Setback for Rutan

On Wed, 23 Jun 2004 07:38:39 -0600, "Jeff Crowell" wrote:

Peter Kemp wrote:
According to BBC reports quoting Rutan there were severe control
problems that forced the pilot (ok, ok, astronaut) to resort to backup
controls just after boost (uncommanded roll) and again near Apogee
(nothing specific mentioned).

From where I sit, let's call him a a pilot... he WAS driving, after all,
not just watching the pretty lights.

Melville and Rutan were on Leno last night, pilot said the problem
was with the trim system near/at apogee, not control system, though
ISTR someone mentioning right after the flight that they had had
some roll instability during the flight, and right after launch it looked
in the video as if the plane (spacecraft?) was rolling back and forth
about 40-50 degrees each way from vertical.


Jeff

At apogee there would be almost no control authority (lack of sufficient air
molecules). Do they have a thruster system for control at that altitude??

Al Minyard

Alan Minyard wrote:

At apogee there would be almost no control authority (lack of sufficient air
molecules). Do they have a thruster system for control at that altitude??

If there is *any* remotely usable control authority then the thing ain't
in space for any reasonable value of "space".

In article ,
Robert Briggs writes:
Alan Minyard wrote:

At apogee there would be almost no control authority (lack of sufficient air
molecules). Do they have a thruster system for control at that altitude??

If there is *any* remotely usable control authority then the thing ain't
in space for any reasonable value of "space".

A couple or three points:
Control Authority doesn't have to mean aerodunamic controls - SS1
has a cold-gas RCS system for attitude control a very low EAS.

There is no such thing a "a reasonable value of 'space'".
It's not like there's a definite dividing line between Atmosphere
adn Vacuum - the density of the atmosphere thrails off as height
increases, but it doesn't entirely go away. Aerodynamic drag, and
the variations in that that occur was the Earth's atmosphere expands
and contracts due to Solar Radiation, are a significant factor in
the lifetime of an orbiting satellite. (Remember Skylab). That
Orbital Decay that you hear so much of is mostly caused by
atmospheric drag.

(By the same token, I'd like to punch Eugene Sanger, or his
translators, in the nose for starting that whole like of crap about
"skipping" off the Earth's atmosphere with a lifting spacecraft. It
doesn't and can't happen that way. The only way to change your vector
with such a craft while re-entering is to fly up, rather than bounce
up - you've got to be flying fast enough, in thick enough air, to
allow a normal pull-up. (As a reference, note that Columbia had
almost reached an EAS that would have allowed a pull-up, but hadn't
yet))

The definition of where "space" starts is completely arbitrary. The
USAF specifies it as 50 miles MSL. The FAI specifies it as 100 km.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

In article ,
Alan Minyard writes:
On Wed, 23 Jun 2004 07:38:39 -0600, "Jeff Crowell" wrote:

Peter Kemp wrote:
According to BBC reports quoting Rutan there were severe control
problems that forced the pilot (ok, ok, astronaut) to resort to backup
controls just after boost (uncommanded roll) and again near Apogee
(nothing specific mentioned).

From where I sit, let's call him a a pilot... he WAS driving, after all,
not just watching the pretty lights.

Melville and Rutan were on Leno last night, pilot said the problem
was with the trim system near/at apogee, not control system, though
ISTR someone mentioning right after the flight that they had had
some roll instability during the flight, and right after launch it looked
in the video as if the plane (spacecraft?) was rolling back and forth
about 40-50 degrees each way from vertical.


Jeff

At apogee there would be almost no control authority (lack of sufficient air
molecules). Do they have a thruster system for control at that altitude??

Yes - there's a cold-gas RSC system. See my response to Jim Yanik's
post on this thread.


--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

On Wed, 23 Jun 2004 13:35:44 -0400, (Peter Stickney) wrote:

In article ,
Alan Minyard writes:
On Wed, 23 Jun 2004 07:38:39 -0600, "Jeff Crowell" wrote:

Peter Kemp wrote:
According to BBC reports quoting Rutan there were severe control
problems that forced the pilot (ok, ok, astronaut) to resort to backup
controls just after boost (uncommanded roll) and again near Apogee
(nothing specific mentioned).

From where I sit, let's call him a a pilot... he WAS driving, after all,
not just watching the pretty lights.

Melville and Rutan were on Leno last night, pilot said the problem
was with the trim system near/at apogee, not control system, though
ISTR someone mentioning right after the flight that they had had
some roll instability during the flight, and right after launch it looked
in the video as if the plane (spacecraft?) was rolling back and forth
about 40-50 degrees each way from vertical.


Jeff

At apogee there would be almost no control authority (lack of sufficient air
molecules). Do they have a thruster system for control at that altitude??

Yes - there's a cold-gas RSC system. See my response to Jim Yanik's
post on this thread.

Thanks for the info :-)

Al Minyard