3D printed metal rocket engine contest Update

I’d like to share how the 3D printed metal rocket engine contest is going:

The deadline was moved back to June 30th. The objective is to design an open source 3D printed (in metal) regenerativly cooled rocket engine for use on a nanosatellite launch vehicle (1-10kg payload). 3D printing in metal is an available technology and it has been demonstrated with regenerativly cooled rocket engines before. I’m submitting the design on a second stage LOX/Propane engine with around 800 lb of thrust. (It will be a sea level version for testing.)

I don’t mean to disparage the competition but as far as designing goes our team is pretty much stomping on them. I can say that because before you even look at any calculations for the engine just from a basic configuration standpoint all the other teams are non-starters in their current form. Although some show potential and I commend their effort. For example to make an engine like this you are going to need injectors, regenerative cooling channels, and film cooling, but we are the only team with all three. Only about 4 teams even have injectors designed at all, and only one other team looks like it could work. One team has what is supposed to be a pintle, but from the looks of it they’ve never seen one before. One team has oxidizer inlets but no fuel inlets. Only 2 other teams even have regenerative cooling channels, and we are the only team so far that has film cooling. We’re also the only team so far to mention how we will deal with some of the practical aspects of even just a static test, like LOX valves, flow metering and how to get a hold of cryogenic propellants. I’m no Wernher von Braun but these guys have a lot of catching up to do.

However this advantage does not assure us we will win for two reasons. First, the design is oddly only worth 40% of the overall evaluation the other parts are 40% collaboration and 20% business plan. So we even if our competition has lousy rockets engines they could win simply by blathering to one another more and writing a convincing business plan. The second reason, which incidentally makes the first more troubling, is that while the judges have technical backgrounds they have no rocketry background that I am aware of, so I don’t know if they would know a good rocket engine if they saw one. One judge is known for having built an IEC fusor in high school. Another is an artist, a biologist, and a “space researcher” whatever that means. The third is the guy who designed the Segway (not the later CEO of the Segway company who fell to his death when he rode off a cliff on a Segway.) Although he has some legitimate engineering background (I mean other than the Segway) he is also the co-inventor of a pneumatic swat team cannon. That’s not a cannon used by swat team members to shoot at things, it’s a cannon that shoots swat team members out of it and onto roof tops, over walls, and to any other hard to reach place that you would like to have a swat team. I don’t know if he will recognize ‘realistic’ and ‘practical’ when he sees it. Maybe I should have gone with a rocket catapult to orbit instead.

This makes our job more difficult and winning uncertain. This means that in our design notes we also need to explain and justify a lot more than if we had judges that we knew were familiar with what it takes to make a liquid propellant rocket engine. We can’t simply state how much propellant we plan use for film cooling. We also need to let them know that if you don’t use film cooling at all you can expect a destructive engine failure. That way they are less likely to overlook our competitor’s flaws.

I’m confident about our design, and I’m sure our business plan will be good as well, but I could use some help on the collaboration part. Just some back and forth comments on the collaboration site they want us to use should go a long way. Even if you know nothing about rockets the conversation would be beneficial and it would be appreciated.

The prize for winning is 5,000 dollars plus they will print the winning engine for free. For our current configuration at the vendor they intend to use that’s about another $5000 worth of 3D printing. If we win we plan to spend the money on things we would need for a static tests of the engine like a load cell, some tanks, helium, LOX ect. I think that if we won we might be able to have it ready for static testing at the October launch. If there is money left over we’ll put it towards a launch vehicle. (I intend to develop a scalable process that we could use to make pressure vessels from scratch.)

Win or lose, I want to turn some of the worked we’ve done on this into some RRS News articles, should we reboot the RRS News. I’ve done some programming for this that there may be some interest in sharing. I’m working on a program that sizes a launch vehicle based on payload, and another one that will give the basic chamber and nozzle configuration and do a basic thermal analysis. I also hope to work on a program that will analyze the rockets ascent trajectory. If you then take those 3 programs and put it all into an optimization scheme, like the evolutionary optimization program I wrote in college for turbopump design, you would have a launch vehicle design optimizer that can be used to help find the smallest and lowest cost launch vehicle configuration that could reasonably be pulled off. Neat huh!


-Richard Garcia

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