Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 442676 times)

Online Stormbringer

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1240 on: 02/08/2016 02:25 PM »
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*



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Offline Hanelyp

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1241 on: 02/08/2016 04:24 PM »
Killing a satellite doesn't require the kill device to reach orbit.  It's enough for the device to be in the right spot for the satellite to hit it.

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1242 on: 02/08/2016 04:41 PM »
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Online t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1243 on: 02/08/2016 06:18 PM »
Responding generally to the idea of ASAT, I would have thought Skylon/whatever is far more appropriate to the opposite side of the equation - replacing satellites that have been knocked out.

One might imagine that putting satellites in space purely for a contingency costs money and allows them to become obsolete and allows an enemy to study them and try to intercept their communications.  So you could leave your war-winning system in a mountain somewhere, continually improving it  and launch it only at need - if you could do it fairly rapidly.   What would be? An ASAT defence system? A surge in the number of satellites for some observation system that is already in orbit giving it much higher resolution?   Star wars mk2? Something anyhow that you could hide from your foes and surprise them with.

Offline adrianwyard

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1244 on: 02/08/2016 06:39 PM »
It's an interesting question: would affordable launch (if enabled by Skylon and others) make ASAT development less attractive because assets can be easily replaced, or more likely because space-based weapons can be launched on smaller budgets... That question probably deserves a new thread, though.

Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1245 on: 02/08/2016 11:20 PM »
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1246 on: 02/09/2016 08:38 AM »
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html

I am aware, but sending a laser to cut through the deep planet atmosphere does not sound very efficient. A Skylong-based system instead would be able to reach low orbit, disable the target satellite with much larger laser efficiency, and turn back.

It's an interesting question: would affordable launch (if enabled by Skylon and others) make ASAT development less attractive because assets can be easily replaced, or more likely because space-based weapons can be launched on smaller budgets... That question probably deserves a new thread, though.

I agree it deserves a new topic, although Skylon is related. However, so far, only a country is seriously developing reusable launchers, so it is not yet worth discussing strategically...

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1247 on: 02/09/2016 07:52 PM »
I have been thinknig, of late, at a different military application for a Sabre-based vehicle. Let's say, a small-ish drone carrying anti-sat weaponry which jumps to LEO, releases its small payload, and goes back. How small can a sabre-based vehicle be made? I am sure there is a downard limitation...
It depends.

The joker in the pack is the chamber pressure.  The physical properties of LH2 make building small high pressure LH2 pumps very difficult. During talks about their ground based test engine planned to go with pressure feeding as designing such a pump would take up most (if not all) of their planned budget.

I'm still hoping the do a full size (but not flight weight) engine.
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Offline Dalhousie

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1248 on: 02/09/2016 11:50 PM »

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html

Poorly supported speculation a 5-10 years old that probably is not relevant here.
« Last Edit: 02/09/2016 11:52 PM by Dalhousie »
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Offline knowles2

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1249 on: 02/13/2016 12:24 PM »
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html
Quote
I am aware, but sending a laser to cut through the deep planet atmosphere does not sound very efficient. A Skylong-based system instead would be able to reach low orbit, disable the target satellite with much larger laser efficiency, and turn back.
These systems aren't designed to permanently disable satellites, just to blind them and prevent them taking clear pictures of what going on on the ground.

Space base weapons is vastly more costly, why achieving the same thing as ground base lasers, blinding your opponents to your activities. Plus you less likely to trigger international incident if you just blinding a satellite instead of shooting it down.
« Last Edit: 02/15/2016 12:01 AM by knowles2 »

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1250 on: 02/16/2016 10:40 AM »
The problem with that as I see it is we already have ASAT capability even from something as small as conventional fighter jets, big bombers, and naval destroyers. developing a sabre derivative for the same thing wouldn't at first glance seem logical.

*shakes REL box to encourage faster news delivery*

true. But most of these methods are devastating in terms of space environment. Maybe blinding lasers would be more effective than from the ground?

Just speculating of course.

Iran and China have been blinding US satellites for years using lasers.

http://www.ynetnews.com/articles/0,7340,L-4162770,00.html

http://www.telegraph.co.uk/news/worldnews/1529864/Beijing-secretly-fires-lasers-to-disable-US-satellites.html
Quote
I am aware, but sending a laser to cut through the deep planet atmosphere does not sound very efficient. A Skylong-based system instead would be able to reach low orbit, disable the target satellite with much larger laser efficiency, and turn back.
These systems aren't designed to permanently disable satellites, just to blind them and prevent them taking clear pictures of what going on on the ground.

Space base weapons is vastly more costly, why achieving the same thing as ground base lasers, blinding your opponents to your activities. Plus you less likely to trigger international incident if you just blinding a satellite instead of shooting it down.

yes, but the "mission profile" is not a peacetime attempt to decrease a competitor's capacities without provoking international unease.
Rather, it is becoming clear that any large scale conflict of the future will be  chacraterised by attempts to achieve space dominance first. having a reliable, quick and cheap launcher, copuled with a modified version capable of taking down the opponent's assets, is a game changer in that scenario.

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1251 on: 02/20/2016 03:40 PM »
The lack of news is making me feel a bit grim, being a news junkie.

I read that there's a talk at the University of Nottingham by Mark Thomas on 15 March at 5:30 pm.   I'm posting this in the hope that someone will be able to go as it looks like there's no chance of me being able to do it.

http://www.tinyurl.com/SABRElecture

The University of Nottingham - Engineering & Science Learning Centre (ESLC), B01. University Park. Nottingham NG7 2RD GB

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1252 on: 02/21/2016 05:21 PM »
I just realised that I forgot a list of questions.  Perhaps we should suggest some in case someone has a chance to ask them?

For me:

1) What's the response to the recent economic analysis from Ashley Dove-Jay at Bristol University that cast an unfavourable light on Skylon's economics? I'm not trying to be aggressive about this because it's obvious that everything depends on a set of assumptions. I just want to know what REL thinks.

2) The other thing I want to ask is if they feel like commenting on the issue raised by NASA Ames about the temperature at the tail.








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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1253 on: 02/23/2016 04:41 PM »
Hey guess what, guys and girls??? I just discovered an astounding thing. ** this thread is NOT about SpaceX **

Trimmed.

Posts sent to sleep with the fishes.
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Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1254 on: 02/25/2016 02:46 PM »
yes, but the "mission profile" is not a peacetime attempt to decrease a competitor's capacities without provoking international unease.
Rather, it is becoming clear that any large scale conflict of the future will be  chacraterised by attempts to achieve space dominance first. having a reliable, quick and cheap launcher, copuled with a modified version capable of taking down the opponent's assets, is a game changer in that scenario.
The subject is referred to as "Responsive space" by the USAF and they have organized several conferences on it. AFAIK the proceedings are online.

One of the things you discover when you study this subject is that reusability is not enough

The vehicle must be able to launch on a consistent basis IE a regular "service" should be possible.

Likewise customers must know that their payload will not be dropped off the manifest for no reason they can control. This was one of the frustrations with (IIRC) McDonald Douglas's work on protein separation. It was only (IIRC) a couple of mid deck lockers but was one of the few serious efforts to do commercial research in space for short term payback. It kept getting put back. This is death to any sort of development schedule.

Please keep in mind REL reckon a 2 day turnaround is possible but its payload is 15 tonnes to LEO, whereas a Delta IV Heavy is looking at 24 tonnes. It would simply not be able to replace some of the bigger NRO payloads. Wheather you need all that mass, or could split the payload into multiple single instrument satellites under 15 tonnes (or 6 tonnes with the SUS to get them to GTO) is another question.

I would also note a laser killer satellite can be launched just as easily by an ELV and if left attached to Skylon would have a life on orbit of about 4-6 days, because Skylon is expected to deliver stuff to orbit then return, a process taking about a day for return to the original launch site, but rather less if people are OK with it landing, picking up LH2 and self ferrying back to base.
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Offline Til800?CU

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1255 on: 02/26/2016 11:02 PM »
I am curious is not the laser approach superseding "engine" tech so should not efforts be thinking on coming up for better ideas in that line of direction?  ::)
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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1256 on: 02/26/2016 11:49 PM »
Rockets for lift-off take on the order of Gigawatts of power. This is why laser launch isn't terribly practical except for very small rockets, which still would need many megawatts.

People often underestimate just how much power is involved with modern rockets. Falcon Heavy, for instance, would produce on the order of 60 Gigawatts. BFR would be 200-300 Gigawatts, i.e. half the average US electric grid output.
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Offline Til800?CU

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1257 on: 02/27/2016 02:25 AM »
Rockets for lift-off take on the order of Gigawatts of power. This is why laser launch isn't terribly practical except for very small rockets, which still would need many megawatts.

People often underestimate just how much power is involved with modern rockets. Falcon Heavy, for instance, would produce on the order of 60 Gigawatts. BFR would be 200-300 Gigawatts, i.e. half the average US electric grid output.

Indeed I was thinking more "in space" not lift off ;)
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Offline R7

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1258 on: 02/27/2016 11:41 AM »
<lasers>

Indeed I was thinking more "in space" not lift off ;)

Laser in space propulsion does not belong to Skylon thread. Photonic propulsion thread is more suitable.
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Offline Til800?CU

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1259 on: 02/27/2016 09:01 PM »
I was just sayin if we as human species are going to the stars then maybe we want to go faster :)  8)
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