EFFORTPOST [LONG][EFFORTPOST] Self taught engineer wants to make his own avionics system

Happy Memorial Day weekend dramatards! I recently stumbled upon some drama happenings within a few aviation related subreddits that has been going on for the past few days. To start off with, I'll list some aviation acronyms/terms that are going to be used in here that some of you may not be familiar with.

• CFI - Certified Flight Instructor. A pilot that can train other pilots

• LRU - Line Replaceable Unit. A box that interfaces with modern avionics systems and provides info. Can be stuff like speeds, altitudes, GPS, sensor information, etc.

• TSO - Technical Standard Order. Minimum performance standards required for parts, required by the Federal Aviation Administration in the US. Usually required for aircraft instruments and avionics.

• GA - General Aviation. In reference to small airplanes typically flown by private pilots (not airlines)

• DO-### - Documents provided by certifying agencies on how to certify certain components/systems

• PFD/MFD - Primary Flight and Multi-function Displays. The screens pilots look at in flight

• AHRS - Attitude and Heading Reference System. Describes the airplane's orientation in 3D space

• IFR - Instrument Flight Rules. Rules regarding flying through clouds

• CFR - Code of Federal Regulations

Our story here starts off with /u/Due_Ad_6457, a CFI who has made a post on /r/avionics 2 days ago about how he wants to learn and design his own avionics systems:

https://old.reddit.com/r/avionics/comments/13r0qkj/i_want_to_learn_how_to_design_and_build_avionics/

Basically asking where should i start (and dont say avionics technician school please). I can research on my own but was hoping any friendly community members had some advice. Fwiw I’m also interested in building it in rust and dont know much about fpga’s and asics, is an avionics system a type of asic?

I am not a true codecel but isn't Rust somewhat seen as a meme language? Anyways, some commenters begin asking questions or providing insight into the process. For simplicity, I have colored /u/Due_Ad_6457's comments as red.

So you want to design and build from the ground up avionics and autopilot computers and systems? From board level to programming? Is this for a hobby or a business, and what aviation experience do you have? There are a thousand and one things you'll need to know, and if you even want a little help you're gonna have to give a little more backstory. An autopilot is one of the most integrated and connected system in an aircrafts avionics system. I am intrigued about why you're asking, and what you currently know.

Certified flight instructor for 6 years and a self taught developer familiar with rust and low level programming, have never designed circuit boards but yes i would like to start from the ground up and am fascinated with building the next generation of GA avionics (integrate AI, possibly zkp’s as well to prove flight data with something like Cairo-lang), but i know systems programming goes even lower than i’m familiar with. I’d imagine its the same thing as building an ASIC from the ground up. Just a hobby… for now…

I'll be honest I see no purpose for the AI, but you do you. I'm glad you at least know your way around the cockpit, and as for making your own chips you really don't need to get that detailed. With your programming background a much easier thing to do would (and what all of the OEMs are doing) is basically a software driven autopilot. A Raspberry pi could easily handle the data IO for an autopilot and flight director. The hardest part would be interfacing to other systems.

In olden days an autopilot system consisted of an autopilot and flight director as two separate pieces of hardware. The flight director moved the command bars and told the autopilot where to go. The autopilot wnet where it was told and keept the aircraft from falling out of the sky.

Now everything is virtually one box. Take a look at the S-Tex 3100 system or the Garmin GFC. Both are one box systems that do it all. I can almost guarantee that there is a mini computer in there running a version of Linux (or similar) flying the aircraft.

I hope this helps give you an idea on where you could start designing your system. Remember at it's simplist an autopilot takes attitude, altitude, and heading data to keep the aircraft level, and then uses navigation data such as course, heading, and altitude deviation to guide the aircraft where you want it to go.

No purpose for the AI/AGI?! Lol in all seriousness I really appreciate your thought out responses. Very familiar with raspberry pi’s got a 3b+ at home probably a good place to start tinkering Something competitive to Garmin glass cockpits is what im envisioning, basically want to reverse engineer it and add the features i want

He wants to use AI? He thinks he's going to be competitive with Garmin, who are currently the kings of small airplane avionics? I get that it's a new and exciting technology but it still needs a lot of work before it's cut out for true engineering.

I know you said Rust, but… PX4 and PixHawk is an open source project for hardware and software for UAV autopilots, mostly written in c++. Depending on how comfortable you are with large software projects, and what your end goal is, it could be a way to start poking at the various parts of an autopilot system. At a high level, it’s quite different than manned aviation, but the underlying controls work is relatable. And, you can fly things, crash them, and not die, so that’s nice.

I’m team rewrite everything in rust, more secure, ergonomic, and programming languages have evolved from the 90’s so why not take what we’ve learned and use a better language? not super familiar with c++ but definitely sounds like a great OS project so i’ll take a look, appreciate the response sir

Rust will be difficult to safety certify. C and C++ are the staples for safety critical avionics applications.

I understand they’re the staple but rust as a language is more secure and doesnt let you shoot yourself in the foot like c++. It is clearly the new better way of doing embedded programming it just hasn’t caught on industry wide yet

This guy thinks he's going to join the industry with no degree and manage to convince them to change everything to Rust? So this finally gives us our true insight into him: he's . Some users are helpful to our mentally stunted pilot:

avionics technician school teaches you how to install and maintain. If you want to design and build, that would be engineering school. But that isn't the only path.

I would probably start with drones. I think there is plenty DIY in that realm

great point thank you sir

There are certainly a lot of good books on the topic of autopilots and their operation theory (some of which are textbooks for avionics courses) but really the theory isn't too exotic. You can consider an autopilot as a fancied up combination of if/then statements... IF the aircraft pitches up without input, THEN pitch the nose down until the previous static position is met. It does this with the use of sensors (gyros in older aircraft, AHRS units in newer ones) that measure motion and acceleration. IF it senses motion, THEN it sends either digital or analog signals to one or more servos to correct the position. Complex modes like NAV, APPR, IAS etc only act as a modified set of constants that are being provided to the autopilot computer.

If it were me, I'd start with one servo and one (either mechanical or digital) gyro and experiment. When the gyro gimbal tilts up in relation to the spinning rotor, then drive the servo in a set direction. Vice versa if the gyro moves in another direction. That's the basic theory behind it all, then you can start to construct layers of deeper theory and logic into the operation.

Good luck!!

I dont mind reading textbooks, I just don’t have any desire to pay someone to tell me to open a textbook and quiz me on it

I’m only focusing on AHRS, gyros are deprecated but if you think gyros are the best way to get started i’d consider.

Are you familiar with FFT fastest fourier transform and FFTW im guessing it uses something like this to optimize adjustments or am i talking nonsense?

Great response btw, really appreciate it

I think AHRS are certainly the best way to do things. Sorry for the miscommunication, I simply meant gyro as a general orientation device, not a full on physical air driven tool, those are ancient and probably hard to find!

I'm afraid that I'm not familiar with FFT or FFTW, but bear in mind that I'm a line and install technician, and when it starts getting to software I only load and understand, I don't build.

However, controversy arises when when people recommend degrees or think that what he wants to do seems crazy.

Aerospace engineering with computer science.

Sorry no, i’m a certified flight instructor thats also a self taught developer, i’ll pass on the degree but appreciate the reply

Well even if you manage to get the information needed for such a task without a degree, you'll never be able to certify or even manufacture anything without it.

Plus universities exist because they teach the high level stuff necessary for tasks like these in a robust and systematic way, creating professional experts. So not getting a degree is a sure way of remaining a hobbyist indefinitely.

Now if you just want to do it as a hobby, I'd start with demo programs within my capability and expand from there to progressively as I'd learn more things.

I can't stress enough that you need a degree in at least aeronautics, even though electrical engineering is more appropriate, if you have even the slightest thought of making something commercially viable.

I actually don’t think this is accurate, “without a degree, you’ll never be able to certify or even manufacture anything”, but feel free to prove me wrong with a source. there are regulations and a path for custom built avionics to get certified in aircrafts and it doesnt matter whether you have a degree or not, However I’d underestand if an FAA cert was required that i dont know about.

Imo a degree gives you a good foundation with outdated information, good enough to get your foot in the door working for someone else, but anyone engineering there own box needs focused attention and discipline to get it done, not necessarily a degree.

SOURCE? SOURCE? DO YOU HAVE A SOURCE?

He continues some more arguing in that thread, stating the following:

I gathered from this post that The majority of users in this subreddit are non programmers, either management guys or avionics technicians (and no uploading a program to a unit is not “programming”), nothing wrong with that but I’m looking for the actual builders and software engineers in this subreddit focused on avionics/Flight systems design who know how to code/engineer these systems and who know what Open Source Software is

This becomes a common defense of his later on, that none of the people he's arguing with are engineers and they don't know any better than him and if he just talked to an engineer they would know what he's talking about

First things first - an autopilot is a flight critical system. That means it will have to go through the highest absolute highest level of testing and approval. You're not building a USB charger or a map light.

You should start by piling up hundreds and hundreds of thousands of dollars, maybe a few million.

After that, you can contract an engineering company with experience and certifications to bring your napkin idea to a fully tested and TSO'd product. Then you can find someone dumb enough to have their aircraft ripped apart, get your box installed, wired up, tested and approved for installation in a single, specific model of aircraft (if you want more model approvals get your wallet out again to install your stuff in every model you want approved, plus testing, plus FAA approvals, labour, parts.)

I hope you realize the time it takes from idea to prototype to testing and certification takes years, thousands of hours of human time and more money then you'll ever earn in a lifetime to go to market. Garmin has deep pockets, thousands of engineers and enough feet in the door at the FAA to get their products approved.

Doing this on your own, with your attitude towards other people here in this thread, won't get anywhere except further in debt.

Who's going to buy your product over the other proven and approved products? I've seen countless products come to market and fail.

Good luck, or whatever. Your attitude stinks. Stay in the cockpit and let the real, certified engineers do the designing.

TL:DR - you don't have enough money to do this on your own. Someone with 18 years experience

I take it you’re not a certified engineer so you’re not really the kinda person im looking for advice from. You’re telling me I can “contact an engineering company”, i want to be the engineering company. “I can get someone stupid enough to rip apart there aircraft”? I’ve got 1 lined up already in the family hangar. I’m well aware that a box needs to get certified in every new plane added, would only like to certify it in a few, the most popular, which i’m quite familiar with as an instructor. Even with your backward way of saying things it was a pretty decent response for a boomer, but most of it was irrelevant and your advice is superficial. Edit: Lol sure as heck not taking your advice on designing critical flight systems seriously after seeing those dope weed posts on your profile 🍁😂

Dude is exactly on point, actually.

Go up a read my last response to my other coment. Easily 5 man years of experienced software development time (that's at least $1.5 million), $100,000+ environmental testing, and we haven't even accounted yet for hardware development, prototypes, test equipment, and other expenses.

Also 18 years experience in avionics software development.

And yes, your attitude sucks towards any comment that is trying to open your eyes to the reality of the situation.

You both sound like you’re in management roles tbh, not actual engineers but pls correct me if im wrong. You guys might know the steps in the certification process having “worked in the industry for 18 years” but I believe neither of you have actually engineered your own box, you just work for someone else who did. Plus software engineering & electrical engineering have come a long way in that time, change your attitudes and consider the fact that you might not know everything there is, share the info you feel like you have to offer and leave the petty insults out when you read a reply that you disagree with. l’ll take the information you shared in the other comment and leave you to your scrolling

Change your attitude and consider the fact that you know nothing about avionics development, and stop trying to insult everyone that actually does know something about it.

keyword something could’ve found out all that with an hour of research, don’t pretend like your advice is invaluable, its superficial. Thanks anyways

You're so petulant, it funny.

Let me know when you get that approval letter from the FAA.

l might no nothing about avionics development but i do know something about software development, which is what we’re talking about here. You realize you wouldn’t have a job if it weren’t for us. I also know a thing or 2 about flying and the FAA. Don’t be offended when i say your management experience isnt the same and that i’m taking your advice with a grain of salt.

Enter /u/drake_chance (yellow). He becomes the first of our CFI's biggest enemies.

"pass on the degree" this guy is a troll.

degree gives you nothing more than a good foundation with outdated information for 80-100grand of student loans lmao, i’ll stay discipled and do my own research thank you very much

Stay humble King

you’re the one calling me a troll from behind a screen lmao

[HIS ACTUAL NAME] - Owner of Avionics Works. I am not hiding, you are being un realistic asking for advice and then pooping on people who offer it.

Wasnt pooping on anybody, simply responding honestly. Got plenty of good advice from good samaritans, ignoring the trolls. Never heard of you or your startup so unless you work at garmin humble yourself anon and keep working on your startup in silence

The next day, our hero posts once again on /r/avionics with a new question:

https://old.reddit.com/r/avionics/comments/13sqhyc/can_you_build_on_top_certified_lrus/

The G1000 acts as a brain and pulls data from the LRU’s (line replaceable units) like your AHRS and ADS to name a few. Theres obviously some way these LRU’s communicate with the EFD and I’m curious if that API is available. Are these LRU’s black boxes or does anyone know if you can build on top of them?

Again, a few people give reasonable responses to OP:

Avionics LRUs don't really use APIs. They use standards/data protocols via buses i.e. ARINC 429, 1553, RS-232, RS-422, IEEE 488. I doubt you'll be able to find what software Garmin builds their equipment with unless you work for them. Though you'll be able to find some info on the standards/buy it. You definitely could build LRUs that integrate with the same protocols but, imo, it would not be worth the time or money to do so. Everything's basically been "figured out ", all MFDs/PFDs, HUDs/PDUs, flight control computers, radios, amplifiers, etc. despite having different manufacturers and slightly different operation and execution methods (different internals, procedures, etc.) all work pretty much the fricking same, pardon my language, in their respective categories. Cheers and good luck, curious to see other perspectives.

Great reply, I dont want to build the LRU’s i want to build the brain 🧠(EFD/MFD/PFD)it’d be easier if i could use LRU’s for data, because like you said, I’m sure they’ve been figured out/standardized by now and that they’re all basically the same.

I figure theres probably a license to access it. Not familiar with any of those lower level systems data protocols so I’ll do my dd thank you. Would you say these 5 protocols are the standard way the majority of LRU buses are built to communicate with the head. Do you think its possible to build your own bus using these data protocols to decode the relevant data? Would be cool to hack something together that does just that

EFDs/MFDs/PFDs, etc. are LRUs themselves. There are some open source systems out there iirc from companies like L3 & Top Aces but despite being open source, they seem to be quite tight-lipped (for obvious reasons imo). There could be some licenses or certs being offered but you'd probably have to contact the standard maker/owner itself. Sorry can't provide more info, not really on the dev or integration side of things, cheers & good luck!

EDIT: Didn't read everything. I mean, in theory, you could build your own bus if you had all of the wiring, couplers, tech data, etc., I do know there is some sort of converter out there, think its called MACC II. If I'm not mistaken, ARINC 429 & RS-232 are some of the most common, I just listed some of the ones I'm familiar with/of the top of my head. It really depends on the individual aircraft & equipment, but most of them are similar (work on hexadecimals/bits/words, etc.), I'm most familiar with 1553 as that's the main one in the test equipment, avionics, & aircraft that I work on.

God i hope all that changes in the next 5-10 years with Zero Knowledge proofs and blockchains. From what i’ve seen and know is coming, Software Engineers will be able to prove software in a way that allows for royalties to be paid by anyone building/iterating on top of the underlying system. Maybe this breaks at hardware components but who knows. Would love to see the rate of iteration increase across the industries.

Its sad to see the Aviation industry lag so far behind. Who the hells running that ship.

Our OP continues some discussion in that thread about the blockchain and Open Source and corporate greed and intellectual property and blah blah blah. He's clearly the hero that is going to fix software in the aviation industry.

Darn sounds like all this shit needs to be made open source from the ground up, where do i sign up.

FAA should inevitably be replaced by a DAO or at least something more decentralized in 10 years along with every other overpaid, underperforming, government agency in America. Provable permissionless, distributed democratic systems, with open data availability, are the future. fwiw.

what the frick does any of this mean

Anyways, our first villain returns in this post

I don't know the answer to this, but if it were possible, it would likely void the TSO/STC/certification, and therefor your C of A would no longer be in force.

that males perfect sense but im curious if you could build on top of these units. It’d be a cool idea to make these certified hardware interfaces open source and composable for faster iterations. it seems like its all a black box and everyone whos interested needs to start from scratch or maybe you need a license to access it? Appreciate the reply

Short answer, on a part 23 or car 3 certified airplane, not easily. On an experimental home built cert, knock yourself out.

Try not to die.

I’m aware of the regs

Certified flight instructor 6 years, you do realize planes don’t fall out of the sky without avionics right? You probably think they power the spark plugs too.

If you are a CFI, you probably should have the skillset to look up this information. Also, as a CFI, you should understand the danger of inducing spatial D from partial panel, especially if it isn't an immediately recognized failure mode.

But, my last line, wasn't meant as some kind of attack, Im just saying that there are dangers to what you are proposing. There are lots of good reasons for the TSOs and DOs to be as onerous as they are. I would be very interested in an open architecture for more things in aviation, but every company seems to think the only way to make money is to do everything the same way the last 10 companies that went bankrupt did.

Seriously, good luck, try not to die, this is an unforgiving business.

Yes and i also know you can’t fly IFR with an experimental aircraft in the first place so partial panel flying is irrelevant in the scenario. Also thats what backup gyros are for. I teach safe flying in light aircraft for a living and tinker in software engineering for fun and as a hobby. Appreciate the response.

Obviously i can look up the information on my own, wanted to ask the good citizens of reddit what they know first. Nothing wrong with that

Try reading the regs for required equipment (91.205) and show me where it says you can't fly IFR in an experimental. You are always asking stupid fricking questions here and then being aggressively peepeeish to the people that respond using the fact that you are supposedly a CFI as your justification.

Ok NAME, “Owner of Aircraft Avionics Work”, can’t even find your startups website online. Just your dumb face on Linkedin. You’re clearly not familiar with the regs like i am, your aircraft has to be certified ifr to fly in the clouds but i get u wouldnt know that with your skillset. Anyways, use common sense, who in there right mind would fly an experimental avionics unit in the clouds (if it were even allowed) without backup gyros, a safety pilot, and obviously it should be tested in vfr conditions under the hood first, your point is irrelevant, go troll someone else

Love pooping on guys like you in this subreddit who think they know better than the software and systems engineers or even pilots. this subreddit needs a cleans 🧼 go join technicians subreddit or the paper pushers subreddit, you’re clearly not an engineer/pilot you bum so stay in the shadows.

EDIT: down vote me all you want doesnt mean a thing unless you prove me wrong.

Fun fact: our CFI, clearly the most intelligent software engineer out there, is also the most intelligent CFI out there, as experimental aircraft can fly IFR provided they have the appropriate equipment!

At some point, someone who has been reading this makes a joke post mocking our dear CFI in /r/shittyaskflying, a shitposting subreddit for pilots and where I first stumble upon this goldmine of drama:

https://old.reddit.com/r/Shittyaskflying/comments/13sxiub/ill_make_my_own_lrus/

Don't even respond unless your a REAL engineer

Background: 25M bored with my 69th year as CFI, so I just taught myself electrical and computer engineering during my student's ground school.

I want to design my own LRU from the ground up. Problem is, I'm too smart to do the work myself. So....I'll just copy off of Garmin. I'll let ChatGPT sort out all of the legal details when I add a new blockchain, 5G, water-cooled EFD. That'll make all of you BOOMERS cry :,,,(

Mr. CFI is clearly pissed and responds to this post, and along enters our CFI's second villain, user /u/Mech_145 (green)

I see you pulled out the backup account for this post NAME loser cant stop thinking about me since i shit on him in /r/avionics and realizes he can’t prove any of my points wrong, dudes a fricking bum mad his startup is failing https://old.reddit.com/r/avionics/comments/13sqhyc/can_you_build_on_top_certified_lrus/

Man I read some of your comments on that post, you’re just as dense as the guy asking to get rid of pitot/static systems

Ok npc, lmk what you do for a living before you try to advise me or give me your opinion.

There’s a reason homeboy has been a CFI for 69 years

Theres a reason homeboy still works for someone maintaining legacy code XD

Edit: nvm homeboy just a mechanic.

You do realize that chatGPT and AI are just spitting out stuff that’s already been created/written just in different ways, so in a round about way it would still be legacy code

you realize you’re a mechanic that doesnt know shit about engineering? Go tighten a bolt or something and get out of my replies. Pretend like you know something about AI/AGI somewhere else

And a CFI doesn’t know shit about designing avionics systems, so lick my sweaty taint bud.

The ppl that actually use avionics in flight don’t know anything about designing avionics?? ever heard the saying know your customer? You look braindead.

I’m more of an engineer than you are you fat old man. You’re expendable.

So are you. And the end user is often very unaware of how things work, they know speed tape go up/down. Lights blink on/off, buttons click/click

I’m done talking to a mechanic pretending to be an engineer, be better.

I never pretended to be an engineer you dumbc*nt

clearly stated i didnt want to hear from your loser butt then.

Well it’s the internet and this isn’t your post so go back to your moms basement

This moron really fricking thinks because he uses avionics that he clearly knows everything about them

/u/Mech_145 and a few other users enter OP's original post and make fun of him there:

I would bet on it that actual engineers (esp those at Garmin/King/Avidyne/Honeywell) that see this will start inside jokes about this thread.

Sorry your life as a mechanic sucks “mech_145” and you feel the need to project your issues onto others. I’m looking for the engineers, just scroll past next time.

I have no issues, you just sound like a middle schooler.

25m, You have nothing to add to this post, channel this energy into turning your career around bum. Your kids wont ever have shit cuz daddy couldnt make something out of his life.

Says the kid still stuck as a CFI, what are your kids going to say when they find out daddy blew his chances to be a big bad airline captain and spent all their college funds on “developing” avionics

Lol i’ll go do that whenever i want, actually want to do more with my life than be a glorified bus driver or a mechanic like your loser butt

Those that cant build. Fix or Maintain. and thats why you get paid shit, literally a kid could do your job and you know it

This has now died down for the most part but CFI is still occassionally arguing with people throughout posts as of today. There are a few threads I did not include because it just would get too long. To finish this post off, every person arguing with him is correct on the difficulties and complexities of modern avionics systems. /u/Due_Ad_6457 is either an incredible troll or one of the most r-slurred pilots I have ever seen. I'm 99% confident it's the second option.