How to Launch a Rocket to Space: Inside BURPG Part 4

Sorry for the long pause on the updates, but the past couple weeks for BURPG have been incredibly busy. Part of what we did was start the planning process for next year. This includes electing new board members and coming up with a new project idea. Yours truly got elected as the Director! I am very excited to undertake the role; it should be a challenge, but one I am excited to meet.

We also have a game plan in the works for next year. Assuming the Starscraper launch goes well this summer, we need something new to work on. We are planning on starting a liquid engine development program, which will take about a year. The following year will then see the development of a hovering rocket platform (read Grasshopper) using our engine.

The Starscraper design and technology will be made public to some extent, since our goal is to help further education about aerospace.

Click through and see what we have been up to! There are some really cool videos from a test, which was the first confirmed use of liquid injection thrust vectoring on a hybrid rocket!!

First, we will take a look at ASTRo, our Actively Stabilized Test Rocket. ASTRo is the first actively guided amateur rocket to be approved for flight. The launch is going to be in January in Texas. ASTRo serves two purposes: First, it is a test case for future launches of amateur actively guided rockets. There is a stigma against actively guided amateur rockets, and we are hoping this will open the doors for future groups to attempt active guidance. Second, ASTRo is a development platform for our active guidance algorithm that will be used in the Mk V rocket. Where the Mk V uses liquid injection thrust vector control, ASTRo uses control surfaces on the fins. Despite this difference, how the system reacts depending on the rocket's orientation is the same. ASTRo is going to be launched vertically, and then any weather cocking (tipping due to wind) is going to be countered by the control surfaces on the fins so the rocket will fly vertically.

On the Mk V, the thrust vectoring is achieved by injecting nitrous oxide (laughing gas) as a liquid into the side of the nozzle. It evaporates instantly, creating a shock wave that deflects the thrust. This functions to keep the rocket vertical during flight. The Mk V has no fins, so it would otherwise tumble.

For those wanting some more technical details on ASTRo, it is made out of fiberglass, except for the black component at the bottom of the rocket. This is a 'fin can' which is 3D printed. On the bottom are servos, which rotate the control surfaces on the fins.

The Mk V rocket is coming along! we got the tank in, which really drove home how how big this rocket is going to be. Keep in mind, this tank you see in the pictures is less than half the entire rocket. To get the rocket into the basement, where our lab is, we have to go in through the window. Once the rocket is assembled, its going to be slid out the window onto the test stand, whose collapsed angle matches that of the ramp. The fully assembled engine (as used for static testing) is 24 feet tall, with the whole rocket being 32 feet tall.

It goes without saying that we get some strange looks (and interrogation by an incredulous cop) doing this.

We are also working out some of the finer details on the Mk V CAD, including the plumbing, wiring, board and battery installation, and internal systems. These are the specifics I cant reallllllly share openly on the internet. But once things are complete there will be some pictures I can share!

This was the highlight of the past several weeks.

By the time the last article was written, we had done two tests, both ending in nozzle failure. Since then, we have done 5 separate tests. The first test, we had a faulty abort fire, which led to a full duration burn producing almost no thrust. Then, the next weekend we had two tests lined up. Neither happened, since both times the igniter did not fire. Our igniters are model rocket fuel grains, and the ones we were using were a slightly different formulation than we normally use, which we feel suffered humidity damage despite normal storing procedures. That brings us to two weekends ago.

WE GOT FULL DURATION BURN!!!!!!!!!!!!!!!!!!

This was one of the most satisfying things I have ever seen. This was the first test of the day. We got 20 seconds of burn, with thrust vectoring. This is in the first video, which is multiple camera angles edited together. If you look closely, you can see the plume under the rocket shifting side to side as the thrust vectoring is fired. This test marks the first test that we could confirm of liquid injection thrust vectoring on a hybrid rocket motor.

Then, we went back out this past weekend and GOT ANOTHER FULL DURATION BURN!!!!!!!!!!!!!!!!

This is the second video, which is just a single camera angle. After about 10 seconds of burn, the liquid injection thrust vector control (LITVC) is turned up from half open to full open. You can see the entire plume deflect to the side. It is really cool to see how instantly it responds. This is how the Mk V would steer itself in flight.

Just watch the videos. I don't have anything else to really say.

As part of planning for the future testing, we had to make a Rev. B of Hyperion. This was for several reasons:

-Rev A could only measure positive temperatures. We realized we would like negative temperature measurement to calculate the density of the nitrous oxide entering the rocket from the tanks. So this capability was added for Rev B.

-Some of our ground valves are being switched over to solenoids, which require power delivery that Rev A could not provide. Rev B can control 4 solenoids

-We needed more pressure transducers. Because 8 is not enough.

-There were some ground plane noise issues with Rev A that Rev B is supposed to fix

-More expandibility? So how about 32 repurposable pins on the microcontroller? Should that be enough?

We ordered our boards through Advanced Circuits, who has been our manufacturer of choice for the past year. Im going to take this time to put in a plug for their customer service, which has always been fantastic. They pulled through for us on getting these boards. They have some great student pricing deals as well. But the service pays for itself.