EddieWeeks

Well I don't know.. The problem I am having is the pressure drop required for just one deg F of
temp change will rip the wings off... One thing in the water vapor favor is the Firebird does not
have any washout and it uses a cambered airfoil on the wing tip.. Both of these will
create lower pressure.. This type of wing design is quite uncommon and that would explain
why its the only plane doing it..

I too have seen the Indy cars at >160 mph make nice vapor trails but there wing is at like 30 deg
AOA... The fire bird needs only ~ 1 deg AOA to pull 5 Gs at 200mph....

I guess it possible with the cambered wing tip to create a high speed small vortex..

A good test would be to fly at the same height as cloud layer, this is where the dew point and temp are the closest..

Sean, although I enjoyed your lecture on Thermodynamics, I found your description of the event to
be far more useful...

I like the drag car... My turbine car is at the machine shop waiting for the CNC mill to free up..
will keep you posted..

Eddie Weeks

patf

My Feedback: (4)

eddie can i tell you about clouds now? the fluffy ones that look like puppies?

AnthonyW

And this one time. At band Camp.............

erbroens

That´s all it takes to make a huge pressure differential in the wings! so not a big AOA is needed..
anyway, I think that everybody is thinking now in modifiying wingtips and wing planforms to maximize this effect that should look cool! the only problem is choosing a cold and rainy day
to make it happen.

Enrique

seanreit

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Lecture wasn't for you, clearly you know more about this than I do, it was for all the naysayers that said it was fuel vapor. Once they get a good picture as to what's really happening they'll be more apt to understand how and why it happens. I didn't know anything special about the Wings on that airplane other than they look cool and have what appears to be a sharp tip. All I really know is that I can just about explain how it could happen and tell anyone that I saw it happen at least twice and maybe three times three years ago.

I mean really.......... I had to ask you last year where Isobar came from What's an ISO

seanreit

My Feedback: (60)

By the way, if this is true, I would have to say that what I saw was either impossible, or that the dewpoint and temperature were signifcantly less than 1 degree apart (which I don't think was true). I'm trying hard to remember the weather conditions. One thing that is puzzling me is that the flight was around 11 am (by that time I would think the T and dew point would be further apart) and while I don't remember a huge clear sky, it was pretty cloudy (so maybe not). This was the year that the hurricane hit down in your area. In fact the eye of that hurricane went over the runway at Superman late that afternoon. I remember that part for sure as several people mentioned how crazy the weather just opened up into the clearest day imaginable and then went back to the dreaded overcast that had been there all day. Anyway, wish I knew more about how the pressure changes can be done with the airfoil, It's everything I can do just to get the concepts most of the time. I have no practical use or understanding of just about anything.

S_Ellzey

Hi Eddie,

Actually the wing tip vortex does not tend to create lift, at least not much. I have seen condensation trails coming off the wing tips of wind tunnel models at about the same condition we fly at if the humidity is right. One delta wing model I tested once spun up a massive vortex (which did create a lot of lift, and drag) and at times the core was visible around 6 feet behind the model. Of course the only reason you could see the condensation was the model was sitting still and we could get to within 6 feet of it, and adjust the lighting. My guess would be that the shape of the Firebird tip and wing planform is causing it to spin up a stronger than normal vortex, which is bad, that creates drag.

Steven

EddieWeeks

Sounds like its possible then... I was thinking only of the pressure drop over the top of
wing to fly the plane.... I forgot about a small vortex haveing a much lower pressure...
oh.. well .. learn somthing new everyday...

Eddie Weeks

Tom Antlfinger

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Might that not be the reason for Tom adding winglets.....not only reduces tip vortices, but also provides additional yaw stability ala Zagi, along with his new vertical fin/rudder design......wonder if you can get the winglet version Firebird to blow steam off the tips....

The performance increases produced by those little winglets on the big birds like the Lear 45, 737, 747, and big G's is quite remarkable........a while back, someone had a video in a booth at EAA, not sure if it was NASA, with wind tunnel shots with and without the winglets......dramatic decrease in wing tip vortices.....almost disappear, along with the drag at high Mach speeds......

Tom