Apollo Entry

From Apollo mission reports here

Apollo 7 and 9 were earth orbit, slower reentry. Apollo 8 and 10 through 17 were lunar missions with high speed reentry of the command module. Apollo 11,12, and 14-17 were landing missions.

Useful graphs for Apollo 8, 10, and 11. I cannot find useful entry information after Apollo 11, so these three sets are hopefully representative of the other six lunar missions.

The command module had roll and attitude thrusters, which were used to indirectly control the trajectory. The center-of-mass of the command module was offset toward's the astronaut's feet. That edge of the CM would lead into the airstream; the capsule could be rotated with the roll thrusters so that the lift vector (directed towards the nose) vectored the spacecraft left, right, up, or down. The lift-to-drag ratio for the CM was approximately 0.3, so if the entry drag was near maximum at 6 gees, the lift vector would be about 2 gees, pointed whichever way was necessary to adjust the trajectory. Coming in above orbital velocity, the lift vector would be pointed earthward to keep the CM at the right altitude; below "Vcirc" the lift vector was pointed up to maintain altitude (and thus density and drag force).

The "entry scroll" is a paper graph that was preloaded into the Entry Monitoring System, and scrolled past a little window in the control panel between the left and center seats. If the computer failed, the command module pilot adjusted the roll and lift of the command module to follow the graph. There were two graphs, skip and no skip; if weather over the primary recovery site was bad, the computer (or the CMP manually) would select the "skip" graph and extend reentry by a few hundred kilometers. Apollo 11 skipped to avoid a thunderstorm, the other missions did not skip, and landed at the primary recovery site.

Except ... it looks like Apollo 16 DID do a skip, see below:

Click pictures for enlargements


Apollo 8

Entry Monitor System Scroll, Gees vs Velocity

attachment:a8a.png attachment:a8b.png

Roll vs Mission Elapsed Time

attachment:a8r.png


Apollo 10

Entry Monitor System Scroll, Gees vs velocity

attachment:a10ems.png

Roll and Altitude vs Ground Elapsed Time

attachment:a10roll.png attachment:a10alt.png

Gees and Lift/Drag vs Ground Elapsed Time

attachment:a10gee.png attachment:a10LD.png

Range and Vertical Velocity vs Ground Elapsed Time

attachment:a10range.png attachment:a10rdot.png


Apollo 11

Table III

EI time

Load g

V f/s

range n mi

° Bank

Rdot f/s

0:00

0.000

36190

1593

0:28

0.049

36276

1418

0:30

36277

0.0

-3186

1:18

-666

1:30

30176

54.43

211

1:56

1.057

22091

-86.68

Entry Monitor System Scroll, Gees vs Velocity

attachment:a11ems.png

Roll and Altitude vs Time from Entry Interface

attachment:a11roll.png attachment:a11alt.png

Gees vs Time from Entry Interface and Lift/Drag vs Mach Number (velocity)

attachment:a11gee.png attachment:a11LD.png

Range and Vertical Velocity vs Time from Entry Interface

attachment:a11range.png attachment:a11RDOT.png

Velocity vs Time from Entry Interface

attachment:a11vel.png


Apollo 12


Apollo 13 Mission report page 9-17, two brief paragraphs about entry and landing (useless)

Apollo 14 Mission report page 5-28, two brief paragraphs about entry and landing (useless)

Apollo 15 Mission report page 114, two brief paragraphs about entry and landing (useless)

Apollo 16 Mission report page 9-56, "entry deceleration exceeded 7 gees" (semi-useless)

Apollo 16 was the highest gee reentry.I wonder why??? According to the flight journal,

PAO = Public Affairs Officer:


Apollo 17 Mission report page 190, no trajectory data (useless)

ApolloEntry (last edited 2017-01-02 08:30:20 by KeithLofstrom)