It's interesting to think that being able to have a name is one aspect of re-usability. Why name something that is destroyed the first time you use it?How powerful names like "Enterprise" or "Ark Royal" or "Illustrious" are! It will be sad if Skylons only get numbers. I hope they get named and that the names live again and again like ship names do.
Good, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..
Given that Skylon doesn't have to be assembled at the site or transported there by machines, is that certain? At the very least doesn't one need a lot less people and/or equipment? Presumably it also needs quite a lot less liquid oxygen storage than a conventional launcher might.On the other hand, if there is a high flight rate (in surges perhaps) then one might need much more propellant storage than a conventional launch site..
they plan a 200 flights test programme.
Quote from: francesco nicoli on 12/04/2015 03:56 pmGood, I'm glad we agree to disagree. Now it would be very kind of you if you could let us continuing our "nonsense conjectures" without further poisoning the discussion..No, I will continue to point out the nonsense
Quote from: francesco nicoli on 12/04/2015 01:46 pmthey plan a 200 flights test programme.~400, not 200. Two vehicles, two years. One vehicle doing envelope exploration and about 30 abort tests, the other doing 204 orbital launches to demonstrate the specified service lifetime (200 flights, plus the 4 test flights each unit undergoes before delivery).I believe this was subsequent to the maybe-not-orbital boilerplate vehicle tests.There may be newer information, but I don't recall seeing it.
Quote from: lkm on 12/04/2015 03:51 pmDid I say they had built one? I said they had designed an engine cycle and built a heat exchanger which they indisputably have done and which multiple institutions such as ESA, AFRL, DSTL, UKSA, BAE and DLR seem to recognize as an achievement worth noting and/or funding, you may not consider it an achievement warranting praise but clearly these things have been achieved by the company and praise is not a necessary condition of achievement.There are many designs that have never left the factory or even drawing stage. There aren't "off the drawing board" ceremonies, there are rollout ceremonies.
Did I say they had built one? I said they had designed an engine cycle and built a heat exchanger which they indisputably have done and which multiple institutions such as ESA, AFRL, DSTL, UKSA, BAE and DLR seem to recognize as an achievement worth noting and/or funding, you may not consider it an achievement warranting praise but clearly these things have been achieved by the company and praise is not a necessary condition of achievement.
One of the phrases used in connection with Skylon that raises eyebrows is ‘aircraft-like operations’. Optimists picture a Skylon landing - much like a passenger jet - someone kicking the tires, filling up the tanks, loading a new payload, and then sending it back into orbit. And of course cashing the check. For this to happen REL will have to accomplish a second breakthrough in space technology in addition to air breathing propulsion: a never-before-seen ultra low maintenance spacecraft (and all associated systems: RCS, OMS, TPS, landing gear/braking, aerosurfaces/actuators, etc.)REL clearly expect to achieve this, hence the 200 flight test plan. But it’s not been done before. You can flip the reusability argument on its head and call expendable vehicles ‘maintenance free’. Sitting here in 2015 we don’t know what infrastructure will be needed to keep Skylon flying. But we do know it’s more than throwaway rockets need :-)The maintenance of a passenger jet is low because much of the time it’s earning money it’s at cruise. And that’s a very benign environment - not that much different to being in the hangar. But this will not be the case for Skylon: ironically it will not be aircraft-like.During the test flights REL will learn which systems need to be maintained with what frequency. If they get it all right first try, then the aircraft infrastructure analogy holds. Minimal inspection and maintenance will be done at the launch site (so it will require less pad infrastructure than STS.) And Skylon is only moved back to the assembly facility for major overhauls.But realistically, we can’t expect them to get it all right first try - some system will have teething trouble and need to be inspected/tweaked/swapped out. And now the launch facility begins to look more and more like the factory.Can we predict if Skylon will be gas-and-go for 200 flights, or need to be rebuilt every flight? Nope, not yet.
Quote from: Robotbeat on 12/04/2015 02:55 amOr no one will buy a Skylon because they'll be taking a huge risk.Reaction Engines and their partners will necessarily HAVE to operate Skylon for quite a while before they'll sell any.Of course: they plan a 200 flights test programme. MORE than practically any other orbital launch vehicle to date, afaik.
Or no one will buy a Skylon because they'll be taking a huge risk.Reaction Engines and their partners will necessarily HAVE to operate Skylon for quite a while before they'll sell any.
They very likely will be on the same scale. Hangars, propellant storage, payload processing facilities would be the same.
So look at Spacex pad but without the erector.
I mean selling launches /before/ all orbital launches have been completed.Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
And yes, I do think that such expensive vehicles will be a hard sell, especially with the significant ground support equipment that will be necessary.
There will be a lot of pressure by investors to get earlier income. That's why I think that if Skylon ever happens, Reaction Engines will be initially operating Skylon for customer launches (during the "test program," if you like). And at that point, it'd be really tempting to just continue operating, since they'll already have the infrastructure in place.
And of course, customers of Skylon would know this. That's part of why I am skeptical of the "just sell Skylons to people, and ignore the actual launch market." If Skylon ever happens, I really doubt that's how it will work.
Quote from: Robotbeat on 12/05/2015 01:28 amI mean selling launches /before/ all orbital launches have been completed.Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.IE for a piloted, 2 stage passenger carrying vehicle programme where there is only 1 test vehicle in the programme....
And I see you ignored the "and other reusable test-bed vehicles."
The fact is that Skylon cryogens propellants, unpiloted mode,3 miles long take-off run and very high takeoff speed - all forbbide access to any airport. The FAA will never certify Skylon for LAX, JFK or Roissy CDG or Heathyrow. Just sayin'
Just 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.
Just so we're clear, it was never the intent to operate Skylon from an existing airport. Emergencies are potentially a different matter, and if you really don't want liquid hydrogen on site, or you don't want the engines lit for the takeoff, you could always tow it. But the usual mode of operation would be from a dedicated spaceport.
Quote from: Robotbeat on 12/05/2015 01:28 amJust 2 years of flight testing for 400 flights is VERY optimistic, as we can see from SpaceShipTwo and other reusable test-bed vehicles.If I'm not mistaken, this would be after the boilerplate prototype testing to ensure the system works. It would be in large part a certification test series similar to what an airliner would go through.(Also, it wasn't strictly two years - just less than three.)