Chris,

I sent you a test message at what I think is your aol address. Thanks for the information.

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What I'm looking for:

I'm upgrading my atmospheric entry heat shield sizing code from three-degree-of-freedom (3-DoF) to six-degree-of-freedom (6-DoF). Please excuse me if what I am about to explain is obvious to you. A 3-DoF code only simulates a spacecraft's velocity vector (three velocity components) as it enters a planet's atmosphere and treats the spacecraft as a point mass. A 6-DoF code simulates the spacecraft's velocity vector AND the spacecraft's orientation, i.e. the three angle's that establish where the spacecraft's body is pointed with respect to the celestial sphere (inertial space). These three angles can be used to determine the spacecraft's angle-of-attack, side-slip and bank angles which in turn define the spacecraft's lift and drag as it flies through the atmosphere. The three orientation angles also establish the location of the heatshield's stagnation point which is where the heatshield gets hottest. We almost always use 3-DoF simulation for heat shield sizing which is unsatisfactory IMHO. A real aeroshell entering an planet's atmosphere is always wiggling around (precessing and nutating if it is spinning). The Viking aeroshell is unique in the history of American spacecraft as the only nonspinning aeroshell to enter a nonterrestrial planet's atmosphere. The aerodynamics of the Viking aeroshell was well characterized by the engineers at Martin Marietta when they designed it. I have most of Martin Marietta's aerodynamic data books for Viking. If I could get the inertial measurement unit's flight data for the Viking-I aeroshell as it entered the Martian atmosphere then I could use that data to validate my 6-DoF simulation code. This is the Holy Grail in terms of spacecraft simulation, i.e. validation against actual flight data. If one can show a program actually reproduces real flight data then all discussion about the program's vailidty ends. I was able to do this in the 3-DoF context when I reproduced flight data from thermcouples embedded in the heat shield of Mars Pathfinder. If I can do the same for 6-DoF against Viking telemetry then my program's utility pops up to another quantum level.

Gary