Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 420028 times)

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1080 on: 12/16/2015 11:29 PM »

That "nonsense" that every transport system mfg and operator follows which does not operate a transport system based around a design for a strategic weapon system uses?

Of course if they did space launch using say, some refurbished artillery pieces they probably would follow the combined mfg/operator model as well.

Funny how that's not taken off as a concept, isn't it

The nonsense is the comparison to ICBMs and strategic weapon systems,

Space Launch is different than other transport systems because of the energies involved and it is a transitional system.  All other modes of transport have a steady state mode of operation, where most parameters are static.  Also, when power is removed, all other modes have graceful degradation.

Offline pippin

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The Reaction Engines Skylon Master Thread (5)
« Reply #1081 on: 12/16/2015 11:29 PM »
Btw, I don't get the point why everybody here seems to assume that building and operating a space launch vehicle in the same entity would be something totally common just because that's how SpaceX and some other NewSpace companies are trying to do it. I mean... That's quite a new model, not even ULA has operated that way until now.

And strategic weapon systems are definitely not being operated by their manufacturers
« Last Edit: 12/16/2015 11:32 PM by pippin »

Offline Star One

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1082 on: 12/17/2015 06:47 AM »
Hypersonic strategic air-lift anyone?

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Potentially beneficial developments include faster computer processing, lighter logistics chains, 3D printing and “perhaps even hypersonic strategic air-lift”, plus autonomous weapon systems such as unmanned combat air vehicles.

https://www.flightglobal.com/news/articles/uk-predicts-more-stealthy-and-stand-off-ops-by-2035-420125/

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1083 on: 12/17/2015 09:02 AM »
The nonsense is the comparison to ICBMs and strategic weapon systems,
Not really. All current LV's are multi stage one shot designs, exactly like ICBM's. the biggest difference is they trade the performance of liquid fuels with poor long term storage (in flight weight tanks) over the long term storability of solids. I think ICBM's also tend to operate to higher g limits but I have no doubts you could back convert any current generation ELV to an ICBM quite easily. I'm not saying anyone would want to, simply that with a suitable (nuclear) payload it would not be that difficult and everyone interested in this subject knows that.
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Space Launch is different than other transport systems because of the energies involved and it is a transitional system.  All other modes of transport have a steady state mode of operation, where most parameters are static.
Now that is true, although it could be said that the stable orbit part is the "cruise" state.
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Also, when power is removed, all other modes have graceful degradation.
You're extending assumptions and design decisions from one launch mode to another.

Let's unpack you're assumptions.
When an LV takes off vertically (IE Thrust must exceed GTOW) with no engine out capability and an engine fails it has no graceful degradation.

Which is true.

The corollary of which is a)Design in engine out capability and/or  b)Don't take off vertically.

There is also the subtle point that all 1st stage engines should be "equal," otherwise you get the Shuttle architecture where any engine failed at takeoff and you're doomed, although you're more doomed if one of the SRB failed, as they provided 90% of the T/O thrust.

These are design decisions, not laws of physics.

The fact something has always been done a certain way does not mean a)It's the best possible way and b)That other ways will compete or replace it.

This seems a very simple idea yet it seems almost impossible to explain to some people.  :(
Btw, I don't get the point why everybody here seems to assume that building and operating a space launch vehicle in the same entity would be something totally common just because that's how SpaceX and some other NewSpace companies are trying to do it. I mean... That's quite a new model, not even ULA has operated that way until now.
They're not.  Historically on paper there is actually an ELV building company and a launch services company. But (also historically) this has made no real difference as they are both parts of the same company.

I'd check the small print to see if those companies have a contract with "Space Exploration Inc" or something like "Space Exploration Launch Services Inc"

Only Sea Launch or Arianespace come near  the idea of a true separation between the mfg side and launch ops side.

Now the question is wheather it's difficult to have such a separation because it's orbital launch or because it's orbital launch conducted with basically an expendable weapons architecture.

Some think any orbital launch system is doomed to a mfg/operator,  others that it's the VTO ELV or attempted VTO semi RLV architecture that's the problem.  My view is that separation of tasks was not a design driver for ICBM's. REL's market analysis indicate there are a lot of people who want to launch payloads but don't want to fund an ELV to do so because they see no benefit in having yet another ELV, with it's usual 5% failure rate, destroyed after 1 use characteristics.

IOW they want an asset that gets the job done, not a development programme.
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And strategic weapon systems are definitely not being operated by their manufacturers
But then they are delivered in orders of 100's,not ones and twos, and a few percent failure was anticipated, as they were designed to fight WWIII. At heart their ConOP was "Press button A to open silo, turn key at same time as partner (so one guy going nuts can't launch it) and press button B to launch"

Incidentally ICBM's also benefited from hghly  standardized payloads, which keep non recurring (but quite large) engineering costs down.

Hypersonic strategic air-lift anyone?
https://www.flightglobal.com/news/articles/uk-predicts-more-stealthy-and-stand-off-ops-by-2035-420125/
And possibly matter transmission and time travel as well.   :)

One of the skills in reading a govt report written by a civil servant keen to demonstrate a)How they've read everything on their subject or b) who is trying to advance a personal agenda is to spot "everything-but-the-kitchen-sink" sentences.

And let's keep in mind that right now most of the enemies the UK is in dispute with don't actually have an airforce, and their air defense weapons were mostly handed to them by the people the coalition of countries that the UK is a part of handed them to for their defense.  :(

Which suggests if the UK doesn't want to deal with advanced air defenses it shouldn't hand them to people who will turn them over to it's enemies at the first sign of trouble.  :(
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline pippin

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1084 on: 12/17/2015 10:17 AM »
They're not.  Historically on paper there is actually an ELV building company and a launch services company. But (also historically) this has made no real difference as they are both parts of the same company.
"Historically", LVs have been built by companies and operated by NASA and the Air Force (SU had a somewhat different model).
For the last 25 years there have been private companies taking over the operator side and they have pretty much tried a broad range of different setups (Arianespace, ULA, LM, Boeing, ILS, Seal Launch, Orbital, SpaceX, each of them has or had a different business model).

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Now the question is wheather it's difficult to have such a separation because it's orbital launch or because it's orbital launch conducted with basically an expendable weapons architecture.
It's not difficult because you have very little standardization and few launches. For Airline traffic you have tens of thousands of planes being operated by hundreds of airlines and specialized service organizations. Also with all kinds of different levels of vertical integration.

With Space Launch you have 10-20 launches per system per year and to build up 5 different organizations having the launch and service knowledge doesn't make an awful lot of sense.

If you have one Skylon it will be the same. 3 or 4, too.
If you have 100 Skylons it will surely happen.

In any case you can of course separate the build and launch organizations because you might or might not want to have a different structure depending on your preferences about vertical integration (Musk vs. McKinsey being the two extreme side of philosophies....)

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But then they are delivered in orders of 100's,not ones and twos
Bingo. so it was easier to have a clear separation between manufacturer and operator. Just harder to compute with very few vehicles/launches so whatever your model you usually find yourself in a setup with only a few players.

As usual, it boils down to flight rates...
« Last Edit: 12/17/2015 10:17 AM by pippin »

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1085 on: 12/17/2015 12:07 PM »

As usual, it boils down to flight rates...

True, but over a period of 30 years. So assuming that the price of a Skylon vehicle is about 1bn Eur. if it flies only once in 30 years, then it is a 1b+operative costs flight. to compete with a partial reusable F9, assuming SpaceX is able to reduce costs down to 50% of F9, you need to compete in the range of 30M/launch.

If REL's own estimates on operative costs are correct, operative costs are about 5M/flight.  Which means that, over a period of 30 years, a single Skylon vehicle must fly about 40 times to compete with a partially reusable F9.
Which means a flight rate of about 1.3 per year.
NOT an impossible achievement I'd say....

Now, with 1 Bn pricetag, REL would need to sell about 20 Skylons in total to cover up expenses and realise a meaningful profit. in total, not simultaneously. Assuming they can sell it at a rate of 1 each 2 years, this means that, at the top of the curve, there will be a max of 15 skylons operating simultaneously.

Therefore, if F9-partialR remains the best competitor (assuming no inter-skylon competition, which is a bad assumption I aknwoledge), the total  Skylon fleet flight rate, at most, will require no more than 20 flights per year divided over a full fleet of 15 vehicles.

Again, not an impresive number.
« Last Edit: 12/17/2015 12:14 PM by francesco nicoli »

Offline pippin

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1086 on: 12/17/2015 12:25 PM »
True, but over a period of 30 years.
A flight rate is a flight rate, no matter how long you maintain it.
You don't pay for maintaining a launch organization and infrastructure per launch (OK, you do if your flight rate is _really_ high but then we need no discussion here) but per year.

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So assuming that the price of a Skylon vehicle is about 1bn Eur. if it flies only once in 30 years, then it is a 1b+operative costs flight.
Yep. But if it flies TWICE in 30 years, one today and once in 30 years, then the cost of keeping that infrastructure and team you don't need for 29 years _really_ kill you. Sorry, these extreme cases just get you nowhere in the discussion.

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assuming SpaceX is able to reduce costs down to 50% of F9
Here, too, a static assumption makes little sense since this, too, will depend on the flight rate...

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If REL's own estimates on operative costs are correct, operative costs are about 5M/flight.
If REL's own estimates are static they are wrong. Period. If they are not, we need to discuss flight rates.

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Which means that, over a period of 30 years, a single Skylon vehicle must fly about 40 times to compete with a partially reusable F9.
Even if that partially reusable F9 makes it's 10 flights in one year? No way. Keeping the team and infrastructure around for 30 years will be dramatically more expensive than having it for one year, your initial Skylon investment will pale in comparison. Especially now that interest is a thing again...

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NOT an impossible achievement I'd say....
Completely impossible. The maintenance and operations will kill you, cost wise. Hangar, runway, payload handling facilities, fuel handling facilities, team, all of that for 1.3 flights a year? No way that's ever going to be economical.


Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1087 on: 12/17/2015 12:31 PM »
Now that is true, although it could be said that the stable orbit part is the "cruise" state.

No, that is completely separate and different.  Environments are different, control is different, etc.

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1088 on: 12/17/2015 12:39 PM »
The same people that design the rocket are the same as ones doing integration and flight analysis.  The same people that buy off impacts from manufacturing discrepancies are the ones that buy off new launch environments. 

Offline Space OurSoul

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1089 on: 12/17/2015 04:19 PM »
I wonder if insurance costs would emerge from the noise at those projected launch costs.
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.
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Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1090 on: 12/17/2015 05:20 PM »
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

Offline sghill

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1091 on: 12/17/2015 07:20 PM »
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

And wings so small it's glide path would charitably be 4 to 1 if we use the X-15 as an example and 1 to 1 if we use the shuttle.
« Last Edit: 12/17/2015 07:25 PM by sghill »
Bring the thunder Elon!

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1092 on: 12/17/2015 07:38 PM »
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

And wings so small it's glide path would charitably be 4 to 1 if we use the X-15 as an example and 1 to 1 if we use the shuttle.

If it's designed to abort then presumably it can do so.  That has to have insurance value, doesn't really matter what one might think of it as a flying machine.

Offline Space OurSoul

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1093 on: 12/17/2015 08:18 PM »
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

I think it's fair to claim that shuttle and Skylon's returned payload would be equivalently damaged if there were a RUD in either case. Now, I'm not exactly a Skylon fanboi, but I think, if Skylon fulfills its design, some stronger claims could legitimately be made about less-catastrophic failure modes.
Skylon is intended (which I recognize is a heck of a long way from demonstrating) to provide intact abort-to-runway-landing throughout the early phase of launch, absent a RUD. Shuttle couldn't even have claimed let alone provided that. There's water on board whose sole purpose is brake cooling for abort before liftoff, and the required runway length is only that long so that it can enable these aborts. The tail is sized for coping with single-engine-cluster operation at low speed, so RTLS is designed to be possible at any point even with one whole nacelle out of action. It is designed to cruise (at Mach 3) on bypass ram engines alone, enabling intact abort to a wide range of destinations late in the launch phase even with both sets of rockets out of action.
But the most important point is that they plan 400 launches to orbit (200 for each prototype) before selling the first Skylon, and each individual instance is intended to receive 2 or 4 (forget the exact number) full flights before being delivered.
That history, both of the type and of the individual craft, plus all those intact abort modes to a benign runway landing, would allow a demonstrably reduced chance of loss of payload. Hence cheaper insurance when compared to vertical-takeoff, even when compared to a vertical-takeoff system with an equivalent flight history.
I think it is fair to argue, however, that the odds of one of these intact-abort scenarios are low enough that perhaps the advantage isn't that great.

(N00b argues with Jim. DUCK!)

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Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1094 on: 12/17/2015 08:24 PM »

plus all those intact abort modes to a benign runway landing,


What says an intact abort is a benign runway landing?

Offline Space OurSoul

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1095 on: 12/17/2015 09:41 PM »

plus all those intact abort modes to a benign runway landing,


What says an intact abort is a benign runway landing?

That's their design goal, at least.
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Offline t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1096 on: 12/18/2015 12:54 AM »
There's an intriguing sentence here:

https://www.gov.uk/government/publications/future-operating-environment-2035

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There are exciting prospects ahead for operational commanders who relish such challenges.  While these may appear
daunting, other developments may ease the task in hand.  Computer processing power has already been mentioned.  The commander may also be able to exploit lighter logistic chains, courtesy of additive printing, or perhaps even hypersonic
strategic air-lift.

:-)

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1097 on: 12/18/2015 09:24 AM »
Advantage Skylon, I think, since it would be demonstrably more likely that you'd get your payload back if the launch failed.

Same spin was used for the shuttle.  It would be worse.  What you get back is potentially damaged spacecraft filled with hazardous propellant.

And wings so small it's glide path would charitably be 4 to 1 if we use the X-15 as an example and 1 to 1 if we use the shuttle.
If you're talking about Skylon you should keep in mind that while those wings look small it is much better balanced than Shuttle, its fuselage is much more aerodynamic (no slab sides) and most of that shape (which will probably generate significant lift on its own) is empty.

It should be noted that most of the events and failure modes of a Shuttle launch simply don't happen in Skylon. I'm sure there will be a significant number of critical failure modes (as any complex vehicle has) An obvious concern being bird strikes to the inlets (discussed at great  length in earlier threads)

So what are people speculating on ? Logically FOD is an issue but methods exist to deal with that concern.

AFAIK there are no stats for damage to satellites on the Shuttle. It never happened.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1098 on: 12/18/2015 09:25 AM »
There's an intriguing sentence here:

https://www.gov.uk/government/publications/future-operating-environment-2035

Quote
There are exciting prospects ahead for operational commanders who relish such challenges.  While these may appear
daunting, other developments may ease the task in hand.  Computer processing power has already been mentioned.  The commander may also be able to exploit lighter logistic chains, courtesy of additive printing, or perhaps even hypersonic
strategic air-lift.

:-)
Seen before. Already commented upon.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline flymetothemoon

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1099 on: 12/18/2015 10:25 AM »
It is designed to cruise (at Mach 3) on bypass ram engines alone, enabling intact abort to a wide range of destinations late in the launch phase even with both sets of rockets out of action.

Well I have been interested in Skylon for a long time and never come across that gem of info before. That's quite something. With all main engines out it can still propel itself with the bypass ramjets? Is this a fact?

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