Unusual first post of procrastination

Hi, I’m Sarah… Now that’s out the way let’s get onto the other stuff…

I’m six months or thereabouts from finishing my PhD and therefore will cease being a student which will end up with my release back into the wild to fend for myself in the rabid world of academia. However writing a thesis is singularly the most difficult and tedious task you can ever imagine. Worse in fact, than any of the menial jobs I have found myself saddled with in the past, and that includes the time when the rubber washing up gloves proved to be a terrible choice when unblocking a toilet in a nightclub. Rubber gloves are very useful in keeping your hands away from things you’d rather not be in contact with, however they are also remarkably good at holding vast quantities of toilet water when you least expect it and then refusing to release you from their kung-fu like grip.

So yes, I am supposed to be writing my thesis but instead I have found myself finding all manner of things to do but write (much to the annoyance of my professor) and the past few weeks I have found myself spending more and more time on the simulation of rocket motors rather than my other work. It’s an interesting problem and one I’ve been interested in for more than half my life. The other half was a mish-mash of sleep, drinking, loud music, more sleep, food, coffee, and the acquisition and reading of books.

So now onto the good stuff. I have been playing a lot with Matlab recently trying to model how the solid fuel grain regressions as the fuel is consumed for different types of core shapes that are used in rocket motors. I’ve also done a lot of work modelling small gas turbine engines, micro-turbofan engines, ramjets as well as aerodynamic behaviours such as wing vortices and rocket trajectories. All of I will find time to cover over the next few weeks along with snippets from my research and anything else that interests me, I mean who needs to finish a thesis right…..

Oh and while this is my first post I suppose I could dive into one interesting thing that I’ve seen cropping up on forums is the allegations regarding fake missiles photographed in a North Korean military parade. The missile in question is shown in this picture with the ‘evidence’ of the potential fakery highlighted.

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Whether the missile itself is a mock up or real the point is the design isn’t fake and has appeared on a number of other missiles over the years, including an early British surface to air missile known as the Thunderbird [1], also note the canting of the booster nozzles as well!

English_electric_thunderbird_in_1960_arp

The reason you would want to use such an unusual design is primarily down to two factors, the first being the offset nose cone would provide some degree of asymmetrical drag which would help to separate the boosters away from the main fuselage during jettisoning. Another reason may be down the interaction of the shockwaves that form from the cone and the rocket’s fins and fuselage. If anybody knows of any other reason I’d love to know.

These shockwaves are unsteady which means they vary over time, this could lead to unwanted vibrations which could then generate areoelastic effects, such as fin flutter, or even produce errors in the guidance system sensors. The aerodynamic interactions between the booster and rocket is likely to be a highly complex system and no rocket engineer would ever make the mistake of just sticking a nose cone on at any old angle, at least I hope not….

Sarah

[1] Photo, courtesy of Adrian Pingstone (Arpingstone)

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