Dragster Question

[Midlife]

We all know and love dragster cars, but I've never known the answer to this question:

Why is the wheelbase so long? In particular, what is the advantage for having such a long nose for this racing application when there is nothing much up front to prevent the wheelbase from being shortened (ala funny cars)?

 

[BobV]

Couple of reasons come to mind...

1) Stability. A longer wheelbase will be more stable at high speeds, tending to keep the car going straight. Look at how much "smoother" a Top fuel dragster looks compared to the shorter wheelbase funny cars.

2) The longer chassis flexes and provides smoother weight transfer to the rear tires. Some of the energy at launch is absorbed by the flexy chassis - lots of leverage out there 25' away from the rear tires (even considering the relatively light weight). These make SO much power that they can't apply it all instantaneously, so the chassis and slipping clutch help smooth the delivery.

3) With the solid mounted rear axle, torsional forces would unload one tire even easier than our cars with suspension. The extremely long, flexible chassis absorbs torque, giving more even side-to-side loading of the rear tires.

 

[66gt350]

Bob hit it on the head...The long wheelbase helps the dragster keep its course and flexes at launch. The flex of the chassis allows some of the energy of the launch to be absorbed which helps the dragster gain traction.

 

[Flysure1]

More leg room maybe?--lol, I was not sure either but I would have guessed stability, those altered class cars look like they would be tough to keep straight and they are not as fast as dragsters.

 

[66gt350]

A guy down in SoCal put a pumped up 454 in a VW bug that ran somewhere around 9 sec. The back tires were so wide, that they almost rubbed each other in such a small bodied car. He said that it scared the crap out of him, since it was so squirrely going down the track. No thanks!!!

 

[Midlife]

Thanks for the reasonable discussions. I would have thought that the torque/flex issue would solely be from the engine frame/saddle backwards, and the front wouldn't do much at all. Doesn't the front lift up entirely upon start due to the torque of the engine applied to the rear wheels? If so, all the flexing is done with the front up off the ground...anyway, that was my thinking (right or wrong).

 

[Sacbill]

Thanks for the reasonable discussions. I would have thought that the torque/flex issue would solely be from the engine frame/saddle backwards, and the front wouldn't do much at all. Doesn't the front lift up entirely upon start due to the torque of the engine applied to the rear wheels? If so, all the flexing is done with the front up off the ground...anyway, that was my thinking (right or wrong).

Properly set up, this is about how far a Top Fuel car will lift at the start before the wheelie bar pushes it back down:

At top speed, the flex is spread along the chassis, causing a visible arc in the body. The car is like its own leaf spring: