Roadcar transmissions and differentials to handle 5000 hp?

[g-force_addict]

While most people think Dubai Devel Sixteen 5000 hp claim is BS
http://www.carthrottle.com/post/an-inte ... developer/
What if in the future someone actually builds a 5000 hp roadcar indeed? Such an engine CAN be done specially if using NOS/nitromethane fuel.

What transmissions (gearboxes) and differentials could handle 5000 hp while not overly large and heavy for a car?

Would choices be limited to planetary transmissions as all gear teeth are working all the time?

Could synchronous transmissions be used within a reasonable size and weight?
How large would gears need to be since only a few teeth contact each other at a given time?
Would this totally rule out double clutch transmissions?

Any other unusual transmission designs like CVT, hydraulic, magnetic, etc.?

Would a spur-gear differential design be more resistant at a given weight?
http://en.wikipedia.org/wiki/Differenti ... fferential

[bdr529]

While most people think Dubai Devel Sixteen 5000 hp claim is BS
http://www.carthrottle.com/post/an-inte ... developer/
What if in the future someone actually builds a 5000 hp roadcar indeed? Such an engine CAN be done specially if using NOS/nitromethane fuel.

What transmissions (gearboxes) and differentials could handle 5000 hp while not overly large and heavy for a car?

Would choices be limited to planetary transmissions as all gear teeth are working all the time?

Could synchronous transmissions be used within a reasonable size and weight?
How large would gears need to be since only a few teeth contact each other at a given time?
Would this totally rule out double clutch transmissions?

Any other unusual transmission designs like CVT, hydraulic, magnetic, etc.?

Would a spur-gear differential design be more resistant at a given weight?
http://en.wikipedia.org/wiki/Differenti ... fferential

Even if someone could or would build that car with 5000hp, What are you going to do for tires ?
making an engine and getting that power to the wheels isn't going to be the problem imo, it's getting it to the pavement and with 5000hp I'm sure you'd run out of rubber before you ran out of horsepower, at least with the Bugatti you run out of fuel first

[MadMatt]

I think once you go passed 300kph you should really have wheel spin!

With this kind of power you would have to go with locked axle I believe. I doubt you can find gearboxes rated at this power too, but that is not really my domain so other people will know better. Before looking at double clutch you have to find a gearbox, that is for sure. Unless you find a way to have a twin CVT with clutches (but imagine the size of the clutch)...

[Tim.Wright]

I ran a few quick calcs on this just for fun and I've seen that unless you have a reasonable amount of down force you will be spinning the wheels at 400km/h trying to overcome the drag.

Let that sink in for a while...

[SectorOne]

I ran a few quick calcs on this just for fun and I've seen that unless you have a reasonable amount of down force you will be spinning the wheels at 400km/h trying to overcome the drag.

Let that sink in for a while...

Plenty of supercars now do over 400 clicks without spinning the tires. Assuming this 5k monster has similar drag levels it won´t spin the tires trying to overcome it´s drag at 400 clicks.

It could however probably spin it´s tires if you just nail it at 400 clicks due to the insane amount of power you can transmit to four small contact patches.

[bill shoe]

I can address the transmission part of the question. I agree with Tim.Wright that the car would be traction-limited at 400 kph and 5000 hp. Therefore multiple gears not needed for performance. Just a single-gear direct-drive powertrain. Perhaps an aux electric motor to start the car from rest until the car is moving at a speed that corresponds to the engine's idle speed.

EDIT: I watched the video here- https://www.youtube.com/watch?v=UgwuiWUrQHI
The creator is something like a cross between Elan Musk and Don Quixote.

[megz]

The pro-modified and possibly Top Alcohol drag racing classes in the US run a 3 speed trans if not too mistaken. From what I gather they aren't too far removed from Top Doorslammer and Top Alcohol classes in NZ and Australia.

The engines in this classes are rated to around 3500hp. I don't know how close to the limit the transmissions are in these applications but that is something.

Lenco are the producer of many of the transmissions in use amongst these high horsepower applications, see here: http://www.lencoracing.com/TheLENCOfami ... sions.html

[MadMatt]

I ran a few quick calcs on this just for fun and I've seen that unless you have a reasonable amount of down force you will be spinning the wheels at 400km/h trying to overcome the drag.

Let that sink in for a while...

Do you have more details on your simulation? Friction coefficient, 4WD or 2WD, etc.

[Tim.Wright]

It wasn't a simulation, just a hand calc. Assuming RWD

They mentioned 560km/h as a top speed in a video I found which with 5000hp implies a Cd of 0.77 (which seems very high but anyway).

On a second look its losing traction at closer to 500km/h (not 400) at which point the drag force is about 14kN.

Assuming a mu of 1.1 and a R% of 50%, car mass 2000kg you only have about 10kN of traction force available from the tyres.

Honestly I didn't waste a lot of time on this...

[autogyro]

Why?

[g-force_addict]

Yes the 0.77 Cd looks quite high as I doubt it will generate that much downforce.

So likely the car real top speed would be actually higher.
Thus tires and safety dictated its 'top' speed and not hp and aero.

The direct drive idea is interesting. If no gearbox can survive 5000 hp then don't use a gearbox at all (direct drive).

[g-force_addict]

I think once you go passed 300kph you should really have wheel spin!

With this kind of power you would have to go with locked axle I believe. I doubt you can find gearboxes rated at this power too, but that is not really my domain so other people will know better. Before looking at double clutch you have to find a gearbox, that is for sure. Unless you find a way to have a twin CVT with clutches (but imagine the size of the clutch)...

Thanks for your reply.
Interesting to hear about CVTs.
Can you please elaborate?

Could CVTs handle such enormous power?
Likely they will use chains (like in the banned Williams F1) instead of rubber belts usually used in roadcar CVTs.

You mentioned twin CVTs.
What did you mean by TWIN? Does that mean two sets of cones that alternate by twin clutches?

[autogyro]

I think once you go passed 300kph you should really have wheel spin!

With this kind of power you would have to go with locked axle I believe. I doubt you can find gearboxes rated at this power too, but that is not really my domain so other people will know better. Before looking at double clutch you have to find a gearbox, that is for sure. Unless you find a way to have a twin CVT with clutches (but imagine the size of the clutch)...

Thanks for your reply.
Interesting to hear about CVTs.
Can you please elaborate?

Could CVTs handle such enormous power?
Likely they will use chains (like in the banned Williams F1) instead of rubber belts usually used in roadcar CVTs.

You mentioned twin CVTs.
What did you mean by TWIN? Does that mean two sets of cones that alternate by twin clutches?

CVT transmissions are only suitable for low power, they all require large energy input to maintain friction drive or cone position and they end up too heavy.
Williams soon found that out as Patrick Head did with the flywheel storage KERS systems they worked on when compared to the battery storage in use.

It is not a problem finding or designing a gearbox for 5000 hp, torque delivery is always limited by the ability of the tyres to maintain traction.
5000 hp is way above any tyres I know of in a car of a sensible weight.
I asked 'why' anyone would want to do something that would not work.

[J.A.W.]

Indeed, since ~1/2 a century ago a 'car' was constructed to transmit power of the like mooted,
- the British Campbell 'Bluebird Proteus' geared turbine LSR machine..

It was driven on the road, but naturally, was not a practicable road car..

[autogyro]

Indeed, since ~1/2 a century ago a 'car' was constructed to transmit power of the like mooted,
- the British Campbell 'Bluebird Proteus' geared turbine LSR machine..

It was driven on the road, but naturally, was not a practicable road car..

A good example but I think you will find that Bluebird used the engine thrust as well as the geared drive system.
Without using thrust I doubt the car would have reached a high enough speed.