# How can I estimate the Coefficient of Drag on a Saturn V rocket, a simulator or some data would be pretty awesome

I'm trying to get some information on this and its proving difficult as the information is usually acquired experimentally from what I've found. A single number at a specific altitude and speed would be more than enough.

Bob Braeunig's Saturn V simulation page (gone missing; archive.org link) has good information on how he estimated the drag coefficient, and a convenient CD vs Mach number plot. The key point:

No information has been found regarding the drag coefficient of the Saturn V, however at least one data point can be calculated – that at the time of maximum dynamic pressure. The Saturn V News Reference, August 1967, states "At approximately 69 seconds into the flight the vehicle experiences a condition of maximum dynamic pressure. At this time, the restraining drag force is approximately equal to 460,000 pounds." From Ascent Data we see that, for Apollo 11, maximum dynamic pressure (also called maximum q) occured at a time of 83.0 s, an altitude of 44,512 feet, and had a value of 735.17 lb/ft2. There are two methods we can use to estimate the drag coefficient at maximum q.

First, given that q = rv2/2, we substitue q for rv2/2 in the drag force equation, obtaining FD = q CD A. We now rearrange the equation, plug in our known values (assuming 460,000 lbf is applicable to Apollo 11), and solve for CD.

CD = 460,000 / (735.17 × 1,216) = 0.515

The CD versus mach number plot is based off data from the Atlas rocket, so its applicability to Saturn V is questionable, but here it is:

• Added an archive.org link for posterity. Sep 16 '18 at 2:55
• Excellent, thanks! I've included it here.
– uhoh
Sep 16 '18 at 3:07