Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 419867 times)

Offline Archibald

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #980 on: 12/04/2015 04:24 PM »
It's interesting to think that being able to have a name is one aspect of re-usability.   Why name something that is destroyed the first time you use it?

How powerful names like "Enterprise"  or "Ark Royal" or "Illustrious" are!  It will be sad if Skylons only get numbers.   I hope they get named and that the names live again and again like ship names do.


Just name them from all those battleships Britain build between 1890 and 1940. They build a crapton of them.

Online adrianwyard

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #981 on: 12/04/2015 04:29 PM »
Unless someone has a time machine, any thread thatís discussing events a decade out or more is going to have to humor both optimists and pessimists arguing their cases. But without details or insights this back and forth is dull, dull, dull.

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #982 on: 12/04/2015 04:33 PM »

Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..

No, I will continue to point out the nonsense

Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #983 on: 12/04/2015 04:36 PM »

Given that Skylon doesn't have to be assembled at the site or transported there by machines, is that certain?  At the very least doesn't one need a lot less people and/or equipment?

Presumably it also needs quite a lot less liquid oxygen storage than a conventional launcher might.

On the other hand, if there is a high flight rate (in surges perhaps) then one might need much more propellant storage than a conventional launch site..

Still needs a lot of LH2, so the amount of LOX doesn't matter.  Still need a hangar much like the shuttle.  Still need payload processing area.  So look at Spacex pad but without the erector.

Online adrianwyard

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #984 on: 12/04/2015 05:08 PM »
One of the phrases used in connection with Skylon that raises eyebrows is Ďaircraft-like operationsí.

Optimists picture a Skylon landing - much like a passenger jet - someone kicking the tires, filling up the tanks, loading a new payload, and then sending it back into orbit. And of course cashing the check.

For this to happen REL will have to accomplish a second breakthrough in space technology in addition to air breathing propulsion: a never-before-seen ultra low maintenance spacecraft (and all associated systems: RCS, OMS, TPS, landing gear/braking, aerosurfaces/actuators, etc.)

REL clearly expect to achieve this, hence the 200 flight test plan. But itís not been done before. You can flip the reusability argument on its head and call expendable vehicles Ďmaintenance freeí. Sitting here in 2015 we donít know what infrastructure will be needed to keep Skylon flying. But we do know itís more than throwaway rockets need :-)

The maintenance of a passenger jet is low because much of the time itís earning money itís at cruise. And thatís a very benign environment - not that much different to being in the hangar. But this will not be the case for Skylon: ironically it will not be aircraft-like.

During the test flights REL will learn which systems need to be maintained with what frequency. If they get it all right first try, then the aircraft infrastructure analogy holds. Minimal inspection and maintenance will be done at the launch site (so it will require less pad infrastructure than STS.) And Skylon is only moved back to the assembly facility for major overhauls.

But realistically, we canít expect them to get it all right first try - some system will have teething trouble and need to be inspected/tweaked/swapped out. And now the launch facility begins to look more and more like the factory.

Can we predict if Skylon will be gas-and-go for 200 flights, or need to be rebuilt every flight? Nope, not yet.

Offline 93143

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #985 on: 12/04/2015 05:10 PM »
they plan a 200 flights test programme.

~400, not 200.  Two vehicles, two years.  One vehicle doing envelope exploration and about 30 abort tests, the other doing 204 orbital launches to demonstrate the specified service lifetime (200 flights, plus the 4 test flights each unit undergoes before delivery).

I believe this was subsequent to the maybe-not-orbital boilerplate vehicle tests.

There may be newer information, but I don't recall seeing it.
« Last Edit: 12/04/2015 05:17 PM by 93143 »

Online adrianwyard

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #986 on: 12/04/2015 05:17 PM »
Right, ~400. But frankly this plan only tells me their heart is in the right place. Not that they can achieve it.

They could just as easily say ~1000 to cover even more of the edge/abort cases. Or ~100 which would give them parity statistics with other vehicles.

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #987 on: 12/04/2015 06:48 PM »

Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..

No, I will continue to point out the nonsense

if you think it adds to the discussion, feel free. But I think is more poisonous than else.

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #988 on: 12/04/2015 06:50 PM »
they plan a 200 flights test programme.

~400, not 200.  Two vehicles, two years.  One vehicle doing envelope exploration and about 30 abort tests, the other doing 204 orbital launches to demonstrate the specified service lifetime (200 flights, plus the 4 test flights each unit undergoes before delivery).

I believe this was subsequent to the maybe-not-orbital boilerplate vehicle tests.

There may be newer information, but I don't recall seeing it.

well, even better then. Waiting for investors...

Offline lkm

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #989 on: 12/04/2015 09:24 PM »
Did I say they had built one?
 I said they had designed an engine cycle and built a heat exchanger which they indisputably have done and which multiple institutions such as ESA, AFRL, DSTL, UKSA, BAE and DLR seem to recognize as an achievement worth noting and/or funding, you may not consider it an achievement warranting praise but clearly these things have been achieved by the company and praise is not a necessary condition of achievement.

There are many designs that have never left the factory or even drawing stage.  There aren't "off the drawing board" ceremonies, there are rollout ceremonies.

Absolutely true and if you've been reading the thread you'll have seen that I gave odds that it was more likely than not that Skylon won't be built but it's clearly not true that theoretical work in science and engineering is never celebrated.

One of the phrases used in connection with Skylon that raises eyebrows is Ďaircraft-like operationsí.

Optimists picture a Skylon landing - much like a passenger jet - someone kicking the tires, filling up the tanks, loading a new payload, and then sending it back into orbit. And of course cashing the check.

For this to happen REL will have to accomplish a second breakthrough in space technology in addition to air breathing propulsion: a never-before-seen ultra low maintenance spacecraft (and all associated systems: RCS, OMS, TPS, landing gear/braking, aerosurfaces/actuators, etc.)

REL clearly expect to achieve this, hence the 200 flight test plan. But itís not been done before. You can flip the reusability argument on its head and call expendable vehicles Ďmaintenance freeí. Sitting here in 2015 we donít know what infrastructure will be needed to keep Skylon flying. But we do know itís more than throwaway rockets need :-)

The maintenance of a passenger jet is low because much of the time itís earning money itís at cruise. And thatís a very benign environment - not that much different to being in the hangar. But this will not be the case for Skylon: ironically it will not be aircraft-like.

During the test flights REL will learn which systems need to be maintained with what frequency. If they get it all right first try, then the aircraft infrastructure analogy holds. Minimal inspection and maintenance will be done at the launch site (so it will require less pad infrastructure than STS.) And Skylon is only moved back to the assembly facility for major overhauls.

But realistically, we canít expect them to get it all right first try - some system will have teething trouble and need to be inspected/tweaked/swapped out. And now the launch facility begins to look more and more like the factory.

Can we predict if Skylon will be gas-and-go for 200 flights, or need to be rebuilt every flight? Nope, not yet.

Keep in mind that there is a paper stating the intention that the first tranche of Skylon production after the test programme is sold expensively to only experienced institutional operators (as Jim says at first very few organisations will have the know how to operate Skylon)  to allow for the proper commercial  maintenance and flight operations procedures to be developed and the initial operations feedback to feed into the second tranche of production which can be sold at a more affordable price to to a broader range of commercial operators along side a package of operational knowledge and maintenance. I would assume the 2 day turn around is something to be available once the broad commercial availability stage has been reached.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #990 on: 12/05/2015 12:24 AM »
Or no one will buy a Skylon because they'll be taking a huge risk.

Reaction Engines and their partners will necessarily HAVE to operate Skylon for quite a while before they'll sell any.

Of course: they plan a 200 flights test programme. MORE than practically any other orbital launch vehicle to date, afaik.
He means REL selling launches after the 400 flight test programme (on 2 vehicles).

Note that The Aerospace Corporations  "3/8" rule that a failure within 3 launches (of an ELV)  is usually a design failure, within 8 it's probably a materials failure
They very likely will be on the same scale.  Hangars, propellant storage, payload processing facilities would be the same.
Actually given the size of the vehicle and the tanks I never expected them to be smaller.

However you missed out "Launch Control, Range Safety and Mission control"

I expect launch control to be much smaller given the higher structural margins and the underlying assumption that Skylon will work, rather than something that's a hairs breadth away from falling apart.

I would expect Range Safety to be autonomous on the vehicle. with engine shut down and propellant dumping ( no self destruct charges) to be SOP.

Mission Control? Isn't that what happens in an airport Control Tower? Shared across all vehicles using the runway.

So look at Spacex pad but without the erector.
The word you're looking for is "runway."  :)
"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 Robotbeat

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #991 on: 12/05/2015 01:28 AM »
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.

There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.

And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #992 on: 12/05/2015 07:31 AM »
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme.

Does that really sound like a fair comparison to you?

For an uncrewed, non passenger carrying vehicle (to begin with) with 2 development vehicles and being able to draw on roughly 100 years of flight test protocols I think the situation is much more favorable. Skylon is big and it's speed range is wide but it's aerodynamics are relatively (no "shuttle cock" re configurations) simple. It's statically stable (something Shuttle was not) and a great deal more is known about shocks on (and in) inlets since the the days Lockheed flew 66 flights to calibrate the SR71 inlets. I'm not sure how many flights Concorde or the Tu144 took to set their inlets up.
Quote
And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.
What specifically are you talking about?

Modern aircraft SOP is to fly with extensive servicing data being recorded (and in the case of some engines being transmitted to a central station while in flight) to monitor off line. That's been happening for 40+ years.

Large aircraft operations since 1954 (first flight of the C130 Hercules) or 1968 (first flight of C5A Galaxy), along with the Shuttle history have taught many lessons on operations & servicing, many of which can (and will) be incorporated before  Skylon is built That's a minimum 47 years of flight and maintenance experience (of large aircraft) to draw on.

In contrast the servicing procedures for any two stage vehicle with any degree of reuse are still being worked out, since the last 2 stage commercial (reusable) aircraft system flew in the 1930's. That puts SS2 about 75 years behind the fixed wing aircraft field in practice. Since no one's done VTO reuse (except in helicopters) SX will start from scratch.
Quote
There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.
And yet Airbus did not do this (and AFAIK no other large passenger mfg in China or Russia has done this either).
BTW You're mistaking revenue for return on their investment. The classic way to realize ROI in modern times has been through an IPO. Outright Skylon sales would increase initial offer share price as there is solid potential for share dividends, unlike say Facebook, who's launch P/E ratio was in fractions of a century.

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And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.
Yes we can really see your doubts. :(

There are 3 ways you can solve a  problem.

Create a design, then find materials to implement it.

Evolve a design based on a fairly good knowledge of a materials strengths and weaknesses.

Build a vehicle like previous ones and try and "fix" it after you've built it to meet new more demanding criteria.

I'll leave you decide which RLV's fit in which category and what level of risk each approach has in reaching your end goal.
« Last Edit: 12/05/2015 07:48 AM by john smith 19 »
"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 Archibald

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #993 on: 12/05/2015 01:05 PM »
The fact is that Skylon  cryogens propellants, unpiloted mode,3 miles long take-off run and very high takeoff speed - all forbbide access to any airport. The FAA will never certify Skylon for LAX, JFK or Roissy CDG or Heathyrow. Just sayin'

Which doesn't mean Skylon is unseful. We still need a SSTO to lower the cost of a pound per orbit.

Offline Robotbeat

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #994 on: 12/05/2015 01:09 PM »
I mean selling launches /before/ all orbital launches have been completed.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme....
And I see you ignored the "and other reusable test-bed vehicles."
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #995 on: 12/05/2015 05:46 PM »
And I see you ignored the "and other reusable test-bed vehicles."
I presume you're talking about Grasshopper and SX's efforts here, or did you have some other test bed in mind?

So we've gone from the nearest winged to an attempted VTOL testbed.

A configuration that was guaranteed to have control issues from the start. It's no accident that all the plug nozzle based designs of Philip Bono in the 60's and the planned DC-1 were all kind of squat, since high aspect ratio designs, IE all ELVs were expected to be "floppy" and difficult to control.

Turned out they were right, even with 21st century computer speeds and program sizes.

That comes under the heading of "Starting with a design and trying to fix it." May be possible, may not be, but you can't put research on a clock.

SX are getting better at it but it's taken them a long time to do so.

SX are true pioneers and their heroic efforts to make this landing mode work are (I suspect) under appreciated. Slosh loads, deck winds, a landing pad that can fall or rise several meters. These are just a few issues the team has to contend with.

The fact is that Skylon  cryogens propellants, unpiloted mode,3 miles long take-off run and very high takeoff speed - all forbbide access to any airport. The FAA will never certify Skylon for LAX, JFK or Roissy CDG or Heathyrow. Just sayin'
People have been talking about Methane and LH2 for passenger aircraft since the 1970's, and a ferry mode Skylon will be 160 tonnes lighter with a much shorter takeoff run. Landing it will have neither on board cryogens nor high landing speed. In fact the key issues for an existing airport are likely to be it's a UAV and it's going to loud on takeoff.

BTW the FAA's writ does not run to France or the UK. And if it's not built in the US Skylon will not need their permission to operate in those airports to do so. Just saying'
"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 93143

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #996 on: 12/05/2015 10:14 PM »
Just so we're clear, it was never the intent to operate Skylon from an existing airport.  Emergencies are potentially a different matter, and if you really don't want liquid hydrogen on site, or you don't want the engines lit for the takeoff, you could always tow it.  But the usual mode of operation would be from a dedicated spaceport.

Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

If I'm not mistaken, this would be after the boilerplate prototype testing to ensure the system works.  It would be in large part a certification test series similar to what an airliner would go through.

(Also, it wasn't strictly two years - just less than three.)
« Last Edit: 12/06/2015 12:12 AM by 93143 »

Offline Robotbeat

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #997 on: 12/06/2015 12:28 AM »
Just so we're clear, it was never the intent to operate Skylon from an existing airport.  Emergencies are potentially a different matter, and if you really don't want liquid hydrogen on site, or you don't want the engines lit for the takeoff, you could always tow it.  But the usual mode of operation would be from a dedicated spaceport.
So customers would not only have to pay for their own Skylon or two, the ground support equipment required for it, payload processing building, but also a dedicated airport? Sounds like any possible payoff is further and further away for their potential customers. Since RE will need all this stuff (perhaps minus the payload processing) anyway just to prove out Skylon, they'll have a super easy opportunity to just start launching payloads themselves... (Which is fine with me, by the way.) It seems quite likely they'd be stuck in a situation where they paid for almost all the equipment needed to launch payloads themselves, but without being able to convince anyone to build a dedicated airport and buy all the ground support equipment and the Skylons needed to start service.

...Of course, I doubt they'd be stuck in that situation, since I'm sure they'd realize it before anything like a prototype flies.

Quote
Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.

If I'm not mistaken, this would be after the boilerplate prototype testing to ensure the system works.  It would be in large part a certification test series similar to what an airliner would go through.

(Also, it wasn't strictly two years - just less than three.)
I thought the 400 flights info comes from before they planned the boilerplate prototype?
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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #998 on: 12/06/2015 12:40 AM »
While there are many unknowns with Skylon, one pretty safe bet is as follows: If it ever launches payloads to orbit, it will launch them from Kourou and return there. If in doubt, it's better to think of Skylon as currently spec'd by REL is a spacecraft, not an aircraft.

Offline Impaler

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #999 on: 12/06/2015 05:25 AM »
If 400 test flights are planned then it would be a crying shame to haul 6,000 mt of dummy payloads to orbit.  After say a dozen successes you might as well start using all that capacity and stimulating the market with a low cost to orbit so that your potential vehicle customers actually SEE the huge demand bubbling up that would be necessary to justify purchasing a vehicle.

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