June 2019 - Castle Point Rocketry

Dolly Upgrade!

June 25, 2019June 5, 2020
by Nate

Initially, we built a dolly out of 80/20 aluminum to wheel about the rocket. This dolly proved to be too short as our rocket got longer. So, we decided on an upgrade — wood! This new dolly is double the length of the previous.

Abe fills the new dolly’s tires with more air so it works extra-well.

Over time, our rocket has only gotten longer. (At least, after it’s initial shortening when we moved from a two-stage system to a one-stage system.) Our rocket is around 25 feet long. This dolly will be used to transport it around the test and launch sites.

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.

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Dry Run Test #2 (Teaser)

June 14, 2019June 5, 2020
by Dakota

It’s June 14th! You’ve caught us mid-test! So, let’s break these last few days down…

4,000 square feet of grass. 2,000 feet of fiber optic cable. 1,200 feet of Caution tape. 770 cubic feet of U-Haul space. 120-volt generator. 30 feet of truss.

10 seconds from the heart of campus. 9 o’clock start time. 8 team advisors. 7 valves. 6 visitors and counting. 5 walkie-talkies. 4 days. 3 structures. 2 tests. 1 fake rocket.

Keep an eye on our Instagram (@cprocketry), Facebook, and blog to see how it goes!

News

Industry Advisor Review

June 14, 2019June 5, 2020
by Dakota

It was June 10th, 2019. A thick, foggy mist had swallowed up New York City. Hoboken traffic was, unsurprisngly, backed up half an hour. And in the back of a machine shop at Stevens Institute of Technology? Nine rocket enthusiasts were ironing out a testing procedure.

Castle Point Rocketry invited our industry advisors, Rich and Luke, in to review our final testing procedure. Somehow, there were still some introductions to be made, too!

Rich Kelly (left) and Luke Colby (right) introduce themselves before we get to work.

Luke Colby is the President and CEO of Triton Space Technologies, providing engineering design services out of Boston, Massachusetts. Luke has been advising our project by phone since Fall 2018, but we have never met in person. His company also manufactured a handful of valves that will travel aboard our rocket.

Rich Kelly is a Senior Project Engineer with Valcor Engineering, based in Springfield, New Jersey. Due to Valcor’s proximity, he has visited our lab many times over the last few months. And they also manufactured several valves we will be launching into space!

After introductions, we quickly showed Rich and Luke the latest work we had done on the rocket. Then, it was down to business.

Sitting down to hammer out the details of chemicals testing.

We crowded around an imaginary table in our makeshift conference room. (Spoiler: It’s our lab with a portable projector screen.) We had less than six hours to go through the entire 64-page Propulsion Testing Document, so… there was little time for games. (There was, however, time for lunch. Self-care is important and, as Rich reminded us, “The food’s not getting any warmer!”)

The team led Rich and Luke through our testing plan page by page, halting when there were questions or suggestions. After reviewing three tank tests, five full-stack tests, and ten procedural methods, we reached the end of our packet. We called it a day, but Luke and Rich left us with a few pointers. Among other things, the team is revising our waste management plan, redesigning the igniter (again!), and renting more robust pressure regulators.

Just some happy nerds doing space stuff.

It was then time to set our sights on the next big exciting task: Dry Run Testing!

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“Clean For Oxygen Use”

June 11, 2019June 5, 2020
by Dakota

We can all probably agree with the relative levels of cleanliness. Around the bottom of the scale, there’s “I Am Comfortable Living In This.” A little more clean, you probably find “Company is Coming,” closely followed by “My Parents Are In Town.” Near the top of your list, you probably find “Apartment On The Market.”

“Clean for Oxygen Use” may top the charts. It’s certainly not a household standard.

Bottom shelf: Unclean. Top shelf: Clean.

This cleaning method is the entire reason we constructed our clean room. Much of our rocket will come into contact with high-purity oxygen, whether in liquid or gas form. Gaseous oxygen loves lighting things on fire, and liquid oxygen freezes most substances solid — so we need to be sure everything is as clean as humanly possible. To do so, we have a six-step cleaning process.

Step One: Alcohol Bath

After we identify a subassembly to clean, we remove each piece from storage. We bathe each individual fitting, pipe, adapter, and valve in isopropyl alcohol. (That’s the same alcohol you put on wounds to clean them.) For 12 minutes, they rattle around inside an ultrasonic chamber. By vibrating them very, very quickly, the machine dislodges defects, dust, and other gunk that is clinging to them.

Our ultrasonic bath is located on the left.

Isopropanol is also a dehydrant. This agitation bath ensures every out-of-the-way nook and cranny is water-free. Any water left in the system would freeze in contact with cryogenic liquids, decreasing functionality and making the rocket explosion-prone.

Step Two: Nitrogen Purge

After they’re removed from the bath, each part is individually inspected for remaining debris.

A tee junction during the nitrogen drying cycle.

Then, every part is dried with a pressurized jet of filtered nitrogen. Not only does this ensure no isopropyl alcohol is left on the part, it blows away any remaining foreign materials.

Step Three: Alcohol Rinse

As if Step One weren’t enough, we then subject each component to yet another round of alcohol. This time, the isopropanol is targeted in a stream. The entire part is washed beneath a squeeze bottle before moving on to Step Four.

A tee junction having an isopropyl alcohol shower.

Step Four: Nitrogen Purge

More drying! Like most alcohols, isopropanol is flammable so we need to make sure each part is bone-dry before assembly. This last round of nitrogen is usually enough to get the last bits of stubborn junk off of our fittings.

Step Five: Critical Inspection

Once the second nitrogen blow-down is complete, we are fairly certain nothing remains. But just to be sure, though, we inspect each piece from every angle for leftovers. Inside and outside, nothing is allowed to escape our prying eyes. And on the off-chance we still find refuse holding on? We restart the whole process from scratch. We bought smaller ultrasonic bath just for that purpose.

Step Six: Assembly

Finally, we are sure that our parts are Clean for Oxygen Use. We bubbled, tossed, dried, washed, and dried most everything (and even brushed some with a high-grade pipe cleaner), and it’s time to put the pieces together. One by one, being sure not to stir the air or drop anything, the rocket starts taking shape. We have 24 subassemblies ranging in size from one component to thirteen.

One of the subassemblies we will be using for tank testing.

Each über-clean subassembly is then given a new home on the high shelf in our clean room. Small subassemblies are bagged and given a unique name so they don’t get confused down the road.

And that’s how you make a rocket Clean for Oxygen Use!

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Igniter Test #2

June 11, 2019June 5, 2020
by Dakota

Late last week, Castle Point Rocketry ran a successful test of our new igniter design. It is a variation on a theme (see our previous blog). This new model allows for better manufacturability and repeated use, but doesn’t sacrifice the engine-within-an-enigne design we wanted.

Many individual design components have changed over the last month. The fire now shoots down instead of up. There is a bored hole at the bottom so that the igniter can be removed from the engine quickly. We filed the top to a point so it fits into the engine more easily. Beyond that, it’s very much the same part.

Before testing.
After testing.

As you can see, we had a small meltdown problem, consistent with the last test. It’s a good thing that 3D-printed plastic parts are as printable as they are disposable!

Tom designed a gravity-driven system to quickly remove the igniter from the engine. By topping a vertical pole with the igniter, we can easily drop the assembly from the engine after ignition.

Now, we begin the process of moving forward. Our current goal is to outsource manufacturing to a local New Jersey company capable of machining it out of aluminum. That way it’s quick, close by, and made in the USA!

News

Fully Recoverable

June 6, 2019June 5, 2020
by Dakota

From the onset of our project, we were certain of one thing: We wanted to recover our rocket. By recovering the rocket, we would be able to reuse many pieces of the system and redundantly check our data.

So when our team found Fruity Chutes, Inc., we were ecstatic. Here was a company which could provide us with a drogue chute and main chutes — and to specification! You may recognize the pictures below… They are from our first round of “official” drogue parachute tests in December.

Will was happy with the Drogue Parachute Visibility Test.
Nathan gave the Drogue Parachute Spin Test his all.

Originally, Castle Point Rocketry planned to utilize one drogue parachute and one main parachute. The drogue parachute would deploy at maximum altitude (or “apogee”) and help the rocket fall in the correct orientation. Once the rocket had fallen most of the way back to Earth, our main parachute would open up. The main chute would provide drag (and added visibility) to allow us to track where it fell. It would also ensure the rocket didn’t impact with a big *splat*.

But, as with much of our project, the parachute system has undergone some iterating. Due to our rocket getting longer and heavier over the last few months, we needed more surface area. (More surface area creates more drag, the resistive force which slows the rocket’s descent.) Rather than buy a bigger chute and scrap our first, we decided to buy a sibling. We now have twin main parachutes!

Will counting all the pieces before Tom and Abe pack it up.

Those of you who follow us on Facebook probably recognize this picture. (Those who don’t should go follow us pronto!) The first half of this week, we’ve been busy making sure all of our recovery system will fit in the rocket.

As you can see, here is one more subsystem ready for testing and launch. Everything’s leaning towards a successful summer!

News

Preventing Meltdown

June 4, 2019June 5, 2020
by Dakota

One of the concerns with an active rocket engine is what comes out the hot end. Particularly, how hot the flame is that comes out and what we have built to stand in its way. Currently, the team has designed testing and launch stands that minimize the infrastructure that the flame could reach. Just in case, though, we want a backup plan.

That backup plan comes in the form of a metal shroud — hand bent by the team — which fits the form of the stand. And just in case a sheet of aluminum alloy wasn’t good enough, we coated it in a layer of intumescent caulk.

The caulk provides the red, tacky texture seen here.

“Intumescent” refers to a material’s ability to grow when an external force is applied. The caulk that we bought chemically breaks down and grows in volume when a flame is directed at it. The resultant polymer/carbon mass provides additional thermal insulation to the structure beneath it.

Testing Theory

In order to prove that it works — and decide how thick we needed to apply it — we ran some tests. The first round, we tested six different caulk thicknesses for a set period of time. The second round focused on the two best candidate thicknesses at various flame angles.

To judge which test worked best, the temperature on both sides of the test strip were taken every 5 seconds. An infrared thermometer gauged the temperature on the back; a thermal camera estimated the front.

The Outcome

We got a definitive answer from the test: Coat the stand shroud with 1/8″ of caulk. This thickness performed the best at all angles we tried — and leaves us more than enough caulk to coat two more shrouds, if we need to.

The caulk certainly did its job. The photos above show what happened to uncoated versus coated aluminum alloy sheets after a minute of direct flame. The uncoated sheet… melted. The coated sheet remained rigid — and sprouted a dense forest of curly, black char.

The intumescent caulk expanded by a factor of 4.25.

The 0.1″ caulk thickness provided optimal thermal resistance. Directing the blow torch at the center of the sheet raised the back temperature only 6°C — not nearly enough to melt any metal we’re using.

So yeah. We feel pretty comfortable covering our test stand shroud. One step closer to testing…