Sunday, November 20, 2005

Project Orion Hot Rod Revisited, Part 1

In his comments to my previous Project Orion post, norden made me aware of his Deep Space Bombardment blog, which addresses this project in much more detail. His blog provides some calculations on the Orion's ISP and links to other Orion websites. One of these is a sub-forum on the Universe Daily News Board. This board hosts Orion discussions and includes a thread providing a Compendium of Orion Technical Articles. He also mentioned simulating the flight of the Hot-Rod test vehicle.

The Hot-Rod was successfully flown in 1959 at a test facility at Point Loma, CA. It was boosted by a large BP charge followed by five rear-ejected high explosive charges. It was stable, reaching an altitude of 105 meters and recovering via parachute. The vehicle itself is held by the Smithsonian Air and Space Museum. If you want to see a video of the flight, visit the Nuclear Space Multimedia Gallery. I had previously built a stand-off scale flying model of the Hot-Rod, and decided that I'd take a stab at a simulation.

I decided to model the Hot-Rod in Apogee's Rocksim program. I also had to develop a thrust curve for an equivalent motor that would represent a high explosive blast. Right off the bat, using Rocksim would limit me to three charges vs. the 6 that were actually used. These charges included one fixed black powder charge to get the Hot-Rod going and 5 PETN (Pentaerythritol Tetranitrate) charges. I could probably model sets of these blasts in a single motor file, but that seemed to be too much work (at least for now). I thought success would be attaining a simulation that achieved an altitude of somewhere around 50 meters, half of the actual flight.

I have built the Rocksim model, characterized a pulse detonation motor, and run some initial simulations. So far, I seem to be smarter than those PhD physicists who worked on the Hot-Rod, since mine went twice as high with around half the motors. Actually, this just says my model is inaccurate. I'll follow up tomorrow with a graphic of my Hot-Rod, how I approached the simulation, and all the places where I could have, and evidently did, goof up.

Project Orion Hot-Rod Revisited, Part 1
Project Orion Hot-Rod Revisited, Part 2
Project Orion Hot-Rod Revisited, Part 3
Project Orion Hot-Rod Revisited, Part 4