SS1 -- one down, one to go!

On 30 Sep 2004 07:10:36 -0700, in a place far, far away,
made the phosphor on my monitor glow in such a
way as to indicate that:

My opinion, after watching the entire flight on video,
is that the SS1 design has a built-in control problem
that makes it very difficult to fly, especially at
higher altitudes. A computer might be able to fly it
straight, but no stick and rudder pilot is perfect
enough to fly it pretty every time.

I don't think it's altitude. The fact that it's happening later in
the burn could be because of nozzle erosion. I'm guessing that it
doesn't have enough RCS control authority to muscle past the
(unplanned) thrust asymmetries, and as Brett suggested, yaw and pitch
moments are getting coupled into roll. The pilot is probably fighting
to keep the nose pointed forward, and as Brett suggested, yaw and
pitch moments are getting coupled into roll.

If so, this is a problem that could be solved with a better engine
nozzle design.

On Thu, 30 Sep 2004 14:22:01 +0000, Rand Simberg wrote:

On 30 Sep 2004 07:10:36 -0700, in a place far, far away,
made the phosphor on my monitor glow in such a way
as to indicate that:


I don't think it's altitude. The fact that it's happening later in the
burn could be because of nozzle erosion. I'm guessing that it doesn't
have enough RCS control authority to muscle past the (unplanned) thrust
asymmetries, and as Brett suggested, yaw and pitch moments are getting
coupled into roll. The pilot is probably fighting to keep the nose
pointed forward, and as Brett suggested, yaw and pitch moments are
getting coupled into roll.

If so, this is a problem that could be solved with a better engine
nozzle design.

The nozzle is fine, it's symmetric. If it is cross coupling, it's probably
in yaw. The pitch plane is pretty symmetric also with respect to roll.

But in the yaw plane, the twin rudders are not symmetric. They are above
the cg of the spacecraft. Also, the top of the rudders are larger than the
bottom. So, an angle of side slip will also cause a rolling moment. Maybe
they could fix it by reducing the size of the rudders on the top, and
increasing the size on the bottom. This would bringing them closer to
being symmetric about the cg. That is, if there is enough ground
clearance.

Or, possibly add small steering vains at the end of the nozzle to use
thrust to control roll during powered flight.

Craig Fink
Badnarik for President http://www.badnarik.org
http://www.metrowestdailynews.com/ar...rticleid=78317
Badnarik and others, coming to a PBS program near you! Tonight. Don't go
to the polls as ignorant as CNN, MSNBC, FOXNEW,... would like you to be.

"Rand Simberg" wrote in message
...
On Thu, 30 Sep 2004 13:22:55 +0200, in a place far, far away, "Tamas
Feher" made the phosphor on my monitor glow in

Remember what Korolev said: three successful unmanned flights for any
space hardware before people are allowed to ride it.

Well, if Korolev said it, it must be true...

Except for the Saturn V. Or the Shuttle.

Each Saturn V was flown only once

On Thu, 30 Sep 2004 15:19:38 GMT, in a place far, far away, Craig Fink
made the phosphor on my monitor glow in such a
way as to indicate that:

If so, this is a problem that could be solved with a better engine
nozzle design.

The nozzle is fine, it's symmetric.

Not after it erodes...

"Tamas Feher" writes:

Numerous news sites (Yahoo, BBC, Google, Reauters) reporting a
successful flight despite control problems

The SS1 may be destroyed on the next flight, I'm afraid. They had two
major flaws on two flights and their luck will run out .

Remember what Korolev said: three successful unmanned flights for any
space hardware before people are allowed to ride it. This is time-proven
wisdom.

But airplanes are exactly the opposite - *every* first flight has a pilot
aboard. And since SS1 is much more like an airplane than a traditional
spacecraft, should not the airplane rules apply?

Rutans are flirting with the devil when sending up known faulty craft,
which is outrageous. They will do irrepairable harm to private space
exploration.

No craft is ever perfect, even commercial airliners. They all have known
faults that can potentially kill you. Part of engineering is deciding
how to deal with each of these faults. Sometimes the answer is training
(don't do that), sometimes it's human interface (make the knobs different
so you don't mistakenly do A when you mean to do B, change the control
laws, etc.), and sometimes it's indeed to scrap the whole idea and start over.

The right people to make these decisions are (at least for a test plane)
the folks who built it and those who risk their life flying it. It's
certainly possible that they can be over enthusiastic, and believe that a
flaw can be lived with when it cannot, but it is their project, their lives,
and their decision. And in the long run, it may be better to learn all
you can from model one, before you build model two. Continued testing
may well reveal another flaw that would otherwise be built into model two
as well.

Finally, a crash of a test plane with a known flaw would hardly cause
irrepairable harm. It has happened may times in aviation, which is still
going strong. In fact, a crash due to a known flaw impedes progress
much less than a crash due to unknown or unforeseen reasons.

Lou Scheffer

On Thu, 30 Sep 2004 15:33:52 +0000, Rand Simberg wrote:

On Thu, 30 Sep 2004 15:19:38 GMT, in a place far, far away, Craig Fink
made the phosphor on my monitor glow in such a
way as to indicate that:

If so, this is a problem that could be solved with a better engine
nozzle design.

The nozzle is fine, it's symmetric.

Not after it erodes...

One of the articles said that they see the roll in their simulations. They
don't have eroded nozzles. Nonsymetrical erosion, or maybe nonsymetrical
burning of the rubber fuel in the motor. But, most if not all is in the
aerodynamic design.

http://www.space.com/missionlaunches...ht_040929.html

Pictures that show the wing and rudder above the cg, causing roll to be
coupled to angle of sideslip.

http://www.scaled.com/projects/tiero...eral/og_ff_800

http://www.scaled.com/projects/tiero...l/LANDING2_800

The rudders should be larger on the bottom not the top to reduce yaw/roll
coupling. It also looks like they have clearance to do this.

Craig Fink
Badnarik for President http://www.badnarik.org
http://www.metrowestdailynews.com/ar...rticleid=78317
Badnarik and others, coming to a PBS program near you! Tonight. Don't go
to the polls as ignorant as CNN, MSNBC, FOXNEW,... would like you to be.

h (Rand Simberg) wrote:

Remember what Korolev said: three successful unmanned flights for any
space hardware before people are allowed to ride it.

Well, if Korolev said it, it must be true...

Except for the Saturn V. Or the Shuttle.

Or Gemini-Titan.

D.
--
Touch-twice life. Eat. Drink. Laugh.

In article ,
"Neil Gerace" wrote:

"Rand Simberg" wrote in message
...
On Thu, 30 Sep 2004 13:22:55 +0200, in a place far, far away, "Tamas
Feher" made the phosphor on my monitor glow in

Remember what Korolev said: three successful unmanned flights for any
space hardware before people are allowed to ride it.

Well, if Korolev said it, it must be true...

Except for the Saturn V. Or the Shuttle.

Each Saturn V was flown only once

Uh, mm, I think in this case he means a particular _model_ of hardware
system. There were two successful unmanned flights of the Gemini -- but
not the _same_ CM -- before Grissom&Young.

And, were there at least two flights of Saturn V/Apollo "all-up" unmanned
before A8? I could be wrong.

As for the Shuttle, I guess we can't really count things like the piloted
drop tests. It's not like it couldn't have landed on its own, could it?
Even so, first time up, carrying a live crew. I was excited at the
prospect of finally getting to see STS fly "for real", but still the whole
time I was thinking "no previous unmanned all-up flight, man, this is
nuts".

--
"All over, people changing their votes,
along with their overcoats;
if Adolf Hitler flew in today,
they'd send a limousine anyway!" --the clash.
__________________________________________________ _________________
Mike Flugennock, flugennock at sinkers dot org
Mike Flugennock's Mikey'zine, dubya dubya dubya dot sinkers dot org

On Thu, 30 Sep 2004 16:46:22 -0400, in a place far, far away,
(Mike Flugennock) made the phosphor on my
monitor glow in such a way as to indicate that:

As for the Shuttle, I guess we can't really count things like the piloted
drop tests. It's not like it couldn't have landed on its own, could it?

Actually, it was exactly like that.

"Tamas Feher" wrote in message ...
Numerous news sites (Yahoo, BBC, Google, Reauters) reporting a
successful flight despite control problems

The SS1 may be destroyed on the next flight, I'm afraid. They had two
major flaws on two flights and their luck will run out .

Remember what Korolev said: three successful unmanned flights for any
space hardware before people are allowed to ride it. This is time-proven
wisdom.

That is Armadillo's explicit policy, but Burt made a conscious
strategic decision to require a human pilot for operation. I disagree
with that decision, but it is certainly defensible based on his
experience base and results.

Rutans are flirting with the devil when sending up known faulty craft,
which is outrageous. They will do irrepairable harm to private space
exploration.

I don't think you will find anyone actually in the business of working
towards private space exploration that thinks Burt is doing them harm.

Go Scaled!

John Carmack
www.armadilloaerospace.com