J-20 will get? Is it likely to get further LO improvements when the WS-15s are deployed?