Air-breathing rocket engine gets funding infusion

Jul 17, 2013 by Elizabeth Howell
A cutaway view of the proposed Sabre engine, which is being developed by Oxfordshire-based Reaction Engines. Credit: Reaction Engines

The technology, which sounds straight out of a science-fiction movie, has enough reality to it for the United Kingdom government to offer $90.62 million (£60 million), in stages, to a company looking to develop the engine.

The money will go to Oxfordshire-based Reaction Engines, which we've seen on Universe Today before. They're also developing an unpiloted and reusable spacecraft called Skylon, which is intended for low Earth orbit after leaving the planet from a conventional runway.

Skylon isn't flight-ready yet, but so far the project did pass a United Kingdom Space Agency technical assessment. If completed, the UK Space Agency says Skylon is just one of many vehicles that could use this engine, which is called Sabre.

"The unique engine is designed to extract the oxygen it needs for low atmosphere flight from the air itself, paving the way for a new generation of spaceplanes which would be lighter, reusable and able to take off and launch from conventional airport runways," the agency stated.

The money, stated Reaction Engines founder Alan Bond, will fund  "the next phase in the development of its engine and heat management technology." More specifically, this is what the company plans to use the funds for:

  • Engine technical design work;
  • Improving lightweight heat exchanger technology and manufacturing;
  • Performing and flight testing of engine components;
  • Doing a "ground demonstration" of the engine.

If all stays to schedule, Reaction Engines expects a Sabre prototype will be ready in 2017, with commencing in 2020.

The major goal of Sabre is to use hot air entering the engine to obtain the required oxygen for operations, rather than carrying the gas separately on board. The is supposed to switch to a "rocket mode" at 26,000 feet in altitude.

"This advantage enables a to fly lighter from the outset and to make a single leap to orbit, rather than using and dumping stages on the ascent – as is the case with current expendable rockets," the UK Space Agency stated.

Reaction Engines promises Skylon would give "reliable access to space" through carrying payloads of up to 15 tonnes, but at only 2% of the cost of more conventional launch vehicles—namely, rockets. It remains to be seen if they will achieve that cost goal, but the funding is welcome news nonetheless for the company.

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Aryeh_Z
3.1 / 5 (16) Jul 17, 2013
Great news!
GSwift7
2.2 / 5 (26) Jul 17, 2013
Don't get too excited yet. There are several engineering challenges that have had everyone stumped for decades on this. The US Air Force has been working on this for over 50 years.

The biggest problem is probably heat expansion, but there are many others.

The SR-71 Blackbird already has an engine design similar to what they're trying to do here, and it is complicated as hell. And that one doesn't even convert to a complete rocket type. The SR-71 engines are probably the most complex aircraft engines ever made, and the goal here is significantly more difficult.

I'll be surprised if they get a ground test model assembled, and I'll bet the guys over at Boeing and Lockheed are having a good laugh over this.

Even if they do get the engine to work, the rest of the skylon craft is doomed to fail to meet project goals. 200 flights on a single airframe is pure fantasy. They'll be re-building them after a few flights. The heat will eat them up.
NotAsleep
1.8 / 5 (5) Jul 17, 2013
A ramjet that only gets to 26,000 feet isn't that impressive... is it limited because rocket propulsion is required to achieve escape velocity? It seems like it would be more effective to fly higher before using your rockets
NotAsleep
4 / 5 (4) Jul 17, 2013
The SR-71 Blackbird already has an engine design similar to what they're trying to do here, and it is complicated as hell. And that one doesn't even convert to a complete rocket type. The SR-71 engines are probably the most complex aircraft engines ever made, and the goal here is significantly more difficult.

The SR-71's engine was (and is) complicated, yes, but not so complicated that it couldn't be solved with 1960s technology. If anything, better heat management technology and minimal military requirements should make it easier today than it was "back in the day."

Totally agreed that they'll be chewing through airframes much faster than they're claiming. Claims like this need to be made, though, if they expect to get funding...
supersubie
4.7 / 5 (13) Jul 17, 2013
The ESA did an extensive technology review on the pre cooler designed for these engines. Their assessment was that the pre cooler worked as stated and solved the hardest technological challenge these engines were facing and that they could see no major hurdles in the proposed engine designs. I have a lot of confidence in this company and in what it plans to do. Its about time we had a major breakthrough in propulsion systems. If this does work it will be a massive game changer in terms of our ability to cheaply and afford ably enter space.
islatas
3.4 / 5 (11) Jul 17, 2013
Why does the airframe need to be subjected to the heat? How many flights did the US space shuttles get out of each airframe before they required replacement?

I also think it's silly to assume that since it was complicated in the 50's and 60's it's not possible to do better now...60 years later with enhanced material understanding, enhanced materials, better engineering modelling, etc.
NotAsleep
3.8 / 5 (5) Jul 17, 2013
Why does the airframe need to be subjected to the heat? How many flights did the US space shuttles get out of each airframe before they required replacement?

NASA's space shuttle had the advantage of "industrial strength" booster rockets to launch the shuttle into space. The bottom was covered in heavy ceramic materials that likely wouldn't be feasible on a spacecraft that doesn't shed its booster-stage weight. Granted, heat management technology has progressed but it would be astonishing if it's progressed far enough to allow a fully self-sufficient air/spacecraft to be reused 200 times without needing major overhaul. The craft that Skylon is proposing is mostly special because it'll be the first "self contained" LEO craft designed
Neinsense99
2.9 / 5 (17) Jul 17, 2013
A ramjet that only gets to 26,000 feet isn't that impressive... is it limited because rocket propulsion is required to achieve escape velocity? It seems like it would be more effective to fly higher before using your rockets

That's 26,000 feet without needing internally-carried oxidizer, compared to 0 feet without for all other orbit-capable launch vehicles. Altitude matters, but more important is the speed. This vehicle is not intended to launch vertically and overall design and flight plans need to be considered.
NotAsleep
2.3 / 5 (6) Jul 17, 2013
That's 26,000 feet without needing internally-carried oxidizer, compared to 0 feet without for all other orbit-capable launch vehicles. Altitude matters, but more important is the speed. This vehicle is not intended to launch vertically and overall design and flight plans need to be considered.

Many aircraft can fly over 26,000 feet without oxidizer. Ramjets allow it to fly even higher without need of an oxidizer.. significantly higher, in fact, than 26K feet.

And I should say I just caught myself speculating that this is a ramjet based on how it looks... true ramjets can't take off from a dead stop so it would reason to believe this is either some sort of hybrid or a new engine type altogether
Eikka
3.3 / 5 (14) Jul 17, 2013
The SR-71 Blackbird already has an engine design similar to what they're trying to do here


No it doesn't. The SR-71 engine is a rather ordinary turbojet engine with a continuously operating afterburner.

http://en.wikiped...tney_J58
GSwift7
2.5 / 5 (22) Jul 17, 2013
The story here says 26 k feet, but all other sources say 26 km, which is 85 k feet, and is a more realistic number for a space plane. 26 k feet is nothing.

yes, but not so complicated that it couldn't be solved with 1960s technology


lol, the original concept for the Sabre engine is from the 1950's. The reason it was never built is that you don't really end up gaining much, if anything, versus a normal rocket. Don't forget that it costs you drag when you are scooping up and compressing air.

I suspect this is going to end just like Hotol, which was Mr Bond's previous failure. By the time they got to the design phase of Hotol, none of the original grand claims were going to come true. They were making the same kind of claims then as they are now. The payload, for example is wishfull thinking, as is the number of flights per airframe and the short turn around time for launches.

If you could match the claims, it would be great, but I don't think they can.
JohnGee
2.3 / 5 (12) Jul 17, 2013
A ramjet that only gets to 26,000 feet isn't that impressive... is it limited because rocket propulsion is required to achieve escape velocity? It seems like it would be more effective to fly higher before using your rockets

Getting to orbit isn't just about going up. You have to go horizontal as well. The skylon would have quite a bit more horizontal velocity than your typical rocket at 26km.

I'm assuming whatever they would get out of making the skylon go a little higher isn't worth complicating the engine any further, or maybe it adds so much weight it is a net loss.
vertex
2.5 / 5 (8) Jul 17, 2013
The vehicle design is for a hydrogen-powered aircraft that would take off from a conventional runway, and accelerate to Mach 5.4 at 26 kilometres (16 mi) altitude using atmospheric air before switching the engines to use the internal liquid oxygen (LOX) supply to take it to orbit.

....

Skylon could deliver 15 tonnes (33,069 lb) to a 300 kilometres (186 mi) height or 11 tonnes (24,251 lb) to an 800 kilometres (497 mi) altitude.

-Wikipedia
GSwift7
2.2 / 5 (17) Jul 17, 2013
No it doesn't. The SR-71 engine is a rather ordinary turbojet engine with a continuously operating afterburner


That's not correct at all. The engine itself isn't what made the SR-71 unique, just like the Sabre here. The operation of the J58 engine in the SR-71 was nothing like its use in other aircraft. The air inlet spike mechanism is very similar to the 'air cooler' in the Sabre. In fact, they are probably just barely getting around patent laws with Lockheed by changing the name and description of how it works. The spike arrangement in the SR-71 did the exact same thing they're trying to do here. They call it a cooler, but what they're really doing is compressing the air and slowing it down to sub-sonic speeds (cooling it). Those concentric cylinders of increasing size behind the spike in the Sabre are probably shock wave deflectors which accoustically cool the air just like the SR-71 intake did.

http://en.wikiped...lackbird

"air inlets" section
TheGhostofOtto1923
2.2 / 5 (20) Jul 17, 2013
The SR-71 Blackbird already has an engine design similar to what they're trying to do here
No its not.
The SR-71 engines are probably the most complex aircraft engines ever made
Not even close.
http://www.abovet...2563/pg1

"The J58 was initially developed for the US Navy to power the planned version of the Martin P6M jet flying boat...It was the first engine to be able to operate on afterburner for extended periods of time..."

-Many more advanced and more complex since.

The J-58 produced 32,000 lb
The Raptor'sF119-PW-100 engines pump out 35,000 pounds of thrust each
http://science.ho...tor4.htm

I'll be surprised if they get a ground test model assembled, and I'll bet the guys over at Boeing and Lockheed are having a good laugh over this
I'll be surprised if you start checking your posts for empty hyberbole.
TheGhostofOtto1923
2.9 / 5 (25) Jul 17, 2013
In fact, they are probably just barely getting around patent laws with Lockheed by changing the name and description of how it works
A moveable spike does not in any way resemble an active liquid helium precooler.

"The air from the intake (blue) is shown going though the Pre-cooler and into the compressor. The cooling is achieved with helium (green) that has been itself cooled by HX4 using the liquid hydrogen fuel (purple). Once it has left the Pre-cooler the helium is further heated in HX3 by the products of the Pre-burner to give it enough energy to drive the turbine and the liquid hydrogen (LH2) pump."
http://www.reacti...rks.html

-Stop turbopumping bullshit.
probably shock wave deflectors which accoustically cool the air just like the SR-71 intake did
Probably?? Well theyre not.

Instead of guessing and making things up why dont you do a little research?
GSwift7
2.3 / 5 (22) Jul 17, 2013
Otto, you're a trip. I'm devastated that some guy on a forum called abovetopsecret dot com disagrees that the SR-71 engine was the most complex aircraft engine ever built. It's true that the turbo prop engine he picked has a lot of moving parts, but it's a matter of opinion whether that makes it the most complex. I think the supersonic speeds, custom fuel and synthetic materials invented just for the SR-71 intake makes it the most complex ever built. That prop engine was just a bunch of cylinders strapped together to make a bigger version of existing turbo props. I guess everyone can have an opinion. Go figure.

I really don't see why you get so worked up when someone doesn't think life is like a comic book fantasy.

I think Bond is a con artist, sucking up public money for projects he knows cannot ever be completed as advertised. You can disagree if want, and I'll still love you man.
freeiam
2.4 / 5 (13) Jul 17, 2013
...I'll be surprised if they get a ground test model assembled, and I'll bet the guys over at Boeing and Lockheed are having a good laugh over this.

I hope they do, that will make the UK the number one in space in the near future.
Rolls-Royce isn't laughing though. Perhaps you know that the UK has a long history building jet engines.

...Even if they do get the engine to work, the rest of the skylon craft is doomed to fail to meet project goals. 200 flights on a single airframe is pure fantasy. They'll be re-building them after a few flights. The heat will eat them up.

No it won't. Did you hear of carbon fibre and ceramics?
TheGhostofOtto1923
2.4 / 5 (18) Jul 17, 2013
some guy on a forum called abovetopsecret dot com
Trip sir? You choose to disregard obvious facts because you dont like where they come from??
I think the supersonic speeds, custom fuel and synthetic materials invented just for the SR-71 intake makes it the most complex ever built
Not true. Obviously. This was only an early example of a number of afterburner engines. It was designed without computer modeling. The raptors engines develop more thrust in a lighter package with vectored thrust.

The engines they used in the phantom were more complex than the J58. Big and black and spooky do not necessarily equate with complex do they?

I really don't see why you get so worked up
Well its because you spout crap and this offends me. You continue to post it and I will continue to demonstrate.
I think Bond is a con artist
How would you know? You didnt even know the movable spike on his engine was for closing off the intake in rocket mode. Hahaha more crap.
TheGhostofOtto1923
2.1 / 5 (16) Jul 17, 2013
J58 (SR71)
Type: afterburning turbojet with compressor bleed bypass
Length: 17 ft 10 in (5.44 m) (an additional 6 in (15 cm) at max. temp.)
Diameter: 4 ft 9 in (1.45 m)
Dry weight: approx. 6,000 lb (2,700 kg)
Components:
Compressor: 9-stage, axial flow, single spool
Combustors: 8 can, annular
Turbine: two-stage axial flow

J79-GE-17 (F4 Phantom)
Type: Afterburning turbojet engine
Length: 17.4 ft (5.3 m)
Diameter: 3.2 ft (1.0 m)
Dry weight: 3,850 lb (1,750 kg)
Components:
Compressor: 17-stage axial compressor with variable stator vanes
Combustors: cannular
Turbine: 3-stage

-See? The phantom had more parameters to satisfy. Of course it was a more complex design. Re the J58 design philosophy:

"The chemical ignition was chosen instead of a conventional igniter due to reliability reasons and to LOWER the number of mechanical parts..."
sage101
2.8 / 5 (9) Jul 17, 2013
The topic in above comments is so crazy that after years of viewing phys.org l've gone to the trouble of creating an account so as to comment.

Its like the author of the article says, the technology sounds straight out of science fiction. Why?
Because it mimics closely the pattern found in sci-fi stories- 1 or 2 improbable sounding technologies ie ftl travet, time machine, with the rest of the story hanging from it.

As found in the Sabre engine. Such an engine could have been developed long ago, except for one thing: the air cooling technology. This is the improbable element I mentioned from the sci-fi analogy- just like the analogy the rest of the technology depends on it.(yes I read it passed government testing.)

So the engines now receiving gov't funding and people are commenting on the technology-but the comments are crazy!
Its like they were commenting on the realism of the star trek movie, and ignored the ftl & transporter technologies but focused on their clothes!
sogley
4.1 / 5 (9) Jul 17, 2013
I agree with sage101. Comparisons with the SR-71 and other aircraft are misleading because they employ different technology. The SR-71 achieves its speed with a ramjet, whilst the X51-A uses a scramjet. The SABRE engine in Skylon is very different because it uses a pre-cooled jet engine. It is the heat exchanger, capable of cooling the air flow from 1000°C to -150°C in 1/100th second, which is the enabling technology. This heat exchanger neatly cushions the jet engine from the ever increasing hot air intake - the jet engine doesn't even know what speed the plane is flying at (well, apart from exhaust emissions). It is presented with compressed air at a constant temperature, so if it works at 0 mph, it will work at 4,000 mph. There are, of course, other engineering challenges, such as the stability of the aircraft at high speeds, but the complexity of the engine is not one of them.
lengould100
2.8 / 5 (5) Jul 17, 2013
From the wiki articles on the SR-71 -- http://en.wikiped...lackbird

"The maximum speed was limited by the specific maximum temperature for the compressor inlet of 800 °F (427 °C). 1990s studies of inlets of this type indicated that newer technology could allow for inlet speeds with a lower limit of Mach 6."

Since at 29 km altitude, speed of sound drops to about 660 mph, this technology will be limited to about 4000 mph, or about 1/4 to 1/5th of orbital velocity. So an air-breathing engine capable of mach 6 is capable of reaching only a small part of the performance required for orbit. Then the question is, is the carrying of the added engine systems (complexity and mass) worth the fairly modest contribution to total velocity?

Perhaps not.
lengould100
5 / 5 (1) Jul 17, 2013
Especially when you consider the efforts which must then be made to protect such exposed parts of the craft as engine air intakes etc. from damage on re-entry. (particularly added mass). I can see the logic of developing this technology for high-speed point-to-point travle here on earth, esp. when hydrogen fueled, but am not convinced of the logic for travel to orbit. (Nor esp. the Virgin / Rutan strategy of a very low-speed moderate-altitude takeoff. IMHO never makes orbit due to limited mass which mothership can possibly carry.)
skip181sg
5 / 5 (2) Jul 18, 2013
GSWIFT7 - So AFAIK haven't they already test fired the prototype 100 times? So they have an engine right? Thats the SABRE

And as far a Skylon is concerned Alan Bond has already been quoted as saying that the technology for the frame and skin is already avail;able so nothing needs to be invented. Also that re-entry will not be like a Shuttle where they are essentially 'air breaking' at 22,000km/hr so the heat generation will not be anywhere near as great.
skip181sg
5 / 5 (2) Jul 18, 2013
Why does the airframe need to be subjected to the heat? How many flights did the US space shuttles get out of each airframe before they required replacement?

I also think it's silly to assume that since it was complicated in the 50's and 60's it's not possible to do better now...60 years later with enhanced material understanding, enhanced materials, better engineering modelling, etc.


The Shuttles did not get many. How many Shuttles were there? How many launches per year? And they retired them ahead of schedule right? Not a good comparison
meBigGuy
3 / 5 (5) Jul 18, 2013
As soon as there is air enough to produce heat, the engines can produce thrust for a controlled descent. Why would anyone compare this to a space-shuttle or other unpowered reentry vehicle?
GSwift7
1.9 / 5 (13) Jul 18, 2013
Then the question is, is the carrying of the added engine systems (complexity and mass) worth the fairly modest contribution to total velocity?

Perhaps not.


That's why all previous attempts of this technology tree have been abandonded. You're exactly right, and all the major AE companies agree with you.

So AFAIK haven't they already test fired the prototype 100 times? So they have an engine right?


No, they've demonstrated the heat exchanger of the air intake system. They haven't even constructed a fully assembled air intake system. They just tested the ability of the heat exchanger to move calories over time. They supposedly require at least 200 million more in funding just to construct a test engine. I doubt such funding will ever be approved, and I doubt 200 is enough. Bond has a history of this kind of stuff, as witnessed in ALL of his previous projects. Vapourware, nothing more. Paper tigers do not hunt.
GSwift7
2.2 / 5 (15) Jul 18, 2013
As soon as there is air enough to produce heat, the engines can produce thrust for a controlled descent. Why would anyone compare this to a space-shuttle or other unpowered reentry vehicle?


I'm too tired to research it, but I would assume that the plan is to only take enough fuel for the launch, so the reentry would be un-powered. It would be a waste to carry fuel you don't need. I think I'm probably safe in that assumption, even without looking it up.
PhotonX
5 / 5 (5) Jul 18, 2013
Why does the airframe need to be subjected to the heat? How many flights did the US space shuttles get out of each airframe before they required replacement?
The rough average is 30. There were a total of 119 powered flights, not counting the five unpowered landings by the test bed Enterprise. While there were five shuttles, one was built as a replacement for Challenger. Two were destroyed in flight, though neither of those were due to a primary cause of airframe failure per se.
.
So, the total shuttle fleet had only 3/5th the number of flights projected for a single Skylon airframe. Unrealistic? I don't know, but the Space Shuttle isn't a good comparison since they never approached this number, and never dealt with an airframe failure because of all the other faults of the system.
sogley
5 / 5 (5) Jul 18, 2013
So an air-breathing engine capable of mach 6 is capable of reaching only a small part of the performance required for orbit. Then the question is, is the carrying of the added engine systems (complexity and mass) worth the fairly modest contribution to total velocity?

Yes, it is, it makes single stage to orbit possible.

Launching into low earth orbit requires a velocity of 17,500 mph but a rocket has to be capable of more than that to compensate for gravity and drag losses. But flying to 4,000 mph at 26 km in jet engine mode overcomes 80% of the gravity and drag losses. This means jet engine mode effectively provides one third of the required delta-v.

That's why all previous attempts of this technology tree have been abandoned.

No, that's not why all previous attempts have been abandoned. It's because no one has figured out a way of making a small enough pre-cooler that doesn't clog up with frost until now.
TheGhostofOtto1923
1.3 / 5 (12) Jul 18, 2013
@sogley
The sr71 achieves it's speed with a ramjet or something I don't know so I'll guess
It's engines are turbofan per my post. Can't you fucking read?
TheGhostofOtto1923
1.3 / 5 (12) Jul 18, 2013
I'm too tired to research boohoo
Naw you're too lazy I think. You would rather write than read. Your fingers have energy to type here but not in google?
Reentry would be UN-powered
Well you guessed right for once:

"During re-entry, which occurs at an altitude between 90 to 60km the heat is radiated away from the hot aeroshell. Heat is prevented from entering the vehicle by layers of reflecting foil and the low conductivity shell support posts. Liquid hydrogen is evaporated in the main tanks, passed through thermal screens to intercept the small residual heat leak and then vented overboard."

-Took me 5 minutes by typing 'skylon' in google.
sogley
5 / 5 (4) Jul 18, 2013
It's engines are turbofan per my post. Can't you fucking read?

Of course I can read, there's no need to be rude.

According to Wiki, "the engine can be thought of as a turbojet inside a ramjet" and "at higher speeds, the turbojet largely ceases to provide thrust." Are you saying Wiki is wrong? So, the turbojet gets it off the ground and the ramjet provides the higher speeds, roughly speaking. Without the ramjet it wouldn't go as fast as it does, which is why I said "the SR-71 achieves its speed with a ramjet." Again in Wiki, "Inlet cones are primarily used on ramjets, such as the turboramjets of the SR-71" and "The SR-71's Pratt & Whitney J58 engines act as turbojet-assisted ramjets at high speeds."
TheGhostofOtto1923
1.4 / 5 (11) Jul 18, 2013
Well thanks for something I could google.
http://mywiki.eve...tney_J58

-My apologies.
maxb500_live_nl
1.8 / 5 (5) Jul 18, 2013
I like the concept. But the Space Shuttle also was designed to greatly reduced costs and it turned out to be the most expensive vehicle in history. The Skylon is supposed to go completely into orbit and come back. Requiring the entire craft to have a heat shield, requiring massive overhauls to check for defects and replacement of the heat shield tiles (or what ever they will use as a heat shield). Requiring long overhaul periods no matter what they promise. If you have seen the video concepts of dozens of Skylons in space you know these guys behind it are somewhat unrealistic. And that leaves an engine that needs to be proven. And it leaves a very large craft that can barely launch 15 tons into low earth orbit. While many satellites need extra stages to reach GEO orbit. Yet the payload bay doesn`t allow for this.

Could it work: probably. But it will be far more expensive and unpractical then they hope it will be. But the technology development is great. Perhaps even to use in planes.
NotAsleep
5 / 5 (2) Jul 18, 2013
The SABRE engine in Skylon is very different [from SR-71 & X-51]because it uses a pre-cooled jet engine. It is the heat exchanger, capable of cooling the air flow from 1000°C to -150°C in 1/100th second, which is the enabling technology.

I'm assuming you pulled your information from:
http://www.reacti...ech.html

These are incredible claims... I'm having a hard time wrapping my head around how you cool air that much in that short a time consistently while traveling over mach 5 and without damaging your heat exchanger. As an engineer, I would consider this a lifetime achievement if I were able to pull it off and see it in operation
Eikka
3.7 / 5 (6) Jul 18, 2013
The SABRE engine in Skylon is very different because it uses a pre-cooled jet engine.


The SABRE doesn't even have a jet-engine in the sense of a conventional turbojet. It has a turbo-compressor that feeds the cooled-down air into a rocket engine nozzle.

It has a jet in it, because the operation of the cooler and turbopump requires more liquid hydrogen than the rocket engine can consume with the amount of oxygen it has, so the excess hydrogen is burned off in a ramjet with the air that spills over from the intake cooler. The engine takes off basically by using rocket power, and switches to a combination of rocket and ramjet once it gets some speed, then back to rocket power once it's going fast enough.

At no point does the engine run like a regular jet engine, or like the SR-71's turbojet, because it isn't one.
Eikka
3.5 / 5 (8) Jul 18, 2013
But the Space Shuttle also was designed to greatly reduced costs and it turned out to be the most expensive vehicle in history.


That's because the space shuttle was designed by a committee that was spending other people's money, so of course everyone wanted everything in it, and they made a bunch of very basic errors, like designing the heat shield tiles to be unique, so each tile has to be specifically made to fit its place, and there's 35,000 of them.

The costs also ran up because they split the work over dozens of different companies that each manufactured some part of the whole, as a part of a government stimulus plan, which ended up causing lots of integration problems.
TheGhostofOtto1923
1.3 / 5 (12) Jul 18, 2013
The space shuttle was a military system designed to launch from a dedicated and hardened facility at vandenberg (built, never used) and sized to launch spysats and ISS components.

Cutting edge miltech is always expensive as it is often conceived with anticipated tech which is projected to be developed during the course of design, construction, and use.

NASA is and always has been a military agency. Recon is a military function.
Eikka
3 / 5 (4) Jul 18, 2013
and sized to launch spysats and ISS components.


Designed, but not actually built. The final result was 20% overweight, so it couldn't actually launch the military payloads specified for.
Eikka
3 / 5 (4) Jul 18, 2013
The other odd thing about the space shuttle is that it carries the large main engines to orbit, even though it never uses them there. Once the big yellow tank drops off, the shuttle switches over to the OMS. The Soviet-built Buran shuttle didn't, because it's just dead weight. That's why the Buran had a higher payload capability than the Space Shuttle.
islatas
5 / 5 (3) Jul 18, 2013
The Shuttles did not get many. How many Shuttles were there? How many launches per year? And they retired them ahead of schedule right? Not a good comparison


You make that statement yet don't even know how many shuttles there were or how often they flew? Really? It's a perfectly good comparison. The shuttles are the ONLY example of a reusable airframe for a spaceship in history with a long (over 30yr) history of use. The skylon plans to be one of the many future reusable spaceships. I replied to a statement that airframes can't last more than a few flights. The space shuttles say "Wrong". They were not retired early. The replacements were cancelled in design phase in the 90s. The shuttle was built off of tech that's 40 years + old now and performed admirably for the first of its breed.

The point stands. New tech and materials will yield a substantially better spacecraft with enhanced durability. Whether or not the Skylon is the ship to do it...
islatas
5 / 5 (2) Jul 18, 2013
...and they made a bunch of very basic errors, like designing the heat shield tiles to be unique, so each tile has to be specifically made to fit its place, and there's 35,000 of them.


What is your solution? The geometry of the craft is variable along the length and width and the tile tolerances are not. There are 7 different materials used in different areas and the tile thickness varies; both based on heat dissipation demand, durability, etc and variation driven by cost and weight. The tile sizes were limited. 24,300 unique tiles out of 31,000 on the shuttle. The whole system weighed about 8,600 kg for over 1,100 sq meters. Basic problem, right? So I'm assuming you have a basic solution using 1970's tech? Let's hear it.
freeiam
1.4 / 5 (9) Jul 18, 2013
...and they made a bunch of very basic errors, like designing the heat shield tiles to be unique, so each tile has to be specifically made to fit its place, and there's 35,000 of them.


What is your solution? The geometry of the craft is variable along the length and width and the tile tolerances are not. There are 7 different materials used in different areas and the tile thickness varies; both based on heat dissipation demand, durability, etc and variation driven by cost and weight. The tile sizes were limited. 24,300 unique tiles out of 31,000 on the shuttle. The whole system weighed about 8,600 kg for over 1,100 sq meters. Basic problem, right? So I'm assuming you have a basic solution using 1970's tech? Let's hear it.


The solution now is to use a ceramic coating. It can be checked easily with röntgen or maybe even electrically.
TheGhostofOtto1923
1.3 / 5 (12) Jul 18, 2013
The final result was 20% overweight, so it couldn't actually launch the military payloads specified for.
But luckily spysats got smaller and lighter. Who knew? (they did)
http://www.nytime...ite.html

-This is how the very most advanced weapons systems in the world are produced.
The other odd thing about the space shuttle is that it carries the large main engines to orbit, even though it never uses them there. Once the big yellow tank drops off, the shuttle switches over to the OMS
Yeah and its too bad all those tanks were discarded when they could have been used to build something really substantial in orbit, if only the shuttle had had the engines to haul them around... no wait! Maybe we have an answer-

Weapons systems often contain contingencies which are not actually ever used but the decision whether to include them or not must be made very early in design. $4 billion was spent on the vandenberg facility.
sogley
5 / 5 (3) Jul 18, 2013
The SABRE engine in Skylon is very different because it uses a pre-cooled jet engine.

The SABRE doesn't even have a jet-engine in the sense of a conventional turbojet. It has a turbo-compressor that feeds the cooled-down air into a rocket engine nozzle.

Yes, you're right, I made the mistake of thinking that an engine with a compressor was a jet engine. I should have called it an 'air breathing rocket engine'.
baudrunner
1.5 / 5 (8) Jul 18, 2013
..the Space Shuttle also was designed to greatly reduced costs and it turned out to be the most expensive vehicle in history
One wonders, however, whether over the long term the reusable space shuttles were cheaper than disposable vehicles would have been for the 44 missions that they flew to assemble the ISS. And that cost is not a bad thing, since it can always be attributable to employment and economic activity withing a non military framework. If you want to complain about cost, complain about the cost of waging wars, in monetary and human terms. There's no argument.
The solution now is to use a ceramic coating
Not a chance. Different parts of the shuttle experienced different thermal effects during re-entry, meaning that a single coating will crack because of the response to those temperature differences over the surface of the craft. That's why they used tiles in the first place. And even so, tiles damaged during re-entry needed replacing after every flight.
ScottyB
2.3 / 5 (3) Jul 19, 2013
more info with a short video
http://www.bbc.co...23332592
Eikka
3.9 / 5 (7) Jul 19, 2013
What is your solution?


Change the geometry to mind the manufacturability and replaceability of the heat shield tiles. Obviously.

It's not given that the space shuttle had to be that shape - it's rather more likely that they built it that way because it was easier to design using tools of the era. When you design with a slide ruler, you get characteristic designs, because you rely largely on readily solved tables and charts, or you just wing it about so. The effect is similiar to how cars suddenly became really boxy when computer aided design took hold in the late 70's but the computer systems weren't powerful enough to solve complex shapes.

One problem of the Space Shuttle was that it's too small, or rather, too dense. It falls down like a brick, and that's why it heats up so much as it enters the denser parts of the atmosphere. The Skylon spaceplane is intended to be larger in volume, so it comes down slower and doesn't need such extensive and expensive heat shield.
baudrunner
1.3 / 5 (12) Jul 19, 2013
One problem of the Space Shuttle was that it's too small, or rather, too dense. It falls down like a brick, and that's why it heats up so much as it enters the denser parts of the atmosphere. The Skylon spaceplane is intended to be larger in volume, so it comes down slower and doesn't need such extensive and expensive heat shield.
Good Lord! Why do people with no science education write on this site? Everything falls at 32'/sec^2, regardless of size or density. The shuttle doesn't "fly" back, it falls, and eventually the atmosphere brakes it enough to allow it to glide to a landing. The Skylon spaceplane is going to be subject to the same gravity that brought the shuttle down, you know. And, by the way, it is a given that the space shuttle had to have that shape. It's the ultimate compromise for launch and reentry purposes. All competing designs, specifically the Soviet one, used the same configuration, because it is the ideal one. Stop knocking the space shuttle.
Eikka
3.7 / 5 (9) Jul 19, 2013
Good Lord! Why do people with no science education write on this site?


I don't know. Maybe you do?

There is atmosphere even where the ISS is. It just doesn't stop abruptly - spacecraft fall down through an atmosphere that is growing continuously thicker the further they descend, and a less dense object, which means it has a lower ballistic coefficient, slows down sooner and experiences less drag force and heating as a result because it enters the really thick part of the atmosphere at a lower speed.

That is an actual design goal of the Skylon space plane. Google it up if you don't believe me.

The Space Shuttle isn't any sort of "ultimate compromize". It's just what the engineers could manage given the tools, the skill, the money, the time and the specifications they had to work with. It's probably not even the best that they could have managed.
Eikka
3.3 / 5 (7) Jul 19, 2013
All competing designs, specifically the Soviet one, used the same configuration, because it is the ideal one.


a) The Soviets basically copied the design to save themselves the effort.
b) The Skylon is using a similiar design, except most of it is empty because the fuselage is 85% of fuel in mass at the start of the flight, and nearly empty when it de-orbits. It's really like a feather to a brick compared to the Space Shuttle, and that's why it's able to do without the special heat shelding tiles.

sogley
3.5 / 5 (8) Jul 19, 2013
The Skylon is using a similiar design, except most of it is empty because the fuselage is 85% of fuel in mass at the start of the flight, and nearly empty when it de-orbits. It's really like a feather to a brick compared to the Space Shuttle, and that's why it's able to do without the special heat sheilding tiles.

Would a possible answer have been to incorporate the Space Shuttle's external fuel tank into the Orbiter and make it less dense? (This would, of course, make the landing gear more heavy and the extra weight may have been too much.)
TheGhostofOtto1923
1.9 / 5 (14) Jul 20, 2013
Good Lord! Why do people with no science education write on this site?
I don't know. Maybe you do?
Always best to provide an excerpt for nose-rubbing:

"Because of the low ballistic coefficient, Skylon would be slowed at higher altitudes where the air is thinner. As a result, the skin of the vehicle would only reach 1,100 Kelvin (K). In contrast, the smaller Space Shuttle was heated to 2,000 K on its leading edge, and so employed an extremely heat-resistant but fragile silica thermal protection system. The Skylon design does not require such a system, instead opting for using a far thinner yet durable reinforced ceramic skin. However, due to turbulent flow around the wings during re-entry, some parts of Skylon would need to be actively cooled"
incorporate the Space Shuttle's external fuel tank into the Orbiter and make it less dense?
Ahaahaaaa
johnhew
2.3 / 5 (6) Jul 20, 2013
why is the engine curved?
Eikka
3.3 / 5 (7) Jul 21, 2013
Would a possible answer have been to incorporate the Space Shuttle's external fuel tank into the Orbiter and make it less dense?


The specific impulse (basically, fuel economy) of the Space Shuttle engines is so poor that the payload fraction would have been basically nothing if you did that. Adding mass to the orbiter increses the amount of fuel needed to get it to orbit exponentially, which is why the main fuel tank is dropped once it's empty.

One of the proposed shuttle designs was actually a fairly large delta-wing, which would have been mostly empty and would have provided them with enough surface area to minimize air heating, but would have been more cumbersome on the launchpad.

sogley
5 / 5 (7) Jul 21, 2013
why is the engine curved?

The Skylon body itself provides some of the lift in air-breathing mode and to do that it flies at a slight angle. The SABRE engine inlet has to point forwards in air-breathing mode but in rocket mode, the thrust must be aligned with the centre of gravity. Hence the engine is curved.
TreefrogUK
5 / 5 (5) Jul 21, 2013
@ GSwift7:

You seem to have a knee-jerk reaction to this project, with many 'supposes' and 'thinks' and 'probablys' in your comments rather than reasoned arguments. As well as your stated reluctance to research the topic.

HOTOL was the original concept but suffered from many design flaws, Skylon is starting from a clean sheet of paper with effectively only the engine concept carried through - and Alan Bond had to find a way to circumvent the patents he'd originally written for the RB545 engine!

May I direct you to reactionengines.co.uk where there is a wealth of technical details, including ESA's assessment of the technology - I'm sure that you will agree that they are far better placed than you or I to evaluate the feasibility of this project. You might also like to view a documentary on youtube about it - 'Three Rocketeers'

TheGhostofOtto1923
1 / 5 (12) Jul 21, 2013
why is the engine curved?

The Skylon body itself provides some of the lift in air-breathing mode and to do that it flies at a slight angle. The SABRE engine inlet has to point forwards in air-breathing mode but in rocket mode, the thrust must be aligned with the centre of gravity. Hence the engine is curved.
You're guessing again soggy. Is your conjecture also true for any of the other craft which have been designed in the same configuration but without the curved engines?

I think it might have something to do with directing hot exhaust away from the fuselage, but of course I would be guessing.
sogley
4.5 / 5 (8) Jul 21, 2013
You're guessing again soggy.

If you look in the following file you will see that the angle of incidence varies between 2.06° and 6.9° over most of Skylon's flight in air-breathing mode, and is greatest at 25 km.

http://www.reacti...tput.xls

You will also find the rationale for the curved engines explained here:

http://web.archiv...faq.html

Your snarky comments are getting quite irritating so I won't be answering any more of your questions.
TheGhostofOtto1923
1.3 / 5 (14) Jul 22, 2013
You're guessing again soggy.

If you look in the following file you will see that the angle of incidence varies between 2.06° and 6.9° over most of Skylon's flight in air-breathing mode, and is greatest at 25 km.

http://www.reacti...tput.xls

Your snarky comments are getting quite irritating so I won't be answering any more of your questions.
So in other words you guessed somewhat correctly. Sort of. But not really.

Please thank me for prompting you to do the research ex post facto in order to actually learn something.
Estevan57
3.2 / 5 (22) Jul 22, 2013
Good guess, sogley. Looks like you are right. And with a direct source, good show old bean.
sogley
5 / 5 (5) Jul 24, 2013
Good guess, sogley. Looks like you are right. And with a direct source, good show old bean.

Thanks, Estevan.

No, it wasn't a guess. I remember reading the second of my links, http://web.archiv...faq.html , about 18 months ago on Reaction Engines' website. It's not on their website any more but I knew where I could find it. And I just happened to be looking at the first of my links, the Excel spreadsheet, for entirely different reasons a few days ago so it wasn't difficult to quote it.
Eikka
2 / 5 (4) Jul 24, 2013
in the same configuration but without the curved engines?


Tell me again, how exactly do you make a curved turbojet? A flexible shaft?

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