We are LPRD Rocketry. We Build Rocket Engines.

Hello all,

Welcome to an incredibly special and momentous update for LPRD Rocketry! We are finally celebrating our transition from “some random kids who want to make liquid propellant rocket engines” into a group which has proven its ability to design, build, and operate liquid propellant rocket engines. Few people can claim this feat, so for those of you who have been through the crucible with me, I congratulate you.

(Full test video is at the bottom of this post)

For those of you who haven’t heard of us before: We are LPRD (“leopard”) Rocketry. We work with the belief that dreams should be pursued fervently and pursued now. We are a group of students at the University of Minnesota – Twin Cities and other Minnesota colleges, and our dream is a dream we think is shared by the human race. Ever since people have been able to look up at the heavens, the stars have been a source of wonder. We want to contribute to the engineering body of work that will allow humanity to expand to that final frontier. Specifically, we aim to use the engineering skills of students to design, manufacture, and test liquid propellant rocket engines, and we invite you to join us.

In the beginning…

When we started about a year and a half ago, we were just three people with a little curiosity. Hobbyists build model rockets all the time; some even make their own rocket engines, but they always use solid propellants. Why don’t amateurs build liquid propellant rocket engines? We decided to find out.

We started small. Fall of 2014, we started by building some out-of-the-box hobby rockets and designing a test stand which would let us practice handling commercial-off-the-shelf (COTS) solid propellant rocket motors.

And then there were 20…

Then the real work. We expanded to a team of about twenty and began the task of designing and building our own little rocket engine and test stand. Rocket engine design and manufacture progressed quickly. Laborious, yes, but straightforward. We hammered out a few dozen hours in the machine shop, and out came an engine.

Elliot of LPRD rocketry looking under a bridgeport for a lost screw while machining

Pictured: not the usual method

But the path was hard…

The delay occurred in the test stand. Piping, plumbing, and valves are hard. Not sexy, but hard. We made some poor hardware choices, and that set us back. I won’t lie, the delay frustrated me. Some of our operations were scary. Pressurized gases are scary things to a college kid who’s never dealt with them before and is suddenly figuring it out on his own.

Some LPRD members hard at work on the first assembly of the test stand

Some LPRD members hard at work on the first assembly of the test stand

And we struggled…

When summer came, we still had no real product. Just an engine and a partially functioning test stand we could use for cold flow rate and pressure testing.  Safety approval became an issue as well. Professors wanted nothing to do with it, since no one at the University of Minnesota specializes in rocket engines. The UofM College of Science and Engineering wanted nothing to do with some kids playing around with trying to light a home-made, untested, highly risky rocket engine.

Many people dropped out, and I don’t blame them.

And then there were 5…

The believers (or those of us stupid and stubborn enough to keep doing this) spent the summer working doubly hard in reduced numbers to pressure test the engine and make sure it would withstand the structural strain we would eventually put on it.

Then, we caught a break. We talked to Orbital ATK‘s TPG (back then, it was ATK’s ATPG) about using their facilities to conduct test firings since the University wouldn’t have anything to do with it. The project excited them, and they wanted to help us to a test firing.

The only problem? Our test stand setup wouldn’t let us fully fire the engine. The test stand wobbled, only had on-off control, and the valves moved painfully slow. We couldn’t do any more than an ignition test, but school started in a few weeks, and if we didn’t have anything to show for 6 months of work, how would we recruit for a dying project? We either had to create something out of nothing, or die as a project.

And so we created something out of nothing.

Something, but barely a result.

That day, we made mistakes. Many of them. In front of professional test technicians whose job it was to not make mistakes as they set off explosives.

As soon as we got there,  we accidentally shorted together our batteries and set our lines on fire. Two, twelve volt, lead-acid ATV batteries designed to output more than 300 Amps of current shorted together. Thick clouds of pungent smoke roiled out of our battery box. Luckily, the fire burned out, harmed no one, and the proving grounds had a backup power source into which we hooked our control panel. Regardless, we made mistakes and made barely any progress when Orbital ATK donated their time to help us fire a rocket engine, so we knew we had to do better.

So we came back…

We hyped the video, recruited and expanded our team again. We purchased new valves, we tested those valves, and we discovered those valves were the wrong valves. And then we did it again until we found acceptable valves.

LPRD team members smiling at camera during wet test while holding fire extinguisher

Concurrently, we began designing a second generation engine which would be regeneratively cooled, meaning we wouldn’t have to pump water to it to keep it from melting.

CAD Model of LPRD Rocketry regeneratively cooled rocket engine chamber designed for 3D printing with single spiral coolant fuel channel

And suddenly, things started happening…

Our team grew. We built our first high power (solid propellant) rocket as a testbed for our avionics.

LPRD Rocketry flight subteam as of January 2016 having almost completed their first ever high power model rocket

The LPRD Rocketry Flight Subteam

We contacted Protolabs about 3D printing our regeneratively cooled engine, and they decided they would like to donate the piece.

Glen Smith holding LPRD rocketry's 3D DMLS printed engine done by Protolabs

Printed Engine!

We started designing and testing our own, custom injectors.

We partnered with the student group Material Advantage to begin designing and prototyping a ceramic rocket engine.

LPRD Rocketry ceramic rocket engine prototyping mold

We talked to the Minnesota Space Grant Consortium and received some workspace and some funding.

But none of this matters if we don’t have anything to show for it.

So we scheduled a second test with Orbital ATK at the proving grounds and began preparing.  Hours and hours of dress rehearsals consumed our time and brainpower as we found issues, fixed issues, discovered new issues, and fixed those issues.

LPRD Rocketry members during dress rehearsal making last minute modifications to test stand

We ran dress rehearsal nine days from testing day, and we were nowhere near ready. The ignition system was not assembled, the engine was under modification, and the procedure had flaws. This is the time when Dreamers fall away and Doers pull through.

LPRD Rocketry test stand terminal

We pulled it together. We showed up, we delivered, and we ran the first successful liquid propellant rocket engine in Minnesota.

We are a group of students, not professionals. We attend a school with no aerospace propulsion lab. We are a group of dreamers, of believers, of doers. We are LPRD Rocketry. We look up at space, and we see endless potential. We look around us at the other students, and we see endless potential. We don’t want to wait for a diploma to do real engineering and create something real. We don’t want to hear that we’re too young, too inexperienced, to naive, because we know we are.  We also know we always will be thus unless we go out and learn by doing.

So we did.

Sound like you identify with us?

There’s a long path yet to tread. There’s work to be done, and it will be hard. Some of it will be tedious, even boring. Some of it will be exciting and experimental. Some of it may even be dangerous, but I can guarantee you that all of it will be hard. That’s what sets us (and maybe you) apart. We choose to do this not because it is easy, but because it is hard. We do this because we are LPRD Rocketry.

When we come out the other end, we will be more experienced, smarter, stronger, and more ready to help solve the engineering challenges the world currently struggles with.

Still identify with us? Then I’d like to invite you to join us in our journey.

David Deng
Project Manager
LPRD Rocketry

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Update 3/20/2016 – Fire Burning, Fire Burning

Hi all,

Hope you had a fantastic Spring Break, those of you at the University of Minnesota. LPRD Rocketry was definitely very busy during the break, as you can see below!

LPRD Rocketry Mk 1 engine first full successful firing on test stand at Orbital ATK

First full firing of an amateur-built liquid propellant rocket engine in Minnesota (we think!)

We have some very low quality video, but that still needs processing and we’re waiting for the high speed footage to arrive, so no videos yet. Due to policy, we are not allowed to take our own media at the testing site, but Orbital ATK’s technicians certainly took a bunch and will be sending them on their way. Look forward to those on the next blog update though! We know. We’re such a tease.

The ceramic rocket engine was unfortunately not prepared in time due to some unexpected manufacturing complications, but we had a successful firing of our first generation engine nonetheless.

University of Minnesota Material Advantage LPRD Rocketry ceramic rocket engine manufacturing attempt failed torsion

Pictured: “Complications”

This marks a big step in the development of LPRD Rocketry from “those crazy kids down the street” into “proven manufacturer and operator of liquid propellant rocket engines”, which is an amazing thing to be able to claim. We definitely want to thank Orbital ATK’s TPG proving grounds for their help providing a safe location from which we could run these things.

This is exciting stuff, and I’m glad you’re here to experience it with us! This week on Saturday, we will also be launching our own (solid propellant) high powered rocket for the first time to trial some avionics/telemetry components. Wish us luck!

David Deng


Subteam Spotlight: Flight

The flight subteam’s work so far has been in two different areas. First, constructing a high powered solid rocket which will serve as a testbed for our avionics. This rocket is almost ready to go and will be flying (and with any luck, landing) on March 26th. This will let us develop our capabilities flying simple, COTS (commercial-off-the-shelf) rockets and test out the avionics which we will eventually use on our liquid propellant rocket. Glen is currently putting the finishing touches on the rocket, and we’ll soon be ready to go. Videos to follow (we hope).

The second area is slightly more interesting. If you remember from the post five or six weeks ago, we’re experimenting with an “asymmetric thrust” configuration for our rocket engine. Sam Lijo and Vadim Stavitsky (a new member) have been working hard trying to design a passively stable rocket which still allows us to have differing magnitudes of thrust for different durations from two different engines.

Member Spotlight: Lucas Kramer

Lucas Kramer of LPRD Rocketry

My name is Lucas Kramer, and I am a first-year graduate student in Computer Science.  My primary research interests are in programming languages and AI, but I am also interested in embedded systems and some electronics.  I have a strong interest in spaceflight and rockets, and I am considering working for an aerospace company eventually.  

Lucas Kramer of LPRD Rocketry

I joined LPRD to get hands-on experience with a project like this that will be greatly helpful in industry someday.  This project also lines up almost exactly with my interests – I had previously considered attempting building a small liquid fueled rocket engine myself, but lacked the resources.  I have also previously been involved in the UMN solar vehicle project, as well as the MnSGC High-Altitude Ballooning team, where I gained valuable skills in electronics design and embedded software development.  

One interesting fact about me is that I am 16!  I was homeschooled and attended college early through PSEO, allowing me to graduate last fall.  I am now starting the Ph.D program in CSCI this year.  

Lucas Kramer of LPRD Rocketry

Someone who has been a major inspiration for me is Elon Musk.  He has shown that you really can become an expert in any area, even if everyone else thinks you are crazy, and that the solution to a challenging problem might be hiding in plain sight.  Also, keep going when things are hard!  His companies have also given me hope for the future of humanity, and really got me excited for things like space travel.  I would gladly go to mars someday if that is an option!  One of my dreams is to work toward this goal.  

Lucas Kramer

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Update 3/5/2016 – Devil in the Details – That’s Why We Dress Rehearse

Hi all!

We’re at T-12 days from our test firing with Orbital ATK. We ran a stressful (but somewhat successful) dress rehearsal this Saturday and a much less stressful test readiness review today (Sunday). As we began the day, the Avionics guys realized just how much detail work and building still needed to go on before we had a functional test stand. Igniter boxes needed fixing; data collection systems needed setup, boards needed soldering, etc etc etc. All “easy” stuff to do, but time consuming and detail oriented, and the things us engineers tend to skip in our excitement to solve the big problems. The first four hours of the day were spent on that, but we eventually got around to what we needed to do.

LPRD Rocketry members during dress rehearsal making last minute modifications to test stand

Making last minute modifications to the test stand

Not only did we run our dress rehearsal, but we also incorporated new, stainless steel components into our test stand to make it more robust and temperature resistant. From the front, the stand looks a bit… well… aggressive. Gone are the soft white nylon tubes. Over time, the test stand has changed and changed. Of our original test stand created a year and a half ago, only 6 pieces remain. Eventually, those pieces will probably be exchanged as well, which leads to the question: is it still the same test stand? Is it still Theseus’s ship?

New LPRD rocketry horizontal test stand front view looking more aggressive with its stainless steel hosing

Philosophical musings aside, the mechanical components of the test stand are ready to go, but we still have several electronics hiccups we need to sort out, and the Avionics subteam will be busy on that all week. Lucky we caught it now as opposed to the day of the test!

David Deng

Subteam Spotlight: Avionics

As was previously mentioned, we have started working on wireless controls and wireless telemetry. For the wireless controls, we have prototyped relays run by MOSFETS that are currently operated by an arduino which will be swapped out with an Atxmega chip in the future when we make our own boards. More specifically they will be AtxMega32A4 and once these are programmed, the code will be uploaded onto our github page from which it can be accessed. Also, we are currently designed breakout boards for these chips.
LPRD Rocketry's Ginny working on creating a breadboard for use on our avionics

We have put together a small board to be sent on our next solid flight that would fire black powder charges and also trigger a parachute when the rocket reaches around 500 feet. This is facilitated by an altimeter on the board.

Eggtimer Quark used by LPRD Rocketry for first solid rocket

An Eggtimer Quark

As part of the ignition system for our liquid system rocket test, we have started soldering a board that would host a relay which would trigger igniters to ignite the rocket when a signal is received on the relay.

LPRD Rocketry's Glen showing off avionics to be used on the liquid propellant rocket engine test stand

Glen showing off the relay board

Heating element of LPRD Rocketry nichrome wire and cotton ball igniter

Heating element of our igniter

As for our final goals, we are putting together a list of sensors that we would purchase in the next few days. More updates will follow as we get the sensors to work.

Gaurav Manda


Member Spotlight: Jame Moua

LPRD Rocketry's Jame Moua and Flag Football

On the left

Hello, my name is Jame Moua and I am currently a sophomore at the University of Minnesota TC and I plan to double major in Aerospace Engineering and Mathematics with a minor in Astrophysics. I chose to double major because I have a love for both space and math. In addition, I wanted to reconnect with the “younger me,” so I felt that there was a need to include mathematics within my major. I join LPRD Rocketry mainly because I felt like I was not doing much to set myself up for what I was getting myself into, and LPRD Rocketry was an excellent choice which I can see live applications of what I learn in class on work that is hands on or over hearing data collection methods. Moreover, I needed to take more control over in determining where I need and wanted to head in life and “space” was calling out to me.

LPRD Rocketry's Jame Moua's Grad Photo

To move on, I am not in any other school activities due to my work schedule and so I have to take up on the opportunity of going to night classes. When I have free time, I love to play sports, exercise, game, hangout with people, and sitting by myself pondering on life.

LPRD Rocketry's Jame Moua at Science Club

What I want to do for my career is to ultimately become an Astronaut; especially heading into the vastness of space with the advance technology that will come later in the future in hopes of harboring planets (or moons) that has life on it or to even come in contact with extraterrestrial beings (hoping that the situation is not like a Christopher Columbus scenario), thus expanding human knowledge and maybe furthering space exploration. [There are two scary scenarios: We are the only ones in the universe OR We are NOT alone.]

LPRD rocketry's Jame Moua standing next to a pillar dressed all fancy

Jame Moua

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