Young: S-IC Ignition.

Duke: Wow

Young: Wow is right. There goes a train that is leaving. Lift-off - you can tell lift-off because everything is moving.

Duke: It is like an elevator slowly lifting off. But, at ignition, I had the lateral frequency of something or other. It just kept shaking at the same frequency throughout the whole S-IC burn. You felt yourself going faster and faster and faster. I had the feeling it was a runaway freight train on a crooked track, swaying from side to side. That was all the way through the first stage.

Mattingly: Are you saying that the frequency changed?

Duke: No, the frequency stayed the same. But, my impression was the 'g's made it feel like we were going faster and faster and faster.

Young: My impression was unlike a fixed-base simulator, you sensed the yaw, roll, and pitch programs; but, the rate changes are negligible.

Duke: I didnÂ’t sense any of that.

Mattingly: I didnÂ’t sense lift-off except for the lights. I didnÂ’t sense the program. To me, it was just like fixed-base simulator with the vibration on top of it.

Duke: I felt the slow acceleration.

Young: Some guys sense lift-off and some guys donÂ’t. Cabin pressure - Did you notice that relieving on time?

Duke: Yes, I heard it, as a matter of fact. [See 000 00 57.]

Mattingly: I thought the simulation of that was very realistic.

Young: It really was. Dynamic pressure noise builds right up to max Q. That thing is making some kind of racket. Engine gimbal and retro motion - I didnÂ’t notice it. S-IC inboard and outboard ECO - At inboard cut-off, we got this minor damped unloadings and when the outboard engines cut-off, we got at least four times as much.

Mattingly: I was well braced for it. IÂ’m sure glad I was. That really gets your attention!

Young: I mean to tell you it does. I was holding on to the bottom of the T-handle, at that point, because I sure didnÂ’t want to do the wrong thing.

Duke: ItÂ’s a good idea to brace yourself. And, I was surprised with the debris that I caught out of my left eye as it came by the hatch window from the staging.

Young: Hey, thatÂ’s another thing that you remarked on.

Mattingly: Yes. That amazing.

Young: The debris was going right along with us.

Mattingly: It was passing us. I donÂ’t understand that.

Duke: I think that was from retrofire.

Mattingly: No, sir. This was during the powered flight steady state. There were particles; I looked out JohnÂ’s window and particles were going past us in the same direction. I kept looking at that; thereÂ’s no way. But, it did it. I donÂ’t remember it on the S-I; but, I remember it on the S-II and the S-IV.

Slayton: This wasnÂ’t during the staging sequence?

Mattingly: No, sir. This was steady state, powered flight well after staging; and, I donÂ’t know where they caine from. I donÂ’t know what they were, but they were there.

Young: S-II ignition was nominal. I got a feeling it took a little longer to get those lights out.

Duke: I did, too.

Young: For some reason we noticed the PU shift on the S-II, which was at a different time than nominal. Maybe three or four seconds early. I donÂ’t remember just when. It may be in the onboard tape.

Mattingly: I think itÂ’s on the tape because we commented on it. But, it was several seconds early.

Young: Different. The Launch Escape Tower and Booster Protective Cover Jettison. That was on time and you can see the whole works go off. I didnÂ’t see it on Apollo 10, but I sure saw it this time.

Duke: It was great. Every pyro event was just beautiful. You could hear it, feel it, and see it.

Young: S-II engine cut-off was on time and nominal.

Duke: I thought the S-II was very smooth and very quiet. I had the sensation of very low acceleration or 'g's and no noise at all that I could tell. I felt like we were almost floating at that time.

Young: Well, it was low 'g's. S-II/S-IVB separation was nominal. The S-IVB ignition was nominal. Communications - We didnÂ’t have a bit of problem with communications throughout the flight. Controls and displays told us just what we wanted to know. Crew comfort was okay.

Duke: On control and displays, I might add a comment here that pre-lift-off, when we did that gimbal motor check, it was more apparent on the fuel cells than the battery buses. But, in flight, it was more apparent on the battery buses than in the fuel cells. When you started them at six minutes. I donÂ’t know why that is.

Young: The reason is we were not on full internal power during the ground checks.

Duke: ThatÂ’s probably the reason.

Mattingly: Oh, we were on full internal power.

Young: I thought we were.

Mattingly: Sure we were. Once you bring the fuel cells up, we do not have any external power coming in. IÂ’m sure that by the time we climbed in, we were running on fuel cells.

Young: Maybe so.

Mattingly: Maybe itÂ’s typical. Maybe gravity has something to do with the responses.

Young: ItÂ’s no big deal.

Duke: Crew comfort through powered flight. Good.

Young: Man, I tell you, you just hope that mother keeps running because there isnÂ’t a lot you can do if it quits. Pogo comments - We noticed a buzz on the S-II.

Mattingly: S-II and S-IVB both.

Young: And it stopped at 9:07, I remember that; 9:05 to 9:07, it stopped. I donÂ’t remember where it started. I thought it pulsed up and then died out and then pulsed up and died out. It had an amplitude variation that would go up like that and then come back off and then go up and come back off. I couldnÂ’t tell you what frequency it was, but I imagine it was well in excess of 40 cycles per second.

Mattingly: I think the tape will say what time it started.

Young: Yes. I bet the accelerometers in the CSM picked that up also.

Mattingly: That might be.

Duke: That was probably too high a frequency for the BMAGS.

Slayton: Was it the same frequency on both boosters?

Duke: Yes.

Young: So, it could be an air-stage problem or it could be something coming through the SLA.

Duke: But I wasnÂ’t concerned about it, were you?

Young: Yes, but thereÂ’s nothing you can do about it. I mean, if it is going to damp or not, thereÂ’s nothing you can do.

Duke: I never had the feeling it was divergent. It was just a constant buzz.

Mattingly: On TLI, it seemed to be increasing in amplitude; although I thought the frequency was still the same.

Young: Yes. ThatÂ’s what I thought all the way to ECO. But, there was a buzz on the S-IVB all the way to engine cut-off. And, it was a high frequency buzz.