The Reaction Engines Skylon Master Thread (1)

[mr. mark]

The question really has to be is it financially worth it. There just isn't enough satellite business to make a strong business case. It would have to take over almost all of the large satellite market and it cannot launch US government satellites because of ITAR restrictions. It may never be built even if the technology proves out.

[DLR]

I guess if something like Skylon were availible even at $2000kg to LEO, it would take a big chunk of the satellite market, with an additional stage also to GSO. And with lower launch costs, greater demand would of course be generated. There would be many more organisations suddenly with the opportunity to put their own stuff into orbit.

[krytek]

I wouldn't be too sure that REL's success is dependant on Skylon.
The Sabre engine and the technology behind it probably has hundreds of other uses.

[john smith 19]

Any LV today should be capable of flying a full mission unmanned and do so 10 times before carrying people, with all the unanticipated problems corrected.

Well Atlas V is has done rather better than that and hasn't Delta IV just done its 12th successful mission?

Note that is good for an *expendable* but aircraft might well do 200-400 *flights* before design approval and each will do some after they come out of the factory.

Contrast that with the 5 flights of the STS before going "operational."

I guess if something like Skylon were availible even at $2000kg to LEO, it would take a big chunk of the satellite market, with an additional stage also to GSO. And with lower launch costs, greater demand would of course be generated. There would be many more organisations suddenly with the opportunity to put their own stuff into orbit.

I think you lost about an order of magnitude. That's about the level that Spacex with F9H are promising.
When you're buying a roller coaster rider (the nearest business model I can think of to the current space launch business) the outfit that maintains the capability sells you a *one* shot go at using it and if it fails you don't get a refund) people become *much* more cautious.

But if it does not pan out on an RLV you can a)vent the satellite propellants and bring it back b)Close the cargo bay doors and come back intact. c)Dump satellite and collect the insurance d) Retrieve satellite if it failed checkout and repair it on Earth.
And when you've run out of payloads you want to launch you can sell your Skylon on to someone else.

The question really has to be is it financially worth it. There just isn't enough satellite business to make a strong business case.

Without a reference that should be followed by "In my opinion." REL have maintained their business model indicates there are enough people out there who would want *reusuable* orbital capability they'd pay the kind of money this would cost. Either for themselves or to re-sell as a service. A *true* space trucking operations.

The *big* difference is that word "reusable". No one would want to blow that kind of money on a 1 shot ELV with a 50% average failure rate for a new design first launch.

That makes it an "asset" rather than a *cost* of doing whatever it is you *really* want to do with (IE get your satellite into orbit).

I doubt many 1st generation customers would actually *launch* 200 payloads

But you could launch 10 and sell it to someone else who might want a few more, or rent it out.

Because it's *your* hardware. Virgin have demonstrated there is a *demand* for this. Branson is a pragmatist. If he can get reusable *orbital* with acceptable running costs he'd do it in a heartbeat.

Naturally there would be a slight surcharge if you wanted to upgrade your VG ticket to *full* orbital. 

it cannot launch US government satellites because of ITAR restrictions.

"In my opinion."

 The business model is to *sell* Skylons to people who have the money. As others have pointed out the USG has *several* runways big enough to accommodate Skylon in the CONUS. They *could* even sell multiple Skylons so DoD and NASA would not have to share. As to what they would be used for that would be the customers business, not theirs.

The joker here is the notorious "coupled loads analysis" and how much detail has to be passed between customer and LV supplier.

 IIRC REL staff were *very* aware of this issue with STS and have aimed to limit the effort required as much as possible. Not rigidly bolting the payload into the cargo bay should help a lot but I'm not sure if you can eliminate the requirement entirely from an LV (although no one does with loads on aircraft so being HTOL should improve their chances somewhat). The only other data point I can give is the addition of a thin foam rubber layer between the SSME and its engine controller cut engine vibration to the controller from 20g to 3g, which suggests it's all about knowing where to put the damping to give maximum benefit.

It may never be built even if the technology proves out.

Well I'd say it's closer to getting built now than say the X30 or the Ejector ram rocket design that space-access LLC were touting (and who were alleged to have multiple $Bn backing)

I've sometimes thought that REL have been heroically brave in stating up front that if you want something the size and weight of an Airbus 380 it's going to need a development budget like an A380. That's completely at odds with the grudging do-it-on-a-shoestring funding of UK govt projects. It looks like they are finally getting some traction and I'm really hoping they do an update for the start of next month.

Skylon is projected to be reusable 200 times. While that is certainly a lot when compared to today's throw away rockets, it isn't when we compare it to high performance aircraft.

Well the *only* "high performance" aircraft in it's league is the Shuttle (In this game M3 is *not* high performance, that's engine warm up ) with the most number of flights on a single *vehicle* was what 60?

A new operating cycle power plant and vehicle with new materials and you're wondering where the "low" allowed number of flights is coming from? I'd say 200 flights is a pretty *bold* goal to aim at.

It's 199 more than *any* current LV with orbital capability (Neither Xcorp nor Virgin Galactic are orbital and Spacex has not *demonstrated* stage reusability).

Also, how are the projected costs of a single Skylon flight calculated?

You might like to search this thread as I think this has come up. Note there is likely to be a big difference between the costs involved and the prices charged.

[jded]

The business model is to *sell* Skylons to people who have the money. As others have pointed out the USG has *several* runways big enough to accommodate Skylon in the CONUS. They *could* even sell multiple Skylons so DoD and NASA would not have to share. As to what they would be used for that would be the customers business, not theirs.

Yes, this is the important part. RE might end up profitable if only they sold a pair of Skylons to every government that is not considered dangerous by the West and would like to have an independent rapid (on a few hours notice) launch capability without all the fuss of normal launch infrastructure. How many countries would it be, 10-20?

[john smith 19]

Yes, this is the important part. RE might end up profitable if only they sold a pair of Skylons to every government that is not considered dangerous by the West and would like to have an independent rapid (on a few hours notice) launch capability without all the fuss of normal launch infrastructure. How many countries would it be, 10-20?

It's quite a few. If it can get clearance for sub orbital flights carrying people between normal airports (probably on LH2 only) this opens up market to whoever wants very fast long distance travel.

And of course there are the multi-billonaires who would quite like a new toy now they have grown bored with the $40m yacht. The Saudi royal family might like one or two as well.

Not dropping bits over the territory you pass over and reusability changes the game quite a lot.

[93143]

Any LV today should be capable of flying a full mission unmanned and do so 10 times before carrying people, with all the unanticipated problems corrected.

Skylon's test program sees it flying a few hundred times before it so much as enters commercial service.  Passengers come later.

[flymetothemoon]

Skylon is projected to be reusable 200 times. While that is certainly a lot when compared to today's throw away rockets, it isn't when we compare it to high performance aircraft. Nobody would buy a 747 if it could only fly 200 times before it has to be retired. What are the reasons for this short service life? Is it just a conservative estimate or are there certain limitiations inherent to the design?

Also, how are the projected costs of a single Skylon flight calculated?

I forget where exactly, but I remember somebody (Mr Hempsell I believe) suggesting that the 200 sortie lifetime was a conservative estimate which they hoped they would be able to prove could be greatly exceeded during the flight test programme.

[john smith 19]

It does not look like there is going to be an update this month either.

It's a big ask but if anyone does find themselves in and around Farmborough this year if they were to find themselves in an REL presentation could they perhaps set their phone on record and post a report of some kind?

I'm *hoping* for a co-ordinated update of the web site with any announcement of results on the day, which would be a reasonable use of their limited (at present) resources give them wider exposure etc.

But it would be nice if there was a plan B. The Register *might* report it but it probably won't even make the UK national news.

[flymetothemoon]

It does not look like there is going to be an update this month either.

It's a big ask but if anyone does find themselves in and around Farmborough this year if they were to find themselves in an REL presentation could they perhaps set their phone on record and post a report of some kind?

I'm *hoping* for a co-ordinated update of the web site with any announcement of results on the day, which would be a reasonable use of their limited (at present) resources give them wider exposure etc.

But it would be nice if there was a plan B. The Register *might* report it but it probably won't even make the UK national news.

You're right. Looks like they have decided not to steal the show from Farnborough now. Still that's less than a couple of weeks away.

I dunno. The BBC made a big fuss about the phase 1 tests. I am sure the Register will cover it.

In the meantime this might keep you going:

http://thespaceshow.wordpress.com/2012/07/03/mark-hempsell-monday-7-2-12/

[Crispy]

In that space show episode, Mark says that the website is "being upgraded this week" - whether or not that means new info, I don't know.

[john smith 19]

You're right. Looks like they have decided not to steal the show from Farnborough now. Still that's less than a couple of weeks away.

I dunno. The BBC made a big fuss about the phase 1 tests. I am sure the Register will cover it.

In the meantime this might keep you going:

http://thespaceshow.wordpress.com/2012/07/03/mark-hempsell-monday-7-2-12/

Much appreciated. Thank you.

[Moe Grills]

  Guinness Book of World Records indicates that a 200 second, Mach-6
powered testflight of a"scram jet" has been achieved by the American
agency DARPA. The Australians are also pursuing scramjet technology.
Mach 25 seems the goal.

So what advantages does Skylon's propulsion system have over scramjet
technology, if any?

[93143]

Ground start capability (=ground test capability), much higher T/W, lower aeroheating over the trajectory due to earlier transition to rocket mode, easier/simpler intake/nacelle/nozzle design and airframe design, don't need to carry separate rocket engines.

Not sure how Isp stacks up, since the publicly-available data is from the SABRE 3, which is an obsolete design.

[flymetothemoon]

  Guinness Book of World Records indicates that a 200 second, Mach-6
powered testflight of a"scram jet" has been achieved by the American
agency DARPA. The Australians are also pursuing scramjet technology.
Mach 25 seems the goal.

So what advantages does Skylon's propulsion system have over scramjet
technology, if any?

Even if working scramjets existed today, they are for air-breathing and only start working above Mach 5. Skylon is "simply" a rocket above Mach 5, shutting its air intakes and leaving any remaining air (and therefore heating issues) behind very quickly. Scramjets are also likely to be very heavy, so unusable for this concept. It is therefore difficult to marry the two halves of your question, short of describing them both separately.

I definitely couldn't do it more justice than Mark Hempsell does in the new radio interview with him, just posted above.

[hkultala]

  Guinness Book of World Records indicates that a 200 second, Mach-6
powered testflight of a"scram jet" has been achieved by the American
agency DARPA. The Australians are also pursuing scramjet technology.
Mach 25 seems the goal.

So what advantages does Skylon's propulsion system have over scramjet
technology, if any?

SABRE works from speed 0, does not need any other engines for low speeds
Scramjet need either rocket or jet+ramjet to accelerate to speed where it can start.

SABRE works outside atmosphere, does not need any other engines for final phases of the flight.
Scramjet cannot inject craft to orbital trajectory, rocket burn is needed after the scramjet.

So scramjet-engined vehicle needs either
1) 3-4 sets of main engines.
2) 2-3 sets of main engines, and carries oxygen for the beginning phase of the flight.

Skylon only need SABRE's

[tnphysics]

Well, a scramjet can share its nozzle and intake with the a SABRE engine. Performance gain (higher Isp from Mach 6-Mach 15) is the idea.

[flymetothemoon]

Well, a scramjet can share its nozzle and intake with the a SABRE engine. Performance gain (higher Isp from Mach 6-Mach 15) is the idea.

It's always seemed to me that on the way up, air is a major heating problem. Surely once you have gained maximum advantage from the air, you want to get out of it as soon as you can. Surely that optimises aeroshell materials, weight, costs and re-usability?

Unless you are talking about the Sabre engine technology being used for different applications. If you want to stay in the air it is a different proposition. Missiles?

Did they even propose aeroshell materials for the LAPCAT A2 study? Or is that one of the reasons they were suggesting such a vehicle is still '25 years' away?

[john smith 19]

Not sure how Isp stacks up, since the publicly-available data is from the SABRE 3, which is an obsolete design.

Mark Hempsell stated vacuum Isp is 4500 Ns/Kg. He converted that to 458sec (Vac)

Presumably this is the current SABRE iteration. Heat exchanger on stand at Farmborough, with key elements discretely veiled.

I'm going offline for a while. I heard the Space Show recording and some interesting other points were made.

The target 2 day turnaround is dominated by aeroshell inspection. A lot of work was done on this for Shuttle inspection post disaster and during the early 90s by Carnegie Mellon for robotic inspection. No idea how much of this REL are aware of. The data flows from the various possible sensors to do this should be within the scope of large conventional processor arrays. Faster turnaround -> more inspection bays (multiple customers) and/or more blades in the server.

Skylon can stay 2 days on orbit. A tourist class stay would be that long. A luxury class EG longer term where the body adapts is expected to need enough space to lay flat. This is anticipated to be chargeable at 6x the cost of a tourist seat at an orbital facility. With an anticipated $1Bn purchase cost and $1bn servicing (24 passengers per flight, 200 flights) you can work out the costs per seat.

Before anyone mentions "But Virgin Galctic are offering $200k a seat) this is for an *orbital* flight. IIRC the *only* people offering such are the Russians at c$20m (Unlikely to be the price paid but how much do you think you can get knocked off?)
VG is M3 then zero g for c15 mins, *not* a 2 day minimum with a KE 60x that of sub orbital.

REL are happy to accept funding from anywhere but have been warned that US investors could face *jail* as by funding space efforts outside the US you are funding *arms* under ITAR, as space == arms (in the US. not elsewhere).

I've sometime felt at least one session of Space Access should be held in the parking lot of the nearest strip club, just to remind attendees how  the US government seems to view attempts at non governmental launch efforts by anyone not tightly linked to NASA or the DoD

[93143]

Not sure how Isp stacks up, since the publicly-available data is from the SABRE 3, which is an obsolete design.

Mark Hempsell stated vacuum Isp is 4500 Ns/Kg. He converted that to 458sec (Vac)

459.  Not new information.  But the context was vs. scramjets; I thought it would be obvious that I was talking about the airbreathing portion of the flight...

The latest data I've seen is a graph from Varvill and Bond (2003), which shows an Isp curve only marginally better than that of a scramjet, three Mach numbers lower.  Peak looks like it's around 3200 seconds at Mach 2.  That graph is probably not from the SABRE 4...

Well, a scramjet can share its nozzle and intake with the a SABRE engine. Performance gain (higher Isp from Mach 6-Mach 15) is the idea.

A scramjet most likely cannot share its nozzle or intake with SABRE.  The main SABRE nozzles are the rocket nozzles; you can't run a scramjet through them.  There is an annular ramjet, but redesigning the intake and nacelle to be operable in scramjet mode would be a massive change in more ways than one.  It would be incredibly complicated, and heavy.  For one thing, scramjets with a significant Mach number range need fairly flexible variable geometry, even if they don't need to also operate in ramjet mode like this one would, so they tend to need rectangular flowpaths.  The simple jackscrew-driven two-shock or three-shock inlet or whatever it is SABRE uses is just not going to cut the mustard.

Besides, scramjets at high speed have a fairly narrow thrust margin.  You have to be very careful to optimize the geometry to maintain positive thrust.  Trying to jam a scramjet into a SABRE nacelle is likely to be suboptimal, which means it's not clear it would even work.

That's not even getting into the changes you'd need to make to the airframe to fly that fast...