Axle height

[IAE Racing]

Quote:
Originally Posted by Obsessedderbydad
Then why do top fuel dragsters have a higher rear wheel?

I was just wondering because of the Potential Energy formula. The higher the weight the more PE, whats = speed.

Why does a farm tractor have a higher rear wheel?

While no expert on top fuel, similarities exist between the dragster and the tractor. The goal of both pieces is getting the most work done effeicently. Horsepower transfer to the ground in both cases relies on friction. With the dragster, the car has way more power than in has ballast. Taller, wider tires put a larger footprint to pavement creating more grab-friction. If the wheel is slipping, the extra horsepower is being wasted so wheel slippage is bad. the front wheel are small a: to keep the as much weight reward as possible and b: to reduce friction ie narrower tread on a cheetah 7.5mm than a stock 8.3mm . Not to increase potential energy but to put more ballast on top of the drive tires. think the same way with COM on your derby car. As much weight to the back while still being able to steer.

Same goes for a two wheel drive tractor (rear wheels drive). A properly ballasted two wheel drive tractor is 30% weight to the front, 70% rear. If you do not have enough ballast on your drive tires, your wheel slip will be excessive and you waste horsepower, and not get any work done. Also. a Larger radius wheel has less rolling resistance. That's why the Eliminator and Unlimited class has a max diameter of 31mm. By theory, a 35mm OD should be faster due to less rolling resistance.

Sorry to carry on, Hope it answers your question.

 

[bracketracer]

Question... If you have the DFW lower than the rears, wouldn't this give you less potential energy since the majority of the weight is more forward now because of the DFW being lowered? Or am I thinking about this backwards?

Unless I missed what you mean.......if you drill your axles say a half inch lower to raise the car an extra half inch, you gained no PE, because when the car hits the flat the weight is STILL a half inch higher so it dropped the same distance down the hill as before.

 

[Guest]

Quote:
Originally Posted by Obsessedderbydad
Then why do top fuel dragsters have a higher rear wheel?

I was just wondering because of the Potential Energy formula. The higher the weight the more PE, whats = speed.

Why does a farm tractor have a higher rear wheel?

While no expert on top fuel, similarities exist between the dragster and the tractor. The goal of both pieces is getting the most work done effeicently. Horsepower transfer to the ground in both cases relies on friction. With the dragster, the car has way more power than in has ballast. Taller, wider tires put a larger footprint to pavement creating more grab-friction. If the wheel is slipping, the extra horsepower is being wasted so wheel slippage is bad. the front wheel are small a: to keep the as much weight reward as possible and b: to reduce friction ie narrower tread on a cheetah 7.5mm than a stock 8.3mm . Not to increase potential energy but to put more ballast on top of the drive tires. think the same way with COM on your derby car. As much weight to the back while still being able to steer.

Same goes for a two wheel drive tractor (rear wheels drive). A properly ballasted two wheel drive tractor is 30% weight to the front, 70% rear. If you do not have enough ballast on your drive tires, your wheel slip will be excessive and you waste horsepower, and not get any work done. Also. a Larger radius wheel has less rolling resistance. That's why the Eliminator and Unlimited class has a max diameter of 31mm. By theory, a 35mm OD should be faster due to less rolling resistance.

Sorry to carry on, Hope it answers your question.

Thanks IAE!
I found that fascinating!
Over the weekend I watched a bit of a tractor pull.
The first thing I thought was "ya gotta love America"
Next I started to dissect the oddities of the machine for their "reason for existing".

 

[Safer Racer]

I believe you would want the car flat and level. If the front of the car is higher the Neg rear cant on the rear wheels turns into toe out. If the front is lower then the rear tires get toed in.