 Hi there welcome to my talk experimental aviation risks and award for the aerospace village Defcon 28 safe mode I decided to do this talk is a little bit lighter content than the Stuff I did last year, you know since those of us involved in security and verbally are also involved with risk I thought it'd be interesting to kind of apply the the risk model to some different perspectives since I'm Building my own aircraft. I'll talk about some of the things that I learned some of the decisions that you will have to undergo if you decide to actually get involved with building your own aircraft and Hopefully give you a new perspective on this particular segment of kind of DIY DIY and being a maker of building your own airplane So my again, my name is Patrick Kiley. I'm a member of the penetration testing team at Rapid 7 Previous I've done research last year on avionics security Had there's a talk that you can look up For last year's aviation village before it became this year's aerospace village where I talked about can bus and avionics I've also done other research in internet connected transportation platforms Have experienced in hardware hacking internet of things can bus quite a bit and I'm building my own airplane So here's kind of a quick overview of the agenda We're going to talk about the FAA regulations very lightly and that specifically this 51% rule Talk about plans and kits a little bit on quick builds as well Composite versus riveted aluminum construction, you know, just kind of the construction materials that you can choose to build your frame out of Little treat us on making changes to tested designs talk about engine selection avionics and then a little bit about the final steps after you've completed So the FAA defines the language for What is permitted if you're going to build your own airplane so certified aircraft have a ridiculous amount of Regulations they have to comply with for safety to ensure, you know consistency and everything else And it's one of the reasons that makes certified aircraft so expensive Experimental aircraft are not cheap by any means whatsoever, but they are a little bit more advantageous The FAA defines the rules and that federal aviation regulations 21.1 21 Section G and then they've got an advisory circulator That they did 20-27 where they clarify some additional stuff because of what some of the other manufacturers are starting to do The biggest thing is you need to have proof, you know, you need proof that you actually this was built by a Person and not a company. So this is basically be taking pictures of your work Keeping a blog keeping other records showing that you bought the components that you put them together something showing your progress The work can be started by someone else. You can actually buy somebody else's Amateur built kit and finish it yourself. Of course, you know caveat enter You don't know what their skill set is so you need to have someone who knows To kind of help review it and be able to actually examine the the work up till then and see if it's sound But and then you can also have help. That's how quick builds work. There are a lot of Programs where you can actually go to a factory and do most of the work and they then you just have the instructors there to guide you So you actually comply with that 50 point percent rule A repairman's certificate is a little bit different repairman's certificate basically allows you to work on it after it's done so For example, you can work on the engine more and wouldn't have to hire an Airframe and power plant mechanic if you can demonstrate you have the skill to do the work safely and successfully That's what a repairman's certificate is it's separate from the airworthiness certificate And it's a demonstration of the skill not a demonstration of the work and Experimental aircraft have restrictions that don't apply to commercial aircraft. You cannot use An experimental aircraft in a four-higher manner, but if you're just moving yourself and your family around you're not charging for it You're allowed to do that. You can Basically use it for a pleasure all pretty much within the limitations when you get the airworthiness certificate Your worthiness certificate is going to have its own set of limitations in it And it's going to be very clearly defined as to what what you're not allowed to do with it beyond that did the topic is Very complicated and I would just encourage you to do the research if you want to use an experimental aircraft in a particular manner there's going to be some Someone who has actually tried and done it and the answer is going to be out there for you in the on the internet So why would you want to choose an experimental aircraft? It can't be just because you want to fly if you want to fly you should just rent There are many things in life that you should rent and not own Aircraft is probably one of them But if you want to fly something that's a little bit more higher performance and you're an engineering nut and like to build stuff This might just be for you You have to be able to tolerate a certain amount of risk Building something that's normally done by professionals Automatically inherits a specific amount of risk and you have to be a willing to Analyze that see what it is and accept it It's going to be probably the most complicated thing you've ever done Because you're not just doing the airframe. You're doing the avionics. You're doing the engine It's a lot of different disciplines mixed in together But you can get a higher performance aircraft than you would be able to get for a specific dollar amount The image that I have here for the long easy there. It's a very high performing performing aircraft. It's also very reasonably priced It's a two-seater tandem One of my favorites is you'll kind of see later when you actually see that the kit that I chose to build It's a very solid choice for an experimental aircraft So how are you going to build it there are a few different ways you can go about this You can buy a set of plans. I actually have a set of plans here for my kit This is a set of cozy plans is a very thick bound large bound Manual that also comes with some very large format drawings so this is some drawings of the instrument panel using conventional gauges and then You know, that's just one section of two sections in the plans that that actually cover the whole thing The other thing that you can do and when you buy plans you actually just you source everything You're going to buy all the Components for example this one for it's going to be all the fiberglass all the epoxy all the individual metal components You're going to buy the engine the air front the avionics and you're going to build the airframe from scratch using just plants It's the least expensive option. It's also the most time-consuming the way kits work is you purchase the plans and Partially completed parts enough to qualify for the 51% rule They have some quick builds where a lot of the stuff is done for you But you still have to finish it and it greatly decreases the amount of time that you spend on it but You also increase the cost the picture. I have here is actually from Sun and Fun 2017. It's a velocity twin It's a gorgeous aircraft very high performing beautiful inside Canard design which is you can kind of see my preference towards those already And then there's another thing called, you know, builder assistance programs where you actually go to the manufacturer and They help you along the way, but ensure that you're actually doing enough to qualify for 51% of the work And then there's different materials So if you're going to build an aircraft if you want just something, you know low and slow or maybe a Small and single-seat aerobatic fabric overwood is perfectly valid The very first aircraft were made for me is that you might have some just aluminum tubes aluminum Spars and the rest of it's going to be wood the woods very easy to work with it also can be very lightweight And then you cover that with a doped fabric. It's a special type of fabric that's Coated in epoxy to make it very rigid Relatively easy compared to the other techniques Inexpensive this was just a gorgeous one that I saw at Sun and Fun I'm not even sure if it's fabric covered, but it's the type of aircraft that you'll see Probably the most popular style out there the one that has the most examples flying is riveted aluminum The vans RV line of aircraft are all riveted aluminum made with some composite components that you add here and there And that's how for the majority of aircraft history aircraft were built it was Aluminum that was all held together by rivets You have to be comfortable banging rivets working with blind rivets But it's very strong and light It was only recently that aircraft construction moved towards composite and But you'll still see a lot of riveted construction out there for existing airframes And now we get to my favorite composite. So this is what I chose fiberglass and epoxy or Carbon fiber and epoxy you can see a beautiful carbon fiber airfoil here What is composite so Really anytime you combine two materials and when those two materials are combined they form a stronger material you get a composite concrete Is a composite material because you have your aggregate your sand and your cement and you get concrete sometimes We you know with your reinforcing structures like rebar or other structures added to it, but it's still a composite So fiberglass by itself is not a composite fiberglass when it's bonded with epoxy is a composite a carbon fiber and Kevlar Not the bulletproof Kevlar, but an abrasion resistant Kevlar are also a couple of other Fabric materials that can be used in composite construction In fact a newer aircraft like the Dreamliners all composite construction 777X he's his composite wings And then conventionally fabricated fuselage So what I chose a but routine design. This is a little bit about those of my favorites He pioneered moldless composite construction. So it's it's a method of fabricating fiberglass parts without a mold You take a section of foam and I have an example right here So for this image, this is a section of that was actually removed from the aircraft in a building You can see you have your fiberglass and epoxy layer But beyond it you have sandwiched types of foam and they're held together with a micro micro bubbles mixed in with epoxy to bond both the Fiberglass to the first layer foam and then the second layer foam Together and what you do is on this other side, you're eventually going to get foam on this not for this this is a discard piece and Between the two by having This space separated by the two separate skins of fiberglass you get much stronger construction And you can basically take those shapes you can Lay them out and then you lay the fiberglass on top of it into its final design That was what a Bert Ruekhand Successfully did in his very easy and as long easy and he turned that into scaled composites and Now is going into space with that design He just did Voyager the aircraft that flew around the world without stopping And many of his other brilliant designs. He was a big advocate of the Carnard I think some of the the work has gone away from that But I'll kind of go into what a canard is in the next slide, but Most of his designs were can are based canards are very resistant to stalls you still have to follow weight and balance and you always have to Ensure that it's far enough forward so that the canard stalls first But a canard adds from lift instead of subtracting tracking from it as I'll kind of show you in the next image This is all from bold method In a canard designed aircraft the canard always must all first at the main wing stalls first Are you're going to enter into a situation called a deep stall? But it's a relatively easy thing to avoid as long as you follow weight and balance which you're supposed to do every time You fly anyway You'll never get into that situation so a traditional Conventionally designed aircraft you have your horizontal stabilizer that provides a vector of force Opposite that of the wing so it's providing in this image 250 pounds of negative lift that counteracts the 2,250 pounds of positive lift And then in neutral situation you have 2,000 pounds of weight You know in this particular configuration and the canard the idea is that it's more efficient Because both surfaces are providing a left both surfaces are providing a positive amount of lift to counteract the weight of the aircraft Again, all this composite picture of the skin. I just showed you Where you basically have a very thin layer of fiberglass with Embedded with epoxy It's actually a very friendly method to get into they both the aluminum and the Epoxy kits they have a what are called kind of like builders confidence kits. You're like I'm not going to spend $10,000 on a set of components just to see that this is really not for me So you can spend just a little bit and they'll give you some epoxy some Fiberglass and some foam and you do it you actually go through several steps to show that this is actually something that you're capable of In this other image. We actually have a canard style wing That's for a cozy. That's actually up on a jig before it has the The fiberglass applied to it So this is where I got into the selection for the plans that I eventually Chose so Bert Rutan designed the very easy and then he does design the long easy is a kind of Grunt up redesign of that long easy is a two-seat tandem aircraft These pictures are from Sun and Fun 2017 when I took them And then the picture you see here is that of an arrow canard that's still in partial primer Was really interested in this one because it's the design that I originally chose to go with and eventually actually licensed the set of a cozy plans as well Because I just wanted to make sure everything was covered. There was a some Disagreeing between that puffer and the guy that designed the arrow canard, which is a slightly roomier version of the cozy So just to avoid any possible issues In design, I wanted to have both set of plans because they're reasonably inexpensive and I could actually decide that you know if something didn't give me a clear image. I figured the other set of plans would so Here's a little blurb about making changes one of the biggest things I learned about From just looking in the forums talking to people is that any changes that you want to make I can have unintended consequences One of the the earliest things I learned is like, you know, why wouldn't you not? Take the fiberglass and use carbon fiber. It's reasonably cheap now Well, you're really not going to save a whole lot of weight But you are going to introduce completely different moments of elasticity You could actually add some Vibration elements that could cause something to shear and cause something to fail and and not anticipate it The other big line that I heard was basically, you know from Your aircrafts actually end up being lighter because you're not going to be able to afford any avionics to put in it for after all the money You spent on the carbon fiber, so you'll end up with a lighter aircraft that way It's a pretty Interesting when you actually dig into it and see that, you know, maybe not carbon fiber is the best choice for all our craft there are aircraft that were designed around carbon fiber the Berkut, which is a Fast and slick version of the long easy is a carbon fiber variant But it was designed from the ground up to have the amount of carbon fiber necessary that it has for it And then this is kind of a famous line from a plan So if you want to put something in your airplane first throw it up in the air that comes down doesn't belong in airplane The designer this was very minimalist and what he designed he wanted this aircraft to go without a battery He wanted to go without a starter using just prop start most people have chosen not to do that There are other issues and risk when you deal with hand cranking a prop You know all it takes is a little slip of the foot and now all of a sudden you're you know like the bad guy in Indiana Jones with a big fat spinning piece of metal Right in your face. So no, thank you I'll pay the weight penalty and deal with the starter but and then with glass panel cockpits You need to have a backup battery source You need to have a power source and if you're gonna have a starter you have to have a battery But it's it just goes to show that you know, you really need to be careful when you're actually considering making changes Is this gonna add weight? Is this gonna change the wing loading? Is this gonna significantly change the performance characteristics of the aircraft and Here's really a case study in this next example this the unfortunate Accident that took John van denver's life John Denver was flying along easy the NTSB actually found that the Probable cause of that accident was the designer decided to Take the fuel selector valve and instead of it being in front in the area where it was easily reachable by The pilot he relocated the fuel valve to be closer to the fuel source But what that actually did is when you actually have to select it You have to reach over your shoulder because of the you know Just you're kind of confined in so you actually have to do this maneuver to change the fuel valve And then when he was doing that they say he probably unintentionally put control pressure on the rudder Causing a loss of control causing him to fly into a Monterey Bay taking his life. So Just the thought the designer It's thought Relocated the fuel valve to make the fuel line shorter by having shorter fuel lines There could be less risk of a fuel leak But introduced other elements that were not necessarily reconsidered from the fuel valve being up front So in a long easy the fuel tanks are behind you the engine is behind you So the thought was let's put the the fuel selector behind you as well Maybe not the the best idea. It's a perfect example of the unintended consequences that you can have from actually Making changes and and why you really need to take a risk-based approach to any possible changes Then what the designers actually intended on this as our experimental aircraft is inherently a risky activity That was a little section about engine selection so when I was getting into this I was debating do I want to spend tens of thousands of dollars on a engine that was Effectively a 50 year old design and that's what they are all of the air-cooled Engines out there are really based on old old technology. Pardon me But they're designed for the purpose where they're used so But the thing I quickly learned is that the problem you run into with automotive conversions is And the Subaru is a big popular one because it's kind of the same horizontally flat plane opposed engine You have all the cooling issues you have to introduce some type of cooling system now You have a radio you have additional weight you have to put in an Reducing gearbox to slow the engine speed down to the appropriate speed for a propeller That adds additional weight adds additional complexity additional points of failure And then you have to deal with the fuel injection system fuel injection system that if you're using the automotive You may end up going to limpo mode and when you're in a car You can just pull over in an aircraft. You have to find a place to land immediately if you lose power It's it can introduce an element of danger that's unexpected and what they I discovered is they ended up not being cheaper They ended up being heavier more complicated more prone to more things that can go long and Because of all the changes you have to make there they end up not be any cheaper So we have can that leaves us with a convention line. There's yeah, okay You can do a turbine, but if you have that kind of money, you're gonna be getting a super high performance something anyway So conventional engines they are lightweight They're expensive for what you get. They are just look up IO 360 new and you'll see what I mean Not to mention things like an IO 540 or IO 540 turbo, you know turbo normalized or you know Some of the other fancier ones and imagine if you had an aircraft that two of these which you'd have to pay For to replace them in So there are experimental options what that basically means it hasn't gone through the exact same Certification process because the certification process itself is expensive, but yet you get the same quality so you can get an experimental version of these engines that have the same quality for a much more reasonable price than buying Something else that would that would be kind of in the certificate realm All right avionics one of my favorite subjects So when most of these designs came out all you had choices where we're like, you know your little round steam gauges as they call them I know you have your individual airspeed indicator your horizontal situation indicator, you know your your compass your turn and slip Vertical speed altimeter all of your you know attitude indicator all separate designs In a glass panel you combine all that with a moving map with GPS Other controls in a centralized point, but you're also introducing a central point of failure So you need to have some additional plans for that But glass panel Avionics are getting cheaper all the time there. There's some of my favorite things to mess with for those of you Study the previous research that I've done they I think they're safer. I think they provide you better situational awareness even in You know darkness you're going to be able to see the terrain in front of you if you have a more recent System so you're going to be able to see that because it's going to have the terrain database loaded into it You're going to see that there's an antenna tower loaded and I have to refer down to a sectional chart and manually Deconflict the aircraft is going to tell you that there's an issue coming up All your approach procedures are going to be built into a database within the avionics But what I feel that these need are some backup gauges now they have electronic backup gauges but Why not look for something that is reasonable and inexpensive and just use a couple of must have backup instruments as Your as your backups next to your your steam gauges. I think that's the best way to go All right, so little bourbon avionics cost And we're going to take the the Garmin g3x for example They make certified and experimental versions of the exact same display running the same firmware Just it's been blessed by the FAA and received certification approval 99.95 for just the display that's without any of the instruments without your your magnetometer without your airspeed sensors your various job, you know electronic gyros any of your engine instruments $10,000 just for the display whereas the exact same experimental display is $3,895 so My opinion best choice and avionics what I like The the ones that I've actually displayed on form. They're not mine. I've just done research on them But experimental glass with a few bad emergency backup steam gauges is a great combination Okay, so now that you've done this you've actually built your aircraft. What's the next step? You have to get a cert special airworthiness certificate. So what you do is you work with your? what's called a dar and you have it inspected and you get a Airworthiness certificate that tells you you have to fly for 25 to 40 hours and restricted away area away from population You have to fly out of a special airport. That's away from everyone else And you have to basically fly off the number of hours to show that this aircraft is is worthy to be operated On the same runways and areas that other aircraft operate and if you DIY this you effectively you are a test pilot But there are people that you can hire for this if you are not You know, this is a level of risk that you don't necessarily want to undertake There are people that you can hire that love to do this all the time that are very skilled Especially maybe for your particular airframe But effectively what you have to do is you have to build a test plan Same thing that test pilots would do so the first thing you do is you fire up the engine you test everything Then you taxi around in a little bit shut everything down inspect everything Then you undergo high-speed taxi testing where you actually get almost up to a flight speeds and then slow back down again and then you have your first flight and the biggest things I see in the Plans sections are when you do this you need to wear a parachute. I Guess that assumes you need to have taken skydiving classes But I guess any parachutes better than then any parachute even if you haven't been to the stuff is is better than not wearing one If you need to get out because you've gotten into an uncontrollable situation But this is kind of like probably one of the most risky areas of flight It's where a lot of the accidents happen Because something was tinkered with there were entertaining consequences and that's where disasters struck So thank you. I think we have some Q&A after this So we'll cut over to that and and please feel free. I look forward to your questions. Thank you for listening to my talk