The Energia had SSTO capability?!?

I was looking up info on the RD-0120 analogue of the shuttle SSME's
when I came across this:

Energia EUS.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 77,000/7,000 kg.
Thrust 1,962.03 kN. Vacuum specific impulse 455 seconds."
http://www.astronautix.com/stages/eneiaeus.htm

But this is a better than 10 to 1 mass ratio for a LH2/LOX engine.
That's sufficient for a SSTO.
Actually the Energia core also appears to have SSTO capability:

Energia Core.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 905,000/85,000 kg.
Thrust 7,848.12 kN. Vacuum specific impulse 453 seconds."
http://www.astronautix.com/stages/eneacore.htm



Bob Clark

On Sep 29, 1:17*pm, Robert Clark wrote:
I was looking up info on the RD-0120 analogue of the shuttle SSME's
when I came across this:

Energia EUS.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 77,000/7,000 kg.
Thrust 1,962.03 kN. Vacuum specific impulse 455 seconds."http://www.astronautix.com/stages/eneiaeus.htm

But this is a better than 10 to 1 mass ratio for a LH2/LOX engine.
That's sufficient for a SSTO.
Actually the Energia core also appears to have SSTO capability:

Energia Core.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 905,000/85,000 kg.
Thrust 7,848.12 kN. Vacuum specific impulse 453 seconds."http://www.astronautix.com/stages/eneacore.htm


Actually, the Energia core stage has the same problem as the shuttle
+ET: the hydrogen fueled engines do not have enough thrust alone to
lift off the vehicle from the ground. That is why they both use
boosters, solids for the shuttle, liquid fueled ones for Energia.
The RD-0120 has a sea level thrust of 154,702 kgf, for a total thrust
of 600,000 kgf for the four engines on the Energia core, not enough to
lift the 900,000+ kg Energia core stage gross mass:

RD-0120
"Thrust (sl): 1,517.100 kN (341,058 lbf). Thrust (sl): 154,702 kgf.
Engine: 3,450 kg (7,600 lb). Chamber Pressu 218.00 bar. Area Ratio:
85.7. Thrust to Weight Ratio: 57.97. Oxidizer to Fuel Ratio: 6."
http://www.astronautix.com/engines/rd0120.htm

However, the thrust of the single RD-0120 on the Energia EUS upper
stage is well above that needed to lift its 77,000 kg gross mass.


Bob Clark

On 30/09/2010 3:17 AM, Robert Clark wrote:
I was looking up info on the RD-0120 analogue of the shuttle SSME's
when I came across this:

Energia EUS.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 77,000/7,000 kg.
Thrust 1,962.03 kN. Vacuum specific impulse 455 seconds."
http://www.astronautix.com/stages/eneiaeus.htm

But this is a better than 10 to 1 mass ratio for a LH2/LOX engine.
That's sufficient for a SSTO.
Actually the Energia core also appears to have SSTO capability:

Energia Core.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 905,000/85,000 kg.
Thrust 7,848.12 kN. Vacuum specific impulse 453 seconds."
http://www.astronautix.com/stages/eneacore.htm



Bob Clark

There's not a lot of point in building disposable SSTOs.

Sylvia.

On Sep 30, 4:07*am, Sylvia Else wrote:
On 30/09/2010 3:17 AM, Robert Clark wrote:



I was looking up info on the RD-0120 analogue of the shuttle SSME's
when I came across this:

Energia EUS.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 77,000/7,000 kg.
Thrust 1,962.03 kN. Vacuum specific impulse 455 seconds."
http://www.astronautix.com/stages/eneiaeus.htm

But this is a better than 10 to 1 mass ratio for a LH2/LOX engine.
That's sufficient for a SSTO.
Actually the Energia core also appears to have SSTO capability:

Energia Core.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 905,000/85,000 kg.
Thrust 7,848.12 kN. Vacuum specific impulse 453 seconds."
http://www.astronautix.com/stages/eneacore.htm


There's not a lot of point in building disposable SSTOs.

Sylvia.

The Isp of the SSME's and RD-0120's are so high that at a 10 to 1
mass ratio you could still carry significant payload even with reentry
and landing equipment.
Note also a key fact about SSTO's is that the delta-V requirement for
a round-trip mission from LEO to the lunar surface is a little less
than that for flights from Earth's surface to LEO. Then if you could
do orbital refueling, you could have a single, reusable vehicle that
does lunar missions. This important capability about SSTO's is
mentioned in G. Harry Stine's very nice book "Halfway to Anywhe
Achieving America's Destiny in Space" :

"...an SSTO that is refueled in orbit has the capability to fly to the
Moon, land, lift off, and fly back without additional refueling."
Halfway to Anywhe Achieving America's Destiny in Space, p. 220.
http://www.amazon.com/dp/0871318474?...0YPRN8S9Y83MB&

A table that gives the delta-V budget for trips in the Earth-Moon
system is given he

Delta-V budget.
Earth–Moon space.
http://en.wikipedia.org/wiki/Delta-v...0.93Moon_space

From this you can calculate that the delta-V for a round trip from
LEO to the lunar surface is less than that for getting to LEO.
I has been argued that SSTO's are not economical. But that such a
vehicle with orbital refueling could also be used for lunar missions
changes the economic equations significantly.


Bob Clark

On 8/10/2010 9:03 AM, Robert Clark wrote:
On Sep 30, 4:07 am, Sylvia wrote:
On 30/09/2010 3:17 AM, Robert Clark wrote:



I was looking up info on the RD-0120 analogue of the shuttle SSME's
when I came across this:

Energia EUS.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 77,000/7,000 kg.
Thrust 1,962.03 kN. Vacuum specific impulse 455 seconds."
http://www.astronautix.com/stages/eneiaeus.htm

But this is a better than 10 to 1 mass ratio for a LH2/LOX engine.
That's sufficient for a SSTO.
Actually the Energia core also appears to have SSTO capability:

Energia Core.
"Lox/LH2 propellant rocket stage. Loaded/empty mass 905,000/85,000 kg.
Thrust 7,848.12 kN. Vacuum specific impulse 453 seconds."
http://www.astronautix.com/stages/eneacore.htm


There's not a lot of point in building disposable SSTOs.

Sylvia.

The Isp of the SSME's and RD-0120's are so high that at a 10 to 1
mass ratio you could still carry significant payload even with reentry
and landing equipment.
Note also a key fact about SSTO's is that the delta-V requirement for
a round-trip mission from LEO to the lunar surface is a little less
than that for flights from Earth's surface to LEO. Then if you could
do orbital refueling, you could have a single, reusable vehicle that
does lunar missions. This important capability about SSTO's is
mentioned in G. Harry Stine's very nice book "Halfway to Anywhe
Achieving America's Destiny in Space" :

"...an SSTO that is refueled in orbit has the capability to fly to the
Moon, land, lift off, and fly back without additional refueling."
Halfway to Anywhe Achieving America's Destiny in Space, p. 220.
http://www.amazon.com/dp/0871318474?...0YPRN8S9Y83MB&

A table that gives the delta-V budget for trips in the Earth-Moon
system is given he

Delta-V budget.
Earth–Moon space.
http://en.wikipedia.org/wiki/Delta-v...0.93Moon_space

From this you can calculate that the delta-V for a round trip from
LEO to the lunar surface is less than that for getting to LEO.
I has been argued that SSTO's are not economical. But that such a
vehicle with orbital refueling could also be used for lunar missions
changes the economic equations significantly.


Bob Clark


It's not that I'm arguing that SSTOs are inherently uneconomic, but
there has to be a cost justification for hauling the entire launcher
into orbit. The simple justification is that it will all come back
intact and can thus be used again, much like an airliner.

But if you're going to trash it anyway after one use, then dropping bits
off before reaching orbit gives a higher payload. To justify not doing
that requires that it be cheaper to build a larger SSTO launcher than a
smaller multiple stage launcher, where both achieve the same payload.
Multi staging has complexities, and therefore costs, but it also avoids
some, such as the need for nozzles that handle ambient pressures from
sea level to vacuum.

Sylvia.