CXV - Crew Transfer Vehicle

The CXV is a concept developed by t/Space for the transport of humans to LEO and the International Space Station (ISS). The concept uses many clever technologies, including air launching, VaPak pressurized propulsion systems, and an aerodynamically stable reentry shape that requires no active control. My involvement with this project was as the test engineer responsible for data acquisition and analysis for the CXV drop testing of the parachute system. The full-size Drop Test Article (DTA) successfully tested the parachute stability and water-entry physics of the actual CXV. It was dropped into the Pacific Ocean on August 3, 2005. The CXV DTA is still on display in Crescent City California to this date!

Background

Transformational Space Corporation (t/Space) developed the CXV as part of their contract under NASA's renewed exploration initiative (Project Constellation). The CXV is part of a fleet of vehicles, which would include modular Crew Exploration Vehicles (CEV), and also the International Space Station (ISS) as part of the system architecture.

The CXV is the crew component that would be used to transfer humans from Earth to Low Earth Orbit (LEO). In LEO, people would either transfer to an existing destination (ISS), or rendesvouz with mission specific Crew Exploration Vehicles (CEV) for missions to the Moon and beyond. A single exploration mission to the Lunar surface would involve a fleet of multiple CEVs, improving overall system reliability and enabling safety critical abort scenarios. If one CEV were damaged beyond repair, the crew of the damaged CEV can transfer to another CEV in the fleet. The resulting scenario would be reduced in scope, but the mission would not have to be aborted and most importantly no human life would be lost (unless part of the original mishap). This approach of using multiple individual vessels for a single mission (instead of a single vehicle) was inspired by the historic success of martitime exploration fleets.

The CXV is carried to orbit on an air-launched booster. The booster is deployed on a large custom-build carrier aircraft. The carrier aircraft drops the CXV and booster combination at approximately 30 to 40,000 ft, which enables many possible abort and recovery scenarios for the crew in the case of a booster failure. The CXV itself is also the reentry capsule for the crew's eventual return to Earth. The shape of the CXV is aerodynamically self-stabilizing and requires no active control during reentry, making the system very reliable and safe.

The embedded video on the right is available in low-res (10 MB) and high-res (100 MB). It is a nrrated animation of the complete CXV concept published by t/Space.

Parachute Drop Testing

The full-size Drop Test Article for the CXV Parachute Landing test was constructed in Mojave, CA, with a water tank for ballast. The tank was positioned so that it created the same offset center of gravity that an actual CXV will have; an offset center of gravity results in the CXV capsule generating some lift during entry, which limits the rate of deceleration and thus the "g" forces that will be felt by the crew. The first photo shows myself and a co-worker applying logos to the DTA in the evening just prior to the test.

The second photo is of a fishing boat which we used as a telemetry receiving station, and also a chase boat to retrieve the parachutes after the DTA splash-down. The telemetry receiving antenna is being installed by the boats captain (climbing on top of the rigging), while I'm running the RF cabling to the cabin to check the receiving station (my laptop). With the availability of cheap electronics, it's amazing how little money can get the job done!

The very sophisticated receiving station is shown in the third photo. The gray box of water-sealed electronics contains a very simple RF to RS-232 receiver, which is then conected to my laptop via USB. In this fashion we were able to monitor real-time telemetry and record data for later analysis. The Drop Test Article was equipped with GPS sensors, inertial measurement accelerometers, and a number of cameras. The camera data was stored on the DTA and not forwarded via RF. The data was later retrieved together with the DTA following splash down. The drop test was conducted in Crescent City, CA and during the entire week leading up to the test the weather was overcast, damp, and rain kept pouring down. It was not until the actual day the test was scheduled that fortune (and the sun!) was smiling on us and we had crystal clear blue skies. It was still windy with fairly rough seas at the drop site, but nothing that impeded the test itself aside from the occasional bout of seas sickness among the crew.

During our lead up time of assembling the pieces of the test article on site, testing the telemetry system with the chase boat and our various coordination activities with local authorities, the local populace became very intrigued with what was going on. There was next to no cell-phone reception at the site, so all of the crew carried two way radios to stay in touch. With Crescent City being a fairly small town and it being off-season for tourism, rumors spread quickly of strange-man-with-radios being sited at restaurants, hardware stores, and the harbor. We had cordoned off a large parking area close to the water front for the assembly of the DTA, and for several days I was driving along the coast to test radio reception for the telemetry system. In the fourth photo I am talking to a reporter from a local newspaper, explaining what we are planning to do on the day of testing. We drew a significant crowd once the helicopters arrived on site to lift the DTA and carry it out to the drop site (a video is available here - 2MB).

Once the chase boat had made it to the drop site, it was time to get serious. The photo shows me in the cabin monitoring the telemetry stream. It was rough seas, so life-vests were mandatory and of course no engineering project can be implemented without the use of duct tape! Staring at the small numbers on my screen while the boat was randomly rolling in the outside swells (the engine was off) gave me my first (and only) ever experience with motion sickness ... causing me to chuck my breakfast over the railing, and head right back to the job. The show must go on!

The next photo shows the parachute retrieval crew. The parachute system was designed and operated for us by Irvine Aerospace. After the splash down, a two-man diving team went out to the DTA to remove the parachute assembly and drag it back to the boat, where it was lifted from the water for a post-test inspection. The same team then returned to the DTA to hook it back up to the large helicopter that had originally dropped it, so it could be retrieved and returned to the staging area. There we removed all the electronics and data recorders, and then donated the CXV DTA to the city of Crescent City, where it is still on display today.

The last photo shows the CXV Drop Test Article (DTA) descending under the parachutes just prior to splash down. The drop test was conducted to evaluate the CXV descent and recovery system and gather data for design refinement. The test vehicle had representative mass, center of gravity location, and the shape of a crew transfer vehicle. Attached to the vehicle were three 85.6ft Do Ringsail canopies, which provided for the deceleration and terminal descent of the CXV. In the test, the vehicle was suspended and released at an altitude of approximately 9340ft. A static line was used to deploy the three canopies, each equipped with two stages of reefing. The parachutes were successfully extracted and the two stages of reefing were demonstrated. However, because of the relatively low dynamic pressure as compared to an actual re-entry trajectory, one of the three parachutes failed to fully inflate. The lack of inflation performance was due to the low dynamic pressure and associated limited positive inflation profile required to completely remove the sacrifice panel.