On Jun/21/2020 at 12:09, Jeff Findley wrote :
In article , says...

On 2020-06-19 7:46 PM, Alain Fournier wrote:
Wow, you actually saw the moon missions live. You must be an old man.

Not to mention witnessing, in person, the launch of Columbia on STS-1.

I'm 51, so don't remember Apollo at all. But I do remember STS-1 and
beyond. STS-1 was ground breaking for its time. Unfortunately, the
press never picked up on the many things that went wrong with STS-1
besides perhaps the obvious missing silica tiles that fall off. Even
NASA still isn't terribly forthcoming about all of the issues. Cite:

https://www.nasa.gov/centers/dryden/...lls_sts-1.html

No mention of the body flap (that was almost a very bad day) or the
flight control system issues. Here is a cite for the body flap issue:

First Time Lucky: The Space Shuttle?s Dicey Inaugural Mission
BY TERRY DUNN ON JAN. 16, 2018 AT 8 A.M.
The story of STS-1.
https://tinyurl.com/ybvsthrh

Cite for the flight control system issue (Mary Shafer used to be a
regular poster here):

Extraction of stability and control derivatives from orbiter flight data
Author and Affiliation:
Iliff, Kenneth W. (NASA Hugh L. Dryden Flight Research Facility,
Edwards, CA, United States)
Shafer, Mary F. (NASA Hugh L. Dryden Flight Research Facility,
Edwards, CA, United States)
https://ntrs.nasa.gov/search.jsp?R=19940006252
https://ntrs.nasa.gov/archive/nasa/c...9940006252.pdf

Stability of an aircraft/spacecraft at high mach numbers is a bigger
problem than most believe. I had a friend who did computer fluid
dynamics for the European Hermes spacecraft programme in the late 1980s
and early 1990s. He was supposed to confirm the stability of the
spacecraft design. He told his bosses that his computations were not
conclusive and that the vehicle, as designed, was probably stable enough
but it wasn't a sure thing. He recommended tweaking the design to make
it more stable. That, together with other modifications asked by other
people working on the project, added delays and additional costs. The
programme was scrapped before my friend had a design he could guarantee
was stable.

When NASA designed the space shuttle, they had nowhere near the
computing power my friend had for Hermes. (We were jealous of the
computers he was using with several GB of RAM, most people at the time
had computers with a few MB of RAM, I was working on a computer that
most people thought was amazing with 600 MB of RAM, that computer I was
working on had cost hundreds of thousands of dollars.) NASA had done a
lot of wind tunnel testing for the Shuttle, but that doesn't allow for
as much iterations as computational fluid dynamics. All worked out well
for the Shuttle. That's what my friend was saying would happen with
Hermes, he was saying it was probably stable but he wasn't sure. So if
Hermes had flown as it was first designed, the outcome would probably
have been as for the Shuttle: it works, now that we have flown it, we
know it.

Note that capsules are much easier in this respect.


Alain Fournier