Good point about the height differential.

It now occurs to me that shape might be an issue too. Falcon 9 is cylindrical while the SLS stack has a much more complicated cross-section that is also quite a bit more variable by height. The direction of the wind should matter too as the SLS stack presents a different silhouette at different angles of incidence, no doubt yielding quite different coefficients of drag – even the best of which seem likely to well exceed that of a Falcon 9.

These would not be issues exclusive to SLS. I think there are combinations of wind speed and direction that would preclude launching a Falcon Heavy from LC-39A while the launch of a Falcon 9 from SLC-40 would be fine. The now-retired Delta IV Heavy no doubt faced the same sorts of limitations.

Dick Eagleson: The update here says “cold temperatures and high winds” were the reason for the delay.

SLS is a much bigger rocket that Falcon 9. Moreover, during its transport from pad to VAB it is very exposed in a vertical position, and moving, though slowly. I can understand NASA’s caution.

Not that I’m complaining, mind you. Every delay increases the possibility that this mission will either slip well into 2026 or even not fly at all this year.

The leaks are in the **ground support equipment**, not the rocket. Once liftoff occurs, they don’t matter.

“”If moving the SLS back and forth to the launchpad is causing fuel leaks, what will the actual liftoff do?””

Daniel wrote:

“”Tony:
Shhhh…I don’t think you’re allowed to voice things like that.””

Well, as long as it reaches space semi-intact……………….

Liftoff is an entirely different thing. The leaks come from pumping hydrogen through the umbilical fuel lines to the tanks. Once filled they replenish the tanks during the countdown, as hydrogen bleeds off naturally.

Once launched however the fuel lines detach and the system runs internally.

Of much more concern during lift-off is the failure of helium to flow, as it is necessary to maintain pressure in the tanks so that the fuel can be pumped to the engines during flight. If it doesn’t flow, the fuel doesn’t reach the engines, and you have a launch failure.

Stuff Elon Should Have Said, p. 37