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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 |
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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. |
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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 |
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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. |
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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?
Alex Terrell wrote:
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? Alex, Thanks for the pointer to Quickreach 2. I had never heard of it before. It is interesting that they boast of the complex technology that they have managed to avoid using (complex on-the-pad abort tower system, complex pressurization and regulation system, etc.) rather than the usual boasting on how they are on the bleeding edge of technology. This gives me some hope that they might be on the right track. David Cornell |
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How big would an SSTO be?
On Jun 30, 6:03 am, Alex Terrell wrote:
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? I have been out of town. I'll respond in more detail tomorrow. As a quick answer, Quickreach should be able to launch a nearly twice as large payload a couple of years earlier than the Space Van 2011. We expect to carry 2000-kg--or eight passengers --to an ISS-type orbit (not our main mission) for a price (including ROI) of $2,000,000 per flight in 2007 dollars. This compares to a Quickreach cost (price?) of $20,000,000 in 2005 dollars. The Space Van should be able to achieve much more frequent flights, since there are no expendable parts or reusable parts that require extensive refurbishment between flights. The Space Van should have good abort options throughtout its flight regime--starting with engine-out abort capablility just after liftoff with derated engines. The engines are derated for much improved time between overhaul. As for Sylvia's request, I am not sure exactly what cycle Skylon plans to use, but I suspect that it is some type of combined-cycle engine. The poor-man's approach to analyzing combined cycle performance (except for potential benefits from saving installation space through integration) is to imagine separate rocket and airbreathing engines. The resulting thrust and specific impulse usually equals the goals for the combined cycle engine. This anaylis trick allows a quick assessment of how much airbtreathing and how much rocket the designer would like to have. If one then goes through some tradeoffs of different ratios and allows for real-trajectory estimates of drag losses and real-structure mass estimates allowing for realistic inlets and the impact of flying the whole vehicle at relatively high dynamic pressures and velocities, I have always found that the best ratio is 100 percent rocket. Many others--including highly knowledgeable people like Henry Spencer --have noted that the airbreathing appeal is rather superficial and vanishes under realistic analyses. Len |
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How big would an SSTO be?
Len wrote:
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 Len, Thank you for the informative and realistic reply. I tend to agree that a TSTO would likely be a better first step than an SSTO, but I am just an interested bystander with no experience in the field, so what do I know. I have been trying to get a picture in my mind of what a realistic near-term space craft might look like, how big it would be, how much noise it would make, what kind of maintenance and support it would require, etc. Too much of my imagination is cluttered with images of the fantasy spacecraft of sci-fi movies, in which the heroes flit around the galaxy with no regards to cost or logistics. Has anyone done any studies of the likely operational costs of recovering and reassembling the stages of a TSTO versus the savings in developmental (and perhaps operational) costs that a TSTO would have over an SSTO of similar capacity? Obviously, if going with a TSTO saved you billions in development cost and many years in development time, the fact that getting the stages back together might be an operational PIA might be a moot point. Thanks again for your insights. David Cornell |
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How big would an SSTO be?
On Jun 30, 9:31 am, David Cornell wrote:
Len wrote: 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 Len, Thank you for the informative and realistic reply. I tend to agree that a TSTO would likely be a better first step than an SSTO, but I am just an interested bystander with no experience in the field, so what do I know. I have been trying to get a picture in my mind of what a realistic near-term space craft might look like, how big it would be, how much noise it would make, what kind of maintenance and support it would require, etc. Too much of my imagination is cluttered with images of the fantasy spacecraft of sci-fi movies, in which the heroes flit around the galaxy with no regards to cost or logistics. Has anyone done any studies of the likely operational costs of recovering and reassembling the stages of a TSTO versus the savings in developmental (and perhaps operational) costs that a TSTO would have over an SSTO of similar capacity? Obviously, if going with a TSTO saved you billions in development cost and many years in development time, the fact that getting the stages back together might be an operational PIA might be a moot point. Thanks again for your insights. David Cornell- Hide quoted text - - Show quoted text - Do a search for "skylon", and then go at least 2X on it's size by adding LRBs, and roughly 3X on its GLOW mass. Should work, at less than $100 million per 100 kg passenger. Our future is going to become downright spendy, and more polluted than ever. - Brad Guth |
#10
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How big would an SSTO be?
On Jun 30, 12:31 pm, David Cornell wrote:
Len wrote: 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 Len, Thank you for the informative and realistic reply. I tend to agree that a TSTO would likely be a better first step than an SSTO, but I am just an interested bystander with no experience in the field, so what do I know. I have been trying to get a picture in my mind of what a realistic near-term space craft might look like, how big it would be, how much noise it would make, what kind of maintenance and support it would require, etc. Too much of my imagination is cluttered with images of the fantasy spacecraft of sci-fi movies, in which the heroes flit around the galaxy with no regards to cost or logistics. Has anyone done any studies of the likely operational costs of recovering and reassembling the stages of a TSTO versus the savings in developmental (and perhaps operational) costs that a TSTO would have over an SSTO of similar capacity? Obviously, if going with a TSTO saved you billions in development cost and many years in development time, the fact that getting the stages back together might be an operational PIA might be a moot point. Thanks again for your insights. David Cornell David, We haven't done a study of the "likely operational costs of recovering and reassembling the stages of a TSTO versus the savings in developmental (and perhaps operational costs) that a TSTO would have over an SSTO of similar capacity." Rather we start with no preconceived notions of this sort. Our TSTO takes of from a 3000 m (or longer) runway with the ability to either reject takeoff or continue on one derated engine immediately after liftoff from the runway. We can also abort and make a powered landing at the launch site anytime prior to staging at mach 2 at 40 km--providing orbiter propellants are jettisoned. After staging, the orbiter can jettison propellants and glide 26 km back to the launch site, if necessary. We view none of this as an "operational disadvantage" of staging. As for reassembly, a simpler version of the 747/shuttle overhead crane can lift the empty 12,500 kg orbiter onto our carrier--which does not seem to be particularly challenging. Staging eliminates propulsion altitude-compensation problems. It also allows some operational luxuries like engine-out abort at takeoff, with a powered landing with the empty orbiter on board. Finally, for our "kite plane" design approach, staging is not only straightforward and relatively easy, but it also permits the designer to address certain structural and thermal requirements separately. Many of the purported "operational advantages" of an SSTO are actually loaded questions. A lot depends upon the basic design concept. It is always possible to design a monstrosity like the Space Shuttle. No amount of testing, experience, of funding can turn a bad concept into a good concept. Len |
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