HOTOL - Spaceplane of the future

[@TheBigBowks]

My mother worked at UMIST in the 90s and had a half profile fluid dynamics model of the HOTOL hung on her office wall.

[@jasonjase8661]

Instead of a runway couldn't they either used a track (magnetic or otherwise) to increase the ship to a speed on the ground

[@donkoltz1]

@@jasonjase8661 Likely this was the most solvable of all the issues this design faced.

[@julopabene8736]

This is fascinating, and honestly gives me hope for Skylon, seeing how much work already went into making a project like it work. Great work on this video, a really good watch!

[@Brookspirit]

I remember HOTOL from when i was a kid, I'm still waiting for it.

[@kitesurferlee]

Me too I’m sure I read he went to America

[@ninjanicholas2459]

It could probably not work on earth but it could work on Mars.

[@robertgoff6479]

That and flying cars and hoverboards.

[@rboosterman9944]

kzbin.info/www/bejne/p3TFmKKngsicqKs

[@jocramkrispy305]

hopefully the engine's descendants protoype will be test fired this year or next

[@IanValentine147]

I remember it from when I had my first job at BAe, so exciting. This is the best description of the project I have ever seen. Thank you!

[@Charlie-UK]

My father worked as lead designer on the engines for Hotol at Rolls-Royce. Alan Bond is a hero. Work on the new generation of Reaction engines SSTO engine plods on. I hope I see it in my lifetime...

[@paulmakinson1965]

A few of the engineers that worked on Hotol (Alan Bond, Richard Varvill) went on to create Reaction Engines and the project to build the Skylon SSTO spaceplane. They are working with the European Space Agency and Lockheed Martin to develop the SABRE engine that uses the same ideas as Hotol. They have created a functional precooler that does not frost. Liquid nitrogen is used as the heat transportation fluid.

[@jocramkrispy305]

Lockheed Martin?

[@richardvernon317]

I once met somebody who worked on the Project and asked her why the project was cancelled. Her reply,We cocked the maths up and it wouldn't have worked.

[@thesauce1682]

make sense

[@jeanpaulchristian3282]

@@thesauce1682 no that is not the reason @Richard Vernon It was political- I can't remember his name but some dumbarse politician as all British politicians are cancelled and classified the project because they were concerned the technology will get into the hands of the Russians or Chinese who may successfully complete the concept before the UK PUTTING THE uk at a strategic advantage. And today what we have is a Yellow haired idiot as PM and people being sent through border check room at Heathrow mixing people from redlist countries from covid countries IN THE SAME ROOM- but the redlist travelers are the only ones required to hotel quarantine. And Ireland is trying to figure out how three cases of the Indian variant in in Ireland ( the border control room was full of Rich Indian families trying to escape before Indian passengers are banned from entry- giving time for all the rich Indians to get their families out and bring Indian variant into UK.

[@635574]

That was probably the lie they got told as it was cancelled

[@paulwestwood4417]

Reaction Engines is still pursuing a spaceplane and 2020 the project passed a concept phrase with the European Space Agency. It is true there were design flaws with the original Hotol and blocked by patents, but new solutions where found. This gave birth to Reaction Engines and the Skylon. But the name Skylon has seemingly been dropped from their website as they pursue a two stage concept. Reaction Engines are concentrating on The Sabre Engine, which has passed a number of milestones. Check out their website www.reactionengines.co.uk.

[@ronaldgarrison8478]

@@jeanpaulchristian3282 You have a problem with blondes?

[@BigCar2]

Great video explaining the life of HOTOL!

[@Th3_Gael]

Don't often see comments from yourself on other people's videos. Glad I saw it on a decent video like this

[@drawingboard82]

Dude this is fantastic. I remember Hotol as a kid and you've done a great job.

[@Eff-U-Kay]

Great narration. As a kid I was obsessed with this. Didn't understand any of the mechanics but nevertheless fascinated by it. I was in a book I owned as a child which sadly I lost. I think it was a kids encyclopedia.

[@Thumblegudget]

I had a similar fascination. Picture in a kids book, but no more information. Thanks for the compliment. If you’re still interested in the mechanics be sure to check out my video about the engine.

[@paulwestwood4417]

The Hotol project developed into the Skylon under Reaction Engines. But even this may have changed to a two stage launch system. The consistent component is the Sabre engine being developed by Reaction Engines. Hopefully, this will give you some key words to go on.

[@jimmarburger611]

I remember this project, and was excited at the time. Like other projects of this sort it was canceled due to lack of cargo capacity, engineering problems and lack of funding. Thank you for the content, I'd like to see this concept work and love reading about Skylon. Hopefully they can solve the problems associated with these concepts.

[@hempsellastro]

From someone who saw this story from the inside can I say another good job. What you have there is what we called the “Prince Charles brochure,” so guess who it was originally prepared for, but I am not sure if he ever saw it. It did not describe the engine properly because, as you said, it was a secret. However, the RB545 is described in "HOTOL's Secret Engines Revealed", Spaceflight, Vol 35 No 5, May 1993. And, yes; the undercarriage mass due to take off loads was the concern leading to the take-off trolly - that nobody ever thought was a good idea. It was brilliantly worked around by Alan Bond and Richard Varvill when they revamped HOTOL to become Skylon.

[@Thumblegudget]

Thanks Mark. I really appreciate the compliment!

[@RobSchofield]

I'd love to hear a follow-up to this, as your presentation style is superb.

[@Thumblegudget]

I actually have another one about HOTOL I’ve been tinkering with for a while. I’ll get it up sometime soon.

[@iancash3559]

Followed HOTOL since Tomorrow's World, fortunate to have since met two of the Three Rocketeers. Love the little Easter Egg at the very, very end! Subscribed...

[@newsteada]

Fascinating trip back. Like you I followed this very closely during the early eighties, I was actually an apprentice at RR in Derby at the time. I have a copy of this brochure which I picked up at a Farnborough Airshow around that time. One of the moments which I remember vividly was attending a lecture given by Bob Parkinson of BAC, who was the engineer in charge of the project and one of the things he said was that they had basicly solved the autonomous flight control issues using the EAP aircraft technology demonstrator that lead to the Typhoon fighter. As he put it, "we could fly the EAP with a Teddy bear in the pilot's seat!" Interestingly unmanned aircraft are the big news in combat aircraft now and BAe have been doing a lot of work on this that may be leading into their Tempest project.

[@Thumblegudget]

That’s pretty awesome that you still have the original brochure. I found my copy online and at least a couple of pages are missing.

[@andylaweda]

The trolley launch meant that the undercarriage didn't need hydraulic systems to retract the gear after take-off. The landing undercarriage dropped under gravity with no hydraulics to save weight.

[@LuciFeric137]

The abandonment of the X33 was a real shame. They had around 60% airframe completed.

[@JFrazer4303]

It was completely unworkable. Too many revolutionary new advanced technologies were required, and none of them produced a static bench-test article. The real shame is that they picked it instead of the McD "DC-Y" follow on. The Lock-Mart X-33 was graft, and not intended to make a useful vehicle.

[@stehpengray2084]

Fan task video. Much appreciated the time and effort that went in to it.

[@adodgygeeza]

Issue with the Skylon configuration is that in the rocket mode in a vacuum the exhaust spreads out and bakes the rear fuselage. NASA picked this up in about 2014 and wrote a paper on it. The engine needs to go back to the rear.

[@Thumblegudget]

I am aware of this one. Last I heard there wasn't particular concern on the part of the designers because the fuselage is designed to deal with reentry and the heating from plume impingement is far less severe than that.

[@adodgygeeza]

@@Thumblegudget if they aren't concerned it would appear odd that they are essentially currently planning to use the Skylon as a reusable first stage and not use the LOX mode of the engine at all. Essentially the rear fuselage would end up being an extended nozzle, if we look at the materials and temperatures they tend to use on a radiatively cooled nozzle (carbon carbon and niobium) it is somewhat higher than the tiles that they were planning on using plus they is the issue of the insulation on the other side of it.

[@jocramkrispy305]

@@adodgygeeza The first stage does use LOX. The TSTO concept actually has a worse reenty heating problem. The huge advantage of TSTO is it massively de-risks development as first stage mass over-runs aren't as important due to the rocket equation.

[@Peter_Morris]

Oh man thanks so much for this video. I’ve always been a huge space fan. I grew up in the 80s when it seemed like LEO was so close for everyone. I’m excited for the sequel, because I’ve been following the SABRE engine for a while now.

[@RobSchofield]

That was about the best overall picture (political and engineering) of HOTOL I've ever seen. Earns a sub from me. Superb.

[@tylerdruskoff9689]

THIS WAS A GREAT VIDEO!!! I CANT BELIEVE YOU BARELY HAVE 1K SUBS! THIS QUALITY OF WORK DESERVES AT LEAST A MILLION(probably a lot more). Best wishes. Hope your channel grows as I continue to watch this profesional, original, and high quality work.

[@francisdavis1271]

Those of us in aerospace were well aware of HOTOL as yet another project to provide affordable access to orbit. The company "Reaction Engines" with their "SABRE" engine is the current manifestation of the concept though the engineering details are different. At the end of 1950's the concept of Liquid Air Combustion Engine (LACE) was conceived and SABRE is the engineering demonstration of that concept. I believe there really isn't a vehicle anymore as most effort is focused on developing the engine tech... and so far seems promising.

[@wingnutzster]

As an aeronautical concept artist I can tell you that the creative decision to portray the take off out of a country airport is purely for the aesthetics of presentation, I imagine there was some direction from the client to avoid setting the take off in developed or built up areas. For the period the illustrations are quite technical and intricate but the engine is a difficult concept to relay to the average joe. Ideas like this have a life and a character and when they die it makes me sad.

[@rickrunner2219]

The best document of aerospace engines and crafts I've seen, thanks for the great job. Great job.

[@ggir9979]

Great video! I hope you are going to make a whole series about space planes, they are faschinating indeed! (Glad to see you tuned down the music, makes it easier to focus on the technical content) Cheers (subscribed earlier today!)

[@bmobert]

Thank you. I remember loads of hype about HOTOL but never heard any of the details.

[@redstoneablecz5742]

I'm proud to be in the first 1k subs, remember me on a million! Also keep up the good work, this video is awesome

[@asteronx]

If you are not already aware of this space plane, have a look at the Rockwell Star-Raker Space Plane for NASA. Like the HOTOL, it too was a forward thinking project at a time when 'scientists and engineers', primarily, wanted to venture into space.

[@richardike2342]

I have designed a combat Drone with the vertical stabilizer on the Nose like this Aircraft. Nice to see l am not alone in this.

[@swiftnicknevison4848]

Great video. Very interesting and well presented. Glad youtube recommend this to me. Been fascinated with HOTOL and skylon ever since i saw the documentary The three rocketeers years ago. I still follow reaction engines and check up what they're up to every month or so. Subbed.

[@timmurphy5541]

Wonderful, thank you. I remember reading about HOTOL on Hardy's Drawing Board in the magazine Look and Learn way back when...

[@rustyheckler8766]

I remember HOTOL from a popular science back in the early 90s, being a total aerospace geek I knew the design had its issues just upon sight of it, it was the engines that had caught my interests.

[@anonymous-rb2sr]

Wonderfully crafted video sir, on a subject nearly no one had ever heard off where information is scarce to find at that! Your video made me think of the future of space vehicles though: Let's say that a wide range of different technologies, those that are under active developement today, all reach maturity without any hurdle, all turn out to be physically possible etc, basically a setting where every conceptual technology has arrived to it's peak efficiency according to the rules and limitation that come from their design, ... What then would win the competition to become mankind's chief technology for bringing material to LEO? Would the market be split, would a specific type of launch vehicle be more efficient for a certain type of payload? All this to say that I feel like the economics will be more important than finding the best technology, to know what sort of launcher will make up the bulk of public and private launch fleets, we need to know where the demand will come from, and what shape it will take Simple example: a technology like HOTOL/SKYLON, I fear, would be very poorly adapted to bulk material heavy launches, and if this is the face of the demand of tomorow, and if conventional rockets can put the same weight to orbit as SKYLON but for cheaper, then I feel like it won't matter if or how well their technology works, that even if all the technical aspects are perfected to the ideal theoretical curves, that even then the SKYLON and other air breathing hybrid engine SSTOs will simply never be used, even if they work, because they cannot be scaled up the same way rockets can, and because at their current size, rockets can do the same job for cheaper What do you think of that? Will advanced and perfectly serviceable technologies like the ones used for SKYLON end up being scrapped simply for being suboptimal to the demand? If so, is it a waste to spend so much time and energy developping those technologies that no one will ever use?

[@johnassal5838]

The hypersonic heated changers of the Skylon concept have supposedly been validated in shock tunnel tests.

[@Cartoonman154]

Nice breakdown of HOTOL

[@sjmachrihanish]

Great video. The ending seems sadly predictable. I was reminded of the experiences of Frank Whittle and also the Miles m.52 team trying to secure Government support. I have long owned a 33cm model of the Antonov An 225 in Soviet markings carrying HOTOL on its back. The model of HOTOL must be a very early design because it has the fin at the back, a much larger one than when it was repositioned at the front. It does, however, look more aesthetic. Thanks for producing this informative video.

[@schrimblo]

this is criminally underrated

[@MsAnyOneANDavryone]

Nah man, there is a lot of physics that this guy is not taking into consideration. If it was that simple, do you not think it would have been done already?

[@hinzuzufugen7358]

Thank you. That thing was haunting my mind since about 2014.

[@Declan-pg8cg]

And Reaction Engines have done tremendous work on the Sabre engine. Unfortunately SSTO's presently have more cons than pros. It sometimes seems like we're going backwards in regards to space technology; the recent contenders for the current moon landing vehicles being a case in point. I'm not British, but I would love to see see Skylon spread her wings.

[@therealspeedwagon1451]

If skyhooks became widespread in space then I’d see sstos becoming more viable

[@johnmpowell]

Great video! The road not traveled. The HOTOL engineering is still out there and contributes to things to come.

[@johnassal5838]

HOTOL being an aircraft would've had the potential of in-air refueling. There's also some viable concepts for condensing O2 out of ambient air during horizontal flight, possibly allowing such a craft to take off without any liquid O2 which would make it considerably lighter and probably eliminate any need for that take off sled. The real achilles heel of any such system (including Skylon) is that it absolutely requires a high flight rate to bring costs down enough to use said capacity. There's just no middle ground over which you can count on the demand that would justify the number of flights that in turn lowers those launch costs enough to create that demand in the first pkace. Yes, this is a very circular catch-22 that's only resolvable by either _mandating_ the demand or letting other launch systems develop the market.

[@natehood6161]

Wow, thanks for such a well researched video.

[@RXTRUX1]

The most interesting question is why were the engines suddenly classified as they had started out fairly open as such things go.

[@trespire]

One word, hypersonic cruse missles.

[@eddiebleasdale3408]

Brilliant. More please.

[@alexeytsybyshev9459]

A question I have after this is: Since the Hydrogen would be used for precooling the incoming air, does that mean it would not cool the combustion chamber and nozzle? So, they would have to be ablative? Doesn't that defeat the purpose of reusability? Or were the nozzle and combustion chamber supposed to be easily interchangeable?

[@RogerM88]

While SpaceX is focus in Starship development, Blue Origins or ULA could look into investing in Reaction Engines helping with the development of their Skylon prototype. If successful. This concept has so much commercial potencial as in Aeronautic Industry as in Space exploration.

[@paulwilliams2663]

Was so excited about this early 80s

[@ChargedTTq]

From the moment the concept was described I knew this had to of been the genesis of Skylon. Unfortunately I feel that Skylons ambition to propel a manned space plane has made it bite off more than it could chew. Any cutting edge spaceplane tech would need to be vetted with many unmanned flights, and they also represent a better commercial opportunity.

[@jocramkrispy305]

Where do you get manned from? A manned pod could be carried as cargo, but it was designed as an unmanned vehicle.

[@davidgifford8112]

Spoke with Bond, Parkinson and Scott-Scott (the inventors of the concept) on several occasions. Making the engine secret (still is) was a massive impediment to continued development. However the biggest problem was being able to trim the vehicle as it’s centre of mass and centre of pressure changed radically within the flight profile. At time of cancellation the problem had not really been solved, a fresh start was needed. Getting around the Rolls Royce secrets problem resulted in Sabre, sticking them on the wings to calibrate the CM with CP solved the trim problem. To get the funding they needed to demonstrate that the Heat exchanger technology would work, once that was done, the US got interested as a propulsion system for Mack-5 hypersonic aircraft. Now the original design engineers have gone I don’t think Reaction Engines are interested in developing Skylon any more. Richard Varvill (Reaction Engines founder) estimated it would cost £50 billion to get to demonstrator flying.

[@jocramkrispy305]

It isn't still a secret, was declassified in the 90s.

[@ptonpc]

I remember when it was announced and the excitement at the time.

[@JFrazer4303]

We know of a few test models of hypersonic air-breathers, and a few non-flight tested airbreather/rocket hybrids. Good luck putting it all together into a system that is airplane-like reusable. It hasn't been done yet. So far, the best body shape for such a vehicle is the old Soviet Lozino/Lozhinski "Lapot" (wooden shoe) body of the Spiral. Used in the HL-20 and today in the SNC DreamChaser. NASA Langley said that it had "exceptionally benign thermal characteristics" and good handling from hypersonic down to landing speeds. They said that it might not even need carbon-carbon on the nose and leading edges. The flat up-turned nose of the Spiral/MiG-105 made a stand-off stagnant layer that kept high temperatures away from the nose. (Of course in America, it was too clunky and "Russian" looking and of course "if it looks right, it'll fly right" is most important) For some reason, this body shape wasn't used in the "MAKS" spaceplane 1.5 STO. We know why it wasn't used in the Buran Shuttle: Uniforms and suits dictating to engineers. Of course, then there's the Rockwell "Star Raker" HOTOL SSTO. ≈2500 ton take-off (jettisoned take-off wheels), 100 tons to orbit. It also had hypersonic air-breathers, but then turned them off and switched over to rockets. Due to "wet wings" (loaded lifting structure) it flew into orbit and had low heating (low loading) on landing.

[@gregorykotoch5045]

Love the 80's artwork in those magazines. Also, as for the original design with the engine at the rear, why couldn't they remove the heavy hydraulics from the rear and replace them with simpler electronic actuators like Electron or Astra does offsetting some of the rearward weight? At the same time by using the front to store the heavy batteries even more weight would be offset?

[@Mrequine1]

did it have a hybrid jet rocket engine??

[@LuciFeric137]

Very impressive work. Subbed.

[@jakkyte5733]

Very ' Fireball XL5 ' ! Hope it bares fruit ! Maybe CANZUK can get it together ?

[@maleavitohl5419]

very epic, thanks man!

[@ignorancebeater650]

4:16 Yes and no. While the payload of a modern launcher is usually bigger, that's mainly because they can also deliver multiple payloads. In actuality, however, satellites have become *smaller*: the average weight per satellite is actually around 3 tons these days. So, on itself, it could still be a viable way for economically sending satellites in space, compared to one-use-throw-away rockets.

[@chrisg5271]

Like most comments here I grew up keenly seeing the possible development of HOTOL and wanted to see it happen, loved this presentation. Watching Spacex achieving so much now and their iterative method of development, I wonder if this is the real key to success as previously we depended on such exotic materials etc., which HOTOL and Skylon likely would have needed, making it scary financially to approve for development ? Maybe we could take some of this iterative knowledge to succeed ?

[@simonhulmesh]

The HOTOL was the prelude design of the SKYLON as they didn't have the SABRE engine yet.

[@dandare6865]

It was a great looking machine, i hope

[@Psychonauta]

Hi, awesome material, where did You got that drawnings? And could i use them in my articles?

[@Thumblegudget]

I've put most of my sources in the video description. I don't own any of the images I've used, so no objection on my part.

[@Psychonauta]

@@Thumblegudget ok, understand, have nice day and keep up the good work

[@ignorancebeater650]

Anyway, very interesting vid. I remember the whole HOTOL thing from way back, but I never got around searching why it never came to be, so this was really interesting. Bit of a strange ending of the vid, though: long black pause with nothing, and then a small excerpt from the BBC, or something? Anyways, I'm a bit more familiar with Skylon, but I was wondering if you've made a vid about that as well?

[@hariprasad6871]

very interesting thank you

[@thomasciarlariello3228]

Did you ever see Mutsuro Bundo's Patent one could build of Robert L. Morrison's patented lighter than air solids "SEAgel" or "Biofoam" sealed in a metal foil to have additional layers of ceramics.

[@davidmarkwort9711]

This seems to be an almost copy of Eugen Sängers construction, he envisaged Shuttle Craft to a Spacestation in the 40's, he even designed a vehicle which looks very similar to this HOTOL.

[@markgouthro7375]

I want to hear more about the mission to destroy Mars!

[@CyberSQUID9000]

Forced to shutdown by UK government and passed to Lockheed Martin, working prototype rolls royce scramjets, new alloy skins the lot , but had design flaws around centre of mass and thrust changes

[@slifox2752]

As far as I'm aware, reaction engine, pretty much gave up on heat exchange jet engine hybrid... and now using the heat exchange part of the design for industrial cooling...

[@rorypenstock1763]

Have you heard of the MUSTARD spaceplane, and what do you think of the triamese concept?

[@Thumblegudget]

I have heard of it and it looks interesting. Might be worth a future video.

[@jocramkrispy305]

it's not *much* different from Delta IV Heavy and Falcon 9 Heavy ;)

[@minkshaming]

Hotol makes sense and will be built and used easily and on-time. In Kerbal Space Program.

[@kentonian]

it wont because anyone who plays KSP know SSTO are dumb

[@minkshaming]

@@kentonian Not in KSP, they logistically make alot of sense. ...in a version of Earth 1/10th of our size

[@TransamJc]

HOTOL is a predacessor for Skylon and reaction engines

[@francisdavis1271]

There's an annoying issue that hopefully isn't anymore but British systems were often rejected for monetary and political expediency for US equipment. Unfortunate in many cases. The US Air Force interest in the SABRE engine has both positives and negatives. I want to see the British engine employed.

[@martinbaldwin1906]

Britain always makes makes me smile. Such a small country but always big ambitions. I think reactive engines had and have plans to put people on Mars!

[@JosephDent-qd9ih]

Outstanding lifting. Dr Dent astrophysicist Rocketeledyne owner.

[@benetedmunds]

Another coulda-shoulda-woulda (like, in a sense, the TSR-2). Fingers crossed for Skylon. Does its "Sabre" engine still use hydrogen in its heat exchanger? This is something I hadn't realised. But this is a great video - a wealth of information. I too remember it on Tomorrow's World! Sheesh, I'm old!

[@jocramkrispy305]

No, SABRE still uses hydrogen as the heat sink, but uses helium as an intermediary.

[@thomasciarlariello3228]

Did you see Hector A. D'Auvergne's Patent?

[@alanjenkins1508]

HTOL was not a practical design because hanging the heavy engine on the back of the vehicle meant that it is not possible to maintain the centre of mass through the whole flight regime. It needs to carry a lot of heavy fuel and as it is used up the centre of mass moves back and the vehicle becomes unstable. That is why Skylon mounts its engines on the end of the wings.

[@Tim67620]

Hotol was flawed but fixable. The Government was not willing to fund it to completion. Alan Bond formed Reaction Engines because he knew what needed to be done to fix the problem and made Skylon very public to encourage funding. But he was very distrustful of Government support because of the way they abandoned Hotol. Progress was very slow because of this and it is amazing what they did with what they had. I was aware of Reaction Engines in about 2000 and have followed their progress since. They finally got the attention of ESA after they demonstrated their precooler success. They also received funds from the Government Science Department. However ESA had their own Spaceplane project and I didn't trust them at the time. They have now linked up with US companies and Skylon seems to have fallen further and further back. They are all after the engine (Sabre) and the whole program appears to be falling into the hands of the US. This is just another sad example of a brilliant concept that is developed in the UK but is lost to foreign lands because of cost.

[@gamergeek4000]

Looks like it was launching from south america according to the diagram on the how it operates page

[@jocramkrispy305]

That'll be Guiana, the ESA spaceport.

[@bryphillips]

our info on the progress of the super chiller are very out of date, as well of the fact you missed a startup thats about to start doing these same missions using same scheme

[@DigGil3]

I want a video explaining why Skylon is taking so long to develop.

[@raykewin3608]

Testing in Colorado.

[@arnavkalgutkar6169]

@Michael Sharp They are also getting a shitload of ESA money now, so don't worry!

[@florianhoppe4159]

Short Answer: Had to start from scratch, because of HOTOL patents. Plus having basically no serious funding until REL got into ESA's LAPCAT program about over a decade ago. After that they finally got far more interest and money from the Space and military Sector. (Lately also funding from Darpa, after they set up a devision in the US.) However, don't except Spaceplanes in the near future, since the current focus is more in the engine. (Which probatly will see some first use in some miltary tech.)

[@grahamcampbell8297]

They’re still working on SABRE engines and hope to have them flying in the next ten years.

[@Dave5843-d9m]

The super inter-cooler seems to be working and might have restarted the project. Not that anyone would admit it.

[@scicat6531]

video suggestion: ayaks waverider: not a spaceplane per se, but rather close to it- and using some really interesting technologies to do so

[@SimonAmazingClarke]

Is skylon using the Sabre engine? Unfortunately I see this going the same way as Betamax. A great idea and more efficient system but totally bypassed by technology.

[@HeWhoX]

Very interesting idea! Guess, Skylon Project shouldn’t be worse. Future of orbital flights belongs to shuttles anyway. At least, meaning manned missions.

[@JazzStoryForBullet]

super !!!

[@piotrd.4850]

HOTOL, Hermes, Skylon, Buran ... yeah.

[@take5th]

If hydrogen absorbs inlet air then its compression / pressure will increase. Weight penalty?

[@jocramkrispy305]

it doesn't, it's separated by a heat exchanger

[@3ddade]

Cool I always wondered what happened to it.

[@LORDwilliamsDJ]

back in the 90s you had big harding posters about this in London . then it disapeard

[@thomasciarlariello3228]

My dad's brother designed a spaceplane having an external ramjet.

[@Rbourk252]

The major obstruction to exploiting space is the contradiction between the nation state and the rapid development of the global means of production. In a world where the greatest investment is into the means of destruction, governments are at best very dubious about a rival constructive project like Hotol. For all the blabber about Britain ruling and being great, we became both protective and secretive and dependant on ‘other nations’ before doing anything mildly progressive. This video inadvertently exposes the modern day Brexit situation and the distorted reality of its proponents who will now never have alternative funding, lots of national official secrets to keep and laughably, no development partners to hide them from. It’s also an insight into the mind of old greying politicians with pinstriped suits and thick rimmed spectacles. Always conservative, predominantly conservative and what’s more very reluctant to be anything other than conservative.

[@sarcasmo57]

I hope Skylon has a happy ending

[@makex_se]

Seems like a bird strike at launch would be a VERY costly and dangerous event. Especially if the landing legs arent made to handle the weight of a fully fueled vehicle. Could this be another reason air breathing rockets just wont takeoff :p

[@Thumblegudget]

For sure there are downsides to the hydrogen filled precooler on HOTOL. Both HOTOL and Skylon were designed to be able abort the takeoff run though. Likewise both RB545 and Sabre were configured so that a bird couldn’t enter the engine and strike the precooler with significant kinetic energy.

[@silverbackakasherby2033]

Is that scram and ramjets being used at the different altitudes?

[@Thumblegudget]

It's a combined air breathing and rocket engine, though as I mention there is an auxiliary ramjet off the air intake.

[@michaelginever732]

Didn't the brains involved in this project go on to form Skylon. Their Sabre engine has achieved the required air precooling which I recall they were saying was a big hurdle. They probably don't have the money to make it actually happen. It would be wonderful to see it come to fruition, but I'll be surprised if it does.

[@timmurphy5541]

Well, their next step is demonstrating the engine cycle. They don't have the money to blow up 15 attempts which does make them slower but they're still there and did recently release videos of a test for the preburner system (sort of like the starter motor).

[@drhot69]

Calling Elon Musk, Britain has a concept plane for you.

[@timmurphy5541]

@@drhot69 he knows already and is unimpressed. I think the basic problem is that Skylon requires multiple leaps in technology and a lot of spending before one can launch anything. The 2sto designs are a lot less risky but also somewhat limited. He has found a way to take risks more progressively and get paid while doing it. I'm still a Sabre fan but I can see the situation.

[@oglordbrandon]

Had the space shuttle been canceled, we'd all be staring at it's overly optimistic brochures and pining away at what could have been.

[@Thumblegudget]

Well with the space shuttle we can look at the original fully reusable booster-orbiter concepts and use them as inspiration for the future, eg Starship. I personally think exactly the same can be said of HOTOL, and especially of its engines.

[@KetuParmar5]

Interesting