# Moment of inertia data for rocket stage?

I'm modeling a rocket launch and would like to compare my calculated moments of inertia to actual real-world data from other rockets.

Any rocket would do, though those similar in size to Falcon 9 would be best. Not looking to match numbers precisely---just trying to build some intuition so I can tell if at least my orders of magnitude are right.

Maybe Saturn V, since so much about it is public these days?

Thanks if you have a good reference for rocket mass properties and can point me to it!

• potentially helpful; Reddit: Leg-Based Stability and Moments of Inertia, Scott Manley tweet, and (not a duplicate) here: Moment of Inertia of rocket
– uhoh
Commented May 6, 2021 at 22:23
• If you look at dry vs total weights you can see that most stages are mostly propellant. You can get a pretty good estimate by choosing a temperature and therefore density for each propellant, then imagining cylinders of them with about 95% of the radius of the rocket for the moment of inertia about the long axis. For the short axes you have to be careful as soon as the fuel starts being used, you have partially-filled tanks of propellant and oxidizer at one end of the tanks during flight, and in unpredictable positions during free-fall.
– uhoh
Commented May 7, 2021 at 0:27
• I can't comment but I found this online. history.nasa.gov/SP-4029/Apollo_18-20_Ascent_Data.htm Is this what you mean or are you looking for raw unmodified data? Commented May 12, 2021 at 16:10
• Not quite but hey that’s interesting data! Thanks for sharing. I’m looking for mass, center of mass, products of inertia, and moments of inertia. Either raw or filtered/processed data is fine, so long as it’s from actual measurements and not just someone’s calculated estimates (which I already have). I’m trying to check if my estimates are close to the real numbers. Mostly looking for moments of inertia, but the other parameters would be nice too.
– user39728
Commented May 12, 2021 at 18:18
• Thank you thank you to the person who put the generous bounty on the question :)
– user39728
Commented May 12, 2021 at 20:15

The document S-4B-503N Stage Flight Test Plan contains old-school tabular printouts of output from a simulation of a Saturn V launch. It looks like this (I highlighted the moments of inertia at this time tick).

Here are a few values.

Units
T (seconds)
Mass (lbm)
Moments of Inertia (slug-ft^2)

T= 0
Mass = 6132673.8
Ixx = 2945907.90
Iyy = 658006930.00
Izz = 658006930.00

T=10
Mass = 5840809.9
Ixx = 2945672.00
Iyy = 649995760.00
Izz = 649995760.00

T=151.0400
Mass = 1810461.9
Ixx = 2935195.40
Iyy = 325093860.00
Izz = 325093860.00


Here are some shuttle numbers (also from a simulation)

This snapshot is on the pad, T-4 minutes.

This is Orbiter-only, late in the mission

(personal notes)

• Oh my god, you must be magical, this looks exactly like what I was hoping to find. Thank you thank you :) :)
– user39728
Commented May 13, 2021 at 14:50