GOLDEN, Colorado -- UP Aerospace has fully analyzed the mishap that led to the failure last September of its SpaceLoft XL suborbital rocket - the inaugural launch from New Mexico's Spaceport America. Corrective actions have been taken, with design changes to the vehicle now incorporated as the firm targets an April return to flight of the rocket.

Lifting off on its September 25 flight from Spaceport America, the SpaceLoft XL -- a 20-foot (6 meters) tall, single-stage solid-fuel rocket -- experienced problems that led to the vehicle corkscrewing in the air, then crashed into desert landscape after 90 seconds of flight.

UP Aerospace, Inc. conducted a two-month anomaly-investigation process that spanned structural mechanics, aerodynamic analyses, on-board flight systems, radar tracking data, optical tracking data, and a comprehensive study of the vehicle after it landed.

Tale of the tail

Full investigation of the mishap both internal to the company and through outside independent expertise has centered on the rocket's fixed in place, three fin tail section, explained Jerry Larson, President of UP Aerospace, Inc., with its primary business office in Highlands Ranch, Colorado.

Larson said that the launch mishap has boiled down to two things: an aerodynamic stability margin in the rocket that was too low, coupled with the vehicle incorrectly designed not to spin fast enough on its ascent.

"We thought we had plenty of margin," Larson said, but the investigation into the rocket's flight, he said, showed a far less stable vehicle than had been predicted pre-launch.

"There were no fins that fell off. The vehicle actually remained structurally intact throughout the entire flight...down to the ground," Larson said. The rocket's less than adequate spin rate, he added, meant that the rocket could not correct for thrust-induced moments typical for a fixed-fin vehicle nosing to higher altitudes and reaching higher speeds.

All these factors coupled as the rocket reached about mach 4 - four times the speed of sound. The rocket's short flight prevented deployment of parachutes.

"Essentially, it's all isolated to the fin section of the vehicle," Larson told SPACE.com.

Design changes

The SpaceLoft XL's return to flight will feature a fourth tail fin and an increased spin rate, Larson said. The four fins are larger in size and shaped differently in response to the mishap findings from the first flight.

"The new design is robust and can handle very large deviations...so we have built in a lot of margin in the new design," Larson explained. From a return to flight hardware status, the next SpaceLoft XL is ready to go, he said, and will carry customer hardware into suborbital space.

Larson said that the next flight will also carry a comprehensive data sensor suite - built by New Mexico State University -- to gather information about the correction actions taken in SpaceLoft XL's return to flight.

The SpaceLoft XL vehicle can launch up to 110 pounds (50 kilograms) of scientific, educational, and entrepreneurial payloads into space, with an altitude capability of up to 140 miles (225 kilometers).

UP Aerospace is working with the Federal Aviation Administration's Office of Commercial Space Transportation to obtain, perhaps by early March, a return to flight go-ahead and approval for flying the vehicle throughout 2007, Larson said. In addition, UP Aerospace is working on a multi-year lease agreement with New Mexico Spaceport America officials.

Regarding last year's mishap at Spaceport America outside Las Cruces, New Mexico, Larson remained upbeat: "It is part of the business and goes with the territory. We're in it for the long haul. It's a tough business. You can't get into the launch vehicle business with rose colored glasses."