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How big would an SSTO be?



 
 
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  #1  
Old June 29th 07, 05:25 PM posted to sci.space.policy
David Cornell
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Posts: 9
Default 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  
Old June 29th 07, 11:55 PM posted to sci.space.policy
Sylvia Else
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Posts: 1,063
Default 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  
Old June 30th 07, 03:38 AM posted to sci.space.policy
Len[_2_]
external usenet poster
 
Posts: 427
Default 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  
Old June 30th 07, 04:38 AM posted to sci.space.policy
Sylvia Else
external usenet poster
 
Posts: 1,063
Default 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  
Old June 30th 07, 11:03 AM posted to sci.space.policy
Alex Terrell
external usenet poster
 
Posts: 492
Default 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  
Old June 30th 07, 11:32 AM posted to sci.space.policy
Ian Parker
external usenet poster
 
Posts: 2,554
Default 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  
Old June 30th 07, 11:37 AM posted to sci.space.policy
Ian Parker
external usenet poster
 
Posts: 2,554
Default 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  
Old June 30th 07, 12:56 PM posted to sci.space.policy
Sylvia Else
external usenet poster
 
Posts: 1,063
Default 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  
Old June 30th 07, 01:29 PM posted to sci.space.policy
Sylvia Else
external usenet poster
 
Posts: 1,063
Default 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  
Old June 30th 07, 03:40 PM posted to sci.space.policy
Ian Parker
external usenet poster
 
Posts: 2,554
Default 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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