HOTOL - Anatomy of a spaceplane engine

HOTOL was a 1980s British project to build a totally reusable Space Shuttle. The project was cancelled and as it existed in the pre-internet age it's hard to find information about it.

In this video, with the aid of an original patent, I go back to basics to explain how HOTOL's unique rocket engine would have worked.

The patent referred to in the video is available here:

My original HOTOL video is here:

For an explanation of why I think SSTO spaceplanes are the future of space travel check out my original spaceplanes video:

The background rolling Earth orbit video is from:
"ORBIT - A Journey Around Earth in Real Time"

[jobob]

Rich, another outstanding video. I'll pass this on to my colleague, Adam Dissel (he's the president of Reaction Engines, Inc.). We've been teaching together at the AIAA short course on high speed air breathing propulsion. (I do the Air Turbo Rocket part, Adam presents the current Reaction Engines cycle and how it works, along with several other outstanding instructors in aerospace).
I was especially gratified by your explanation of how the concept of "SSTO" got so stigmatized; that squares pretty much right on with my experience, when I was a young engineer working on NASP propulsion systems. I no longer use the term "SSTO" because its so burdened with misapprehensions.
Instead, we use the term "high delta V missions". But you know what we mean.
Keep up the great work!

[KerbalAddict]

Thanks, I’ve been looking for a video on how the kerbal rapier engine would work, and this video did that perfectly.

[AR_]

Thank you! This is one of the best aerospace videos I‘ve ever seen (and I‘ve seen a lot)! I hope this video and your channel gets the recognition it deserves.

[LivakProductions]

The quality of this video is incredible, chapeau! Love the technical detail but simplicity.

[Platin_]

You broke down a lot of complex concepts very well, fantastic job!

[Impracticalwizardry]

As somebody whose rocketry experience is limited to sucking at KSP, I found this bloody riveting. Thanks.

[drawingboard]

You are really good. For sure the best videos on hotol.

[rorypenstock]

Very interesting. Now I'm interested to know how Skylon's engines differ.

[benetedmunds]

Super-informative. I was a bit distracted by my brain shouting "Eureka!" repeatedly.

[proph]

Brilliant video! despite always having an interest in rocketry, especially these last few years, I've always been slightly confused on the specifics of a rocket engine's function, but your explanation has finally cleared up a few gaps! It's also nice to see some more HOTOL love.

[glike]

The presentation, narration, and technology is superb! Thank you!

[zounds]

Excellent explanation of the HOTOL engine, working your way up from first principles.

[adambarker]

One of the best videos on YouTube! Please keep up the good work.

[RobSchofield]

Excellent! Yet another quality video, and about one of my favourite aerospaceframes. Keep it up!

[daveherbert]

Brilliant, brilliant, brilliant. Great explanation, so clear. I love the idea of disappointing SpaceX fans.

I'd like to see a single stage space plane exist. I hope that reaction engines succeeds in bringing this to fruition, though I have heard that they are getting funding from the military to build yet another missile.

Keep up the good work.

PS I wonder if Scott Manley has any thoughts on this, let alone the everyday astronaut

[jocramkrispy]

My goodness. Why on Earth did the algorithm take so long to show me this?

[РайанКупер-эо]

Aerospike engine is uniquely suited for expander cycle. And it is simpler then double bell or expansion/deflection nozzle

[JulianDanzerHAL]

4:50
that helps to a limited degree, pure rocket engiens and scramjets tend to have better thrust to weight ratios than jet engines or airbreathing rockets
and any vehicle gets lighter as it uses up fuel so the mass is dominated by whatever you use first either way
so either method ends up with surprisingly similar engine masses

[patreekotime]

Thats interesting. One thing you didnt mention is that by using hydrogen as a coolant for the hypersonic airflow, it is also pre-warming the hydrogen before it even gets to the pre-burner. Brilliant.

[DeltaR]

So underrated. I’ve thought about this idea before, however I had no idea that already existed. A question though, had they ever thought about reheating that excess hydrogen, and adding a variable nozzle to it?