16

For shuttle it was commanded by the vehicle computers. At T-31 seconds control of most remaining countdown events was handed over to the vehicle, including SRB ignition and blowing the hold-down post nuts. Source: Countdown See What holds the Space Shuttle orbiter itself stable on the launch pad? for details of the mechanism itself


14

For Apollo, the signal came from a small computer room built inside the mobile launch platform. Giant holddown arms, whose name exactly describes their function, are positioned on the launcher surface to support and restrain the Saturn V. These arms hold the rocket during the first 8.9 seconds of ignition of its mighty engines while the computer beneath, ...


9

In August 1990, there were three shuttle stacks at least partially assembled on their MLPs at the same time: Columbia for STS-35, Atlantis for STS-38 and Discovery for STS-41. The picture in this forum thread on NasaSpaceflight shows Columbia and Atlantis, as Discovery was in the VAB at the time.


5

The center of mass of the Saturn V at liftoff is somewhat lower than you might expect -- 27 meters up, about a quarter of the way up the stack. This is because the upper stages are largely filled with liquid hydrogen, which is much less dense than the fuel and oxidizer in the first stage. Thus the yaw moves the upper end of the rocket much further than the ...


4

Saturn V vented GOX directly to the atmosphere during countdown. Watch any Apollo countdown video such as Apollo 11. The Apollo 12 SA507 reference manual mentions propellant venting on pages 4-12 (S-IC "Prior to launch, boil off in the lox tank may be harmlessly vented overboard"), 5-15 (S-II "The tanks are vented by opening the tank vent ...


4

The payload fairings (containing the payload) are supplied with cool dry air while the rocket is on the launch pad. I doubt whether two hoses are ever provided; one for the air to enter and the other for the air to leave the fairing. There doesn't seem to be any reason why the air couldn't just vent through vent holes in the fairing. I went through a few ...


4

On the rocket, it's going to be a sufficiently reinforced piece of the vehicle structure. I've attached a photo I took of the Saturn V in Houston with the relevant hard point on the first stage circled. Note in particular how thick the block of metal that gets clamped down is, and note its structural connection as it goes up the length of the rocket.


4

There are two aspects of the Starship Orbital Launch Tower that are different from earlier launch towers, but neither of them have to do with the claw or the umbilical connections. The first aspect is the time frame in which the tower specifically, and the whole Orbital Launch Pad (including the Orbital Launch Mount and the tank farm) in general were ...


3

Roughly by how many degrees does the strongback tilt back during liftoff? For the Falcon 9 at Kennedy Space Center LC-39A and Cape Canaveral Space Force Station SLC-40: "Arms" open at about T-00:04:05 Leanback to about 2.5° from T-00:03:45–T-00:03:15 Fallback to about 45° from T-00:00:00–T+00:00:05 For the Falcon 9 at Vandenberg Space Force Base ...


3

During the Apollo program, the Saturn vehicle was stacked on the mobile launcher platform. Thus, a platform was in use starting from the stacking of the S-1C stage. This table provides a detailed timeline for each Saturn V launch vehicle and the platform used: Mission Stacking start ML ML in use* Launch date Apollo 4 27 Oct 1966 1 1 9 Nov 1967 Apollo 8 30 ...


2

Yes. I really wanted to just answer that one word, but it does not quite allow it. The good news is that the problem they encountered in the SN8 static fire led them to armour some lines that they thought were vulnerable, sooner than expected. This also suggests that the engines themselves may not be too vulnerable, rather it is the control lines (electric, ...


1

You're talking about an active structure. These have been proposed, but magnetic levitation is simply not strong enough. When applied to a launch assist structure, it is sometimes referred to as a Space Fountain. Rather than magnetic levitation, the proposed mechanism is accelerating pellets: Small metallic pellets by the millions would be shot up to a &...


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