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# Ultimate Race Tracks

A little down-force can go a long way!
 (+4, -4) [vote for, against]

This particular idea will most certainly work with Formula One racing, CART racing, and any other races that use similarly designed vehicles. I tend to doubt that it will work with stock-car racing. I'm quite sure it won't work for motorcycle or truck racing.

The key to this idea is something that is known as "down force". Formula One and CART racecars have airfoils that cause the vehicles to be forced harder against the asphalt. This increases the friction between the wheels and the road, and allows higher-speed cornering. However, I consider the most interesting thing about "down force" is that the magnitude of this force is greater than the weight of the car! What this means is that if the car is moving fast enough and enters a tunnel, it can literally climb the walls of the tunnel (from airplane terminology: barrel-roll fashion), and drive along the roof of the tunnel, perfectly upside down, and quite solidly contacting the ceiling of the tunnel as it does that! The car's airfoils will let it 'fly'/drive along the ceiling!

Well, that means we can now design some very special race-tracks, which take full advantage of the fact that those cars have lots of down-force....

For starters, let's build a big VERTICAL loop (like roller coasters have), with an inside diameter of about 1681 feet. The circumference of this loop is one mile. The Empire State Building is only about 1400 feet tall, for comparison, so you can easily see that this is going to be a rather expensive proposition. (For less expense, and for proponents of the metric system, a loop diameter of about 1044 feet will have a circumference of one kilometer.) The loop should be wide enough for 5 or 6 lanes of racecars -- but the outermost two lanes (one at each edge of the loop) will be mostly off-limits as acceleration/deceleration lanes. The race begins with cars on a straighaway leading to the loop. They get up to speed, jog to the left, and enter the loop. They STAY on the loop for 100 or 250 or 500 or however-many laps is the race. To make pit stops, the cars exit at the bottom of the loop, left side only, and slow down and pull into the apprpriate pit-zone. The track for the pit zone circles around to rejoin the initial straightaway/acceleration-ramp. Cars may need to be equipped with emergency parachutes. Just drive off the edge of the loop, and pull the rip cord....

This racing loop has several advantages over ordinary tracks. As far as the drivers are concerned, they get to drive STRAIGHT AHEAD THE WHOLE RACE. No turns except at the start of the race, for making pit stops, and for making lane changes while passing other cars in the loop. There's NO WALL to hit! The "stands" for the crowd are incredible - TWO huge 1600-foot-tall and 1600-foot-wide rows of balcony-seats, one facing each side of the racing loop. (The pit-stop track will circle around behind one of these stands.) Anyone at any point (except corner areas of the structure) can see just about the whole race track, with unimpeded view! Obviously the middles of the stands will be the most desired regions -- every part of the racing loop will only be about 850 feet away (allowing for space between the stands and the loop). If each rear-entry balcony/seat/zone is 2 feet wide and 4 feet tall, then 320,000 people can view the race! With absolutely no danger from the race cars!

Well, that was just for starters, folks. Elsewhere on the HalfBakery is an idea for a Moebius roller coster. The down-force of these race cars CAN keep them on a Moebius race track....

 — Vernon, Sep 02 2001

 Fishbone (nothing personal, Vernon, I just think horse racing is far more interesting and car races are a complete waste of gas.....)

Oh, and the car in the tunnel upside down is baked in the movie Men in Black.....
 — Susen, Sep 04 2001

 That was only a movie. A stock car with added airfoils may or may not have enough down-force (but they can do anything in movies). The place I first saw the tunnel thing was a documentary about Formula One cars.

 Anyway, the idea is not about tunnels, it is about unusual (and so far UNbaked) racetracks for cars.

And to some extent car races are not at all a complete waste of gas. Auto companies regularly try out new technologies in race cars before they trickle down to the mainstream marketplace.
 — Vernon, Sep 04 2001

 // This racing loop has several advantages over ordinary tracks. As far as the drivers are concerned, they get to drive STRAIGHT AHEAD THE WHOLE RACE. No turns except at the start of the race...//

 Hmmm... I'm not sure that a race with no turns would be particularly interesting to watch, or all that popular with the drivers, either. You see, if there are no turns then everyone drives at top speed all the time and the winner is the car whose engine revs the fastest. The driver could be a chimp, because no real skill is involved -- just press the pedal all the way down. Barring mechanical failures, the finish order is obvious by the end of the first lap. What's the point of watching the rest of the race?

 With turns, the driver's skill gets involved. A driver must decide when and how much to brake, trying to maintain that delicate balance between speed and control. The skill and judgment of the driver become major factors in the final outcome of the race -- a fact that keeps the really good drivers well paid.

 //There's NO WALL to hit! //

But what about the *ground*? Parachutes can slow a falling object, but not stop one. Even with a very large parachute, the terminal velocity at impact would be high enough to endanger the drivers to a substantial degree.
 — BigBrother, Sep 06 2001

 come on, vernon! you can do better than that. as soon as the cars start moving _up_ the loop, they will lose speed, and since the "down force" is related to speed, they will lose "down force". therefore, a car would not even be able to complete one lap. also, i think you've over-estimated the contribution of the cars' wings to their ability to stay on the ground. there's more involved than just "down force". how about the lift that is produced by the car? how about the friction of the tires to the pavement? reubens barrichello proved this past weekend in belgium that you can still drive an f1 car pretty fast, even without a front wing.

besides, this race would be boring for the specators _and_ for the drivers.
 — mihali, Sep 07 2001

I dunno, mihali...As soon as the cars started dropping off the track from lack of speed, it'd be mildly interesting.
 — StarChaser, Sep 08 2001

 BigBrother, perhaps you don't know, but not too many years ago, they started making and selling parachutes so big they will let a whole light plane (like a Piper Cub) descend safely, in case of engine failure. So I'm sure that if they can do it for airplanes, they can do it for race cars.

 About the straight-ahead, yes, I know that this would make the race more of a technology test than a skill test. But if your car is REALLY faster than all the others, won't you have to do lots of lane-changes to pass them? How many racing accidents are due to inaccurate lane-changes? Next, a personal beef, is that races with turns are almost always asymmetrical. I've always thought that a race with turns should have as many right turns as left turns. (Even LeMans-style races are usually imperfect in that way.) As things are, they actually make different tire sizes for the left side of the car, than they do for the right side of the car, to "match" the asymmetry of turns. It seems to me that when they think tweaks like that are necessary, it is more practical to just build a figure-8 racetrack, with an overpass. Finally, it occurs to me that one of the standard tricks of racing is known as "drafting", and I think that this is NOT a good idea to try on this racetrack. You NEED to be cleaving air, to obtain lots of down-force! So there will be major tactical differences between a race on this track and a race on an ordinary track.

 Mihali and UnaBubba, you should have seen that documentary for yourselves. The math that has BEEN done plainly states that the car can stay in contact with the top of a tunnel while upside down, where aerodynamic down-force (or more precisely in this particular situation, up-force), is the ONLY thing keeping the car in contact with the ceiling. The down-force needed to stay in contact with the vertical portions of the loop is always going to be less than that needed to stay in contact with the upper regions of the loop.

 Next, the average high-speed skyscraper elevator during rush hour, full of people, probably weighs rather more than "830kg plus fuel". The electric motors that lift those elevators have a LOT less horsepower than the engines of race cars. (Yes, I know that the elevators are counterbalanced to some extent. Even without the counterweights, the necessary elevator horsepower is still a fraction of what racecars have available.)

 Another thing, the physics of jet or rocket engines and reaction-gas acceleration is rather different from the physics of wheel-on-road frictional acceleration. Which is the main reason why the just-mentioned elevators work with vastly less horsepower than jets or rockets need.

Also, it is not necessary for a car to ACCELERATE while climbing the side of the loop; it is only necessary to MAINTAIN some minimum speed that ensures adequate down-force. I don't claim to know what that speed is, but I am quite sure, in a straight-ahead-only race, the cars will be able to get up to much faster than that speed on the acceleration ramp, before entering the loop.
 — Vernon, Sep 09 2001

 UnaBubba, on a steep enough slope, under ordinary conditions, the friction between car and road becomes insufficient, and the car will slip downwards for that reason alone. But this is what the airfoils and the down-force prevents: lack of friction.

 Next, you are somehow ignoring the fact that race cars always have special features, compared to ordinary cars. Further, you are ignoring the fact that race cars are often tailored for specific races. I can guarantee that if a racing loop like this is built, they WILL make cars powerful and fast enough to climb that 1600-foot height.

 I don't know how many gears a Formula One car has, but if it can go fast enough in less than top gear, to generate enough down force, then I daresay these cars are already powerful enough for this racing loop.

Personally, I thought the biggest problem with this idea was making sure the gas kept flowing to the engine, no matter what the orientation of the car. But airplane designers solved problems like that (associated with performance flyers) long ago.
 — Vernon, Sep 09 2001

 Vernon: Any decent race car can accellerate at greater than 1g at slower speeds (even many 'ordinary' cars can do so). Unfortunately, the power required for such acceleration increases with speed, and maintaining speed up a vertical climb requires at minimum the same power as accellerating at 1g (ignoring aerodynamic effects; airfriction and the airfoils would probably add another g to the required force).

I don't know what the required speed would be for the airfoils to keep the wheels sufficiently solidly on the ground, but it would most likely be a lot faster than a passenger elevator.
 — supercat, Feb 05 2002

 Let's lay the track down (horizontal) and build it out of some strong, transparent material. Now the crowd can sit outside the track and see in.

 The track needs to be round or oval (or at least we need very large turn radii). The cars need to maintain a high rate of speed, but still safely make pit stops and we need a place from which to start. I propose a wide, flat area of the track that forces all the racers off the walls/ceiling for a few hundred yards. In fact, I'll propose two, diametrically opposed.

Racing strategy might boil down to speed and finding the shortest route through the toriod. Note that there is no inside or outside to the track, so it might be difficult to stop people from passing. Crashes would be spectacular.
 — phoenix, Feb 05 2002

I'm not convinced this idea would work at all, but I reckon putting jet engines in the cars might be an idea. As the friction against the track is reduced when the vehicle is climbing/upside down, then the amount of traction obtained would be reduced, and the vehicle would not be able to go so fast. I assume, the wheels would start spinning as though you were driving on sand or ice, and you'd lose speed and -- ow! On the other hand, jet engines can work vertically; the only problem is the exhaust against the guy behind.
 — pottedstu, Feb 05 2002

Perhaps the cars for this race could be jet-powered, but the engine would power the wheels. THe exhaust could directed out of the top of the car push it against the loop. As for the race being boring because of no steering, if the amount of fuel alllowed was decreased, cars would have to make more pitstops, making for a more constantly changing race.
 — salmon, Feb 05 2002

 supercat, if I recall correctly, the power required to overcome wind resistance goes up as the cube of the increased velocity. So, if it takes less than 20 horsepower to cruise at 60 miles per hour (I'll simply assume 20), then tripling that speed to 180 mph means that 3x3x3x20, or 27x20, or 540hp is required to cruise at that speed. Practically any race car has that much power available (and I'm sure I've overstated the power required; I think a reasonably aerodynamic car can cruise at 60mph using only 12hp or so).

 Next, I'll assume that 200 hp is sufficient to accelerate a car at 1G. That power is ADDITIVE only, so if the car is trying to climb a vertical wall at 1mph, only 200hp is needed to overcome gravity (assume for sake of argument here, no worry about friction between wheels and wall), and if the car is trying to climb a vertical wall at 180mph, using air resistance to generate sufficient down-force, then 540+200hp, or 740hp is needed to overcome gravity. This is not beyond the bounds of existing Formula One race cars, I think.

 Obviously the preceding is an estimate. If a higher speed is needed to generate enough down-force, or a different amount of power needed to accelerate the car at 1G (overall mass of sufficiently powerful engine being most important factor), then the estimate can be adjusted accordingly. I shall maintain that this idea is workable.

 phoenix, you would defeat the uniqueness of this idea, and lose half the capacity to accommodate ticket-buyers.

pottedstu and salmon, certainly jet engines would work. However, you are simply specifying an alternate way to generate sufficient horsepower. I already mentioned in a prior annotation something about cars being specifically built for particular races, as needed, so you've not really added anything new.
 — Vernon, Feb 27 2002

 Nonsense.

 How far back from the track are the upper levels of the stands? That is, how steep are these stands (which are taller than the Empire State building)? Or are are you going to build skyscrapers on either side? Skyscrapers with enough elevators to handle 320,000 entering/exiting? Oh, and you can't sit with your family since "...each rear-entry balcony/seat/zone is 2 feet wide and 4 feet tall...". Ouch. Watch your head. Don't jump to your feet! Then there's vending and bathrooms. Are the "balcony/seat/zone"s glass-fronted? If not, expect debris on the track. And expect to get bonked on the head from the occasional dropped soda.

Take your track ("...with an inside diameter of about 1681 feet.") and lay it down as I suggest. Make it a tube 100' across (so the outside diameter is 200' greater than the inside). Now figure how many linear feet there are on the inside circumference. Add that to the number of linear feet on the outside circumference. Now divide by four (I want to give my spectators plenty of room). How many people can you fit?
Will everyone be able to see the entire track? No. But I doubt there's much to see when you're 1600' feet in the air and the racers are at the bottom of the loop, either. Especially if you can't lean out of your glass-enclosed "balcony/seat/zone".
 — phoenix, Feb 27 2002

 phoenix, each stand can be quite vertical on the side facing the track, and have diagonal supports behind them (sort-of billboard shaped). As a whole, each stand has to be placed sufficient distance from the track to allow room for cars and their parachutes, between the track and the stand. Next, the spectator spacing I descibed was intended more to allow calculation of the size of the potential crowd, than to be a fixed design standard. Probably the cheaper seats would have the spectators packed a lot like described, while the more expensive central seating would be more spacious.

Next, if each seat was glassed in, there would be nothing to stop the builders from putting slightly curved glass in, so that a lens effect lets the viewer see the whole track, with only a little distortion. At least that would certainly be true of the central seats.
 — Vernon, Feb 28 2002

"...each stand can be quite vertical on the side facing the track, and have diagonal supports behind them (sort-of billboard shaped)."
No, they'll have to be 30' or 50' thick (minimum) to accomodate the seating, elevators, bathrooms, stairwells, sprinkler system, vending and hallways to/from the elevators. May as well plan on building thin versions of the Sears Tower on each side of your race track.
 — phoenix, Feb 28 2002

phoenix, I think that if you compare a 50' thickness to a 1600' height and width, then from a distance you might say that the stands would appear somewhat billboard-shaped.
 — Vernon, Mar 01 2002

What happens when I am halfway up the loop and there is a crash ahead?
Raining metal, burning fuel and assorted other "goodies will crash into the drivers below.
Can you say "Yellow Flag"? Anyone at the top of the loop would be in a world of hurt when that flag came out.
 — Klaatu, Dec 18 2003

klaatu, one thing I was careful to specify was "5 or 6 lanes for race cars". This is significantly wider than most race tracks, and should lead to fewer collisions, and also to easier means of avoiding debris (the track won't be so packed with cars). Oh, and since all lanes in the loop are equal length, there is no preferred lane for drivers to fight for space. That means lane changes will almost exclusively be done for passing, and not because a certain lane is the right place to be at certain times.
 — Vernon, Dec 18 2003

I like this idea, but a designing the track as a hoop with an infinite straight results in a boring race track. Now lets build a 1600 foot sphere and run a 3 dimensional track around the interior surface - entry to the track would involve a spiral ascent from the bottom of the sphere - spectators can be arranged into any portion of the interior space, or view through gaps in the sphere or even transparent sections of track. Transparent track sections would create a large amount of additional advertising space on the underside of the cars.
 — Miraz, Dec 19 2003

 Just have the entire racetrtack upside down!

Add lots of corkscrews and the like!
 — DesertFox, May 18 2004

 [Miraz], I think your track is going to cross itself somewhere, leading to Demolition Derby problems.

[DesertFox], An upside down track sounds interesting, but you would have the audience hurting their necks trying to see the race. AND you lose one key feature of this Idea, which is the ability to accomodate a larger audience, with people on both sides of the track-loop.
 — Vernon, May 18 2004

For all those who thought this Idea was unworkable, have you seen a recent "Popular Science" in which they have a longish article about race cars? This idea IS workable!
 — Vernon, Nov 09 2004

 I don't doubt that this would work, or at least that it could be made to work.

Down-force could even add a little spice to standard racetracks. It might be worth while to put an upside-down segment providing a short-cut, so that drivers don't have to complete whole laps. This short-cut would only be two lanes wide, so it would be a battle to get on it.
 — Xenophile, Jun 07 2006

Your physics is fine. This could be built.
 — Voice, Apr 08 2008

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