What if... Modernizing GA

[flyingcheesehead]

So I went down the rabbit hole of fantasy-shopping for airplanes after reading the I have tasted speed, and I like it thread.

Given that what I fly right now is probably as good as it gets in terms of price/performance ratio (M20R, 175 KTAS/12gph), and is relatively new (1997), it's hard to get excited about much. To get more capability while remaining within the realm of affordable, I have to start looking at 50+ year old airplanes!

It got me thinking about things that could be done better with some modernization of GA - Both from the airframe and the manufacturing side - If we took some of those old designs and did new things with them.

So - If you could take an existing airplane and make a few things better about it and have it fit your mission - What would they be? What sorts of manufacturing techniques could be used to make them easier to build without sacrificing strength, longevity, and maintainability?

A good example for me is the Ravin 500 experimental. It's practically an exact copy of the PA-24-260C Comanche, except made of newer materials, and the performance is great.

Were I to upgrade, though, a twin would probably be the next step. I live a stone's throw from Lake Michigan, so having something that could safely cross the Great Lakes even if it wasn't faster would save me a significant amount of time on many trips. I've always liked the Twin Comanche for its efficiency, and the 310 for its performance and comfy cabin.

The Twin Comanche had a bunch of modifications available for it that really made it a better airplane: Robertson STOL and the "Miller Mods" being the big ones: R/STOL added a dorsal that notably decreased Vmc and allowed for a 200-pound gross weight increase in addition to the obvious better takeoff performance. The Miller mods included a dorsal larger than stock but smaller than R/STOL which we can ignore, but also had an extended nose with baggage compartment, extended nacelles with baggage compartments, aux fuel tanks, and 200hp IO-360s to replace the stock 160hp IO-320s. Combine all that with the Rajay turbonormalizers, and you had an airplane with an impressively wide performance envelope.

So, if we built an airplane that had all those from the start, that would be great - But the other negative about both single and twin Comanches is that they were somewhat labor intensive to build, which is why Piper didn't bring them back after the flood in Lock Haven, opting to instead replace them with the not-even-close Arrow and Seneca that were far easier to build. So, if we were to design the internals to use modern automated manufacturing processes, CNC, 3D printing, etc could we make something simpler than the Arrow/Seneca?

The 310's major drawback, to me, is the lack of a back door like the Seneca or B58 have. Other than that, the 310R is a dang fine machine... Though it could probably use some simplified systems. I think it has something like 11 fuel pumps, for example!

Then I got to thinking - Why do I even need a twin? I'm looking for something reliable enough to get across the lake safely. What if it were a hybrid, with a small turboshaft engine driving a genset that fed a pair of electrically driven push-pull props? That would eliminate the safety issues with a normal twin, plus give a smoother ride. Batteries could drive the motors for just long enough to get to shore/nearest airport in an emergency, and the engine could charge them up while taxiing, provide some additional thrust during climb and cruise, and provide bleed air for deicing.

All right, enough outta me - What are your crazy and not-so-crazy ideas for what and how to build a better, modern, GA aircraft?

 

[Barrett50]

I'll get to it.

Years ago, when the SR20 Cirrus came out I was thinking it's about time for me to get out of my ragged old Bonanza. It was long in the tooth back in 2005, and I was waiting, waiting, waiting for the Cirrus to be delivered. Finally the day came and I started at the specs(which I always do rather than the glossy stuff). I was reading through, and each time I read something it was like I was reading the specs from a 60YO Beech Bonanza. Cirrus 215HP, Bo 225. Cruise speed Cirrus 155, Bo cruise 158. Fuel burn within 1 gal/hour. Payload Cirrus 779, Bo 785. Service ceiling Cirrus 17,900, Bo 18,700. WTH? They can't do better after 60 years? It has a BRS, it has fixed gear, it has a roomy interior and a cool side stick. Better avionics suite. But - the reality is, after 60 years I'm expecting earth shattering performance boost. I still have a Bonanza...

Now, crazy ways to improve modern planes. Take if from someone who is looking at a McLaren car. The whole chassis tub is CF. It weighs 186Kg or 406Lbs. The - whole - monocoque chassis. Comparable Ferrari 488 alum chassis weighs about 850. CF is everywhere on the McLaren. CF is about 45% lighter than the same structural element made in Alum. Now, imagine if we could knock 30% of the weight off a modern plane, all formed in CF?

Next, has already been done by the Rutan people. The canard pusher design. The only reason a plane has a fuselage is to support the heavy, bulky, performance robbing tail. So, cut it off. The tail of a plane actually uses negative lift to make the plane stable. It does ZERO lifting at all back there. I had a Vari-Eze in the late 80s with a C90 engine. The same engine in the Ercoupe and Luscombe. I could blister along at about 180-185MPH while the Ercoupe and Luscombe are lucky to do 90-100MPH. The Vari-Eze is a fiberglass build. Imagine what can be done with a canard pusher with a CF substrate.

Moving on to engines. Face it, the Otto cycle engine is a worn out beast. The air cooled Otto cycle is lowest form of pond scum for performance. At the very minimum go to a modern Atkinson cycle type recip engine, with water cooling, VVT, stratified charge direct injection. Whatever is taken up in weight gain for the cooling jacket can be EASILY offset with much greater energy density per pound. The Porsche people tried it with the PFM and failed miserably. So, call Toyota. Have them start with the modern Prius 140HP, and build it for 100 octane fuel, with aggressive spark curve and detonation detection and adjustment. Make it single lever and let the computer lean for altitude. Water cooling gets rid of shock cooling, and overheating during descent and climb.

Alternately take the old Allison 250 turbo-shaft. There are thousands of them built for various aviation models like the Hughes 500(licensed to RR now). It's been up to 420SHP in some applications. Start building 10,000 at a time to get the production cost down some, and use it in a CF built canard plane with 3-4 pax. It should cruise in the teens at near 400MPH on 30GPH. Super reliable, low moving parts, legacy support, and who doesn't like the smell of Jet-A? Even better, put two of them one on each wing. Asymmetrical thrust might be an issue, but it could be solved with some aero engineering.

If I had a spare 100M I would start engineering such a plane. The only place it doesn't work well is unimproved strips. So, make the canard bigger, and put the engine/prop in front. Velocity aircraft has something smaller but like this design. I wonder what the perf is on one of those.

 

[AV8R_87]

Agree with a lot of what you're saying, but VVT is practically useless in the narrow power/torque band we use those engines. And a Prius hybrid drivetrain is also useless, since you have no real opportunity for regen. Instead of the modified Arkinson cycle, a modern turbo (or turbocompounded) design would probably be better and lighter.

Key point is "mass" production. Whatever design we produce, it needs to be made in large enough volumes to allow it to be made by complex machines in short amounts of time. You can't have 20 skilled workers spend 100+ hours each drilling holes and bucking rivets, plus other labor-intensive tasks.
Avionics panels need to be built and installed like car instrument clusters, not have someone work upside-down under the panel to wire it up.

Tort reform. GA won't be cheap (and mass-produced) if half the cost is money for the next lawsuit because Joe filled up the tanks and put four 250lb pax in his 172, but somehow it's Cessna's fault and they have to settle in court because it's cheaper than fighting it for three years.

 

[asicer]

So, call Toyota. Have them start with the modern Prius 140HP, and build it for 100 octane fuel, with aggressive spark curve and detonation detection and adjustment. Make it single lever and let the computer lean for altitude. Water cooling gets rid of shock cooling, and overheating during descent and climb.

I have a feeling Toyota would look at the Rotax 915 iS an say "eh, you got this".

 

[TCABM]

I have a feeling Toyota would look at the Rotax 915 iS an say "eh, you got this".

That’s great, but 140hp is peanuts. The 200-350hp spot is what needs real attention.

It’s the one place I can see a turbine generator driving an electric motor. The question then becomes whether or not enough fuel can be carried to make a 4hr leg with 45mins reserves possible.

 

[brcase]

Why do I even need a twin? I'm looking for something reliable enough to get across the lake safely. What if it were a hybrid, with a small turboshaft

or you could mount something like this underneath just behind the cockpit. With some tuning I bit it would run on 100LL. Note it is retractable.

 

[Sac Arrow]

The thing about it is all the things we need to make automobile engines perform well are nearly irrelevant in an aircraft engine. Things like variable valve timing, and even variable spark timing give little return. These engines turn slowly, spend 95% of their time at cruise RPM, and the difference between full takeoff power RPM and cruise RPM is usually only 200 or so, so good performance over a wide RPM band gains next to nothing. Speed the engine up for more power? Then you are in to reduction drives, adding weight. Then there is the issue of cooling it, now you need a liquid cooling system, adding more weight and an additional failure mode. A clean sheet gasoline engine is still going to end up looking a whole lot like an airplane engine. Look at Rotax. Certainly the ability to run on unleaded gas and maybe a spark retard for detonation control might be a nice upgrade. A wide band 02 feedback control loop would be nice but how much time do we really spend fiddling with the mixture control?

I think the big advances will be in the development of dedicated aviation diesels, vs. automotive adaptations like Thielert. And there are a couple out there that look promising. Turbines are fairly inefficient for most GA applications where the majority of the flights occur below altitudes where turbines become efficient.

 

[Bell206]

If we took some of those old designs and did new things with them.

If I had a spare 100M I would start engineering such a plane.

No need to wait or take a loan out. Buy a scrap Commanche of your flavor with no engines, disassemble it, scan it, 3D print, reassemble, slap a couple Rotax on it, and fly away. Never could figure why someone hasn’t done this yet with all the cheap technology around. Plus this takes care of all the issues consistently mentioned why new GA aren’t available.

What if it were a hybrid, with a small turboshaft engine driving a genset that fed a pair of electrically driven push-pull props?

Somebody already beat you to it with a slightly different configuration.

So, call Toyota.

They’ve already been there and done that: TAA-1. They also worked on converting a Lexus engine for use in the TAA-1. But I doubt they would have time now as they are frying some large aviation fish at the moment. And so is Honda and Hyundai.

 

[bbchien]

I was very close last year to pulling the trigger on a VL3. 140 hp Trubocharged Rotax, but no lightning protection and no ice protection. 8 gph. 175 kts.

But had it hit these shores b4 Mosaic--> Then it registers as an E-lsa. No bueno. So, I'm loading up my Seneca with an avionics update. Now they're going to tkae away my fuel.

The problem is not just technology. It's also government.

 

[Barrett50]

I'd like to say a big thank you - to all the critics. You all must feel much better now. Seems to me, based on the responses that the air cooled Otto cycle, with a metal fuselage and a tail is the best we can do. Way to spread your wings people.

 

[2-Bit Speed]

Speed the engine up for more power? Then you are in to reduction drives, adding weight. Then there is the issue of cooling it, now you need a liquid cooling system, adding more weight and an additional failure mode. A clean sheet gasoline engine is still going to end up looking a whole lot like an airplane engine.

but:

Look at Rotax.

 

[Barrett50]

No need to wait or take a loan out. Buy a scrap Commanche of your flavor with no engines, disassemble it, scan it, 3D print, reassemble, slap a couple Rotax on it, and fly away. Never could figure why someone hasn’t done this yet with all the cheap technology around. Plus this takes care of all the issues consistently mentioned why new GA aren’t available.

I like how you've just done away completely with certification. Presuming then, this would be an EXP 51% home build aircraft? Maybe I'm mistaken but I took the OP at being a certificated design as he already mentioned the Raven(EXP) redo of the Comanche. Last sentence, how to build a modern, GA aircraft, I'm taking to be a cert plane. I could be wrong.

Plus, the Raven is not a departure from the standard GA design, it's a clone of a cert airplane.

 

[Dana]

Technology has improved a bit, but physics and aerodynamics haven't changed.

 

[Barrett50]

I was very close last year to pulling the trigger on a VL3. 140 hp Trubocharged Rotax, but no lightning protection and no ice protection. 8 gph. 175 kts.

But had it hit these shores b4 Mosaic--> Then it registers as an E-lsa. No bueno. So, I'm loading up my Seneca with an avionics update. Now they're going to tkae away my fuel.

The problem is not just technology. It's also government.

What the FAA did to Beech with the cert of the Starship was a crying shame. Add to that, the feds then slapped an extra lux tax on the plane. It was a great design from the start, but the FAA mandates added thousands of pounds.

 

[hindsight2020]

how to build a modern, GA aircraft, I'm taking to be a cert plane. I could be wrong.

I mean, at least when it comes to the powerplant side, which is the one I blame the most for the cost gridlock in this hobby anyways, I believe the premise to be an oxymoron.

Certification burdens in present language is the primary obstacle to the very economic facilitation required to lower per-unit costs in the first place. Which makes the proposition of the already *simple ask (*for mass-production automotive OEM industry titans) of offering powerplant options to replace air cooled tractor mills of the 200-300hp variety, a non-starter/catch-22.

Homebuilders aren't really in a position to reliably/at-scale homebrew the engine tech, like they can the airframe. Which is not a distinction without difference as I argue what we have is a powerplant affordability/interoperability problem, not an airframe problem in this hobby. This is even more so the case in the sclerotic fac-built side.

 

[Bell206]

this would be an EXP 51% home build aircraft?

Yes. But there's nothing that prevents you from following the same rules as a certified aircraft just without the exorbitant cost of doing so. So why not build something you can afford and enjoy? And copying an existing flying model gets you a definite head start.

Unfortunately, given the declining size of the private Part 91 market, I doubt there will be any new models produced by the legacy OEMs. However, where there is a market, they'll design and produce a new clean sheet aircraft all day long.

 

[Brad W]

I have not seen that Ravin before. Intersting!

I've never been a fan of the pipers though, because of the one door and no windows thing....
Except your sidebar about going twin reminded me of my time trying to get my multi rating in an old round tail Piper Apache 150 (PA-23-150). It was an old underpowered dog, but I remember really liking the airframe. Large, roomy, very stable and comfortable to fly. I even liked the way it looks in an old vintage way... I never liked the looks of newer square tailed versions even though they are no doubt better in most ways. It would be interesting to see a modernized and properly powered version of an old PA-23-150 (or PA-23-160)

The twin Comanche was a nice looking bird, but I never had the pleasure of doing anything more than looking at them

 

[Barrett50]

Yes. But there's nothing that prevents you from following the same rules as a certified aircraft just without the exorbitant cost of doing so. So why not build something you can afford and enjoy? And copying an existing flying model gets you a definite head start.

Unfortunately, given the declining size of the private Part 91 market, I doubt there will be any new models produced by the legacy OEMs. However, where there is a market, they'll design and produce a new clean sheet aircraft all day long.

Well, then, it's already been done by Raven. How many 51% kits have they delivered? How many completed? And, it has an old Otto cycle tractor engine to boot. There's not a lot of info on the site. All I can see is they increased the wing loading and power loading factor by about 50%, and changed from Al to fiberglass? Meh - if we're going to talk about the GA market, EXP is a tiny fraction of all GA. RV-10, Raven, Velocity there is a place for that, but Joe Bagadonuts isn't going to pony up $120k for a box of FG, resin and some bars of Al to make it.

 

[midwestpa24]

Only what I've heard third hand, but I've heard the Raven may look like a Comanche, but does not fly like one.

The OP compared a new Cirrus performance to old Bonanzas. While yes the numbers are similar, Cirrus is doing it faster and easier than Beech, with fixed gear, more comfortable cabin, and greater safety and convenience features.

The same technological barriers are evident in commercial aircraft too. Look at all modern airlines, they all follow the same basic design. Tubular fuselage, mid mounted wings, pod mounted engines. The variations have become so minimal it takes a trained eye to tell the difference between a 787 and A350. We aren't breaking ground in engineering anymore, just refining it in the margins.

 

[flyingcheesehead]

But - the reality is, after 60 years I'm expecting earth shattering performance boost. I still have a Bonanza...

I'm certainly not expecting earth shattering performance boosts, all else being equal. Physics doesn't care how fast you want to go. What has changed is materials and manufacturing technology that lets us do things today that simply weren't possible in the 60s-70s heyday of GA.

Now, crazy ways to improve modern planes. Take if from someone who is looking at a McLaren car. The whole chassis tub is CF. It weighs 186Kg or 406Lbs. The - whole - monocoque chassis. Comparable Ferrari 488 alum chassis weighs about 850. CF is everywhere on the McLaren. CF is about 45% lighter than the same structural element made in Alum. Now, imagine if we could knock 30% of the weight off a modern plane, all formed in CF?

Question: Why are the modern composite certified planes not that much lighter than the metal ones? Is the FAA requiring them to be stronger, or to be tested in such a way that they need to be stronger, or...??? Would it make sense to have a metal spar, and possibly some other metal innards as well, and a composite skin?

Next, has already been done by the Rutan people. The canard pusher design. The only reason a plane has a fuselage is to support the heavy, bulky, performance robbing tail. So, cut it off. The tail of a plane actually uses negative lift to make the plane stable. It does ZERO lifting at all back there. I had a Vari-Eze in the late 80s with a C90 engine. The same engine in the Ercoupe and Luscombe. I could blister along at about 180-185MPH while the Ercoupe and Luscombe are lucky to do 90-100MPH. The Vari-Eze is a fiberglass build. Imagine what can be done with a canard pusher with a CF substrate.

Why hasn't there been a certified canard pusher in the "normal" four-seat size? The only canards that are certified seem to be larger. Was it simply that that design didn't become normal/accepted until after the production downturn?

Moving on to engines. Face it, the Otto cycle engine is a worn out beast. The air cooled Otto cycle is lowest form of pond scum for performance. At the very minimum go to a modern Atkinson cycle type recip engine, with water cooling, VVT, stratified charge direct injection. Whatever is taken up in weight gain for the cooling jacket can be EASILY offset with much greater energy density per pound. The Porsche people tried it with the PFM and failed miserably. So, call Toyota. Have them start with the modern Prius 140HP, and build it for 100 octane fuel, with aggressive spark curve and detonation detection and adjustment. Make it single lever and let the computer lean for altitude. Water cooling gets rid of shock cooling, and overheating during descent and climb.

Why exactly did the PFM fail?

There's definitely been a lot of developments in automotive engine technology that haven't made their way to GA, likely due to the cost of certification... And it's just silly that we don't have affordable piston FADEC with some of these other technologies. Our engines aren't THAT much different - Look at all the various configurations that are possible in something like a Garmin GPS. You could, relatively easily, create a generic FADEC that worked for any of our existing engines. Maybe Garmin will get on that for us.

Alternately take the old Allison 250 turbo-shaft. There are thousands of them built for various aviation models like the Hughes 500(licensed to RR now). It's been up to 420SHP in some applications. Start building 10,000 at a time to get the production cost down some, and use it in a CF built canard plane with 3-4 pax. It should cruise in the teens at near 400MPH on 30GPH. Super reliable, low moving parts, legacy support, and who doesn't like the smell of Jet-A? Even better, put two of them one on each wing. Asymmetrical thrust might be an issue, but it could be solved with some aero engineering.

Now you're talking! That's exactly the kind of thing that I'd like to see.

Agree with a lot of what you're saying, but VVT is practically useless in the narrow power/torque band we use those engines. And a Prius hybrid drivetrain is also useless, since you have no real opportunity for regen. Instead of the modified Arkinson cycle, a modern turbo (or turbocompounded) design would probably be better and lighter.

I was thinking the VVT would be used simply to vary the power cycle "compression" ratio for the Atkinson cycle. But yes, the relatively narrow operating bands for GA engines should make improvements a piece of cake... So why are we still flying 40s and 50s tech? (Yes, I know. The FAA.)

Key point is "mass" production. Whatever design we produce, it needs to be made in large enough volumes to allow it to be made by complex machines in short amounts of time. You can't have 20 skilled workers spend 100+ hours each drilling holes and bucking rivets, plus other labor-intensive tasks.
Avionics panels need to be built and installed like car instrument clusters, not have someone work upside-down under the panel to wire it up.

Yes!

But seriously, why do we have people doing these tasks? It's not like in today's world you need a 6-7 figure automotive manufacturing robot to do a lot of these things, when there are 4-figure CNC machines available.

Tort reform. GA won't be cheap (and mass-produced) if half the cost is money for the next lawsuit because Joe filled up the tanks and put four 250lb pax in his 172, but somehow it's Cessna's fault and they have to settle in court because it's cheaper than fighting it for three years.

I was thinking about this a lot too... But the real holy grail here is getting the planes to not crash in the first place. Garmin has done some great things already with their ESP and autoland systems - I think the next step is to get rid of TAS and TAWS, and actually have the plane maneuver if the pilot doesn't. It's worth looking at ways to stop the same old stupid pilot tricks, with a big red override button that says you accept all liability for pushing it.

I like how you've just done away completely with certification. Presuming then, this would be an EXP 51% home build aircraft? Maybe I'm mistaken but I took the OP at being a certificated design as he already mentioned the Raven(EXP) redo of the Comanche. Last sentence, how to build a modern, GA aircraft, I'm taking to be a cert plane. I could be wrong.

Yes, I was mostly meaning something certified, or certifiable at least. A lot of the cost of building an airplane is in the labor, and we have technology to make this way easier.

Technology has improved a bit, but physics and aerodynamics haven't changed.

You don't need to change physics and aerodynamics. Look at the R/STOL Miller Twinkie for example - For whatever reason, Piper didn't do those things from the factory, and at the time the market was large enough to support the aftermarket modifications, which are all improvements on the original design. So build 'em in from the start...

Also, composites allow us to make things that just can't be done with sheet metal, including making more aerodynamic shapes. Did you know, for example, that part of the reason the DA40 is so fantastically efficient is that they designed the fuselage and tail such that the compression wave from the nose pushing through the air, when it reacts with the surrounding air and gets pushed back in, hits the aft fuselage in such a way that it gives the plane a bit of a push? That's not breaking the laws of physics, it's using them to your advantage. Older planes couldn't do that because the contemporary materials and manufacturing tech wouldn't allow for it, but that's a thing we can do now.

It's fun to think of the possibilities, absent the realities of FAA certification and lawsuits.

 

[flyingcheesehead]

Only what I've heard third hand, but I've heard the Raven may look like a Comanche, but does not fly like one.

The OP compared a new Cirrus performance to old Bonanzas. While yes the numbers are similar, Cirrus is doing it faster and easier than Beech, with fixed gear, more comfortable cabin, and greater safety and convenience features.

The same technological barriers are evident in commercial aircraft too. Look at all modern airlines, they all follow the same basic design. Tubular fuselage, mid mounted wings, pod mounted engines. The variations have become so minimal it takes a trained eye to tell the difference between a 787 and A350. We aren't breaking ground in engineering anymore, just refining it in the margins.

They all saw what the FAA did to the Beech Starship... And considering that one failed aircraft design at the airliner level can sink the manufacturer, they're not trying very many radical designs.

 

[Barrett50]

Only what I've heard third hand, but I've heard the Raven may look like a Comanche, but does not fly like one.

The OP compared a new Cirrus performance to old Bonanzas. While yes the numbers are similar, Cirrus is doing it faster and easier than Beech, with fixed gear, more comfortable cabin, and greater safety and convenience features.

The same technological barriers are evident in commercial aircraft too. Look at all modern airlines, they all follow the same basic design. Tubular fuselage, mid mounted wings, pod mounted engines. The variations have become so minimal it takes a trained eye to tell the difference between a 787 and A350. We aren't breaking ground in engineering anymore, just refining it in the margins.

I did that comparison, and I also mentioned those factors. For a 10X increase in price over the older Bo, I was expecting way, way more in performance. And, didn't get it.

 

[Dana]

... if we're going to talk about the GA market, EXP is a tiny fraction of all GA.

I think it's a wee bit more than a "tiny fraction" these days...

 

[Dan Thomas]

If I had a spare 100M I would start engineering such a plane.

You are right. 100 million would be a good start, nothing more.

Moving on to engines. Face it, the Otto cycle engine is a worn out beast.

So, which modern non-electric automobile or truck does not have an Otto-cycle engine? If its such a worn-out beast, why are manufacturers still making nearly 100 million of them every year, worldwide?

Tort reform. GA won't be cheap (and mass-produced) if half the cost is money for the next lawsuit because Joe filled up the tanks and put four 250lb pax in his 172, but somehow it's Cessna's fault and they have to settle in court because it's cheaper than fighting it for three years.

As long as there are deep pockets, there will be people looking to (a) blame others for their mistakes, and (b) clean out those pockets.

 

[Barrett50]

I think it's a wee bit more than a "tiny fraction" these days...

I dun know. 2%? A bit more?

 

[Bell206]

Why are the modern composite certified planes not that much lighter than the metal ones?

It depends on how and why the composites are used and the associated load paths. In a number of aircraft, composites are used design structures that are unavailable using aluminum production methods. So weight savings is not always the primary reason to use composites.

And it's just silly that we don't have affordable piston FADEC with some of these other technologies. Our engines aren't THAT much different

So why are we still flying 40s and 50s tech? (Yes, I know. The FAA.)

Not really. It’s simply driven by the intended market. Every other viable aircraft market has FADEC controls and upgraded engines.

But seriously, why do we have people doing these tasks? It's not like in today's world you need a 6-7 figure automotive manufacturing robot to do a lot of these things, when there are 4-figure CNC machines available.

Boeing tried to automate locating and riveting structures. While it worked in very specific locations, after they spent millions/billions (depending who you talk to) to make it work everywhere, they brought back the human riveters. There still are some processes computers haven't mastered yet.

It's fun to think of the possibilities, absent the realities of FAA certification and lawsuits.

Or simply apply those possibilities to building a single aircraft just for your fun vs trying to make it a money-making venture?

I dun know. 2%? A bit more?

Depending on whose numbers you use, the E/AB portion of the Part 91 GA private/recreational market is closer to 30-40%.

 

[455 Bravo Uniform]

To your point about high tech, the old dinosaur mill can be managed with electronic process controls and button-pushing systems management by the pilot.

Startup and run-up: system self checks. Taxi leaning. Take off. Climb cruise. Cruise. Descent. Maybe even landing or go-around. Manage throttle opening, mixture, ignition timing. Can all go to manual control just like the red autopilot override.

Checklists: should come up on the screen automatically based on the sensed condition of flight and GPS. Cruise? Are cowl flaps closed?

Yeah, sure, some inherent safety and human factors here to deal with, but it would be and advancement even keeping the airframe designs and engines. This would be a step-change. Not sure it’s any cheaper or easier to certify. Maybe?

 

[asicer]

So, which modern non-electric automobile or truck does not have an Otto-cycle engine?

Those with a Diesel-cycle engine.

And those with an Atkinson-cycle engine. There's also the Miller-cycle to consider as well.

 

[Dan Thomas]

Those with a Diesel-cycle engine.

And those with an Atkinson-cycle engine. There's also the Miller-cycle to consider as well.

Some academic sources consider the Diesel to be an Otto-cycle engine. The basic Otto involves intake, compression, power and exhaust. Suck, push, bang, blow. The only big difference (besides compression ratio) is the presence of spark with the gasoline engine.

Atkinson and Miller engines are merely variations on the Otto engine. Valve timing, forced induction, and so on. They are more efficient, and I see that Toyota and Mazda and have working on them, with Mazda using it in some vehicles. But it STILL uses a piston in a cylinder, just like the first autos did, and that principle came from Thomas Newcomen's steam engines of 1712. James Watt improved on it.

The real departure from the Otto cycle came with the invention of the turbine engine by a Brit, Frank Whittle, and a German, Hans Von Ohain, independently and at about the same time. The idea had been around before that, but not in a compact and light form for aviation. It used the Brayton constant pressure cycle, and we see it everywhere in aviation today. Every airliner, nearly every helicopter, every fighter jet and bomber, and also in many gas-fired powerplants.

 

[Dana]

I dun know. 2%? A bit more?

I'm pretty sure Van's alone is outselling all of the legacy GA manufacturers nowadays.

 

[StraightnLevel]

1) What about a Wankel engine? Light weight, very small and narrow profile, and the existing designs already have a dual ignition configuration.

2) Unleaded fuel with a closed loop control system would improve power and efficiency significantly.

3) An efficient/fast plane should be a retract. Why? Simple physics - drag. The VL3 mentioned above is a great example of how this works.

4) Composite construction, like Cirrus, the VL3 and others. This opens the door for improvements in drag and weight.

5) Accept a life limit on new light airframes, and use that constraint to lower weight and cost. Even if the airframe life is then limited to, say, 8k hours, who cares? The vast majority of GA planes take many decades to get to 8K, if ever. What's the average pilot's usage? 100 hrs/year? 150?

Also, I'll agree with the earlier post on Bo vs. Cirrus. I started looking at used SR22s about a year ago. I ended up buying a Bo with tip tanks, for a small fraction of the price of a used Cirrus. Almost no performance difference, and the newer, slicker Cirrus design is offset by the drag of the fixed gear.

 

[Dan Thomas]

1) What about a Wankel engine? Light weight, very small and narrow profile, and the existing designs already have a dual ignition configuration.

Homebuilders have been trying them for nearly 50 years. Drawbacks include cooling problems at high power settings, causing warping of the cases and resulting in leakage around the rotors. A PSRU is also necessary. Wankel and John Deere did try an aircraft version and gave up on it. Diamond is producing a 50 HP version, and a 95 HP version is in development. These low power affairs might be reflecting the cooling difficulties at higher HP. Time will tell. https://www.diamondaircraft.com/en/austro-engine/r-series/overview/

3) An efficient/fast plane should be a retract. Why? Simple physics - drag. The VL3 mentioned above is a great example of how this works.

Simple physics also include increased induced drag from the weight of the retraction system. See the quotes from Barret50 farther down, here.

5) Accept a life limit on new light airframes, and use that constraint to lower weight and cost. Even if the airframe life is then limited to, say, 8k hours, who cares? The vast majority of GA planes take many decades to get to 8K, if ever. What's the average pilot's usage? 100 hrs/year? 150?

The Cirrus SR20 and SR22 both have a 12,000 life limit on the airframes.
The Cessna 350/400/Corvalis/ttX have a 25,200 hour airframe life limit.

Now these limits will not appeal to flight schools, many of whom have 172s with way over 20,000 hours on them. To have to write off a Cirrus with around half that will not please them at all, as flight training is already a marginally profitable venture. Making it worse is the special training required to do airframe repairs on the composite structures.

Cirrus 215HP, Bo 225. Cruise speed Cirrus 155, Bo cruise 158. Fuel burn within 1 gal/hour. Payload Cirrus 779, Bo 785. Service ceiling Cirrus 17,900, Bo 18,700.

I ended up buying a Bo with tip tanks, for a small fraction of the price of a used Cirrus. Almost no performance difference, and the newer, slicker Cirrus design is offset by the drag of the fixed gear.

So how much did that retractable gear gain? Nothing, apparently, considering the Bo's extra 10 HP. Cirrus went with fixed gear, appropriately faired, and matched the Bo's numbers while avoiding the cost and weight and maintenance hassles of retracts, and the liability of the guy that forgets to put the wheels down. Cessna did the same thing with their composite airplanes.

 

[asicer]

Some academic sources consider the Diesel to be an Otto-cycle engine.

I'm pretty sure my university thermodynamics class made a distinction between the two.

But then again, I remember more about Karnaugh than Carnot.

 

[Barrett50]

So how much did that retractable gear gain? Nothing, apparently, considering the Bo's extra 10 HP. Cirrus went with fixed gear, appropriately faired, and matched the Bo's numbers while avoiding the cost and weight and maintenance hassles of retracts, and the liability of the guy that forgets to put the wheels down. Cessna did the same thing with their composite airplanes.

The fully enclosed, with all doors rigged on the Bo likely adds 25-ish knots, or even more. No one measures it because the max gear extension and max gear speeds. But - it's a thing of beauty. It's so robust, the same exact gear stuff with the same part numbers is used on the B55 and B58 Baron, which weighs another 2400Lbs fully loaded.

The Bo gear is 12' wide, uses 7.00x8 tires and disk brakes(some are STC'd). I can get in and out of most places an early Maule can use, but I need to be careful of my nose gear. I've seen guys slam a Bonanza on the runway that I thought was going to split the tail off, and the plane just takes it, no problem. The retract bushings will last 500 cycles, if kept lubed. The only wear item in the whole thing is the brushes on the retract motor.

I do have to do a proof retract on annual. It's always a non-event, and every IA that works on small planes has the wing jacks. It's a 1 hour job to jack it, connect a batt charger, retract it, inspect the doors and extend it again. Some guys have the specific Bonanza/Baron retract trolley, or know where there is one, and doing it there takes 40 min.

It is by far the best retract system on any GA plane ever built, except maybe the manual cranking Culver Cadet taildragger. The Mooney Johnson bar is maybe a distant second but the donuts and the bushings are the weak point. I guess congrats to the Cirrus for almost getting the same speed as the 60 year older and 1/10th price of the early Bo. Well done.

 

[flyingcheesehead]

So, which modern non-electric automobile or truck does not have an Otto-cycle engine? If its such a worn-out beast, why are manufacturers still making nearly 100 million of them every year, worldwide?

Because they're cheap.

Not really. It’s simply driven by the intended market. Every other viable aircraft market has FADEC controls and upgraded engines.

Well... The turboprop world has just been getting FADEC in the last few years (PT6E series). And technically, piston FADEC does exist on the Continental (TS)IOF series. However, I've heard it's something like a $100K premium, so nobody does it.

Or simply apply those possibilities to building a single aircraft just for your fun vs trying to make it a money-making venture?

I've been around long enough to know that nobody who starts a new airplane company ever makes money at it.

Checklists: should come up on the screen automatically based on the sensed condition of flight and GPS. Cruise? Are cowl flaps closed?

Yeah, that would sure be nice.

 

[StraightnLevel]

So how much did that retractable gear gain?

It gained enough to offset the Cirrus' limited life airframe, composite construction, newer/lighter avionics, and about 7 decades of development in GA design.

Now, imagine if you took ALL of those advantages and put them into a single plane. What could it's performance be? BTW, if you look at new small planes in the EU, you'll see that most are now retracts. The far lighter weight resulting from composite construction, life limits, and smaller/lighter more efficient engines allows the retract system to be smaller and lighter, as well.

Have a look at the JMB VL3 and Pipistrel Panthera. Why aren't they certified in the US?

 

[StraightnLevel]

The Cirrus SR20 and SR22 both have a 12,000 life limit on the airframes.

Now these limits will not appeal to flight schools, many of whom have 172s with way over 20,000 hours on them. To have to write off a Cirrus with around half that will not please them at all, as flight training is already a marginally profitable venture. Making it worse is the special training required to do airframe repairs on the composite structures.

And yet, the SR2x is the highest-selling small plane in North America for....how many years is a row?

If schools hate them so much, why are they buying more new Cirri than Pipers and 172s, and why do so many schools have them in their fleets?

As for "special training", let's compare how many boat, automotive, and racing techs work on composite repairs vs. how many have ever dealt with something like a wing spar inspection AD. Composites have been around for decades, and the skill set to work with them is widely available.

Honestly, I think that an awful lot of V-tail Bonanza owners would be happy if their ruddervators were made of carbon fiber instead of magnesium.....

 

[Bell206]

The turboprop world has just been getting FADEC in the last few years (PT6E series). And technically, piston FADEC does exist on the Continental (TS)IOF series. However, I've heard it's something like a $100K premium, so nobody does it.

Exactly. But it took the Pilatus popularity, ie., market share, for P&W to upgrade an A series to the E series. The interesting part is P&W had already been putting EECs and FADECs on the PT6 series engines in other markets for 20+ years. To add, the "Pilatus" market was/is so strong that Textron developed a new clean-sheet aircraft and GE developed a new clean sheet turbine engine to power it to compete in that market. In reality, nothing out-powers market strength in civil aviation.

 

[Bell206]

Have a look at the JMB VL3 and Pipistrel Panthera. Why aren't they certified in the US?

I believe it was stated in a different thread the Panthera was at the tail end of the EASA CS23 certification process and once that was completed obtain a FAA Part 23 TC by bilateral agreement process.

 

[Barrett50]

I see a lot of critics here, but very little contribution towards the OPs ask. KInda sad. I don't mind critical positions per-se, but to be critical without offering any solution is the weak man's choice.