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WWMaxGunz
11-22-2006, 07:57 PM
But as more wing becomes stalled we do not make cloud/smoke over that whole part, only tip.

1) it would be neat to have a visual indicator of how much and where wing is stalled.
2) there must be some reason we don't see that like because it doesn't do that but then
are there always tip-stall plumes?

Maybe it's the vortex?

The-Pizza-Man
11-23-2006, 02:05 AM
I think it's number 2.<div class="ev_tpc_signature">

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Arm_slinger
11-23-2006, 07:52 AM
Its because the high and low pressures converge at the wing tip and generate a vortex, this I beleieve compresses moisture in the air, and thus gives a visual indication.

I think thats the generalised explanation, I don't have my university notes on me to explain further.<div class="ev_tpc_signature">


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NonWonderDog
11-23-2006, 10:36 AM
Yep, it's not a wingtip stall, it's just a strong wingtip vortex that creates the contrail. The wingtips always stall after the inboard section of the wing, remember.

The clouds you often see sheeting off the wings of F-15s and 747s don't have anything to do with stall, either. That's just to do with very effective wings, creating a low enough pressure that the moisture in the air precipitates out. The strange patterns you see on fighter aircraft are due to the delta wings; at high angles of attack they generate lift with lines of strong vorticies attached to the upper surface of the wing instead of just a low-pressure region. You probably wouldn't see clouds sheeting off the wings of WWII aircraft unless it was a somewhat cold day at 100% humidity.

LEXX_Luthor
11-23-2006, 03:45 PM
Dog::
You probably wouldn't see clouds sheeting off the wings of WWII aircraft unless it was a somewhat cold day at 100% humidity.
It became USAAF unofficial training policy for instructors on the ground to call out to trainee pilots during landing to tighten their turn to final approach if the instructors failed to see wing-tip contrails. In the dry desert, this only led to trainee pilots stalling low to the ground and getting killed, as wingtip contrails would not form even at the stall and beyond.


MaxGunz::
1) it would be neat to have a visual indicator of how much and where wing is stalled.
2) there must be some reason we don't see that like because it doesn't do that but then
are there always tip-stall plumes?
(1) It would be "neat" but I don't think real life pilots could safely judge turning and approach to stall by wingtip condensation trails for the reason poasted above -- different air conditions. Now, you might "judge" the contrail by looking at it, but you won't be judging any stall or turning condition as the killed Newbie pilots and their ignorant instructors found out.

(2) No, not always a contrail, and if there was one, I would guess the amount of contrail would depend on atmospheric conditions, and that's what you would be judging -- contrail.<div class="ev_tpc_signature">

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JamesBlonde888
11-23-2006, 11:33 PM
Originally posted by WWMaxGunz:
But as more wing becomes stalled we do not make cloud/smoke over that whole part, only tip.

1) it would be neat to have a visual indicator of how much and where wing is stalled.
2) there must be some reason we don't see that like because it doesn't do that but then
are there always tip-stall plumes?

Maybe it's the vortex?

This is because the wings stall before the horizontal stabilisers due to their longer span, camber and position on most aircraft. The turbulence created by the stalling wing also disrupts the airflow over rear stabilisers and prevents vapour from forming visibly.<div class="ev_tpc_signature">

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WWMaxGunz
11-24-2006, 12:10 AM
Totally dig and agree with you guys.

One little question/observation....



Originally posted by NonWonderDog:
That's just to do with very effective wings, creating a low enough pressure that the moisture in the air precipitates out.

Lower pressure than on the surface of a flow-separated wing?

Well, I guess if you go fast enough. Props at high alt would contrail the whole length and
one bomber pilot I knew said they would sometimes be able to get the contrails to stop just
by adjusting the rpm's a bit, trade efficiency for not leaving a trail across the sky.

LEXX_Luthor
11-24-2006, 05:09 PM
Gunz::
Props at high alt would contrail the whole length and
one bomber pilot I knew said they would sometimes be able to get the contrails to stop just
by adjusting the rpm's a bit, trade efficiency for not leaving a trail across the sky.
Interesting. Or the pilot was depending on contrails starting from the exhaust content, which changes with rpm's. Generally the long streams of contrails behind aircraft that I think you are referring to here form by the exhaust particles starting a condensation chain reaction, or so my understanding goes.<div class="ev_tpc_signature">

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JamesBlonde888
11-24-2006, 05:11 PM
It would need to be very moist air too. Moist and cold air at altitude can make vapour at the drop of a hat... literally.<div class="ev_tpc_signature">

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WWMaxGunz
11-27-2006, 12:40 AM
No Lexx, Joe was very clear about those coming from the props.

LEXX_Luthor
11-28-2006, 07:08 PM
Understood!<div class="ev_tpc_signature">

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actionhank1786
11-29-2006, 10:13 PM
I've always loved the pictures of navy planes in the pacific getting ready to take off, with the spiral pattern contrail coming off the wing tips.
Just a certain beauty to it!<div class="ev_tpc_signature">

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Nimits
12-01-2006, 04:57 PM
My favorites in that category are the F6Fs with the "prop halo;" that really does look cool.