Prop Aircraft Contrails?

[SWADLER747]

Hi ! Just wondering do/would prop aircraft such as the Dash 8 / ATR etc give off contrails if conditions were right, or is this phenomonon just common to jet powered aircraft.

Obviously the following factors must occur:

1. Freezing temperatures (less than -38'c?) - Correct ???
2. Moist Air

Does anyone have any links to prop aircrafts contrails?

Cheers :p

[RowleyUK]

One would presume so......

Despite the prop on the front, the ATR still uses a turbine style engine and therefore if it was to fly high enough and in the right conditions then i would say - yes you can get contrails.....i stand to be corrected!:E


However, a piston kinda prop wouldnt give the contrails..

[BlueEagle]

Plenty of pictures around of USA bombers in WW2 on daylight raids making contrails!

[cloudcover]

"However, a piston kinda prop wouldnt give the contrails.."

Well, actually...yes they do! Think B-17s high over
europe...:rolleyes:

[HotDog]

B-17s over Europe. See picture here:
http://www.msnusers.com/vmfeitup8j49chjajqlopc37j7/Documents/Pictures%2Fb17%2Dcontrails.jpg

[witchdoctor]

If you consider that any carbon based fuel produces water and carbon dioxide as a by product of combustion, then even your car would produce contrails if you got it high enough. So piston or turboprop, it doesn't matter.:8

[aviate1138]

witchdoctor says....
"If you consider that any carbon based fuel produces water and carbon dioxide as a by product of combustion, then even your car would produce contrails if you got it high enough. So piston or turboprop, it doesn't matter."

Aviate 1138 says from a cold Britain.....

On a cold morning when you start your car [presuming it is not a smoky oil burner] what do you see coming out of your exhaust? Yes! A low level contrail! As for the piston engine question there are plenty of photos of high flying piston engined aircraft making rude signs [ penis and testicles] over London during WW2.
I gather one or two USAAF Mustangs did the same thing over Berlin.


Aviate 1138

[compressor stall]

It does not matter whether the engine is jet or turbine or piston.

It's the mix of chemicals sprayed out behind the engine by us pilots on behalf of government agents for mass population mind control, weather control or (insert inferiority complex here).


chemtrails 'r' us.

[rotornut]

Right on, compressor. It's all a plot. See:

http://www.clydelewis.com/invest/contrails/

I had a headache yesterday and I saw an awful lot of contrails. I'm sure it wasn't just coincidence.:confused:

[jerrytug]

I believe they can come from tip vortices as well? Isn`t this effect due to localised rarefaction (sp?) causing water to condense and freeze? Please correct me unless I`m right,regards.

[HotDog]

Wingtip vortices are formed due to the high pressure air under the wings spilling around the wing tips into the low pressure air above the wing. These trailing vortices, spinning in opposite directions can only be seen in conditions of high humidity or cloud when the actual lift envelope is also visible above the wings. You would see the same effect if flying through smoke.

[cowabunga438]

You can often see contrails of wingtips or even flaps in the right conditions. Contrary to what has been said above you don't need freezing conditions just a relative humidity of 100%.

So either you pump a bit more water and some nucleation points into the local atmosphere raising the RH above 100% - instant contrail. - or - You you change the pressure quickly enough (adiabatically) say at a wingtip or over a flap and you can sometimes raise a parcel of air that was just under 100% RH to just over 100% RH

If you land in low cloud or near fog conditions as a pax have a look at the air over the flaps, not unusually to see wisps of cloud forming.

[White Knight]

Flying ATR's a few years back I could look down at the aircraft's shadow on the cloud below and see great long contrails behind from time to time.

[Cyclic Hotline]

Way up high at 21,000 feet.
http://users.pandora.be/willy.boeykens1/m8917.jpg

Or way down low as well.
http://www.heliopsmag.com/ImageFolio31_files/gallery/Kamov/KA-32/tn_web609.jpg

[Milt]

For the formation of contrails you need some special conditions in the atmosphere.

1 Temps below zero celcius.

2. A layer of super saturated (by water vapour) air.

3. Condensation nuleii, that is tiny particles, on which rain droplets or ice crystals form.

4. A jet or piston engine burning fuel to produce the small particles.

Con trails are a b#### nuisance if you are a fighter pilot not wanting the bad guys to see you so in such circumstances the met people can forecast the conning layer to allow the fighter jock to use to advantage.

The other stuff formed in very moist air when the air pressure and hence temperature is dropped around a fast moving or high g pulling aircraft is a mini cloud. Most of us call it 'ectoplasm"

Once again it is a nuisance if it forms around the canopy.

Condensation nucleii used in cloud seeding to produce rain is usually produced by the burning of a Silver Iodide solution.

Active seeding from ground burners is about to commence in the Australian Alps to increase precipitation.

[cowabunga438]

just a couple of probs with that post

I don't think you need either temp below zero, or super saturated air.

Certainly supersaturated air will help, but you can get contrails at an ambient RH of less than 100% because you put more water into the air (and thus can rise the local RH to above 100%).

If the air is supersaturated you do not need to add any water - just add condensation nuclei.

Non supersatured air will also form contrails behind wingtips/flaps etc because the wing changes local RH.

The temp is also irrelevant. You can get contrails at above 0 degrees. Relative humidity is the important thing.

You can get condensation about the wing tips of aircraft near the ground on hot balmy days in poor weather (RH basically almost 100%). You are less likely to get contrails behind an engine in these conditions because the exhaust is hot (so lowers local RH). At altitude the exhaust quickly cools.

[OnTheStep]

localized reductions in pressure are enough to bring the surrounding air to the saturation point, et voila!

vapor coming off the prop tips in our 208 during the summer is not uncommon