VSS Enterprise completes first flight under its carrier aircraft

On 4/2/2010 12:49 PM, Greg D. Moore (Strider) 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?

It makes glide landing a lot easier. ;-)
The thing might be able to survive a belly-flop into the atmosphere with
the wings blown off, but in a badly charred condition.
Although the wings do add a lot of drag on the way down, they also add
weight, especially when the up-swept rear sections are added to the
equation during reentry.
Going with the wing jettison idea, at the same time the wings would be
blown off some sort of heat-resistant drogue chute would be deployed
from the top bay where the emergency chute would be stored, both to slow
the fuselage's descent and keep it belly-side-down on the way in.
What you don't want to happen is ending up with one wing up and the
other down at any point during the reentry or return to base.
The parachute would let you keep both wings in the up position if one
failed to fold down correctly after reentry. Once you were fairly low
you could jettison them and deploy the chute. You might hit pretty hard,
but that would be better than spinning in like a bird with a broken wing.

Pat

On 3/04/2010 11:26 AM, Pat Flannery wrote:

The parachute would let you keep both wings in the up position if one
failed to fold down correctly after reentry.

I don't see that happening. The mechanism is surely a bar (presumabably
implemented as a tube) that passes through the fuselage, but outside the
pressure hull, and to which the wings are attached. It would be rotated
by redundant actuators. The major design issue would be handling a
jammed actuator.

Structural failure would be a problem, but it always is, and is
frequently not survivable in a conventional aircraft either.

If, despite the redundancy, it proved impossible to move the wings to
the rentry position, then the problem would be that the craft would
enter the lower atmosphere at too high a speed. Perhaps a jetisonable
drogue shoot could be provided as backup.

If the wings can't be returned to flying position, then you need the
parachute to rescue the entire vehicle.

Either way, blowing the wings off is either contraindicated, or at least
not useful.

Now all you have to worry about is the shutes deploying when they shouldn't.

Sylvia.

On 3/04/2010 10:35 AM, Pat Flannery wrote:
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.

I'd be more concerned about the aerodynamic loads.

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

On Fri, 02 Apr 2010 18:47:54 +0000, 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?

rick jones

Heat Shielding?! They don't need heat shielding.

Rick Jones writes:
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

That was my first thought too! Any landing you can laugh about, is a
good landing, even if it kills you! :-)

However if you think emergency depres recovery is no *laughing* matter,
why not bleed some of the extra NO2 through a scrubber?

How large a hole do you need to recover from?

Most commercial suppliers of NOx scrubbers seem to rely on a packing bed
and expect gravity to be available, so this might take some work to
build something that is purely pressure based.

http://www.ecologixsystems.com/wet_s...s_tower_tm.php

OTOH it might be cheaper/easier to just have a tank of O2 or compressed
air available to handle this. If you go the compressed air route, you
should take along some cigarettes. If the leak is a slow one, (and assuming
these are the only kind that will be 'recoverable' from anyway) light 'em
up when you got a leak so you can find the hole and patch it.

2nd hand smoke might kill you in 20 years, rapid depress can do so in
minutes.

Now that I've figured out a *very* good reason to take cigarettes along,
I just have to figure out the beer angle...

;-)

Dave

In sci.space.history message , Fri, 2
Apr 2010 18:45:38, Rick Jones posted:

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

Making them cough their lungs out will be a good distraction, and is
possibly less uncomfortable as the pressure drops. The difference
between nitrogen dioxide and nitrous oxide is considerable; perhaps you
meant the latter - N2O. Consult Wikipedia for retails.


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Web URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.
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Pat Flannery wrote:

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.

I don't know whether any airliners have escape systems for passengers that can work while the plane is in the air. If
this is so, I see no reason for a passenger-carrying spacecraft to have them. Other than politics.

Pat Flannery wrote:

No, it's the entire tail boom with the vertical and horizontal control
surfaces on it, with the closest analogy being to the folding wing on a
naval aircraft or the swing wing on a F-14 or F-111.

With a car, half of the contact area is involved in steering, so it had better work every time.

On 4/2/2010 2:11 PM, Rick Jones wrote:

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.

Peak g's are supposed to be around 6.
That's not high by fighter pilot standards, but twice what the Shuttle
ever has to deal with, and enough that passenger health requirments
could be pretty high.
What to make of claims that it can reenter in any attitude and land
safely with "catastrophic damage" is anyone's guess:
http://www.spaceshiptwo.net/
Maybe they _are_ going to put some sort of emergency parachute system on it?

Pat

On 4/2/2010 3:59 PM, Fevric J. Glandules wrote:


or the rocket engine blowing up for that matter.

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

"About zero", I like that.
He's still using one of those Pentium 486DX chips in his computer, isn't
he? :-D
Let's see...total area of Northern Atlantic Ocean...total area of
Northern Atlantic Ocean covered with icebergs on great circle route from
Southampton to New York City in April...oh hell, it will be nearly
completely safe.


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?

No, it's the entire tail boom with the vertical and horizontal control
surfaces on it, with the closest analogy being to the folding wing on a
naval aircraft or the swing wing on a F-14 or F-111.


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.

I'm not worried about it running into something up there, but rather
something going wrong with the engine that compromises the pressure
integrity of the passenger cabin, or some sort of structural failure
that does the same. There are going to be wires that penetrate the
pressure cabin's walls, and if the seal on one of those fails,
particularly in a area where you can't get at it - like under the
control panel, you've got a real problem on your hands.
There's also the question of how well the composite fuselage is going to
tolerate repeated firings of the rocket engine and their associated
high-frequency vibrations, as well as shockwaves from the engine exhaust
impinging on the tail booms and that's relationship to structural fatigue.

Pat