Shockwave is a Peterbuilt semi-tractor powered by three turbojet engines that has been entertaining crowds at air shows, truck shows and drag racing tracks across the U.S for over 30 years. The Shockwave was the brainchild of the aptly named Les Shockley who built the truck in 1984 and drove it at events before passing it on to his son Kent. Since then the Shockwave has been acquired by another father/son team Neal and Chris Darnell who added the crowd pleasing afterburners that juiced up the ride to its Guinness Book of World Records performance and spew flames out the back and up the exhaust stacks. It is a visual experience not to be missed!
Unleashing 36,000 Horsepower
If you spend enough time on the interstate you are bound to spot an older Peterbuilt lugging a trailer but it is highly unlikely that you will see one blasting down the road powered by three Pratt & Whitney J34-48 jet engines. These turbojets, rated at 12,000 hp each, formerly powered the Navy’s T-2 Buckeye jet trainers. In aviation parlance, the J34-48 was rated at 3,000 pounds of thrust (4,200 on afterburner).
Converting pounds of thrust to horsepower is pretty tricky but it gets easier when you have a known thrust (12,600) pushing a known weight (6,000 lb. truck) a known distance (say a ¼ mile) in a known time (7.2 seconds). The actual formula is far more complicated
When you have 36,000 horsepower pushing you down a track (or airstrip) there are a few details you have to consider to come out alive at the end of the ride.
- Keeping the truck on the ground. When you are travelling at 300+ mph in anything you are going to need more than just a spoiler to keep the rubber on the road. On Shockwave the three jet engines are canted 30 to put downward pressure on the platform.
- Keeping the tires from flying apart. Shockwave uses standard semi-truck tires however they shave 80 lbs. of rubber off each one to reduce mass and minimize the effect of centrifugal pull.
- Preventing running out of fuel. A typical performance starts with a flame throwing, smoke billowing display to rev up the crowd followed by a 7 second blast down the runway or track. The typical show consumes 180 gallons of diesel. The truck’s saddle tanks carry about 190 gallons. At full throttle the jets gulp 400 gallons a mile (about 100 gallons for ¼ mile), more when the afterburners are in use. Keeping a tight eye on fuel consumption is necessary to keep from flaming out early.
- Staying in the driver’s seat. Driving (or piloting) a jet truck can be a physical challenge. During the ¼ mile your body will be subjected to as much as 6 gs and then in less than 2 seconds, experience negative 9 gs when the drag chutes are deployed. To keep you ensconced in the seat Shockwave uses a complicated 10 point harness that takes the driver and an assistant about 2 minutes to hook up.
- Stopping the beast. While Shockwave is fitted with large diameter disc brakes on each wheel it takes two 16″ aviation parachutes to provide the drag needed to bring the truck to a stop and as we mentioned above those chutes work really, really well.
There’s the Race and then There’s Putting on the Show
Sometimes Shockwave is a solo act but frequently, particularly when it appears at air shows, it will race against an airplane. These events usually involve a low flying prop plane approaching from behind at about 200 mph and Shockwave blasting off from a dead stop to try and beat the aircraft over the next ¼ mile.
That’s exciting but it’s over in a matter of seconds.
What the crowd really loves is the demonstration of fire, smoke and noise before the race begins and that takes some coordination on the pilot’s part.
Inside the cockpit there is an array of throttles and levers that would make Rube Goldberg proud. Three jet throttles, an afterburner throttle to provide the pops and flames, another lever that pumps raw fuel up the exhaust stacks which are equipped with piezoelectric igniters, a master throttle, a thrust lever that redirects the flame from the afterburners so they don’t melt the track (unfortunately this didn’t work in an Ohio show and the track actually caught on fire) and of course a lever to pop the chutes.
Shockwave is a hit and it looks like 2016 is going to be its busiest year ever with 35 events already scheduled across the country. If you have an opportunity, don’t miss this rocking jet truck phenom!