After a delay of several days due to weather conditions, NASA and SpaceX made history today with a successful launch of the Crew Dragon vehicle atop the Falcon 9 rocket.
The launch took place at 3:23pm eastern time (12:23pm out here on the west coast). The two astronauts aboard the vehicle, Bob Behnken and Doug Hurley, are now well on their 19 hour journey to dock with the International Space Station, where another US astronaut and two Russian cosmonauts await their arrival.
This is a historic mission – the first time the US government is launching a manned rocket from US soil since the final Space Shuttle flight in 2011. It’s part of a new public-private partnership called the Commercial Crew program, a joint effort between NASA and SpaceX.
On top of this, after the Falcon 9 detached from the Dragon vehicle, the rocket had a successful vertical landing back on earth.
UPDATE: As you probably already know, today’s launch was postponed due to weather conditions. The launch is rescheduled for Saturday, May 30. Fingers crossed for good weather this weekend!
I generally only post about my own rocket-related adventures, but I would be remiss if I didn’t acknowledge that today is a historic day for space and rocket launches.
NASA and SpaceX have partnered in the Commercial Crew Program to launch astronauts to the International Space Station (ISS) on a US spacecraft from US soil for the first time in 9 years, since the final Space Shuttle launch in 2011. NASA astronauts Robert Behnken and Douglas Hurley will fly on the SpaceX Crew Dragon vehicle, lifting off on a Falcon 9 rocket today at 4:33pm eastern (1:33pm pacific).
This is exciting, amazing, and historic! You can watch the launch live through NASA’s website here:
Like many fiberglass rocket kits, the Darkstar Extreme has an aluminum-tipped nose cone. The aluminum tip is for more than just show: it has a couple of structural purposes.
One is the manufacturing method of the nose cone itself. The process uses “filament wound fiberglass,” which involves placing resin-impregnated fibers around a mandrel (a gently tapered cylinder). It is difficult to make this come to a point, and instead the manufacturer just shortens the nose cone and puts an aluminum tip on.
Another purpose is that during flight, the tip of the nose cone absorbs the most heat, and aluminum is a better material to use for this specific part of the rocket.
So, the question for me now is: how to connect the nose cone to the rest of the airframe?
You might be asking: how hard can that be? And you’d be right; it isn’t particularly difficult. But some nose cones have a portion that can fit inside the rocket body, as though there’s a built-in coupler. This nose cone, though, is the same diameter as the rocket body and will not fit inside it.
The good news is, the rocket comes with a 6 inch long coupler. Half goes inside the nose cone, half inside the airframe (payload section). On the nose cone side, I just epoxied them together to create a permanent bond. On the other side, I drilled three small holes through the airframe (and coupler) and inserted nylon screws (shear pins). This allows everything to stay together until a large force is applied mid-flight and the airframe separates from the nose cone, deploying a parachute.
The bad news, however, is that I need to attach a kevlar cord to the nose cone somehow, and the best way to do this is to put a bulk plate with a forged eye bolt on one side of the coupler. Either side will do, but it makes sense to put it on the side that goes a few inches into the nose cone, rather than the side that comes a few inches out, since that increases the available storage space inside the rocket for things like the parachute and 25 feet of kevlar cord.
The kit came with a fiberglass bulk plate with no edge or lip (see above picture). It will fit inside the coupler, but I don’t feel too confident that epoxy alone will hold it in place. Instead, I ordered another aluminum bulk plate with an edge or lip – the inner part fits inside the coupler, but there is an outer lip that sits above the coupler so it cannot be pulled through, no matter how hard the cord is yanked.
I epoxied the aluminum bulk plate to the coupler, and then used more epoxy to attach the forged eye bolt (with a long screw attached) and two nuts to the bulk plate itself. There’s no way this setup is coming loose during flight regardless of the forced applied.
Above is a view of the inside of the coupler. I added some masking tape in an attempt to create a very crude barrier or dam, keeping the additional epoxy a bit closer to the edges to seal them.
That’s it! The coupler and nose cone are in good shape, and I’m ready to move on to the next section: my old friend, the e-bay.
With the airframe of the rocket nearly complete, I just needed to prep the area where fins will eventually go. The rocket is pre-slotted (i.e., it comes with slots already punched out to insert the edge of the fins), but the slots are all too narrow and needed to be sanded quite a bit to widen them.
In addition, I drilled 12 individual holes (one for each side of all 6 fins). Later in this assembly, I’m going to insert the fins into these slots, where their edges will be up against the motor mount tube inside this airframe. I’ll then inject epoxy with a syringe into each hole, and tilt the rocket back and forth to spread it around, ensuring that the fins are strongly secured in place both internally and externally. But I’m getting ahead of myself.
On to the motor mount tube!
This 75mm fiberglass tube has a slightly smaller diameter than the 4″ rocket airframe. (To be clear, I have no idea why the motor mount tubes are almost universally measured in metric units – 54mm, 75mm, and 98 mm being fairly common in high power rocketry – while the airframe itself is measured in inches. It’s a mystery for the ages.)
There are 4 beige colored fiberglass centering rings: the inner diameter of each ring fits snugly around the motor mount, and the outer diameter of each ring fits inside the larger airframe. The purpose of these rings, as the name implies, is to center the motor mount inside the airframe.
The primary goal here is to secure the yellow kevlar recovery harness to the motor mount. Later, I’ll attach a much longer kevlar cord to this one, and the other end of that cord will attach to one end of the e-bay (with a parachute attached as well).
This basically makes sure that the bottom part of the rocket, including the motor, stays linked to the e-bay in the middle of the rocket – and also makes sure that a parachute can deploy, when these parts separate after apogee. Since there’s nothing obvious to hook or attach this cord to on the motor mount, the solution is to simply epoxy it directly to the motor mount.
I measured the width of the cord (1 inch) and marked it on the top centering ring, and then sanded down a 1 inch width on both sides of the inner part of the ring, to allow just enough space for the cord to fit between the ring and the fiberglass tube. About 6 inches of cord are on each side of the tube.
After that, I created some very crude “dams” with masking tape since the epoxy is a bit runny before it cures. I put a generous amount of epoxy underneath the cord to bond it to the tube, and then even more on top of the cord, in order to totally encapsulate it.
Here you can see a “before” and “after” picture. I couldn’t quite get all the masking tape off afterwards because some was sealed and bonded (somehow I did not foresee this). But the cord is totally encapsulated. When the epoxy cures, it becomes incredibly hard and is similar to plastic.
The recovery harness here is now thoroughly secured to the motor mount.
A few notes on epoxy, as this was my first time ever using it. It’s pretty straightforward, but there’s a slight learning curve. I used West System 105 resin and 205 hardener: these are two separate products that come in separate containers with pumps. You add them together (in a ratio of one pump each) into a mixing cup, and then mix them together (I used a popsicle stick) very thoroughly, for several minutes.
Once mixed, the epoxy begins to harden and cure much faster than I initially realized. It also gets very hot, from the chemical reaction – to the point where it’s literally giving off visible steam, and the heat from touching the outside of the plastic mixing cup will burn your fingers.
It’s also a bit runny when spreading, so it really helps to create a barrier or dam with masking tape to keep the epoxy where you want it, as it cures. The tape can easily be removed later.
I was previously used to working with wood glue for cardboard rocket sections and plywood fins, but fiberglass is a whole new experience. Wherever fiberglass pieces need to be permanently attached (e.g., the fins to the rocket body), this two-part epoxy is used, and it’s amazingly strong.
My first couple of posts related to the Darkstar Extreme were just recapping my progress in high power rocketry to date, and outlining everything that’s needed in order to build this particular rocket. But now I’m finally ready to begin assembly.
As mentioned previously, the “kit” basically includes all of the rocket airframe parts (shown below), along with some nylon recovery harnesses and miscellaneous hardware (steel screws, nuts, washers, forged eye bolts, and quick links). The first thing I did after unboxing everything was soak the fiberglass pieces in water for 24 hours, to remove any remaining mold release agent. In other words, as the proud parent of a new rocket, one of the first things you should do is to give it a proper bath.
After rinsing off and drying each piece, I moved everything out to the workshop. Time to begin construction of the workshop’s inaugural rocket.
Just to provide some overall structure for what I’m planning to do here: the idea is to assemble the fiberglass airframe, but in a way that allows it to separate at multiple key points in the future. In certain places I’ll use epoxy to permanently attach pieces together, but in several other locations I’ll need to measure and drill holes, and then insert small nylon screws (“shear pins”) which are strong enough to hold the pieces of the airframe together, but which also have the ability to shear in half when sufficient force is applied (e.g. a small controlled explosion), allowing the rocket to separate and a parachute to deploy.
To help visualize how all these pieces go together, the major components of this airframe (from top to bottom, when the rocket is standing vertically on the launch pad) are: the nosecone (grey, with aluminum tip) permanently epoxied to a 6″ coupler; a 24″ payload section; an 11″ coupler which serves as an electronics bay; and a 52″ booster section. There is also a 1.5″ band or ring that fits around the e-bay/ coupler, and six fins (three larger, three smaller). Inside the booster section is a motor mount with a smaller 75mm diameter and 4 centering rings.
Here you can see a lot of measuring, marking, and drilling on the airframe. More specifically, there are 3 holes drilled in the nosecone/ coupler and the payload section, which can then be secured together (and later separated) with shear pins. Another 3 holes and shear pins connect the “bottom” of the e-bay/ coupler to the long booster section. And then three more holes – this time plugged with steel screws serving as rivets – connect the “top” of the e-bay/ coupler to the payload section. These steel rivets ensure the payload section does not separate from the e-bay during flight, but they allow diassembly on the ground by removing the rivets, if needed.
Finally, in the middle 1.5″ of the e-bay/ coupler, I marked the location of the band or ring that will be secured to the coupler with epoxy, shortly after this.
Aside from measuring, labeling, and drilling, I also needed to sand many parts of the fiberglass airframe. In general, it’s helpful to sand anywhere that epoxy will be used to ensure better bonding. This includes a few external areas (like the one pictured above), as well as the areas on the centering rings where they will touch the motor mount and the booster section; the edges of all six fins, along with the areas that the fins will touch on both the motor mount and booster section, and so on. Lots of sanding here with coarse (60 grit) sandpaper.
So begins the thrilling assembly of the Darkstar Extreme.
I provided a full list of materials that I’ll be using to build the Darkstar Extreme, but just to offer a little preview on what the completed rocket will look like, here are some of the specs. And the picture below is just an example of the finished version – to be clear, I don’t usually post pictures that aren’t my own, but my rocket will look similar to this once it’s done (just probably a different paint job).
Length: 101 in. (about 8.5 ft)
Dry weight: 223 oz (about 14 lbs)
Airframe diameter: 4 in.
Motor mount diameter: 75mm
Altimeter/ flight computer: TeleMetrum
Backup altimeter: TBD
Main parachute: 8 ft diameter Rocketman parachute
Drogue parachute: 2 ft diameter Rocketman parachute
I’ve already started construction, so I’ll have a lot more updates coming soon.
As promised, below is the full bill of materials that I’m using to build the Darkstar Extreme. It’s important to note that, aside from this particular kit, many of the other things in this list are optional, depending on your particular rocket design; frequently, parts or materials can be swapped out and replaced with other similar items.
Darkstar Extreme kit from Wildman Rocketry, including:
Fiberglass booster (52″ length, 4″ diameter)
Fiberglass payload (24″ length, 4″ diameter)
Fiberglass coupler (11″ length, 4″ diameter)
Fiberglass coupler (6″ length, 4″ diameter)
Fiberglass nose cone (4″ diameter) with aluminum tip
Fiberglass motor mount (75mm diameter)
Fiberglass vent band (1.5″ length, 4″ diameter)
Fiberglass centering rings (x4)
Plywood centering rings (x2)
Fiberglass fins (3/16″ thick)
Aluminum bulk plates (stepped, CNC cut) for e-bay and nose cone
With the workshop newly completed, and a seemingly endless quarantine/ lockdown in effect, it’s time to turn my attention to building a new rocket.
So far, I’ve built and flown a couple of low and mid power rockets, and I built one high power rocket – the HyperLOC 835, which is a 4″ diameter rocket made primarily from thick cardboard and plywood, with a 54mm motor mount. It can fly on an H, I, or J motor, and I plan to use it once launch events start up again for my L1 certification and probably for my L2 cert as well. It also gave me the opportunity to build my first electronics bay and learn more about flight computers and telemetry.
My next project is a bigger high power rocket: the Darkstar Extreme. This one also has a 4″ diameter but it’s made entirely from fiberglass (except for the aluminum-tipped nosecone and aluminum bulk plates). Fiberglass is significantly stronger than cardboard, wood, or other similar materials; it’s the strongest building material for rockets aside from aluminum.
The other chief advantage of this rocket is a larger 75mm motor mount. More powerful motors come in larger diameters, and this rocket can technically fly on a K, L, or even M motor. An M motor would require me to get my L3 certification, a daunting goal, though one that I plan to achieve in the not too distant future. But I could fly it on a K or L motor as soon as I get my L2 cert.
After unboxing this kit and soaking the airframe pieces in water for 24 hours, I’ve laid out the pieces on my workbench and am ready to start construction. The kit only comes with the major pieces: the fiberglass airframe and nosecone, a few aluminum bulkplates, some basic hardware (forged eye bolts, nuts, washers, and quick links), and nylon recovery harnesses.
The kit does not include the motor (of course), any parachutes, fire blankets, a motor retainer, or certain other necessary hardware (nylon screws/ shear pins, steel screws/ rivets, additional metal bulk plates, etc), so I bought those separately. I also splurged on some kevlar recovery harnesses rather than using the nylon ones that came with the kit because kevlar can withstand significantly higher temperatures and won’t burn easily.
I’ll post a more comprehensive bill of materials separately in case anyone is interested.
With that work complete, it just left cleaning up and furnishing the inside to create a true workshop.
Most of this work was mundane – sweeping up a cartoon-like cloud of dust around myself, using a shop vac to get up sawdust and debris, etc. I also set up a second workbench against the back wall, and a few houseplants just to lend some color to the shop. They get plenty of direct sunlight during the day through that window.
I installed a few shelves (see below) to hold bags and cases of tools and equipment, and got some circular holders to tidy up the multiple 100 ft extension cords. The fire extinguishers were already in the shed, but I decided to keep them around in case something catches on fire (extremely likely).
I also put up a second light fixture overhead (not pictured here), installed some additional pegboard for hanging tools, and a few other miscellaneous things.
The primary reason I needed a workshop to begin with was just for more space – some workbench or table area to lay out parts, and measure, drill, cut, sand, glue, and generally build things. With that goal in mind, I can say: mission accomplished.
Finally! Just a place to sit and assemble rockets. It’s only about 10×10 ft, but it’s a really practical space.
I may spruce up the inside or outside of this shop more over time, like adding some flooring, building a larger exterior deck/ porch, and so on. I have a few other ideas. But the core goal is complete, and I’ve already begun work on my next rocket, the Darkstar Extreme from Wildman Rocketry. Much more to come on that soon!