Off to the races!


One of our customers writes software for drag racers (see Fox helps drag racer win Microsoft Start Something Amazing Award). His software helps the drag racer keep track of opponent statistics as well as how a car performs from race to race.


 


He invited several people from Microsoft to the NHRA drag races at Pacific Raceways this past weekend. Don Higgins, his brother Dave, his wife Michelle and his son Dan of Crew Chief Pro software were wonderful hosts, showing us neophytes around the racetrack, introducing us to race car legends, and teaching us about the sport. I tagged along as Don made a few stops to visit and help his customers. Of the 900 or so cars in the race, almost half were his customers! He seemed to know everybody!


 


When I was a kid, I used to play with toy cars like Hot Wheels. There were models called Snake and Mongoose. I met Don (“The Snake”) Prudhomme and chatted a little about racing. Wow! A legend in the flesh!. We talked about Microsoft, how software changes people’s lives, and drag racing!


 


He had several semi trucks with his team. We entered a pair of them that were parked very close together, with a wide doorway in between, making a large machine shop. We were given a tour of pistons and rings, cylinders and valves. I held an intake and exhaust valve in my hand. We were told how a Top Fuel Dragster engine was taken apart and put together after a race in 35 minutes! Burning 14 gallons of Nitro methane for a quarter mile race is about 56 gallons per mile! The cylinders are injected with vast quantities of fuel per stroke, while the engine goes to 9000 RPM with no gear shifting.


 


We watched and felt a few of the races from near the starting line. The deafening roar of a drag racer going from 0 to 340 MPH to race a quarter mile in less than 5 seconds was unbelievable. It literally shakes your body as they go. We were given the red carpet treatment: watching the drag races from the comfort of air conditioned suites at the Tower was quite comfortable, considering the almost 100 degree weather. We met a few representatives of the NHRA (National Hot Rod Association) who were very gracious and generous, giving us the red carpet treatment.


 


About 13 years ago I attended a Visual FoxPro Developer Conference in Orlando. One of the attendees happened to work at NASA and was able to get a pass to let us see the shuttle launch up close. At the time, “close” meant around 3 miles or so. I remember Tom Rettig was with our caravan of 2, waiting for the earth shaking roar of the shuttle. We were disappointed, however, when the countdown stopped with about 10 minutes left, so we missed the launch. I’m told that the shuttle launch really shakes the ground.


 


Question: how does the roar of a Top Fuel Dragster compare with the roar of a space shuttle? Of course we can get *much* closer to a drag race, and there are a few thousand races throughout a day, a couple per minute.


 


From the web site, a drag racer gives the driver about 6 Gs of acceleration: that’s really being plastered into the seat! A Space Shuttle Astronaut gets about 3 Gs (for quite a bit longer than 5 seconds).


 


With some simple back of the envelope calculations using MKS metric system: (Meters, Kilograms, Seconds) and assuming constant acceleration for simplicity:


 


Time = t = 5 seconds


Top Velocity = v = 300 MPH = 300 * 5280/3600/3.2 = 137.5 Meters / Second = 2d/t


Distance = d = one quarter mile = 5280 Ft/Mile / 4 / 3.2 Ft/Meter = 412.5 Meters = vt/2 constant acceleration


 


Car Acceleration = a = v/t = 137.5/5 = 27.5 M/sec^2


Force = F = mass X acceleration (from Newton’s second law) = ma


Work = Force X Distance =mad


m = 2000 pounds = 900 Kg


Power = 7000 HorsePower (on web site) = 7000 Hp * (746 W/Hp) = 5.2e6 Watts


Power = work / unit time = mad/t = 2md^2/t^3


 


m=900


v=137.5


t=5


d=412.5


?2*m*d^2 / t^3 / 746


 


This yields 3284 horsepower.


 


Acceleration due to gravity = 1 g = 9.8 M/sec^2


 


So my calculation shows 27.5 / 9.8 = 3 g’s and 3284 horsepower experienced by the driver assuming constant acceleration. There’s probably a lot more acceleration at the start: the speed time graph is probably not a strait line.


 


 


Many thanks again to Don Higgins and his family!


 


See also


SQL Select helps tune a car engine


 


 


 


 


 

Comments (8)

  1. Just one minor correction. I’m pretty sure Don’s brother is named Dave.

    Tamar

  2. Calvin_Hsia says:

    Yes, Tamar..Thanks for the correction. I’ve edited the text. Sorry Dave!

  3. Don Higgins says:

    Thanks Calvin.  I got a kick out of watching you jump everytime a car sprinted down the track.

    Your calculations are great, however they assume constant acceleration which is not the case in our sport.

    A Top Fuel Drag Racer will actually create most of his speed in the first half of the track.  The national record is 4.420 seconds and the speed record is around 337 Miles Per Hour all in 1320 feet.  

    The interesting fact however is that it only takes 3.000 seconds to reach 282 miles per hour at half track (660 feet from the starting line) on the 4.420 second run.

    Thanks for coming, we really enjoyed meeting everyone.

  4. The shuttle is MUCH bigger and shakes things MUCH more than a drag racer. I live not far from where the shuttle’s Solid Rocket Boosters (SRBs) are manufactured. These are the engines that acutally lift the shuttle into orbit. Think back to the Challenger explosion and the cause being the O-ring seals. These O-rings are part of the SRB.

    Periodically, and SRB is bolted horizontally to a platform and test fired. You can feel the ground shake for 30+ miles around and seismographs actually record the tremors. This is only from one booster. The shuttle uses two for lift off.

  5. Don Higgins says:

    Craig,

    You are correct about the shuttle boosters.  They are more millions of times more powerful than our 8,000 HP race engines.

    We have seismographs at the races also, in the stands they record 3.8 on the scale when 2 Nitro cars launch.  They have been as high as 4.8 on the starting line.

    Of course I can drive a drag race car, neither of us will ever drive the shuttle.