Wow! It’s been a while since my last post, so I feel obligated to provide some sort of explanation. It’s been a busy start to the new year. My wife and I had our first baby, Ava, near the end of January, and there was a tremendous amount do in preparation for her winter arrival. And of course there’s been even more to do ever since she joined us nearly four weeks ago! As you might expect, the past month has been a complete blur. We’re a bit overwhelmed but are managing to adapt to life with a newborn. We’re extremely fortunate that everything went well, and we have a happy and healthy baby.
Improbable Ventures is meant to be primarily about rockets, from theoretical rocket science to my practical misadventures in high power rocketry (much more to come on this topic soon). But it is also meant to be broader, encompassing related projects and ventures, and it’s impossible to completely separate it from my own personal life as well – which is why you might see me writing the occasional article about a class I’m taking, or a recent trip or hike I took, or a new baby.
As a sleep-deprived new father, I’m not sure that I have anything particularly profound to say about parenthood that hasn’t been said much more eloquently by other people, many times before. It’s exciting and exhausting. I thought it would be a lot of work, but it turned out to be more than I’d imagined. It’s not particularly complicated; it’s just that virtually nonstop, around the clock care is required.
More interesting than any perspective I can provide is the baby’s point of view. What a dramatic difference to go from being in the womb – totally dark, almost like a sensory deprivation chamber except for hearing mom’s heartbeat and her voice on a regular basis – to suddenly (unwillingly) being born. It must be total sensory overload, except you have no words for anything, no way to describe your experience even within your own mind, and no way to understand anything that’s happening or what might come next. The baby has never had to use her lungs and breathe on her own before, or feel hunger, do things like drink and swallow milk, and suddenly she is forced to figure all of this out – and fast.
While it’s true that babies basically just eat, sleep, and cry (there’s no shortage of crying) all day and all night, it’s remarkable that they learn as rapidly as they do!
A little over one year ago, I came across a question on Quora (an internet forum) about whether it would be legal to build and launch your own rocket into orbit.
I’d always been interested in rockets and space, but I never seriously considered doing this or even realized it was possible, or legal. How realistic is this kind of project? Do you need anyone’s permission, i.e. the FAA? The US government?
One month and an uncountably high number of Google searches later, I was actively exploring the possibilities.
Near the end of 2019 (before we had any idea what kind of year 2020 would be), I set a few rocketry-related goals for myself. I was just realizing that anyone can build and launch real, working model rockets. And they could build and launch big ones, too – high power rockets. I decided to try it out, first building a few smaller low power rockets and sending them up with a small launch pad, and then building my first high power rocket. Somewhat unexpectedly, one of the bigger obstacles I ran into wasn’t the construction of the rockets, but finding a suitable launch site. But I found a few places and had some initial successes. I set some concrete goals going into the new year.
My 2020 goals included the following:
build and successfully launch my first high power rocket;
get my NAR HPR level 1 certification (H or I motor);
get my level 2 certification (J, K, or L motor);
build my first electronics bay, learn more about flight computers, and use dual deploy for parachutes;
get my amateur (“ham”) radio license;
renovate my backyard garden shed and build a practical workshop, primarily for rocket projects;
get my level 3 certification (M, N, or O motor); and
build a two-stage rocket.
Overall, things went pretty well. I didn’t achieve everything on the list, but I did accomplish many of these things and got some high power rocketry experience under my belt – basically everything except the L3 cert and the two stage rocket. And I did actually build my L3 rocket (three separate times!) but had two flight certification attempts that were not successful, so I came close but didn’t quite pull it off. In general, I did a lot of stuff I’d never done before, and learned a tremendous amount along the way.
In short, I had a blast!
The future plans
Turning to 2021, it’s a new year and time to set some new goals. The logical starting point is with the goals I didn’t quite get to finish in 2020. Was I too ambitious? Crazy? Did I just run out of time? Who knows?
Since I already rebuilt my L3 rocket for the third time and it’s ready to fly, my first goal is getting my L3 certification. This will let me fly M, N, and O motors (and there are some even bigger ones beyond that, but first things first). There are no additional certification levels, though, after L3.
Next, I intend to build a two stage rocket. It can be fairly simple and inexpensive – no need to start off with something overly complex right off the bat – but I want to get a solid understanding of staging, and specifically staging using electronics (multiple flight computers). There are a couple important “events” with a two stage rocket, but basically the first stage (booster) ignites on the ground and “boosts” it high into the air, and then the second stage (sustainer) ignites mid-air. The first stage also breaks off and falls back to the ground at this point, reducing total weight and drag so the sustainer can fly much higher on its own. I’ll have much more to say about this two stage project once I dive in.
After that, I’d like to start on a more ambitious two stage project – something made of fiberglass, minimum diameter, and more sophisticated. Ideally I might be able to build a two stage rocket using one M and one N motor that can hit 100,000 ft, but more likely it would be a high altitude rocket that goes a few tens of thousands of feet into the air. I’ll see what’s realistic as I get closer to this goal.
In the meantime, I’m also taking some more math and science classes in 2021. Right now I’m enrolled in a chemistry course as well as a geology course dedicated to dinosaurs. The latter is entirely just for fun and has nothing to do with rocketry, but it isn’t extremely time consuming or demanding either. Chemistry is much more intense, but it’s also much more critical to rocketry, especially if I want to eventually build my own solid fuel motors or get into liquid fuel or something down the road.
On December 9, SpaceX conducted a test of its Starship rocket, and it was spectacular.
The rocket was called SN-8 (which just stands for Serial Number 8), following the naming pattern for each new iteration of the rocket. Elon Musk originally unveiled the idea for the Starship rocket last fall, and the prototypes SN-5 and SN-6 flew about 500 feet before falling back down. This test of a more complete looking Starship went up 12 kilometers, the vehicle’s first high altitude test.
Many people in the rocketry community watched this live. Below is a great condensed/ time lapse video showing both the launch and the landing, in case you missed it:
Basically, SN-8 had a successful launch and flew vertically for 5 minutes, then began falling back to earth. After cutting its engines, it fell horizontally – the “belly flop” maneuver – which maximizes surface area to help slow its descent.
As a side note, there are a lot of principles in rocketry that are the same whether you’re building and flying a very small model rocket or a colossal commercial rocket, and one of them is drag and aerodynamics. Rockets are sleek and meant to minimize drag and air resistance when they’re moving vertically (or in whatever direction they are pointed), but they are really inefficient and have enormous drag if moving at an angle or horizontally. You’d be surprised how slowly even a large, heavy rocket falls back to the ground without any parachute when it’s falling sideways, and often in multiple (connected) separated pieces.
Anyway, back to SN-8: the belly flop was successful in slowing it down somewhat, and then its engines turned back on to turn the rocket again for a vertical landing. Unfortunately, it was still descending a bit too quickly when it hit the launch pad (perfectly on target) and it exploded in a fireball. But overall, this was an unbelievable achievement.
SpaceX is continuing to innovate and make things that were just recently science fiction into a reality.
My own progress in rocketry may be impressive, but it’s not quite at that level yet. I have some catching up to do!
This is a rocketry blog. It’s primarily dedicated to all my misadventures building and flying rockets. I try to document my successes, my failures, and lessons I’ve learned. But I do occasionally venture outside of rockets and try other things.
When math is prologue
For example, last year (2019) I decided to take some math classes at my local community college. There is an explanation for this, and as you might guess, ultimately it goes back to rocketry. I’m not an engineer or scientist, and I didn’t really get a solid education in math and science at the university level. My interests at the time were more in liberal arts – politics and history in particular – and so I ended up with an education in political science and law. I took a few math and science courses, but generally tried to avoid them.
But fast forward a few years, and here I am today building high power rockets. And rockets require a basic understanding of math and science and engineering, at some fundamental level. And it’s interesting, and I enjoy learning. So that’s my story.
I took a placement test last year at the local college and placed into calculus I (the first of a three part series). I ended up taking it, and then successfully completing the entire series over three quarters, each more grueling than the last:
Calc I covered the foundational topics: limits, continuity, derivatives, etc. as well as anti-derivatives and definite integrals.
Calc II covered techniques of integration and their application to definite and indefinite integrals, as well as some differential equations and polar and parametric equations.
Calc III covered a variety of topics including vectors, multivariable functions, partial differentiation, and double and triple integration, as well as series and sequences.
I’m proud to say I got an A in all three of these courses, but it wasn’t easy. In fact, each of them really pushed me to the limit to understand and master a tremendous amount of new (and complicated) material. The studying was intense, and calc III really pushed it to a feverish pitch. But I survived.
There’s something to be said for really expanding your mind and stretching your brain, regardless of the subject matter. I don’t deal with any math in my daily job, and a lot of the concepts in calculus are really fascinating. (If you don’t believe me, you might just need to try a better instructor. Check out Sal Khan’s lessons on Khan Academy, which I used early and often.)
On a related note: did you know that whenever you learn something new, your brain is literally physically re-wiring itself, growing new pathways and connections between neurons? That alone is a great reason to dive into something new and learn.
But I’m off on a tangent (no math pun intended). While 2019 was the year of math for me, 2020 has been the year of the rocket. I’ve documented this elsewhere on the blog, but this past year has been a wild ride: I built and flew my first (and second, and third) high power rockets. I got my level 1 and level 2 certifications in high power rocketry from NAR, and I made two attempts for level 3, which is the pinnacle of high power, at least in terms of formal certifications. (Admittedly both L3 attempts were unsuccessful, but I learned a lot, and I’ll get my L3 eventually.) I got an amateur “ham” radio license so I could use a flight computer with radio telemetry in my rockets, and I retooled the garden shed in the backyard as a rocket workshop. I think I did some other stuff in the past year, too, but I can’t remember everything.
Coding: all the rage
But 2020 doesn’t exclusively revolve around rockets for me. I also resumed my formal education by taking another class: a computer science course on programming, specifically in the Python language.
I decided on this course partly because it seemed interesting – coding is, after all, extremely popular nowadays, with parents enrolling their kids in coding “boot camps” from an early age, and app development seems like a guaranteed lucrative career if not an outright path to billionaire status. But from my perspective, there’s a more practical reason – there are several engineering courses I’d like to take, and some of them require this basic computer science course as a pre-requisite. It’s nothing more complicated than that.
I’m just wrapping up the class this week, and I enjoyed it more than I thought I would. I’m not planning to quit my day job, but there’s a certain element of satisfaction in facing a problem that initially seems baffling or insurmountable, and then gradually solving it. This is just an introductory course and we only learned a few basic techniques, but once you understand them, they can be pretty powerful and can solve a wide variety of problems.
The concepts include things like: input, processing, and output; working with numbers; functions; decision structures (if/elif/else statements to test conditions) and boolean logic; repetition structures (for/while loops); value-returning functions; working with files; and sequences or lists. There’s a nice logical consistency to everything.
Now that fall quarter is ending, I have to decide what (if anything) to do for winter quarter. There are more science courses I would like to take: one is general chemistry – quite important in rocketry – and another is a geology course all about dinosaurs (!). Or I could just throw myself back into building and flying rockets. What do you think?
I finished building the L3 Fusion rocket in early September and was ready to launch – once the wildfire smoke cleared in the PNW – as soon as the opportunity arose. And in late October, I had my chance.
On a frigid Saturday morning, with my wife joining the small crowd gathered at the rocket launch out near Walla Walla, WA, I went through my pre-launch checklist and got the rocket ready for flight. It was mostly ready to go – the black powder charges were prepared and loaded inside the rocket, the M-1297 reloadable motor was already built, the wiring for all the electronics was nearly complete. All I needed to do was plug each flight computer into its respective battery, turn on the GoPro camera, and seal up the rocket with a few rivets. And, of course, install the motor. Easy enough.
I’ve described this rocket before but just to quickly recap, the L3 Fusion is a 5.5″ diameter, nearly 8 ft tall high power rocket specifically designed for level 3 certification. It’s available from SBR at fusionrocket.biz and I highly recommend it. The rocket is cardboard and therefore lightweight (only 11 lbs before adding the M motor, which itself weighs another 11 lbs), but it’s reinforced and double-tubed from top to bottom, and then coated with an epoxy – basically making the rocket incredibly strong despite the light weight. On an M-1297 motor, this thing should fly to 9,000 ft or higher.
The key word, of course, is “should.”
I was a bit nervous, but mostly hopeful and excited. The temperature that morning was brisk – around 30 degrees F – and it didn’t take long for my fingers to get cold and then start to feel numb. It’s particularly difficult when you’re trying to mess with very tiny wires and electronics – think eyeglasses screwdriver (which is literally what I was using to attach wires to flight computers).
But I had built this rocket entirely under the watchful eye of the man who designed it, with his recommendations. We even filmed the entire build as a tutorial for future generations, so this event might go down in history. I can’t say I built the rocket flawlessly, but I was pretty confident the flight would be successful.
As you have probably guessed by now, it was not.
The countdown began: 5… 4… 3… 2… 1…
With a thunderous roar, the rocket shot off the pad and climbed into the sky with lightning speed. An M motor is a pretty powerful one, and so this was expected. What was not expected was just a few seconds into the flight, as we watched it ascend and disappear into the sky, was another loud boom. The smoke behind the rocket, which was otherwise basically a vertical line, suddenly changed as the rocket veered sharply from its trajectory.
It broke up and fell back to the ground in multiple pieces, and the certification attempt was a bust.
We mounted a search with half a dozen people scouring the hilly area where we saw the parts land, and we were able to find and recover everything except for the rocket’s three fins. The fins were completely torn off, but a lot of the rest of the rocket was largely undamaged. We even found the electronics, despite the fact that the e-bay fell separately from the rest of the rocket and it’s quite small and difficult to spot in small bushes and tall grasses on a hill.
You can learn a lot from studying a rocket failure, just by seeing what happened to the airframe. You can sometimes learn even more if you recover the electronics and download the flight data (assuming they’re still working properly), and/or from an onboard camera like a GoPro.
In this case, it seemed obvious that the fins experienced fin flutter, which is a phenomenon where the forces acting on the fins are much higher than they should be under normal flight conditions, and the extreme vibrations can either change the rocket’s trajectory or even destroy the fins.
Leaving aside complicated discussions of aerodynamics, fins are really important to a rocket. The rocket itself is streamlined and has a motor at the bottom which accelerates the rocket upwards (vertically), but anytime the rocket deviates from that vertical path, the fins stabilize it. The air pushing against the broad fins with large surface area pushes the bottom of the rocket back into place. It’s an ingenious system that self-corrects without the need for a sophisticated computerized guidance system. (Very sophisticated and large rockets tend not to have fins precisely because they do have such computerized guidance systems.)
Without fins, the rocket has no stability. In this case, the moment one or more fins were damaged due to flutter, the rocket careened significantly off its straight trajectory. Since it was still traveling at very high speeds just a few seconds into the flight, the forces acting on the rocket were tremendous and it was almost instantly destroyed.
As you can see in the picture above, the entire bottom of the booster section of the airframe was destroyed and all three fins were torn off. Some of the rest of the airframe was damaged, despite the fact that it was double tubed and reinforced with some serious epoxy. And the drogue (smaller) parachute disappeared into oblivion.
But much of the rocket was surprisingly undamaged. The larger parachute never even unraveled and was completely fine, along with both white shock cords connecting everything together. The nose cone and electronics were in great condition as well. Unfortunately both flight computers had their batteries ripped out during this event so they lost power and stopped recording data after the first few seconds, but both are in perfect working order and only needed new batteries, an easy fix.
It also seems clear that the cause of the fin issue was my own flawed construction technique. Typically, with previous rockets, I’ve built the fin can (i.e. the section of the rocket consisting of the motor mount tube and the fins) outside of the larger diameter rocket airframe, and then inserted the fin can into the airframe. This allowed me to use plenty of epoxy attaching the fins to the motor mount tube at the root edge of the fin, and to build up thick epoxy fillets.
In this case, however, I inserted the motor mount tube into the airframe first, and then attached the fins “through the wall” of the airframe tube. I likely didn’t use nearly enough epoxy on the root edge of the fins when inserting them – and because of this, at least one was yanked off during flight when it experienced flutter.
I knew what I had to do. Rebuild the entire rocket (salvaging a few parts from the original if possible, like the parachute and shock cords) and this time, build the fin can outside the airframe and use plenty of epoxy on the fins. Make sure those fins are securely attached and incredibly strong.
Which is exactly what I did, for my level 3 certification attempt #2, just three weeks later.
How did that attempt go, you ask? Well, let me go put on some coffee and I’ll tell you all about it..
I’ve periodically uploaded videos of some of my rocket launches during the past year (with more to come soon, of course). Generally, my YouTube videos don’t get a ton of views. Most of them have maybe 50 or 60 views; some of the more interesting ones have about 600-700. But one video seems to have really taken off – no pun intended.
What’s fascinating to me about this is: why? This is just a twelve second video clip of a rocket launch. It’s the Darkstar Extreme rocket that I built earlier this year, and this particular flight is on a K-535 motor, a common and standard workhorse motor. This video is not very different from several others that I’ve uploaded recently. Yet suddenly and without warning, the views started to dramatically increase: as of when I’m writing this, it’s topped 94,000 views.
As a nice side effect, it’s caused my YouTube channel to gain a bunch of new subscribers. Some sizeable fraction of people who casually see this clip want to subscribe – my total number of subscribers has risen from about 30 to over 170 in the past week or so. This is awesome, from my perspective.
I’m just not sure what accounts for this sudden interest. YouTube provides some analytics and it looks like most traffic (82 percent) is coming from YouTube Shorts, which is something new YouTube rolled out: a vertical video format that’s basically meant to compete with TikTok.
Another 13 percent of viewers are finding this through their suggested videos. Very few people are finding the video by using specific search terms (e.g. rocket launch).
But it’s still mysterious: why this particular video when I have several similar ones? Why now?
If anyone has any suggested explanations, I’d definitely be interested, since I’m still relatively new to this and figuring out how it all works!