From: Mary Shafer <shafer@orville.dfrc.nasa.gov>
Newsgroups: sci.space.shuttle
Subject: Re: STS-1 crew selection
Date: 13 Oct 2000 16:51:44 -0700

"wolfshadow4" <wolfshadow4@email.msn.com> writes:

> > On Thu, 12 Oct 2000 11:51:28 +1100, "Justin Wigg"
> > <justinwigg@yahoo.com> wrote:
> > >Mary, are you implying that ALT-5 cast a doubt over Fred's abilities
> > >in the minds of others or in his?  (I am assuming by mentioning ALT-5
> > >you are talking about the touch and bounce landing?)

> I have read about (and seen footage of) the landing, but this is the
> first time that I have heard Haise been criticised about this,
> rather than it being just seen as a normal part of testing a
> newly-built air / space craft in flight tests. Can anyone confirm
> that Haise was criticised over this?

Actually, well-designed aircraft don't PIO, so it's not supposed to be
a normal part of flight test.  Not that the YF-16 or F-18 PIOs didn't
happen, of course.  The first was caused by too-high gains in the feel
system and the second by time delay in the FCS.

The Golden-Arm test pilots are supposed to notice that they're PIOing
and back out of the loop to stop it while still accomplishing the
task.  Therefore, the pilot of the YF-16 ended up converting a
high-speed taxi test into the first flight, when he decided, after
scraping off various bits of the airplane, that he'd be safer away
from the hard, unforgiving ground.  The F-18 didn't exhibit its
problem until the sea trials started, at which point it was flying
toward a ramp strike before the pilot and the LSO waved off the trap.

Haise wasn't criticized for PIOing the Orbiter, so far as I know, as
the fault lay with the vehicle, not the pilot.  However, he may have
lost some of his confidence in the design of the vehicle, which is
what I was speculating about.  After all, if they can't even design an
FCS that doesn't PIO so readily, what else might they have done wrong?

--
Mary Shafer
shafer@orville.dfrc.nasa.gov Of course I don't speak for NASA
Senior Handling Qualities Research Engineer
NASA Dryden Flight Research Center, Edwards, CA
For non-aerospace mail, use shafer@spdcc.com please

From: Mary Shafer <shafer@orville.dfrc.nasa.gov>
Newsgroups: sci.space.shuttle
Subject: Re: STS-1 crew selection
Date: 13 Oct 2000 16:36:40 -0700

Don Sterner <dsterner1@yahoo.com> writes:

> On Thu, 12 Oct 2000 11:51:28 +1100, "Justin Wigg"
> <justinwigg@yahoo.com> wrote:
>
> >"Mary Shafer" <shafer@orville.dfrc.nasa.gov> wrote in message
> >news:u0lmvvb697.fsf@orville.dfrc.nasa.gov...
> >
> >> ALT-5 probably affected one of them.
> >
> >Mary, are you implying that ALT-5 cast a doubt over Fred's abilities in the
> >minds of others or in his?  (I am assuming by mentioning ALT-5 you are
> >talking about the touch and bounce landing?)
>
> And touch and bounce and touch and bounce and touch and
> bounce......
>
> From what we were told, the control inputs were getting quite
> extreme before Fullerton yelled at him to get his hands off of
> the stick. They spent weeks after that flight trying to duplicate
> it in the simulators. I don't believe anybody ever succeeded.

We certainly did, both in the ground-based simulators and in the
TIFS.  It was a classic time-delay-induced PIO, augmented by body flap
rate limiting and the dynamic characteristics of the delta wing.

Inputs don't have to be large to cause a PIO, just frequent.  In fact,
we fixed the problem with the FCS by adding a bandaid PIO suppressor
that reduced the gain on pilot inputs when the frequency of those
inputs increased.  Move the stick too fast and the PIOS filter cuts
input authority to match.

--
Mary Shafer
shafer@orville.dfrc.nasa.gov Of course I don't speak for NASA
Senior Handling Qualities Research Engineer
NASA Dryden Flight Research Center, Edwards, CA
For non-aerospace mail, use shafer@spdcc.com please