3D-printed Aerospike Rocket Engine | Hacker News Reader

3D-printed Aerospike Rocket Engine

kickstarter.com

60 pointspnr40 comments

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.

>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.

(1) There are a few of us. It feels good to be associated with something breaking ground in this field.

(2) This could be a demo, a proof-of-concept. Those are useful in later attracting investment, or at least attention which can be later translated into capital.

RE (1): Sure there are a few people with extra money (judging from your HN profile you are one of their Bagaveev's ideal candidates), and it is really exciting to be involved in new projects. It's more exciting to be involved while potentially making money or to get something more than a feeling of satisfaction.

RE (2): Valid point. Successful Kickstarter campaigns often raise more funding afterwards. But I still think they would like to say, "look at all these people who were willing to risk money by investing in our company" rather than saying, "look at all these people who threw us a bone when we asked for it." Both statements demonstrate an amount of attention, but I think the first is better information to future investors than the second.

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.

These are all things I wasn't even thinking of. They would be great reward tiers. I would love to send a little data logger into space just so I could have my own personal data from space, kind of like the ArduSat Kickstarter. I'm not sure if it would be feasible, but if the price was under $1k for a smartphone sized package I'd go for it. Even if it was timesharing my code with someone else's to make it feasible. I'd pay more for a higher chance of success, but given the two year lead time and unknown chance of success I'd want a discount.

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.

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

I am the creator of this Kickstarter project. Upper stage without lower stage is certainly not reaching space. We didn't want to give people false hope. And the project there is mostly for a promotion, since we're fundraising in Boost accelerator before demo day

This is fund-my-hobby, albeit a cool hobby. FYI most universities with large aerospace departments have some type of rocketry club developing similar scale motors:

http://spase.stanford.edu/Hybrid_Rocket_Student_Meeting.html

http://web.mit.edu/rocketteam/www/lab.html

http://www.umich.edu/~mrocket/archive/hybrid_i_photos.html

Last link shows some people I know personally, now at SpaceX.

I am the creator of this Kickstarter project. Kickstarter mostly is used to promote the project. We're actually in fundraising mode in Boost accelerator before Demo Day 11th February. I agree with you that Kickstarter is not the best venue to raise money for highly technical project.

Ah, that explains why the Kickstarter page looked so..., well, sloppy. (No offence.) It seems as if one requires an entire marketing department to start a "proper" kickstarter these days.

This was done mostly to attract attention and publicity. Our team at Boost accelerator is fundraising 500k.

ahh. Was gonna email you telling you to offer ad spaces on your rockets (and/or classes) as reqards for the bigger contributions. Would attract corporate ppl.

(Not sre what kickstarter's ToS have to say about this though)

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...

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

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.

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/

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.

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

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.

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

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...

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.

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...

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.

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.

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.

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 :)

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/ - 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.

A heat sink engine could work in pulsed operation.

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

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

Hi. Theoretically yes, and we started there, but as someone mentioned, it has really low efficiency and will work only for few seconds. It would be expensive, and people are likely to stick with solid rockets for heir simplicity.

is it subject to ITAR?

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

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.

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

Can ITAR apply to open source projects? i.e. if someone starts an open source rocket engine project not in the US, are people based in the US allowed to contribute in any way without running afoul of ITAR?

I don't know. When I was in university we had similar projects going on (scratch-fabricated hybrid rocket motors, not aerospikes though) and I know there were non-citizen students participating. Didn't seem to be a problem.

I think the issue would be that they intend this engine to be the upper stage of a satellite launch platform. ITAR kicks in when you get up to that capability I believe.

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

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

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