The Great Ongoing Aviation Thread (general and other)

The two cooperating airplanes are separated in space is such a way that any attack on one by necessity exposes the attacker to simultaneous counterattack by the other.

If you’re thinking of the wingman as something like the Thunderbirds, where the two airplanes are 20 feet apart you’re thinking wrong. In typical jet combat, the two fighters operate line abreast about a mile apart. Each is usg radar and eyeballs to see what’s out front, plus eyeballs to see what’s straight up or down, and to the sides and aft. With particular attention across the formation and rearwards to identify anyone sneaking up on your wingmate.

And again, all this was designed around forward firing machine guns, later cannon, or forward-firing short-range rear-aspect-only air to air missiles. It begins to contain an air of artificiality in the face of all-aspect IR missiles, radar-guided long range missiles, etc. But the lateral spread formation is still helpful against those threats. Doubly so if you add a half-mile or so of vertical separation.


One of the things the Top Gun movies got horribly wrong (for legit movie-making reasons) is the scale of aerial combat. The enemy isn’t 100 feet away. He’s 1, 2, or 15 miles away. You’re doing battle with a flyspeck somewhere in the sky. By the time it’s close enough that it’s big enough to see what kind it is, you’re already real deep in the fight at daggers drawn.

they have a nasty habit of turning 360ies …

Interesting new company in general aviation–Airhart:
https://www.airhartaero.com/

There is a long intro posted to Hacker News, which I’ll put in a summary box here. I don’t think there’s any copyright issue since it was posted to another public forum site and clearly the author wouldn’t mind it being spread to other sites:

Summary

Hey Hacker News! I’m Nikita, founder of Airhart Aeronautics (https://www.airhartaero.com/). We are building an airplane for people who don’t fly airplanes. The goal is to make flying as easy as driving a car—while maintaining a high bar for safety. Here’s a video that shows a bit of our hardware and quite a bit of our software: https://youtu.be/PGJUGUceu8A

In the US, trips that are 50-300 miles are almost all done by car because that distance is too short for commercial airlines and too far for public transportation. Thanks to the Wright Brothers we’ve had aerial transport for over 100 years. The US has over 19,000 airports, and large commercial airplane technology has developed to the point that the planes practically fly themselves. If we already have the infrastructure and the technology, why isn’t everyone flying planes?

The problem is that small airplane technology hasn’t innovated and is stuck in the past. Flying a small airplane is complicated, mentally taxing, and dangerous—about 28x more dangerous than driving a car. Outdated airplanes, coupled with outdated flight controls, lead to regular accidents, often due to some form of loss of control. The planes are expensive and margins are small. There is no incentive to innovate within the current market, so we are looking at the new, untapped market of those who don’t think about flying as an option today and making it an option.

I first came across this when I learned to fly in 2020. I was learning in a “modern” GA airplane but was immediately struck by the fact that an airplane built in 2018 did not have an engine computer and there was a manual level to control the fuel/air mixture ratio. Starting it on a hot day was like starting a stubborn lawn mower. On top of that, my instructor was telling me all the various ways I could kill myself if I’m not running at 100% concentration for hours on end. This just didn’t sit right with me.

At the time I was working at SpaceX as an avionics engineer, leading the development of the avionics for the fairing recovery program. I also built autonomous aircraft when I was a student at Cornell, where I got a degree in electrical and computer engineering. It was clear to me that the core problem is that airplanes are too unsafe and too complicated to operate which is keeping too many people out of aviation. So, I decided to leave SpaceX and was joined by my long-time friend Brendan (he was a software engineer at Apple at the time; we built autonomous aircraft together at Cornell) to start Airhart to tackle this problem and make flying safer and more accessible.

We are developing a full hardware and software package to change how people fly airplanes. It’s a fly-by-wire control system, meaning instead of mechanical linkages between the pilot’s control stick and the control surfaces, it’s a joystick that sends digital commands to a computer that then moves the control surfaces accordingly with servo actuators. We’re developing all of the hardware ourselves: the computers, the sensors, the actuators–and all of the software that actually does the control. But it’s not just fly-by-wire. On top of it, we are implementing a simplified control scheme that reduces flying the airplane to just one action to perform one maneuver.

For readers who aren’t pilots: all flying is basically coordinating the aircraft pitch, roll, yaw, and throttle to coordinate actions. Something as simple as a level turn to the right means you have to 1) roll the airplane, 2) use your feet on the rudder pedals to keep the turn coordinated, 3) pull back to increase your lift since you are now losing lift in a bank, 4) monitor your airspeed (especially if at slow speeds when coming in to land), 5) monitor your altitude as you’re adjusting your lift in (3), 6) monitor your turn coordination as you adjust it in (2). You are now established in a turn. To return to flying straight and level do those in reverse. And while doing all this, you need to be navigating through complex airpaces and talking to air traffic control over 1940s radio technology. All this together makes it very hard to fly and very easy for a pilot (especially a new pilot) to lose control of the airplane, which is still the leading cause of fatalities in general aviation.

With Airhart Assist (that’s what we call our system), you just push a control stick to the right and the flight computers do all those steps to put you into a coordinated level turn.

So, how does this actually work?

The force-feedback joystick in the plane sends its position to a flight controller (actually 3 that work in parallel for safety and redundancy, more on that later). The flight controller interprets the position as a turn rate or climb rate command (for left/right or forward/back). The flight controller also reads a bunch of sensors (gyroscope, accelerometer, magnetometer, air pressure, GPS, etc) to develop an accurate estimate of the airplane’s state: roll, pitch, yaw, velocity, position, etc. Using the current state from the sensor fusion algorithms and the desired state from the joystick, the controller does a bunch of aerodynamics and control theory math to compute the control surface position necessary to bring the aircraft to the desired state. Mixed into this is error checking, envelope protection, and other various safety measures to make sure the aircraft never enters an unsafe state.

Unlike a traditional airplane, it becomes impossible to command the airplane into a stall, a spin, unsafe attitudes, or other bad states. This is the key to the safety of the system: it prevents the common mistakes that pilots make that lead to disastrous consequences.

To make sure that this system is always functioning, everything is single-fault tolerant. That means that there are no single points of failure. Any fault that might occur–a broken wire, a fried resistor, a bitflip in a processor, a random hang in a kernel–does not affect the functionality of the system. This is achieved by having three flight controllers that take in information from two different sets of sensors (we call them “strings”), independently compute the desired actions to take, and vote on what to do. Each string has its own power source, backup battery, networking hardware, and set of critical sensors.

The only real single point of failure is the engine. We only have one, though the engine itself has redundant ignition systems, fuel pumps, controllers, etc. If the engine were to die, the batteries would keep the system running for ~30 minutes, giving you time to make an emergency landing. If the pilot somehow becomes incapacitated, any passenger can initiate an autonomous emergency landing. And if many things go wrong and the system does fail, there’s a full airframe parachute that can be activated to bring the airplane safely to the ground.

A lot of people will likely wonder: “isn’t removing stick and rudder skills going to make worse pilots”? Short answer: no. The core of what makes a good pilot isn’t stick and rudder skills; it’s good decision making and risk management. For single pilots in GA, it’s even more important. So we are building a system that will give our pilots the tools to focus entirely on decision making and risk management and remove the distraction of stick and rudder that creates so many problems today. We think stick and rudder skills are definitely a necessity for airline pilots flying hundreds of people on board for the extremely rare cases where emergencies do happen and many people’s lives are at risk, but not for an average person flying a four seat airplane to go on a weekend trip to the mountains. Our system makes it impossible to lose control of the airplane, potentially solving 80% of today’s fatal accidents in general aviation.

Fly-by-wire systems typically cost millions of dollars. We intend to build it for much less. How? By leveraging automotive grade components, clever sensor fusion math so that we can use MEMS gyroscopes that cost <$100 instead of laser-ring gyros that cost $1000 if not $10k, and by a first principles approach to the design of our system. This requires that we build a lot of our own hardware. We’ve developed our own control surface actuators, our own display assemblies, we’re developing our own radios and GPS hardware (an aviation grade GPS can cost upwards of $10k, but it’s the same hardware as in a $20 consumer grade GPS).

To take advantage of this automotive style approach requires scale. Enter the final third of the problem: flying isn’t sexy. Modern airplanes look like they are from the 90s. With our first airplane, the Airhart Sling, we are redesigning the entire UI/UX of the flight deck to make it as easy as possible to use, redesigning the cabin to feel much more like a luxury car than an airplane today, and integrating Airhart Assist to make flying much more accessible and much more inviting. You can see previews of the Airhart Sling on our website, https://www.airhartaero.com/. The sexiness of design is extremely important for the economies of scale of an automotive-style approach to work.

There’s a plethora of other problems that make flying cumbersome: weight and balance worksheets, complicated route planning, talking to ATC, lengthy preflight checks, a fractured system of FBOs, difficult access to instruction, the list goes on. We are working on all of these too, but no amount of extra UI features can solve the fundamental problem that aviating itself is hard. So that’s what we’re solving first.

We want people who don’t think about airplanes as a mode of transportation to start flying and are hoping that Airhart will pave the way. Whether you fly planes today or not, I’d love to hear your thoughts. This is a very exciting topic with lots to discuss so I’m very much looking forward to the conversation!

In short, though: they’re developing an autopilot system which completely abstracts the mechanical aspects of flying. Full fly-by-wire, no rudder pedals, no direct control over ailerons or elevators or even throttle, just one stick for up/down/left/right and another for speed. Push left and the plane does a perfect coordinated turn to the left with constant altitude. Impossible to stall or spin or get it into any other bad state. For landing, you basically point it at the runway.

The whole thing seems very optimistic, but the lead guy was an avionics engineer at SpaceX. They’re young and possibly naive, but not dumb. They’re aiming for full single-fault tolerance through triple redundancy on most systems (except the engine).

As for the general idea: well, the first thing that comes to mind is the classic argument between automation vs. not:
On one hand, automation reduces the need for people to learn the fundamentals of flying an aircraft. It also abstracts away so many details that it becomes impossible for a pilot to have a correct mental model of the plane’s state. The automation will still fail at some point and the pilot will have no ability to escape the situation because they have become dependent on it. And it will likely fail with little to no warning, since if it could have known in advance it would have avoided the failure.

On the other hand, most accidents happen for basically stupid reasons. The pilot made the wrong control inputs because they got behind the plane in some way or because they didn’t understand the environment (which may itself be due to their biological senses giving bad inputs, or failing to use or understand the avionics data). Also, this need to just fly the plane takes finite cognitive load which could be better used for higher-level “strategic” decisions. Pilots will be better able to make high-level decisions if the low-level stuff is handled for them.

I don’t have an answer for that dichotomy and I don’t think anyone ever will since it’s fundamental. But it’s worth an effort, IMO. The founders are right about how primitive GA aircraft still are. Will be interesting to see where it goes. They’re partnering with Sling Aircraft for their first model. I don’t know anything about Sling but they seem to be legit.

I mean, it looks like it could be a good idea, but from what I’ve learnt in this thread, it seems to me it will take them tens if not hundreds of millions of dollars, and many years, to try and get such a setup FAA approved. Which means either the aircraft will be priced out of reach of all but a tiny number of people, or it will fail as a business. Or most likely, both.

It’s definitely not cheap. From their site:

*The full price of the Airhart Sling pre-tax is $500,000 with availability predicted for January of 2026. This purchase secures a production slot in the limited first manufacture of the aircraft.

Though a base model Cessna 172 costs $360k today, so it’s not too far out there.

I agree that the regulatory side is going to be the long pole. Maybe it can be done under some kind of experimental license.

I get it is super expensive and difficult for new systems to be implemented but, also, flying is so much safer than it used to be because the regulations are so stringent.

Would you trade the safety you have when flying for a cheaper fare?

Note that this is a general aviation product–it’s not for commercial flight. Commercial flight is indeed very safe, but it’s far from clear that applying the regulation-heavy approach to GA makes it safer (it has about 10x the fatality rate per mile as driving, and about 30x per hour). What it has done is slow development, to the point where most GA aircraft have changed very little since WW2.

No, no it can’t. Flight testing, perhaps, by 2026, but not certified and ready for sale. The timeline is just too short even for a GA aircraft which I’m assuming will be Type Certificated under 14 CFR 23. Those regulations were revamped to be “performance based” but you still need to fully demonstrate compliance and someone with 4 years of GA piloting and some programming skills simply does not have the airworthiness knowledge to pull this off in under 2 years.

I’m aware of and involved in much less ambitious projects by experienced companies which are on 3-5 year timelines.

And “automotive grade” anything will be fun to try to certify too.

Is a Cessna 172 safer today than it was in 1960?

Most Skyhawks were built in the '70s. But anyway, new or newer ones have better avionics. But the airplanes are pretty much the same. (I think after a certain year Skyhawks switched from the 172 type certificate to the 175 type certificate. But it’s been over a decade since I read that so my memory might be faulty.)

I remember reading an analysis once that made the following point: Excluding avionics, piston-engine planes have changed very little over time. There are some improvements in metallurgy and ceramics, and we have learned a few design tricks that tweak the aerodynamics. But big picture… even a Cirrus isn’t very far off from the technology Lindbergh used to fly the Atlantic in the 1920s. It’s more reliable, certainly. But piston engines are still piston engines.

There have been low-tech attempts to make things more idiot-proof for pilots (Og knows we need it!). You had the Ercoupe without rudder pedals and you have Cirrus attempting to spin-proof their planes, but these certainly aren’t game changers

At the same time, airspace and some regulations have become more complicated. Avionics have evolved to mitigate that somewhat, but as technology advances it also becomes more complex in itself. And sometimes having very capable avionics and automation onboard tempts people to penetrate weather they really shouldn’t, so it can occasionally be a negative influence.

I’m unable to envision an aircraft that simplifies flying to the point of driving a car AND does the same for the operating environment. Even if you can make it so sophisticated that it doesn’t require typical pilot skills there’s always weather, airspace and traffic that needs human judgement and intervention. Plus, we live in a world where flight rules have gotten good enough to make commercial air travel really safe and reliable, and I don’t know how you shoehorn this kind of thing in without upending much of it.

I’m certainly open to it, but at this moment it’s hard to see it.

Oh sure, I’m not going to defend their timelines. Dead_Cat made a comment about the price and I pointed out that even their target price is quite high (though not absurdly so compared to other GA craft).

Still… this carries no weight for me. There’s a big company starting with the letter B demonstrating across the board that experience is no substitute for competence.

I suppose it’ll come down to proving they can meet the reliability requirements. With enough redundancy, you can make a lot of things reliable.

I anticipate the experience from SpaceX will be valuable here. They regularly eschew use of specialized space-grade components in favor of ordinary commercial-grades ones plus redundancy. For instance, you can get radiation-tolerant processors built on a sapphire substrate. They cost tens of thousands of dollars and are a tenth the speed of typical processors. Or you can just do everything in triplicate for 10x the perf and 1/100th the price.

Their approach is that you don’t harden components–you harden a system. You can build a hardened system out of non-hardened components.

It’s not only a question of competence (though it’s obviously important); the system itself doesn’t allow for rushed timelines.

Based on the description copied above, this company will need to deviate from established regulations and means of compliance. That means applying for exemptions, special conditions, and equivalent level of safety findings. These are regulatory actions that take months to review and get approved, each. And there’s only so many resources at their local certification office, so the can’t all be done at once. That assumes you have all your certification plans and procedures ready to go, and there are no challenges or follow-on issues to resolve.

It took three months to get a simple, routine, paint scheme equivalent safety finding to allow a stripe that was borderline out of specification for one of my customers. I’m six months into negotiating a cabin modification with the FAA that’s been done before, just not on the exact aircraft model.

If you’re not prepared to manage this stuff, no matter how good your design is, you’re facing long, frustrating delays. The text of the rules seem straightforward, but they often aren’t.

Based on the description above, this company is not prepared for the certification process. They’re trying to do something rather significant, in a timeline typically appropriate for smaller projects.

Like I said, I’m not going to defend their timelines.

Though apparently they were doing some very basic flight testing almost two years ago:
https://www.airhartaero.com/post/our-first-fly-by-wire-flight

Spacecraft avionics have to go through the FAA, too. It’s obviously a wholly different set of regulations, but they at least have some exposure to the process.

I’ll grant that I assumed they were new/announcing now based on how I interpreted the quoted text. Adding a couple of years starts to be on a more reasonable scale, but I still think it’s ambitious.

There are so many players in the “air taxi” space right now and a lot of them are pipe dreams at best.

Yeah, I think what’s new is that they got some VC funding. Hacker News is connected to Y Combinator, which is a sort of startup incubator. They seem to have also gotten money from L2 Ventures and Soma Capital.

I don’t think this has anything to do with air taxis, which I agree are oversaturated. They’re just trying to open up the GA market to more people–especially those concerned about safety (which is mostly awful). It’s mostly still a normal plane, though, not some scaled-up quadcopter.

It’s all Part 23 Normal Category aircraft, unless it’s big enough to become a Part 25 Transport Category aircraft, or it’s unmanned, or very light sport, or definitely a helicopter, or amateur built. An aircraft is certifiied for airworthiness, and then you add on the operational requirements (over water equipment, far north operations, charter, etc).

The difference between 23/25 is primarily based on aircraft size, not style or operational intent.

While it’s common to assume “general aviation” means little Cessnas, it also means the big ones, or a Gulfstream G700, of it’s not taking on paying customers under charter or scheduled operations.

These guys seem to want to sell private “flying cars” and not “chartered taxi” but the same physical aircraft design could do both or either depending on the day, and the type certificate would be created under the same rules.

I don’t get that impression at all. They want to address the “little Cessna” end of the GA market. They want to sell a modified version of an aircraft right at that point. It’ll still require a pilot certificate to fly.

The comparison with a car is just an analogy–they aren’t trying to build a flying car. It’s just that these craft are still at a Model T level of development with their controls, and they want something automated like a modern car. But that’s the end of the analogy.

I suppose it’s perspective and semantics. The closest we have to a “flying car” is the “little Cessna” today! In the airworthiness nerd space though, it’s the same rules and paperwork!

It’s an interesting project in terms of concept, and I like that companies are trying to shake things up but I tend to be cynical. There are definitely safety issues that can be better addressed. The industry isn’t really structured to face them, though.

Fair enough. I’m putting air taxis and “flying cars” in the same basic mental category: electric, VTOL, and partially or fully automated. Probably no pilot certificate required.

But sure, a 172 is sorta flying car-ish in the sense of being about the same mass and possible to fly by a normal person, albeit with a fair amount of training. But I think it’s pretty different from the air taxi market, which has zillions of almost identical contenders. These guys aren’t competing with them, so maybe they have a chance. It’s a much smaller market, but not everyone has to be the next unicorn.

Cynicism is certainly warranted, especially by anyone looking to invest in them. But Y Combinator likes to throw small amounts of money to lots of places in the hope they’ll have a few winners. Worth a try.