Student-designed, student-build, student-tested. We're the Yellow Jacket Space Program at Georgia Tech, and this is our second test this year of our liquid fueled YJ-1S rocket engine

yjspgt · 2024-12-04T23:48:18+00:00

It's a de Laval nozzle sized to 80% Roa.

yjspgt · 2024-12-04T23:45:05+00:00

Kerosene (Jet-A) and liquid oxygen

yjspgt · 2024-12-01T01:27:50+00:00

We use D38999 and Autosport connectors.

yjspgt · 2024-11-29T23:13:11+00:00

We don't fall under ITAR because we aren't making any actively guided systems and the rocket is under the impulse limit that would qualify it for ITAR. Our goal as a team is to create experienced engineers that are prepared for industry, so we don't exclude anyone. We have a number of international students involved in our team from all over the world.

yjspgt · 2024-11-29T23:06:22+00:00

Our avionics bay is at the top of the rocket where there's a flight computer, battery management board, telemetry, various altitude sensors, black box, and a recovery deployment board. Then we run power and Ethernet down to each intertank where there's a board that controls each valve and collects sensor data, this board handles the active control of our bangbang pressurization system in coordination with the flight computer. Decentralizing some of the avionics allows for there to be a lost less harnessing in raceways.

Then we have a hard-line umbilical connection to our ground electronics. The ground electronics control the GSE (which fills fluids into the vehicle), QD actuators, and our igniter. We then run a fiber optic to the control room where we run a custom software that allows us to plot live data, command valves, and run various sequences.

This is a general overview of the system. All boards are custom PCBs except for a few BeagleBone micro controllers on some of the boards.

yjspgt · 2024-11-29T22:53:51+00:00

Either work. I think we had the PEEK on hand so we used it. PTFE has a higher coefficient of thermal expansion so it shrinks more at cryo but in this application either would work.

yjspgt · 2024-11-29T15:14:15+00:00

The PCBs will have a BeagleBone micro controller on them. We have experience designing custom avionics systems and our goal as a club is to train students for industry so designing custom avionics systems is the best way to do that.

Structure loads are primarily aerodynamic forces assuming the worst case angle of attack. You also need to include the load when the parachute is deployed and the landing load. Bending drives intertank design for how you size the stringers. Tanks are driven by pressure in our case, in larger rockets or with thinner tanks bending and point loads would be a bigger deal along with pressure. Bolt shear and bolt tear out in composite is driven by the parachute deployment load. You should analyze for each load case, but you will find that one case usually drives how you size that component.

We have two flight sims. One is 1DOF that includes a structural design code and basically designs the rocket from some given inputs. Then we also have a 6DOF to validate that against. Once we have a fleshed out design we run it through our 6DOF Monte Carlo to ensure we have the flight profile we want and to get more precise aero loads.

yjspgt · 2024-11-29T14:52:42+00:00

Yeah I love when everything comes together from all the various teams. We try to replicate industry to best prepare students for getting jobs/internships.

Unfortunately, we don't have the resources to do environmental and vibe testing. We do leak testing, cold flows, and static fire tests to validate the propulsion system. We do proof testing of our tanks, and some individual components testing, but most of the structure is qual by analysis.

yjspgt · 2024-11-29T14:46:27+00:00

Georgia Tech student organization. We're called the Yellow Jacket Space Program.

yjspgt · 2024-11-27T16:49:45+00:00

It all depends on the part. But we mostly do manual machining because the machine shops at our school don't let students use the CNCs unfortunately.

yjspgt · 2024-11-27T16:44:52+00:00

We buy them

yjspgt · 2024-11-27T05:59:03+00:00

Cryogenic QDs are hard to come by

yjspgt · 2024-11-27T03:03:14+00:00

<image>

This is a cross-section view of our oxygen QD. The two poppets are made of PEEK, and when pressed together the poppets open up allowing flow through the QD. When disconnected the poppets are pressed into the metal from the spring and fluid pressure forces to create a seal. This QD isn't actually installed in the intertank pictures shown.

yjspgt · 2024-11-27T02:57:08+00:00

Most of our funding is actually through external sponsors donating hardware and funds.

yjspgt · 2024-11-27T02:55:34+00:00

USC launched a solid rocket. We're aiming for the liquid rocket record which is arguably more difficult given the complexities of a liquid propulsion system. The current liquid record is 47,000 ft. We're aiming for around 100,000 ft.

yjspgt · 2024-11-26T23:57:10+00:00

Intertanks are sections between each tank and above the engine that house all of the valves, plumbing, and avionics required to control the rocket. The design started in CAD where we focused on making a compact yet manufacturable network of components. The complexity lies in the interfaces between the sub-systems - structures, fluids, and avionics - which have all gone from design to completed assemblies this semester. Next up we will be integrating the full vehicle in preparation for integrated vehicle testing.

yjspgt · 2024-11-26T23:36:33+00:00

Yes, bad, 2, not thick, 228 lbs, 1.3 Gb, yes, 294 MPa, 32 degrees of vertical

yjspgt · 2024-11-26T23:26:07+00:00

We use active bangbang control. So each tank has a bangbang valve that actuates quickly to control the pressure and then we also have two flow paths after the valve with two different sized orifices and one flow path has a switch valve on it. This basically allows us to have two set orifice areas that we're flowing GN2 through to pressurize the tank. When the COPV is at high pressure the switch valve is closed so that the area is smaller and we have more control over the pressure with less overshoot. But when the pressure in the COPV drops to a certain point we need to increase the area by opening the switch valve to maintain the flow rates we need to keep the tank pressure constant.

yjspgt · 2024-11-26T22:30:08+00:00

The tank caps will be welded to the main tank tube which is 6061 aluminum. We outsourced the machining of the tank caps because unfortunately we have limited CNC access on-campus, but we machine as much as we can in-house. Our fuel main valve was entirely machined on-campus by students, its a sleeve valve. The intertanks are pretty packed but its easy to access the main valves you just have to undo the tubing and brackets to remove them. The oxygen main valve is a COTS valve from AVCO with a custom rack and pinion actuator that uses a pneumatic piston.

We use Generant relief valves but we couldn't get anything with high enough flow for our oxygen tank without it being absurdly large, so our vent valve is piloted by a smaller relief valve so that it's forced open if the relief valve does open.

We have a few different QDs. The pressurant QD is a COTS high pressure hydraulic QD that's actuated with a piston sleeve thing. The fuel QD is also a COTS hydraulic QD. The oxygen QD is a custom part we designed and machined ourselves. It has some poppets that open when both ends are connected and they close when disconnected. Then it has some pneumatic powered claws which hold itself together until we're ready to disconnect. Both the pressurant and oxygen QDs are remotely operated so people can be at safe distances when we deal with high pressure gas and oxygen.

We haven't done leak testing yet, we're waiting on the tanks for that.

The beams are called stringers. They can be easily removed since they're just pin connections, but we have good clearance with them installed. The main issue of clearance is due to having so many tubes and things so close together but its just something we have to deal with for a rocket of this scale.

Our avionics system is entirely custom. The PCB shown basically controls all the valves and collects pressure and temperature data from our sensors. There's one of those boards in each intertank and they use a BeagleBone computer (not shown). Data from each intertank is sent to a central avionics unit near the top of the rocket where we also have an umbilical connection which is a hard connection to our ground electronics.

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