mechanical Archives - Castle Point Rocketry

News

Testing Review

July 18, 2019June 5, 2020
by Dakota

[This is a long article, but it has some very important updates.]

Over the last ten days, Castle Point Rocketry tested our proof-of-concept rocket. We traveled from HQ in Hoboken to our test site in southern New Jersey on July 9th and returned on the 18th.

Here’s what you need to know.

Setup

The preliminary phases of our testing schedule took longer than anticipated. Though this was the team’s third visit to the site, more infrastructure needed to be laid out. We ordered chemicals, installed the truss, and established ground control. We spent Wednesday through Saturday making sure everything was perfect.

Tank Testing

As mentioned in Ready to Test, validating the liquid oxygen (LOX) tank was the first step of our testing procedure. Infinite Composites Technologies manufactured our LOX tank, and they asked that we do preliminary tests for them.

On Sunday, July 14, an advisor approved us to start testing.

Time lapse footage of our LOX tank going up.

TT.01: COPV Cryogen Validation

Composite overwrapped pressure vessels (COPV) such as our LOX tank have been proven capable of withstanding high pressures. COPVs provide a burgeoning market for lightweight tanks by eliminating the need of an internal metal liner. The manufacturer expected that their formula would withstand low temperatures, too. But putting both together… That was our job.

After retreating 100 meters to Ground Control, we opened valves in a unique sequence to begin the test. First, cryogenic liquid nitrogen (LN2) filled the tank 4/5 full. Then we squeezed pressurized gaseous nitrogen (GN2) into the space that remained, elevating the tank pressure to 500 psi. (Air pressure at sea level is ~15 psi.)

From our perch in Ground Control, we couldn’t see exactly what was happening. But we had an array of sensors and cameras on-site that processed live data back to us.

The team watches the LOX tank closely… from afar.

The LN2 in the tank caused a thin layer of water to condense — and then freeze — on the tank. This temporarily turned the tank from black to a cloudy white, then back to black when the ice melted.

After holding for several minutes with no drop in pressure, the team agreed there were no leaks present. Ben actuated the dump valve, releasing the remaining LN2 in a plume of white steam, and we approached the tank to inspect the tank. No cracks, vents, peeling, or patching were found. We concluded that the Infinite tank could withstand cryogenic temperatures at high pressures.

TT.02: COPV LOX Compatibility Validation

TT.01 took less time than expected. On the order of hours. We planned the day with 4 hours for each test, yet TT.01 only took 34 minutes from start to finish. Too easy. Upon consensus from Nathan (Team Lead), Monica (Safety Officer), and Luke (Industry Advisor), we moved swiftly into TT.02.

Following TT.01, there wasn’t much to do in terms of preparing for the next test. After all, we simply needed to swap out an LN2 cylinder (called a dewar) for a LOX dewar. This required new hoses, too, but we came prepared. Within 30 minutes, we were back at Ground Control.

A screenshot from the program recording our incoming camera feeds. CCW from top: Infrared thermal imaging, test site visual, and dump valve close-up.

We took our time with this test. Though LOX boils at a slightly higher temperature than LN2 (-297°F instead of -320°F), it is much more dangerous. When LN2 boils off, it creates GN2. GN2 makes up 70% of the air we breathe — it is stable, is non-reactive, and plays well with others. LOX, however, boils off into gaseous oxygen (GOX). GOX is incredibly reactive, as oxygen is the driving force of any combustion reaction. With the slightest disturbance, a thimbleful of LOX can create a dazzling explosion. Should either GOX or LOX chemically react with the experimental COPV, a hole would release all oxygen at once, providing the basis for a massive fireball.

Luckily, we did not deal with any such eruption. Though the tank off-gassed a lot more than expected, much more than the LN2 run, we rang in yet another success. A holding time of 10 minutes proved our tank held an adequate amount of LOX to launch with.

TT.03: COPV Pressurize LOX Validation

Though we took our sweet time to make sure all of the GOX had adequately diffused before we drove the van up, we still had a remarkable amount of time left in the day. “Why not do another test?” we thought.

This test required LOX again. Under pressure, this time. We took a collective breath and pushed “Start.”

Once again, we were surprised by the amount of gas released from the system, but we assured ourselves it was nothing to worry about. The pressure did stay constant at ~300 psi for the full test, which indicated we didn’t have a leak.

Full Stack Testing

Following our three successful Tank Tests, we went into overhaul mode. Full Stack Testing required removing the LOX tank from the gantry hoist, placing it back in the rocket, and raising the rocket on the truss. Additionally, we needed to move our ground support relay boxes and fire extinguishers. (These relay boxes are like runners in a relay race. They act as a hand-off of information between Ground Control and the valves and sensors.) This change took the team a full day to complete.

FST.01: Full Stack Pressurization Test

Now comes the part of our story that gets a little bit… sad. On Tuesday, July 16th, we launched into FST.01 with great expectations. But the pressure just wouldn’t build. FST.01 only required the use of GN2. Since GN2 is practically harmless, Luke approved us to stay on-site with the rocket until we reached a pressure of 100psi. But even with our gas cylinders all the way open, we simply couldn’t get above 25psi.

Monica, Will, and Luke descended upon the LOX tank, assuming it (or one of its fittings) was the culprit. After a lengthy, methodical search, they found the problem: A hairline crack had formed on the very bottom of the tank. This was a deal-breaker.

Here’s the deal with cracks: They aren’t good for structural stability. Even at pressures as low as 25 psi, the crack was undoubtedly growing. Undetectably slowly, maybe, but definitely growing as GN2 tried to force its way from high to low pressure. Had we increased the system pressure any more, this effect would have increased dramatically — ending in a catastrophic burst as all of the GN2 left at once.

A tank exploding onboard the rocket was not what we wanted — so we unfortunately had to call off the rest of our testing schedule.

Moving Forward

So, what happens now?

After careful consideration of the data, the team concluded that the hairline fracture had occurred from “temperature cycling” the COPV. The tank went through a series of contractions and expansions as it got subcooled then superheated, which delaminated the layers of the COPV. In much the same way that ruffling a phone book puffs it up, this had introduced space between the “pages” of the tank wall, eventually leading to a full crack.

So, Castle Point Rocketry is still in our Testing Phase. Though we weren’t able to get through all five Full Stack Tests this week, we will soon have another tank. In the meantime, though, it was nice enough just to raise a rocket in the air — depressurized, of course — and look at what we had built.

For ease of access to the internal components, we didn’t add the nose cone, fuselage (skin), or fins. In a launch scenario, the rocket would look different.

News

Testing: Days 0 – 2

July 12, 2019June 5, 2020
by Dakota

These last three days were dominated by the minutiae associated with launching a rocket. Sure, we did as much setup as possible beforehand. But there’s much more to do once the rocket actually gets here.

Day Zero: Packing Up

Tuesday, July 9, was particularly chaotic. Myriad administrative snafus demanded quick action from the whole team. Dakota grabbed a truck so we could transport our rocket. And, most pressingly, we needed to move everything out of our Griffith work space and go mobile.

Monica, Nathan, Ben, Dan, Will, and Dakota (behind camera) take a breather after lifting our rocket onto the dolly. More straps and plastic wrap were added to further reduce movement.

Due to everything else going on, we didn’t even get around to packing until 6:00pm. By that point, we knew we would be leaving late, but we hoped 1:00am would be the limit. Yet 1:00am came and went.

At 2:30am, we gently loaded the rocket into the truck. (Lift gates are a blessing.) It took all of the remaining six of us, but it happened without a snag. Come 4:00am, we were practically finished.

Our lab and rocket, all crammed into one 26′ box truck.

The lab looked lived in, but at least it was devoid of much our mess. And what better time than 4:00am to start 2.5 hours of highway truck driving?

Day One: Tying It All Together

Dakota scrambled into the driver’s seat. Ben and Rodrigo piled in and kept him company to Salem County. (And kept him awake.) After all, there’s that old saying: “Six eyes are better than two with a $500,000 rocket and boxed-up laboratory in tow.”

They arrived okay — and just in time to volley off the first round of calls to gas/cryogenic companies to confirm our delivery schedule. Starting at 8:00am on the dot, Dakota, Will, and Nathan were on the phone until noon. Then, it was just a matter of waiting for the team to assemble.

The shed at left will store our chemicals. Ground control is barely off-screen to the right. The test site is 2,000 feet behind the camera.

A brief team meeting preceded driving to the test site and setting up ground control. The remaining daylight hours were swallowed up by running 2,000 feet of fiber optic cable and cleaning out the on-site shed for our chemical deliveries.

Day Two: Finishing Touches

It took a little under 14 months, but it’s finally happened — Castle Point Rocketry has received a shipment of rocket propellant. (The oxidizing half, at least.) Shortly after a late start to the day, the first cryogen delivery came through: liquid nitrogen and liquid oxygen. It’s a good thing we got that shed cleaned out!

For the rest of the day, we split up into small project teams. The test stand was bent and needed a quick weld — Rodrigo made short work of it. Over the weekend, the gantry hoist slipped on the muddy ground. We righted and reinforced it. Ben and Nathan focused on getting the avionics and valves attached and laid out.

CP Rocketry Test Site, featuring the Mayor’s Soy Beans

Though all parts of plumbing were screwed together, Will and Monica still had some tightening to do. They spent most of the day in the truck-lab working on the rocket. Dakota manned the ground control station, where there is WiFi and a view of the road, to finish up some remaining purchases and administrative duties.

The inside of our truck-turned-lab. (There are no chemicals stored inside.)

When interrupted by a small storm, we broke for lunch. Then, after three more hours in the sun, a massive thunderstorm rumbled in from Delaware. We took it as our cue to leave before it got dark out — but not without first getting absolutely drenched.

What’s Left

We’re zooming in on the first day of true testing. It’s highly likely that, after a delivery Friday morning, we will be testing Friday afternoon. In the meantime, the team still has a short laundry list of tasks to accomplish. First and foremost, we need to reestablish ground control. It kinda tipped over in the rain, and we had to rescue it.

Stay tuned to our Facebook page for a live feed of testing. (Or the live feed itself.)

News

Ready to Test

July 9, 2019June 5, 2020
by Dakota

Here we go. The last fourteen months of work have all come down to this: testing. Over the last two weeks, we have traveled back and forth from South Jersey to inspect the site, set up infrastructure, and clear the area.

In the next 6 days, Castle Point Rocketry will be pursuing a rigorous testing schedule. The testing procedure is 65 pages… But what all will we be doing?

You’ll be able to follow along on live streams that we post to our social media pages. In case you’re still curious what we’re doing along the way, here’s a short explanation.

Phase One: Tank Testing

The first set of tests caters specifically to our experimental liquid oxygen (LOX) tank from Infinite Composites Technologies. Though the composite overwrapped pressure vessel (COPV) is theoretically capable of handing pure oxygen at such cold temperatures and high pressure, we want to test it to be absolutely positive. That way, if we notice any problems, we can stop everything before we have it inside our rocket.

Our Tank Testing series consists of three tests. TT.01: COPV Cryogen Validation proves the tank can withstand cryogens at high pressure. (A gas is “cryogenic” if it can be turned into a liquid below -240°F .) Then, TT.02: COPV LOX Compatibility Validation and TT.03: COPV Cryogenic Pressure Validation step into chemical compatibility with LOX and a system at full pressure.

Phase Two: Full Stack Testing

The second set of tests is more complicated and involves more subsystems. Rather than just the LOX tank and its assorted plumbing, the next five tests incorporate the whole rocket — but don’t let it leave the ground. Computer, mechanical, and chemical systems all interact with one another to give the team an idea of the rocket’s performance.

Similar to the Tank Testing procedures, FST.01: Full Stack Pressurization Test and FST.02: Cold Flow Test simply ensure that everything can withstand operational temperature and pressure. Then, we introduce fire.

FST.03: Ignition Sequence Test is expected to be the longest test Castle Point Rocketry will perform. It is a critical juncture of the project, for limiting the time between when chemicals flow and when the engine ignites will conserve precious fuel and help us make it to the Karman Line. FST.04: Hot Abort Sequence Test then double-checks that, once turned on, we can turn it off as necessary.

Finally, the grand finale. FST.05: Full Stack Hot Fire Test. This test will be the most exciting, the most relieving, and the most Instagram-able. (So we’ve left room for it to happen twice.) Picture a rocket — without its nose or tail — strapped to the ground, straining upwards under full thrust. This test is essential not only to prove we can launch, but also to fully grasp the efficiency of our engine.

What Then?

And then, well, we pack up and go home. We’ll have a truck to return, a rocket to clean, and some data to send off to interested parties. Not to mention, we’ll be so ecstatic we probably won’t sleep for three days. (Or, alternatively, so ecstatic we will sleep for three days.) We have the future of this project to look forward to — including a launch looming in the near future.

News

“Always Open”

June 24, 2019June 5, 2020
by Dakota

Those of you who follow us on Facebook may have noticed a quirk. Under the “About” section, just under the map of Hoboken, it says “Always Open.” This is no mistake.

Here’s a little peek into what we’ve been up to this weekend — at all hours of the day.

Tank Cleaning

As you may recall from a few weeks back, the vast majority of our propulsion system needs to be “Clean for Oxygen Use.” We have finished pipes, fittings, and adapters and are onto the bigger pieces: our tanks.

The helium and oxygen tanks we use were made special for us by Infinite Composites Technologies. We are rigorously cleaning both with isopropyl alcohol baths to dislodge any remaining construction materials from the inside.

Since the alcohol coming out is dirty, we also needed to clean it for reuse — about 34 liters (9 gallons) worth. Monica and Dakota spent much of Saturday vacuum filtering all 34 liters.

The process of vacuum filtration. Dirty isopropyl in the top, clean out the bottom.
We changed filters once every 2 liters — about when they started to look like this.

Load Cell Calibration

A by-product of last weekend’s Dry Run Mechanical Test, we are confirming all of our load cells work. In order to accurately measure the thrust of the rocket, we will attach it to the ground with cables. These cables will pull on our load cells, which tell us how much thrust the rocket has.

Ben was hard at work making sure the code was solid while Will used the engine hoist to test a few known loads.

Will’s load cell testing apparatus.
Ben working on code — as seen through the clean room walls.

Now that it’s Monday, Will, Tom, and Abe are out on Walker Lawn with the load cells and duck bill anchors. The anchors are being used to test the load cells, and vice versa. We want to make sure our duck bill anchors are rated properly. After all, the last thing we would want is for an anchor to come out of the ground during a test.

Fitting Tightening

Last but not least, we have our piping. As mentioned above, all of the propulsion subassemblies have been cleaned for oxygen use. Now, it’s just a matter of preparing them for testing and launch.

Our propulsion system has threaded joints from two rival piping standards: JIC (Joint Industry Council) and NPT (National Pipe Tapered). Each of these two standards comes in multiple sizes — and each size requires a unique tightening force. Larger threads require greater tightening force — as much as 100 foot-pounds.

Nathan and Will using two wrenches and a vise to tighten a JIC-12 fitting to specification.

In order to accurately tighten each joint, we use both a torque wrench and a crescent wrench. (One to twist, one to hold the rest of the subassembly.) For some subassemblies, more advanced methods are needed, though. In the case of particularly wiggly or oddly-shaped pieces, a vise is necessary to get a good grip. Thus the above picture outside the clean room — as long as the interior is not compromised, the outside of the subassembly can always be cleaned again.

A Little Fun

We also manage to have a little fun after a long day’s work. (And usually right before another long night’s work.) Friday night, we all stepped outside to enjoy a barbecue dinner. Because how else would we ring in the first day of summer?

News

Dry Run Testing

June 19, 2019June 5, 2020
by Dakota

[This is a long article. If you’d like to see just pictures and videos of our tests, check out our YouTube and Facebook pages!]

Last week, Castle Point Rocketry had two full days of testing. We verified our mechanical and avionics systems to ensure full preparation for the next round of testing: propulsion. In propulsion testing, we will light the rocket and measure the thrust it produces. It was necessary, then, that we check to make sure the test apparatus works (and can support the weight of the rocket) beforehand.

At the end of the second day, we had a fake rocket towering into the night sky.

It took all of both days, but the test was a success. We strapped a 500-pound surrogate rocket to the test stand and raised it from horizontal to vertical. In the dark!

Day One: Wednesday

We started the day by needing a U-Haul. Our lab in Griffith isn’t too far from Walker Lawn, where we were testing, but hauling a literal ton of metal up the hill sounded … none too fun. Luckily, we had some lifting help from Stevens Physical Plant and some traffic direction by Stevens Police.

Officer Gamez of the SPD posing with the team after helping us back in.

Avionics

The big focus of Day One was making sure all of our Avionics and Ground Control systems worked. To do so, we needed to take over a classroom, too. Ben found an empty room not too far away, overlooking the mechanical proceedings on Walker Lawn. Our ground control station was set up, and the wires started running!

All the wires serve three purposes: valve actuation, transducer reading, and real-time image processing. So far, the project has grown to incorporate 27 instruments. Eight of these require active actuation, and six send signals to ground control.

After double-checking that the radios worked (another important electronics test), Ben and Faris actuated each valve in the order that they will be used in testing. Though we didn’t have any temperature and pressure sensors set up, Ben also made sure the sensor code was running. Finally, we set up each of our three cameras — one real-time, one slo-mo, and one thermal — and they each came up on-screen!

Avionics Dry Run Testing: Successful.

Mechanical

Mechanical systems were being assembled throughout the avionics tests. All hands were on deck to set up the gantry hoist, test stand, and aluminum truss.

Rodrigo, Will, and Abe working on the test stand.
Will climbing the gantry hoist to adjust the winch.

These three metal structures will serve as the backbone for our propulsion testing. To restrict movement under fire, the rocket will be bolted to the 30-foot-long aluminum truss. (And tied down, twice-over.) In turn, the truss is bolted onto a short steel structure called the “test stand.” It sinks into the ground to provide added stability. In order to raise the truss, several cables run to another nearby steel structure: the “gantry hoist.” Equipped with a heavy-duty winch, it pulls the truss and rocket into place atop the test stand.

This process of raising the truss is what we tested. After a few preliminary tests and some iterative construction:

Checking calculations with a third of the truss section.
Supporting the whole truss before it goes up.

Some small edits to the gantry hoist before another pre-test. (Video has no sound.)

It went all the way up!

(Pardon Dakota’s yelling.)

By the time it came back down, it was nearing dark and threatening to rain. So we packed up and vowed to raise a weighted truss another day!

Day Two: Friday

It rained all day Thursday. Bummer. Luckily, we had the lawn reserved Friday, too. So we got back out there at 9:00am and went to work!

Step One: Check Everything

Even though everything had been set up on Wednesday, we needed to make sure everything was ship-shape. Even the slightest wiggle room on a bolt could send the whole thing crashing down. Not optimal.

Deputy Chief DiGenova of the SPD making sure our Test Stand was in peak shape.
Making sure the gantry hoist’s support cables were taut before testing.

Once happy, we jumped ahead to where we left off: Adding weight to the rocket. Our first subject? Our very own Abraham Edens.

Step Two: A Small Amount of Weight

It didn’t take much coaxing before Abe was hanging upside down. Who doesn’t want to say they’ve hung like a koala from a truss and elevated eight feet in the air?

Abe being raised to Height #1 for the first time.

To check all of our structural components, the truss first took Abe up to about six feet, then up to eight. Twice. (You can see more in the time lapse video below.) After Abe had had his fill, we gave Tom a go as well.

But all this wasn’t just eight college kids goofing off with a 30-foot truss. There was actual science behind it. Before loading up our testing equipment with 500 pounds of wood and concrete, we wanted to be sure that it could repeatedly lift human-sized cargo. And it’s a good thing we tested it out first. We were successfully able to raise both people, but the winch slowed down to a snails pace. This indicated we would need more powerful equipment for the full rocket.

Time lapse footage of both of Abe’s adventures up the truss. (Video has no sound.)

Step Three: Time to Buy Some Stuff

We took a lunch break. After all that heavy lifting (and being lifted), it was time to eat some food. We also took the chance to buy a heavy-duty winch — then the car battery to operate it.

Will and Nathan got to work installing the new winch atop our gantry hoist. Once it was up, we were all ready to go.

Step Four: Fake Rocket, Real Results

500 pounds of concrete is heavy. Our 2-ton pneumatic engine hoist was busy elevating the aluminum truss, so we lifted and moved the fake rocket by hand. Talk about a workout. Coupling the surrogate rocket to the truss required moving it ten feet to the west, then elevating it while another team member temporarily secured it with ratchet straps. Then, three linear rails permanently mounted the rocket to the truss.

But after all that grunting and sweating? We got to stand back and watch this:

Pardon the abrupt switch from landscape to portrait. (Video has no sound.)

So, there we were. Eight rocket engineers standing out on Walker Lawn at 11:45pm on a Friday night. Covered in mosquito bites, still sore from lifting a fake rocket, and getting kinda hungry again. But in front of us was solid proof that our testing structures would support the weight of our rocket.

Gazing up at the fruits of our labors at 11:45 Friday night.

In fact, the fake rocket we lifted weighs more than the rocket parts we will use in testing. The dummy rocket’s 500 pounds accounts for the weight of the entire rocket — when, in testing, we won’t be adding the fins, nose cone, or fuselage. So, really, we have a built-in Factor of Safety greater than 1.0!

Step Five: Teardown

As much as we all could have stood there for hours just gazing up at it, we took it down in a hurry. After all, it was nearing midnight and all of us were tired from two long days of testing. We packed up the U-Haul with all of our materials, leaving behind only the test stand, rocket, truss, and pneumatic hoist for Saturday morning.

Though it looks like someone landed a plane on Walker Lawn, this is what our testing apparatus looks like all wrapped up!

We found out it took even more work to take the rocket off the truss than it took to get it on. So the remaining construction was wrapped in a tarp, and we finished taking it apart the next day. And just like that? We called it a successful Dry Run Test.