
3D-printed Aerospike Rocket Engine - pnr
https://www.kickstarter.com/projects/1108292587/3d-printed-aerospike-rocket-engine
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olympus
I'm not sure this is really a good fit for a Kickstarter project. I love
rockets/space/science/etc and fully support researching cheaper launch
methods, but for most people to invest, they want to get something back. There
are very few people who will/can donate to something on a purely altruistic
basis. These guys aren't a charity and I can't even get a tax write-off.
Pushing a button, while cool, is not really a return on investment and only
rocketry enthusiasts with extra money (a rare combination) will be willing to
pay for that. The cheaper reward tiers offer a "Master-Class on 3d printing
and rocket science" which will have more backers due to the 3d printing
information but probably not enough to clear their goal.

I think a better way to spur investment would be offering a reward tier that
gives a portion of the company (i.e., a $x investment gets you a y% stake in
the company). This is just selling stock in a company off of Wall Street and
probably a better fit for a company that isn't offering services or a physical
product to the general public. I'm not sure what kind of regulations you have
to follow (or if kickstarter would even allow it) but it would certainly open
up the field of potential backers to include the folks that know/care nothing
about rockets but would like to make some money when the company is inevitably
bought out by a larger space launch company like SpaceX.

~~~
infogulch
How about sending your photo to space and recovering it?

What about sending any tiny object (with weight and size restrictions) into
space and recovering it?

The higher levels could offer to send a small custom payload into space (if
not orbit) e.g. a smartphone with sensors.

The first two would be more for the novelty (this ring was in space!), where
the last might be for a university project or something.

~~~
WiseWeasel
And at the $50,000 tier, we'll put a 10" wrench with your name on it into the
same orbit as your favorite NRO satellite.

~~~
infogulch
There's a big difference between getting something "to 'space'" and getting
something into orbit. More than 28,000 km/h difference.

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butThenAgain
I'd be enthusiastic about nano-satallites, if the space-fairing component of
human civilization had established reliable processes for keeping low earth
orbit clean and free of orbiting pollution, debris and junk.

The last thing we need is more high-velocity objects being randomly inserted
into orbit by hobbyists, when there's no reliable means to clean up the
objects left in orbit by predecessors.

[http://images.gizmag.com/inline/space-debris-kessler-
syndrom...](http://images.gizmag.com/inline/space-debris-kessler-syndrome-
nasa-debrisat-7.jpg)

How about a startup/kickstarter that harvests existing space junk, instead of
one that encourages people to haphazardly produce more?

~~~
nadirkazan
I am the creator of the project. We are not expecting to launch nanosats
higher than 400 km. or 600km in case of Sun Synchronous Orbit. All these
nanosat orbits will degrade in 1.5-3 years and reenter and burn up in
atmosphere.

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Cogito
This is really cool.

I would love to see more details about how the engines are 3d printed, and the
plans for the designs. Will these engine designs be open sourced?

Also, the rewards are a little difficult to parse. A list format would
probably be easier to read, rather than one sentence with each reward
concatenated to the rest with 'and'. I think having the 'all previous rewards
plus ...' is a better format as well, but that is more personal preference.

[EDIT]

Further, there is no break down of how the money will be used. It seems like
'give us money and we'll do cool things with it' but without any clarification
of how much money is really needed to do those cool things.

[EDIT2]

There is a pretty amazing blog over at Rocket Moonlighting [0] that contains a
lot of details around 3d printed rocket engines. Well worth a look.

[0]
[http://rocketmoonlighting.blogspot.co.nz/](http://rocketmoonlighting.blogspot.co.nz/)

~~~
nadirkazan
I am the creator of the project. It is unlikely that plans and designs will
ever become open sourced. Considering experience of DefDist and their issues
with State Dept because of open plans of "Liberator" gun, we are being careful
not to expose designs to outside of United States.

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johlindenbaum
After being on a team that was launching cube sats with old ICBMs this
reusable launch platform for science excites me!

~~~
Crito
Yeah, this is obviously a _very_ highly ambitious project, but I think that it
is the _right sort_ of ambitious. Even if their ultimate plans don't come to
fruition, it should be very interesting to see what they accomplish. This is
the sort of project where the journey is as exciting as the goal.

I'm a little surprised to see that they are going with pumped LOX instead of
pressure-fed. With engines that small I would have expected the extra hardware
to be a poor tradeoff.

~~~
nadirkazan
I am the creator of this project. We are doing pump-feeding because we have to
grow as designers and analysts. First stage engines are going to be 9 times
more powerful and will definitely need pumps. It is way better to mitigate
risks by designing small scale low-risk propulsion system early

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Gravityloss
Pet peeve: this is a spike nozzle, not an aerospike.

The aerospike engine has a truncated physical spike that is extended by an
"aerospike" that is formed by the pressurized turbine exhaust.

It's still crude and early, but it's very nice that people are actually
building rocket stuff! Too bad ITAR is a problem...

~~~
avmich
I think you're wrong. Spike nozzle has the spike which extends the whole
length until flow from different sides converges. Aerospike is truncated but
the circulating gas doesn't need to come from turbine; neither X-33 nor Spiral
projects dropped turbine exhaust through the spike.

~~~
Gravityloss
NASA CR-1998-207923 The Control System for the X-33 Linear Aerospike Engine by
Jerry E. Jackson, Erich Espenchied, Jeffrey Klop

"A secondary flow (turbine drive gases) is exhausthed throug the nozzle base
and adds to the recirculating flow to increase the base pressure and the
overall nozzle efficiency."

[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/1998017...](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980174934_1998118014.pdf)

Had to curl it, since pdf.js always froze before loading it. For some reason
the column layout is broken so quoting the text required quite a lot of hand
editing.

~~~
avmich
Thank you. However, turbine exhaust can't provide much thrust - both flow and
speed aren't large. So the spike nozzle doesn't get much thrust from turbine
gases - yet it can get it from chamber gases.

~~~
Gravityloss
Which was not my point. Low pressure turbine exhaust gas serves a purpose.
Hence the whole name of the engine, "aerospike".

It's not very important, it's just names. This project is hardly the first one
to not distinguish between spike nozzles and aerospikes.

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Geee
Hey nadirkazan. With 3D printing, could it be possible and affordable to make
really tiny rocket engines for other uses, like radio controlled flying
things? I'm thinking something like a moon lander, but smaller (really small,
quadrocopter size). I would buy that :)

~~~
avmich
The problem is not so much building as it is cooling small engines. Scaling
works against you here. You can download a good simulating tool for liquid
fuel rocket engines - [http://www.propulsion-
analysis.com/](http://www.propulsion-analysis.com/) \- it will show how, when
you're decreasing engine size and fuel flow it becomes not enough fuel to cool
of the engine.

Spike nozzle is particularly problematic around the throat, which has bigger
area than for a regular bell-shaped nozzle.

~~~
Gravityloss
A heat sink engine could work in pulsed operation.

~~~
avmich
True. However this mode isn't very useful when you need to lift something from
Earth - or just to keep it in the air.

~~~
Gravityloss
You could have a glider. Or a boost-glide vehicle to be more precise.

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VladRussian2
is it subject to ITAR?

~~~
Crito
Almost certainly, unless they are not operating from within the US:
[http://www.fas.org/spp/starwars/offdocs/itar/p121.htm#C-IV](http://www.fas.org/spp/starwars/offdocs/itar/p121.htm#C-IV)

~~~
VladRussian2
when in US the ITAR still applies AFAIK - getting any access to or knowledge
transfer from ITAR project to non-US person, etc... Looks like starting from
1K plegde - invitation to test fire the engine - may run afoul of it.

~~~
Crito
Yes, that is my understanding. I believe that unless they are entirely non-US
based, this would be subject to ITAR.

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mkw5053
This timeline is not realistic. No discussion of a control system at all for
guidance and (more difficult) stability.

~~~
nadirkazan
This project is for engine only. We are separately raising 500k to build a
rocket and develop our GNC software.

