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#1
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How big would an SSTO be?
If someone were to build an SSTO using realistic assumptions about mass
ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell |
#2
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How big would an SSTO be?
David Cornell wrote:
If someone were to build an SSTO using realistic assumptions about mass ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell You didn't say so, but I'm assuming you mean a reusable craft. Disposable SSTO's seem a waste of effort. The most developed design I've seen for a reusable SSTO is http://www.reactionengines.co.uk/skylon_vehicle.html It has a payload of 12 tonnes, and a maximum takeoff weight around 280 tonnes, similar to that of a 777-300. It uses a new engine design with some technological challenges, but they seem to have made some progress with it. They're obviously financially constrained, so if you have a spare $billion, I'm sure they be interested in talking. Skylon is an automated system, and as such is not designed to have a crew, but could carry people as payload. This document http://www.reactionengines.co.uk/dow...56_118-126.pdf discusses that application using a module carrying 40 people, though that's obviously in a transport application (to a space hotel, perhaps). If you have space tourism in mind, with passengers not leaving the craft and floating around the cabin, then presumably they'd need more space per passenger. It's hard to say how this scales for a smaller payload, but at a guess, I'd say you could get a craft to carry four people that was the size of a small airliner in the 50 seat range. Sylvia. |
#3
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How big would an SSTO be?
On Jun 29, 6:55 pm, Sylvia Else wrote:
David Cornell wrote: If someone were to build an SSTO using realistic assumptions about mass ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell You didn't say so, but I'm assuming you mean a reusable craft. Disposable SSTO's seem a waste of effort. The most developed design I've seen for a reusable SSTO is http://www.reactionengines.co.uk/skylon_vehicle.html It has a payload of 12 tonnes, and a maximum takeoff weight around 280 tonnes, similar to that of a 777-300. It uses a new engine design with some technological challenges, but they seem to have made some progress with it. They're obviously financially constrained, so if you have a spare $billion, I'm sure they be interested in talking. Skylon is an automated system, and as such is not designed to have a crew, but could carry people as payload. This document http://www.reactionengines.co.uk/dow...56_118-126.pdf discusses that application using a module carrying 40 people, though that's obviously in a transport application (to a space hotel, perhaps). If you have space tourism in mind, with passengers not leaving the craft and floating around the cabin, then presumably they'd need more space per passenger. It's hard to say how this scales for a smaller payload, but at a guess, I'd say you could get a craft to carry four people that was the size of a small airliner in the 50 seat range. Sylvia. I have probably looked at as many launch vehicle concepts --rocket powered and airbreathers--as anybody in the world. The devil is in the details. I would not consider Skylon anywhere close to realistic. As for purely rocket-powered approaches, I have never been able to convince myself that any SSTO having a gross mass of less than about 800 tonnes was very realistic. And for HTOL, some type of ground cart to support the vehicle at gross mass is probably necessary--thus making it really an assisted SSTO, rather than a pure SSTO. Staging--even subsonically at altitude or at low supersonic speeds greatly relieves the challenge. IMO, staging can sometimes be beneficial from the operations point of view--as wsll as the performance point of view. SSTOs are undoubtedly appealing from the psychological point of view. However, they may not be a good way to run an airline. At some combination of size and yet-to-be-discovered technology, SSTOs will make technical, economic and marketing sense; but I don't see this happening soon. Len |
#4
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How big would an SSTO be?
Len wrote:
On Jun 29, 6:55 pm, Sylvia Else wrote: David Cornell wrote: If someone were to build an SSTO using realistic assumptions about mass ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell You didn't say so, but I'm assuming you mean a reusable craft. Disposable SSTO's seem a waste of effort. The most developed design I've seen for a reusable SSTO is http://www.reactionengines.co.uk/skylon_vehicle.html It has a payload of 12 tonnes, and a maximum takeoff weight around 280 tonnes, similar to that of a 777-300. It uses a new engine design with some technological challenges, but they seem to have made some progress with it. They're obviously financially constrained, so if you have a spare $billion, I'm sure they be interested in talking. Skylon is an automated system, and as such is not designed to have a crew, but could carry people as payload. This document http://www.reactionengines.co.uk/dow...56_118-126.pdf discusses that application using a module carrying 40 people, though that's obviously in a transport application (to a space hotel, perhaps). If you have space tourism in mind, with passengers not leaving the craft and floating around the cabin, then presumably they'd need more space per passenger. It's hard to say how this scales for a smaller payload, but at a guess, I'd say you could get a craft to carry four people that was the size of a small airliner in the 50 seat range. Sylvia. I have probably looked at as many launch vehicle concepts --rocket powered and airbreathers--as anybody in the world. The devil is in the details. I would not consider Skylon anywhere close to realistic. As for purely rocket-powered approaches, I have never been able to convince myself that any SSTO having a gross mass of less than about 800 tonnes was very realistic. And for HTOL, some type of ground cart to support the vehicle at gross mass is probably necessary--thus making it really an assisted SSTO, rather than a pure SSTO. Staging--even subsonically at altitude or at low supersonic speeds greatly relieves the challenge. IMO, staging can sometimes be beneficial from the operations point of view--as wsll as the performance point of view. SSTOs are undoubtedly appealing from the psychological point of view. However, they may not be a good way to run an airline. At some combination of size and yet-to-be-discovered technology, SSTOs will make technical, economic and marketing sense; but I don't see this happening soon. Len Would you care to expand on your concerns. At the moment, you've basically said that you're an expert and that we should believe your claim that Skylon is not realistic. Sylvia. |
#5
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How big would an SSTO be?
On 30 Jun, 04:38, Sylvia Else wrote:
Len wrote: On Jun 29, 6:55 pm, Sylvia Else wrote: David Cornell wrote: If someone were to build an SSTO using realistic assumptions about mass ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell You didn't say so, but I'm assuming you mean a reusable craft. Disposable SSTO's seem a waste of effort. The most developed design I've seen for a reusable SSTO is http://www.reactionengines.co.uk/skylon_vehicle.html It has a payload of 12 tonnes, and a maximum takeoff weight around 280 tonnes, similar to that of a 777-300. It uses a new engine design with some technological challenges, but they seem to have made some progress with it. They're obviously financially constrained, so if you have a spare $billion, I'm sure they be interested in talking. Skylon is an automated system, and as such is not designed to have a crew, but could carry people as payload. This document http://www.reactionengines.co.uk/dow...56_118-126.pdf discusses that application using a module carrying 40 people, though that's obviously in a transport application (to a space hotel, perhaps). If you have space tourism in mind, with passengers not leaving the craft and floating around the cabin, then presumably they'd need more space per passenger. It's hard to say how this scales for a smaller payload, but at a guess, I'd say you could get a craft to carry four people that was the size of a small airliner in the 50 seat range. Sylvia. I have probably looked at as many launch vehicle concepts --rocket powered and airbreathers--as anybody in the world. The devil is in the details. I would not consider Skylon anywhere close to realistic. As for purely rocket-powered approaches, I have never been able to convince myself that any SSTO having a gross mass of less than about 800 tonnes was very realistic. And for HTOL, some type of ground cart to support the vehicle at gross mass is probably necessary--thus making it really an assisted SSTO, rather than a pure SSTO. Staging--even subsonically at altitude or at low supersonic speeds greatly relieves the challenge. IMO, staging can sometimes be beneficial from the operations point of view--as wsll as the performance point of view. SSTOs are undoubtedly appealing from the psychological point of view. However, they may not be a good way to run an airline. At some combination of size and yet-to-be-discovered technology, SSTOs will make technical, economic and marketing sense; but I don't see this happening soon. Len Would you care to expand on your concerns. At the moment, you've basically said that you're an expert and that we should believe your claim that Skylon is not realistic. Sylvia. I believe Len is an expert and would take his word for it. Nevertheless, an expansion on the concerns would be of interest. However, I don't see the benefit in SSTO when concepts like Quickreach 2 (http://www.astronautix.com/lvs/quieach2.htm) could reach orbit for relatively low cost. Len - how does Quickreach 2 compare to the latest space van proposals? |
#6
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How big would an SSTO be?
On 29 Jun, 23:55, Sylvia Else wrote:
David Cornell wrote: If someone were to build an SSTO using realistic assumptions about mass ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell You didn't say so, but I'm assuming you mean a reusable craft. Disposable SSTO's seem a waste of effort. The most developed design I've seen for a reusable SSTO is http://www.reactionengines.co.uk/skylon_vehicle.html It has a payload of 12 tonnes, and a maximum takeoff weight around 280 tonnes, similar to that of a 777-300. It uses a new engine design with some technological challenges, but they seem to have made some progress with it. They're obviously financially constrained, so if you have a spare $billion, I'm sure they be interested in talking. Skylon is an automated system, and as such is not designed to have a crew, but could carry people as payload. This document http://www.reactionengines.co.uk/dow...56_118-126.pdf discusses that application using a module carrying 40 people, though that's obviously in a transport application (to a space hotel, perhaps). If you have space tourism in mind, with passengers not leaving the craft and floating around the cabin, then presumably they'd need more space per passenger. It's hard to say how this scales for a smaller payload, but at a guess, I'd say you could get a craft to carry four people that was the size of a small airliner in the 50 seat range. There is one significant engineering fact that nobody seems to be clear about and that is scaling. Suppose you double the size of something. The weight and hence the stresses go up 8 fold whilst the structural strength (cross sectional area) only goes up 4 times. Same thing is true of reentry heat 8 times the heat, only 4 times the airframe area. I would like to see a hpersonic profile (missing in the paper) showing exactly what the stresses are, both structural and thermal. Some time ago I think it was Alex Terrell who initiated a discussion on the Moon base. We got down to the question of competitions. Someone suggested maintaining a car with a 2.5 sec time lag built in to simulate a signal going back and forth from the Moon to Earth. Good idea! I suggest extending this principle. NASA has got some marvellous aerodynamic simulation software. What I suggest is that we build, usig a CAD system a hypersonic plane, or indeed any other SSTO configuration. Let us see what the problems with it are. Does it fall apart before it gets to LEO? OK simulation is not perfect but we will at least sort out the utterly hopeless. I think that NASA should negotiate with its software providers on license issues and organize a competition, no design barred until it is proved not to work. Quite clearly in the absence of aerdynamic and structural data we are no furter forward. There may be but I have not seen it. What is a hypersonic aircraft made out of? How hot does it get? There may be answers somewhere - not in the reference. - Ian Parker |
#7
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How big would an SSTO be?
Skylon has some of these details - fiber reinforced ceramic. Loads
purely aerodynamic. This design has I understand been around for some time. There must be snags somewhere otherwise NASA would have adopted it. Also if you were to take only one astronaut up at a time the materials science questions would be that little bit less severe. - Ian Parker |
#8
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How big would an SSTO be?
Ian Parker wrote:
Skylon has some of these details - fiber reinforced ceramic. Loads purely aerodynamic. This design has I understand been around for some time. There must be snags somewhere otherwise NASA would have adopted it. The main snag in that regard would be that it wasn't invented in America. Sylvia. |
#9
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How big would an SSTO be?
Ian Parker wrote:
On 29 Jun, 23:55, Sylvia Else wrote: David Cornell wrote: If someone were to build an SSTO using realistic assumptions about mass ratios and available power systems, how big a vehicle would be needed to send (say) three people and a modest amount of cargo into LEO? I have seen Apollo capsules in museums, so I am using them as my baseline. Would such a thing be the size of a regular jetliner? Or the new Airbus super jumbo jet? Or are we talking about a Zeppelin on steroids? Also, how would these things scale? If we wanted to increase the crew from three to four, would the vehicle size go up by a third? Or more? Thanks David Cornell You didn't say so, but I'm assuming you mean a reusable craft. Disposable SSTO's seem a waste of effort. The most developed design I've seen for a reusable SSTO is http://www.reactionengines.co.uk/skylon_vehicle.html It has a payload of 12 tonnes, and a maximum takeoff weight around 280 tonnes, similar to that of a 777-300. It uses a new engine design with some technological challenges, but they seem to have made some progress with it. They're obviously financially constrained, so if you have a spare $billion, I'm sure they be interested in talking. Skylon is an automated system, and as such is not designed to have a crew, but could carry people as payload. This document http://www.reactionengines.co.uk/dow...56_118-126.pdf discusses that application using a module carrying 40 people, though that's obviously in a transport application (to a space hotel, perhaps). If you have space tourism in mind, with passengers not leaving the craft and floating around the cabin, then presumably they'd need more space per passenger. It's hard to say how this scales for a smaller payload, but at a guess, I'd say you could get a craft to carry four people that was the size of a small airliner in the 50 seat range. There is one significant engineering fact that nobody seems to be clear about and that is scaling. Suppose you double the size of something. The weight and hence the stresses go up 8 fold whilst the structural strength (cross sectional area) only goes up 4 times. Same thing is true of reentry heat 8 times the heat, only 4 times the airframe area. This is a problem when the structural strength is required to support the structure. In something like an SSTO, most of the takeoff weight is in the fuel, so the structural strength is mostly required to support the fuel. The scaling behaviour won't be anything like as severe. Similarly, you don't get such a huge benefit from reducing payload. I would like to see a hpersonic profile (missing in the paper) showing exactly what the stresses are, both structural and thermal. Some time ago I think it was Alex Terrell who initiated a discussion on the Moon base. We got down to the question of competitions. Someone suggested maintaining a car with a 2.5 sec time lag built in to simulate a signal going back and forth from the Moon to Earth. Good idea! I suggest extending this principle. NASA has got some marvellous aerodynamic simulation software. What I suggest is that we build, usig a CAD system a hypersonic plane, or indeed any other SSTO configuration. Let us see what the problems with it are. Does it fall apart before it gets to LEO? OK simulation is not perfect but we will at least sort out the utterly hopeless. I think that NASA should negotiate with its software providers on license issues and organize a competition, no design barred until it is proved not to work. Quite clearly in the absence of aerdynamic and structural data we are no furter forward. There may be but I have not seen it. What is a hypersonic aircraft made out of? How hot does it get? There may be answers somewhere - not in the reference. There's detail in some of the other papers. See for example http://www.reactionengines.co.uk/dow...IS_v57_x-x.pdf Sylvia. |
#10
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How big would an SSTO be?
On 30 Jun, 12:56, Sylvia Else wrote:
Ian Parker wrote: Skylon has some of these details - fiber reinforced ceramic. Loads purely aerodynamic. This design has I understand been around for some time. There must be snags somewhere otherwise NASA would have adopted it. The main snag in that regard would be that it wasn't invented in America. Sylvia. Interesting! I have been promoting the Adam Smith launcher. This, essentially, is putting payloads into space by the cheapest method regardless of technology of flag. In point of fact if you used Soyuz, Proton, Long March you would save a lot of money. OK you will say, a lot of the difference is wage costs. Well this isn't taken into account anywhere else. If we see a pair of shoes we like we don't ask for the real cost in man hours. Similarly for cars. We pay $15,000 say, for a car and simply ask "What is its performance? how long is its warrantry?" No, no - An American car must be buily using the latest labor saving technology to be competitive. We don't buy a Ford Shuttle at $200,000 simply because it is American. I have just asked the $64 billion dollar question. To what extent is space nationalistic. I think I made my views on nationalism both in space, and generally, abundantly clear. The fact I have had the stick I have had indicates something. To get back to as hypersonic plane. I feel that the concept of the Adam Smith launcher mandates people putting their shirt on a particular concept. Could I persuade people to put their shirt on a hypersonic plane? Quite possibly, but a SMALL plane, 2 astronauts max. One last remark about Concorde and supersonic aviation. The money is now on an executive NOT an airliner. We could have one hypersonic variant which was an LEO launcher and another that was a long range executive. One imperative - a small launcher must operate WITHOUT a pilot. - Ian Parker |
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