Discussion
Hmmmm I wonder what speed it would have to go
If you add up all the forces acting against the road (600kg car, 1000kg of downforce, and centripedal forces), then multiply that by the coefficient of friction of the tyres say 1.2, then you have 1600*1.2 = 1920kg's of latteral force. Since the car weighs 600kg's, 1920/600 = 3.2 g's of latteral acceleration.
If you're driving upside down, then the downforce will be up, but the weight of the car will be down, so you have 1000 - 600 = 400 kg's, times 1.2 (grip of the tyres) = 480 kgs, 480/600 = 0.8g's of latteral acceleration.
Latteral acceleration is a combination of acceleration or breaking, and sideways acceleration. If you need 100 kg's of forward force to maintain whatever speed you want upside down, then you need 100 / 1.2 (tyres) = 87kg's of force against the ceiling(after you take into account the weight of the car), so you'll need at least the weight of the car, + 87 kg's = 687 kg's of 'downforce' from the wings (acting upwards if you're upside-down).
So not really that realistic a proposition really
Possible to maintain it for a short time though
If you add up all the forces acting against the road (600kg car, 1000kg of downforce, and centripedal forces), then multiply that by the coefficient of friction of the tyres say 1.2, then you have 1600*1.2 = 1920kg's of latteral force. Since the car weighs 600kg's, 1920/600 = 3.2 g's of latteral acceleration.
If you're driving upside down, then the downforce will be up, but the weight of the car will be down, so you have 1000 - 600 = 400 kg's, times 1.2 (grip of the tyres) = 480 kgs, 480/600 = 0.8g's of latteral acceleration.
Latteral acceleration is a combination of acceleration or breaking, and sideways acceleration. If you need 100 kg's of forward force to maintain whatever speed you want upside down, then you need 100 / 1.2 (tyres) = 87kg's of force against the ceiling(after you take into account the weight of the car), so you'll need at least the weight of the car, + 87 kg's = 687 kg's of 'downforce' from the wings (acting upwards if you're upside-down).
So not really that realistic a proposition really
Possible to maintain it for a short time though
Think they produce their own weight in downforce at about 90mph. It doesn't matter that the downforce would be pushing upwards and the weight of the car downwards. As long as the downforce was greater than the weight of the car it would stick, surely? Because the force pushing upwards would be greater than the force pushing downwards. I think to be totally safe and to have any chance of having enough weight and load going through the suspension and tyres to have control of the car you'd have to be doing at least 140-150, and to make it feel anything like it would the right way up, I'd say you'd have to be the far side of 200mph. Bear in mind that if the car weighs 600kg, and it was producing 700kg of downforce at 100mph, driving it upside down would put a load of just 100kg through the tyres, which would make it pretty much uncontrollable I'd imagine. You'd need at least 1400kg of downforce to make the car driveable.
Sorry if thats what your post was saying Condor, not to good with numbers me
Sorry if thats what your post was saying Condor, not to good with numbers me
condor said:
Think you need an extra g to counteract gravity
Gravity cancels out in the equations that we're talking about. We're just using the wrong terms, as we're referring to the down"force" as a measure of mass (kg). But that's okay as long as we're consistent.
If the car "weighs" 600kg and the wings produce the equivalent of 600kg of "downward" "weight". Then running on a ceiling, you would have a "weightless" car because the "down"force (now acting up) would equal exactly the car's "weight" still acting down. Confused yet?
So, DJ 27 is right, to make the car seem right, you would need to create double the cars weight in downforce. Whether the figure of how much they produce is 2.5 times or 5 times (highly dependent on setup I suspect) then twice the car's "weight" is eminently possible. So, you could do it, fluids allowing.
It's a long time since I did engineering....so might be a bit rusty...especially as that was with aircraft.
I was thinking more on these lines.
When the car has no downforce it has 1g (*600kg) of downward force or otherwise 600kg of normal force pointng downwards. If you have 2g's downforce, then the normal force on the wheels is 3g's or 1800kg total. When you flip the car over, you have to subtract 1g just to keep the car neutral. Then you have to subtract another g to simulate the weight of the car on the ground with no downforce. Now you have 1g of downforce left.
I was thinking more on these lines.
When the car has no downforce it has 1g (*600kg) of downward force or otherwise 600kg of normal force pointng downwards. If you have 2g's downforce, then the normal force on the wheels is 3g's or 1800kg total. When you flip the car over, you have to subtract 1g just to keep the car neutral. Then you have to subtract another g to simulate the weight of the car on the ground with no downforce. Now you have 1g of downforce left.
condor said:
It's a long time since I did engineering....so might be a bit rusty...especially as that was with aircraft.
I was thinking more on these lines.
When the car has no downforce it has 1g (*600kg) of downward force or otherwise 600kg of normal force pointng downwards. If you have 2g's downforce, then the normal force on the wheels is 3g's or 1800kg total. When you flip the car over, you have to subtract 1g just to keep the car neutral. Then you have to subtract another g to simulate the weight of the car on the ground with no downforce. Now you have 1g of downforce left.
I see what you're saying and, you are correct but we are only concerned with whether the car can be driven upside down. We're not going to expect equivalent lap times so we don't have to worry about exerting "down"force on the ceiling other than to keep the car up there. So, assuming that a wingless F1 car is driveable then we only have to create enough "down"force to cancel out the weight and then create a pseudo-weight. So, double the cars own weight to make it driveable.
A fair point. Okay then, we can work this out, though we'll have to use some pretty major assumptions.
First, we'll exclude drag as this just reduces top speed and doesn't reduce the wing effectiveness. We will assume that we have an engine powerful enough for whatever speed we come up with.
F = 0.5*span*cord*angle*coeff*ro*v^2
We will take very approximate values of span as 1.2m, cord as 0.2m, angle of attach as 10 degrees = 0.173 radians. ro = 1.225
Next assumption, we'll believe the oft quoted value of 160km/h (44.44 m/s) at which an F1 car can create its own weight (600kg = 5880N of downforce) of downforce.
We're now going to make the next huge assumption which is the most dodgy of all. Remember them diffusers? Well ours just fell off!
We are considering wings only (the figures we've used make bigger than actual wings so that compensates for the lack of a diffuser to some extent), there are 2 wings, we'll assume force is equal from both. So, divide our force between the 2.
So plug in the figures to get a coeff.: 2*2940/(1.2*0.2*0.173*1.225*44.44^2) = 58.54
We need an extra 5880N of force to be our car's weight. Rearrange again and plug in the higher force and our coeff to get: 2*5880/(1.2*0.2*0.173*1.225*58.54) = 3929.5
This is v^2, so v = 62.68m/s = 225.6km/h.
So, around the 140mph mark. Good luck and let me know if you manage it.
First, we'll exclude drag as this just reduces top speed and doesn't reduce the wing effectiveness. We will assume that we have an engine powerful enough for whatever speed we come up with.
F = 0.5*span*cord*angle*coeff*ro*v^2
We will take very approximate values of span as 1.2m, cord as 0.2m, angle of attach as 10 degrees = 0.173 radians. ro = 1.225
Next assumption, we'll believe the oft quoted value of 160km/h (44.44 m/s) at which an F1 car can create its own weight (600kg = 5880N of downforce) of downforce.
We're now going to make the next huge assumption which is the most dodgy of all. Remember them diffusers? Well ours just fell off!
We are considering wings only (the figures we've used make bigger than actual wings so that compensates for the lack of a diffuser to some extent), there are 2 wings, we'll assume force is equal from both. So, divide our force between the 2. So plug in the figures to get a coeff.: 2*2940/(1.2*0.2*0.173*1.225*44.44^2) = 58.54
We need an extra 5880N of force to be our car's weight. Rearrange again and plug in the higher force and our coeff to get: 2*5880/(1.2*0.2*0.173*1.225*58.54) = 3929.5
This is v^2, so v = 62.68m/s = 225.6km/h.
So, around the 140mph mark. Good luck and let me know if you manage it.
well done gavyn for the maths ....you came up with the same sort of speed that the DJ 27 came up with
I'd have to say....it still seems a bit slow to me.....though theoretical calculations re practise are often a bit out
I'd like to add in another coefficient ( for all the bits we knocked out) and suggest a speed of 180 mph would be feasible.
Agreed ?....lets get someone to try it
....you came up with the same sort of speed that the DJ 27 came up with I'd have to say....it still seems a bit slow to me.....though theoretical calculations re practise are often a bit out
I'd like to add in another coefficient ( for all the bits we knocked out) and suggest a speed of 180 mph would be feasible.
Agreed ?
....lets get someone to try it 
gavyn said:
More, far more. Aerodynamic theory and it's application in F1 has moved on far enough that a modern diffuser which works on the same principle as the old ground effect cars but is limited to starting from the rear axle produces around the same downforce as the full length venturis of the 80s I believe.
You then have the far more advanced wings and the fact that the bodies themselves now create downforce as well.
That said, as a principle, ground effect is still far more effective than anything in use today and, if applied with modern understanding and the benefits of active suspension to keep the cars pitch and roll neutral, the potential downforce is HUGE!
I read something from Patrick Head (I think) who said that if the technical regs had been left unchanged at the end of 1992, that the peak G loadings in corners would now be in the region of 8g, instead of 4g. Imagine modern aero theory applied to a wider car, with big fat slicks, active suspension and a flat bottom with a huge diffuser. The drivers would be wearing G suits like fighter pilots do
The DJ 27 said:
I read something from Patrick Head (I think) who said that if the technical regs had been left unchanged at the end of 1992, that the peak G loadings in corners would now be in the region of 8g, instead of 4g. Imagine modern aero theory applied to a wider car, with big fat slicks, active suspension and a flat bottom with a huge diffuser. The drivers would be wearing G suits like fighter pilots do
I think I have that article too. Will seek it out. He was basically postulating on how fast a car would go if nothing had been banned. Was envisaging a car with ground effect, active suspension, traction control (was illegal when the article was), CVT, slicks, the whole works. Was very interesting. I will try and find it if people are interested?
On a similar line - if an object is placed on the front wing of an F1 car, the moment it turns right, the object would fly off to the left. Why then, does a driver's head get pulled in to the right?
Also, I've read that any winged car creates massive drag - enough to stop it dead! So, if one could devise a way to create huge downforce yet minimal drag, you would have the perfect aero package - is that right?
Also, I've read that any winged car creates massive drag - enough to stop it dead! So, if one could devise a way to create huge downforce yet minimal drag, you would have the perfect aero package - is that right?
steviebee said:
On a similar line - if an object is placed on the front wing of an F1 car, the moment it turns right, the object would fly off to the left. Why then, does a driver's head get pulled in to the right?
Also, I've read that any winged car creates massive drag - enough to stop it dead! So, if one could devise a way to create huge downforce yet minimal drag, you would have the perfect aero package - is that right?
The driver leans his head into the corner, the same way anyone on the road does. If a driver is exhausted at the end of a race his head will get flung all over the place.
On the subject of drag, I've read that if you simply lift the throttle in an F1 car at 180mph, and don't touch the brakes, it slows down as quicky as doing a full bore emergency stop in a road car, purely beacuse of aero and tyre drag. Another interesting statistic I've read is that during heavy braking, the force gonig through the drivers neck is the equivalent of trying to lift a widescreen TV using nothing but your head and neck. Think about doing that three or four times a lap, for an hour and a half.
The DJ 27 said:
Another interesting statistic I've read is that during heavy braking, the force gonig through the drivers neck is the equivalent of trying to lift a widescreen TV using nothing but your head and neck. Think about doing that three or four times a lap, for an hour and a half.
I've thought about doing it during a grand prix to make the afternoon appear more interesting though!Gassing Station | General Motorsport | Top of Page | What's New | My Stuff