 Rhaid i'n bwyda, rhaid i'n bwysig i'r ffwrdd. Felly mae'n rhaid i'ch gael i'r EMP, ydy'r ffordd a'r ysgol. Yn gwneud y gallai hwb am roeddwl. Yn cael ei ffordd i'r ddiwedd. Yn fy nifer yw'r hynny, mae'r ffordd i'n ddysgu gan eich morhofi ynghylch i ysgrifennu Lleithydd Gweithgol yn ysgrifennu Lleithydd. Felly, roeddwn i'n ddyn nhw'n ffordd i'r roeddwl dette yn hyn i'r llunio fyddion ac ymdangosio'r rhan o'r penwnol ffóch Rydym wedi'i cwestiynau, dwi'n mynd i ddechrau'r penwnol, a gaffelio'r pennau. Wrth ddechrau, ond i'n mynd i'r penwnol ymgoelio, yr inŵr maes yn cyfieithio'r penwnol. Felly, o'n mynd i'n rhaid i'w marw, mae'n fyw'r rhaglau yn rhanion i'r cyfrifiad yw'r cyfrifiad. Ond o'n mynd i'n rhaid i'w cyfrifiad o'n mynd i'w cyfrifiad, oherwydd yn gyffredinol i'r rhaid i'w mynd i'w rhaid i'w cyfrifiad, ond o'n mynd i'w rhaid i'w cyfrifiad o'r cyfrifiad, mae'n bwysig o roi'i rhaglau. felly mae'r oedd y gallu'n gwneud â'r ffordd o'r dyflau gweithio'r ailfaint oherwydd. Dyma'r gwahanol yn gweithio'n gweithio ar Mars ac mae'n mynd i gael systema'r roi'r cymryd sy'n gweithio'r stiblio'n gweithio'n gweithio'n gweithio. Mae'n cael ei ddwylo'n gweithio cymryd. Mae'r wych yn ymddiad chi'n gweithio'n gweithio, ac yn llwg iddo yr wybodaeth, ond, unrhyw hwn yn bach o ddechrau'n rhaglaethol. Ond mae erdoedd GwRAY NW, mae'r rhaglaethau yn ddiddordeb, mae'r rhaglaethau yn cael ddweud, mae'r rhaglaethau yn pajodol, ac mae rewagaeth gael rhaglaethau ac yn cael ei gweithfawr. Rhydwch cyffredinol. Mae'r rhaglaethau o'r cyffredinol. Yr rhaglaethau mae'r cyffredinol gyda cuest. rightly change of momentum is velocity times mass flow rate. So what the means is that's how fast you're chucking your propellent out the back and the m dot is the rate of stuff that you're chucking out the back. How many kilograms per second are you getting rid of? It turns out, because rockets store their fuel on board them, you really need to worry about mass and optimising that. It turns out what you want is a very high v and a relatively small m dot to get a certain amount of thrust a'r wych yn ysgolfyddiant. Felly, mae'n gwybod gwellio. Dynamyx. Felly, rydyn ni'n rhaid i'r diogelwch ar y dyfodol. Felly, mae'n rhai'r wych eich gweld i'r ffordd y cyfnod o'r ffordd i'w gwybl yn ymwysig o'r ffordd ymlaen. Felly, rydyn ni'n meddwl o'r ddwy, os ydych chi'n digon yn ymwysig. Ond, rwy'n credu oherwydd, mae'n ffordd ymwysig. A'r bod yn ymwysig i'r ffordd ymwysig, iddyn ni'n dda'n ystod yw gwot o'r rhod i'r wahanol, ac mae'n wahanol, yntech chi'n mynd i'r awd rhath, i chi'n ddweud y troi sydd o'r rogedd, a gw Goo Llywodraedd yn gyfnog i'r rogedd o fynd i gyfnog i wahanol o'r rogedd a'r rogedd yn wych yn y pan niolio. Roedd ni'n o'r hwn, ac yn fi'n oeith gwybod unig o grwmp. Mae'r rogedd yn yn ystylo yn强fyngl. Ffordd yn gyn yr uned. The more it falls over, the more the gravity is acting upwards. The rocket doesn't work like that, it's actually in free fall. So if you let it go of it, it's actually going to fall like this. And the rocket won't rotate unless you do something to make it do that. That's another example of Newton's third law that applied to rotational systems rather than linear systems. So if I steer the rocket engine this way, that's going to cause a reaction that will make the rocket go the other way like that. If I steer it this way, it'll react back that way. So that's roughly how the dynamics work. And what happens is when you gimbal the rocket, it's called gimbling, by the way, swivelling the rocket engine, that puts a proportion of the thrust in a sideways direction and that's what causes the rocket to turn. And what happens is that that thrust will cause the rocket to turn faster and faster and faster and faster. So it's the angular acceleration that's proportional to thrust. So that's enough dynamics. This is how you deal with it. So this is a little control diagram. I don't have a pointer here, but on the left in the blue box you've got an IMU, that's an inertial measurement unit. So that's essentially a thing that measures what way up the rocket is. You've then got a controller which makes sense of that data from the IMU and then you've finally got some actuators which will do something to the rocket. Now the one I've just showed you, that's called a gimbal actuator, but you can also use cold gas jets and all sorts of other methods to actually steer the rocket. That then feeds back through the vehicle dynamics so it makes the rocket do something. That then changes the readings that you get on the sensors. And the sensors that you'd have there usually be three-axis gyros and three-axis accelerometers. So gyros give you rate of change of angle and accelerometers give you rate of change of speed in sideways directions and up-down directions. So this is a little bit of history, sort of how this project started. It started when I was a student or I think I was just moving into my first job also at a university. And I was really inspired by this thing. So this is a thing called the Delta Clipper, McDonald Douglas DCX. It then became part of a NASA programme. It sadly didn't go very far. They had a couple of accidents with it, which wasn't really anyone's fault. The essential design was very sound. And this was a rocket that could take off and it could move sideways and it could land again on a pad. And it was a technology demonstrator for all sorts of different things. It was built very quickly in a very cost-effective manner. And it's really a good example of how to run a really quick, cheap aerospace programme that does something really amazing. So the question is, so there I was without access to modern MEMS gyroscopes or they were just becoming available for model helicopter pilots. So this is going back to 1995 sort of time. So the big problem is how you make a gyro so the rocket can tell which way up it is. And this for somebody who's essentially operating in a basement with limited tools and technology is a really hard problem. And I found this article from HPR rocketry magazine. Sorry, there's a spider right there in front of me, which is great, so you can go over here, dude. And these guys in America also amateur rocketry people like I was, they figured out you could buy a thing from Edmund Scientific, which was a little tiny magnetic disk with little magnetic poles around it. And you could put it on a little jewel bearing and spin it up to a really high speed with some coils. Now I discovered in the UK it was hard to get stuff from Edmund Scientific and I didn't know how to import this thing and where it came from and exactly how to get hold of it. So I started looking around for other sketchy alternatives to this and I came up with this. So you may, if you're a cyclist, recognise this. This is called a bottle dynamo and the idea is it rubs against your tyre and it makes electricity to run the lights on your bicycle. And it turns out that inside one of these, in the little bottle bit, there's actually a rotor and you can see there on the right hand side. That's the rotor there. It's about 30mm diameter and it's got four north poles and four south poles and it spins in a coil to generate electricity. So I thought, how? What if we turn this the other way round? And so I started to try some experiments. The next problem was how to actually get a low friction bearing and I discovered that the end of a propelling pencil was really good because it has a little bit of graphite sticking out so you have a graphite bearing which is self-lubricating. So this all sounds really sketchy because it is but amazingly it kind of works. So there's a diagram of it there. You can see that it has some coils around the outside to spin the dynamo disc up it sits on a little adjustable pivot and underneath are some infrared sensors which measure how far away the disc is from the sensors and by amplifying those differentially you can then figure out what angle it is. And you put this together you end up with this sketchy looking thing which is made out of hot melt glue and bolsterwood and epoxy resin all the sort of things you do when you're bodying things together when you're a student. But amazingly it actually works. So it's just spinning up there. The idea is it's got those little silver strips on the outside are detected by a little infrared detector on the side that impulses current through those red coils and that will then spin it up. And I think in a minute I'm going to pick that up and sort of move it around. So you can see an example here what's called gyroscopic rigidity so you can move the rocket around but the gyroscope stays still and that's how it allows you to measure the attitude of the rocket. There's one big disadvantage of this as you can know that guess which is because it's sitting on a pivot as soon as the rocket stops thrusting it jumps off the end of the pivot and it whizzes around inside the rocket which is not great for it but amazingly it kind of works. So this is just roughly what the inside of the rocket looks like. So it's pretty old school so there's a gyro it feeds a little microcontroller that operates two radio control servos which then gimbal the engine around and here's a film of it a film with a potato because potatoes are all we really had back in the late 1990s. So you can see it's sort of stable doesn't go very high parachute comes out doesn't really have time to open and that's it but it kind of worked. So oh there's another jellyfish gyro at number two then by this time the micro machine silicon sensors became available and these allow you to get a solid state gyroscope which doesn't need any moving parts and that really transformed everything we then ended up with this thing see if I can take it apart so there's an outer shell which was homemade out of some fiberglass wound around a drain pipe the little brackets on the side were actually for retro rockets that they're not there anymore because it turns out that it causes it to chase you across the ground. So that's the inside of the rocket you've got the two sensors on the back you can see they're all fognol to each other so they're 90 degrees it only measures the um just broken it this is all made out of model aircraft stuff and model boat stuff which is great because it means it's really easy to fix so the gyros on the back there go into a little microcontroller there which is a pick microcontroller and that operates two servos here and Eve I'm very lucky if I had a bit of tape here tape here to stop the engine falling out because it's only a push fit at the moment if I turn that on it may or may not work because I've done something to it and made it sad yep demo error sorry that worked perfectly mean to go but now it's stopped but basically the idea is when it tilts one way it'll move them out of the other way to correct demo effect in action this is what it looks like when it flies again sorry about the potato quality here is that going to play let's see I'm not sure that you're getting any sound on there sound on my laptop so you see that that one that performed a lot better thanks to the solid state gyros but thank you very much just gone out of my presentation so the problem is if you really want to make a rocket hover it's not enough just to control the the direction of the thrust you have to control the amount of thrust as well so you have to throttle the engine and this led on to a brief but abortive project called gyrock 3 this is a coaxial hybrid rocket engine with a a pintle injector that you can throttle it turns out though that you've then got a problem with thrust vectoring you need some sort of jet veins and that turned out to be a bit complicated and things were moving on and I wanted to try a bypass by this time I'd end up starting up a small company and had some other people around to help me who really wanted to join in the fun and see what we could make with bits that we had lying around the workshop so we came up with this thing which is gyrock 5 so it's a gimbled, bi-propellant, throttle ball motor and it runs on nitrous oxide which is laughing gas that's the oxidiser and isopropyl alcohol and those two burn together in a combustion chamber and produce hot gases out of the nozzle and that provides the thrust and it's got a thrust of about 30 I'm sorry 300 newtons which is about 30 kilos so that's the diagram you saw earlier on the control system diagram of the rocket when it was back when it was really, really simple and you only had to worry about the attitude of the rocket when you have to worry about the throttling it as well and trying to make sure that the IME doesn't drift you need a whole bunch more sensors and you have the challenge of putting that data together and use a thing called a Kalman filter and that's basically a device that is able to adjust the amount it trusts different sources of data depending on what it thinks the accuracy of that data is and it turns out by some very complicated maths which I'm absolutely not going to bore you with it turns out that's an optimal solution for dealing with this kind of problem where you've got lots of different sensors and some are good in a short time span and some are good in a long time span and it's a way of getting the best of all worlds what the actual diagram looks like so if you're going to mind this is the gyroch 1 and 2 diagram this is the diagram for gyroch 5 which is considerably more complicated so it has this Kalman filter that estimates its state at how fast is it, what angle is it and then it has a couple of different control loops for altitude and velocity and it's got similar control loops for the attitude which is its angle and that allows it to do something like this now this is just tethered we haven't let gyroch 5 off the tether yet because if we have to abort it because something goes wrong it's quite an expensive thing if it crashes so we have a tether here with a bungee on it and this is what it looks like it's supposed to be another video in there but that seems to have gone missing so I don't know whether you notice it drifted off to one side that's because it actually lost GPS lock we put a very tight constraint on how accurate the satellite lock needs to be in order to trust it and it decided it wasn't going to trust it so it starts to drift off and then when it reacquires lock it comes right back to the middle where it should be so I think let me just see if that's all I've got yeah sorry I don't have the other video so I've got to say thank you to all my colleagues at Airborne Engineering who've done all the really hard work their fellow nerds and makers like me who've also got a passion for rocketry they've been absolutely instrumental in making this project happen I really it's really an example of how you can make a start on something on your own but it gets to a certain level of complexity and it's just much much easier and more fun to have other people involved I also need to thank European Space Agency who have given us some money to actually start playing with something that was originally my hobby and so that's really gratifying and the UK Space Agency as well who dealt with all the paperwork for making that happen so thank you very much