
Chrysler's Radical Space Shuttle Design - rbanffy
https://www.thedrive.com/news/33905/chryslers-radical-space-shuttle-design-was-50-years-ahead-of-its-time
======
apendleton
> The aerospike engine isn't actually a new thing. Rocketdyne had been
> experimenting with them since the 1960s, and they're much more efficient
> than conventional rocket engines.

... kind of. Like they say, conventional bell-nozzle engines are optimized for
a particular altitude, while aerospikes are not, and it's true that if you're
going to use the same engine across a wide range of altitudes, aerospikes will
be more efficient on average across that wide range than conventional engines
will. At any particular altitude, though, a conventional engine optimized for
that altitude will be more efficient than an aerospike -- they're "jack of all
trades, master of none" engines. And it turns out, with contemporary multi-
stage rockets, we can and do use different engine bells at different
altitudes, which negates a lot of aerospikes' prospective benefits. Were
single-stage-to-orbit vehicles ever to be a thing, aerospikes might have their
moment, but it turns out SSTO configurations just aren't very good at lifting
much mass to orbit, so that seems unlikely.

~~~
rbanffy
SSTOs have the advantage of enormously simplified operation - no staging, no
vehicle assembly building, no stage mating, just land, fix whatever is broken,
refuel and launch. If the payload fraction is smaller than that of a
multistage rocket, it can compensate with cheaper logistics on the ground and
less time between launches.

~~~
pfdietz
Making those things easier is a lot simpler than making SSTO work.

~~~
rbanffy
We thought that reusing the shuttle would be easy and that relanding boosters
would be impossible and, yet, we were wrong both times.

Some things are impossible until they aren't.

~~~
erispoe
No these are fundamentally different. SSTOs make things expensive because the
rocket equation is unforgiving: every kilogram you haul into orbit needs fuel
and propellant, which in turn makes the rocket bigger and heavier, which in
turns requires more fuel and propellant, which in turns... So, you don't want
to bring up anything unnecessary, like taking your first stage into orbit SSTO
style.

Landing boosters is an incredible engineering feat. The rocket equation is
just derived from the laws of physics, it's not something you can change with
great engineering.

~~~
evgen
If the rocket equation is such an unforgiving bitch then why are you only
using two stages to get to orbit? By your own logic you should be using four
or five or even ten stages to get to orbit because otherwise you are hauling
up too much unnecessary mass on each flight. What makes two such a magic
number in this case? Is it perhaps possible that there are in fact real-world
tradeoffs between efficiencies in the rocket equation and engineering
parameters and that sometimes advances in technique or materials shifts the
optimum point?

~~~
erispoe
The more stages, the less favorable your ratio fuel+propellant / dry mass.
When you add stages, you add engines, tanks, systems... that you then have to
haul up to the next stage, making your lower stages heavier. Rocket equation
again.

Sure it's possible that if you had super lightweight material for all the dry
mass, 3 stages would make more sense.

You're right, there is a "real-world tradeoffs between efficiencies in the
rocket equation and engineering parameters". This trade-off is unfavorable to
SSTOs.

------
adolph
_The Space Shuttle was considered a reasonably conservative design using a lot
of existing technology. Despite this, it had cost overruns north of a billion
dollars, and it was late by several years. Chrysler 's more unconventional
layout would've probably cost even more, and been delayed even longer._

This counterfactual is directly related to the mindset that led to the
“conservative” option going upside down value-wise. Instead of viewing the
difficulties as being opportunity, the nation chose to play it safe. It lost
the attitude towards doing things “. . . not because they are easy, but
because they are hard, because that goal will serve to organize and measure
the best of our energies and skills, because that challenge is one that we are
willing to accept, one we are unwilling to postpone, and one which we intend
to win. . .”

[https://spacecenter.org/exhibits-and-experiences/starship-
ga...](https://spacecenter.org/exhibits-and-experiences/starship-
gallery/kennedy-podium/)

~~~
valuearb
I’d argue the Shuttle failed because it wasn’t conservative enough. What we
needed was more cost effective versions of the Saturn rockets.

Instead they got infected with the SSTO fantasy, which can never work well.
But it boxed them in a corner with the wrong fuel, wrong engines and forced-
them to add super expensive SSRBs, which required putting the Shuttle on the
side, which led to two disasters and a “reusable” launch system that had to be
totally rebuilt between launches.

We’d still have Skylab if they had focused on manufacturing efficiencies for
Saturn rockets instead.

~~~
pfdietz
In an alternate universe, the Saturn IB could have been evolved to something
like the Falcon 9. The H1 engines are in a similar thrust class as the Merlin,
although with lower performance.

~~~
Breza
I've thought about this as I've read the book Coming Home: Reentry and
Recovery from Space. The fixation on a space plane probably set back the US
space program by decades whereas a more boring evolutionary tree descended
from the Saturn program would have been interesting.

------
orbital-decay
This design was also radically unrealistic, due to the shape in particular.
Fighting your own reentry decelerator on your way up is a ridiculously
ineffective way to reach space, for one. Spike engines are also suboptimal in
many ways, the cost isn't exactly the reason they aren't used.

~~~
TheOtherHobbes
Would it even reach orbit? The drag beyond Mach 1 must be huge, so the
compression forces on the "saucer" would be huge too.

~~~
rbanffy
The path up is mostly vertical in the densest atmosphere, while the
deceleration part is as horizontal as possible. It is fighting the saucer on
its way up, but it's nowhere near as effective as it is when used correctly on
the way down. I'm pretty sure the Boeing engineers ran the numbers on this one
before proposing it to NASA.

~~~
valuearb
There are plenty of paper launch systems that engineers have run numbers on
showing they could work, that won’t work in practice. This and VentureStar are
two examples.

In this case it’s not the shape as much as carrying way too much extra/dead
mass, jet engines, aero spikes, and using a LH2 means much more massive
tankage requirements.

------
jonplackett
In the CGI rendering of how it would have worked - I was surprised the whole
thing made it into space.

I thought it would just be a booster like Falcon 9.

------
coldcode
I still wonder about another radical idea: launching payloads (not people
obviously) via a long ramp with some kind of magnetic accelerator and flinging
them into orbit. I forget what this idea was called.

~~~
throwanem
"Mass driver".

~~~
rbanffy
The ramp needs to be very long or we'd need to build a very rugged spacecraft
- enough of its brains and propulsion would need to survive the acceleration
and the aerodynamic losses on the way up in order to circularize the orbit and
not cross the ground on its way back.

Which brings a very scary failure more - being hit by the payload that is
mostly dead, but coming back to the ground at near orbital speeds.

~~~
growlist
I think the hardening is pretty well understood - just fill any sensitive
electronics etc. with resin and it's pretty much solved. But the heat problem
certainly is not, and obviously humans, not being particularly amenable to
being filled with protective resin, would be completely pulped without
ridiculously long ramps.

I'm interested to know whether anything ever comes of this:
[https://www.wired.com/story/inside-spinlaunch-the-space-
indu...](https://www.wired.com/story/inside-spinlaunch-the-space-industrys-
best-kept-secret/)

I'm sure I recall reading something on a forum somewhere from an anonymous
former employee that claimed Spinlaunch was a mess and would never work.

~~~
csours
This all reminds me of "The Moon is a Harsh Mistress"

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wwarner
This is an amazing engine design!

~~~
dwd
Everyday Astronaut has a lot of material on aerospike engines.

I would question whether NASA didn't think they were still in the game or
whether politics and pork-barrelling influenced whether they were in line for
funding. Shame they didn't try and self-fund developing the engine.

~~~
valuearb
The added weight of every aero spike engine ever made obviated its performance
benefits, even for SSTO. SpaceX has always focused on super high thrust to
weight ratio engines (Merlin and Raptor) and that (along with lighter tanks)
has more than offset the lower ISP of their propellants.

~~~
pfdietz
Indeed. There are ways to get altitude compensation in more traditional bell
nozzles.

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mLuby
> The YouTube channel Hazegrayart created an incredible CGI rendering of what
> Chrysler's craft would've looked like, and how it would've worked.

[https://youtu.be/___JNGJog0A](https://youtu.be/___JNGJog0A) (4min, amazing
channel BTW.)

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GermanDude
Well, what about properly designing the Fiat, first?

