Shuttle test flights?

[Chuck Buckley]

In article <4t3vuc$s...@nntp.crl.com>,
Stuart Brownley <st...@ozemail.com.au> wrote:
>Hope someone can shed some light over here!
>
>It has come to my attention that pre-Shuttle, all U.S. manned spacecraft
>(Mercury, Gemini & Apollo) were given unmanned flight tested at least once
>before someone was strapped to the rocket.
>
>Come 1981, John Young & Robert Crippen climed abord Columbia for it's (and
>the program's) maiden voyage. Why was the Shuttle not test flown without a
>human payload first?
>
>Was NASA so supremely confident in its new manned craft,

No.

>did budget
>restrictions not allow the 'luxury' of an unmanned test

Yes.

>or were there other
>reasons?
>

Yes.

The shuttle, as originally envisioned, would have been fully automated.
This would include take-off and landings. Now, they needed to develope and test
the software. This they were doing. But, a number of factors came into play.
They were *way* behind schedule and were taking heat. They did not have the
software completely tested. (I believe. I do know the confidence in the
landing software was not high in many parts of the program). Their budget did
not allow for additional staff and they were over-budget in any case. So, they
decided to use the pilots for the first few missions. This, they tried to
turn into good PR by emphasizing the pilot's input and importance to the
landing. Each of the next few flights would incrementally use the landing
software to a greater extent. By the 4th, or so, landing, they were fully
automated.

So, to sum up... NASA used a manned mission due to the necessity of getting
the system back on track in the shortest period of time, to allow a
phase-in of a new landing system, and for favorable PR.

--
Charles Buckley | I took a multiple choice test once:
cbuc...@swttools.fc.hp.com | I checked "All of the Above"...
(970) 229-7607 | "None of the Above"..
I definately do not speak for HP | Then I set the test on fire

[Mary Shafer]

It's a good thing that STS-1 was manned; they almost lost the vehicle
on the first energy-management bank reversal. Sideslip was about
three times what was predicted and the motion more poorly damped. In
addition, sideslip exceeded the limit (set because of heating
considerations) by at least a degree.

Why did the automated system do so badly? Because L_YJ, rolling
moment due to yaw jet, turned out to have twice the magnitude, with
the opposite sign, of the predicted value and C_l_\beta, coefficient
of rolling moment due to angle of sideslip and better known as
dihedral effect, was over-predicted by about a third.

They also maxed out the bodyflap because the predictions of the
longitudinal aerodynamic center-of-pressure location were incorrect.
This was because C_m_0, pitching moment bias, was mispredicted.

Read "Extraction of Stability and Control Derivative From Orbiter
Flight Data", Iliff and Shafer, NASA TM 4500, June, 1993, for more
details

--
Mary Shafer NASA Dryden Flight Research Center, Edwards, CA
SR-71 Flying Qualities Lead Engineer Of course I don't speak for NASA
sha...@ferhino.dfrc.nasa.gov DoD #362 KotFR
URL http://www.dfrc.nasa.gov/People/Shafer/mary.html
For personal messages, please use sha...@ursa-major.spdcc.com

[Thomas J. Frieling]

In article <SHAFER.96J...@ferhino.dfrf.nasa.gov> sha...@ferhino.dfrc.nasa.gov (Mary Shafer) writes:
>
>It's a good thing that STS-1 was manned; they almost lost the vehicle
>on the first energy-management bank reversal. Sideslip was about
>three times what was predicted and the motion more poorly damped. In
>addition, sideslip exceeded the limit (set because of heating
>considerations) by at least a degree.

Are you saying John Young took over manual control at this point and saved
the vehicle (not to mention their hides)?

[Mary Shafer]

On Fri, 26 Jul 1996 12:12:27 eastern, tfri...@catfish.bbc.peachnet.edu (Thomas J. Frieling) said:

Ty> In article <SHAFER.96J...@ferhino.dfrf.nasa.gov> sha...@ferhino.dfrc.nasa.gov (Mary Shafer) writes:
>
>It's a good thing that STS-1 was manned; they almost lost the vehicle
>on the first energy-management bank reversal. Sideslip was about
>three times what was predicted and the motion more poorly damped. In
>addition, sideslip exceeded the limit (set because of heating
>considerations) by at least a degree.

Ty> Are you saying John Young took over manual control at this point and saved
Ty> the vehicle (not to mention their hides)?

They let the autopilot fly the subsequent maneuvers, with their hands
poised over the RHCs, ready to trip of the system and hand-fly the
maneuvers. Fortunately, the vehicle was pretty much deadbeat in the
thicker atmosphere encountered as it descended. In subsequent
flights, the initial maneuvers were hand flown, until the FCS was
updated (which didn't happen earlier than the sixth flight and may
have been delayed until a mid-teens flight). You can find more
details in Iliff and Shafer, "Extraction of Stability and Control
Derivatives From Orbiter Flight Data", NASA TM 4500, June 1993.

John Young and Bob Crippen described the reentry in their paper at the
1981 SETP Symposium, "Spaceshic Columbia's First Flight". This
particular incident is reported rather drily, but they exhibited a
great deal more excitement in the actual presentation.

[Joshua Powers]

In article <SHAFER.96...@ferhino.dfrf.nasa.gov>,
sha...@ferhino.dfrc.nasa.gov says...

>
>On Fri, 26 Jul 1996 12:12:27 eastern, tfri...@catfish.bbc.peachnet.ed
>u (Thomas J. Frieling) said:
>
>Ty> Are you saying John Young took over manual control at this point a
>nd saved
>Ty> the vehicle (not to mention their hides)?
>
>They let the autopilot fly the subsequent maneuvers, with their hands
>poised over the RHCs, ready to trip of the system and hand-fly the
>maneuvers. Fortunately, the vehicle was pretty much deadbeat in the
>thicker atmosphere encountered as it descended. In subsequent
>flights, the initial maneuvers were hand flown, until the FCS was
>updated (which didn't happen earlier than the sixth flight and may
>have been delayed until a mid-teens flight). You can find more
>details in Iliff and Shafer, "Extraction of Stability and Control
>Derivatives From Orbiter Flight Data", NASA TM 4500, June 1993.
>

When was manual control taken on those early flights (before the
software upgrade). Earlier than Mach 1 / 50K as is cuirrently the
standard?