A startup named X-Bow Systems has received a $17.8 million contract from the US Air Force Research Laboratory to demonstrate additive manufacturing technologies for solid rocket propulsion.
The three-year contract, announced Sept. 26, is part of a $60 million agreement announced in April known as a strategic funding increase, or STRATFI. X-Bow’s contract includes $30 million in U.S. Air Force funding and $30 million in matching funds from private investors. AFRL’s $17.8 million contract covers a portion of the government’s share of the agreement. [$17.8 million out of $30 million is around 59% of it - SiG]
The AFRL has a program going called Rapid Energetics & Advanced Rocket Manufacturing (RE-ARM), intended to help reduce the cost and schedule to produce propellants for tactical rocket motors.
X-Bow CEO and founder Jason Hundley said the AFRL contract will help mature the company’s manufacturing technology and processes. The company has been working on solid rocket technology projects with AFRL at Edwards Air Force Base, California.
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A solid propellant production line that traditionally would take anywhere from three to six years to stand up, “we’re looking to do that within 12 months” and at much lower cost, Hundley said.
Hundley went on to say that they've designed their process to work with any size Solid Rocket Motor from “... from the 2-inch diameter level into the 60-inch plus diameter level.” The company hopes to eventually compete for contracts against established solid rocket manufacturers like Northrop Grumman and Aerojet Rocketdyne, which was recently acquired by L3Harris.
April 2023 test of an X-Bow Systems additively manufactured solid propellant. The source article doesn't say how big that SRM is, but judging by the screws and other hardware visible on the test mount, it looks closer to 2" than 60". Image credit: X-Bow Systems
This looks like a fun project for the home experimenter. Print solid rocket motors out of some sort of liquid that hardens into the proper size and shape as it cures; perhaps print a ceramic nozzle on it. I'm pretty sure I can't be the only one around here who played with model rockets, over 50 years ago in my case. I'm thinking of the little solid-fuel rocket engines we used back then. I'm sure these need to be higher performance, which means they need to be in metal tubes rather than cardboard.
Interesting that L3 Harris is The Harris Corporation that I knew of from living in Brevard County in the late 70s. Glad to see they survived the fall of the Shah of Iran (when the Shah fell, Harris was just about to deliver a whole bunch of radar and communication systems, including mobile comm systems to Iran. And they took it in the neck over the money they didn't receive. And, of course, they now had all that equipment sitting in inventory that couldn't be sent anywhere else without lots and lots of work.)
ReplyDeleteAs to 3D printing, doesn't SpaceX already do that with their Draco thrusters? I know, not solid propellant motors, but still, the tech has been around for a while.
They've been here all along. Corporate headquarters and a bunch of different divisions. All told, I worked there 13 years, with the usual layoff mixed in at a couple of years. They were my second to last job.
DeleteI go back to the day they were Radiation Inc, long before Harris bought them. I was a kid, but knew many of their engineers thru my dad. Got to access some areas of the Cape off limits to ordinary civies. Back in the 60’s of course.
DeleteIn the very early days of 3D printing, the first printer I encountered used a powder that an Epson printhead sprayed a solution on to the powder (a fixitive was in the print head, composition unknown) , then a fresh .007" layer of powder was scraped over it and the printhead did the next "layer". I still have some of the 3D objects that were printed as examples. One was a bolt and nut that was printed together (the nut was screwed on the shaft when it was printed!) and all you had to do was pull it out of the powder in the build tank and shake it off to get rid of the powder. It was made from starch! Danged if I can remember the manufacturer...
ReplyDeleteI'm thinking that a solid rocket motor could be printed in such a manner. Easy-peasy if you can find an inert fixitive along with a finely-grained powdered solid fuel! Takes a few minutes to make small and medium motors...
See:
Deletehttps://en.wikipedia.org/wiki/Powder_bed_and_inkjet_head_3D_printing
for a diagram of how it works. Note the date/year that some bright boy at MIT developed it!
Ah! It was the Z-Corp printer.
DeleteI gotta look that up. I envisioned something like the way they print concrete buildings; they print the concrete as a liquidy or pasty, kind of thing and as it hardens it becomes like poured concrete.
DeleteTech Ingredients, a YT channel by that name, has a very good series on different types of propellants, nozzle shape, and just about everything needed to know in rocketry.
ReplyDeleteEverything is off the shelf DIY.
Found the channel (the easy part) and have an hour long video queued up.
Deletethey are printing the fuel. rather than pouring the ingredients into a mixer and pouring the sludge into tubes, they directly print the fuel. allows more precise control of the reactions, greater reactivity / combustion force.
ReplyDeleteI would think this technology could build solid fuel motors with continuously varying grain geometry in long lengths and eliminate segmented engines that require seals like the infamous O ring gas seals which failed in the Challanger SRB.
ReplyDeleteA bit on solid fuel grain geometry here:
https://www.nakka-rocketry.net/th_grain.html
My knowledge of solid fuel grain geometries is pretty much that they exist and can control the thrust vs. time curve, but not how to derive those. I thought the reason for stacking the STS SRBs was because they got shipped cross country and continuous, 150' long tubes weren't possible to ship by rail.
DeleteI suppose that compared to the blades for a wind turbine they'd be easy to ship.
Not to beat a dead horse, a quick search of the web revealed some interesting facts about the segmented SRB.
DeleteOne is that the Aerojet design submittal was a non segmented booster that NASA rejected
Another is that the segmented design was to enhance reusability.
And as you suggested transportation load limits was another.
And last of course was cost. The segmented design was a lower cost option.
Studying the history of this program, and all others in aerospace, electronics, chemistry and physics, weapons and warfare keep me up at night, as much as Ham Radio. That and restoring the mountain of older HP and Tek instrumentation of yesteryear I keep accumulating. (Yawn)
https://space.stackexchange.com/questions/60791/why-were-they-using-segmented-boosters-on-space-shuttle#:~:text=Bottom%20line%2C%20segmented%20cases%20were,one%20of%20the%20segmented%20designs.
https://www.latimes.com/archives/la-xpm-1986-02-15-mn-8154-story.html
Maybe we should switch to email, although it's borderline impossible for me to know if anyone is following this.
DeleteNevertheless... the one that stood out to me was: "Another is that the segmented design was to enhance reusability." It stood out because I don't see why that would be. The recovered SRBs were stripped of their insulated coating - I heard it called cork but maybe it just looked like it? - and cleaned inside and out. It's not like they got filled with new propellant there on the Cape, they were shipped back to the factory in Utah, practically across the country. I don't see why shipping segments cross country vs. the single piece booster would enhance reusability, ignoring those tradeoffs of needing to be segmented due to tunnels and other design realities of railroads. Which gets back to the story by the "Railroad Historian" in the longer link above.