Just a quick update about the tool I alluded to in the previous post. A couple of weeks ago I started writing a program, currently referred to as “DragFinder”. It takes the weight of a vehicle (a rocket, usually), a RASP file containing the thrust curve for the motor (such as you might find on ThrustCurve.org), and some flight data (currently altitude vs time). The program then estimates the drag force vs time for that flight.
Next on the list is converting the drag force vs time over to drag coefficient (Cd) vs mach number, which shouldn’t be too bad. I believe that should take both altitude and speed into account, hopefully resulting in a fairly accurate drag estimate.
So how do I verify that my code is working? Here’s where I’d like some help from rocket hobbyists out there, if anybody reads this: I need data. I need information about rockets including their weight, motor used, frontal area or diameter, and flight data (either altitude vs time or acceleration vs time). I’d like data for big rockets, small rockets, high-altitude and low-altitude rockets, everything I can get. I can get data from a few rockets of my own, but the more the better. Real data will allow me to validate that the software works (and find out why, if it doesn’t). I can then be confident that DragFinder will be an effective tool for characterizing the drag on my ramjet project. And, of course, I plan to post DragFinder for free so that anyone else that wants to can benefit from it. Anybody?
