Rocket flight data

Just to follow up on my last post, I wanted to provide some additional information and the actual flight data, and briefly explain what this all means, especially for all those folks reading this who are not familiar with anything related to rockets or flight computers. And for anyone who has significant experience flying rockets, you may find the below information interesting as well, without any explanation!

As a starting point: a flight computer is basically a very small circuit board that you put inside your rocket, and it has a bunch of neat built-in gadgets to measure exactly how high the rocket went, and how fast, and what interesting events happened when. I’ll explain more below.

This is the relevant flight data for the flight I mentioned in my last post, which went over one mile high:

flight data
flight data

So what does all of this mean?

First of all, it means that the rocket flew to a maximum height of about 7,579 ft – you can see this in “maximum height.” This measurement is made by a barometer taking air pressure readings in the flight computer, starting at ground level on the launch pad, and then many times while it’s in flight. There’s also a GPS chip on this flight computer and you can see it also independently measures the height using GPS, but I’m just going to assume the lower value is more likely correct.

The flight computer also records the maximum speed, which in this case was 904 feet per second (fps), which is equivalent to Mach 0.8, or a little bit slower than the speed of sound.

The total flight time was 145 seconds (just over two minutes), and there’s a further breakdown of how long the rocket spent going up and then coming back down.

The graph is even more intuitive:

graph of flight data
flight data graph

This reflects the same data described above. The black line is the easiest to understand: it represents the rocket’s actual height over time. As is generally the case (unless you experience a catastrophic failure), the rocket zooms off the launch pad extremely rapidly and hits a maximum height early (here, just over 7,500 ft, as you can see from the black units to the left side), and then after parachutes deploy, it descends more slowly.

The red line is speed (extremely high at first and then plummets quickly), and the orange or gold line is acceleration. Both of these units are off to the right side of the graph.

It’s definitely fun to build and fly a rocket, but with modern flight computers and the ability to record all kinds of really precise data, you can really geek out on this stuff. How high can I fly? How fast can my rocket go? Is it descending at the right speed, or do I need a bigger (or smaller) parachute next time? This can really help refine your building and flying skills through a trial and error process, because you have access to reliable data. And needless to say, this can also help you find your rocket if you lose it because it lands really far away out of sight. In that situation, you’ll find the GPS coordinates onboard to be incredibly useful!

NAR Rocket Science Achievement Award

The National Association of Rocketry (“NAR”) has established a “Rocket Science Achievement Award” program, which currently has three categories of awards:

  1. Mile Marker
  2. Faster Than Sound, and
  3. Data Downlink.
rocket launching with cloud of smoke underneath
Darkstar Extreme on Dark Matter “sparky” motor

The awards are pretty straightforward: to achieve Mile Marker, you need to fly a rocket to at least 1 mile (5,280 ft), and you can get additional awards for 2 or 3 miles, or as many as you’d like, in one-mile increments. To achieve Faster Than Sound, you just have to fly a rocket at a speed that is Mach 1.0 or higher. And the Data Downlink award involves real-time telemetry for data beyond just basic altitude and acceleration.

For any of these awards, you have to have documentation of the flight data, including a copy of the data file from a commercial flight computer. If you submit this documentation and it’s accepted, you’ll be awarded a high quality printed certificate and your name will be added to the NAR website, which is pretty cool.

I recently achieved the Mile Marker award when I flew my Darkstar Extreme rocket to 7,579 ft AGL. I plan on even higher flights in the future, of course, and I’d like to try to achieve an award in each of the three categories that NAR established. The data downlink one should be the most interesting and will require a bit of creativity.

In case you’re interested, the award page is here!

Updates: Improbable Ventures is growing!

You may have noticed a few recent changes to the website, and there are more in the works. I just thought I’d take a moment to explain some of the things that I’ve been doing.

First, the website now has a new domain, “improbableventures.org,” instead of the original wordpress domain, “improbableventures.home.blog.” Either one will work and you’ll be directed to the same website, but getting a custom domain was the appropriate next step.

Improbable Ventures with rocket
before

Similarly, we created a banner for the website last year, and it’s gone through several iterations. We’re still playing around with it and are looking forward to unveiling a new logo soon, as well.

rocket passing in front of earth
after

And on that note, you may ask: who is “we”? Improbable Ventures is growing, with two new members of the team. We’ll roll out a more formal announcement with additional info soon, but wanted to give everyone a preview of where Improbable Ventures is headed, and what we’ll be doing in the near future! Our team will be:

  • Posting more YouTube videos to our channel, detailing high power rocket construction;
  • Designing and building a high-altitude two-stage rocket, capable of flying to 100,000 ft;
  • Developing our own flight computer;
  • Machining aluminum parts, and building an all-aluminum rocket;
  • Designing and testing a liquid fuel rocket engine;

And some additional top secret projects to be announced later!

Preview: L3 Fusion rocket build

As mentioned previously, I’m partnering with SBR to build the new L3 Fusion, which you can pre-order now. We decided to film the build from start to finish, in the SBR workshop studio.

the studio within a workshop, recording me building a rocket
behind the scenes

My previous high power rocket builds have been relatively slow. Don’t get me wrong – I generally don’t procrastinate, and once I get excited about a rocket project, I dive in and don’t come up for air until it’s complete.

But my techniques are far from perfectly efficient, and there’s often a substantial amount of long-curing epoxy, and then waiting for it to cure. And then… repeat. Each cure takes hours or even needs to wait overnight, and I’m doubly and triply reinforcing everything to make sure it’s sufficiently strong. Plus I’ve only built a few larger high power rockets so far and I was inevitably much slower in the beginning.

With this L3 Fusion build, however, I was able to move at a much more rapid pace. One big reason was using a fast-curing 12 minute epoxy. You just mix the resin and hardener and get to work. With a 12 minute cure, it’s amazing how quickly you can build!

me building a rocket, in workshop studio
yes, yes… this feels about right

That being said, for purposes of filming every step, this was still a marathon build session. It took a couple days of nonstop construction, even though the steps themselves are pretty simple and there was nothing that I hadn’t done before. At least, in principle. The “marathon” aspect was only because of filming and trying to make the most efficient use of our time.

We did have a few minor technical difficulties. Despite an excellent studio setup with a camera and tripod, external microphone, bright lights, and so on, there were several long stretches where we captured excellent video but the audio was completely missing. This meant we had to go back and figure out what went wrong with the microphone (troubleshooting this was much more difficult than you might think) and then re-shoot some of the steps. This turned out to have a silver lining, though, because the second time through I was substantially less inept than my initial attempts. Still inept, that is, but less so.

me building rocket with parts on workbench
enjoying the build

All in all, this was a really cool project, an awesome rocket build, and a successful video shoot. As soon as we’re done with the editing and have a final product, SBR will share the video on its YouTube channel (and I’ll share it as well, on my channel). In the meantime, if you’re looking to embark on your L3 certification, I highly recommend that you consider this L3 Fusion rocket!

How I decided on my L3 project in high power rocketry

Once I completed my level 2 certification, I had been spending a lot of time thinking about what, exactly, I should build for my level 3 project. And more generally, how should I approach it?

Cardboard or fiberglass?

I’ve built both cardboard and fiberglass rockets, and each has advantages depending on what you’re trying to achieve. I had initially assumed any L3 project would need to be fiberglass, and I’d been looking at some very large and very heavy rockets.

Fiberglass is more durable than cardboard, and is the strongest building material aside from metal. It won’t change size based on fluctuations in temperature, and it won’t swell up or get ruined if wet. This is particularly important since the rocket parts need to slide over each other using couplers. But the primary drawback of fiberglass is that it’s really heavy.

Cardboard (especially when properly reinforced with epoxy) is still durable but more lightweight, and that is a key characteristic when you are trying to defy gravity and launch something into the air. A cardboard rocket will go a lot higher than a fiberglass rocket on the same motor.

While agonizing over this fundamental choice, a solution appeared, from out of nowhere.

Deus ex machina

I had previously met and worked with Scott Binder, the owner of Scott Binder Rocketry (“SBR”), creator of the Fusion Rocket, as well as high power rocket motors and accessories. Scott’s shop is located in Walla Walla, Washington. His flagship rocket is the Fusion, but he’s recently been developing a new, larger version of the Fusion that is specifically for L3 certification – and long story short, I agreed to do some beta testing on this rocket.

white rocket with red and black design
L3 Fusion finished design

In addition to building the rocket and using it for my L3 cert, I am going to create a video tutorial with Scott for the construction of this rocket, from start to finish. I’ll link to that as soon as it’s ready.

L3 Fusion

The L3 Fusion itself is roughly 90 inches in length and a 5.5 inch diameter. With a 75mm motor mount tube, it’s capable of flying an M motor, and I plan to fly it on an Aerotech M1297 for the cert flight. The great part about cardboard is that this rocket only weighs about 22 lbs fully loaded, and it should come close to 10,000 ft. at apogee on the M1297.

L3 Fusion rendering in Open Rocket

The electronics bay will have two RRC3 altimeters, each powered by a 9V battery, and will use omni-directional black powder charges for separation and deployment of the parachutes during flight. The drogue chute is 24 inches and the main chute is 84 in. Descent should be less than 20 feet per second under the main chute.

There are more details forthcoming, but right now I’m excited to dive into this L3 project! I need to begin putting together a comprehensive document describing the rocket, with a lot of technical information. Later, once I begin building, I’ll include a lot of detail about the construction process and materials, with plenty of photos documenting the build step by step. And much later, once it’s complete, the most exciting part: flight!

More to come soon!

Revisiting my 2020 rocketry goals

This has been quite a year. I don’t mean for the world – yes, Australia was on fire, a global pandemic struck and is still ravaging the US, the economy is in free fall, there’s no end in sight, etc. That’s all true. But I mean for me personally. I set some goals back in January for 2020 and I’m crushing them. Like this:

black and white photo of sledgehammer breaking glass
to be fair, it is not that difficult to break through glass

I intended to write this post at the beginning of July, exactly halfway through the year, but things have been busy and time got away from me. I think it’s good to set goals at the beginning of a new year, but it’s just as important to pause a few times to seriously assess progress – or obstacles to progress – and sometimes, to revisit the goals when things change dramatically.

Clearly, a lot changed during this past year. Whatever your goals were at the outset of 2020, the world looked very different on January 1 from how it looks today, in August. Some goals have become literally impossible to achieve, due to external circumstances. Others are still achievable but have become significantly more difficult.

I wrote a post assessing my progress toward my own previously published goals for the year after the first quarter ended, in early April. In short, due to a scarcity of launch opportunities in the winter, and then the COVID-19 pandemic, I wasn’t able to launch anything or get any certifications in high power rocketry (“HPR”). But on the plus side, I transformed my backyard shed into a practical workshop (for rocketry), got a ham radio license so I could use a flight computer in a rocket with telemetry, and did some other cool stuff.

More recently, during the second quarter of the year, I did finally get the chance to fly a few rockets, which was amazing. I got my level 1 and also level 2 certifications in HPR, scoring some nifty badges and checking some major goals off my list. I also got a few additional post-L2 flights for more dual deploy experience.

My original goals for 2020 had also included getting my level 3 certification in HPR, the highest level offered by the National Association of Rocketry (“NAR”). In retrospect, this was pretty ambitious, even in a normal year. I had never launched even a small model rocket before last fall, and in less than a year I was planning to jump (plunge?) into high power stuff, getting multiple certifications.

And L3 in particular is significantly more difficult. True, it’s ultimately just building a larger rocket capable of flying on a more powerful motor (specifically an M, N, or O class motor). But it’s also a much more elaborate process.

NAR has a national L3 Certification Committee; generally two individuals per state are on this committee. You have to contact them and get one to serve as your advisor, and you need to find a second L3 individual as an advisor as well. You have to submit an L3 certification package and application, describing the rocket you intend to build in detail. As you build it, you have to thoroughly document everything you’re doing with plenty of photos and descriptions. Your advisors can question you and can perform on-site inspections of the rocket at any point in time. The rocket itself has to meet certain requirements, such as having fully redundant recovery systems. And of course, once it’s complete, you have to fly it with your advisors present as witnesses, including a successful recovery of the rocket.

That being said, it’s only August, and 2020 is not done yet. Rather, I should say that I’m not done with 2020 yet. I still have goals to achieve, and one of them is my L3 certification. The odds are against me, but I have a plan, and it might yet be possible to do this before the year is up.

Stay tuned for some exciting updates!

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!