Consider the Falcon 9.

In emergencies, the launch escape system will fire to separate and propel the crew module away from the rocket.

After the engine shuts down, the payload trunk will separate leaving the crew module to carry on alone.

The crew module, being aerodynamically unstable by design, will quickly flip over so that its heat shield is facing forward.

And this means a big change in the drag coefficient of the crew module.

Before the flipover, the streamlined ogive-like nose will aim into the wind, giving a fairly low drag coefficient. After the flipover, the blunt heat shield will aim into the wind, giving a fairly high drag coefficient.

I know there is no data out there for the drag coefficient, but if it is/were close to other ogive-like vehicles, then roughly what values would you expect? Would 0.3 for nose-forward and 1.5 for heatshield-forward be in the ballpark of reasonable?

I’m ignoring dependencies on speed and altitude at my peril. Just trying to get a baseline expectation for the change on the drag coefficient due to the flipover alone.

Even better, is there data out there for a flipover of an pointy vehicle with a blunt heat shield?

Rough and approximate are fine for my purposes. Think “ballpark” if you don’t have exact numbers.


  • 2
    $\begingroup$ This is a gold mine of aero coefficients for the Apollo CM ntrs.nasa.gov/api/citations/19680021973/downloads/… $\endgroup$ Commented May 27, 2021 at 0:16
  • $\begingroup$ Thank you! This will keep me occupied for a hwile :D $\endgroup$
    – user39728
    Commented May 27, 2021 at 1:24
  • $\begingroup$ OK, just at a glance, this is gold. Is there something like this for the space shuttle or Saturn V (including the rocket stages)? Thanks again! $\endgroup$
    – user39728
    Commented May 27, 2021 at 1:27
  • $\begingroup$ If you write your comment as an answer, I'll accept. This is miles better than anything I'd hoped to find. $\endgroup$
    – user39728
    Commented May 27, 2021 at 1:32
  • $\begingroup$ OK, thanks, will do. I've seen some shuttle data but iirc it's all in axial form so not too user friendly. I would imagine there's Saturn launch vehicle data on ntrs somewhere. $\endgroup$ Commented May 27, 2021 at 1:59

1 Answer 1


NASA Technical Note TN D-4688 AERODYNAMIC STABILITY CHARACTERISTICS OF THE APOLLO COMMAND MODULE contains a wealth of aerodynamic coefficient data for the baseline and various proposed modifications of the Apollo command module.

Here's one example of CD for various angles of attack and Mach numbers.

enter image description here

  • 1
    $\begingroup$ This is just an epic trove of data. $\endgroup$
    – user39728
    Commented May 27, 2021 at 2:13

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