Armadillo Aerospace rocketeers moved a step closer in their effort to win the $10 million X Prize, the competition that calls for building a reusable, passenger-carrying suborbital spacecraft.
On July 5, the Mesquite, Texas-based group carried out a milestone helicopter drop test of hardware essential to the team's X Prize candidate design.
John Carmack, head of Armadillo Aerospace, gave a thumbs-up regarding the success of the recent drop test. "Overall, the operation was a good success, and demonstrates that recovering the complete vehicle after flight should work fine," he later reported.
A leading do-it-yourselfer in the rocket business, Carmack is perhaps better known as a founder of id software, a computer gaming company. He is also the brain behind such PC action games as Doom and Quake and is personally bankrolling his space company.
Armadillo Aerospace is a small research and development team working on computer-controlled hydrogen peroxide rocket vehicles, with an eye towards X Prize-class vehicle development.
The X Prize is a $10 million cash purse that will be awarded to the first team that successfully launches three people to an altitude of 62.5 miles (100 kilometers) returns them safely to Earth and then repeats that feat with the same vehicle within two weeks.
Sandbags for passengers
For the July 5 test, the rocketeers welded in strapping points within the vehicle to hold 600-pounds (273-kilograms) of "passenger" sandbags in the cabin area. Also a set of five Olympic barbell plates were mounted on a peg at the vehicle's end to simulate the weight of the final engines, plumbing, and backup recovery system that will be on the group's full size vehicle.
A Texas-state helicopter towed the vehicle to altitude over open landing area, then released the craft.
"We all held our breath as it started to fall, but the drogue immediately inflated and started pulling the main canopy out. It was nine seconds from release to full canopy inflation. The opening shock was negligible, barely hitting 2G’s (twice that of Earth's gravity)," Carmack said. For high altitude flights, Armadillo engineers are aiming for a 200-mile-per-hour terminal velocity under the stabilizer drogue at the time of main canopy deployment. "So opening shock will be much greater then," he added.
On close examination after touchdown, the vehicle's crushable nose cone had buckled right at the mounting point from the angled impact. Overall, the vehicle looked basically sound, Carmack reported. None of the sandbags in the cabin ruptured.
Lessons learned
Once back at Armadillo Aerospace facilities, the vehicle was completely inspected.
"We are probably going to continue using this cabin for the first couple flights of the big vehicle, but start on a second-generation cabin structure that will incorporate some improvements for off-angle landings, as well as several other lessons we have learned in working with the current cabin, Carmack reported.
Accelerometer data showed 10 G (10 times Earth's gravity) acceleration peaks during the parachute landing and bounce. That is over twice what the group saw in earlier, straight down drop tests. "This is still acceptable, although bouncing up and back down in the cabin would have been a pretty harsh ride," Carmack said.
Some changes to the vehicle structure will improve the behavior of the crush cone and tipping over effects. Parachute canopy changes are being considered to reduce oscillations of the craft seen during the descent, Armadillo Aerospace officials reported.
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