News ATK & Astrium Liberty™ Launch Vehicle

[T.Neo]

Actually, if the ESA wanted a manned spaceflight system, they'd human-rate their existing launcher (originally designed to be human-rated) and build a spacecraft utilising their already-existing ATV technology.

Not only far more technologically feasible, but actually physically possible (which is always a bonus :shifty.

 

[RGClark]

...
Even if you assume that the structural mass does not increase for adding a second engine (which would), you would get less thrust force than weight force at sea level thrust (but only 11 kN). Even if you would launch without the 13 tons of Payload by the Dragon, a naked stage with magic mass-less fairing, the acceleration at launch would be 0.61 m/s² - after 100 seconds of flight, the rocket would finally pass 4 km altitude...

Why are you saying 13 tons? The Dragon dry mass is in the range of 4 tons.

Bob Clark

 

[Urwumpe]

Why are you saying 13 tons? The Dragon dry mass is in the range of 4 tons?

Bob Clark

The dry mass. Exactly that. Not the launch mass. And about 4 tons is the mass of the Dragon boiler plate, that was launched first, not the full spacecraft (with payload/crew and consumables) as launched to the ISS. That is somewhere between 10 tons and 13 tons (maximum payload of the Falcon 9), even without launch escape system. With launch escape system, 13 tons would even be almost the lower estimate.

(Note that it wouldn't even change a thing, if the dragon capsule would have zero mass. While the rocket could then lift off VERY slowly, it would have too many gravity losses because of its slow acceleration and only reach a very low suborbital trajectory. The thrust wouldn't even be enough to exceed the speed of sound before enough fuel is burned and altitude gained)

 

[Hlynkacg]

Seems to imply they won't be developing it.
The ESA if they wanted their own manned space flight system could get it quickly by using the Ariane 5 core stage alone with the addition of a second Vulcain engine, capable of carrying a Dragon-sized capsule to orbit.
Even the Dragon is larger than it needs to be just to LEO. If you made a capsule half its size to carry just three passengers, then by cutting the size of the Ariane 5 core to half-size you could loft the half-size capsule to orbit on just a single Vulcain engine.


Bob Clark

Oh for sake :facepalm:

where do you plan to put that second engine?

As T Neo already said, if the ESA wanted a manned spaceflight system, they'd design (or buy) a capsule and put it on top of an Ariane 5.

 

[RGClark]

The dry mass. Exactly that. Not the launch mass. And about 4 tons is the mass of the Dragon boiler plate, that was launched first, not the full spacecraft (with payload/crew and consumables) as launched to the ISS. That is somewhere between 10 tons and 13 tons (maximum payload of the Falcon 9), even without launch escape system. With launch escape system, 13 tons would even be almost the lower estimate.

So as not to derail the thread topic, I sent the response to the
A low cost, all European, manned launcher thread.

Bob Clark

---------- Post added at 03:07 AM ---------- Previous post was at 02:49 AM ----------

Actually, if the ESA wanted a manned spaceflight system, they'd human-rate their existing launcher (originally designed to be human-rated) and build a spacecraft utilising their already-existing ATV technology.
Not only far more technologically feasible, but actually physically possible (which is always a bonus :shifty.

Response on "A low cost, all European, manned launcher" thread.

Bob Clark

---------- Post added at 08:52 AM ---------- Previous post was at 03:07 AM ----------

Spaceflight Now: ATK 'moving on' after Liberty commercial proposal loss

Odd. The Spaceflightnow.com site is down now.

Bob Clark

 

[Hlynkacg]

I don't usually do this but...

Mr. Clark,

Even if we were to accept your wildly optimistic mass values and over simplified formulae your proposal would still be unworkable.

You see, two molecules cannot cohabitate the same volume.

The single Vulcain engine and it's associated overhead (pumps, gimbal actuators, etc...) occupy the entirety of the ariane core's current thrust structure.

Even if it didn't it's engineering stand off radius is over two meters.

In other words you can not add a second engine withough first widening the stage by approximately .2 meters.

You use all the math in the world to prove that nolting a SSME to the back of my pickup truck would make it a SSTO but the real world doesn't work like that.

 

[RGClark]

I don't usually do this but...
Mr. Clark,
Even if we were to accept your wildly optimistic mass values and over simplified formulae your proposal would still be unworkable.
You see, two molecules cannot cohabitate the same volume.
The single Vulcain engine and it's associated overhead (pumps, gimbal actuators, etc...) occupy the entirety of the ariane core's current thrust structure.
Even if it didn't it's engineering stand off radius is over two meters.
In other words you can not add a second engine withough first widening the stage by approximately .2 meters.
You use all the math in the world to prove that nolting a SSME to the back of my pickup truck would make it a SSTO but the real world doesn't work like that.

Response on the A low cost, all European, manned launcher thread.

Bob Clark