Missile contrails

[Jazz_44]

We all know that a jet engine aircraft will start to develop contrails at certain altitude, the exact altitude varies based on atmospheric conditions. Will a missile launched off a 'contrailing' aircraft should display similar contrails? Does that depend on the missile's motor type i.e low-smoke, smokeless etc.?

 

Thanks

[Harlikwin]

You can see smoke on some SAMs when they launch. SA8 has smoke on launch for sure.

[Jazz_44]

Yes, that's true, but it's because they launch from the ground. I'm talking about aircraft launching missiles when they are in high altitude, and you can see their engine's contrails

[GTFreeFlyer]

Yes, that's true, but it's because they launch from the ground. I'm talking about aircraft launching missiles when they are in high altitude, and you can see their engine's contrails

 

 

 

I think you answered your question in your first post. Different engines. Contrails form with the correct combination of air pressure, temperature and humidity. The exhaust from an air-breathing turbojet/turbofan is vastly different than solid/liquid propulsion missles. Your air-breathing engines have very hot and high pressure air coming out of them that rapidly expands and cools down. Fill up a balloon with your warm breath and pop it outside where the air is cool and you’ll see a quick “cloud” appear. It’s thermodynamics at work.

[Jazz_44]

Thanks for the answer! So basically any rocket motor should not leave contrails (besides its own smoke) at altitude. I guess DCS models that correctly.

[XtraChrisP]

That's probably closer to the truth. Also note that the burn time for A/A missiles is typically measured in seconds, so it's not like they're leaving a trail of smoke behind them for the entire time of flight

[Worrazen]

If they're intermittently firing up the rocket/motor during flight for course correction then slight plumes of smoke should be seen where applicable, like the puff you see when you turn down or up the throttles on an aircrat, including a trail and/or a contrail for the duration if applicable.

 

 

If the puffs are substantial then this could be a visual indicator, but this has to be research, it may be complicated as it's not something the military would go out and test every possible environmental condition and probably not logged and focused on by the pilots, plus, they can't even see the whole course of the missles as they're not suppose to follow and watch it, so it's tricky, eventually it may be that DCS would have something that reality doesn't know about, but it would take some pretty good conclusion, not sure what is the policy on that, for example if we have a number of other evidences and sources in which it can be guessed then that could replace a hard-evidence actual missile test data or similar.

 

 

 

The A/G missiles would be the ones who's fire time is the lowest, A/A have to also go climb up if necessary, can they do that if all missile fuel was spent before ?

 

 

 

Anyway I fired a lot of Mavericks and I think they did have a trail in the beginning, or at least the engine exhaust, but I forgot exactly.

Edited March 1, 2019 by Worrazen

[Py]

Almost all missiles use a solid rocket motor, once you light it it will burn for a certain time then it's done. The missiles can't turn it on and off, they must rely on the energy from the initial burst of thrust.

[AeriaGloria]

Contrails are caused by water freezing in the air. I would assume that water isn't present in a non air breathing motor, but that's an assumption.

[streakeagle]

It isn't a matter of water being present in a non air-breathing motor, but what effect does the rocket exhaust pressure and temperature have on the surrounding air and its existing water vapor (humidity)? Hot gases are hot gases whether they are produced by a jet or a rocket. Rocket exhaust should be hotter and/or higher pressure since it moves missiles at Mach 2 to Mach 4+ speeds at high altitudes. So what temperatures/pressures exist at a missile's exhaust and at what temperatures/pressures/humidities do condensation/contrails form?

[GTFreeFlyer]

Also, while the exhaust is a likely place, it isn’t the only one. Look at what happens when a heavy is landing with full flaps on a humid day. The high pressure air under the flap that makes its way outboard along the flap suddenly escapes at the inboard end of the aileron, expands and cools, and creates a short-lived contrail, mostly a spinning vortex.

[AeriaGloria]

Good points!

[streakeagle]

Temperature, pressure, and humidity => condensation => contrails.

[Smee]

There is apparently a 'smokeless' variant of the AIM-54 with the new F-14 module from Heatblur.

 

AIM-54C, I believe.

 

Good hunting.

[Luzifer]

There is apparently a 'smokeless' variant of the AIM-54 with the new F-14 module from Heatblur.

 

AIM-54C, I believe.

 

Smoke and contrails are different and independent things.

[Hammer1-1]

Depending on the fuel thats used, rockets may or may not smoke in the upper atmosphere. Some missile engines use smokeless fuel; other older missiles like the Phoenix A will smoke while the AMRAAM D will not. As far as contrails go, something has to bind the water molecules together in order to generate it. Cold damp air mixing with hot dry air will give you some contrails, as well as pressure variations in the atmosphere. Again, you have to have a medium to generate contrails; you wont see any contrails in a dry atmosphere do to a lack of water vapor.

Edited March 2, 2019 by Hammer1-1

[Dehuman]

Hot air can hold (absorb) more water than cold air. When Hot air is cooled below the temperature it can continue to hold that water it is forced to condense out.

 

In non-air breathing motors the water exhaust can be a product of the fuel oxidization.

[Dehuman]

For example the main products from CL-20 fuel (C6H6N6(NO2)6) will be carbon dioxide, nitrous oxide and water.

 

Any of that water that cannot be absorbed by the air will remain as water vapour. If the air is below 0 it will freeze and you get a contrail.

Edited March 2, 2019 by Dehuman

[Weta43]

Missile contrails (as opposed to smoke trails)

[Nealius]

AIM-120 live fire around 4:50 in this video as well. I don't remember getting contrails like that at altitude last time I launched an AMRAAM in DCS, but it's been a few weeks since I last fired one.

 

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[nighthawk2174]

Yes missile contrails are not modeled in DCS, missile smoke is but not missile contrails.

[Vatikus]

Here are two pictures I've posted in other similar thread:

 

 

 

[drPhibes]

Here's a close-up of a AIM-120 launch, with contrails:

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[falcon_120]

Please ED, put this higher up in the list.

 

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