The Human Catapult Project
What Is It?
Enlarge picture Our human catapult system was designed to launch BASE jumpers more than 20' vertically and 50' horizontally over the edge of a bridge during a BASE jump, but it's also been used to hurl "normal" people into lakes and other bodies of water. It utilizes a 120 gallon steel air tank controlled by a 2" ball valve to force air into a Ø10" x 22" pneumatic cylinder. When pressurized, the pneumatic cylinder forces the 12' long truss section to rotate 70° before being dampened with an adjustable air cushion. Our catapult has been thoroughly ground tested by repeatedly launching 150-200 lb. sand bags. Nearly 100 successful human test launches into a lake were performed in the summer of 2012. We're also exploring other methods to softly launch people over dry land. At Bridge Day 2012, our catapult system launched 24 excited BASE jumpers over the 876' tall New River Gorge Bridge. Even the most experienced BASE jumpers with decades of parachuting experience were visibly nervous before being launched over the third tallest bridge in the USA. Subaru is our main sponsor this year.
Can I rent it? Is the design available online?
Further information on our human catapult can be obtained by contacting us. Our catapult is available for rent and it can be shipped anywhere in the USA. It can be used to launch your best friends into a lake, swimming pool, or airbag. If you're a jumper, it can be used to launch parachutists over a bridge, cliff, or building. If you'd like to build your own catapult, our well-documented design (Solidworks CAD files, drawings, part specs, prices, online links, calculations) is available at a reasonable rate.
We've finally finished two videos that documents the construction, testing, and human launches from our catapult system at Bridge Day and Maple Lake. The first video is 19+ minutes, showing more catapult assembly, launches, and dialogue. The second video is condensed into eight minutes. Enjoy.
Long version (19+ minutes)
Short version (8+ minutes)
What Time Will Launches Occur On Bridge Day (October 19, 2013)?
Catapult launches start around 9:30am and should occur every 30 minutes throughout the day. The schedule is subject to change depending on weather and jumper participation.
Who Built It?
Bridge Day BASE Jumping Organizer and mechanical engineer Jason Bell designed and assembled the catapult in late 2011. Tri-State Electric and Machine Co. fabricated the steel framework.
Why Was It Built?
Most BASE jumpers would agree that their ultimate launch platform would be a "trebuchet" or "catapult". Several years ago, Jason envisioned a safe and suitable way of providing this type of device after viewing the video of a smaller catapult used in Switzerland. Having successfully engineered the Bridge Day launch platform in 2004 and the diving board system in 2003, a jumper catapult was the next step in Jason's search to offer something new to the event and challenge his engineering skills. He spent much of his free time in 2011/2012 designing and fabricating the catapult, purchasing the required components, triple-checking engineering calculations, consulting with other engineers on the dynamics of the system, and testing it with considerable success.
Enlarge pictureHowever, a human catapult isn't really a new idea at all. TV shows such as ABC's "Wipeout" have recently used a human catapult. Several foreign companies built their own versions used to launch people into bodies of water. Actually, BASE jumpers have been catapulted off the New River Gorge Bridge in the past. Back in the early 1990's, Jason recalls seeing video of a stuntman being shot over the bridge railing while attempting to grab a cargo net towed by an airplane. The stuntman never did stay on the net, but he had a parachute as a backup. If we remember correctly, his launch system was normally used for Hollywood stunts and consisted of a seat that moved linearly along a fixed rail.
Our jumper catapult was originally designed to launch jumpers over a bridge or cliff during a BASE jump, although we're now focusing on new launch methods that will cater to non-jumpers. Ultimately, it was the engineering challenge itself that drove Jason to design the catapult and he's very excited to be able to share it with Bridge Day jumpers and spectators again this year.
How Did You Start The Design?
The first task was to determine the available space on top of the New River Gorge Bridge. Since we are allocated the space from the bridge railing to the center white dashed line between lanes, we took some measurements and researched the normal width of a traffic lane. We had to keep the catapult under 20' long. We also analyzed videos and photos from other catapults to determine ideal launch angles, arm lengths, and seat positions. Knowing that our catapult would be mobile with a custom air compressor system mounted at one end (for ballast), we formulated that the rotating arm would be approximately 12' long. Assuming the arm that connects to the pneumatic cylinder would be around 2' long, this gave us a 6:1 ratio. For every pound of weight we needed to launch from the seat, we'd have to exert roughly 6x that much force at the pneumatic cylinder. Moment diagrams and further calculations pointed towards the use of a Ø10" pneumatic cylinder that could exert more than 10,000 lbs of force at 130+ psi. Our pneumatic cylinder also had the tough task of accelerating the load through 70° of rotation within one second and then decelerating during the last few degrees of motion. This was no small task to engineer, especially with the very limited amount of history and information available from other similar catapult systems.
Enlarge picture The design was then injected into Solidworks, a 3D computer aided drafting program. Solidworks enables 3D objects to be drawn and dynamically rotated to determine collisions and clearances. Months of fine tuning the design and adding newly acquired parts into the computer were required. BASE jumpers and other engineers were asked to provide input. Once we were satisfied with the final design, fabrication drawings were produced that facilited Tri-State Electric and Machine Co. to cut, machine, and weld all the parts together. In December 2011, we picked up the framework and hauled it back to Bridgeport, West Virginia where it would be assembled, painted, and tested. Additional welding, grinding, and hundreds of hours of assembly would be required before the catapult was first operated in January 2012. By March 2012, we were launching 150-200 lb. sandbags across Jason's front yard. His neighbors, although curious as to what this new contraption was all about, were used to seeing unique people and equipment around his house over the years.
During September and August of 2012, several days of water testing permitted us to launch the first group of people into Maple Lake near Bridgeport, West Virginia. Maple Lake is a small community with homes surrounding a beautiful lake. Jason presented his test plan at a Maple Lake Board of Directors meeting and they agreed to let him test the catapult. As a way of saying thanks, Jason agreed that every person launched into the water would help pick up trash around the lake at the end of the day. The people at Maple Lake were absolutely fantastic to work with. During our two days of water testing at the lake, we performed more than 100 launches with male and female participants, young and old, BASE jumpers and non-jumpers. Jason was able to launch his wife Jennifer, as well has his brother Logan. Jason considers the first day of catapult water testing (August 5, 2012) to be one of the best days of his life as he was able to see his idea come to life. He pulled the ball valve to launch the first human (Joe Caulfield) and was later launched into the water numerous times. After their first launch, some of the adults came out of the water screaming with joy and giggling like small children.
- Weight: 2500 lbs (approximate)
- Framework: Rectangular 2"x4" steel tubing
- Air Compressor: 2-stage, 175 psi max pressure
- Engine: Honda 11 hp, electric start with tachometer
- Air Tank: 120 gallon horizontal, steel
- Pneumatic Piping: Ø2" steel
- Seat: Custom bucket design (to accommodate parachutes), steel construction with 4" foam padding, custom sewn parapak cover
- Pneumatic Cylinder: Ø10 x 22" steel with rear trunion
- Bearings: Custom designed plain bearing with bronze bushings
- Trailer: Bumper pull 8.5'x20' car hauler with custom rails to guide catapult in
- Estimated hours to design: 200
- Estimated hours spent assembling, fabricating, and testing: 300
- Engineering, CAD, Assembly, and Testing: Jason Bell, Jennifer Bell, Chris Garman, and Joe Caulfield
- Owner: Vertical Visions LLC and Jason Bell
- Fabricator: Tri-State Electric and Machine Co. based in Moundsville, WV
Enlarge picture Many people say that safety is their number one concern. With the catapult system, the importance placed on spectator and jumper safety is elevated far beyond normal levels since Bridge Day is a public event with a considerable amount of media attention.
The following safety mechanisms will be implemented at Bridge Day:
- Spectator hard fencing will be placed around the catapult
- Only trained staff members will be permitted around the catapult during launches
- Only the most highly experienced BASE jumpers (prefer 50+ BASE jumps) will be permitted to be launched from the catapult
- All BASE jumpers using the catapult will be required to attend a briefing on Friday, October 18, 2013 in order to become familiar with the equipment and the dynamics of the launch
- Additional test launches over dry land and water were performed throughout the summer of 2012 using up to 250 lbs at maximum air tank pressures in order to triple-check the system
- Components requiring manual intervention (ball valves) in order to operate the catapult will be shielded from spectators.
- The compressed air tank was designed and constructed in accordance with ASME Section VIII Div-I Code for compressed air storage use. It's also "U" stamped and registered with the National Board of Pressure Vessel Inspectors.
- Grade 8 fasteners were used in all high stress areas (bearings, pneumatic cylinder pivot, etc.)
- The motor/compressor pulleys and belt are fully enclosed
- Any and all equipment failures, damage, cracks, unsatisfactory results, or performance issues of the catapult prior to or during Bridge Day will result in immediate cessation of usage
The First Person Launched
Joe Caulfield was the first person launched from this catapult. He volunteered to be launched into a lake in August 2012 and was the first BASE jumper launched over the New River Gorge Bridge at Bridge Day 2012. He also helped with the initial catapult design and testing. My hat goes off to him for his courage and trust in my design.
Register to Jump
24 slots will be available for our jumper catapult at Bridge Day 2013 starting around July 1, 2013.
Images captured during water testing at Maple Lake in Bridgeport, WV on August 4 and September 3, 2012, as well as Bridge Day 2012. Photos by Sandy Weltman, Jason Bell, and the Vertical Visions photo crew.