I am well aware of how long the concept has been pushed - it makes me realise how long I've been in this game. I know Alan Bond well (in fact I work for him), and I know his co-designer on the previous concept HOTOL well too (Dr Bob Parkinson). I also know, that when they have to battle against entrenched, sclerotic viewpoints of people such as your good self, it can take a long time for development to come to fruition.

And by that, you demonstrate how little you understand of the subject in question, sorry. Your argument is itself meaningless. The various technologies are developed to considerably more than merely component level, and I would hope you are not stupid enough to think otherwise, but are trying to illicit a response. The key is take the various technologies to higher Technology Readiness Levels. Go look up what that means if you are not sure.

Again, that just belies your ignorance of both the process, and in this particular case, the hardware developed. You may benefit from reading the details on their website, as opposed to simply using it as an opportunity to indulge in your love of bashing - that way, you might (a) learn something, and (b) understand why the project is broken down into the distinct areas it is. Yes, I admit I am a physicist who works in engineering, as opposed to an engineer who works in engineering, if that is something you wish to use against me too.

Actually, your comments are most certainly not factual, because if you had read the information first, and had understood anything of what is written on the project, you would understand how lacking in clues you are.

If by rocket fanboys and ignorance, you mean degrees in physics, many years of experience of working on developing rocket propulsion, genuine contributions to numerous peer reviewed rocket propulsion papers, and well used copies of rocket propulsion books such as Sutton, Huzel and Huang, and Humble and Larson which are battered because I've had cause to use them out at test sites doing real rocket propulsion testing, then I suppose I am guilty.

So come on Mr Lyons, what is your technical background? I'm sure since you are so able to cast aspersions on so many rocket concepts, that you must have an exemplary background yourself.

Do you have evidence of your assertion regarding funding?

As for the "nothing to show for it but ever spiffier computer graphics", what about the currently built heat exchanger module, the tested heat exchanger, the tested rocket engines, the tested modified jet engine being used to test the precooler, the experimental turbine, the wind tunnel to test frost formation with the hydrogen in the heat exchanger, and a host of other hardware that has been built to test various aspects of the system? Hardly just computer graphics are they?

Note, this time, I must declare an interest here. I work for Reaction Engines on the ED nozzled rocket engine test programme, so I do know what hardware exists, and in fact the reason I am late replying to this thread is due to being at static test firings this week.

Mr Lyons, do you ever check your facts before your usual negative comments on various rocketry ventures around the world?

I'm sorry for any offence caused. I am just very enthusiastic about the cause!

I can understand where you are coming from completely. The task is certainly not easy, but we do believe it is achievable, and as has happened until now at Reaction Engines, the key is incremental steps towards the eventual capability.

Rocket engines do take a while to develop yes, but a deeply cooled air breathing rocket engine is in some regards less of a big deal than designs where they use a jet engine, a ramjet, a scramjet and a rocket to get into orbit. Yes, there are some elements of it that are fairly complex, but other elements of it that are more straightforward too.

Although the website lists the main projects, there are a lot of intermediate sub projects along the way that have been achieved or are in process at the moment, and as these come together, the more of that capability will be realised. We will do this, because we genuinely believe it is achieveable, we are too stubborn not to, and we owe it to those on HOTOL, Black Arrow and Blue Streak who blazed the trail. Besides which, I'll be out of a job if there isn't something shiny flying in a while ;-)

Yes, you'll be pleased to know, I know what the pintle is, I have had to extract it from the motor several times :-) Not straight after testing you'll understand :-)

Compared to a bell nozzle, yes, since it is operating at optimum efficiency throughout the thrust regime.

Absolutely, you're spot on :-) And in fact, the ED nozzle does have a very large area ratio. Even with the large area ratio, the performance gains compared to a bell nozzle should be greater than any mass hits you take by having a large area ratio nozzle in the ED. In terms of how great, that's what the ED rocket test programme that Reaction Engines is carrying out is designed to find out.

1) The graphics were produced a fair while ago. I daresay they could be improved nowadays. Much of the design work is in Solid Works, so I imagine that could be skinned and modeled accordingly.

2) Reaction Engines is focused on trying to develop an SSTO spaceplane, not a Hollywood movie. If the money was available, yes, I'm sure the graphics could be souped up, but when the budget choice is graphics or components for a rocket engine say, guess what wins in a rocket related company that is focused on developing the hardware?

Personally, I would rather trust a company that bring real hardware that has been tested to the table than a company that just has a bunch of gorgeous CG images and PowerPoint slides.

Actually not. Venturestar was a pure rocket SSTO, as opposed to an air breathing rocket SSTO. Big difference. Because it was reliant solely on pure rocket propulsion, the structural mass required materials that were very light, and one of the reasons it wasn't continued was problems with the composite non cylindrical liquid hydrogen tank, which was a major show stopper.

Skylon gains significantly by being able to use an engine that air breaths to Mach 5.5 before transitioning to pure rocket propulsion.

My pleasure. I'm sat here working on calculations connected with the ED nozzle this afternoon (the rocket side of the engine is the part I am lucky enough to work on), and thought it made sense to reply to some of the comments where I could.

As you can imagine, there is a lot more going on behind the scenes than is indicated on the website. The problem is, we are rocket people, not PR people, so getting the word out doesn't come naturally, and we spend the vast majority of our time working on the technical aspects :-)

That's why we are developing the ED nozzle :-)

The ED nozzle is a very efficient nozzle design and provides altitude compensation across the thrust operation range. Part of the engine development at the moment is concerned with development of the ED nozzle for this purpose.

Your understanding is spot on.

Then you may need to work on your reading :-)

The precooler tests were run separate to the thrust tests. The thrust tests were related to the ED nozzle work.

As for the reliability, well when I wrote the test plan for the ED nozzle test engine, I can assure you, that reliability was very much part of the plan.

As for you not seeing any prototype being tested, note the photograph of a rocket shaped object with hot flame coming out of it in the News section?

I'm sorry the photograph isn't any better, but none of us were prepared to step outside the bunker during the hot firings. I'm working on improving the photos taken during test runs.