Air turbulences@ >130mph "opening" the doors
Discussion
23:29, just arrived from a long trip visiting the builder of the 3rd german ultima. Drove a lot on autobahn, >130mph, up to 160mph...Recognized, that at speeds over approx. 130mph, the air seems to cause turbulences right over the doors, which lead to a lifting of the doors, although they´re are fully engaged....at higher speeds it´s that much, that you can nearly put a finger through it....The gap accrues on the very top (so to say the roof part of the doors)..Anyone experienced this already ? Did anyone made any stiffening or additional locks or smth. to solve that ? Would be thankful for any comments...
Edited by lvjost on Wednesday 4th October 22:35
so GUY you think the air gets pushed into the cabinet and tries to get out and
crafty, you think of turbulences above the roof as cause for this phenomenon ?
Guy: What did you do ? Did you change something or did you decide to never go high speed again ?
Crafty: Are you just speculating with us or did you experience something like that on your GTR as well ?
crafty, you think of turbulences above the roof as cause for this phenomenon ?
Guy: What did you do ? Did you change something or did you decide to never go high speed again ?
Crafty: Are you just speculating with us or did you experience something like that on your GTR as well ?
Speculating, (mine hasnt moved faster than walking pace yet) but the roof is a low pressure zone. I was gonna say look at the video also.
Maybe its a combination of both effects? The easy way to find out is to block all of the areas that air can come in at the front of the cabin.
Hang on.... come to think of it... with the gaps under the doors I would expect that any air coming through the front would make its way out there... Im sticking with the low pressure sucking the roof up.
You'll need additional catches on the roof if you want to stop that.
Maybe its a combination of both effects? The easy way to find out is to block all of the areas that air can come in at the front of the cabin.
Hang on.... come to think of it... with the gaps under the doors I would expect that any air coming through the front would make its way out there... Im sticking with the low pressure sucking the roof up.
You'll need additional catches on the roof if you want to stop that.
I haven`t experienced this effect so far (up to 170mph). The only thing that I realise is that the helicopter vents sound like their name suggests - like a helicopter turbine on each side of your head...
You mentioned before that you have some "excess" trim on the doors, i.e. the areas where the seals are supposed to do their job are covered in leather - maybe this adds to the effect as well as air pressurizing the cabin. That`s impressive if you know how much a private aircraft with a pressurized cabin would cost.
You mentioned before that you have some "excess" trim on the doors, i.e. the areas where the seals are supposed to do their job are covered in leather - maybe this adds to the effect as well as air pressurizing the cabin. That`s impressive if you know how much a private aircraft with a pressurized cabin would cost.
I've had a TVR V8S once and noticed that when I drove faster then 180km/h orso that the targatop and the rearsoftwindow piece moves they tried to seperate
and over 220km/h it pops out on one site lucky on the front there where 2 clips so it did not go skyhigh but I slowed down
scary...I hate it since I knew that...
I thought it came from pressure build up inside...but it could also be lift? but then I don't understand why it moved outwards..I think its both...like when you drive some VW golf cabrio(never had one though) and you see them on the autobahn..you see the softtop almost blow up(older models) so then its pressure from inside more air in then can go out? and the doors of an Ultima GTR are a bit flexible so it goes up in the corner a bit?
GTRene
and over 220km/h it pops out on one site lucky on the front there where 2 clips so it did not go skyhigh but I slowed down scary...I hate it since I knew that... I thought it came from pressure build up inside...but it could also be lift? but then I don't understand why it moved outwards..I think its both...like when you drive some VW golf cabrio(never had one though) and you see them on the autobahn..you see the softtop almost blow up(older models) so then its pressure from inside more air in then can go out? and the doors of an Ultima GTR are a bit flexible so it goes up in the corner a bit?
GTRene
Edited by GTRene on Thursday 5th October 11:14
I did not notice such issues at 170mph+ either but then again I am not sure I would have seen it, helment on and all.
Casting my mind back a bit I did see the door on the blue British GT car fly off at high speed a couple of years back. Although the car was heavily modified I don't know if the doors were standard but the effect was probably the same, low pressure outside (ie fast airflow) and high inside (relatively).
Casting my mind back a bit I did see the door on the blue British GT car fly off at high speed a couple of years back. Although the car was heavily modified I don't know if the doors were standard but the effect was probably the same, low pressure outside (ie fast airflow) and high inside (relatively).
lvjost said:
23:29, just arrived from a long trip visiting the builder of the 3rd german ultima. Drove a lot on autobahn, >130mph, up to 160mph...Recognized, that at speeds over approx. 130mph, the air seems to cause turbulences right over the doors, which lead to a lifting of the doors, although they´re are fully engaged....at higher speeds it´s that much, that you can nearly put a finger through it....The gap accrues on the very top (so to say the roof part of the doors)..Anyone experienced this already ? Did anyone made any stiffening or additional locks or smth. to solve that ? Would be thankful for any comments...
Edited by lvjost on Wednesday 4th October 22:35
Lutz. This is the way I did it but bear in mind that you cannot open the doors from the outside when the safety catches are engaged. Alan.
[pic][URL=http://imageshack.us]
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Alan 2 said:
Lutz. This is the way I did it but bear in mind that you cannot open the doors from the outside when the safety catches are engaged. Alan.
[pic][URL=http://imageshack.us][/URL][/pic]
[pic][URL=http://imageshack.us]
[/URL][/pic]So I guess that's a post SVA mod then?
Crafty is right...the air moving over the car creates a negative pressure zone compared to the cabin, this air being almost still. Additionally air being forced into the cabin through gaps around the steering column and also through any ducting etc. (e.g. helicopter vents) will increase the pressure in the cabin. As you know, the air wants to get from the high pressure zone to the low pressure zone, i.e how a wing creates lift on an aircraft. If you then have an ill fitting door seal the problem only gets worse as the air has found a route out and will expoloit the weakness.
You have raised and interesting question though and I do not know if my GTR does the same. I will have to complete a test run ASAP and let you know. I have not noticed the effects of the doors lifting but then I am concenttrating 100% on the road at these speeds.
S
You have raised and interesting question though and I do not know if my GTR does the same. I will have to complete a test run ASAP and let you know. I have not noticed the effects of the doors lifting but then I am concenttrating 100% on the road at these speeds.
S
Hi Guys. Thanks to all of you for your comments and ideas. First I want to make a statement:
No, I neither didn´t nor don´t look up at speeds like 170mph...to see the doors are lifting.
Of course not. I may be german and allowed to go 170mph legally on streets, but I´m neither
weary of life nor stupid !
I actually felt the problem, as cold air was suddenly blowing around
my head when increasing speed which didn´t occur before and on speeds below 120 mph...
To Alan 2: Looks like a very effective solution for the problem. Where did you buy the lock mechanism..? Is
it a car-related part or something from the "furniture"-market.. ?
To bluesatin: Don´t want to offend you, but IMO there´s a big difference between your "runs" and my "trips"..
The duration...30 seconds or even a minute at these speeds may not cause that much demand for the material. But in nightly germany after 22:00 there are roads you can go >170mph for 10-15 minutes non-stop...And if there would be a problem with the door lock or the door leaver etc. it is much probable, that you´ll find your door(s) somewhere in the landscape then...I think there is a big difference between short- and long-term loading of material...
To scuff: Thanks. Please do let me know, if the problem occurs with/by/to (?) you...
No, I neither didn´t nor don´t look up at speeds like 170mph...to see the doors are lifting.
Of course not. I may be german and allowed to go 170mph legally on streets, but I´m neither
weary of life nor stupid !
I actually felt the problem, as cold air was suddenly blowing around my head when increasing speed which didn´t occur before and on speeds below 120 mph...
To Alan 2: Looks like a very effective solution for the problem. Where did you buy the lock mechanism..? Is
it a car-related part or something from the "furniture"-market.. ?
To bluesatin: Don´t want to offend you, but IMO there´s a big difference between your "runs" and my "trips"..
The duration...30 seconds or even a minute at these speeds may not cause that much demand for the material. But in nightly germany after 22:00 there are roads you can go >170mph for 10-15 minutes non-stop...And if there would be a problem with the door lock or the door leaver etc. it is much probable, that you´ll find your door(s) somewhere in the landscape then...I think there is a big difference between short- and long-term loading of material...
To scuff: Thanks. Please do let me know, if the problem occurs with/by/to (?) you...
Edited by lvjost on Friday 6th October 09:57
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