Flying Roof Panels

[Noodles 4.2]

Ah, the quirks of TVR ownership. Never a dull moment!

Flying panels, eh? I find it scary enough in the Cerb at 140ish when the door windows get sucked outwards creating a hell of a noise. Scares me everytime.

Why not get one of things that surfers connect their boards to their ankles with and attach one end to the panel?

Tony

[Ballistic Banana]

Noodles 4.2 said:

Why not get one of things that surfers connect their boards to their ankles with and attach one end to the panel? Tony

Have you been on the sauce again Tony, or up in the Loft/attic

BB

Edited to add, prehaps if this cord was attached to the Handbrake when it comes off it would slowely apply the Handbrake

>> Edited by Ballistic Banana (moderator) on Saturday 5th July 18:42

[Noodles 4.2]

Who told you about my attic?

[simpo one]

Now you know why I told you about the bag with loops to put your feet in....

[bassfiend]

/me has visions of the scene in "Lost Boys" where the Max Power neanderthal and his bint are extracted vertically from their car after the soft top is ripped off!

Phil

[pete]

maca said:

The lifting force on an aircraft wing is not created because the upper wing surface is longer and more curved than the lower.

Oh yes it is! Lift is created due to vorticity, which is a direct consequence of air flowing in a curved path. More curvature, more vorticity, air flows faster (there's the Bernoulli bit), ergo lift. Of course if the surface is too curved you suffer from separation and complete loss of lift, but I'm sure you know that

I could derive it from first principles using the law of conservation of momentum, but I've got work tomorrow!

Pete

p.s. Before anyone points out that an inclined flat surface generates lift almost as well as a curved one, so it can't be due to curvature, just take a look at the 2D streamlines of airflow around the surface...

[maca]

name said:

Oh yes it is! Lift is created due to vorticity, which is a direct consequence of air flowing in a curved path. More curvature, more vorticity...

exactly. the point was that this is not due to the upper surface being more curved and 'longer' than the lower surface. That they can create lift simply from path length difference which leads to pressure difference is the concept that's both misleading and flawed.

The Bernoulli effect rather explains how the top of the wing is able to "pull downwards" on the air flowing over it. The contribution to the total lift from the negative pressure developed at the upper surface is larger than the contribution from the positive pressure at the lower surface.

Explanations due to circulation, flow-turning or curvature-of-streamlines, and vortices are indeed what we use to describe this phenomenon more accurately. But they all depend on Newton's 3rd, the Coanda effect, and Conservation of Momentum not purely the misuse of the Bernoulli effect.

[pete]

Sorry maca, I just couldn't resist. My pet hate is the "air has to catch up so goes faster" explanation - I was once even pulled up on this lame simplification by a 14 year old in a "aero engineering is fun" workshop!

Still, empirical evidence suggests that keeping your roof struts tight and well adjusted will help you avoid a 500 quid bill...

Cheerio,
Pete
(embittered ex-aerodynamicist )

[simpo one]

By vorticity I guess you mean turbulence? This actually destoys lift, which is why planes stall and fall out of the sky if the angle of incidence gets too great.

[RichB]

pete said:

maca said: The lifting force on an aircraft wing is not created because the upper wing surface is longer and more curved than the lower. Oh yes it is! Lift is created due to vorticity... etc... p.s. Before anyone points out that an inclined flat surface generates lift almost as well as a curved one, so it can't be due to curvature, just take a look at the 2D streamlines of airflow around the surface...

Just like to pint out that a friend of mine is a competitive aerobatics pilot flying giders (no engine) and the cross section of the wings on his aerobatic glider are the same top to bottom. This of course allows him to fly upside down, and as the glider flys makes a nonsense of the theory that lift is only produced because of the eyebrow cross section of the top surface of the wing. It is, of course, mainly due to angle of incidence and secondarily due to the wing cross section etc. etc. Rich...

[siwes]

I know whats happening , the car is trying to take off a well known problem with these cars at these speeds a few more mph and the car would more than likely follow the roof , I think TVR must have employed a designer from wharton when building these things.
regards
Simon

[shpub]

No but I am pretty sure that Audi and Porsche did judging by the bits of plastic that they had to hurredly fit to stop the TT and Boxter taking off at normal road speeds...