Eagle1Division
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So, I'm being a bit rash to post this so quickly after I came up with the idea, but It's really neat...
The idea is to replace the 3 SSME's with Nuclear Thermal Rockets. The objective is that this new nuclear shuttle should be able to either go to the Moon or Mars.
To facilitate the lower thrust, and the fact the ET would be heavy through the entire ascent, lowering the shuttle's acceleration even further, either larger (such as the 5-segment) SRB's would be added, or even LRB's to provide a much larger high-thrust boost Delta-Vee.
(Perhaps the first stages of some other rockets?)
I doubt the NTR's will provide enough thrust power for taking off from Mars, and the shuttle's External tank would have to be attached the whole time, so the idea would be to put an excersion and ascent module in the payload bay, along with some packages to extend the shuttle's duration.
Interestingly enough, the Apollo LM would comfortably fit in the shuttle's payload bay with plenty of room to spare.
Apollo LM:
14x13.3x17.9 ft (width x depth x height)
14,696 kg
Payload bay:
15x60 ft (diameter x height)
25,060 kg (May drastically increase with NTR engines)
I've run by the math using different types of propellant, LH2 is too thin, so using the existing ET I got a mass ratio far too small, and Ammonia doesn't have enough Isp, the highest Delta-Vee came from using CH4, Methane.
Liquid Methane is much warmer than LOX, especially LH2, so less insulation would be required, but it's heavier weight means more structure mass. I'll assume the two roughly cancel.
Filling the LOX and LH2 volume of the ET with Methane...
(Discluding SRB's)
Mass Ratio: 7.27
Exhaust Velocity: 6,318 m/s (NTR Solid Ch4)
Delta-Vee: 12,535 m/s
Compare the original Space shuttle (also disculding SRB's)
Mass Ratio: 6.42
Exhaust Velocity: 4,142 m/s (Two-thirds Vacuum ISP over SL ISP)
Delta-Vee: 7,704 m/s
So the NTR design gives an extra 4,830 m/s of Delta-Vee. I'm also planning to use the first stage of some other liquid-fuelled rocket to replace the SRB's, which will add even more Delta-Vee.
That's enough for now, I'll get back to this tomorrow, so here's the work order:
First:
SRB Replacement
Requirements:
~13.5 MN of thrust (I can add more engines to get this)
-Delta-Vee greater than 4,795 m/s (current SRB Delta-Vee)
-Must be an existing rocket first stage.
(I'll try the Falcon 9 and Delta-IV first stages. Those are roughly the same size as the SRB's and are capable of being used as boosters.)
Second:
Possible Mission:
Is a lunar mission possible with this much Delta-Vee? How about a mars mission? A hopeful reminder is that the lander will be in the payload bay, and that a Lunar lander can easily do this with plenty of room and weight to spare. A Mars lander is a different story, though! Can I get a Mars lander to fit in a 15x60 payload bay?...
(Note Mars has 8.7x lunar mass and 2.3x lunar gravity, though, unlike the moon, aerobrake will be possible, very small Delta-Vee needed to land.)
A hopeful reminder is that the figures I worked above - where the shuttle minus the SRB's has 12,535 m/s of Delta-Vee, include a full payload bay. Once the mission is done, the orbiter+ET will be 25 tons lighter, since the lander could be left behind.
(But, if it's possible to bring the inert lander home, then that would be wonderful! Fully Re-usable Mars or Moon mission! How's that!?)
[PS, I intend to make this an add-on, but I've seen similar things titled as discussion. I want some back and forth discussion here, so I'll leave the title as that...]
The idea is to replace the 3 SSME's with Nuclear Thermal Rockets. The objective is that this new nuclear shuttle should be able to either go to the Moon or Mars.
To facilitate the lower thrust, and the fact the ET would be heavy through the entire ascent, lowering the shuttle's acceleration even further, either larger (such as the 5-segment) SRB's would be added, or even LRB's to provide a much larger high-thrust boost Delta-Vee.
(Perhaps the first stages of some other rockets?)
I doubt the NTR's will provide enough thrust power for taking off from Mars, and the shuttle's External tank would have to be attached the whole time, so the idea would be to put an excersion and ascent module in the payload bay, along with some packages to extend the shuttle's duration.
Interestingly enough, the Apollo LM would comfortably fit in the shuttle's payload bay with plenty of room to spare.
Apollo LM:
14x13.3x17.9 ft (width x depth x height)
14,696 kg
Payload bay:
15x60 ft (diameter x height)
25,060 kg (May drastically increase with NTR engines)
I've run by the math using different types of propellant, LH2 is too thin, so using the existing ET I got a mass ratio far too small, and Ammonia doesn't have enough Isp, the highest Delta-Vee came from using CH4, Methane.
Liquid Methane is much warmer than LOX, especially LH2, so less insulation would be required, but it's heavier weight means more structure mass. I'll assume the two roughly cancel.
Filling the LOX and LH2 volume of the ET with Methane...
(Discluding SRB's)
Mass Ratio: 7.27
Exhaust Velocity: 6,318 m/s (NTR Solid Ch4)
Delta-Vee: 12,535 m/s
Compare the original Space shuttle (also disculding SRB's)
Mass Ratio: 6.42
Exhaust Velocity: 4,142 m/s (Two-thirds Vacuum ISP over SL ISP)
Delta-Vee: 7,704 m/s
So the NTR design gives an extra 4,830 m/s of Delta-Vee. I'm also planning to use the first stage of some other liquid-fuelled rocket to replace the SRB's, which will add even more Delta-Vee.
That's enough for now, I'll get back to this tomorrow, so here's the work order:
First:
SRB Replacement
Requirements:
~13.5 MN of thrust (I can add more engines to get this)
-Delta-Vee greater than 4,795 m/s (current SRB Delta-Vee)
-Must be an existing rocket first stage.
(I'll try the Falcon 9 and Delta-IV first stages. Those are roughly the same size as the SRB's and are capable of being used as boosters.)
Second:
Possible Mission:
Is a lunar mission possible with this much Delta-Vee? How about a mars mission? A hopeful reminder is that the lander will be in the payload bay, and that a Lunar lander can easily do this with plenty of room and weight to spare. A Mars lander is a different story, though! Can I get a Mars lander to fit in a 15x60 payload bay?...
(Note Mars has 8.7x lunar mass and 2.3x lunar gravity, though, unlike the moon, aerobrake will be possible, very small Delta-Vee needed to land.)
A hopeful reminder is that the figures I worked above - where the shuttle minus the SRB's has 12,535 m/s of Delta-Vee, include a full payload bay. Once the mission is done, the orbiter+ET will be 25 tons lighter, since the lander could be left behind.
(But, if it's possible to bring the inert lander home, then that would be wonderful! Fully Re-usable Mars or Moon mission! How's that!?)
[PS, I intend to make this an add-on, but I've seen similar things titled as discussion. I want some back and forth discussion here, so I'll leave the title as that...]
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