 So I welcome you to the last talk. It's Yeah Not over yet. We will have one more interesting talk You will maybe hear BDL once again too because BDL is the one working together with Keith on this interesting project Keith is also a deviant Project member since probably several leaves. I don't know He's probably more known not for his Rocket work, but for his work on X X drivers Yep, so please go on. Thank you Well, we spent a lot of time this week talking about the delights of building the Debian distribution and packaging software and creating compilers and Shipping software free software all over the world to anybody who wants to use it this hour is a little diversion I'm going to spend the entire hour talking about using free software to Pursue one of my favorite activities flying rockets I'm going to tell you about some software that's in the archive that lets us do this fun hobby I'll show you some pictures and maybe encourage you to go out and build something yourself with Debian free software amateur rocketry has been around since the after after the Great War In the US there was a there was a large number of Children who used to fly little tiny model rockets. I know the hobby has been popular in Europe for as for nearly as long We like to separate Amateur rocketry and hobby rocketry Not really to we don't really like to separate them But I'm trying to talk about a hobby which is a little bigger than little model rockets that we fly at the park It's kind of a hobby rockets on steroids The rockets are generally made of composite construction. So carbon fiber fiberglass Oftentimes hand-machined aluminum Almost all of them fly with electronics in them. So we have computers flying on board the rockets We have computers down on the down on the ground Analyzing the flight data designing the rockets Oftentimes we make our own motors. So the motors are made of a Composite propellant to with ammonium perchlorate and hydrolated polybutadiene That mixed together and provide about as much thrust as you can get from a nice stable a nice stable tamper Impact-resistant fuel. It's the same fuel that powers the solid boosters on NASA's rockets like the space shuttle or Or the strap-on boosters on the Ariane spots Rockets as well amateur rocket tree involves building rockets that go pretty fast Sometimes in excess of three times the speed of sound Our rockets go fairly high up to about 30 kilometers in the last year or so and people are striving to get even higher this We have one place in the world where we have the ability to fly up to about 60 kilometers And I'm sure people are designing rockets right now to get that high And the rockets are often quite large this rocket. You can see from the previous frame If I can do this correctly it's about about a little over two meters long. It's about 15 centimeters in diameter and it weighed when it took off about 20 kilograms But people build larger rockets in excess of a 100 or 200 kilograms. Sometimes they're put up with cranes They get big As you might imagine, it's a lot more complicated to build the giant little rocket So we we like to do a little aerodynamic analysis In Debbie and there's a package called open rocket. You can install it from the archive today It's a rocket design and analysis system written by a master's student from Finland name of Sampo Niskanen He built a little Java program that let him design rockets. It's got the fluid dynamics necessary to Compute the drag on the airframe and the effects of Mach speed the air flowing over the fins and nose cone Why does it say about six active control? I don't know. Oh Right. Yeah, BDL actually told me there's about six people who are actively working on this project It's a giant piece of Java code And like many Java packages in the archive It arrives as a steaming pile of jar files that contain a bunch of upstream stuff a bunch of stuff from other Projects all mashed together in this giant pile Putting Java code into sensible shape for the Debbie and Debbie and project is kind of a pain and Open rocket is no exception. It were one or two releases back at this point And it's one of those projects that could use a little help making it clean the makings in the Debbie and world Another program that we use to design the rockets and build the rockets is called open SCAD. This is a really fun Script-based 3d modeling tool. It's not a you don't draw your object You you write code down to generate your objects, and I'll show you an example in a minute BDL and his son have a lot of CNC machines in their in their former home and in their new home They're getting more CNC machines And they're using this to generate the g-code which is necessary to to carve out your rock your rocket parts automatically And if you can have a computer controlling your milling machine outer to generate your rocket parts You can generate a lot more precise rocket parts a lot more reproducible rocket parts and a lot more rocket parts It's all good. Yeah, and I there's another slide here. It shows you why we needed so many rocket parts I mean and the final program I wanted to talk about in this section of the other talk was a program called motor sim When we talk about building our own motors that's actually designing the the geometry of the of the propellant and the nozzles and And and the hardware themselves in order to generate the thrust probe that you're interested in to generate to make the rocket Fly the way you want it to and there's actually a nice open-source program called motor sim that lets you type in the parameters of your motor And it will tell you how much thrust it will generate actually computes an estimated motor thrust curve Which is thrust over time We talked to the author of this code when we found it on the internet and said, you know We'd really like to be able to package this for Debbie and could you Put a license on it that would let us do that and he said sure what license should I pick and of course What license does one free software advocate always choose it's agreed to gpl the code and you know eventually beat it I will get around to you're releasing that and getting it into the archive Yeah, it's another Java program. There's there's a theme It seems that most people writing free software for the desktop that aren't Dedicated developers and other communities are using Java for the development and I support that I've write Java code myself It's definitely my favorite desktop Application development environment, although I don't really like Java the language. Here's an example of open rocket You can see up here. We can where's my cursor Here it is You can see up here You can add little components to your rocket and you've got a little hierarchical structure of the rocket then you've got a picture of the rocket and it tells you where the center of gravity is by estimating the mass of all the Components and the distance from the center of gravity. It tells you where the center of pressure is which tells you how much air Resistance is here and how much drag is up here and it estimates where the center of those are and as long as your center of Gravity is forward of your center of pressure then the rocket will go straight and so it's a bunch of aerodynamic analysis Other things it does is it knows the thrust curve for many promoters that you can purchase or you can even put your own thrust Curve in of course and it will estimate how fast the rocket will go and how high it will go and whether it will come apart Which is always good to know. Oh, by the way, your rocket is going to crash So with those tools we can build rockets. Here. We have a couple of fine examples On the left is a rocket that I call candy cane. It's a striped red striped rocket That's seen many in can incarnations I think that's the second set of fins and the original nose cone And the original ebay Yeah, it's kind of like, you know, it's you know So you have a rocket and you replace the fins and you replace the nose cone and you replace the electronics and you replace the motor Is it the same rocket or not? I've replaced pretty much every I have replaced every part of that rocket. Here's a rocket that BDL flew Last I would have been last spring at an event in Colorado. Where's my where's my curse? There it is Called an amram. It's a model of an American American military missile He had a lot of fun building that Unfortunately, we had some adventures which led us to a learning opportunity So the rocket went up to about what's about four kilometers up or so and Yeah, not so much with the parachutes and it came It came straight down and This is where how we found it embedded in the dirt. The rocket is actually oh about a foot into the ground on both pieces Now this rocket is interesting. It has the original surface to air missile had the forward fin the control surfaces It would steer the steer the missile around And this particular incarnation is just a model and so they're just stuck on But it turns out because there are fins on the rear part and fins on the front part They both came down together a parallel because usually if the front part doesn't have fins It kind of tumbles around and it would have just landed clunk on the ground have been pretty much okay But with fine fins, it was nicely stable the center of gravity was forward to the center of pressure The two pieces came down and yeah now we call that a learning opportunity It turns out that the electronics that we designed were faulty And yeah, so that's why we need a lot of rocket parts because this happens a lot The other program wanted to talk about was open SCAD This is the whole UI of the program. It's really simple on the left You see a program basically they're writing in the in this SCAD language. It's fairly C like it's pretty easy to understand And as you modify the program you hit f5 and it runs the program and generates the image I could show you a demo that I probably won't have time that I would like to And so once you generate this fit it to your CNC device Like your CNC router this is a CNC router in BDL's new Altus Metrum world headquarters, which is a 8 by 16 garage. I think it's like 3 meters by 3 meters by 5 meters That's the entire entire space that we have for the Altus Metro, but it's a router It's at this point. Just just cutting some test patterns But we expect to be using this to cut a lot of rocket parts in the coming months Yeah, okay in the coming days, let's be clear Yeah next weekend so we will actually know two weeks from today. We'll actually be heading on our way to Kansas In the US to to fly a lot of rockets and that'll be an amazing amount of fun Yeah, okay, so the other thing we do most of the time actually we spend most of our time building electronics BDL is an evil person It was about five years ago the BDL said, you know instead of buying these rocket electronics and letting other people have all the fun designing them and programming them We could build our own electronics. I know all design the electronics and you can write the software whoopee I'll write the software but great fun So BDL whipped out his favorite GEDA's suite of applications for building electronics G scheme is the schematic editor and PCB is the PCB layout tool. These are both applications in the repository, of course, of course GPL G scheme draws schematic diagrams like this So you just kind of plunk down your favorite circuit diagrams and wire them all up and then you push the button that generates a fake Schematic which puts all the components on top of each other and draws the wires in this big rats nest called a rat's nest And then you run this called PCB and it sucks that In that all the images of all your parts in and all the all the little rats nest wires And you put the parts where you want them by dragging and dropping them and paint little copper between them and you can create a PC board This is a PC board for a rocket flight computer. It has a Little CPU right here. The CPU is a TI chip con CC 1111 processor It's got a little flash part up here to store data about the flight The chip con part is actually a radio. So over here is our radio matching section and an antenna connector So actually connect an antenna up to that and it will send telemetry down telling us how the rocket site and Off the back end here It's got some FETs and some connectors here to connect up some explosive charges that control the deployment of parachutes pretty simple this board is What is it about? 8 tenths of an inch by an inch and a half which is like two two centimeters by four centimeters Something like that. It's pretty darn tiny And then of course if you want to be able to so I wanted to take you through the process so here we've designed a schematic we built a PC board and then We get the PC boards made and we get a little stencil made out of kept-on tape and solder paste onto the onto the board and Then we very carefully under the microscope stick all the parts onto the board by hand and then we stick them in an electric griddle Because that's how you make that's how you do electronics these days is with kitchen appliances So this is actually so the griddle hits up to about 210 degrees reflows the solder and you take the then you turn the griddle off and take the Board out and it's all ready to go after it cools off and then of course Somebody gets to program it. Here's an example of a finished board. This is an earlier earlier flight computer and here's our little Okay, I'm gonna go nuts with this cursor a little there's there's a little processor game with the radio matching circuit And there's a wire attached as in antenna and here's the FET that's doing the ejection charges Here's another board We spent a lot of time making boards. Oh come on Fastest display tool on the planet Listen, this one has that same little chip con part and this this one actually has Bluetooth on it So that's actually a commercial Bluetooth module with these little cast-related connectors on the side And so again, you just make a little footprint stick little solder on there clunk it down and cook it on the cook it in the skillet Because we have our own tools and because buying circuit boards turns out to be really cheap And because you do them in in the privacy of your very own home Even people like me can slowly learn how to make hardware by incrementally doing multiple So this design has nine parts on it and it took me four revisions of the PC board to get it to work I'm a little slow But each of these boards cost me a dollar So it cost me literally like, you know, 30 bucks to do four revisions of the circuit board including all the components So I could actually learn electronics in my home without spending a fortune. It's awesome These are us dimes this board weighs 1.9 grams or so. I have some examples up here. Oh Of course with the battery you have to have a power supply and the ginormous LED which is I think Four millimeters or so across It's huge So now that we've built all these electronics. What do we need to do? Ha ha we need to write the embedded software I thought this was gonna be fun and for the first couple years it was amazingly fun And then it just got to be tedious Not so tedious that I'm gonna stop but a less fun than building hardware, unfortunately So you can build apparently you can build an infinite amount of hardware because you know It just takes a couple of nights of laying out circuit boards and then ordering them then you wait for three weeks thinking about all the Mistakes you've made in your PC board and then the boards arriving you put them together. They don't work you rewire them and then you write software So in the in the Debian archive right now, there are two great embedded software development environments There's sdcc the embedded Compiler for 8-bit micros, but not the at-mail processor So for the venerable z80 the 8051 a bunch of pics and some other nasty 8-bit microcontrollers How many of you have programmed our delightful friends the 8-bit microcontrollers? Yeah, anybody remember the 8051 and how and how much fun that processor is not my favorite either Yeah, I know And the and the final one here is I've spent the week actually begging people to tell me how to get a GCC compiler for Modern 32-bit embedded processors into the archive for the little arm Cortex and zero and three parts I Don't know how to do that yet that today I spent two hours into to a listening boss trying to figure out how to do this and it's either Really hard really simple or really hard. I don't know which yet Yeah So someday I'll figure this out or maybe I'll get somebody else to figure it out I would love to know what the right answer is There are other people using the Cortex Cortex parts. They're really cheap and they're really powerful So a typical let me give you a scale of prices here a typical 8-bit microcontroller is about two bucks one to two bucks One to two euros a couple of Swiss francs. It's we're pretty complete the exchange flat these days The arm the arm processor that we're using on our fancy flight computer is four dollars and The arm process that we're using in our smaller one is a dollar and forty-eight cents. So one point forty-eight dollars Not a lot of money. This is for a computer Way more powerful than flew all of Apollo. Yeah now They cost a dollar and forty-eight cents and you put them on your you put them in your toaster So that the first compiler we played was with was the small devices see compiler the debugger Only the debugger that came with it it came with a compiler Library and a full-source lovely bugger and it's totally separate from GCC It's like a it's like a one or two person two or four of embedded development It works with the most ugly of CPUs. It works with the CPUs that GCC refuses to touch So ones that are so ugly and or a non-orthogonal and Incompatible with see that nobody would even consider using them for C development But the only other alternative is to write code in assembly, which is a lot worse So it's it's in of course it's in the debut archive The debugger that came with it only worked with the 8051 emulator So here you are writing 8051 microcontroller code and the debugger that you have only lets you debug the parts That don't talk about the hardware because it's all in running in this 8051 emulator But fortunately that debugger talked to the 8051 emulator over a little pipe And so I just created an 8051 emulator that talked directly to my hardware So I now I had a debugger talking to the 8051 emulator that was actually running 8051 code on my 8051 microcontroller So now I had a full-source level debugger Running on my source code for my 8-bit microcontroller This may be one of the few 8-bit microcontrollers with a plausible debugging environment I and All because I had the source code to this stuff and I could hack it up and make it do what I needed to do I wanted to talk about the GCC for the Cortex parts These are a little ARM processors, but they're not the ARM processors that you're probably familiar with. They're really tiny These parts have you know, they're in packages that are five millimeters square to ten millimeters square So they're really tiny little packages. They don't have very many pins They have very little memory the the big part that we're using has a hundred and twenty eight Kilobytes kilobytes not bytes kill flash memory We use the smaller the smaller ones that we're using has only 32 kilobytes They we don't they don't have a native operating system. So we had to write our own Lenaro is actually releasing tar balls for this particular target. They work great But that's a steaming pile of source code most of which we already have in the Debian archive I don't know how we're gonna integrate them into Debian. Here's a couple of suggestions So when you built your hardware and you got your software programmed you put them in your rocket And of course you don't put just one circuit board or one computer you put a couple connecting actors and This is from a project that BDL did last year Called yick stick 3 and the goal there was to actually do temperature measurements of the airframe in flight so the the board on the on the left here actually has 13 thermistors 12 or 13 thermistors connected to it that are scattered throughout one of the fins in the rocket to measure the Profile of temperatures in the fin in flight and the board on the on the right is actually Talking over the radio transmitting that information down to the ground while also storing it in flash We had to take the parts off the tops because there wasn't enough space for them So those two little parts sitting down to the GPS antenna and the beeper Those didn't fit because there was only about a centimeter or a less of space between Yeah, much less than a centimeter of space. We had to actually take the board apart to get it to fit Six and a half millimeters. Okay We've we started this plan of ours to build to build hardware for us to fly in our own rockets and We would start taking these fun flight computers off to rock people to say that's really cool Can we get one and it's like well, no, I'm making them in a skillet in my kitchen I'm not gonna make one for you too because I'd have to make one for everybody. I don't know how to do that It takes like an hour to make each board I'm in at another free software conference in Australia and New Zealand in Wellington, New Zealand We sat down and said we've got a lot of people wanting the software and this hardware What should we do about that and we decided I know we'll go into business together because business is awesome Plan Especially yeah, a small independent hardware business are simple don't lose too much money Well that there is a saying in the rocketry world, you know how you make a million dollars and in a rocketry business Start with two million. Yeah. Yeah, exactly Yeah, it's awesome But of course in the in the rocketry community very few rocketeer the rocketeers are split into two camps There's the redneck rocketeers and the geek rocketeers You can tell them apart at rocket launches We all look the same, but the redneck rocketeers when the rocket is destroyed. They're interested in getting the motorcase back to her When the geeks rocket is destroyed he doesn't care about the motorcase very much It's kind of nice, but the geek wants the data back It's kind of an interesting everybody has a good time blowing stuff up making loud noises Rednecks want the parts back the geeks don't care about the airframe. They just want the data So we built the system that would give us the data back even if the rocket blew up that was our telemetry system Some of our some of our fellow rocketeers. They don't run Debian At least not yet. We've actually converted three or four of our friendly rocketeers from running windows. It's pretty awesome So it's nice to know that even rednecks can be trained But not all of them on Debian yet So we need a solution for people that are running windows that are running Macintoshes or that have Android devices Fortunately Debian provides solutions for those two. Isn't that awesome? So if you want to build software for Windows, you don't need a Windows box You could build Windows software on your Debian machine. You can write the code. You can compile the code You can create a package You can do a whole installation script that puts up the licenses and have the clicky little boxes to say what parts you wanted You can put together UI on Windows if you want to all the wife just wrote Java code because I didn't want to write Windows UI code So the GCC Ming GW compiler lets you build Windows code native Windows code on your Debian system And then there's the ensys installer system that lets you build a Windows native installer To package up all your software for Windows on the Macintosh We don't we don't we aren't able to compile Macintosh binaries yet Although I don't really know why I couldn't couldn't constructed GCC back end to do that But at least I can construct a package for the Macintosh So because I'm using Java for Macintosh UI I can build that and test it on Linux and then I can use the gen ISO image program in the Debian archive to construct a CD image that the Macintosh will recognize and load a load the application from it's a nice packaging trick For the Macintosh and of course the Android's native development environment is desktop Linux So we can get all the Android development tools you could ever want So we can build software on Debian for Windows Macintosh Linux, of course and Android So I never have to open up a Windows box to do this work I never have to open up a Macintosh Except when I need to build some Macintosh Pacific C code and I have to deal with the eclipse disaster on Windows either It's very nice Here's our little here's our little Android application It's a native Android application built on Debian. It uses the common code So because my desktop application is written in Java and my Android application is written in Java I can actually share the library code between the two So I actually have a shared library a shared jar file that contains all of the complicated computations in in the desktop stuff to convert sensor measurements into real numbers and Compute GPS distances and that kind of stuff and I actually build it now shipped on both Android and Linux So if you're interested in doing applications at port from Windows Macintosh Linux all the way to Android Java is a pretty nice application Development environment of course this application is available in the Google Play Store Or you could just download the source code from our machines and build it yourself Well, we decided to start a small business and every small business needs a whole bunch of software to run their business these days The two things that we're doing at Debian right now for our business are accounting to actually run our books and to build a web store If you're building if you're building physical objects, you need them It's not like software. You can't just give the hardware away as much as as much as we would like to So we're selling the stuff through a web store For accounting we tried we started out with GNU cache and in fact our books are currently in GNU cache It's a pretty nice entry to introduction to double entry bookkeeping It mystified me for a long time. I have to admit BDL told me a couple of pretty simple pointers It led me to kind of figure it out although I still have adventures and have to relearn half of it every time I open up the UI It's certainly a lot of certainly a straightforward as straightforward as double entry bookkeeping can ever be apparently The problem is that it's very gooey based the data files are big binary blobs and We like to have traceable entries that we can track our our cash transactions and our bookkeeping in a nice Ascii text format so that when you commit them in git because everything lives in git You can actually see differences that make sense. So we're switching over to this command line Accounting program called ledger CLI That uses file that you edit with a text editor and then you basically compile the text file into a set of books for your business The web store front. I don't think either of these is available in Debian It would be look Yeah, exactly. So these are a couple of PHP disasters that we run on the standard Yeah, oh my god, who likes PHP? Whoever thought this was a good idea Any case we started out building our store with a system called open cart It was fairly easy to use and it had constructed store. So all you had to do is dump your parts into it And dump your your products into it and you could see them immediately It was easy to get stuff up and running. It had kind of a primitive Google checkout integration The problem is the and it works we're currently using this We were using this until a couple of months ago and then the server had a problem The problem with open cart was that getting an order out of the system and getting the shipping label printed and getting the order Process through Google checkout took a lot of clicking And a lot of interaction by by us and we didn't really like that and the store itself was really hard to make it work The way we wanted to so it's switching over to a more complicated system That's actually used by a lot a fair number of major retailers online retailers called magento Which is huge and amazingly configurable and when it comes up you have an empty web page and it's like now What do I do you start typing a bunch of PHP code apparently to get your products into the web page? It's very configurable and it's enormous and difficult to understand But the payoffs here are that the payment and shipping stuff is way better integrated So when the customer clicks through to find out how much shipping costs It actually has a shipping computer that goes and talks to UPS or FedEx so the post office and figures out how much it's Going to cost to ship it to them and the order handling is nicely automated so that when the payment happens it Way fewer manual steps. It's going to be nice Neither of these is packaged for Debian. So this would be an opportunity What's it about four years ago we were in New York Debian 10 and this is Debian 14 15 13 whatever in New York So many debcons sold After debcon in New York City BDL and I actually arranged an expedition About 150 miles away from New York City. They were having a rocket launch the weekend after debcon So we took a collection of the debcon for 10 days up there and introduced them to the fine sport of model rocketry. I know It's the and and we did provide free rockets didn't we BDL and free motors free transportation Yeah, okay That's bad They're bad bad people and here's here's a couple of us enjoying the rocket launch up there. We had a good time I was more rockets. Oh Brought it. I brought a fairly large. It was about a meter long not a very big rocket And you had sharp stick that's right So we had an awfully good time the lovely part about the New York rocket experience was that it was done on a sod farm where they're actually selling Selling turf to be cut rolled up and brought to suburban homes for to put out there So before the saw before the turf is cut we actually get to fly rockets on it So it's like flying on a giant lawn It's awesome. It's like oh my rocket is over there on the grass. Oh, this is going to be very hard to walk to I don't know if you saw that when you saw the first slides here here go back and I'll show you This is where I fly rockets out in eastern Oregon. It the place is covered with sagebrush, which is a hearty drought tolerant species With sharp pokey branches and it entirely covers the place It also has a species of rabbit that is apparently capable of taking your rocket and hiding it under the sage bush within minutes of the flight I Don't know where we grow those Rob. So out in Oregon if this is this rocket's like two and a half meters long 15 centimeters in diameter if it lands between you have to get to within 20 or 30 feet of it before you can see it Because the sage bushes, it's about you know a meter tall just tall enough to cover everything It doesn't look like anything when you're looking out over it looks, you know like a nice flat Nice flat feature this terrain, but in fact it's covered with bushes so Flying that is kind of it flying in that environment. It's kind of an adventure So flying out in in New York was kind of fun because it was a giant lawn and We really had a great time with the debbie and developers and other other debconf attendees flying out there and With that I think that's the end of my presentation. This is BDL son who a real airframe It has kind of a funny shape It's got a lot of fins on it and a very round nose It turns out in order to make this airframe stable you have to put like a kilogram of metal in the nose Otherwise, it's not stable almost two kilograms. Yeah, so that thing is really it's like a little, you know, it's a flying brick Which which gives extra, you know an extra challenge because it's really heavy so you have to be very careful about recovery and deployment systems and Robert actually flew it successfully for his junior NAR levels junior. No his Tripoli Tripoli research Tripoli Certification so he can fly high-power rockets with us And had a great old time you can see he let they also live in a desert right next to his knee is a cactus bush And so when you're walking around that area if you happen to brush up against one of those big pieces that break off and bite you Yeah, we fly rockets and hostile hostile territory in any case with that That's my story of debbie and software for flying rockets. We have about 10 minutes We have questions or we can head out for the barbecue So thanks Keith. There's a question. I actually have two questions. I want to ask you First question is is there any risk of you actually hitting an airplane while you're shooting a rocket up? That's a really good question because these rockets go as I said as I said they'll go 30 kilometers Which is well past the altitude of most 8 most airplanes We actually work with our local civil aviation authorities to ensure that while we're flying rockets in this area We have the airspace off out of the aviation maps And in fact out in eastern, Oregon when we're flying rockets out there if an airplane goes near our area You actually see it come to the edge of our area and go around Keep going Yeah, we work very closely We also have very stringent rules so that if you see an airplane in the sky and the sky is big because there's nothing there You don't you don't you don't launch the rocket the rocket is typically ascending for less than a minute and so an Airplane at the horizon is going to be 10 or 15 minutes away So the so you're clear for the entire duration of the flight even if somebody doesn't read Notifications to know not to fly airplanes in that area. So we're very careful about airplanes, but the sky is also really big Airplanes are really small. These are unguided rockets So even if we tried to shoot a rocket at an airplane the chances of us hitting it are infinitesimally small so And of course most of our rockets except that one Are don't have a lot of mass to them and actually hitting an airplane with them would be would would terrify the pilot But probably be harmless, although I wouldn't want to be in an airplane hit by that chunk of lead Yeah, my second question is about the the radio interface you you have on your rocket because Apparently you you actually want to relay the data back to earth while the the rocket is still in the air Oh, yeah, so which radio standard are you using? So actually yeah, I didn't talk about anything about what we actually built But the the products that we built are called telemetrum and we use amateur radio Frequencies in this particular case the 400 400 megahertz band and we constructed a custom digital telemetry system that uses 38.4 kilobaud Gaussian shaped frequency FM modulation on a 70 centimeter carrier and on top of that we put We put Constraint for half-rate convolution encoding of the data for and for good error recovery And so we're just doing a basically a custom digital modulation of the data at 38 kilobaud Which gives us a 19 kilobaud data link So we're actually able to get a lot of data down while the rockets in flight the radio runs only 10 milliwatts and Yet we're able to get ranges upwards of you know 30 or 40 quite reliably because of the encoding scheme Other it's the chip con part that we used there with the horrible 8051 microcontroller in it We chose that because it had a digital radio part capable of doing this modulation scheme That was really the genesis of our idea of how to build a small Rocket computer that could also send the data down now another important part of that the flight computer that we usually use It has a GPS receiver in it. So the rocket not only tells you what's going on It also tells you where it is Which is important when it falls in the bushes and you haven't and the rabbits hide the hide the important parts of it so it actually so you actually So a telephone I have an indication of where I am and an indication of where it last heard from the rocket And when you put those two dots together on the screen, you're usually within sight of the rocket So it's it's it used to be finding your rocket after you launched It was a huge hunt and all people had you know great stories about you know walking for days and days to try to locate their rocket and Unfortunately, we've kind of kind of removed that section of fun from fun from the hobby By making it so that you just walk to your rocket when it's on the ground But that's what the telemetry is for the telemetry tells you Things like what the temperature is within the rocket to how high the rocket is with bear It tells you whether the battery voltage is okay. It tells you if the ejection charges have fired all kinds of stuff like that That's great fun We have so our usual flight computer has an accelerometer to tell you what the motor is doing to your rocket a Barometric altimeter to tell you how high it is our more advanced ones have three axis of Gyroscopic information to tell you how tilted the rocket is And three axis of accelerometer to actually be able to compute the the flight path of the rocket And all that's recorded on in flash on the rocket flight computer and a portion of it the amount that we have bandwidth for is transmitted with a telemetry stream Lots of fun. All this stuff is oddly free software under the GPL The designs are licensed under the Tapper open hardware license Which is a deep GPL ish license for hardware and all of those designs and all the software is available at altosmetrum.org Other questions this afternoon how long before you go to space That's actually an interesting question XKCD had a really good a really good comic on this a couple of days ago I suggest you go look at it Space is by definition a hundred kilometers up and we already have people getting to 30 kilometers So you're thinking it's only three times as far. How hard can that be? Well, it turns out getting to space is actually very plausible Probably two stages of a fairly fairly a well-designed rocket could probably reach a hundred kilometers and in in height The big problem with space is staying in space Our rockets at 30 kilometers that rocket was going, you know, zero kilometers an hour relative to the earth So it just went straight up and came straight down In order to stay in space you have to be going Mach 15 at a hundred kilometers up So you have to have it you have to get enough fuel up to that spot to be able to accelerate yourself to the 15 times the speed of sound before you'll stay in space So it turns out getting to space is very plausible With our technologies the the prospects of staying in space without a lot more money and a lot bigger Rockets is pretty is pretty weak. That's a good question So I say XKCD had a pretty good had a pretty good comic on this a couple of days ago. You might go look at Yeah, probably Other question. Oh, yeah. Oh, that's right for those of you who are going to be a debconf next year There's a rocket launch Well, I don't know which weekend debconf that's gonna be scheduled that because the week that it's currently scheduled is one that has a rocket launch Conflict for a couple of us Yeah, but in any case if you do come to debconf next year in Oregon I can promise you that if it's scheduled at a time that I can attend we can take you out for a big rocket launch in Eastern Oregon Yeah, we have we have access every weekend to to the Oregon desert. So if you want to build rockets May rock it buff We've done that a couple of times and this is probably the closest we're ever gonna get to a home field for either either BDLR Or I because it is my home field Other questions. Yes So what's the average safety radius you need for flying such rockets? I guess it's difficult to find a place where you can safely fly rockets in densely inhabited areas Yes, it indeed it is So what we what the what we do is we work with a civilian civilian fire authorities and the civilian aviation Authorities to try to find a place. It's safe to fly rockets. We have to be far enough from inhabited buildings So it's land in the building. We don't kill anybody Which means we don't want to land on buildings. We have to be far enough from Busy roads so that a rocket lands in the middle of the so we don't want the rocket to land in the middle of a busy freeway We have to be we don't like to fly near trees Because of the rocket lands in trees. They're very difficult to get down Fortunately in the Western US. It's a desert and nobody lives there It's really hard when I come to Europe It's really hard for me. I can easily understand how difficult it is for you to grasp But I go to a place that I fly rockets where they're within 50 miles so imagine a place in Europe with a 70 70 kilometer radius where there are no inhabitants at all There are no no, you know, there's no shacks. There's no cows. There's just sage bush so and A lot yeah the evil rabbits Okay, so it is worth mentioning though that there's actually a quite active Set of high power and amateur rocketry groups in Europe There is in fact a Tripoli Pretherland and they have launches approximately once a month somewhere in the country and their big annual event apparently Is a four-day weekend in October about 15 kilometers the other side of new Chateau So we're actually quite close to where the big Swiss launch happens every year, but we're just here at the wrong time Again because we designed the rockets to go straight up and come straight back down The general rule of thumb is if you want to go up, you know If you want to go three kilometers up you need a space that has one and a half kilometers of radius clear of any buildings That's not a huge space, right? You can a mad farm big enough to do that in and there are apparently farms just a few kilometers away Near new Chateau where it's so we can fly rockets and of course the smaller the field you just build rockets It don't goes high and that's also fun Most of my most of my rocketry is done within a cut within a kilometer So over the ground and the rockets usually then within a couple hundred meters of where I launch them And even my launches most of them are in the two to three kilometer altitude range that you know the the really high launches we do in places like the Black Rock Desert in Nevada or of the launch that Keith and I like to go out to at the end of August every year is in the middle of wheat fields and after they Harvest the wheat and plow the fields It's just plowed dirt that's flat as far as you can see in every direction And they have a waiver to 50,000 feet above ground and 12 nautical miles radius So it's a really really big Area to fly really big rockets Well, I want to thank you very