High Octane Fuel and Cooling

[Shortround6]

There were numerous better GA engines in existence, like Argus, Hirth, Kinner, Jacobs, DH Gipsy. The latter was cleared to 1500 hrs TBO in 1944 in wartime conditions with wartime oils and mostly used fuels well below 100 octane with competitive sfc. My favourite would be a 5- to 7-cylinder radial with turbocharging, liquid-cooling, direct injection and sleeve valves.

I am not sure what you are after here, or what real data you may have.

In 1944-46 most, if not all of these engines ran on fuel well below 100 octane including the Continentals and Lycomings.

Continental and Lycoming took over a good part of the GA market because they offered a range of decent engines at a good price with wide spread product support (parts). The use of common cylinders between some of the 4 and 6 cylinder models was nothing new and DH did the same thing with some of the Gypsy Major and Gypsy Queen models.

Some of the attributes of one engine type or another get a bit lost on most GA planes. Once you go to side by side seating a narrow engine doesn't matter much any more. View over the nose does and while the flat engines are wide the are also shorter than the inline engines ( A 6 cylinder Lycoming can be noticeably shorter than an inline 6). I would note that both Continental and Lycoming built Radial engines all the way through WW II and Continental built larger radials under license.
Hirth engines may have been nice but were rather expensive ( and mass production wasn't going to bring the cost down to be competitive) because of some of the design "features", like the ball and roller bearings on the crankshaft which meant a multi-piece crankshaft. In the 1930s with plain bearings of questionable quality at times this may have been a good feature, Post war plain bearings were much improved and the Hirth crankshaft, while elegant, wasn't needed.

During the 1950s a number of companies built supercharged GA engines fitted with reduction gears. Power per unit of weight was good but purchase and overhaul expenses were high and most were eventually replaced with larger, slower revving non-supercharged-un-geared engines.

The engine you propose, while technical interesting, would be absurdly expensive for most General aviation use.

Fuel injection is becoming much more common but turbo-charging is mostly used by planes with pressurized cabins. US regulations (i believe ?) call for pilots in un-pressurized aircraft to wear an oxygen mask above 12,000ft?

No one yet has shown if the sleeve valve was actually cost effective. Many of the problems it was supposed to solve were solved in other ways during the time it took to develop.

How much more do you spend on the engine so you can burn a bit lower grade of fuel? How many hours (gallons of fuel) before you break even?

 

[gumbyk]

There were numerous better GA engines in existence, like Argus, Hirth, Kinner, Jacobs, DH Gipsy. The latter was cleared to 1500 hrs TBO in 1944 in wartime conditions with wartime oils and mostly used fuels well below 100 octane with competitive sfc. My favourite would be a 5- to 7-cylinder radial with turbocharging, liquid-cooling, direct injection and sleeve valves.

I've flown behind two of these 'better' engines, so these are the only two I can comment on.

the Kinner was affectionately referred to as the 'Kinner Time-bomb' what does that say for its reliability? 540 cubic inch, producing 160 hp - not exactly efficient.

The Gipsy is 370 cubic inch, producing 140 hp at take-off power - compare that to 200 hp for a lycoming IO360. Inverted engine technology means that your oil consumption is, by todays standards unacceptably high.


Incidentally, I have one customer who has an approved TBO extension to 4000 hours for their fleet of C-172's with IO-360's.

 

[Shortround6]

The Jacobs also was known as "the Shakin' Jake" among others and this was in it's 757 cu in version. Later 830 cu in and 915 cu in were unlikely to be any better. These were all 7 cylinder engines. The Jacobs may have been innovative in it's day, well made and reliable but customers were also demanding comfort and less vibration.

It also had a slight problem with vision over the nose in single engine private planes.

Granted they did make almost 1200 of these Cessnas but they were pretty much replaced by the Cessna 180 and later the 185

The trike gear planes were safer to land and take-off.

 

[GregP]

They aren't safer to land and takeoff, you just have to get trained. Doing it all by yourself is not recommended.

And if you are truly landing off-airport at unimproved places, the conventional gear is MUCH safer and more useful since there is no nosewheel to snap off. As an added bonus, there is much less tendency to swing on grass and other off-airport locations.

All the nose gear does is make for less training in aircraft control during takeoff and landing, which was the post-war point ... improved sales.

 

[FLYBOYJ]

They aren't safer to land and takeoff, you just have to get trained. Doing it all by yourself is not recommended.

Greg, statistically they are, and in my experience, they are...

Some tail draggers you are flying them the minute the prop turns. I have flown 180 HP Super Cubs and C172s and 182s, the latter are EASY. I love the Super Cub but it will bite you a lot quicker than a 172 or 182 will any day of the week and it doesn't matter how much training you have.

 

[GregP]

That is true as a group, tricycle versus conventional gear. The only "bush planes" flying with nosewheels are landing and taking off on prepared strips or very smooth ground. The real "off airport" stuff is still for conventional gear only. I suppose as the world gets tamer and tamer that, at sometime, all places will be "prepared." If I'm boring holes in the sky a C-172 is fine and even enjoyable. If I want to go take on a challenge, I'd rather have a C-170 or C-180 myself. The C-180 is my favorite GA plane to fly, though a C-185 is the same with more power.

Let's say my reply was from the point of view of a guy who has flown both and chooses the tailwheel over the nosewheel when possible, without saying anything bad about the nosewheel.

If I wanted a light "go anywhere" fliver, and also could afford it, it would probably be a Just Aircraft Super STOL or a Preceptor STOL King. Go look at any video of either one and tell me they don't look like pure fun! For a REALLY big Super Cub, go watch a video of the Sherpa aircraft. They even have one with a turbine! It's like a Super Cub the size of an Otter.

Nothing to do with warbirds, but very entertaining to think about. Another favorite is the Aircam. Great videos!

Here's one:


View: https://www.youtube.com/watch?v=0zDo7hkmCNY

Time for a scone ...

 

[fastmongrel]

Didnt Porsche try to break into the aviation market with modified 911 Boxer engines whatever happened there seems to me it would have been an ideal engine for unleaded use.

 

[Shortround6]

Porsche tried at least twice to get into the aircraft engine business. Once in the 50's with the then current flat 4 with push rods, both in regular engine and helicopter engine form (the latter had fan cooling) and later (60's/70's ?) with the flat six. some were used in airships/blimps.

With today's insurance and certification costs it might not be that profitable. That and the Porsche engines rather need reduction gears which add to cost and maintenance. I mean Lycoming makes a rather decent, if old, 5.9 liter 4 cylinder engine, that is a lot of torque/power at an rpm that doesn't need a gear box.

 

[Milosh]

Isn't the VW flat 4 a Porsche design?

 

[Shortround6]

It is and the 1950s Porshe engine wan't that far removed from the VW engine, especially in the very early 50s. Porsche went to larger displacement sooner than VW. But there is only so much you can do with a 1.6 liter aircraft engine. See modern (or 60s-80s) conversions of VW engines for aircraft use. Not a bad replacement (?) for a Continental A40 engine but not anything much larger.