The push vehicle (every little bit helps)

[tallguy]

This may seem quite trivial, but here goes anyway.

As in drag racing, there are a few important things important to the performance of a land speed racing vehicle, including
(but not limited to) mass, power, traction, and aerodynamics.

Typically, land speed racing involves a push vehicle that is allowed to push the race vehicle at the start of its run.  The
amount of pushing allowed may vary depending on the rules.  I once read that there is a distance limit of 300 meters, but I also seem to remember that (perhaps based on the rules of a different sanctioning organization) the limit is 50 mph.  In either
case, the distance beyond that limiting distance/speed provides an opportunity for the race vehicle to accelerate under
its own power, rather than being further helped by the push vehicle.

It should be clear that if the allowed self-powered distance is maximized, the race vehicle may benefit from every little bit
of available distance, provided that acceleration is still happening at the end of the timed part of the run (i.e., timed mile
or timed kilo).  Therefore, the more aggressively the push vehicle can do its job, the more performance should be available
for the race vehicle if it is set up in such a way that it doesn't lack power, traction, slipperiness, ability to rev, and adequate control to be still accelerating at the end of the timed part of the run.

Therefore, the push vehicle, if optimized, should be very powerful, relatively light, relatively aerodynamic, while having sufficient traction to maximize the speed of itself and the race vehicle within the allowed push limit.

I can imagine a push vehicle with a huge (low-speed) spoiler, or fan(s) or a suction area (a la the famous Chaparral at
Laguna Seca, decades ago) pushing the vehicle down to help provide traction, along with a huge powerful engine that
is not necessarily intended to last a long time.  I also don't know how much difference it would make to most land speed runs if the gain in available self-powered distance is just a few yards.  But it could make a difference.  I welcome comments about this.

[MAYOMAN]

The Blue Flame used a push vehicle (Dana Fuller?s van) to assist in setting the FIA world land speed records for the flying start mile and kilometer in 1970. The rocket consumed 2,000 pounds of propellant in 20 seconds. While the rocket was designed to produce 22,000 pounds thrust for proposed supersonic record runs, Goodyear limited our top speed to under 700 miles per hour in 1970. So, the rocket was detuned to 16,000 pounds thrust. Problems while on the salt flats further limited our thrust to 13,000. The Blue Flame was operated at full thrust for 20 seconds, turning off in the middle of the mile timing zone. So, it accelerated for the first half mile and decelerated the final half mile. We needed more acceleration time to achieve the FIA world record speeds. Pushing the car up to around 50 miles per hour allowed us to burn the rocket longer at the highest speeds. The push actually produced another 22 miles per hour for the mile and kilometer timed speeds. This process was permitted by the ACCUS/FIA timing officials in 1970.

[MAYOMAN]

The point here, is the 2 seconds propellant used to go from 0 to 50 miles per hour was used at the high speed end of the burn. By the way, the peak speed we measured in the mile timing zone was 666 miles per hour. We kept our promise to Goodyear not to go 700 miles per hour.

[MAYOMAN]

This was Gary's IP view of the speedometer.

[jimmy six]

Over the years I have watched a lot of blown fuel cars using solid blocks start on the the line and push to the 1 mile so they could get the the 3 for timing I dont believe any were pushed over 50 mph. I have also witnessed supercharged push streamliners at least to the 1 mile as fast as they could go..

[Stainless1]

We push to 30-40 MPH is the shortest distance possible...  the driver lets the clutch out and pushes the loud pedal when the car hits 35... the push continues until the car pulls away... the Bockscar accelerates a lot faster than the push truck.
I think you might get a visit from Lee if you push past the first 1/4 mile marker although there isn't a published rule that I am aware of.

[Ro Yale]

We push our roadsters up to 50-60mph. Depending on the gearing. Usually by that speed we can accelerate faster than the push vehicle. In the diesel streamliner we pushed to 30mph because of the torque of the diesel allowed us to accelerate earlier. You can push all the way the first mile. But there really isn't any need to do this.

[jdincau]

I always pushed as fast and hard as the track would let me. I just told the driver to pull away when he was ready. The race car could always out accelerate the push truck.

[71GSSDemon]

Not to hyjack, but this is good information.  The push itself.  What is everyone's process?  I see a couple above.  I have heard of people having their car in gear with clutch out and allowing the push truck to push to a desired rpm; then get on the gas.  I will hopefully be figuring this out in 2026.

[fissionspeed]

I do often fantasize about a AA blown fuel push truck for my little D/minitruck for a little kick off the line

[desotoman]

I would not worry about a regular type push vehicle unless you are running a vehicle so under powered or the motor so fragile that it might blow up before it ever gets to the timing lights. JMO. 

I pushed my old Street Roadster off at El Mirage with my 1997 Dodge Diesel Truck with a compound low gear 5 speed stick transmission using 2 gear which topped out at around 20 mph. When I hit the governor in that gear I would honk the horn for the driver to put the roadster into gear and accelerate away from the truck. The roadster was running an automatic transmission without a Torque converter and that is why we had to push it in the first place. The roadster was not very fast at 163 mph but it would hit that speed at the mile, yet we had another Third of a mile to go. For the fun of it we tried different gearing etc. but that was going to be the top speed for that motor in that roadster period. So we hit our limit on aero vs. horsepower at El Mirage.

Tom G.

[Stan Back]

We always used my towing vehicle, a 3/4-ton Chevy with a 5-speed (really usually 2nd, the 1st is a granny) 6-litre motor.  Have the roadster started, push as hard as you can. Get away from the truck as soon as you can as we won't push again.

El Mirage seems three blocks long, so you better be accelerating rather that cleaning out the engine.

[tortoise]

If I remember right, the fastest wheel-driven run ever was without a push.

[AJR192]

The Beast pushed down to the 2 at either WoS or the Finals this year. Don't remember which meet. Just so they could run to the 5.
It was a disappointment for those of us at the line and a huge waste of time for the other racers waiting to run.
Is there really a rule?
If so why do certain teams get to circumvent it??
Maybe there should be a line at a certain distance from the 0 marker and if your vehicle is still on the push truck your run does not count.
Even the playing field.....

[John Burk]

I remember in 1960 Tom Beaty telling about pushing Art Arfons with Tom's blown Olds '40 sedan delivery with Arfons helper Snyder? as a passenger . Arfons accelerated and Beaty pulled alongside with Snyder with his movie camera going and exclaiming . Fast sedan delivery .