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Aircraft certified motor vehicle engines. Is there a niche for them


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Many years ago Porsche made an aircraft certified engine from their 3.3litre engine. Only one aircraft manufacturer used it. It was unusual in that it had only one control, a power wanted control. Everything else was automatic. Mooney placed it as an Porsche engined Mooney. It was however slower than the Lycoming engined Mooney. Who buys a slow Mooney. Not many people. One was bought by a Porsche fanatic, no aircraft licence, but it was just to sit in his garage. Only a handful were made. Porsche offered to refit all Mooney Porsche with Lycoming engines.

But today with modern 2 litre engines reliably putting out 250BHP, with excellent fuel efficiency, could one of these engines be turned into an aircraft engine? Would they be cheaper? Would they be a dream to fly like the Porsche Mooney is? Actually 40%of the world fleet is in Australia!

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The Porsche flat sixes were troublesome enough in their cars, let alone putting them in an aircraft. They had many design failings.

Top that with a manufacturer who ended up not supporting the aero engine design, because they went on to "newer and better design" engines, and you're left with an expensive orphan.

A very good assessment of where Porsche failed with aero engine design, is in the link below.

 

http://www.seqair.com/Other/PFM/PorschePFM.html

 

There's no doubt automotive engine design has improved greatly in the last 25 years. But auto manufacturers are prepared to support their engines for about 15 years, and that's not a long time.

Then there's the perpetual weight problem. Despite car manufacturers concentrating on weight decreases in recent years, the engine has received the minimal amount of weight reduction.

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I'm a fan of the Diamond Aircraft engines, Austro Engines. (Diesel ICE, not the Wankel's)

I believe they were developed from a Mercedes engine.

At one point they had a 3 cyl 120 hp engine.....which (on jeta1 fuel) would have been nice.

https://en.m.wikipedia.org/wiki/Austro_Engine_E4

https://en.m.wikipedia.org/wiki/Austro_Engine

https://www.austroengine.at/

I wish they would release these into the experimental market.....

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The Porsche PFM article seems one sided to me. The Mooney 201 only had one electric system but later IO540 Mooney's had two. Reliability seems good on the still flying examples and parts are available from Porsche engine spare parts. It was heavier, that kills any aircraft upgrade.

I have flown one. It was so smooth, a joy to fly.

The latest petrol engine cycles are similar to diesel engines, maybe a dual fuel engine would be great.

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If you are interested in this topic, you might like to check out Raptor Aircraft on Youtube if you haven't already. Raptor Aircraft is a guy named Peter Muller, an Aussie living in the USA. He has designed a high-performance and very spacious 4/5 place canard pusher aircraft pretty much from scratch (although it looks a lot like the Velocity), and its power is provided by the Audi 3 litre twin-turbo diesel V6. With a reduction drive of course - pretty much essential for any car engine to drive a propeller. He has been working on this for 4 years or so and is on the brink of first flight - I think the test pilots are booked for the end of July.

 

It's an interesting story. Peter had no background in aircraft design (he's a computer nerd like me), but when he did his training for his pilot licence some years ago he was taken aback by how cramped and uncomfortable small aircraft were (are), and how expensive. He reckoned that if he could buy a high-end car like an Audi for (say) $60K or so, why was a decent aircraft 4 times that price, or more? After looking around he decided the Velocity was the closest to what he was looking for, but it still didn't tick all the boxes. So he decided he would design and build his own. He has made a lot of mistakes, but has been completely open about all the failures as well as the successes, with 2 videos per week almost every week since the project started. He does intend the Raptor to go into production, and has hinted at some negotiations which have taken place, but I'm guessing nothing will be revealed until it has flown. I stumbled across the channel about 18 months ago and have been following the ups and downs ever since - I find it quite compelling, and I certainly admire Peter's persistence and tenacity.

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.............................................................................. He reckoned that if he could buy a high-end car like an Audi for (say) $60K or so, why was a decent aircraft 4 times that price, or more? After looking around he decided the Velocity was the closest to what he was looking for, but it still didn't tick all the boxes. .......................................................

 

Is called VOLUME - all aircraft are essentially hand built. Check out the price of a hand built car, that may only sell 20 -50 units per year - cost will be similar to a small aircraft.

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Of course. Those are Peter's ideas, not mine. And although I respect his persistence with this project, I think the chance of him ever getting it into production is probably about 5% or thereabouts. But I'd be quite happy if he proves me wrong on that.

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It's like inventing a new mouse trap, the pests are still with us after a zillion fancy types of mouse traps been invented but the good old wood Spring .50c trap does the job! Two things will always hold back new engine designs, reliability and resale, the latter often the biggest issue!

Sometime ago there was an RV8 for sale (in the States) that had an oddball rotary donk in it, sat on the market for ages, finally sold for peanuts and re-engined wth a proper A/C engine, it's value would have increased instantly!

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Sauer and Limbach do some European certified VW based engines.

I think the chocolate(?) blimp that used to run around Melbourne a few years ago had Limbachs.

There are lots of auto engine based non-certified engines.

 

Raptor: an accident looking for a place to happen I think. Way too many half-assed fixes on the run, and mostly in the flight controls. I find it very difficult to watch his progress, absolutely messed up "Americanized" Aussie accents turn me right off.

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If the Raptor had a lycoming or Continental 310hp engine it would be one less unknown. If it flies I feel it will struggle to reach 150knots, to heavy and to fat.?

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IF you want to FLY, just use a proven engine. IF you want to fiddle and experiment it's your choice. I believe an aero engine should be purpose designed from the ground up, so to speak.. ALL piston engines are inclined to self destruct compared to the turbine types. I like radials because of the way they rumble through the sky and the way they are not stressed in cruise. They must be well made unless you don't care about long trips. I'd fly behind an Anzani and they are very unreliable but I'd pick my aerodrome and day and I wouldn't be using it for RPT. It would be for the experience.. .Nev

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I don't think car engines will get a lot lighter because manufacturers aren't going to spend too much on yesterday's tech. The will be looking at sharing costs of battery development etc instead. Even if hydrogen becomes popular they wouldn't worry about weight to much since for a regular car, it isn't a big difference is n total weight.

 

As far as existing engines, I quite like the air cooled VW conversions. If I ever finish my current build and want to punish myself further, I think id build a sonex with a VW next ?

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I rallied VW's in a past life so I'm familiar with Hitler's REVENGE. Looks like an aeroplane engine but it isn't. There's a lot of development gone in but it's compromised by remnants of the original. as nearly always happens. Nev

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There are a lot of VW based engines flying. The good ones are those that don't offer 100hp, but are providing a reliable engine for light aircraft such as the Corby Starlet. One step up from them is the Jabiru, Three steps up, at least coastwise is the Rotax.

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IF you want to FLY, just use a proven engine.

 

I tend to agree. For a start, the mission of car engines is so different from that of aircraft engines. Most cars spend most of their life loafing around at (I'm guessing) less than 50% power. Aircraft engines spend a lot of theirs at 75% or greater. I don't even really like the look of Rotaxes - don't like reduction drives much. Yes I know there are tens of thousands of them out there, but it seems to me that the main reason "mainstream" aircraft engines still look the same as they did about 50 years ago is because they WORK.

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I looked extensively into VW s for planes over many years. I've worked on ,many and been involved with one that was rallied. Owned 2 as well (one eventually learns). We always referred to them as ("Hitler's Revenge') They LOOK a bit like an aero engine But no matter how hard you work, any remaining original bit will ruin it for you. The cases are weak the inlet port(s) shouldn't be on the top the heads shouldn't be siamesed Cast iron cylinders?? How do you attach a prop so it will stay on? Cranks break, rods are weak, .valve guides are too short, rocker studs pull out.. No doubt they have their adherents. Good luck to them. Nev

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The Subaru 1800 / 2200 /2500 / 3300 are well proven auto to aero conversions. Huge hrs logged,

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Fuji Heavy Industries (now the Subaru Corporation) was originally formed from some of the remnants of the Nakajima Company after WW2.

The company has been an aerospace manufacturer for many years and designed the Subaru Boxer engine along aircraft engine design lines - but the Boxer engine has no aircraft pedigree.

 

What is worse, is that because Subaru is a relatively low-production manufacturer - and also because Nissan formerly owned a sizeable portion of Subaru - many components of the Subaru vehicles and engines are made by Nissan.

Now, Toyota is a major shareholder in Subaru and they also supply components to Subaru under contract. In addition, Subaru has had a recent scandal where unqualified employees were allowed to oversee QC.

All of this doesn't go well as regards producing consistently high quality products.

 

The Subaru diesels had major problems with crankshaft breakage (now cured, apparently), and the petrol EJ25 Boxer engines suffered regular failures due to leaking head gaskets - and the pistons and rings can also give trouble.

Because Subaru chose to use cast hypereutectic aluminum-silicon pistons containing a high level of silicon (12%), this gives their pistons a low coefficient of expansion, and high strength. Their aim was close-tolerance fit pistons.

But those features also make the pistons quite brittle - and they won't tolerate any detonation or pinging, or they will break ring lands. In addition, the oil rings are prone to becoming blocked with carbon, resulting in increased oil consumption.

 

The bottom line is, there's a small hard-core group of Subaru and Boxer engine lovers out there - but overall, the Subaru Boxer engine has no higher reliability than any other automotive engine, and in fact can suffer from numerous problems.

 

I personally believe Honda has the best of the Japanese car engines, and Viking appear to believe that, too. But I believe Viking make a big error in sourcing engines from wrecked cars, which doesn't give one a comfortable feeling.

Aeromomentum appear to believe the Suzuki engines are superior - but more importantly, Aeromomentum use all new components, and build their engines utilising the components that are best suited to aircraft use.

Either way, both are still up against the perpetual weight penalty problem associated with purely automotive engines being altered for aviation use.

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True. The 3 cyl Anzani wasn't much of a thing but you didn't have a lot to choose from back then... They also made an Outboard motor (which I have the engine part from) 2 cyl water cooled 2 stroke. If anyone needs it I don't need much for it but I'm not interested in posting etc Nev

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Then there's the perpetual weight problem. Despite car manufacturers concentrating on weight decreases in recent years, the engine has received the minimal amount of weight reduction.

 

you would be surprised,

an modern alloy block V8 is about the same weight as an old iron 4 cylinder.

especially with the internals being forged and alloy too.

 

I tend to agree. For a start, the mission of car engines is so different from that of aircraft engines. Most cars spend most of their life loafing around at (I'm guessing) less than 50% power. Aircraft engines spend a lot of theirs at 75% or greater. I don't even really like the look of Rotaxes - don't like reduction drives much. Yes I know there are tens of thousands of them out there, but it seems to me that the main reason "mainstream" aircraft engines still look the same as they did about 50 years ago is because they WORK.

 

hmm, only vehicles I can think of that get set to 100% or cruise at 75% are boats, where weight isn't an issue.

 

Or Jet-skis, most are running a motorcycle derivative engine with the revs reduced. the main issue is cooling, they normally use pressure and water from the jet pump. the exception is Seadoo... which is BRP (aka Rotax) they run a closed loop system... and have reliability issues because of it

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I reckon the alloy Chev V8 has real aero potential. There's enough of them around for the right bit's to be known. Too big for our purposes though.

IF I was building a new plane it's not easy to decide on what engine. RV's are well suited to the Lycoming although I don't know just how good the "Superior" is. Nev

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