The $20/hour Cessna 172 experiment—Update

[wanttaja]

“However, due to liability concerns, the airworthiness will be surrendered to FAA prior to delivery and is not included in sale. Buyer will have to obtain their own airworthiness certificate.”

"Post-sale support will be limited from seller...." Kind of a PITA when the seller is the only entity that understands the engine.

Ron Wanttaja

 

[MauleSkinner]

"Post-sale support will be limited from seller...." Kind of a PITA when the seller is the only entity that understands the engine.

Ron Wanttaja

Yup…sounds more like a 172 airframe for parts than a flyable airplane.

 

[LesGawlik]

Except the one who they blamed for the lack of response has nothing to do with certifications, i.e, STCs. So sounds like there was another priority more important than the STC. All pomp and no circumstance.

Then why did it take years and years to get the STC? Are you saying the STC was processed in a commercially reasonable fashion? Because that's not what I got from reading about G100UL.

 

[Bell206]

For sale now

"We are selling to make room for developing a hybrid engine version."
For what, an aircraft?

Looks like the October article in the OP was merely a pre-sale marketing ploy to gain some coverage.

 

[Bell206]

Then why did it take years and years to get the STC?

My bad. I thought you were referring to the OP V8 article since there was no quote in your post. Not the G100UL.

Are you saying the STC was processed in a commercially reasonable fashion?

As I explained in Post 18 the G100UL STC time frame looks ballpark based on what is publicly out there. Don't quite follow what you mean by "commercially reasonable" in the context of a certification process.

 

[kyleb]

Then why did it take years and years to get the STC? Are you saying the STC was processed in a commercially reasonable fashion? Because that's not what I got from reading about G100UL.

Without knowing the facts from both parties, how can you have a legitimate position either way?

 

[SkyChaser]

Without knowing the facts from both parties, how can you have a legitimate position either way?

The ability for the same facts to have a different plausible story depending on who you're talking to escapes many. That is why it's always advantageous to have the first slot when telling a story.

 

[mondtster]

All these threads about similar products are quite predictable. It’s a bunch of people complaining about a development and approval process which they don’t understand and a proposed product that they’ll never buy anyway.

I’ve been directly involved with several clean sheet engine designs and many other major changes for an off highway engine OEM. Even in that environment there is far more money and time spent in development and certification than what folks seemingly think this engine and installation should require.

 

[guest user]

Between this:

“However, due to liability concerns, the airworthiness will be surrendered to FAA prior to delivery and is not included in sale. Buyer will have to obtain their own airworthiness certificate.”

And:

Buyer will be required to sign a hold harmless agreement

I'm not getting a real warm and fuzzy feeling from the seller.

But, I'm sure it is all the FAA's fault...

 

[aftCG]

"We are selling to make room for developing a hybrid engine version."
For what, an aircraft?

Seriously. Do they think they'll bet dealing with a different FAA for that?

 

[kyleb]

Seriously. Do they think they'll bet dealing with a different FAA for that?

They may just want to tinker with an airplane, then beeyotch about the FAA some more.

 

[Bathman]

Rotax 915is with wobbly prop. That's what I would like to see.

 

[Bell206]

Seriously. Do they think they'll bet dealing with a different FAA for that?

Maybe they're going to try and put an O-320 into a boat this time? However, they did mention a 414 in the article....

 

[Kenny Phillips]

https://airfactsjournal.com/2022/10/the-20-hour-cessna-172-experiment-update/

I found this article particularly fascinating. They found a way to address the leaded gas issue. Plus reduced operating costs, emissions and noise. You get one guess what the roadblock is.

The FAA isn't a roadblock; certification is a road, and when you get with the FAA, that road is clearly (and I do mean clearly) defined. You build this, you test it this way, for this long, we [FAA] inspect the bits. Developing and certifying a new [for example] large commercial turbofan family, the GE Aerospace GEnx series, cost upwards of two billion dollars.
I'd imagine a well-run cert effort for a simple engine like this to be a small fraction (as a testing calamity won't set you back $15,000,000!), perhaps 50 million.
Your secondary issue is that you'd likely have to buy the engines in bits, and inspect each part, prior to assembly.
$20/hour for fuel, meh. You can (and people do) put E10 in planes such as this, and fly them. Not legally, but likely safely.

 

[Redneckpilot]

The thing I did not see in the article is the power settings required to yield the stated 500 HP of this LS engine.
The specs I found for a LS-3 is 525 HP at 6200 RPM.
Imagine running the engine in your car or truck at 6200 RPM for 3 hours.

That’s the problem with these auto engine swaps. A V8 engine develops peak HP at a much greater RPM than traditional aircraft engines. Then there’s the gear reduction for the prop.

There was a guy at our field in the late 1990s/early 2000s who had some kind of deal with GM to get Northstar Cadillac engines for aircraft use.
He built some kind of big 4-place composite plane and hung one of those Northstar engines on it. If I remember correctly he had to turn that V8 at around 5500 RPM.
I was stupid enough to get in that thing with him once.
That was the LOUDEST thing I have ever sat in besides a race car! After we broke ground and was climbing out he asks “WHERE DO YOU WANNA GO??” to which I replied “RIGHT BACK WHERE WE JUST LEFT FROM!!”

Part of the deal with GM was he had to fly this thing around to “demonstrate” it.
So he decides a trip to Alaska would be a good idea. (from NC)
He made it as far as Idaho I think when the Northstar gave it up on takeoff. Plane ended up on its back and Cadillac Jack, as we called him, had back issues from then on.

He gave up on the Northstar deal, and ended up with a Pitts and a Cessna 337.

 

[SoonerAviator]

The thing I did not see in the article is the power settings required to yield the stated 500 HP of this LS engine.
The specs I found for a LS-3 is 525 HP at 6200 RPM.
Imagine running the engine in your car or truck at 6200 RPM for 3 hours.

That’s the problem with these auto engine swaps. A V8 engine develops peak HP at a much greater RPM than traditional aircraft engines. Then there’s the gear reduction for the prop.

There was a guy at our field in the late 1990s/early 2000s who had some kind of deal with GM to get Northstar Cadillac engines for aircraft use.
He built some kind of big 4-place composite plane and hung one of those Northstar engines on it. If I remember correctly he had to turn that V8 at around 5500 RPM.
I was stupid enough to get in that thing with him once.
That was the LOUDEST thing I have ever sat in besides a race car! After we broke ground and was climbing out he asks “WHERE DO YOU WANNA GO??” to which I replied “RIGHT BACK WHERE WE JUST LEFT FROM!!”

Part of the deal with GM was he had to fly this thing around to “demonstrate” it.
So he decides a trip to Alaska would be a good idea. (from NC)
He made it as far as Idaho I think when the Northstar gave it up on takeoff. Plane ended up on its back and Cadillac Jack, as we called him, had back issues from then on.

He gave up on the Northstar deal, and ended up with a Pitts and a Cessna 337.

I read it somewhere, but I believe it was limited closer to 220HP in the C172 as that was the highest power available in a certified model. Flat rating an engine capable of producing well over double that figure should ensure that you don't have to be turning 6K rpm in order to develop the necessary power.

 

[Redneckpilot]

I read it somewhere, but I believe it was limited closer to 220HP in the C172 as that was the highest power available in a certified model. Flat rating an engine capable of producing well over double that figure should ensure that you don't have to be turning 6K rpm in order to develop the necessary power.

True enough. I still see no values listed.
If you reduce the RPM by 50% you’re still at 2700-3000 RPM. These engines in a vehicle cruise at 1500 to 2000 RPM at highway speed.

I’m not relying on a conglomeration of GM chinesium relays and circuit boards to keep the fan turning.
I’ll leave the cutting edge to someone else and cling to my dirty Continental.

 

[AlphaPilotFlyer]

These guys again. Have they published an estimated conversion price and installed weight?

There's a reason aero engines are built they way they are, and not like auto engines.

Please explain more….. what is the difference you mention and why an auto engine cannot be a variable replacement.WW2 aircraft used auto engines. All certified diesels are auto conversions……. What’s your point? Please reference technical data so to get a better understanding of your statement.

I think article stated target conversion kit cost as about same as factory overhaul. As noted in other places weight is about 225lbs more than O360 with additional battery, but will likely come down from there should project continue. And yes, structural analysis performed per CAR 3 and part 23.

 

[AlphaPilotFlyer]

"Post-sale support will be limited from seller...." Kind of a PITA when the seller is the only entity that understands the engine.

Ron Wanttaja

The listing states it comes with service manual and software and any auto mechanic withe ECM knowledge can work on it…. Just as any modern car.

 

[AlphaPilotFlyer]

"We are selling to make room for developing a hybrid engine version."
For what, an aircraft?

Looks like the October article in the OP was merely a pre-sale marketing ploy to gain some coverage.

They may just want to tinker with an airplane, then beeyotch about the FAA some more.

sorry you got that out of the article …. Don’t see how how you came to conclusion about it being about “beeyotch”ing……article was was requested to update earlier article and it’s was intended to be factual about progress, and magazine editor found it factual and without such bias. Sorry you somehow came to such an opinion.

 

[AlphaPilotFlyer]

Yup…sounds more like a 172 airframe for parts than a flyable airplane.

Actually, it’s anything but a scrapper from practical sense. It flys better than any c172 and fun to fly. A couple of guys built a couple of hundred hours on it and are now flying for the airlines as a result. No reason it can’t continue. Selling it exposes builder to above average liability risk without practical mitigation, and really only reason for scrapping after flight testing is completed.

 

[AlphaPilotFlyer]

Seriously. Do they think they'll bet dealing with a different FAA for that?

No, seriously, we are not that foolish. Fact is the project started out as an engineering challenge and a fun project. And it was. Our goal was to take this design, learn a lot, and evolve it to hybrid as automotive technology development allowed. We don’t have enough $ or time to both develop the engine and fund cert costs, so hybrid will be just be personal experimental aircraft. Our projected performance and numbers for a hybrid are pretty impressive and always exciting to see how close we come to projections once flying.

 

[MauleSkinner]

Actually, it’s anything but a scrapper from practical sense. It flys better than any c172 and fun to fly. A couple of guys built a couple of hundred hours on it and are now flying for the airlines as a result. No reason it can’t continue. Selling it exposes builder to above average liability risk without practical mitigation, and really only reason for scrapping after flight testing is completed.

Maybe, but it doesn’t appear that way to me.

 

[Redneckpilot]

Please explain more….. what is the difference you mention and why an auto engine cannot be a variable replacement.WW2 aircraft used auto engines. All certified diesels are auto conversions……. What’s your point? Please reference technical data so to get a better understanding.

Examples?

 

[wanttaja]

The listing states it comes with service manual and software and any auto mechanic withe ECM knowledge can work on it…. Just as any modern car.

It's tough enough these days finding an A&P willing to do the yearly condition inspection on an Experimental Amateur-Built aircraft. Going to be tougher with an orphaned auto engine conversion.

Ron Wanttaja

 

[AlphaPilotFlyer]

The FAA isn't a roadblock; certification is a road, and when you get with the FAA, that road is clearly (and I do mean clearly) defined. You build this, you test it this way, for this long, we [FAA] inspect the bits. Developing and certifying a new [for example] large commercial turbofan family, the GE Aerospace GEnx series, cost upwards of two billion dollars.
I'd imagine a well-run cert effort for a simple engine like this to be a small fraction (as a testing calamity won't set you back $15,000,000!), perhaps 50 million.
Your secondary issue is that you'd likely have to buy the engines in bits, and inspect each part, prior to assembly.
$20/hour for fuel, meh. You can (and people do) put E10 in planes such as this, and fly them. Not legally, but likely safely.

Sorry you missed article’s description of main issues project faces…..it is not the certification process at all. It was regulatory leadership preventing us from developing the design in the first place. As a former DER, the cert process is , as you say , outlined after negotiations and such, but one must be able to develop the design first. It sounds as you are ACO related and work with well funded projects using an array of DERs, both company and consultant types, that are essentially developer’s personal FAA once delegated. GA does not usually offer such options for small companies because of cost. It’s mostly a moot point as without FAA leadership at least being responsive, there’s little chance of getting anything meaningful done without resources to apply to FAA effort as well as development.

 

[AlphaPilotFlyer]

I'm surprised nobody has called them out on the operating cost claims.

The performance, fuel flow and airspeed is depicted on posted inflight videos. If you believe we are doctoring the data and IAS, that’s your right. We tried using raw flight video to exhibit said data, including date and times WX conditions can be verified. Our data is not much different from exp aircraft using V8 engines. Depending on prop used and altitude, our cruise performance is 15-23% more efficient (FF/TAS) than original engine. We detailed posted proven data on website as well, but fuel cost assumed on site is a bit outdated but easily corrected with basic math. Again, if we ever decide to offer selling anything, we would post far more specifics as the design will be finalized. We don’t have a detailed spec sheet posted simply because design is still evolving. Our last prop design increased cruise efficiency more than 5% and we will be making more mods, so not sure what final data be if we continue developing but our goal was another 4-6% with prop and planned software mods.

 

[jesse]

True enough. I still see no values listed.
If you reduce the RPM by 50% you’re still at 2700-3000 RPM. These engines in a vehicle cruise at 1500 to 2000 RPM at highway speed.

I’m not relying on a conglomeration of GM chinesium relays and circuit boards to keep the fan turning.
I’ll leave the cutting edge to someone else and cling to my dirty Continental.

Man, you're just a hater. A basic V8 will happily run continuously between 3,000 to 4,000 RPM for thousands of hours. Don't believe me? Just ask the automotive V8 in my boat (which has been doin' it for 20+ years), or the V8 in any Uhaul truck.

Hour for hour, I've had by far more issues with aircraft engines than I have automotive, or really any other modern engine.

 

[Salty]

Our goal was to take this design, learn a lot, and evolve it to hybrid as automotive technology development allowed.

Interesting. That doesn’t sound like the goal that was stated in prior articles and website postings.

 

[kyleb]

Selling it exposes builder to above average liability risk without practical mitigation...

And that would have been better in a production version because???

 

[guest user]

Our goal was to take this design, learn a lot, and evolve it to hybrid as automotive technology development allowed.

Glad to see you on here being able to give your side of this.

I am interested in hearing more about the idea behind your hybridization.

I guess we need to define terms. To me, hybrid means internal combustion and electric.

If this is correct, then you're looking at adding the weight of electric motor plus enough batteries to a general aviation aircraft. Based on your previous work, it will be an existing airframe, and you will probably do a V8 swap there as well. So, before you add the electric part of the equation, you're adding about 225# (your number). Then there is the electric side of things to consider. Batteries are heavy and bulky. Electric motors can be also, especially if they're built to last for an extended period.

So, I'm trying to picture an airframe that would have:
1) The space for your hybrid batteries
2) The payload weight to be able to sacrifice for the constant weight of the batteries / motor while still being functional as transportation
3) The space for batteries / motor that will not negatively affect the CG

I am not saying it can't be done, but I am seeing some pretty significant obstacles and I'd be interested to hear about how you plan to address them.

 

[Dana]

It's tough enough these days finding an A&P willing to do the yearly condition inspection on an Experimental Amateur-Built aircraft. Going to be tougher with an orphaned auto engine conversion.

Diagnosing a fault in the engine electronics will be fun, too. You can get limited information from a portable OBD scan tool, but to really troubleshoot you need the big non portable system that the dealer service shops and better independent garages (but no A&Ps) have. Smaller shops and home mechanics diagnose by throwing parts at it, then drive it and see what happens... not a good idea in an airplane.

 

[Salty]

Glad to see you on here being able to give your side of this.

I am interested in hearing more about the idea behind your hybridization.

I guess we need to define terms. To me, hybrid means internal combustion and electric.

If this is correct, then you're looking at adding the weight of electric motor plus enough batteries to a general aviation aircraft. Based on your previous work, it will be an existing airframe, and you will probably do a V8 swap there as well. So, before you add the electric part of the equation, you're adding about 225# (your number). Then there is the electric side of things to consider. Batteries are heavy and bulky. Electric motors can be also, especially if they're built to last for an extended period.

So, I'm trying to picture an airframe that would have:
1) The space for your hybrid batteries
2) The payload weight to be able to sacrifice for the constant weight of the batteries / motor while still being functional as transportation
3) The space for batteries / motor that will not negatively affect the CG

I am not saying it can't be done, but I am seeing some pretty significant obstacles and I'd be interested to hear about how you plan to address them.

I’d like to see any logic at all that hybrid makes sense for aircraft. It only works in cars in stop and go traffic and hilly terrain. Neither of which occur in aircraft flight. And no, climb /decent doesn’t fit because A, it only happens once per flight, so it’s of extremely limited benefit, certainly not worth hauling extra motors and batteries around for, and B, you don’t get any extra energy out of the decent unless you power a generator, which slows you down, kind of counter productive in air travel, most people want to be going faster. It’s a bit like this

 

[Ted]

A few thoughts in no particular order.

1) LS V8s can run 3-4k RPM for the duration of a TBO just fine. No issues there
2) It will end up being heavier than the IO-360 that it's replacing. Really, not a good choice for a 172, better replacement for a big bore 6-cylinder
3) Flashing the PCM for more power... if you don't think that people have been turning up the boost on turbocharged aircraft engines for decades to get more power and adjusting the magnetos for more ignition advance/more fuel economy, you're delusional. If anything, flashing the PCM is harder/requires more skill/knowledge

But really there's a whole lot more to trying to get an automotive engine certified, some of which just goes to the processes that the FAA still tends to mandate for parts inspection (individual, with no configuration changes) vs. modern machining (six sigma, the process makes for a good part). When Thielert bought engines from Mercedes for their diesels, they needed engines that had no configuration changes. Mercedes threw a fit, saying that wasn't how they did things, changes happened all the time. So they settled on buying all the engines from one day's production, and when those ran out, they bought another day's worth of engines and had a lot of recert to do (part of why the Centurion 4-cylinder engines changed displacement). Continental/Centurion/whoever that entity is now may have improved things. Obviously suppliers change but those have to be approved. It's not simple and it has a lot of supply chain challenges.

Stock ECUs won't pass DO-160 testing or requirements. So you're looking at a new ECU with multiple channels, some form of redundancy, 38999 connectors...

Fuel injectors with O-rings at each side won't pass fire testing, so you have to do something there. I did that testing for the electronic controlled engine I worked on. That was a lot of fun. Scrap cylinder with an injector and fuel rail on it, fuel pressurized and running through the rail. I'm not sure where that program ended up as far as the protection went in production, but I do remember the results of some of the bad ideas that I knew wouldn't work but was told to try anyway. In one case the 2000 degree flame lasted under 5 seconds before the injector and O-rings melted and the fuel all leaked out. The resultant fireball was visible from the 2nd floor reportedly, with a bang that could be felt in the building.

The guys at the test lab were biting their nails the whole time, when the boom went off I just calmly said "I told them that wouldn't work."

The fire really is a big one and something that is really not all that challenging to deal with relative to the other challenges you have, but it is exceedingly important. You lose an O-ring in one of the fuel injectors on your car and have a fire, you pull over and jump out. Car burns to the ground, but usually you're fine. This doesn't work out so well in aircraft, which is why all your fuel hoses are fire sleeved and the injector nozzles are hard lines, and they all use B-nuts. You'd never see this on a production automotive setup - too complex to assemble, weighs too much, etc.

There's more, but as someone who's actually worked on this problem for a living, it's not a simple one and while the FAA's processes don't make things easier, there are also legitimate reasons why the challenges exist.

Few million? That seems a low estimate.

 

[Bell206]

It was regulatory leadership preventing us from developing the design in the first place.

And they did that how? Regardless, while the magazine editor thought the article was factual, I base my opinion on the actual facts of the certification process which I found to be lacking in that article and in other posts. The fact you are moving forward from the 172 project is probably a good thing but it did not fail due to that certification process. Good luck with your new venture.

 

[wanttaja]

1) LS V8s can run 3-4k RPM for the duration of a TBO just fine. No issues there

Based on my analyses of homebuilt accidents, auto engines have a much higher failure rate. About 22% of all accidents involving auto-engined-powered homebuilts were due to mechanical failures of the engine (either spontaneously or due to builder/maintainer errors, vs. about 7% of all accidents where traditional certified engines were installed.

With that said, the problems with auto engines were NOT in the basic engines. Both had roughly the same failure rates due to bearings, pushrods, cylinders, etc. The numbers get even closer when you ignore those due to builder error.

Ron Wanttaja

 

[Salty]

Perhaps he’s thinking hybrid like a train locomotive, which would be interesting, but nobody’s even made it work for a car, so I doubt it’s a good idea after you do the math. Use an efficient diesel automotive engine to turn over a generator and power an electric motor for the prop. Put a smallish battery on board just big enough for a few minutes of emergency flight, and as a boost for max climb scenarios, and make the battery ground chargeable so you start with a full charge.

It’s still carrying multiple motors, but at least it’s not dependent on batteries. And you can have the engine run at high rpm without prop tip speed or gearing issues. But I’m not sure where you fit all the motors, and I forgot about needing a heavy generator to boot. Ok, now I see why it doesn’t work.

I would like to see that as a curiosity. I don’t think it’s the answer to the GA engine “problem”.

 

[Redneckpilot]

Man, you're just a hater. A basic V8 will happily run continuously between 3,000 to 4,000 RPM for thousands of hours. Don't believe me? Just ask the automotive V8 in my boat (which has been doin' it for 20+ years), or the V8 in any Uhaul truck.

Hour for hour, I've had by far more issues with aircraft engines than I have automotive, or really any other modern engine.

No, I’m simply a realist and admittedly an owner of a GM LS equipped product with it’s second LS engine. You can talk to it if you like. Hour for hour it’s been the most problematic POS I’ve ever owned.
I’ve owned more than a few trucks and I can tell you if you’re turning 3000-4000 RPM for any extended period in any truck built in the last 20 years you’re either running 90 MPH or pulling something very heavy everywhere you go.
My opinion is based upon my experience. YMMV.
I’ve also experienced firsthand how a GM automotive V-8 performs in an aircraft.


I simply do not see the value in replacing a reliable, simple engine with an automotive V-8 assembled in Mexico that relies on a complex electronic network with Chinese made components.
That said I can appreciate the argument regarding cost. Aircraft engine parts are way out of reason when you compare them to other engine types. Boat engines are close if not worse.
I do applaud you for doing something.

Still waiting on those examples of WWII aircraft with car engines.

 

[Racerx]

Iirc @AlphaPilotFlyer had stated on this forum previously that the goal was never to get it certified or even stc'd. So I was surprised when the article mentioned those hurdles because I never thought it was the goal.

I'd like to know what the CG looked like with the gearbox and cooler up front compared to a regular K model 172.

I applaud anyone trying to do something different in GA. Maybe one day we'll see commercially viable advancements.

 

[SoonerAviator]

No, I’m simply a realist and admittedly an owner of a GM LS equipped product with it’s second LS engine. You can talk to it if you like. Hour for hour it’s been the most problematic POS I’ve ever owned.
I’ve owned more than a few trucks and I can tell you if you’re turning 3000-4000 RPM for any extended period in any truck built in the last 20 years you’re either running 90 MPH or pulling something very heavy everywhere you go.
My opinion is based upon my experience. YMMV.
I’ve also experienced firsthand how a GM automotive V-8 performs in an aircraft.


I simply do not see the value in replacing a reliable, simple engine with an automotive V-8 assembled in Mexico that relies on a complex electronic network with Chinese made components.
That said I can appreciate the argument regarding cost. Aircraft engine parts are way out of reason when you compare them to other engine types. Boat engines are close if not worse.
I do applaud you for doing something.

Still waiting on those examples of WWII aircraft with car engines.

You mad about the GM v8 or the parts/assembly country of origin? There's nothing particularly complex about the electronics in an LS-engine, either. I've never had any electronics issues our of the 3 LS-engined vehicles I've owned. They've all burned excessive oil because they were AFM-variants, but it didn't affect engine operability in any way. If there was an automotive engine platform I'd trust as an aircraft engine, it'd probably be the LS-series. Ford's Coyote is a close 2nd, but it's a more complex animal with DOHC.