HOTOL kit resources
The HOTOL is my most ambitious project yet. I tackled it for the challenge, and simply because I liked the looks of the HOTOL. It's not as through I'm a huge fan of the design, though as airbreather SSTO's go it's probably the best design yet. But I modeled it chiefly because I like the look of it. For that reason, I have no plans to model the (plug-ugly) Interim HOTOL, nor the Skylon, which is not so ugly but which is just too big a project at this time. It's beem a good 4 years since I started working, off and on, on the HOTOL model. It's been a long, long road; I'm in no hurry to repeat the journey.
Due to the weight of the model, the gear had to be strong! Resin simply wasn't up to the task; I didn't want to start casting pewter, or some other jeweler's casting technique. Instead, I cast a resin landing gear with a steel wire for stiffness. It works well; it holds up the prototype, which is heavier than the (hollow-cored, microballoon-filled) final model.
The HOTOL was a mid-1980's proposal for an airbreathing single-stage launcher. It was unmanned, and to save on gear weight that would otherwise be prohibitive, it launched from a trolley. Key to the design was the hydrogen-burning RB-545 engine. Unlike the contemporary U.S. X-30 project, which obsessed on trying to breathe air throughout the flight, and obsessed on finding an optimal scramjet design, the RB-545, by contrast, is an inefficient airbreather. But it doesn't need to be efficient, as it's mostly a pure-rocket which, up to Mach 5, uses the incoming airstream to turn the rocket into more of a ramjet. The marvel, then, is not how well the elephant dances, but that it dances at all; the RB-545's efficiency as an airbreather is less important than that it retain the advantages of a rocket (simplicity, high thrust/weight) with an initial flight segment of vastly improved fuel consumption.
The completed model:
Trust me, it's big!
Through the use of switchable "gear plugs", the model can be switched between:
Gear Up:
Gear Down:
And, of course, you can open
the payload door. Hey, it's an Anderson Model!
Some images of HOTOL:
This is a VERY early design of the HOTOL, but it shows
off the launch trolley nicely.
I currently have no plans to model the trolley, partly
because it's a very hard subject, and partly because this is the only picture
reference I have, and I have every confidence that it's very out of date
and not appropriate for the modeled configuration.
The HOTOL in high-speed flight. The Encyclopedia Astronautica has the same picture in color, though smaller.
This may be the final design iteration, but I didn't
have the heart to take the canards off. You may, if you wish.
I love this cutaway view!
Links:The Encyclopedia Astronautica has a nice little page on HOTOL
A brief version of the HOTOL story
Another HOTOL mini-pageThe HOTOL's design philosophy lives on in the Skylon project
Ninfinger's Quick Look review of the kit (Sven "Ninfinger" Knudson is an independent reviewer).
