Helicopter Ice cloud - video....pictures?

[ralphmalph]

Hello,
I am producing some ground-school notes and have tried to find still pictures of an aircraft logging in N America which produces its own ice cloud as it comes to the hover. Its a great video, saw it a long time ago.....cannot find it again anywhere. Tried googling many different titles to no avail. Could anyone point me in the right direction for a still?

Would be very much appreciated, deployed at the moment and dont have that much time/bandwidth to search for any length of time.

Regards and thanks in advance.

Ralph

[No-ID]

Still had it in my favourites:

205FuelHaul2004-40C.mp4 video by flyboygms - Photobucket (http://s97.photobucket.com/albums/l240/flyboygms/?action=view&current=205FuelHaul2004-40C.mp4)

Good luck!

[helisdw]

ralphmalph,

I don't know if this is what you had in mind (it's a video rather than still photographs):

205FuelHaul2004-40C.mp4 video by flyboygms - Photobucket (http://s97.photobucket.com/albums/l240/flyboygms/?action=view&current=205FuelHaul2004-40C.mp4)

It was originally posted by rotorfloat in 2006 in the Rotorheads video section.

If you've got a photobucket account you can copy the video but I don't think it can be directly downloaded from the internet (although I'm sure someone with greater IT skills will be able to suggest a way!).

Simon

[Hell Man]

Ralph - you're lucky to get so many quick responses! Hope you soon get a full time broadband connection! Here in the US they're inexpensive.

Had something similar happen with a 214B in North Dakota once. My crewman got kinda excited.

There were also some pretty tip vortices we produced with the Slick in Nam in the early mornings and high humidity.

HM

[Noah Zark.]

Just an observation from not an expert, but it is noticeable how the ice cloud muffles the noise the helo is making as it climbs away.

[obnoxio f*ckwit]

Not ice, but landed one night by the river in a shallow valley in Poland on a cool, clear & still night, just as the wheels touched everything went white (well green actually) as we made our own fog cloud. On lifting you could see how localised it was, no more than about 50 metres all round. Quite spooky at the time, a few seconds earlier it could have got interesting.

[ralphmalph]

Thank you very much guys....just what I wad after!

regards

Ralph

[pasptoo]

Interesting phenomena, anyone got details on how this actually forms?

As the cloud forms it then seems to follow the aircraft, it can't be as straight forward as first thought. Is it a factor of the particulate from the exhaust? or does the air temp have to be extremely low to produce. Is there any adverse affect on the airframe?

I have have worked in a variety of regions in temps of -30 to +40 degC and not come across this before.

Thanks
P.

[elro]

Flying IMC in VFR :}

[rotorrookie]

D9x3Beciw1s (http://www.youtube.com/watch?v=D9x3Beciw1s&feature=related)

[Phoinix]

I would also like to know more about the phenomena, if anyone would like to share some information :confused:

[lelebebbel]

I would assume that this is an effect similar to the formation of mountain cap clouds or wingtip-vortex-trails on fighter jets?

Air is being accelerated by the airfoils -> increased velocity leads to reduced pressure -> this leads to reduced temperature -> humidity condensates or deposits into fog or ice crystals, forming the cloud.

[Phoinix]

Seems logic, I understand but is this water vapor or ice particles? How do low temperature contribute? One condition for this phenomena is high relative humidity in which we fly often, but I have never seen it.

I'm more interested in the meteorological conditions behind it.

[Landroger]

No expert at all, but it seems to be related to blade loading. The 212 didn't display the phenomenon until it lifted the load and then it did it in spades. The helo at the ski resort suddenly did it on the approach - from both the main and tail rotor. On the ground it was still burning and turning, but no cloud apparent.

I always understood that in the very, very cold conditions as in the 212 clip, the humidity is, by definition, very, very low - otherwise it would snow, wouldn't it? So, exactly how and from what, are those rotors beating ice out of thin air? :confused:

Roger.

[Winnie]

The moisture that comes from burning fuel? byproducts in other words?

Cheers
H.

[ShyTorque]

I've seen the phenomenon quite a few times from the cockpit to some degree or another. I don't think it is directly temperature related because I've had it occur in UK (temperate), in Central America (tropical) and in winter in southern Germany (damned cold). I think what is more important is the relative humidity of the local air.

I'm fairly certain that the "stirring" action of the rotor blades is the trigger for the air to suddenly reach 100% humidity and for visible water to precipitate out of the air.

Exactly the same thing happens when a fast jet pulls hard and visible vortices appear off the wing tips. These are often seen during flying displays, I remember this very vividly from my childhood visits to Farnborough Air Show in particular.

Presumably the vortex (wing or rotor blade) produces a local low pressure and temperature which causes the air within and around to become saturated. Or perhaps the local air was already supersaturated and needed a trigger action for water particles to precipitate, which the aircraft provides. This would explain the spreading of the visible trail behind or below the aircraft in some cases.

[lelebebbel]

exactly

http://i716.photobucket.com/albums/ww164/uncletogie/F-22_Raptor_vapor_trails.jpg

In warm conditions, the cloud disappears because the humidity is quickly absorbed by the surrounding air.
In case of an ice cloud (deposition), the ice crystals will apparently hang around longer and fall to the ground


No expert at all, but it seems to be related to blade loading.
More blade loading -> greater pressure changes -> more vapor. Same with the clouds on the fighter jets, they only appear during high-G manoeuvres.
in the very, very cold conditions as in the 212 clip, the humidity is, by definition, very, very low - otherwise it would snow, wouldn't it?
The absolute amount of water might be low, but relative humidity can still be very high.

[Coconutty]

lele - Great pic :ok: ....

"Switching to Stealth mode !" ;)

http://i34.photobucket.com/albums/d129/coconut11/Coconutty.jpg