I Believe We Are Doing This Wrong

[Ed Haywood]

The homebuilders have been doing it since the 1930s. No conversion has been spectacularly successful. In fact, many fool with a conversion for a long time, trying to make it work well and safely, and ultimately give up and stick a Lyc on the nose and go flying. I've been there, installing a Subaru in a Glastar. Spent a lot of time working the bugs out of it, and even then it had shortcomings.

Exactly my point. I like my Lyc.

 

[Bell206]

Neglect, mostly. The manufacturers recommend 500-hour inspections (400 hours for Bendix/TCM) but most are run until they fail. In flight. Which is insanely stupid, in my view.

FYI: my question was in reference to some "new" certification standards for e-mags that the old conventional mags supposedly can not pass.

 

[ateamer]

Neglect, mostly. The manufacturers recommend 500-hour inspections (400 hours for Bendix/TCM) but most are run until they fail. In flight. Which is insanely stupid, in my view.

When I bought my RV-8, I noted that the engine log included an entry at 500 hours for an inspection of the Slick mag (the other ignition was a Light Speed Plasma electronic). The entry said it checked OK. At around 850 hours I got a couple bad mag checks (excessive RPM drop, noticeably more roughness during normal operation than normal) and eliminated other possible sources. It went in for condition inspection right then anyway, so we pulled the mag and sent it to a repair station for IRAN.

The repair station owner called a couple days later and said that every part in the mag was beyond service limits. He said that no way could a proper 500 hour inspection have been done, because some of the parts were so worn that they had to have been well-worn by then.

Looking back at the log entry, it just said “500 hour mag inspection OK”, signed by the previous owner. No reference to who actually did the inspection or what guidance or standard was followed (if any). Almost certain that the inspection was done by the owner who didn’t exactly have the mechanical chops to be doing that. So I’ll chalk that up to neglect, because to my mind a well-meaning but unqualified person inspecting a critical component is as bad as a qualified person not doing the inspection.

 

[Dan Thomas]

Well, they put them in street cars (Ferrari, McLaren) that cost a lot less than a new Piper M350 or Cirrus SR22.

That doesn't tell me what the engine costs. The engine in a Cirrus is maybe $80k new. What is the airplane? $700k? The engine/car ratio won't be the same. The car isn't full of expensive certified avionics. And the car's manufacturer liability won't be nearly as much as the airplane's. The car's engine will be a bigger chunk of its selling price.

 

[StraightnLevel]

That doesn't tell me what the engine costs. The engine in a Cirrus is maybe $80k new. What is the airplane? $700k? The engine/car ratio won't be the same. The car isn't full of expensive certified avionics. And the car's manufacturer liability won't be nearly as much as the airplane's. The car's engine will be a bigger chunk of its selling price.

It can tell you enough to make a comparison. The McLaren Artura starts at ~$250K with a ~600 hp V-6 engine and a hybrid boost system for another 100 hp or so. The car itself is mostly carbon fiber, so the V6 is clearly not the majority of the cost. Even if it's a full 1/3 of the selling price (which seems very unlikely for any sports car), it would be about the same price as the Cirrus engine, which has only about 1/3 the power output of the McLaren.


....and now, here I sit asking myself why I'm looking at planes instead of another car, again.....

 

[SebIp]

It can tell you enough to make a comparison. The McLaren Artura starts at ~$250K with a ~600 hp V-6 engine and a hybrid boost system for another 100 hp or so. The car itself is mostly carbon fiber, so the V6 is clearly not the majority of the cost. Even if it's a full 1/3 of the selling price (which seems very unlikely for any sports car), it would be about the same price as the Cirrus engine, which has only about 1/3 the power output of the McLaren.


....and now, here I sit asking myself why I'm looking at planes instead of another car, again.....

Cause you can only “fly” a car once.

 

[StraightnLevel]

Cause you can only “fly” a car once.

...then perhaps you're doing it wrong!

 

[Pinecone]

Every engine that gets used on a race track gets run at 100% the majority of its operating life. Generally, they are either derated intentionally or have relatively short rebuild intervals.

That was the point. No 2000 hour TBOs.

 

[Pinecone]

Well, they put them in street cars (Ferrari, McLaren) that cost a lot less than a new Piper M350 or Cirrus SR22.

No, they put in a high performance street engine. Not the same engine as an F1 car.

And until the rules changes, F1 cars would use 2 - 3 engines PER race weekend. And that race is a max of 2 hours, and many did not make that.

 

[Pinecone]

But look at the cc/HP chart I linked above. A top fuel dragster engine gets torn down and rebuilt after every run -- not practical for our purposes -- but it puts out 1 HP per cc. Those "loafing" car engines put out 1 HP per 15cc. An IO-360 @ 200 HP is just under 1 HP per 30cc. Likewise an IO-540 (8.85L) rated for 300 HP. They're working half as hard at peak as an auto engine.

But that auto engine runs at a small fraction of the maximum power. An aircraft engine runs at 65% of rated power or higher for most of its life.

 

[StraightnLevel]

And until the rules changes, F1 cars would use 2 - 3 engines PER race weekend. And that race is a max of 2 hours, and many did not make that.

Those rules that allowed multiple engines for qualifying, practice and races are decades old. Now, they are only allowed three engines per season, with 24 race weekends.

The street car engines are slightly different, but you're still talking about 600 hp designed for reliability at full power for the same or less $$$ as a 200hp Lycoming. And the engines in McLarens and Ferraris don't have the sort of volume advantage that we see in a Mustang or Corvette engine.

 

[tspear]

Those rules that allowed multiple engines for qualifying, practice and races are decades old. Now, they are only allowed three engines per season, with 24 race weekends.

The street car engines are slightly different, but you're still talking about 600 hp designed for reliability at full power for the same or less $$$ as a 200hp Lycoming. And the engines in McLarens and Ferraris don't have the sort of volume advantage that we see in a Mustang or Corvette engine.

Now I am kinda curious, and searching online did not get me an answer. I recall watching multiple car shows over the years (ok, a decade ago when I used to watch Top Gear along with others), where they discussed and test drove hyper cars on a semi-regular basis. I think, every example the engines were all based on mass production engines which were "tuned", or were decades old designs that have been incrementally improved.
I now wonder what is the current state (and how my recollection holds up too!).

Tim

 

[StraightnLevel]

Now I am kinda curious, and searching online did not get me an answer. I recall watching multiple car shows over the years (ok, a decade ago when I used to watch Top Gear along with others), where they discussed and test drove hyper cars on a semi-regular basis. I think, every example the engines were all based on mass production engines which were "tuned", or were decades old designs that have been incrementally improved.
I now wonder what is the current state (and how my recollection holds up too!).

Tim

I don’t think that’s true for McLaren, Ferrari, Porsche (though you could make a case that Porsche volumes are high enough to qualify as “mass-produced”). They all make their own engines for their street cars, and they are specific to their cars. In fact, I’m fairly certain that Ferrari have always built their own engines for all of their cars, and they are not up-tuned versions of anything else. They are also a supplier of engines for other Formula One teams, so their starting point for street cars is most likely to be 8-10 year old F1 technology.

Lamborghini certainly uses some Audi design basics for their Huracan engine range, but even there it seems that they’ve done a lot more than just bolting on some parts and tuning it aggressively.

 

[Pinecone]

In the past, some higher performance street cars used street engine based power plants.

The DeTomaso Pantera used a Ford 351 Cleveland. The BMW M-1 used an engine based on the "big" six, used in the M-5 and M-6 at the time.

Most all Ferraris use engines designed and produced by Ferrari.

As for F1, they are now 4 engines per season (without a penalty), but even so, that is 6 race weekends. 3 practice sessions, that if they run the full time is about 4 hours. Qualifying, which is max of 3 sessions, where they run a few laps a couple of times, but say another hour. And the race for max of 2 hours, but most are more like 1.5. So each weekend is a max of 7 hours. Time 6 is 42 hours. So the engine, if it makes it the required time is done in less than the time between oil changes for an aircraft engine.

 

[Dave Palacios]

Consider this:

What other modern engines use magnetos instead of electronic ignition?
What other modern engines run on leaded fuel?
What other modern engines use carburetors instead of fuel injection?
What other modern engines use manual mixture control instead of closed-loop automated control?
What other modern engines must run at air densities from below MSL to 25,000+?
What other modern engines are air/oil cooled instead of water-cooled?

The list goes on and on. GA has boxed itself into a corner with our application requirements. As a result, we're on a technological island all by ourselves, with no other industry helping to share our development and tooling costs.

As a point of comparison, Jasper is a company that rebuilds automotive and marine engines, differentials, and transmissions. Every year, they rebuild 65,000 engines and 75,000 transmissions. Compare this to the GA market as a whole; there are only ~ 200,000 total GA aircraft, so if each one gets a rebuild every ten years (unlikely), it would still be less than 1/3 of one automotive rebuild company's volume.

https://www.jasperengines.com/about/about-remanufactured-engines/ [Full disclosure - I got a rebuilt V-10 from Jasper about15 years ago. It ran flawlessly for more than 100,000 miles until I sold the SUV it was in - longer than the OE engine had survived.]

apples and oranges