Hypothetical question

[Poorboy_racer]

A recent discussion:
You have a car that runs 16 second standing quarter miles.
You get another identical car that also runs 16 second standing quarters.
You weld the front of one car to the back of the other, forgetting logistics like cooling for the second car etc, you link the accelerators and gear shifts. Lock the steering of the second car.
Would the combination of cars be slower than 16 seconds over the quarter?
Faster over the quarter?
Or the same?

1 Friend says faster as first car cuts the air for the second.

Other says depends on power to weight of cars. If the power to weight is low the two engines won’t make up for the increased inertia getting it off the line. With a high power to weight (should run better than a 16 in the first place) the engine power would more than make up for the increased weight/inertia.

Me? I think leave it to Mythbusters.

[39ClevoUte]

Friend 1

[Charliewool]

But............. WILL A PLANE take off if it was on a giant conveyor belt going backwards at a speed realtive to the planes thrust?

[simon varley]

no change. F=ma you've doubled the force but you've doubled the mass too. simplistically

[CoupeKing]

3 2 1...sick of hearing that, just press the button when the rest of the set least expects it.

[ford man xf]

Depends if the flux capacitor is in the first or the second car?

[CyberWasp]

Now you made my brain hurt.....I am going to go and lay down.

[Crazy Dazz]

Originally Posted by Poorboy_racer

1 Friend says faster as first car cuts the air for the second.

Correct, its called bump-drafting.
You don't even need to weld them together.
First car will be faster as the 2nd car slipstreaming will reduce its drag.

That said, over a quarter the difference would be negligible, as aerodynamics play only a minor part in such races.

[Peter B - CV8]

Originally Posted by Crazy Dazz

Correct, its called bump-drafting.
You don't even need to weld them together.
First car will be faster as the 2nd car slipstreaming will reduce its drag.

That said, over a quarter the difference would be negligible, as aerodynamics play only a minor part in such races.

Wouldn't it be the other way around ?? ie the leading car (no1) is copping all the frontal drag - therefore allowing the car behind (no2) to have a slightly increased speed, until it overtakes at which point the roles are reversed.

[EgoFG]

If the are the same then it could theoretically be faster.

Double the power, double the grip
Double the weight, double the aero drag on the sides, but the front and rear aero drag are not doubled.
There will be less total aero drag.

But if the cars were not identical ... and had different gear change points .... now that would be fun.

[Poorboy_racer]

So if one car were faster than the other which car goes in front?
Faster one or slower one?