I enjoy this last post, Michel! But I still think it is kind of dubious to try to make an Orbiter that includes all the hydrogen and oxygen tankage in the Orbiter hull.
Did they ever consider this compromise--Since the Orbiter is not firing in parallel with the Booster, but afterward, what if the geometry were than the Orbiter includes the relatively dense, compact LOX tanks inside the hull, but the light and bulky hydrogen goes in a fuel tank (now really just a fuel tank and not a loose name for "propellant tank" hanging from the belly of the Orbiter? So, the Orbiter is mounted straight atop the Saturn derived winged booster, but the hydrogen tank is hanging off the belly of the Orbiter.
Just pulling the OTL numbers out of the air, which would not apply directly here of course:
OTL ET is originally some 32 tonnes, before they lightened it. It holds 726 tonnes of propellant, but only 104 of that is hydrogen, but this hydrogen fills 73 percent of the volume. Making the tank just a hydrogen tank for the same stuff, the mass I scale down by (0.73)^2/3 to reflect a conservative reduction by area only. Now it is down to 27 tonnes (and can later be lightened a bit). The overall hanging weight then is 131 tonnes--pretty close to the OTL hanging weight of the Shuttle Orbiter off the ET!
Since your Orbiter burns only as a second stage, it will need less propellant all round (well, barring the offsetting effect that encapsulating the fuel tank would raise the Orbiter dry mass by quite a bit)--it sure would if the hydrogen were kept outside anyway--so the properly figured ET would be even lighter.
You may recall that not only do I doubt that the Orbiter can be made light enough if it encloses the hydrogen tank, but that hydrogen leaking inside the fuselage is a serious risk. Putting just the hydrogen outside with the oxygen inside is better for that reason too then, the oxygen won't have the same likelihood of leaking.
So the weight can surely hang there. It is not clear to me just whether having it there would be OK for service tower reasons--so I went to your drawing to see if you have the dorsal or ventral side of the Orbiter and Booster facing the tower. You probably caught my little rants on Right Side Up against the madness of having a perfectly good escape ejection system for the Booster crew with a nice survivable capsule--then aiming it like a cannon straight at the damned service tower! I wondered which way you leaned, and if you were to listen to me then the stupid hydrogen tank would be in the way, unless it moved to the dorsal side of the Orbiter which I think would be very dumb...
...
And behold you've fixed the whole issue by mounting the stack sideways which I had not dreamed possible! Now the "upward" ejection of the Booster crew has a clear path, and yet at the same time the proposed hydrogen tank could fit just fine off to the other side! And the access to the Orbiter hatch on the side of the Orbiter, presumably on your Booster as well, faces the tower directly, no reach around as needed OTL for Shuttle. Access to both ventral and dorsal sides are quite clear! What a brilliant idea!
Why didn't NASA do this with the OTL Shuttle and have they ever had the brains to think of doing this themselves?
OK i can see that the SRBs would have made having one of them right next to the bottom of the tower structure pretty problematic, which is why not do it with TAOS Shuttle.
Yet another blow for the rationality of Saturn Shuttle!
Does the flight crew of the Booster have an escape capsule as in Right Side Up, or do they have ejection seats only (boo!). I think a capsule that itself has ejection seats is needed, for an exciting two ejections. Sometimes the capsule will come down soft and crew should stay in it, because it floats and is protection from the environment--heat, cold, sharks, alligators, mosquitoes... and can have a lot of good survival gear in it, first aid kits and flare guns and all that jazz. But sometimes the capsule is going to come down hard or wrong or needs to be destroyed by the range officer because it is going to hit a shopping mall or something, and then the crew need to eject from the capsule. But only ever after riding the ejected capsule out first--they need protection from blast and other hazards while ejecting.
Your drawings are gorgeous as always Michel. But I can't see any control cabin on the Booster. it looks like it would be right under the Orbiter tail--oh now I see it. Shouldn't it be smaller than the OTL Orbiter one since we just have a couple astronaut pilots in it, no need for all the cabin space an Orbiter would need?
Did they ever consider this compromise--Since the Orbiter is not firing in parallel with the Booster, but afterward, what if the geometry were than the Orbiter includes the relatively dense, compact LOX tanks inside the hull, but the light and bulky hydrogen goes in a fuel tank (now really just a fuel tank and not a loose name for "propellant tank" hanging from the belly of the Orbiter? So, the Orbiter is mounted straight atop the Saturn derived winged booster, but the hydrogen tank is hanging off the belly of the Orbiter.
Just pulling the OTL numbers out of the air, which would not apply directly here of course:
OTL ET is originally some 32 tonnes, before they lightened it. It holds 726 tonnes of propellant, but only 104 of that is hydrogen, but this hydrogen fills 73 percent of the volume. Making the tank just a hydrogen tank for the same stuff, the mass I scale down by (0.73)^2/3 to reflect a conservative reduction by area only. Now it is down to 27 tonnes (and can later be lightened a bit). The overall hanging weight then is 131 tonnes--pretty close to the OTL hanging weight of the Shuttle Orbiter off the ET!
Since your Orbiter burns only as a second stage, it will need less propellant all round (well, barring the offsetting effect that encapsulating the fuel tank would raise the Orbiter dry mass by quite a bit)--it sure would if the hydrogen were kept outside anyway--so the properly figured ET would be even lighter.
You may recall that not only do I doubt that the Orbiter can be made light enough if it encloses the hydrogen tank, but that hydrogen leaking inside the fuselage is a serious risk. Putting just the hydrogen outside with the oxygen inside is better for that reason too then, the oxygen won't have the same likelihood of leaking.
So the weight can surely hang there. It is not clear to me just whether having it there would be OK for service tower reasons--so I went to your drawing to see if you have the dorsal or ventral side of the Orbiter and Booster facing the tower. You probably caught my little rants on Right Side Up against the madness of having a perfectly good escape ejection system for the Booster crew with a nice survivable capsule--then aiming it like a cannon straight at the damned service tower! I wondered which way you leaned, and if you were to listen to me then the stupid hydrogen tank would be in the way, unless it moved to the dorsal side of the Orbiter which I think would be very dumb...
...
And behold you've fixed the whole issue by mounting the stack sideways which I had not dreamed possible! Now the "upward" ejection of the Booster crew has a clear path, and yet at the same time the proposed hydrogen tank could fit just fine off to the other side! And the access to the Orbiter hatch on the side of the Orbiter, presumably on your Booster as well, faces the tower directly, no reach around as needed OTL for Shuttle. Access to both ventral and dorsal sides are quite clear! What a brilliant idea!
Why didn't NASA do this with the OTL Shuttle and have they ever had the brains to think of doing this themselves?
OK i can see that the SRBs would have made having one of them right next to the bottom of the tower structure pretty problematic, which is why not do it with TAOS Shuttle.
Yet another blow for the rationality of Saturn Shuttle!
Does the flight crew of the Booster have an escape capsule as in Right Side Up, or do they have ejection seats only (boo!). I think a capsule that itself has ejection seats is needed, for an exciting two ejections. Sometimes the capsule will come down soft and crew should stay in it, because it floats and is protection from the environment--heat, cold, sharks, alligators, mosquitoes... and can have a lot of good survival gear in it, first aid kits and flare guns and all that jazz. But sometimes the capsule is going to come down hard or wrong or needs to be destroyed by the range officer because it is going to hit a shopping mall or something, and then the crew need to eject from the capsule. But only ever after riding the ejected capsule out first--they need protection from blast and other hazards while ejecting.
Your drawings are gorgeous as always Michel. But I can't see any control cabin on the Booster. it looks like it would be right under the Orbiter tail--oh now I see it. Shouldn't it be smaller than the OTL Orbiter one since we just have a couple astronaut pilots in it, no need for all the cabin space an Orbiter would need?
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