SpaceX the Alan Notes

From this you can see that at first, the rocket had a fairly constant velocity in the vertical direction with a value around 35.8 m/s (86 mph). That seems quite fast—but what do I know? I’m not actually a rocket scientist. The horizontal velocity seems to be much smaller, but I will let you explore that for a homework question (see below). The other interesting thing is the tilt angle of the rocket. My original intention was to mark the top and bottom of the rocket in order to calculate the tilt angle. However, this didn’t work so well. The top of the rocket is much more difficult to see than the bottom (probably because of the flames and stuff coming out of the bottom). Fortunately, it doesn’t matter where I mark the top of the rocket as long as it is in a line along the length of the rocket. If I have these two points (top and bottom), I can calculate the angle. Here is a diagram showing how that would work.

With that, I can plot the angular position of the rocket as a function of time.

That plot turned out better than I expected. Clearly you want the rocket to end up with a zero degree deflection – but you can see that at the end it was significantly more than 0 degrees.

Homework

This is just too nice of a video to not include homework. So, here is your homework. Some of them are easy and some are not so easy.

• Estimate the vertical acceleration of the rocket. At what time is the acceleration the greatest? How many g’s is that?
• Estimate the mass of the rocket and determine the thrust needed to achieve this acceleration.
• How much fuel would this rocket use to land? Yes, this is a tough question. Really, you need to know the speed of the propellent to determine the rate that fuel is used. I suspect you could look up the type of rocket engine and this would give you a starting point.
• Make a graph of tilt angle as a function of height above the platform. You can do this with plotly. Just go to the