Spacelog Apollo 13

Okay. DELTA-V_Z in NOUN 81 is minus 02226.

Okay. Good readback.

Somehow that didn't add up with the DELTA-V_X to give a DELTA-V_R of that magnitude. It seems like it'd been bigger.

Okay, Houston. I'm not having too much luck holding this particular attitude.

Okay, Jim. Stand by 1.

Okay, Aquarius. When you get her pretty much in attitude there, and it looks like you're as close as we need to be, we'd like to try a control mode and see if it will work; sort of a semi-PTC. We'll leave the ball powered up for this, and if this doesn't work, why, we'll have to revert to ATTITUDE HOLD mode. But—Stand by 1, please.

We'd like you to think about this control mode, Jim, and see if you think it might work from what you know right now. We're a little skeptical, but we'd like to put it to you. So, once you get in a pretty good attitude, monitor in VERB 16 NOUN 20, go to PGNS MINIMUM IMPULSE, VERB 76, as we have, and set up a yaw rate—yaw rate to the right. Monitor the middle gimbal on R₃ on the DSKY and see if she'll kind of stabilize out. If not, the only other suggestion we've got is to go to PGNS ATTITUDE HOLD. We'll keep the ball up until you make this evaluation.

Okay, Houston. You cut out, say again.

Okay. Where'd you lose me, Jim?

I lost you when you said try the control mode; you're a little skeptical.

Okay. From what you say, we have to be a little skeptical of this procedure, but we'd like to have you try it and have you evaluate it. You can monitor the middle gimbal on R₃. Before we power down the ball, we want your evaluation. The next best choice is PGNS ATTITUDE HOLD. Over.

Okay. I'll try it.

Okay. Go ahead with the control mode procedure.

Hello, Houston; Aquarius.

Go ahead, Aquarius.

Okay. I'm not … you. I can monitor register 3. I can probably keep it out of …—going into gimbal lock.

Roger. How are pitch and roll?

Okay. I think I can control the gimbal angles in 16 20 with the compressors the way they are, but I'll have to try MINIMUM IMPULSE—just a minute.

Okay. Copy. Leave them in.

Okay, Houston. I can control yaw in minimum impulse, but stand by on pitch.

And, Fred-o, the DELTA-V_R resultant computes with the components.

Fred's off the COMM now, Jack.

Roger. Your PAD is good.

And, Jack, we didn't get that whole sentence there.

Okay. I said that the DELTA-V_R that Fred questioned computes well with the component—its rms.

Okay. Copy.

Okay, now. Jack, let's go over this once more. You wanted me to try out control of the spacecraft in the PULSE mode. Is that correct?

That's affirmative. Set up a yaw rate and monitor the middle gimbal angle.

Okay. I can do that. I'm not too sure whether I can control roll or pitch in pulse, but I can control yaw in pulse—yaw in pulse on the ball.

Roger. And remember we're not going to have a ball there, so that we're going to be monitoring CDUs on the DSKY, and if we get it off, it will be pretty hard to figure out where to fly back to; and, well, in addition, have to control the OMNIs while we're doing this.

Roger.

Without the ball, I still have use of the TTCA for control of the—angles.

Affirmative. You'll have the TTCA for pitch and roll.

Okay. I think I can do that without the ball, and if you just give me the TTCAs I think I can control the spacecraft using 16 20.

I'm going to yaw right.

Okay, Jack. I am now—The REGISTER 1 is in the DECREASE mode.

And, Houston, do you see anything wrong with this spacecraft motion?

We have a data drop on right now, Jim; we'll look at it as soon as it comes up.

Okay, Aquarius. We're going to dispense with this control mode. We'd like you to fly the machine back to the original attitude that you had, and we'll go PGNS ATTITUDE HOLD, and then we've got to get that ball off the line to save some power. And then, in order to keep even heating, every 15 or 30 minutes, we'll give you a call to give us 90 or 180 degrees of roll—of yaw.

Okay, Houston; Aquarius. I'm flying it back over towards the initial angles you gave me of a pitch of 257. I'll get near the bellyband in roll and yaw; then I'll go to PGNS ATT HOLD.

That's affirmative, Jim. And then we're going to have you go through a powerdown procedure.

Okay.

And you'll need VERB 77 with ATT HOLD when you get there.