On a sunny summer's day, 500 rocketeers converge in a huge, flat field in Alberta, Canada. Most of them are men--some sporting T-shirts declaring things like "I really am a rocket scientist," or "I love the smell of ammonium perchlorate." They have come to launch rockets at the 23rd annual Large Dangerous Rocket Ship (LDRS 23). One of them is Mayo Clinic scientist and physician Andrew Limper, M.D. Dr. Limper is qualified to fly Level 3 rockets--the most powerful high power rockets in sport rocketry.

Andrew Limper, M.D. prepares to launch "High Anxiety" - his 11 foot, 60 pound, high power rocket.
Photo by Nadine Kinney

While some paint their rockets in elaborate designs, build copies of military missiles or install digital camcorders on board, Dr. Limper gets his kicks from dabbling in the physics of flight.

"I enjoy the challenge of designing and building a rocket to fly to a predetermined altitude at a predetermined speed and seeing how close I can get it to perform as programmed," says Dr. Limper.

High power rockets are the big brothers of the kits you put together in the basement when you were a kid. Rockets are classified according to motor power by letters of the alphabet. Each letter represents twice the power range of the previous letter. Model rocket motors range in power from the diminutive "A" to the mighty "G." Yet they are like toy hammers to pneumatic drills when compared to the "H" to "O" high power rocket motors. These muscular monsters are further subdivided into three levels and can only be mail-ordered by adults who have passed rigorous tests.

Dr. Limper built model rockets in high school and reignited his passion after watching a nighttime shuttle launch ten years ago. Despite the name of his biggest rocket, "High Anxiety," Dr. Limper swears his hobby makes him relax.

"It's a great diversion from my work," he says. "In fact, if I come home stressed out, my wife informs me I'll be flying rockets on the weekend."

Dr. Limper has designed and built six large rockets and dozens of smaller ones and is experimenting with developing a new type of rocket fuel. He constructs his rockets from plastic and fiberglass, often reusing parts from retired models. While the motors are single-use, the body can be flown many times. Recovery devices are compulsory and usually consist of a main and a smaller drogue parachute.

Dr. Limper enjoys the camaraderie of club meets and large events.

"High Anxiety" lifts off on its way to reaching a 5,500 feet altitude.
Photo by Nadine Kinney

"It's not competitive--total strangers help each other as ground crew or by lending equipment," says Dr. Limper. "Everyone just wants to see a successful flight, although the unsuccessful ones can be pretty spectacular too."

The pyrotechnics of igniting fuel in a contained space would seem to make rocketry a dangerous occupation. Yet the sport's safety record is outstanding--there has never been a fatality.

"Being a physician, I get called on whenever someone is injured," says Dr. Limper. "All I've ever seen is cuts from tools, a few burned fingers and a dislocated shoulder. The FAA (Federal Aviation Administration) and BATF (Bureau of Alcohol, Tobacco and Firearms) impose stringent regulations that keep the sport safe. We only launch the monsters in pretty remote places."

The success rate of high power rocket flights is limited and Dr. Limper has had his share of disappointments. He hasn't forgotten a two-mile hike through searing heat in the Mohave Desert with a 20 pound rocket on his back. The rocket had drifted off course with an unexpected wind.

At the recent LDRS 23 event, Dr. Limper launched eight rockets successfully, one reaching 7,300 feet. His disappointment came on the one day that it rained--the only day when experimental flights were permitted. That meant his 12 pound, nine-foot rocket, "BBXtreme," which he had rushed to finish, then crated and shipped to Canada, would not fly.

"I was looking forward to watching "BBXtreme" fly to10,000 feet and hitting Mach 1.4," he laments. "It will be six to nine months before I get another chance to launch this one."

While Dr. Limper must cool his jets when it comes to "BBXtreme," as chair of the Division of Pulmonary and Critical Care Medicine, and director of the Thoracic Diseases Research Unit and of his own lab, you can rest assured he will soon be back in his basement sanding away on his beloved stress relievers.