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#1 2012-04-28 13:16:06

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Reaction Engines

Have these guys been discussed before?

http://www.bbc.co.uk/news/science-environment-17874276

They seem pretty confident about their abilities, and I guess if they have the engine, the rest might follow.

It would be a first for the UK to have any really strong contribution to the space effort, so that would be nice.


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#2 2012-04-28 16:15:41

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Louis:

They're a long way from flying yet,  but I really do hope it works.  I know how to do the same job with a parallel-burn combination of rockets and ramjets in a two-stage airplane,  but this would be loads better.  Single stage at realistic mass fractions (and that is one big hell of an if!!!!!) would always be better. 

Skylon's biggest problem has always been lack of funding.  Fix that,  and one only must contend with technical results.  Technical results is always a faster path than funding,  for everything I can remember.  And,  I'm an old guy.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#3 2012-04-28 17:09:04

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

GW Johnson wrote:

Louis:

They're a long way from flying yet,  but I really do hope it works.  I know how to do the same job with a parallel-burn combination of rockets and ramjets in a two-stage airplane,  but this would be loads better.  Single stage at realistic mass fractions (and that is one big hell of an if!!!!!) would always be better. 

Skylon's biggest problem has always been lack of funding.  Fix that,  and one only must contend with technical results.  Technical results is always a faster path than funding,  for everything I can remember.  And,  I'm an old guy.

GW

Well it would be nice if the UK could finally make a contribution to us getting off the planet. The UK had quite a nice space effort going in the 50s and early 60s but what with our military commitments and slow growth it was abandoned.

Do you think it's down to a question of using advanced lighter materials as components? They must be carrying a lot of mass with that cooling equipment forming part of the craft.


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#4 2012-04-28 17:17:52

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Louis:

No,  the real problem is one of making heat transfer occur as fast as the other propulsion processes,  when it truly and fundamentally does not want to be that fast.  Skylon's engine is basically a liquid air cycle engine.  No one else has ever made liquid air that fast,  ever.  But,  Reaction Engines just might.  I'm rootin' for 'em. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#5 2012-04-28 17:46:17

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

GW Johnson wrote:

Louis:

No,  the real problem is one of making heat transfer occur as fast as the other propulsion processes,  when it truly and fundamentally does not want to be that fast.  Skylon's engine is basically a liquid air cycle engine.  No one else has ever made liquid air that fast,  ever.  But,  Reaction Engines just might.  I'm rootin' for 'em. 

GW

Me too!


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#6 2012-04-29 18:40:33

Rune
Member
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Reaction Engines

I've also been following Skylon for a number of years. They are certainly shooting high in their ambitions! Full-fledged SSTO, HTOL, no less. The whole shebang. It is a harsh road they are traveling, especially funding-wise, but it could very well end up working and getting european space efforts into the history books. The first real SSTO would indeed be a very big deal, and the precooler seems pretty much done (a full-sized prototype is undergoing testing right now, as is shown on the video). It's a definite maybe, and I hope they succeed, get their funding, start selling spaceplanes, and enter my personal hall of fame.


Rune. As a side project, they are also developing the world's first hypersonic antipodal airplane, the LAPCAT A2. O_O


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#7 2012-04-30 06:38:35

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

Rune wrote:

I've also been following Skylon for a number of years. They are certainly shooting high in their ambitions! Full-fledged SSTO, HTOL, no less. The whole shebang. It is a harsh road they are traveling, especially funding-wise, but it could very well end up working and getting european space efforts into the history books. The first real SSTO would indeed be a very big deal, and the precooler seems pretty much done (a full-sized prototype is undergoing testing right now, as is shown on the video). It's a definite maybe, and I hope they succeed, get their funding, start selling spaceplanes, and enter my personal hall of fame.


Rune. As a side project, they are also developing the world's first hypersonic antipodal airplane, the LAPCAT A2. O_O

Space X should buy them up now, open a European operation.


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#8 2012-04-30 07:02:30

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,160
Website

Re: Reaction Engines

No, SpaceX is trying to run with established technology and make it cheaper; Skylon are going for cutting edge R&D. A merger would do neither good...


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#9 2012-04-30 11:21:24

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

Terraformer wrote:

No, SpaceX is trying to run with established technology and make it cheaper; Skylon are going for cutting edge R&D. A merger would do neither good...

Depends how you look at it. I think there would be synergy for both. I think it would complement SpaceX's range, meaning that in due course it could come to dominate space and lunar tourism. Essentially Skylon would be offering a passenger service - and passengers aren't that heavy a payload.


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#10 2012-04-30 15:18:13

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,160
Website

Re: Reaction Engines

SpaceX has Dragon... I think Skylon should acquire SpaceX, so that SpaceX is a British company... tongue


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#11 2012-04-30 16:03:02

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

Terraformer wrote:

SpaceX has Dragon... I think Skylon should acquire SpaceX, so that SpaceX is a British company... tongue

There's no comparison between sitting upside down on top of a rocket (aka a bomb) and the future offered by Skylon: a much more plane like experience to get you into space.

Something like Skylon is needed for longer term development of space tourism I think.


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#12 2012-05-01 06:21:19

Rune
Member
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Reaction Engines

Well, I'd rather see both companies compete to bring the cost down and not get stuck with a single provider of reusable launch services. You know, bring the cost down as much as it is possible. Plus, different business models. Reaction engines wants to sell the vehicles, SpaceX wants to sell launch services. Other than that, both should be similarly comfortable for a passenger. Oh, and skylon is almost every bit a bomb as a rocket is, only it has less oxidizer at the point where the atmosphere can burn the H2 with no problems, and no escape system (it is a rocket most of the way to orbit, after all).


Rune. Let the best rocket win.


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#13 2012-05-01 09:22:46

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Well,  passenger safety with a launch rocket such as Falcon-9 or Falcon-Heavy depends upon a good escape system.  I think Spacex's use of the capsule itself fully powered as the escape vehicle,  is a better idea than the old escape tower we used on Mercury and Apollo.  You have coverage from ignition all the way to orbit.  The tower didn't work after jettison. 

With an airliner-like vehicle (such as Skylon),  you have to make the craft "utterly reliable" so that no escape system is needed (sounds hauntingly familiar,  like "make the ship unsinkable",  right?  Well,  that's exactly what you have to do). 

That's what we tried to do with shuttle,  and failed.  A fragile heatshield,  exposed to debris impact in a side-mounted cluster,  is two strikes against you right there.  Add foam insulation that peels off,  and you kill a crew.  We did. 

That's why Skylon is proposed as an unmanned cargo vehicle.  Flying it like that for a while will uncover all the "gotchas",  which can be fixed in a follow-on design that could be manned.  That's actually the smart way to do it.  Because of its unique engines,  Skylon is really a feasibility demonstration vehicle.  Until we've flown it for a while. 

Any high-energy vehicle,  be it a vertical launch rocket or some kind of spaceplane,  will be risky.  That is just plain unavoidable.  But it can be managed and designed-for.

Feasibility of spaceflight itself is no longer in doubt.  For passenger service,  we need to get the safety-of-flight engineers in on the ground floor of all vehicle designs from now on.  After 50+ years,  we're finally doing that.  They did it at Spacex,  and I'm proud of them for it. 

Actually,  there was a way to have saved both shuttle crews,  and it was not what they implemented.  My idea was hindsight-only for Challenger,  but afterward it was never done,  which is why Columbia's crew died.  I couldn't get NASA to listen to me.  Outsider,  "not invented here",  and all that jazz.  But to this day I still show spaceflight crew escape concepts on my resume as something I consult in. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#14 2012-05-01 16:28:48

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

GW Johnson wrote:

Well,  passenger safety with a launch rocket such as Falcon-9 or Falcon-Heavy depends upon a good escape system.  I think Spacex's use of the capsule itself fully powered as the escape vehicle,  is a better idea than the old escape tower we used on Mercury and Apollo.  You have coverage from ignition all the way to orbit.  The tower didn't work after jettison. 

With an airliner-like vehicle (such as Skylon),  you have to make the craft "utterly reliable" so that no escape system is needed (sounds hauntingly familiar,  like "make the ship unsinkable",  right?  Well,  that's exactly what you have to do). 

That's what we tried to do with shuttle,  and failed.  A fragile heatshield,  exposed to debris impact in a side-mounted cluster,  is two strikes against you right there.  Add foam insulation that peels off,  and you kill a crew.  We did. 

That's why Skylon is proposed as an unmanned cargo vehicle.  Flying it like that for a while will uncover all the "gotchas",  which can be fixed in a follow-on design that could be manned.  That's actually the smart way to do it.  Because of its unique engines,  Skylon is really a feasibility demonstration vehicle.  Until we've flown it for a while. 

Any high-energy vehicle,  be it a vertical launch rocket or some kind of spaceplane,  will be risky.  That is just plain unavoidable.  But it can be managed and designed-for.

Feasibility of spaceflight itself is no longer in doubt.  For passenger service,  we need to get the safety-of-flight engineers in on the ground floor of all vehicle designs from now on.  After 50+ years,  we're finally doing that.  They did it at Spacex,  and I'm proud of them for it. 

Actually,  there was a way to have saved both shuttle crews,  and it was not what they implemented.  My idea was hindsight-only for Challenger,  but afterward it was never done,  which is why Columbia's crew died.  I couldn't get NASA to listen to me.  Outsider,  "not invented here",  and all that jazz.  But to this day I still show spaceflight crew escape concepts on my resume as something I consult in. 

GW


Oddly, perhaps, when you think about it, there is no escape system on an ordinary jet airliner.  So passengers wouldn't be at more risk really. In fact, I would expect the safety record to be better for the Skylon.  It would seem to avoid some of the dangers of rockets/the Space Shuttle...e.g. exploding rockets on the ground, bits falling off and hitting the fuel tanks etc.  If you avoid icy weather as well, is it going to be so dangerous?

What was your escape concept for the Space Shuttle?


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#15 2012-05-01 17:27:09

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Louis:

Both shuttle accidents showed pressure cabin separation from the rest of the debris (I witnessed this with my own eyes during Columbia's destruction,  right from my front yard).  Structurally,  the weak point was the cabin to cargo bay joint,  where the structure went from a closed tube to an open tube (no strength in the bay doors). 

If you take the spin off the pressure cabin (pressurized or not,  the crew should be in suits,  who cares if it is punctured in some way),  you can use the compartment between cockpit (two levels) and cargo bay as a sacrificial "heat shield",  with nothing more than a stabilizing drogue from the nose. 

Once the noisy hypersonics quiet down,  you are are low-supersonic decelerating toward M1/20kft max q,  and only dozens of seconds from impact.  You quickly blow the hatch,  and jump out on personnel chutes with an oxygen bottle.  No wings,  so we don't need the silly pole and tractor rocket motors. 

We have known since WW2 that crews were unable to bail out from spinning airplanes due to centrifugal forces.  In fact,  that problem was the original rationale behind ejection seats. 

But for a shuttle pressure cabin,  a de-spin drogue is simply more practical. 

We have also known since WW2 that bailout from a non-spinning airplane is easy.  Just don't do it above about M1 or thereabouts,  because of the nonsurvivable wind blast (known since the early 50's).  Which transonic point is some 20kft on the typical ballistic re-entry trajectory,  even for debris. 

GW

Last edited by GW Johnson (2012-05-01 17:30:42)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#16 2012-05-01 18:44:15

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

GW Johnson wrote:

Louis:

Both shuttle accidents showed pressure cabin separation from the rest of the debris (I witnessed this with my own eyes during Columbia's destruction,  right from my front yard).  Structurally,  the weak point was the cabin to cargo bay joint,  where the structure went from a closed tube to an open tube (no strength in the bay doors). 

If you take the spin off the pressure cabin (pressurized or not,  the crew should be in suits,  who cares if it is punctured in some way),  you can use the compartment between cockpit (two levels) and cargo bay as a sacrificial "heat shield",  with nothing more than a stabilizing drogue from the nose. 

Once the noisy hypersonics quiet down,  you are are low-supersonic decelerating toward M1/20kft max q,  and only dozens of seconds from impact.  You quickly blow the hatch,  and jump out on personnel chutes with an oxygen bottle.  No wings,  so we don't need the silly pole and tractor rocket motors. 

We have known since WW2 that crews were unable to bail out from spinning airplanes due to centrifugal forces.  In fact,  that problem was the original rationale behind ejection seats. 

But for a shuttle pressure cabin,  a de-spin drogue is simply more practical. 

We have also known since WW2 that bailout from a non-spinning airplane is easy.  Just don't do it above about M1 or thereabouts,  because of the nonsurvivable wind blast (known since the early 50's).  Which transonic point is some 20kft on the typical ballistic re-entry trajectory,  even for debris. 

GW


Well I think you better design the escape mechanism rather than me GW! LOL

I have always thought it's strange we don't give jet passengers a fighting chance of survival with parachutes.  I speak as someone who survived an engine failure on a Tristar. smile


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#17 2012-05-02 03:35:48

Glandu
Member
From: France
Registered: 2011-11-23
Posts: 106

Re: Reaction Engines

Louis, for most airplane crashes, 'chutes would not have saved the day. The most frequent scenarii are

_failed take-off(Concorde, Gonesse, 2001, less than 10 km from my home) : you are not high enough for a 'chute to save you.
_failed landing : everything is OK, you're going to the track, and crash.
_unexpected crash where you thought you could go, and in fact that damn mountain was higher.
_misinterpretation of the instruments(Rio-Paris crash in 2009, where even the crew did understand far too late that the ariplane was losing altitude quickly. Last sentences were "
_I don't believe it, we're gonna hit!
_I don't understand, what's happening?")

The only case where it could be useful would be a complete engine shut-off, with no engine recovery possible, above the ground. That's not a common scenario. There are 'chutes on military aircraft because they all share another scenario : shot down by the enemy. Scenario where 'chutes can save your life 50% of the time. Scenario that airliners are not supposed to share.

Spacecrafts, at least in the beginning, will be far smaller & less reliable. 'chutes there will be far more useful in case of failure, & failures will happen far more often. When I took this A320 to come back from Krakow 10 days ago, we were more than 100 inside. Giving 'chutes to more than 100 people, then having them jump from a limited number of doors, without getting eaten by the reactors? Well, better try to survive the crash.


"I promise not to exclude from consideration any idea based on its source, but to consider ideas across schools and heritages in order to find the ones that best suit the current situation." (Alistair Cockburn, Oath of Non-Allegiance)

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#18 2012-05-02 07:51:38

Rune
Member
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Reaction Engines

GW Johnson wrote:

Louis:

Both shuttle accidents showed pressure cabin separation from the rest of the debris (I witnessed this with my own eyes during Columbia's destruction,  right from my front yard).  Structurally,  the weak point was the cabin to cargo bay joint,  where the structure went from a closed tube to an open tube (no strength in the bay doors). 

If you take the spin off the pressure cabin (pressurized or not,  the crew should be in suits,  who cares if it is punctured in some way),  you can use the compartment between cockpit (two levels) and cargo bay as a sacrificial "heat shield",  with nothing more than a stabilizing drogue from the nose. 

Once the noisy hypersonics quiet down,  you are are low-supersonic decelerating toward M1/20kft max q,  and only dozens of seconds from impact.  You quickly blow the hatch,  and jump out on personnel chutes with an oxygen bottle.  No wings,  so we don't need the silly pole and tractor rocket motors. 

We have known since WW2 that crews were unable to bail out from spinning airplanes due to centrifugal forces.  In fact,  that problem was the original rationale behind ejection seats. 

But for a shuttle pressure cabin,  a de-spin drogue is simply more practical. 

We have also known since WW2 that bailout from a non-spinning airplane is easy.  Just don't do it above about M1 or thereabouts,  because of the nonsurvivable wind blast (known since the early 50's).  Which transonic point is some 20kft on the typical ballistic re-entry trajectory,  even for debris. 

GW

Question: wouldn't the hypersonic airflow shake the very non-aerodynamic broken cabin into complete destruction? Never mind the superheated air finding the thermally soft spots, wherever they are, and burning through them like a blowtorch, getting the heat into the airframe, the astronauts would be long dead plastered on the wall by then in this scenario. Unless you redesign the whole primary structure with designed failure points that result in a self-stabilizing detached cabin, or something. Also, how do you test that this works, never mind modeling it for design? You sacrifice a couple orbiters?


Rune. Just nit-picking, but I imagine these are the kind of things that went through their minds. smile


In the beginning the universe was created. This has made a lot of people very angry and been widely regarded as a "bad move"

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#19 2012-05-02 09:37:29

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Rune:

I've seen a lot of re-entering satellites,  and I watched Columbia re-enter in pieces,  although I didn't know it was Columbia until about 10 minutes later.  Thinking back on what I saw,  and watching the video footage others took over-and-over,  I pretty well figured out what I saw. 

The ship lost its wing to the foam impact damage at about M12 over the Texas-New Mexico border.  (It was photographed over New Mexico at M15 intact but streaming debris from an obviously-failing wing.)  It tumbled and immediately lost its other wing,  vertical fin,  and bay doors to the hypersonic wind blast. 

2-3 seconds later the windshield caved in,  ripping the top off the flight deck,  and the 4 astronauts there were ripped out from under their seat belts in pieces.  3000-5000 psf q does that.  No time to burn,  just blunt wind blast pressure forces.  Those 4 torn-apart astronauts were the body parts that rained down just east of Dallas,  a little cooked,  but not burnt. 

We knew about the vulnerability of the windscreen to direct hypersonic stream impingement when I was a grad student in 1973.  Found it in wind tunnel tests,  and found the narrow range of AOA where the stream safely jumps over the cockpit,  as a separated flow.  Lose attitude control,  you're dead. 

When it was over Dallas at about M6 or 7,  that's when I saw it from outside Waco,  Texas,  to my north about 100 miles slant range.  The heavy engine thrust structure had already separated.  It and the fuselage (cabin still attached) led the debris stream.  The wings were fluttering along behind,  along with the chunks of bay doors and the fin,  and a whole cloud of smaller pieces,  maybe 2 dozen or so.  The fuselage and thrust structure were tumbling.  I could not see them tumble,  but they were leaving characteristically-braided contrails. 

I watched it go eastward until the contrails dimmed as the hypersonics faded into "mere" supersonics.  Between Dallas and Tyler,  I saw the fuselage break up as a fan of pieces,  leaving the cabin tumbling alone and still mostly intact,  except for the lost flight deck roof.  A contact at NASA confirmed to me that the three on the mid deck were still alive at that point,  although I hope the gee-force pounding had beaten them unconscious.  That's the last I saw of it,  visually.

Seconds later the cabin decelerated to about M1/20kft,  and was crushed by the rapidly-rising wind pressures again.  My contact at NASA said that's when the 3 mid deck astronauts died by blunt force trauma,  not upon impact with the ground seconds later.  If stabilized so as not to tumble,  it would not have crushed like that. 

Clearly,  lots of the structures survived the re-entry in recognizable condition.  This includes uniform patches and plastic parts from the interior.  No,  this stuff doesn't burn up on re-entry the way all the "experts" always said it did all these years.  There isn't time to burn,  it decelerates quite rapidly.  The pieces literally heat-sink their way through reentry on a transient. 

As for crew survival,  you separate the cabin from the cargo bay with a shaped charge,  and stream an inflated drogue from the nose to take the spin off the cabin.  If there’s enough warning time,  the flight deck crew can evacuate down to the middeck.  Otherwise,  windshield failure and flight deck roof loss is very likely before the drogue can stabilize it.  As it slows to “mere” supersonic speed,  you blow the hatch.  All survivors on the mid deck have but seconds to jump before impact,  but that’s better than no chance at all. 

It was the same with Skylab in 1979.  Fragile thin-shell aluminum remained intact as one single radar return down to 40 nautical mile altitude,  about halfway through reentry (around M12,  just like Columbia).  Minutes later,  although the solar wings and telescope mount were gone,  the main body was still in one piece when it completed reentry just off the western Australian coast. 

It finally broke up over land at about M1/20kft,  while ballistically falling into rapidly rising q at low altitudes as the path angle quickly steepened downward.  Of 85-90 tons at reentry,  they picked up 75 tons of debris in Australia.  Nope,  these things most definitely do not "burn up". 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#20 2012-05-02 14:19:43

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Louis:

I went and looked at Reaction Engines' web page,  and crawled around a bit just looking.  Things have changed since I first ran across them a few years ago. 

Most or all of the essential engine component technologies are now funded development programs of this or that agency.  If these component technologies can be made to work about as thought,  then the system can really be built.  Like most web sites,  it's quite optimistic,  but I saw enough "meat" to know for sure it's "real",  meaning this thing might eventually fly.  They do have a long way to go proving all the engine components.  And then there's some airframe components that will have to be proven,  most notably the heat shield. 

A look at their web site was reminiscent of looking at XCOR Aerospace's site,  except Reaction Engines is fairly big by comparison.  Yet,  I know that XCOR's Lynx suborbital tourist spaceplane is "for real",  too.  You should go visit their site. 

I've sat in their Lynx mockup,  and it's simple enough even I could fly that spaceplane.  My contacts there tell me Lynx number 1 is being built this year on their hangar floor. 

XCOR is about 30 guys and gals in one hangar at the Mojave,  CA municipal airport.  They've made their living so far selling rocket engines with the life,  restart,  and maintenance characteristics one expects from FAA-certified aircraft engines.  They're definitely "for real",  too.  Watch them,  I think they'll impress you next year. 

Most of the rest of the flightline at that airport is owned by Burt Rutan / Scaled Composites.  Last time I saw Burt in person was 1985.  Didn't get to go visit him,  when I visited XCOR recently (who's looking for ramjet help from me). 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#21 2012-05-02 16:18:30

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,310

Re: Reaction Engines

GW Johnson wrote:

Louis:

I went and looked at Reaction Engines' web page,  and crawled around a bit just looking.  Things have changed since I first ran across them a few years ago. 

Most or all of the essential engine component technologies are now funded development programs of this or that agency.  If these component technologies can be made to work about as thought,  then the system can really be built.  Like most web sites,  it's quite optimistic,  but I saw enough "meat" to know for sure it's "real",  meaning this thing might eventually fly.  They do have a long way to go proving all the engine components.  And then there's some airframe components that will have to be proven,  most notably the heat shield. 

A look at their web site was reminiscent of looking at XCOR Aerospace's site,  except Reaction Engines is fairly big by comparison.  Yet,  I know that XCOR's Lynx suborbital tourist spaceplane is "for real",  too.  You should go visit their site. 

I've sat in their Lynx mockup,  and it's simple enough even I could fly that spaceplane.  My contacts there tell me Lynx number 1 is being built this year on their hangar floor. 

XCOR is about 30 guys and gals in one hangar at the Mojave,  CA municipal airport.  They've made their living so far selling rocket engines with the life,  restart,  and maintenance characteristics one expects from FAA-certified aircraft engines.  They're definitely "for real",  too.  Watch them,  I think they'll impress you next year. 

Most of the rest of the flightline at that airport is owned by Burt Rutan / Scaled Composites.  Last time I saw Burt in person was 1985.  Didn't get to go visit him,  when I visited XCOR recently (who's looking for ramjet help from me). 

GW


Do you know the guys at Armadillo, GW?  I like the look of their DIY rocket for Mars. Looks like something the Mars settlers might be able to build themselves after a few years.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#22 2012-05-03 17:23:02

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Louis:

No,  I've never met the Armadillo guys.  I went to their website and crawled around a bit,  including looking at their Stiga-2 movie. 

That test reminded me very strongly of the US Army Bumper-WAC test ca. 1950.  Stiga-2 was a high-performance single stage sounding rocket.  Bumper-WAC was a 2-stage rig made of a captured V-2 and an Army WAC-Corporal missile.  Bumper-WAC actually reached about 200 miles (300 km) up.  Same sort of profile.  Neither had active roll control. 

The ballute test was really intriguing.  It was clearly deployed and inflated in vacuum just after apogee.  I could see the air drag stabilizing the cluster somewhat,  just before the strap failed.  I have to wonder if the point mass of the nose cone bouncing around,  midway out the strap,  isn't why it failed. 

Myself,  I would have used separate ballutes for the main rocket body and the nose cone.  Straps are more durable without extra point masses banging around.  At least,  that's been my experience. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#23 2012-05-14 06:07:56

Impaler
Member
From: South Hill, Virginia
Registered: 2012-05-14
Posts: 286

Re: Reaction Engines

Assuming the Engine proves viable the proposed Vehicle should be extremely affordable, probably an Order of Magnitude over the ideal expendable Rocket targets (SpaceX).  The only downside I see is the relatively small payload size of 12 tons, about half of what current Heavy lift rockets can manage.  Assuming the vehicle can't practically be enlarged then I would see Skylon falling into more of a Tanker role delivering LOX & LH2 to stations and dry boosters in LEO, I bet it would be desirable from payload size and construction standpoint to make versions of the vehicle that replace the cargo bay and straddling LOX tanks with one continuous LOX tank, just size all the tanks such that the vehicle has the right ratio of remaining fuel to dispense to the delivery point.  I bet you could squeeze another ton or two of payload with that.

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#24 2012-05-14 10:44:11

Rune
Member
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Reaction Engines

GW Johnson wrote:

Rune:

I've seen a lot of re-entering satellites,  and I watched Columbia re-enter in pieces,  although I didn't know it was Columbia until about 10 minutes later.  Thinking back on what I saw,  and watching the video footage others took over-and-over,  I pretty well figured out what I saw. 

The ship lost its wing to the foam impact damage at about M12 over the Texas-New Mexico border.  (It was photographed over New Mexico at M15 intact but streaming debris from an obviously-failing wing.)  It tumbled and immediately lost its other wing,  vertical fin,  and bay doors to the hypersonic wind blast. 

2-3 seconds later the windshield caved in,  ripping the top off the flight deck,  and the 4 astronauts there were ripped out from under their seat belts in pieces.  3000-5000 psf q does that.  No time to burn,  just blunt wind blast pressure forces.  Those 4 torn-apart astronauts were the body parts that rained down just east of Dallas,  a little cooked,  but not burnt. 

We knew about the vulnerability of the windscreen to direct hypersonic stream impingement when I was a grad student in 1973.  Found it in wind tunnel tests,  and found the narrow range of AOA where the stream safely jumps over the cockpit,  as a separated flow.  Lose attitude control,  you're dead. 

When it was over Dallas at about M6 or 7,  that's when I saw it from outside Waco,  Texas,  to my north about 100 miles slant range.  The heavy engine thrust structure had already separated.  It and the fuselage (cabin still attached) led the debris stream.  The wings were fluttering along behind,  along with the chunks of bay doors and the fin,  and a whole cloud of smaller pieces,  maybe 2 dozen or so.  The fuselage and thrust structure were tumbling.  I could not see them tumble,  but they were leaving characteristically-braided contrails. 

I watched it go eastward until the contrails dimmed as the hypersonics faded into "mere" supersonics.  Between Dallas and Tyler,  I saw the fuselage break up as a fan of pieces,  leaving the cabin tumbling alone and still mostly intact,  except for the lost flight deck roof.  A contact at NASA confirmed to me that the three on the mid deck were still alive at that point,  although I hope the gee-force pounding had beaten them unconscious.  That's the last I saw of it,  visually.

Seconds later the cabin decelerated to about M1/20kft,  and was crushed by the rapidly-rising wind pressures again.  My contact at NASA said that's when the 3 mid deck astronauts died by blunt force trauma,  not upon impact with the ground seconds later.  If stabilized so as not to tumble,  it would not have crushed like that. 

Clearly,  lots of the structures survived the re-entry in recognizable condition.  This includes uniform patches and plastic parts from the interior.  No,  this stuff doesn't burn up on re-entry the way all the "experts" always said it did all these years.  There isn't time to burn,  it decelerates quite rapidly.  The pieces literally heat-sink their way through reentry on a transient. 

As for crew survival,  you separate the cabin from the cargo bay with a shaped charge,  and stream an inflated drogue from the nose to take the spin off the cabin.  If there’s enough warning time,  the flight deck crew can evacuate down to the middeck.  Otherwise,  windshield failure and flight deck roof loss is very likely before the drogue can stabilize it.  As it slows to “mere” supersonic speed,  you blow the hatch.  All survivors on the mid deck have but seconds to jump before impact,  but that’s better than no chance at all. 

It was the same with Skylab in 1979.  Fragile thin-shell aluminum remained intact as one single radar return down to 40 nautical mile altitude,  about halfway through reentry (around M12,  just like Columbia).  Minutes later,  although the solar wings and telescope mount were gone,  the main body was still in one piece when it completed reentry just off the western Australian coast. 

It finally broke up over land at about M1/20kft,  while ballistically falling into rapidly rising q at low altitudes as the path angle quickly steepened downward.  Of 85-90 tons at reentry,  they picked up 75 tons of debris in Australia.  Nope,  these things most definitely do not "burn up". 

GW

Ingenious though the idea may be, what I get out of it is mainly that you can't make a shuttle-like vehicle safe. Not as safe as a capsule. That "Lose attitude control,  you're dead", which would also be true for skylon I'm sure, will give old-fashioned capsules an edge forever, and the added point of a rocket escape system finishes the discussion, IMO. The capsule is just more fail-safe from the beggining, about the only system you really need working to survive a crash is an emergency parachute, or a rocket landing system. You can put both on, and add redundancy. Proof? Recently the russians had two soyuzes lose all control during reentry and executed ballistic flights (that is, they fell like rocks). They didn't even ground the craft while they worked the problem, and it didn't make the news, much less kill anyone.

And if someone tells me a skylon can be flown several times and reused, and therefore is more reliable, the same can be said of a proper reusable capsule. So if skylon is ever to be made into a manned transport, the payload I suggest is a independent capsule with an escape system. But, you know, skylon's proper use is to put bulk stuff like propellant cheaply on orbit in huge quantities and regularly, not to carry people in style, and that hopefully it can do.

And Impaler, 12 mT is nothing to be sneered at. You can't launch a lunar mission on that, sure, but you can service 99% of the satellite market (with the possible exception of the huge DOD GEO comm spy birds). Hell, most LEO satellites are just a couple of tons. Buy, I don't know, Fregat stages for the final insertion, and you can service anywhere up to GEO anything that is currently commercially built. Arianne V's 20mT to LEO payload mainly means they need to dual-launch big GEO birds and have room to spare for several secondary payloads to not waste room.


Rune. Oh, and thanks for the detailed description, GW. I actually listened to a classmate analyze the accident in class last year, but from the "why the leading edge failed" POV, nothing on what had happened afterwards.


In the beginning the universe was created. This has made a lot of people very angry and been widely regarded as a "bad move"

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#25 2012-05-14 11:56:10

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
Website

Re: Reaction Engines

Any spaceplane will resemble an airliner in its safety aspects.  It's just too hard to get a lot of folks out.  The more on board,  the worse this problem is.  So,  like airliners,  we will have to pay very careful attention to making them as safe as is humanly possible.  That's the way to build a passenger spaceplane. 

I think the choice between vertical launch rocket and horizontal spaceplane (one stage or two) depends really on the intrinsic value vs size of the cargo.  Using Atlas-5 and Falcon-Heavy as examples,  launching 25+ metric tons to LEO can be done for something like $1000-2500 per pound (as crude as this is,  $2000-5000/kg),  but only at the max payload capability of the vehicle. 

That last phrase is the key.  Some payloads will fall below that max flyable value for any launcher,  and it would be "wasteful" in a financial sense to launch them on rockets meant to haul much more.  The various spaceplane ideas could possibly have lower launch costs,  but the payload is a much smaller fraction of launch weight in systems like that. 

I think the spaceplanes will be carriers of smaller items (including crews if we really can make them safe enough).  The great massive things will fly mainly on vertical launch rockets.  So says "Cassandra".

As for launching propellants to LEO,  pre-tanked stuff comes in many sizes.  Big ones ought to fly on vertical launch rockets,   little ones perhaps on spaceplanes. 

Really "hard" tanked items could be shot into space by a light gas gun,  with a small solid motor for circularization.  That could be done for well under $100/lb.  Maybe even $10-20.  We'll see.  But your tanks (or other items) must withstand a 1000's-of-gees launch,  like artillery shells. 

GW Johnson


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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