Launching rockets in the Oregon desert

Recently, I was able to make the journey out to Brothers, OR to attend my first launch hosted by the Oregon Rocketry Club (“OROC”). From where I live in the Seattle area, this is about a 6.5 hour drive each way, so I stayed overnight in Portland. I’ve done some pretty long day trips, but trying to drive to this launch and back in a single day would just be pushing myself a bit too far.

desert landscape filled with sagebrush
welcome to sagebrush country

I really only spent half a day at the launch, but it was absolutely worth the trip. I was able to launch two rockets – the cardboard HyperLOC 835 that I used for my L1 and L2 cert, and also the fiberglass Darkstar Extreme. This was the maiden flight for the latter rocket and it did not disappoint.

More importantly, this was my first chance to attend a large launch event with a lot of other people (although of course due to COVID-19, attendance was more limited than normal, and attendees were required to follow a variety of safety precautions, including wearing masks and spreading out). I got to witness lots of other flights, which was amazing, and I met some great people.

desert landscape with people standing at a table in foreground
the range at brothers

To summarize the launch site and conditions, it was hot, dry, and dusty. The winds periodically picked up, too, which made the dust more of an issue. But overall, coming from Seattle, I think this was an excellent place to launch.

I flew the HyperLOC 835 here on an I-500 motor just for fun. It was a successful flight, but the wind gusts were pretty high at times. After the parachute deployed, the winds carried the rocket far from the range. I saw where it landed (or so I thought) and began walking in that direction. Once the rocket touches the ground, though, it completely disappears behind the sage, so you have to just hope you’re still walking in the right direction. The longer you walk, the more your confidence begins to waver, and eventually it melts away as the uncertainty increases in direction proportion.

As it turns out, I apparently overshot it and went significantly further than I needed to. I walked for what felt like an eternity, eventually gave up and headed back toward the range – and then fortunately spotted the rocket hiding behind a bush.

red and white rocket in flight
HyperLOC 835

The main event for me, however, was the chance to fly the newly completed Darkstar Extreme, my first fiberglass rocket. This one weighs about 14 lbs and is overall a much more durable rocket. I had some assistance in getting it up on the launch pad.

navy blue and yellow rocket on the launch pad in the desert
Darkstar Extreme on the pad

I have to confess: I was a bit nervous because it was the first flight for this rocket. Sure, I’d built it and done some ground testing at home in my back yard, but was that sufficient? Would everything still work? The really critical components are related to the electronics for dual deployment of the parachutes. If the rocket never separates in the air and the parachutes don’t deploy, then this thing is coming back down like a ballistic missile. Not ideal for the rocket or for all the bystanders.

I was particularly concerned about whether I’d used enough black powder in the e-bay. When it detonated, would it be with enough force to separate the rocket? I’d done some ground testing at home and it separated, but not with the level of force I would like, and I hadn’t had time to do additional testing.

As I feared, the black powder exploded but not with enough force, and it didn’t cause separation. Fortunately, the motor ejection charge detonated as planned and this did cause the rocket to separate, so at least the drogue (smaller) parachute deployed. The heavy rocket came down a bit fast under such a small parachute – roughly 55 feet per second – but this was within a tolerable range and the rocket didn’t sustain any damage whatsoever. I count myself lucky.

navy blue and yellow rocket in flight with cloud of smoke beneath it
the moment of truth

Incidentally, the Darkstar Extreme flew on a K-535 motor and hit about 3,500 ft in altitude.

These launch experiences are a tremendous learning opportunity for me. Each time I attend one, I learn a lot, and in particular from my mistakes. Now I realize firsthand how important it is to properly calculate, measure, and test the correct amount of black powder to use for separation charges – and to test, and test again.

In addition, this experience underscored how critical it is to have a backup plan. After this launch, I decided to go back to the workbench and completely rebuild my e-bay for the Darkstar Extreme. I would add a second (backup) flight computer, along with a second battery and power switch, additional wiring and BP charge holders, and so on. Given the difficulty of locating a rocket after it lands, I also decided to add a sonic beeper just to help reduce to chances of losing a rocket. It would be easy to walk right by your rocket just a few feet away behind some bushes, and never even realize it – but a noise making device would alleviate that problem.

Nobody said that this would be an easy journey, but it’s definitely enjoyable and rewarding. Can’t wait for the next launch!

Top 8 reasons that rocketry is just like Pokemon

I grew up playing the original Pokemon games on Game Boy Color (Pokemon Red, specifically). The animated show was also popular at that time, and I’d watch an episode or two every morning before heading off to school. At the end of every episode was the “Poke Rap,” and I’d sing/ rap along since I knew it by heart. I’ve played many more Pokemon games since the days of Red/Blue (and Yellow), and I’ve seen additional seasons of the show. The characters change, and they keep adding more Pokemon. But I’ll always retain a certain fondness for the original 150.

Years later, I’ve discovered high power rocketry, and I was recently struck by the similarities. Below I’ve compiled a list of why rocketry is similar to Pokemon:

8. Collecting badges.

I recently earned my level 1 and level 2 certifications in high power rocketry (HPR) from the National Association of Rocketry (NAR), and NAR sent me these two badges. Now I can put these badges on the inside of my jacket and proudly display them whenever someone challenges my rocketry credentials – and after you defeat six more gym leaders to collect additional badges, you too can compete in the rocketry league!

close up of metal badges that say level 1 and level 2 certification

7. Expert guidance from Professor Oak.

You’ll find some great mentors – more experienced rocketeers – who can provide advice and wisdom on rocketry. They may or may not be actual professors named after plants (Oak, Ivy, etc.).

6. Friends like Misty and Brock.

You’ll meet lots of people on your journey and make some great friends along the way, even if you have to steal their bicycle or defeat them in battle first.

5. Team Rocket.

Enough said.

4. A frequently “shocking” experience.

With electrical ignition systems that are used to ignite all modern rocket motors, there’s no shortage of electricity themed puns – just like with every Pikachu attack!

pikachu jumping and using electric attack
a real shocker!

3. A superior rival.

Like Ash and Gary, you’ll discover and battle opponents, and there will always seem to be one who is one step ahead of you, at every turn. Unfortunately, you’ll probably never quite catch up.

2. Mom.

No matter how much you’ve been through and how much you’ve grown, there is always the risk that your mom may show up at the launch site, yelling at you to remember to change your underwear, and otherwise generally embarrassing you in front of a large crowd.

1. Bitter failures and setbacks.

There will be plenty of failures, devastation, and general catastrophe in your future, whether you’re battling with Pokemon or launching rockets. But you’ll learn some important life lessons along the way. And, in any event, things will be neatly wrapped up by the time the credits roll!

How to build a fiberglass rocket, part 14: ground testing

The final chapter in the long saga of building the Darkstar Extreme: ground testing.

Actually, I don’t know whether I should have saved this step for the end. I’ve been looking at what some other folks do, and I’ve seen several people conduct ground testing as soon as the rocket is technically built, but prior to any kind of priming or painting, or adding other finishing touches. To be honest, that probably makes more sense because it’s bound to suffer some minor scratches and scrapes during testing, so better to do it “naked” and paint it later. Fortunately, I don’t care!

long blue rocket on wooden test stand, on grass - angled front view
testing time

Just to take a step back and recap what I’m even doing here: ground testing is important to test the electronics inside the rocket and make sure everything is wired up and working properly. I won’t go into the details of the electronics bay, but there are a lot of things connected to other things, and then there are more things. If even a single connection is loose or comes apart, the whole e-bay could cease to perform its basic function.

And by “its basic function,” I mean the flight computer (circuit board), connected to both a battery and an on/off switch, needs to be powered on and fire a charge at the right moment, which causes an electric match to spark, which causes some carefully packed black powder to explode, which causes the rocket to separate in a pre-determined place. And then it all needs to happen again to cause the rocket to separate in a different place. Parachutes deploy, rocket lands safely.

long blue rocket on wooden test stand, on grass - side view
might need a better test stand

Aside from generally checking that the electronics and wiring work correctly, ground testing is particularly important to determine the appropriate amount of black powder (BP) to use. There are different types of BP, and there are many online calculators that will tell you, based on the volume of your rocket’s interior space and your desired pounds per square inch (PSI), how much BP you should use exactly. However, actual conditions can vary, and it’s a good idea to test – and test again.

Ultimately, you want to use enough BP to ensure that the rocket separates, forcefully. Really forcefully. With verve. Anything less than this could cause a failure to separate, which means the parachute probably won’t deploy, which could be catastrophic for the rocket (and potentially any hapless bystanders). Of course, you don’t want to use so much BP that the explosion itself destroys your rocket, either. It’s a fine line. Your precious rocket hangs in the balance.

long blue rocket resting on box, on grass - side view
problem solved

I did multiple rounds of ground testing on different days (note the color variation and also choice of test stands in the different photos). On that note: never use a more elaborate test stand than necessary. Here I was, building a crude stand out of wood, like a sucker! I could have just been using a cardboard box all along. The angle is better anyway.

The calculator told me that I should use about 2.5 grams of BP, but I found that I needed to use closer to 3.0 grams to really separate the rocket forcefully. I also have a backup flight computer with its own separate charges, and for the backup I will use about 4.0 grams of BP. Gotta make sure it gets the job done.

rocket parts spread across grass in back yard, after separation
as god intended

It’s debatable whether this testing is really part of the rocket’s construction, strictly speaking, but in any event this was the final step before launching the rocket out in the field.

Now it’s time to fly!

High Power Rocketry: L2 Certification Flight

Officially level 2 certified!

rocket launching into the blue sky, with fire and smoke below
textbook flight

Fulfilling a 2020 goal

I really started getting into rocketry last fall, less than a year ago, and I had set some goals for 2020 when the year began. My goals included getting level 1 and level 2 certifications in high power rocketry (HPR) through the National Association of Rocketry (NAR).

I think 2020 threw some curveballs at just about everybody, myself included – but after a few false starts and delays, I was able to launch my first high power rocket in central Washington on a beautiful day in June, and as I wrote about previously, I got my L1 cert.

I deliberately chose and constructed a rocket that could be used for both L1 and L2 certification (i.e. it is capable of launching on a more powerful motor), and I built it to be dual deploy capable. I also had plenty of time to study for the written exam, which is required after the L1 certification but prior to the L2 flight. Timing is everything.

Because of this, I was able to do everything in a single day – L1 flight, L2 written exam (which I passed, of course), and L2 flight. I had more than six months to prepare for this day, so it’s not particularly impressive!

white rocket with orange and yellow parachutes lying on ground in green field
a safe landing

L1 vs. L2 flights

On the L1 flight – the maiden voyage – I didn’t want to take any unnecessary risks and decided to keep it as simple as possible, so I didn’t attempt using any electronics or dual deploy. The rocket separated through a simple motor ejection charge.

But for the L2 flight, I wanted to try the flight computer and dual deploy. I was a little nervous because while I checked and rechecked everything in advance, this was still the first actual attempt and there were a lot of firsts: first time using any flight computer or black powder charges, first time arming the electronics on the launch pad, first time using the ground station to communicate via radio with the rocket (using a laptop with the appropriate software and a connected Yagi antenna), etc.

Everything went smoothly, from the launch (see first photo above) to deployment of the drogue parachute at apogee and the main parachute closer to the ground. I recovered the rocket without any damage.

white rocket with text "improbable ventures" lying on ground in green field
mildly improbable

L2 flight data breakdown

What’s particularly cool is the flight computer not only fires multiple pyro charges (and therefore controls the rocket’s separation and deployment of two parachutes), but it also contains an altimeter and other sensors that record the rocket’s maximum height and its descent speed.

For my L2 flight, the rocket reached 3,506 ft, with a maximum speed of 599 ft/sec (Mach 0.5). In other words, the rocket’s max speed was about one-half the speed of sound.

The descent rate under the drogue parachute was 39 ft/sec, and under the main parachute it was 27 ft/sec. The HyperLOC 835 is a fairly lightweight cardboard rocket with a gross liftoff weight (that is, a weight including the motor, parachutes, and everything else inside) of only about 6 lbs, and this descent rate was more than sufficient for a safe landing.

All in all, this was a fantastic experience. A four hour drive each way made this a very long day, but it was absolutely worth making the trip. Inevitably, I also learned a tremendous amount – for example, how to set up a large rocket on the pad and launch rail, how to use the flight computer and ground station software, etc. I also learned what types of things that I could do better next time. Overall, I’m even more excited about future launches – trying out new techniques, flying on even more powerful motors, and capturing data with the flight computer to beat my own previous records!

The life and legacy of Wernher von Braun

I recently finished reading an excellent biography about Wernher von Braun. While browsing a used bookstore in Victoria, BC last year, I picked this book up on a whim. I really didn’t know anything at all about the man or his life, prior to this. In retrospect, I cannot believe I didn’t know anything, and I have to say I’m absolutely floored.

The book is Von Braun: Dreamer of Space, Engineer of War, by Michael J. Neufeld.

black and white photo of von Braun sitting at his desk with model rockets
Werner von Braun, the German-born American rocket engineer, with model rockets

The title really does a great job of summarizing the theme of the book. Von Braun’s life was in many ways a dichotomy between, on the one hand, his lofty intentions, a fascination with rockets and plans to use them for spaceflight and travel to the moon and distant worlds, and on the other hand, the darker side of his achievements, which were the creation of a weapon of immense destruction and war.

Pre-1945: German background and the Nazi regime

Von Braun straddled two worlds in many different ways, both literally and metaphorically. He was born and raised in Germany, received an education as an engineer and became an extremely effective and capable leader in engineering management – that is, leading large, complex engineering projects and organizations involving hundreds or even thousands of people.

As the Nazi regime came to power, von Braun was gradually pulled into its orbit (or intentionally gravitated towards it, depending on your view). He saw that the military and government were a powerful source of funding for the research and development of rockets, and von Braun seized the opportunity.

At Peenemunde, he developed rockets for the Nazi regime, including the infamous V-2, the world’s first long-range guided ballistic missile. The Germans used the V-2 during World War II to attack Allied cities, as retribution for Allied bombings of German cities (thus the German name for the rocket, Vergeltungswaffe 2, meaning “Retribution Weapon 2”). The V-2 was also the first rocket to travel outside the earth’s atmosphere into space. The rocket von Braun brought to fruition was therefore used to bring destruction during the war, but also for pioneering spaceflight, a familiar duality in von Braun’s life.

Von Braun joined the Nazi party and even met Hitler on several occasions. He rose in the party’s ranks and became an SS officer. And yet he never seemed particularly enthusiastic or dedicated to the Nazi ideology or cause. It was clear that his only passion was rocketry, and the Nazi regime was willing to pour vast amounts of money into his organization at Peenemunde. At the same time, he never seems to have strongly objected to what the Nazis were doing, although he likely wasn’t aware of the full horrors of the Holocaust at that time. Years (and decades) after the war ended, von Braun condemned the regime, but of course that was much easier to do in retrospect and seems opportunistic.

black and white photo of three men holding a large model rocket above their heads
William Pickering, James Van Allen and Wernher Von Braun hold a model of Explorer 1 in triumph after the successful launch of a US satellite

Post-1945: Spaceflight program leadership in the United States

After World War II ended in 1945, von Braun emigrated to the United States, one of several dozen scientists brought over as part of “Operation Paperclip.” He settled with his wife in Huntsville, Alabama, and with many other German workers as part of his organization. Von Braun lived in Huntsville for the next twenty years, raising a family there, and working for the US Army. He played a lead role in developing the Redstone rocket, which was used for the first live nuclear ballistic missile tests for the US, as well as the Jupiter-C rocket, which launched the first US satellite, Explorer 1, in 1958 (although this was not the world’s first satellite, which was the USSR’s Sputnik 1, in 1957).

Von Braun may have been opportunistic, but he thoroughly embraced his new American identity and believed that the US should lead the “free world” in the space race against the Soviet Union.

He later joined the newly created NASA in 1960 and played a major role in historic NASA projects, including the Mercury Redstone, Gemini, and Apollo programs. He was dedicated to the success of the Apollo program, and under his leadership, Apollo had a flawless track record for safety and success. The Apollo 11 lunar landing – the achievement of seeing humans actually set foot on the moon in 1969 – was probably the highlight of his life.

black and white photo of von Braun standing in front of enormous rocket engines
von Braun standing in front of the engines of the Saturn V

This is of course only a summary of von Braun’s life, and in this summary I am doing him an enormous disservice. Beyond his engineering, technical, and management genius, von Braun also increasingly became a popular household name as he began appearing in Walt Disney-produced documentaries in the 1950s about the future of spaceflight, and man in space. These documentaries themselves are fascinating, in retrospect, and are the subject of an entire separate post I plan to write.

A controversial legacy

Von Braun was a lifelong spaceflight enthusiast and strongly advocated for putting humans into space and going to the moon. It is safe to say that he is one of the most important individuals of the twentieth century: he basically led the development of the liquid fuel rocket into a mature technology, and he was directly responsible for the success of NASA’s Apollo program, among other accomplishments. And yet his rockets also have the legacy of destruction. He is ultimately responsible for the development of intercontinental ballistic missiles (ICBMs) and the dangerous cloud of nuclear war that hung over the entire world for the latter half of the twentieth century, and continues to hang over us to this day.

Intriguingly, this is a man who was an SS officer in the Nazi party and built weapons for Adolf Hitler, and yet also joined the US government and obtained security clearances, rose in its ranks, and personally met with multiple presidents including Dwight Eisenhower, John F. Kennedy, and Lyndon Johnson.

I highly recommend this book for a thoughtful, balanced study of von Braun’s life in much more fascinating detail.

How to build a fiberglass rocket, part 13: parachutes

Rocket recovery

The recovery system in a high power rocket is extremely important. Needless to say, launching a large rocket extremely high into the air is pretty fun. But that thing is going to come down again, sooner or later, and the recovery system you’ve designed and built for your rocket will determine whether it comes down like a ballistic missile or floats down gently for a soft landing. It could potentially injure or even kill someone. More importantly, your valuable rocket could be completely destroyed.

If the rocket separates in the air, even with no parachute, that’s a good start. A rocket separated into two (connected) parts loses its aerodynamic design; it will fall, but awkwardly and more slowly than if it were in one piece. Of course, if it’s heavy, it’s still going to hit the ground pretty hard.

Drogue vs. main

Better to separate and have a parachute. A single chute can be sufficient – it depends on the rocket’s expected altitude and how heavy it is. Ideally, though, the rocket will be capable of “dual deploy,” which just means deploying two separate parachutes, a drogue and a main.

person running in street, pulling orange parachute behind in the air
a running start

The drogue chute is smaller and deploys at apogee. The idea here is that, at apogee, the rocket’s speed has ground to a halt. It’s no longer shooting upwards, but it hasn’t yet started falling back down very fast either. The rocket separates at this point and the smaller drogue chute deploys, slowing the rocket’s descent to some degree.

After the rocket continues its descent and is closer to the ground, the airframe separates again and the main parachute deploys. This larger chute slows the rocket’s descent considerably and allows for a softer, gentler landing.

This order is important. You wouldn’t want to release the main (larger) parachute at apogee because even a slight wind would carry it very, very far away by the time it landed. But if you only used a drogue chute during the flight, the rocket’s descent would not slow sufficiently and it’d have a rough landing.

person in street, holding open orange parachute above head
I am actually being pulled backwards here

A weighty problem

This brings us to my current predicament. The Darkstar Extreme is a fiberglass rocket, and it’s pretty heavy, at roughly 14 lbs before adding the recovery system or the motor. That’s about what two gallons of milk weigh. Imagine the force it would take to accelerate two gallons of milk vertically, thousands of feet into the air – and likewise, the size parachute you’d need to significantly slow the descent of something that heavy.

There are online calculators that can help determine the right parachute size (diameter) based on the weight of your rocket and how fast (or slow) you want it to land. There are a lot of trade-offs in rocketry, some of which may not be obvious. All else being equal, for example, the softer the landing, the better – but there is a trade-off here. You can slow the descent and get as soft a landing as you’d like by increasing the size of the parachute. But large parachutes take up a lot of space. It’s increasingly difficult to stuff a gigantic parachute into your rocket without increasing the size of the rocket (and its weight, which then requires an even bigger parachute, etc.).

I ended up buying a 2 ft diameter drogue chute and an 8 ft diameter main chute, both from Rocketman Parachutes. In the above pictures, I opened them up as soon as they arrived at my house and ran around in the street trying to catch the wind and fly them like kites – with mild success.

They’re also a very vibrant orange color, which should make the rocket a little easier to see during its descent in the sky, and easier to locate once it touches down.

I’m looking forward to launching the Darkstar Extreme in the near future and seeing these parachutes deploy! I should also be able to capture a lot of data with my flight computer, so I’ll be able to tell how fast the rocket was descending with the drogue, as well as with the main chute.