 And so we have, next up, we're going to learn how to fall faster with my Curtis Rose. Thank you. Good morning everyone. So just a quick question is, who actually likes to jump out of planes at all? Anyone in this room likes to jump out of planes? Anyone else in the room who particularly likes falling? And I mean that doesn't mean necessarily off buildings, but maybe falling when you're a bit drunk in the pub, falling off walls, falling out of bed. Falling generally is considered bad. I mean it's generally not good for the body. It's not generally good for your lifespan if it's over a certain height. And falling out of planes is pretty exciting as long as you've got a parachute. However, sometimes people want you to fall and they want you to fall faster. Anyone know what terminal velocity is? Maximum speed of the human body, straight down. Give me an answer at the front. Closer to kilometers. Someone else. A little guy at the back. Yep, you. Bit lower. Anyone else? Give me an answer. Over. 140, close. 140 is pretty close. About 122, 123. Irrespective of how big you are, how long, how tall, a little bit affected by effectively what you're wearing, but fundamentally you can't fall faster than about 120 miles an hour. However, 120 miles an hour going into anything, doesn't matter whether it's water, concrete, etc., is probably going to kill you. If it doesn't kill you, it's certainly going to hurt. So sometimes you want to fall faster. And generally, most people who want to fall faster are either mad, they've already been committed, or they're TV presenters. And in this case, this is TV presenters. So last year I was approached by the BBC to ask me, could I use effectively my skills and I should carry out that. I'm a rocket propulsion engineer in my day job most of the time and I focus on 3D printing in my other time. And they said, we have got a TV presenter. We want to see if we can make him fall as fast as a peregrine falcon. A peregrine falcon dives at about 240 miles an hour. And this was for a CBBC series called Beyond Bionic. The presenter was a guy called, still is actually, he's not dead, fortunately, he's a guy called Andy Torbert, he's ex-bomb disposal, he's a bit mad, he likes to climb mountains and jump out of planes. Perfect candidate. And they wanted him to jump out of a plane, dive at the same speed as a peregrine falcon, exceed 240 miles an hour, and the crucial thing, be alive when he got to the bottom. Important from an insurance perspective. And the way they wanted to do this was they'd already effectively worked out what they wanted. They wanted a pair of big rocket engines to attach to him. Not probably because the rocket engines were the right things to use, but because the rocket engines look really cool. And they'll be great on TV. Great. So they've basically asked me, can you get a pair of rocket engines, jet turbines, something like that? Can you attach them to him? And I was like, yes, probably. Do you want him alive at the bottom? And they said, oh, absolutely, he needs to survive. So that was good for Andy and his family, and probably good for the insurance company. But the challenges of trying to do that is really hard. So if you can probably tell I'm wearing at the moment, these are our first iteration of how do you attach rocket engines to yourself? So I'm just going to come over here and stand up here, because I think that's probably easier. So if I do this, you can see, and I'm assuming I don't fall off because we're really spectacular, you can see I'm basically wearing metal boots, a little bit like medieval knights would wear. Excuse me, sir, if I just put my foot there. You can see they've got brackets coming out the side. And effectively what we were going to do were attach small gas turbines in the same sort that you use for radio-controlled aircraft to the sides. Now, the problem is it's not so much about having the gas turbine which is pushing you down, and you don't need that much thrust. You need something in the region of between 10 to 15 kilos of thrust per side. That's fairly easy to do with a small gas turbine. The problem is what happens when it goes wrong, and wrong is one of a few things. Wrong is catching on fire. Catching on fire is bad. Catching on fire with your engine on fire then catching your parachute on fire and then plummeting towards the ground from 12,000 feet is really bad. So you've got to do something about that. So the idea is how do you get rid of the engine? So in some way you effectively dump the engine. And the idea is effectively to be able to kick your leg up here, pull a pin, if you can pull the pin under centrifugal force, and the whole thing should go poaching. The reality is, as you just saw, I pulled the pin, and that was quite easy because I'm standing like that on one leg and I'm not spinning in circles, not with my parachute wrapped around me. In reality the insurance company said, it's a nice idea but you want to attach a gas turbine to a guy jumping out of a plane and then make him do a complicated maneuver where he has to pull a pin and you're expecting it all to go to plan. And we said, yeah, it probably will do, but maybe not every time. That wasn't good enough for the insurance company. So that option basically didn't work. So we then went on to a different system which was this wonderful bad boy. Now this is kind of the, in essence, the inglorious way of making something. This is very heavy. I'm going to pass it around, starting the front with you, sir. This system is basically mounted on your thigh. It's a better place than your foot because upon having something on your foot, when you kick your leg back like that with an engine running really fast, you tend to basically melt your feet, and that's again bad. So this system was designed to basically attach to your leg in such a way that you could then pull one of the complicated pins which you can see attached to it and the whole thing would push away. And again, the other caveat I have to throw in there is that you can't just ditch the engine. If you're ditching an engine which weighs maybe two to three kilos, plus fuel tank, plus ignition circuitry at 12,000 feet, unless you do something with that engine, chances are it's going to hit the ground. The chances of it hitting someone is fairly slim. However, you can't take into account the fact it's not going to hit anyone. So you have to have a power chute incorporated as well which further complicates the design. And you can probably tell, as we're going down this line, the guide jumping out the plane has a really heavy thing now attached to his waist, and that's not really ideal. It's also a jet engine, so it gets hot, it has to be canted away from the body, which is bad, and it gets more and more complicated. And then we've got another effect of something called counter-rotation. And counter-rotation is effectively the wake coming out of the engine swirling and turbines, they tend to spin in one direction. So the problem is you can end up with this counter-rotation of two engines with this swirl, this wake of hot air coming out from behind you which effectively twists you. So not only are you now going straight down in theory, you're also spinning in a circle. And again, if you're trying to deploy a power chute at the point the engine switches off, the probability of that working, your power chute not getting wrapped around you or wrapped around something else is very slim. So that's pretty bad. The biggest problem with a jet turbine though is basically the pilot said no, unsurprisingly. If I approached you and said, hey Mr. Pilot, we want to start two jet turbines in an aircraft which is inherently flammable at 15,000 feet with a lot more flammable things on board and a bunch of TV presenters. And we just want to hang out so he's sitting literally over the platform of the aircraft where you'd exit literally like this while I'm hanging down trying to turn these engines on because they don't start up instantaneously. Can you see anything going wrong with this? Pilot was like, mm-mm, it's not happening in my aircraft. You can go and do something else. So that kind of blew that up. Also, at the same time, the insurance company going. So you want to jump out the aircraft with a pair of jet engines attached to you. Is this to fly, to go faster? No, it's to fly fast going down. So can you say that again? Yes, going down. Actually, can we just pass you to a colleague of ours? Okay, that lesson over. Don't talk to insurance companies about strapping engines to yourself at least if you want to go up. So we then basically and this is where we got into freely printing. So the thing in which you're passing around currently, really, really heavy. This on the other hand, really, really light. So this is actually printed on an Ultimaker 2. Pretty small platform. Many of you probably have got a similar small 3D printer, fused deposition modeling, easy to utilize, etc. It's printed in nylon, it's lightweight, it's really strong. However, it's not for a turbine. Turbines get hot. This is for an electric ducted fan. Show of hands quickly, anyone doesn't know what an electric ducted fan is. Okay, anyone know what a Dyson vacuum cleaner is? Everyone, hopefully. Electric ducted fan, roughly is where Dyson works. High speed motor, inner shroud, forces air through are very high pressure. Bit like a jet engine, however, the exit velocity of the air coming out isn't in effectively the hundreds, if not thousands of kilometers an hour, it's typically more than 100. It's effectively a lower thrust, what we call a static thrust, but it still gives you effectively enough thrust to give you the lift that you need downward force that you want. You can put something like that into an engine. Lawrence, could you come up here, please? Actually, just walk to the front, that's probably a safer place for everybody. Go that way. Do you want to stand on the speaker? Yeah, you can stand on the speaker. This might be interesting. Lawrence is very kindly volunteered to demonstrate the system that we decided to use. While he does look a little bit like the Wizard of Oz, I can assure you he's not. What we fundamentally have is we have a pair of electro-ducted fans on either side, and these are held with 3D-printed holders, which incorporate everything. Nice, elegant design, combined as much as you can. Effectively, on each side, you've got a pair of batteries. Just around here, if you can see, there's an electric speed controller controlling the power out of a pair of lithium-ion batteries, and then they run basically to the ducted fans. The ducted fans have about 13 kgs of static thrust each. They're not technically off the shelf. I borrowed them from an ex-defence project, but I don't think they'll know about that, so it's fine. And this isn't been recorded or anything, so it's perfectly safe. And then this basically is linked to this really complicated harness, and this grab handle here. Lawrence, don't pull the grab handle. That definitely don't pull the grab handle. If he pulls the grab handle, what happens is you basically get pulled out, and the straps basically release, so you can dump the entire engine. And the key thing is it actually built inside the cavity and inside the plastic, there's effectively a parachute. And that parachute would normally be tied very loosely with a federally parachute thread to his trouser legs. So if he needs to dump them, they get in the way, etc. Paws a handle, engines fall away, parachutes get ripped out, and as they get ripped out, that thread breaks, and the worst that will happen is you'll get something equivalent to a fairly large conker hitting you on the head. I mean it's probably going to hurt a bit more than that, but it's not going to kill you. So these are powerful, and if you just give me one second, I'll connect them and demonstrate actually how powerful they are. Lawrence won't fly, if there's anyone lighter in the audience, you might fly, but my insurance doesn't cover that. So this is usually the bit when everything goes wrong because it has software that generally demonstrates that things don't work very well. Don't let that get sucked into those. So now Lawrence has a control box, and the way we did this actually in flight was with a pressor switch, which the pilot held in his mouth of the TV presenter effectively. So when he bit down effectively out of fear or happiness, the engine sped up. The first time I learned this is that TV presenters cannot be trusted. You cannot tell them don't put your fingers in the pointy holes at the top. So we lost the TV presenter when he, before we had FOD guards, tried to stick his fingers down here. That was bad. And then the other one was don't start it in the aircraft, and actually we learned the hard way as well, and the pilot learned the hard way is TV presenters don't know effectively how not to press buttons and things. So we end up with a pressor switch, which I basically had, a dead man switch, which meant that only after he exited the aircraft for all of our sakes could we actually make it live. So what happens if I press this? No Andy, I've told you don't press the button. Anyway, that was quite interesting. So Lawrence, I'm just going to back away from you, not that I don't trust anything, and your glasses are on aren't they? Excellent. I'm going to put my glasses on for safety because safety is really important. No one's at the front and there's nothing around you who's going to suck. He's not going to fly, it's just going to be very loud. Over to you Lawrence. That's good Lawrence! He's kind of loud, so I probably should give him Lawrence ear defense, but he'll be fine. I'm sure you'll all be fine as well, please no one assume me. But the thrust there is reasonably significant. A smaller member of the audience there, if you were perhaps somewhere between 20 to 25 kilos, you'd actually feel that thrust pushing you up and generating a lift force. The reality is if we turn Lawrence upside down, and if anyone wants to help me hold Lawrence upside down afterwards, I can show you how fast he'll be forcing to the floor. It works pretty well. I'm pretty much going to be running out of time, but just one of the things Lawrence, you just stay there Lawrence, we'll be the easiest. I've just passed a couple comments in terms of jet packs, so I guess some of you in the audience are thinking, hey, this looks really easy. I can get a bunch of EDFs and attach them to myself and I'll fly. You probably can fly. The big trade off is effectively the battery, weight, and the system weight versus thrust. So I've played around, and if you get about borrowed from some folks on the dark side, you can actually lift yourself, but only for about five feet above the ground for about 30 seconds. You probably could do some more interesting stuff as battery chemistry changes. The flip side is you can attach a bunch of jet packs to yourself, and a friend of mine called Richard Browning is doing exactly that. If you look up Rocketman on YouTube, you'll see him flying around. Now, the interesting thing about Richard is he's using some really powerful engines and there's a lot of thought and design going into how he's utilizing them. So again, if you think, hey, I'll just get a bunch of gas turbines and attach them to myself, I'd seriously basically stick with the ducted fans. The nice thing about ducted fans is they don't explode when it goes wrong. Gas turbines, you suck anything in where you call foreign object debris into the top here, and you basically now got a spinning hand grenade and they do go off with a bomb. So not only do you destroy a very expensive engine, you simultaneously effectively probably blow your leg off as well. Any questions, happy to date them subject to having any available time, which I'm told I do. And please come and take a look at Lawrence. We won't power up while people are close to full speed because I don't want to damage your hearing or at the same time seeing your digits get sucked into the top. Thank you very much. So any questions you'd ask if you wait for the microphone so everyone can hear? Hi, if Lawrence lay on a skateboard and you turned the fans on, what would happen? We'd have a really exciting episode of hacky racers, I think. So anyone got a skateboard? Very happy to try that. Did you measure what terminal velocity actually managed to achieve? Oh, absolutely, yes. Always light with detail. So we got Andy Torba up to 247 miles an hour straight down and he did manage to deploy his parachute and he did walk away. His comments actually were, that was so much fun, can we do it again? And I was thinking, yes, just if I'm long as I'm not involved. How much faster do you reckon it would be if you had been able to use the gas powered rockets rather than the fans? So the gas turbines were putting out 22 kg each as opposed to 13 of these. I reckon we would have probably got them close to 280, possibly 290. Interestingly, actually if you get a speed skydiver, they can typically get up to 260, 270. So I reckon we probably could with a little bit of tuning and slightly larger engines getting through the 300 mile an hour mark. The problem with that point is that we're going to have to start effectively engineering his upper body to handle that sort of velocity, which would be great. I just don't want to possibly be involved. Any other questions? Yeah, I was wondering about that. How can the, surely at 270 miles an hour the air pressure be pushed onto your head if he's going straight down? It was quite unpleasant, like any small deviation in his neck would like put an awful lot of strain on the spine. Yeah, I mean he's got a big neck. I mean he's an army. So he says a lot. Yes, it does absolutely, but typically what happens is they tend to dive not quite at a direct vertical dive. You tend to go at a very slight angle. The problem, the major challenge is actually trying to keep your orientation in free form. So you go at a slight angle and it's actually easier to correct that, particularly when you're compensating for counter rotation as well. So that reduces the pressure but absolutely, and the faster you go effectively the greater the strain is placed effectively on the head and the spine. So if we were going to want to get him up to really fast, I mean I'd love to get him up to basically break the sound barrier going down. 270 was fast enough. Exactly. We'd need to build him some sort of composite harness to support his upper body, otherwise he'd go splat. Okay, thank you. Great, and that's all the time we have. So let's give another round of applause.