Eagle1Division
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Hello,
Normally I'm working on one project or another to pass time, in this case, I've ran into a fairly interesting idea...
So the Venture Star was a huge promise and a dream that ultimately failed. There are probably some folks around here that have more information on it than I do (which I would be interested in), but from what I understand the issue was technical problems with the LH2 fuel tank, because it required new materials to reach such a high mass ratio while providing the insulation and pressure containment.
So my idea was to add a booster. Okay, it wouldn't be an SSTO anymore, but:
+ The all-metal heat shield still drastically reduces turnaround time
+ A new liquid booster would have lift surfaces and a light heat shield to allow it to be fully reusable.
~The booster would be in an outline configuration, and sit on top of the Dual Star (over the payload bay, as depicted above), so that it doesn't have a chance of foam-strike on the all-metal heat shield.
+ Because the booster is fully reusable, the entire system still has all the advantages of an SSTO, without facing the issue of large mass ratio or extremes of the acceleration profile. Mating the booster to the vehicle would be trivial in comparison to the Shuttle's procedures.
The advantage of an SSTO is it's 100% reusability. That hasn't gone away. The booster in this case, if designed correctly (very heavily, that is), turnaround operations could be as easy as refilling the tanks, without major engine overhauls every flight. Because it's a booster and not the primary rocket, it can afford to be somewhat heavier, so extra mass, which means not working as near structural limits, means not such strict and comprehensive overhauls and maintenance will be required.
The Booster is a lifting body, it separates at the point where it can glide and land at the MARS (Mid-Atlantic Regional Spaceport) on [ame=http://en.wikipedia.org/wiki/Wallops_Island]Wallops Island[/ame]. This target can be reached after launching from the KSC at 42* inclination with a MECO at around ~2,500 to ~3,000 m/s.
This would restrict the missions to high-inclination orbits, but if a low inclination orbit is required, the booster could carry jet engines for a powered glide to Nova Scotia or a target on the west coast of Africa, depending on the inclination of the mission. This isn't too much of an exotic idea, the Buran spacecraft was designed to use a jet engine assisted glide, and they will only need to thrust the empty booster, which doesn't carry a large heat shield, meaning it would be extremely light.
With an ascent time of ~600 seconds, it would only need a mass ratio of 6 for the central stage. The booster will only need a Delta-Vee
I'll post more as I flesh out the idea more.
Same-day update:
Orbiter:
Delta-Vee: 7,640 m/s
Mass Ratio: 5.6767
ISP: 450 s
LOX/LH-2
Booster:
(Provides avg. 50% thrust)
Delta-Vee: 5,600 m/s
Mass Ratio: 8.275
ISP: 270 s
LOX/RP-1
Boost Delta-Vee: 1,400 m/s
Velocity at separation: 2,800 m/s
[As you'll notice, it's very easy to calculate separation velocity, boost D-v, and total D-v when the thrust is at exactly 1/2 ]
Q's:
Although Linear Aerospike nozzles are supposed to get a better ISP at every altitude, from the data provided, the SSME's actually have a better ISP than the Venture Star's RS2200 Aerospikes:
RS2200: http://www.astronautix.com/engines/rs2200.htm
SSME: http://www.astronautix.com/engines/ssme.htm
According to what I read, the Venture Star wouldn't use hypergolics. So what does it use for RCS then?
PS, if anyone noticed, the picture is of the SSTO from Ace Combat (5?).
---------- Post added at 10:42 PM ---------- Previous post was at 03:01 AM ----------
So, since I'm using the Venture Star as a baseline for the orbiter, and I've drastically reduced the mass ratio, I have 2 choices:
A: Shrink fuel tanks, and decrease overall vessel mass.
(Orbiter Fueled Weight: 260 tons)
B: Expand payload capability, and leave overall mass the same.
(Orbiter Fueled Weight: 991 tons, same as Venture Star)
So far, I'm choosing to go with B. After I calculate the mass of the booster (Which I'm still trying to figure out how that'll work. I think it's tied to the Impulse. J = M * Dv)
, I'll drop the mass if it's too large. But expanding the payload gives a payload mass of ~85 tons, and drastically increases the payload fraction of the vehicle. (Once again, discounting booster, since I don't know it's mass.)
But there's no garuntee the payload fraction will be much better after I add the mass of the booster, but, 85 tons is a very nice number for futuristic heavy hauls. This is a mid-near future vehicle, so 85 tons would be great for assembling space stations, or carrying modules of a Moon or Mars vehicle into orbit for on-orbit assembly. 85 tons could be enough to lift an entire moon mission, though. Or an entire small space station.
Or, most notably of all... A space hotel.
So at the moment I'm going with 85 tons, the heavier configuration. Same wet orbiter mass as Venture Star wet mass, but overall it'll be heavier because of the booster. But even if the mass doubles... That's still 2,000 tons. About the same as the STS. Not too bad.
---------- Post added 08-25-11 at 03:59 AM ---------- Previous post was 08-24-11 at 10:42 PM ----------
I just found out the SSME's are being stored for use on future vehicles as of the end of the shuttle program. Nice, reusable engines... I'm looking at those for the Dual Star. Better performance than the Venture Star's RS2200 Linear Aerospikes, apparently.
(I wonder if the 347s sea level ISP data actually comes from static tests. Because with flowing air it would be much higher, since it's the moving air that acts as a nozzle for Aerospikes. I'll read up on this some more.)
Normally I'm working on one project or another to pass time, in this case, I've ran into a fairly interesting idea...
So the Venture Star was a huge promise and a dream that ultimately failed. There are probably some folks around here that have more information on it than I do (which I would be interested in), but from what I understand the issue was technical problems with the LH2 fuel tank, because it required new materials to reach such a high mass ratio while providing the insulation and pressure containment.
So my idea was to add a booster. Okay, it wouldn't be an SSTO anymore, but:
+ The all-metal heat shield still drastically reduces turnaround time
+ A new liquid booster would have lift surfaces and a light heat shield to allow it to be fully reusable.
~The booster would be in an outline configuration, and sit on top of the Dual Star (over the payload bay, as depicted above), so that it doesn't have a chance of foam-strike on the all-metal heat shield.
+ Because the booster is fully reusable, the entire system still has all the advantages of an SSTO, without facing the issue of large mass ratio or extremes of the acceleration profile. Mating the booster to the vehicle would be trivial in comparison to the Shuttle's procedures.
The advantage of an SSTO is it's 100% reusability. That hasn't gone away. The booster in this case, if designed correctly (very heavily, that is), turnaround operations could be as easy as refilling the tanks, without major engine overhauls every flight. Because it's a booster and not the primary rocket, it can afford to be somewhat heavier, so extra mass, which means not working as near structural limits, means not such strict and comprehensive overhauls and maintenance will be required.
The Booster is a lifting body, it separates at the point where it can glide and land at the MARS (Mid-Atlantic Regional Spaceport) on [ame=http://en.wikipedia.org/wiki/Wallops_Island]Wallops Island[/ame]. This target can be reached after launching from the KSC at 42* inclination with a MECO at around ~2,500 to ~3,000 m/s.
This would restrict the missions to high-inclination orbits, but if a low inclination orbit is required, the booster could carry jet engines for a powered glide to Nova Scotia or a target on the west coast of Africa, depending on the inclination of the mission. This isn't too much of an exotic idea, the Buran spacecraft was designed to use a jet engine assisted glide, and they will only need to thrust the empty booster, which doesn't carry a large heat shield, meaning it would be extremely light.
With an ascent time of ~600 seconds, it would only need a mass ratio of 6 for the central stage. The booster will only need a Delta-Vee
I'll post more as I flesh out the idea more.
Same-day update:
Orbiter:
Delta-Vee: 7,640 m/s
Mass Ratio: 5.6767
ISP: 450 s
LOX/LH-2
Booster:
(Provides avg. 50% thrust)
Delta-Vee: 5,600 m/s
Mass Ratio: 8.275
ISP: 270 s
LOX/RP-1
Boost Delta-Vee: 1,400 m/s
Velocity at separation: 2,800 m/s
[As you'll notice, it's very easy to calculate separation velocity, boost D-v, and total D-v when the thrust is at exactly 1/2 ]
Q's:
Although Linear Aerospike nozzles are supposed to get a better ISP at every altitude, from the data provided, the SSME's actually have a better ISP than the Venture Star's RS2200 Aerospikes:
RS2200: http://www.astronautix.com/engines/rs2200.htm
SSME: http://www.astronautix.com/engines/ssme.htm
According to what I read, the Venture Star wouldn't use hypergolics. So what does it use for RCS then?
PS, if anyone noticed, the picture is of the SSTO from Ace Combat (5?).
---------- Post added at 10:42 PM ---------- Previous post was at 03:01 AM ----------
So, since I'm using the Venture Star as a baseline for the orbiter, and I've drastically reduced the mass ratio, I have 2 choices:
A: Shrink fuel tanks, and decrease overall vessel mass.
(Orbiter Fueled Weight: 260 tons)
B: Expand payload capability, and leave overall mass the same.
(Orbiter Fueled Weight: 991 tons, same as Venture Star)
So far, I'm choosing to go with B. After I calculate the mass of the booster (Which I'm still trying to figure out how that'll work. I think it's tied to the Impulse. J = M * Dv)
, I'll drop the mass if it's too large. But expanding the payload gives a payload mass of ~85 tons, and drastically increases the payload fraction of the vehicle. (Once again, discounting booster, since I don't know it's mass.)
But there's no garuntee the payload fraction will be much better after I add the mass of the booster, but, 85 tons is a very nice number for futuristic heavy hauls. This is a mid-near future vehicle, so 85 tons would be great for assembling space stations, or carrying modules of a Moon or Mars vehicle into orbit for on-orbit assembly. 85 tons could be enough to lift an entire moon mission, though. Or an entire small space station.
Or, most notably of all... A space hotel.
So at the moment I'm going with 85 tons, the heavier configuration. Same wet orbiter mass as Venture Star wet mass, but overall it'll be heavier because of the booster. But even if the mass doubles... That's still 2,000 tons. About the same as the STS. Not too bad.
---------- Post added 08-25-11 at 03:59 AM ---------- Previous post was 08-24-11 at 10:42 PM ----------
I just found out the SSME's are being stored for use on future vehicles as of the end of the shuttle program. Nice, reusable engines... I'm looking at those for the Dual Star. Better performance than the Venture Star's RS2200 Linear Aerospikes, apparently.
(I wonder if the 347s sea level ISP data actually comes from static tests. Because with flowing air it would be much higher, since it's the moving air that acts as a nozzle for Aerospikes. I'll read up on this some more.)
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