I just read that 90% of piston engined planes can run on 91/96UL avgas... Nice that they are finally getting rid of leaded avgas.
Yep, your right, the R-4360 was even less reliable with its four-row configuration making for insufficient cooling for the back row of cylinders...the back row cylinders being replaced "frequently". The Constellations didn't use the 4360 & once the jets appeared, the 4360 was dropped immediately leaving the 3550 and the lesser engines to keep things going.
--------------------------------------------------------------------------------------------------------------Rick...
With newer emission rules, lower compression ratios got to qualify.
Oddly enough, increased ratios spoiled emission performance!
So lower octane works.
Caterpillar was the first to find lower particulate emissions in diesels due to minimal gap between piston crown and top ring.
That made the piston design complex, as the ring had to stay in place in a very thin groove, on the compression side, and those run at higher ratios than gasoline engines.
Fuel injection gives better performance than carburetors.
And so on.
Now it is a matter of close tolerance machining and building, and tolerances are 10x or more tighter than 20 years ago.
WWII engines were badly made in comparison.
The older piston engines are worn out, and no aircraft above say 300 hp uses them, all have become turbine powered.
Oddly enough, increased ratios spoiled emission performance!
So lower octane works.
Caterpillar was the first to find lower particulate emissions in diesels due to minimal gap between piston crown and top ring.
That made the piston design complex, as the ring had to stay in place in a very thin groove, on the compression side, and those run at higher ratios than gasoline engines.
Fuel injection gives better performance than carburetors.
And so on.
Now it is a matter of close tolerance machining and building, and tolerances are 10x or more tighter than 20 years ago.
WWII engines were badly made in comparison.
The older piston engines are worn out, and no aircraft above say 300 hp uses them, all have become turbine powered.
Once turbos matured, their fuel consumption weight/HP-Hr was as low as piston engines. Their fuel was very much cheaper. Their maintenance costs (rings, valves, rod-bearings, sparkplugs....) was VERY much lower (whereas maintenance on the over-blown piston engines was going up and up...).
Aircraft engines always run as much compression as the available fuel allows, because they need power/weight. In the early 1930s this might be 6:1. Late 1930s, improved fuel suggested 7:1 or 8:1 AND very significant supercharger pressure. A 1.5 bar intake pressure with 8:1 compression is like almost 12:1 compression in terms of power and knock. This was the era of >100 octane.
The sleeve-valve engines WWI to WWII (into the 1960s as replacements) were a side-track. They worked very well, but (oddly) not better.
https://en.wikipedia.org/wiki/Sleeve_valve
The concept got a boost from an important paper which suggested that poppet valves were not going to get better and sleeves would--- this seems to be wrong. Nevertheless Tizard and Ricardo prototyped a very thirsty engine, R-R Crecy, specifically to climb as fast as possible to intercept bombers coming over England. The post-war report is interesting, and sheds light on why good ideas go astray. Crecy was not a front-burner project, in a time of shortages, and some now-obvious flaws were neglected.
But the most practical aircraft sleeve valves were from Napier and Bristol.
https://en.wikipedia.org/wiki/Napier_Sabre
https://en.wikipedia.org/wiki/Bristol_Aeroplane_Company#Bristol_Engine_Company
One odd link: After WWII when a new engine company was started to make both Ferguson tractor and Standard/Triumph car engines, they got the old sleeve-engine building WITH machinery. Normally small engines don't get replaceable liners because the grinding cost is too high.... but the idle sleeve grinders begged to be put to work. Sleeves on the tractor engines made much sense, but sleeves on sedan engines are almost unheard-of.
To get back on track(?) there is the British RCV series of "SP" model engines.
https://www.baronerosso.it/forum/attachments/aeromodellismo/815d1098268317-motori-rcv-info-rcv.pdf
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Thanks for the insight. I wasn't aware of the supercharging.
For aircraft service, not only piston engines in general, but especially sleeve valved ones were prone to lead into a dead end. I always was puzzled about what this technology was good for. Their internal friction added the intrinsic piston movement and the rotating and oscillating motions between two pairs of surfaces 😳.
Yes, let's go back to track now. Let's design a 20 feet blade lawn mower powered by a R-4360 engine 🤣🤣🤣.
Best regards!
For aircraft service, not only piston engines in general, but especially sleeve valved ones were prone to lead into a dead end. I always was puzzled about what this technology was good for. Their internal friction added the intrinsic piston movement and the rotating and oscillating motions between two pairs of surfaces 😳.
Yes, let's go back to track now. Let's design a 20 feet blade lawn mower powered by a R-4360 engine 🤣🤣🤣.
Best regards!
Toyota D-Turbo has a design that has turbo boost start at fast idle.
Internal combustion engines for cars went like this:
Both Side Valve, then one each side and over head, then both overhead...still push rod.
Then OHC, DOHC, and more than 2 valves per cylinder.
In parallel, carburetor was succeeded briefly by throttle body (single point) and later multi point injection.
Interestingly, the block and crank have not changed much, pistons have.
So you can say it was an evolution of the combustion chamber for the most part.
A lot of credit goes to Jimmy Carter, for imposing CAFE and emission norms, that led to all this development.
Internal combustion engines for cars went like this:
Both Side Valve, then one each side and over head, then both overhead...still push rod.
Then OHC, DOHC, and more than 2 valves per cylinder.
In parallel, carburetor was succeeded briefly by throttle body (single point) and later multi point injection.
Interestingly, the block and crank have not changed much, pistons have.
So you can say it was an evolution of the combustion chamber for the most part.
A lot of credit goes to Jimmy Carter, for imposing CAFE and emission norms, that led to all this development.
Poppet valve-works have significant friction too. Ever turned-over a V-8 by hand? Even with plugs out at 10RPM it is hard work, and maybe half of that is the valvetrain.
The historical survey above omits "automatic intake valves" which were VERY popular even into WWI. A light spring let the intake valve open at about the right time. A slight loss of intake pressure and some limitation on RPM avoided a lot of mechanical complication. Chain-driven overhead valves were common on race cars long before pushrods got popular. The dominance of the Flathead in automobiles was due partly to simplicity and mostly to quietness- few of us remember days before hydraulic lifters or small finely-balanced OHC rockers. OHV engines used to CLATTER. Flatties had less valvework all enclosed in cast iron. OTOH, flatheads were "never" used in aircraft or US farm tractors. (The Fordson tractor is the exception which proves the rule; except there was another based on the Chrysler Straight Eight flathead sold in small numbers). (And my grandfather's partner carved the propeller for a Plymouth Six powered "family airplane" prototype which finally went down in Alaska.)
With all the "fun" and friction and noise of poppet valves, the attraction of sleeve valves made sense. Lots of car companies tried it, some for quite a long time in that era of change. The usual cheap 2-stroke is a sleeve without rotation. That RCV model engine is a sleeve without reciprocation. The 40,000+HP engine on container-ships is a cylinder-ported 2-stroke from Sulzer and MAN designs. Let's forget the Winton/Detroit Diesel bastard.
Cranks have evolved in less obvious ways. I had a 1930s Willys Four which had innovative (for the time) oiling. My 2002 Honda Four has TWO extra bearings of much larger diameter, and instead of bearing caps it has a full 'girdle' to hold the bottom end together at much higher RPM than the time the Willys threw its guts on the road. Such RPM were impossible on old bronze and babbit bearings, had to wait through several generations of shell bearings. Vave-springs too: MG wanted to break 120(?)MPH. They got on the track, 110MPH, broke a spring. They made a new set, went 113MPG, broke a spring. Took about 5 different experimental heat-treats to hold 120MPH all the way around Brooklands.
OMG!! I started this on the Win7 desktop, got distracted, got my new Win10 flaptop going, and this draft was waiting for me!
Take it out and hang it on the plane? No, there's a lot of little-bits to transfer-over, and a lot of details to triple-check.
Hey! Great old film about unboxing an engine! Your B-17 lost a motor. One day, oh boy! a box! 4'x5'x5', so not an Allison. It's a R-1820! Wright designed it and built as many as they could, but actually Studebaker made a whole lot of them.
Take it out and hang it on the plane? No, there's a lot of little-bits to transfer-over, and a lot of details to triple-check.
"Good grounding reduces noise in the aircraft radio systems" Of the cowling structure to the engine. I wonder how long it took them to root cause that one, to needing 4 ground straps!
Actually, I think power tools started becoming common only after the mid-50s.
And most factories, and even the brands, are no longer in existence, or sold to Chinese or other entities.
Porter Cable is practically gone, old rivals Stanley and Black & Decker have merged. Wolf is gone, survives as Ralli Wolf in India, with Rallis having sold out long back.
Bosch sold their power tools business, along with trade mark rights to use the Bosch name on power tools, to their long time Chinese supplier.
And so on.
We had a carpenter who did the work at our flat in Delhi, at age 54 he did most of the work alone, and said the body must be used as much as possible, or it goes sticky.
Hand saw, hammers, no power tools. 1987.
And most factories, and even the brands, are no longer in existence, or sold to Chinese or other entities.
Porter Cable is practically gone, old rivals Stanley and Black & Decker have merged. Wolf is gone, survives as Ralli Wolf in India, with Rallis having sold out long back.
Bosch sold their power tools business, along with trade mark rights to use the Bosch name on power tools, to their long time Chinese supplier.
And so on.
We had a carpenter who did the work at our flat in Delhi, at age 54 he did most of the work alone, and said the body must be used as much as possible, or it goes sticky.
Hand saw, hammers, no power tools. 1987.
One more thing, power tools need regular maintenance and a power supply.
Try finding spare armature or even brushes for a not popular model.
And think how long the power cords would need to be, working on a plane in a grass strip in the middle of the Pacific.
Even portable generators did not come along till much later.
Or even the mowers we are discussing.
Makes you think, does it not, how things have changed within less than a century?
Try finding spare armature or even brushes for a not popular model.
And think how long the power cords would need to be, working on a plane in a grass strip in the middle of the Pacific.
Even portable generators did not come along till much later.
Or even the mowers we are discussing.
Makes you think, does it not, how things have changed within less than a century?
What about DeWalt, Makita, German manufacturer Metabo etc.? Only a month ago I bought a Metabo TS 254 table saw which turned out to be delivered to me right from their factury at Nuertingen, next to Stuttgart.
Best regards!
The most efficient lawnmower has one intake and one outlet valve, is relatively silent and runs on grass.
It is common now that the factory is the warehouse now, the finished goods are shipped in from outside, and inspected, if at all.
The other issue is that the younger workers are not willing to work on the shop floor.
So your workers are ageing, slowly retiring, not enough new people coming as replacements.
DeWalt was the heavy duty version of Black & Decker, for continuous use at site by contractors.
Now, it may been sold, or whatever.
Similarly, check the IP addresses for Metabo, they might tell you what is going on, apart from the net.
Makita and Ryobi are still Japanese companies with factories mostly outside Japan, as per my long ago information.
The other issue is that the younger workers are not willing to work on the shop floor.
So your workers are ageing, slowly retiring, not enough new people coming as replacements.
DeWalt was the heavy duty version of Black & Decker, for continuous use at site by contractors.
Now, it may been sold, or whatever.
Similarly, check the IP addresses for Metabo, they might tell you what is going on, apart from the net.
Makita and Ryobi are still Japanese companies with factories mostly outside Japan, as per my long ago information.