test stand Archives - Castle Point Rocketry

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

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.

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…

News

Ready, Set… Launch Stand!

April 3, 2019June 5, 2020
by Dakota

A few weeks ago, we shared how excited we were about our truss being delivered. Now, the fun of building it.

Throughout our interview with techdrawer this past Saturday, Nathan was hard at work assembling the launch stand that our truss will stand on. When our day with techdrawer came to a close, he convinced Dakota and Ben to run through the hoisting process with him.

You can see the launch stand in the photo below to the right of the blur-that-is-Nathan. It’s rectangular and made of steel.

Behind the Griffith Building preparing to hoist the truss onto the launch stand.

The hoisting process involved several meters of cable, two steel structures, nineteen cinder blocks, three humans, one ladder, and three three-meter lengths of aluminum truss.

After bolting the lengths of truss together, we lifted it with an engine hoist and attempted to lever it up with cables and pulleys. The first attempt didn’t go so well. The truss ended up balanced on Dakota’s head while Ben, up the ladder, steadied it and Nathan retied it to the hoist with a complicated series of climbing knots

The final product. Excited Nathan, to boot.

72 hours later, CPR tried once again. We had a modified launch stand, two more Mechanical Engineering majors, and better lighting to help this time. And were we successful? Well, Nathan’s smile in the picture above should answer that!

Uncategorized

Changing Plans

February 28, 2019June 5, 2020
by Dakota

If you look at our BOM (Bill of Materials, keep up!) you’ll catch us in the middle of a very important decision. How are we going to test our rocket?

The Purpose:

To be sure our design works, we need to have data on-record from a simulated run. This includes measuring the lifting force generated from combustion, the temperature of the engine chamber, and the fluid pressure at a few key points along the plumbing.

It’s also an excellent chance to test our dump, abort and kill sequences in case of emergency down the line.

Plan A:

From Day One, it’s been clear we would need to test the full stack. Otherwise, how could we be convinced it would work before launch? Since our propulsion system is pressure-fed, the tanks need to be tested vertically. (If the rocket were horizontal, our high-pressure helium would be able to flow right through the tanks when they’re half full, rendering the test futile.)

Proof that a horizontal test is no good. We would lose pressurant before we were halfway done.

This means we have to test vertically. Right-side up. Which, with rockets, is also the direction you point them if you want them to leave the ground. Not as much the plan, with a static fire test.

To get around this pesky bit of physics, the team designed, modeled, and specified the materials in our BOM for a full-height, vertical test stand. Essentially, we designed a cylindrical sheath (for containing the rocket) inside a rectangular frame (to provide structure) weighed down with water, sand, and concrete (so it didn’t fly away).

A full CAD render of our initial vertical test stand, complete with counterweight barrels.

The Problem:

Upon igniting the engine, the nose of the rocket would be forced upwards into the integrated force sensor. This is unrealistic launch behavior, since it puts the entire rocket in compression. Alternatively, the rocket pushing upward into the stand can be viewed as the stand forcing the rocket down

Plan B:

Back to the drawing board. We needed to come up with a test mechanism that would better simulate launch by placing the rocket in tension, rather than compression. As it turns out, the best place to turn for inspiration is still the Internet.

The verdict? “Tie it down.” Plain and simple. All that’s needed is a rocket, something tall to hang it from, and a few (very strong!) wires to secure it to the ground. It may sound silly, but there are plenty of videos detailing the process and showing positive results.

A quick sketch of our new vertical testing plan.

It requires less logistically, too, as it no longer requires us to maneuver an expensive rocket inside a bulky steel cage. Sold.

What Now?

Now we continue the process of finding a place to launch. We have yet to nail down an official location, but we’re zeroing in pretty quickly. (A few amazing spots have jumped out at us this week and we’re following up.)

And after that? We build, we go, we test.

News

A Spooky Update

October 31, 2018June 5, 2020
by Will

Between our new box, our crowdfunding campaign (which has been extended by a week – go check it out), ordering test stand and avionics parts, and safety meetings, we’ve got a lot going on; it’s all very exciting!

We’ve already raised over $20,000 from our crowdfunding campaign – a huge thank you to everyone who has contributed to this amazing milestone. Every dollar donated brings us one step closer to reaching the Karman Line!

Very soon, we will begin construction of the test stand (partially shown in the CAD above), and preliminary testing on our electronics, so stay tuned for future updates here and on our social media!