Saturday, July 23, 2016

Rocket Design Competition: Summer 2016 Begins!

It's that time again!

And as Project Chair for the AIAA (American Institute of Aeronautics and Astronautics) at UCF, I find myself viewing the Rocket Design Project in a slightly different light. It's still the same ball of fun - design a rocket to meet a specific goal, model it's flight, build the rocket, launch the rocket and measure your performance against your model and the goal - but seeing the behind the scenes, I understand some of the limitations that have been placed on the project this summer.

Because the project is being completed in half the time, there are more design restrictions to ensure rockets that will fly safely. Additionally, we are launching in a national forest, so the risk of starting a fire is a touch higher. So I'll concede and not aim for 2,200 feet like I was planning. Maybe next semester. They are also basically only letting us design our fins, this time. No cutting down (or completely discarding...ehem) body tubes or motor tubes. But since our goal is to get as close to 1,500 feet (457.2 meters) as possible, we want the weight. We are using the same formula as last time, although I want to modify it to account for any crookedness in the launch rod and do a weighted average of it and OpenRocket's prediction. We are also using SolidWorks - which I am trying to remember after using nothing but Creo Parametric for about six months now - to obtain a coefficient of drag via FlowSim.

So summary completed, it's time to talk about our plan. Our team intends to run headlong off a cliff and never look down, because that's how you fall! I'm not saying that I tried to get permission to launch a small anvil-shaped payload that would also serve as our weight, or that our rocket will be a dismal failure, either. But I am suggesting that if it does fail, no one should be surprised. After all, it is an ACME rocket....

"An ACME rocket?" I hear you say. Yes. The ACME Rocket Team is attempting to produce one ACME rocket (probably less the cross-hairs) this semester, slip it past all inspections, and see just what it does. Powered by a G40-7W, it will do something. And it will be memorable. We are hoping it'll be the good kind of memorable.

At this point, we have created a model of the rocket in OpenRocket, a rather nice open source program for modeling the flight of rockets. While it's predictive capabilities are pretty good, it does tend to be about 10% optimistic, so we are going to also do hand calculations and use a weighted average of the two to set our weight. But for now, we have a rocket design and fin design that will overshoot the mark. Once we get our hand calculations going, we will add weight to lower ACME 1's apogee and tweak its stability. I'm personally aiming for a modeled stability of 1.3 calibers, so any slop in manufacturing won't push us too stable or unstable.

I've also been working up a CAD of our rocket in SolidWorks. This has been a "fun" process, especially since I never tried to make such curvy fillets between things like concentric tubes (launch lugs). The process has been a good learning experience, and by that, I mean I have lost much hair and a touch of sanity over this. So where does the design stand right now? Right about here:

So what do you think? Does it look like an ACME rocket? Is the inspiration at least present? Heck, do you think this will get off the launch pad?

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