VSS Enterprise completes first flight under its carrier aircraft

On 4/1/2010 4:46 PM, Fevric J. Glandules wrote:


As *I* understand it, Concorde was designed to operate at or about
the Mach 2 "sweet spot" - the point at which it suddenly gets much
much more expensive to go faster, whereas getting from Mach 1.8 to
Mach 2 as a cruise speed just needs a small increment in expense.
And from there, AIUI, the speed pretty much dictates the altitude.

The primary reason for choosing Mach 2.02 as the max cruising speed was
to allow the airframe to be built out of aluminum alloys, at speeds
higher that heating was severe enough to require stainless steel or
titanium construction, and the development costs would go through the roof.

IIRC the aircraft would be in a steady climb once it got into
supercruise, as its fuel burnt off and it got lighter.


That would be the case, but it was designed to max out at 60,000 feet,
with a more normal flight level being 56,000 feet. The blood boiling
starts at 63,000 feet according to this:
http://www.globalsecurity.org/milita...324-afpn02.htm
That also points out that the U-2 pressure suits weigh 90 pounds each,
which would really cut into Space Ship 2's passenger capacity if they
decided to use that type.


If anything goes wrong with Space Ship 2's wing position before or after
reentry, then it's all over for everyone on board.

You might say the same thing about a 737's rudder going hard left.

True, but without a _lot_ of full altitude test flights, Virgin Galactic
doesn't know what the odds of that happening are...or the rocket engine
blowing up for that matter.
There is about zero flight experience with something like this outside
of the few Space Ship 1 flights and the X-15 program.
One thing that concerns me (besides the need to change the wing position
for reentry, then change it back for the glide landing) is that the
comparatively small cabin volume means a pretty small hole in its
pressure integrity could lead to a pretty fast depressurization, making
it impossible to get the passengers (with no pressure suits) back down
to a survivable altitude before the loss of pressurization causes mortal
injury.
So, would I consider it safe enough to personally fly on?
Well, the odds of surviving one flight are probably pretty good, so I
might try that...but I certainly wouldn't make it something I'd do every
day, and if I were one of its pilots I would sure want a full pressure
suit and a parachute...at the very least.

Pat

On 30/03/2010 5:44 AM, Pat Flannery wrote:
On 3/29/2010 6:24 AM, Jeff Findley wrote:

There are precious few ways you can safely experience high quality zero
gravity for more than say a couple of seconds at a time.

I'm still waiting for the first time one of the wings doesn't fold down
and lock after reentry.

It looks a simple enough mechanism, and no doubt there would be a
redundant latching and drive systems. And safeguards against unintended
operation, given that premature fold down might well be unsurvivable.


Note that they are following the Shuttle's lead here in not having any
escape system for the passengers, even to the point of not giving them
pressure suits and parachutes to bail out the side hatch with like the
Shuttle has.

Given the hazards associated with trying to get passengers out, and
having them land safely using parachutes, I suspect that any
monetary/weight penalty would be better used to increase the redundancy
so as to make parachutes unnecessary.

Perhaps a recovery parachute for the entire craft?

Sylvia.

In sci.space.history Pat Flannery wrote:

One thing that concerns me (besides the need to change the wing
position for reentry, then change it back for the glide landing) is
that the comparatively small cabin volume means a pretty small hole
in its pressure integrity could lead to a pretty fast
depressurization, making it impossible to get the passengers (with
no pressure suits) back down to a survivable altitude before the
loss of pressurization causes mortal injury.

So, on first detection of loss of cabin pressure above a survivable
altitude, open a valve from the engine's NO2 tank to feed NO2 ino the
cabin. It may not save any lives, but they may not mind as much

rick jones
--
Wisdom Teeth are impacted, people are affected by the effects of events.
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

In sci.space.history Pat Flannery wrote:
That's what I thought also; use shaped charges to blow the wings off
if they malfunction, and let the fuselage fall into the atmosphere
belly-first,

Given the point of the folding wings was to increase drag to lessen
the requirements for heat shielding, doesn't blowing the wings off
prior to re-entry mean a requirement to significantly beef-up the TPS
on the fuselage?

rick jones
--
firebug n, the idiot who tosses a lit cigarette out his car window
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

On 4/2/2010 12:24 AM, Sylvia Else wrote:

Given the hazards associated with trying to get passengers out, and
having them land safely using parachutes, I suspect that any
monetary/weight penalty would be better used to increase the redundancy
so as to make parachutes unnecessary.

Perhaps a recovery parachute for the entire craft?

That's what I thought also; use shaped charges to blow the wings off if
they malfunction, and let the fuselage fall into the atmosphere
belly-first, followed by releasing a parachute in its top and inflating
airbags housed in its landing gear wells. The seats could have some sort
of crushable honeycomb material mounted under them also to help prevent
injury to the occupant's spinal columns on landing.

Pat

Rick Jones wrote:
In sci.space.history Pat Flannery wrote:
That's what I thought also; use shaped charges to blow the wings off
if they malfunction, and let the fuselage fall into the atmosphere
belly-first,

Given the point of the folding wings was to increase drag to lessen
the requirements for heat shielding, doesn't blowing the wings off
prior to re-entry mean a requirement to significantly beef-up the TPS
on the fuselage?

That's sort of my thinking. That if you can survive w/o the folding wings
in the first place, why use them?

rick jones

--
Greg Moore
Ask me about lily, an RPI based CMC.

In sci.space.history "Greg D. Moore \(Strider\)" wrote:
Rick Jones wrote:
Given the point of the folding wings was to increase drag to
lessen the requirements for heat shielding, doesn't blowing the
wings off prior to re-entry mean a requirement to significantly
beef-up the TPS on the fuselage?

That's sort of my thinking. That if you can survive w/o the folding
wings in the first place, why use them?

Well, doesn't more drag higher-up mean fewer Gs and so a more
"comfortable" ride? Perhaps that is a "bonus" with it also enabling a
lesser TPS load. Riding SS2 isn't simply about "surviving" but also
enjoying the ride.

rick jones
--
No need to believe in either side, or any side. There is no cause.
There's only yourself. The belief is in your own precision. - Joubert
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

On 4/2/2010 10:47 AM, Rick Jones wrote:

Given the point of the folding wings was to increase drag to lessen
the requirements for heat shielding, doesn't blowing the wings off
prior to re-entry mean a requirement to significantly beef-up the TPS
on the fuselage?


It might get toasted on the way down, but still be survivable.
Speaking of the TPS, there is some sort of black coating on the belly of
Space Ship 2, but it's hard to tell if it's TPS or just black paint:
http://www.cbc.ca/world/story/2010/0...ctic-test.html

Pat

Pat Flannery wrote:

On 4/1/2010 4:46 PM, Fevric J. Glandules wrote:


As *I* understand it, Concorde was designed to operate at or about
the Mach 2 "sweet spot" - the point at which it suddenly gets much
much more expensive to go faster, whereas getting from Mach 1.8 to
Mach 2 as a cruise speed just needs a small increment in expense.
And from there, AIUI, the speed pretty much dictates the altitude.

The primary reason for choosing Mach 2.02 as the max cruising speed was
to allow the airframe to be built out of aluminum alloys, at speeds
higher that heating was severe enough to require stainless steel or
titanium construction, and the development costs would go through the roof.

Exactly my point. Costs dictated maximum speed, which dictated
altitude, not concerns about being above "blood-boiling altitude".

If anything goes wrong with Space Ship 2's wing position before or after
reentry, then it's all over for everyone on board.

You might say the same thing about a 737's rudder going hard left.

True, but without a _lot_ of full altitude test flights, Virgin Galactic
doesn't know what the odds of that happening are...

It *is* possible to build mechanical systems that Just Work.

or the rocket engine blowing up for that matter.

IIRC from Mike Melville's presentation there's about zero chance
of that happening.

There is about zero flight experience with something like this outside
of the few Space Ship 1 flights and the X-15 program.
One thing that concerns me (besides the need to change the wing position
for reentry, then change it back for the glide landing) is that the

It's just a control surface that's slightly larger and has a
greater degree of movement than we're used to - no?

comparatively small cabin volume means a pretty small hole in its
pressure integrity could lead to a pretty fast depressurization, making
it impossible to get the passengers (with no pressure suits) back down
to a survivable altitude before the loss of pressurization causes mortal
injury.

We're talking about a *very* small time-frame, and a very low altitude
in space terms. Space junk doesn't stay up for very long at that
height.

Rick Jones wrote:
In sci.space.history Pat Flannery wrote:
That's what I thought also; use shaped charges to blow the wings off
if they malfunction, and let the fuselage fall into the atmosphere
belly-first,

Given the point of the folding wings was to increase drag to lessen
the requirements for heat shielding, doesn't blowing the wings off
prior to re-entry mean a requirement to significantly beef-up the TPS
on the fuselage?

Worse, without the wings the fuselage would stabilize nose-first instead
of belly-first, resulting in high "eyeballs-out" G-force.

Better to keep the wings so as to keep the drag.