F1 physics on the moon

[GoatMonkey]

So, we were watching F1 qualifying while sitting in a bar tonight. The crazy drunk talk that came up was, what would happen if you had an underground F1 race on the moon with regular earth atmosphere, but moon gravity. Would the cars corner faster? How would mechanical vs. aerodynamic grip change? Would they be faster around a track assuming it was an exact replica of an existing earth track?

 

[Sluggo]

Yeah, so if the moon is on a treadmill and trying to take-off...

 

[Black88GTA]

Less gravity = less total downforce = less grip = slower cornering = slower lap times.

My thoughts.

 

[PlasmaBomb]

Lunar gravity is 1/6 that of Earth's. Thus the 605 kg (minimum weight) F1 car would only weight ~ 101 kg

At top speed the aero develops ~ 1200 kg of downforce. Therefore the total force of the tyres on Earth would be ~1805 kg, or three times the weight of the car. On the Moon the force would be ~ 1300 kg (about 28% less force), the lesser force should result in a slightly higher top speed due to less rolling resistance, however when it comes to a corner you are going to have substantially less grip. Lets say the corner is sufficiently fast that the aero is generating 50% of its maximum downforce - 600 kg. On Earth you will have a tyre load of ~ 1205 kg, whereas on the Moon the load would only be ~700 kg (or a massive 42% less). The result would be that your corner speeds will suck and kill your laptime. Of course you could increase the aero on the car, but since F1 cars already have high coefficients of drag (Cd), and aero is not that efficient at generating downforce, you would end up with massive amounts of drag, which would kill the top speed (think massive Pikes Peak aero). The other problem is that gaining that amount of downforce wouldn't be achievable within the rules, so what you would end up with would no longer be an F1 car.

What about the lack of weight allowing the car to accelerate faster??
Oh yeah F= ma
A given force will produce a greater acceleration if the mass is lower... the problem is we are talking about weight. Weight = mass x acceleration due to gravity. Thus while on the Moon you weigh less, your mass remains unchanged. So going to the Moon won't give you super turbo acceleration...

Sorry for the wall of text.

Cliffs:

Q) Would an F1 car go faster on an underground exact replica of a track on the moon?
A) No

Edit: removed apostrophe on Pikes.

 

[PlasmaBomb]

In case anybody doesn't know Pikes Peak -

Video ~2:35 for external car shots.

 

[halik]

It would say it would make for slower laps for a couple of reasons:
1) slow corners would get REAALY slow for lack of traction
2) acceleration will suck, again lack of traction
3) top speed will still be limited by aero

 

[halik]

Originally posted by: PlasmaBomb
In case anybody doesn't know Pikes Peak -

Video ~2:35 for external car shots.

THAT IS FUCKING AMAZING

 

[Kntx]

I guess the bigger question is... what is the ideal gravitational field in which to hold an F1 race?

edit: for lowest lap times

 

[IronWing]

Underground car racing on the moon? Now we have a reason to colonize the moon. With low gravity, tracks could have corkscrews and loop-de-loops. Watch as Steve Reeeeeeve jumps 456 school buses!!!

 

[mwmorph]

Hold on, am I going crazy here?

How are you guys thinking that a car has ANY chance of going slower?

Less weight= less grip needed for cornering.

Furthermore less weight= more favorable tire load curve so a 1/6 weight F1 car would have more than 1/6 the tire grip.

Add in the full amount of aero downforce grip and the total grip v.s. weight ratio becomes much, much more favorable on the moon.

Lower mass also increases acceleration and also the slightly lower friction from the tires would increase top speed a bit too.

So F1 cars would be faster in every respect on the moon.

 

[IronWing]

Originally posted by: mwmorph
Hold on, am I going crazy here?

How are you guys thinking that a car has ANY chance of going slower?

Less weight= less grip needed for cornering.

Furthermore less weight= more favorable tire load curve so a 1/6 weight F1 car would have more than 1/6 the tire grip.

Add in the full amount of aero downforce grip and the total grip v.s. weight ratio becomes much, much more favorable on the moon.

Lower mass also increases acceleration and also the slightly lower friction from the tires would increase top speed a bit too.

So F1 cars would be faster in every respect on the moon.

Hmmm, it might be a wash. While the gravitational weight of the car is reduced, the momentum is not. So the same force is needed to change the car's direction on the moon as on earth. If the wing is the primary source of normal force affecting friction then your analysis is likely correct.

 

[Kirby]

Originally posted by: halik

Originally posted by: PlasmaBomb
In case anybody doesn't know Pikes Peak -

Video ~2:35 for external car shots.

THAT IS FUCKING AMAZING

Damn. Is that the wastegate making all that noise when he slows down and changes gears?

 

[halik]

Originally posted by: nkgreen

Originally posted by: halik

Originally posted by: PlasmaBomb
In case anybody doesn't know Pikes Peak -

Video ~2:35 for external car shots.

THAT IS FUCKING AMAZING

Damn. Is that the wastegate making all that noise when he slows down and changes gears?

Open wastegate is INCREDIBLY loud when you step on it, what you're hearing there is either turbo flutter or the antilag system dumping compressed air straight into the exhaust

 

[PlasmaBomb]

Originally posted by: mwmorph
Hold on, am I going crazy here?

Yes you are crazy

How are you guys thinking that a car has ANY chance of going slower?

Physics

Less weight= less grip needed for cornering.

Nope. See the "will it accelerate faster". Newtons First Law - Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed.

The cars inertia means that it wants to go in a straight line. The tyres need to apply a force to get the car to turn.

Newton's second law tells us that the force equals the mass x acceleration. While the weight of the car decreases on the moon, its mass remains constant. Therefore the force needed to get a car round a corner remains constant regardless of the cars weight.

F = d(mv)/dt

Don't forget that even if the car maintains its speed round a corner it is accelerating since velocity is a vector.

Furthermore less weight= more favorable tire load curve so a 1/6 weight F1 car would have more than 1/6 the tire grip.

I didn't want to get into the complex mechanics of tyres... the lateral load a tyre can sustain is dependant on the vertical load, and it is indeed non-linear. The amount of grip also depends on the amount of tyre slip. It is a simplification but less vertical load results in less grip. Less grip = less corner speed = slower lap time.

Also you won't really be able to use Earth rubber on the Moon, you will need different compounds. Since their is less weight involved the tyres will generate less heat, which means that going flat out will be difficult. See Buttons performance in qualifying when he struggled to get his tyres up to temperature.

As halik said lower grip will result in more wheelspin, which means the tyres won't last as long. If you use softer tyres to minimise wheelspin and increase grip you will need to stop more frequently to change tyres, which gives an advantage to the Earth F1 car.

Add in the full amount of aero downforce grip and the total grip v.s. weight ratio becomes much, much more favorable on the moon.

The mass of the object determines how difficult it is to turn, not its weight. See above.

Lower mass also increases acceleration and also the slightly lower friction from the tires would increase top speed a bit too.

See my first post.

So F1 cars would be faster in every respect on the moon.

Nope.

 

[PlasmaBomb]

Originally posted by: halik

Originally posted by: PlasmaBomb
In case anybody doesn't know Pikes Peak -

Video ~2:35 for external car shots.

THAT IS FUCKING AMAZING

Thanks :beer:

 

[Savij]

Originally posted by: mwmorph
Hold on, am I going crazy here?

How are you guys thinking that a car has ANY chance of going slower?

Less weight= less grip needed for cornering.

Furthermore less weight= more favorable tire load curve so a 1/6 weight F1 car would have more than 1/6 the tire grip.

Add in the full amount of aero downforce grip and the total grip v.s. weight ratio becomes much, much more favorable on the moon.

Lower mass also increases acceleration and also the slightly lower friction from the tires would increase top speed a bit too.

So F1 cars would be faster in every respect on the moon.

Not quite...less MASS means less grip needed. You can get away with saying less weight on earth because gravity is the same everywhere on the planet. You should really be saying less MASS=less grip needed for cornering

Even though the car weighs less on the moon, you are still trying to force the same amount of mass to change direction...to accelerate sideways...but your tires have less downforce on them so they won't be able to exert as much force.

The aero could make up for it...I'm not sure how much of the downforce is from weight vs the aero...no matter what, reduced gravity is bad for cornering at lower speeds...reduced mass is good for cornering at all speeds.

 

[mwmorph]

Originally posted by: Savij

Originally posted by: mwmorph
Hold on, am I going crazy here?

How are you guys thinking that a car has ANY chance of going slower?

Less weight= less grip needed for cornering.

Furthermore less weight= more favorable tire load curve so a 1/6 weight F1 car would have more than 1/6 the tire grip.

Add in the full amount of aero downforce grip and the total grip v.s. weight ratio becomes much, much more favorable on the moon.

Lower mass also increases acceleration and also the slightly lower friction from the tires would increase top speed a bit too.

So F1 cars would be faster in every respect on the moon.

Not quite...less MASS means less grip needed. You can get away with saying less weight on earth because gravity is the same everywhere on the planet. You should really be saying less MASS=less grip needed for cornering

Even though the car weighs less on the moon, you are still trying to force the same amount of mass to change direction...to accelerate sideways...but your tires have less downforce on them so they won't be able to exert as much force.

The aero could make up for it...I'm not sure how much of the downforce is from weight vs the aero...no matter what, reduced gravity is bad for cornering at lower speeds...reduced mass is good for cornering at all speeds.

You're right i went back to study the equations. .cf is affected by weight but momentum is affected only by mass. It would not be like strapping aerodynamic aids and a 650hp motor to a go kart with super tires.

The cars would probably be slower, less grip, same mass to overcome, even with the lighter weight. I think true top speed would still be higher but acceleration and cornering would be slower sine you still have the same mass to overcome, but actual grip in n/m would be lower.

 

[exdeath]

Are we seriously discussing aerodynamics and factoring down force racing on the moon where there is no atmosphere?

Forget the tires and the weight, most of the forces in those cars come from air flow.

The cars would no doubt be faster due to lack of drag, but the turns would have to be several orders of magnitude wider. They would be sliding hundreds of feet sideways all over the place.

Assuming they have air tanks for the engines in the first place.

Also they wouldn't run for more than 5 mins tops before the cooling systems were saturated and unable to dissipate heat without a surrounding medium to carry it away.

Numerous problems here, tire grip is the least of your worries.

 

[PlasmaBomb]

Originally posted by: exdeath
Are we seriously discussing aerodynamics and factoring down force racing on the moon where there is no atmosphere?

Forget the tires and the weight, most of the forces in those cars come from air flow.

The cars would no doubt be faster due to lack of drag, but the turns would have to be several orders of magnitude wider. They would be sliding hundreds of feet sideways all over the place.

Assuming they have air tanks for the engines in the first place.

Also they wouldn't run for more than 5 mins tops before the cooling systems were saturated and unable to dissipate heat without a surrounding medium to carry it away.

Numerous problems here, tire grip is the least of your worries.

an underground F1 race on the moon with regular earth atmosphere

Thanks for trying...

 

[SonicIce]

Originally posted by: exdeath
Are we seriously discussing aerodynamics and factoring down force racing on the moon where there is no atmosphere?

Forget the tires and the weight, most of the forces in those cars come from air flow.

The cars would no doubt be faster due to lack of drag, but the turns would have to be several orders of magnitude wider. They would be sliding hundreds of feet sideways all over the place.

Assuming they have air tanks for the engines in the first place.

Also they wouldn't run for more than 5 mins tops before the cooling systems were saturated and unable to dissipate heat without a surrounding medium to carry it away.

Numerous problems here, tire grip is the least of your worries.

lol. op said on the moon with regular earth atmosphere

 

[sandorski]

Just make the underground Moon track a complete Tube and not worry about it.

 

[jaha2000]

Lets not forget bumps either. Imagine what would happen if you hit a rumble strip in moon gravity at speed!

 

[IcePickFreak]

I agree that straight line acceleration would be quicker, given that the tires could provide enough traction with the reduced weight. Think of a pick-up truck - less weight in the rear and it's easy to smoke the tires because of less weight on the tires. I also agree turning would be slower, unless you increase down-force. Of course this would take away the advantage you had on straight-aways. In the end, it's not really going to change the physics, just were the parts of the equation come from (ie. using air resistance for more downforce vs. having earths additional gravitational pull to help).

I think you could go quicker if you had a stronger gravitational pull (again with the same atmosphere as earth) to the point where you wouldn't need to create extra downforce with wings/spoilers, as they create extra drag to provide the same amount of downforce you would automatically have with the stronger gravitational pull.

 

[GoatMonkey]

This is still interesting even though I'm not drunk anymore. Great responses BTW.

The thing that is interesting is that in the formula:

acceleration = Force / mass

The force being applied to the tires from the engine would be the same, but the force of gravity pulling the car down is reduced, and the force from air resistance is the same.

It seems like once the car got moving fast enough that the force being applied to the tires could no longer overcome the traction of the tires that the acceleration would increase, up until the point where wind resistance prevents if from going any faster. So, maybe the acceleration is reduced up to some point, let's just say 100 mph or so, just because the tires don't have enough grip anymore. Then as the increased downforce from the wings takes affect, and torque of the engine no longer overcomes the grip of the tires it seems like the acceleration would increase. Just on a straight line, billiard board smooth road with no bumps or hills.

 

[Pacfanweb]

I'd like to know how you wouldn't accelerate faster on the moon, with all other things being equal except less weight.

On the average car, every 100lbs you take off the car is approximately .1 drop in 1/4 mile time.

So if you have a 400hp car that weighs 3000lbs on Earth, but weighs say, 2500lbs on the Moon but still has the same 400hp, I don't see how it's not going to be .5 quicker on the Moon...maybe even more, since there's less drag from the atmosphere, too.