OK, I was at my Czech Swiss mechanic ( Mom and Dad brought together by events in Europe last world war or so..) having my car looked at after the marathon cross country run… and I get shown this U-Tube of a ‘ball motor’.
The Ball Motor
It’s a wonderful bit of creativity. I can see some potential sealing issues. Lubrication could be a bit tough (especially for the little ‘swash balls’ that follow a serpentine grove and move the ‘piston’ wedges back and forth). There is also a fairly large quenching surface area on the ‘pistons’ that could provide cold areas with the potential for lowered combustion and higher smog (probably ‘fixable’ with appropriate fuel injection that keeps fuel off the surfaces). OK, so I’d like to see one running and find out what ‘issues’ it might have. (The Wankel is a great engine, that had sealing problems, smog problems, and fuel efficiency problems from just those kinds of seals and surfaces issues… but makes a load of power in a low weight, so survives in some niche uses that need that feature).
What does it look like?
The animation starts with the inside shaft parts and takes you through the whole process adding one layer of engine at a time. Nicely done.
FWIW, an engine that I’ve always liked for the minimal ‘issues’ with things like valves, surface quenching, etc. is the Deltic engine. This was used in some boats and locomotives. First off, the pistons are opposed, so there are no ‘heads’ or valves. Just ports uncovered at the end of the stroke. Second, it’s a two stroke, so lots of power per pound. Third, it has a huge load of pistons per linear foot. Why? Because 3 cylinders are arranged in a “Delta” with a crankshaft at each apex. Pistons from each are opposed in each cylinder, so 6 pistons per unit length. All geared together at a rather large and complicated flywheel type affair. But still, no heads? No valves? 6 pistons per unit of crankshaft length? A ‘6 cylinder’ crankshaft length would give 36 total pistons each giving a power stroke on each rotation. Like having a 72 piston 4 stroke engine. Yeah, impressive…
From the Wiki:
Development began in 1947 and the first Deltic unit was produced in 1950. By January 1952 six engines were available, enough for full development and endurance trials. S212, a captured ex-German E-Boat powered by three Mercedes-Benz diesel engines, was selected for these trials, since its power units were of approximately equal power to the new 18-cylinder Deltic engines. Two of the three Mercedes-Benz engines were replaced with Napier Deltics, the compactness of the Deltic being graphically illustrated: they were half the size of the original engines. The Deltic weighed one fifth of its contemporaries of equivalent power.
Proving successful, Deltic diesel engines became a common powerplant in small and fast naval craft. The Royal Navy used them first in the Dark class fast attack craft. Subsequently they were used in a number of other smaller attack craft. The low magnetic signature lent itself to use in mine countermeasures vessels and the Deltic was selected to power the Ton class minesweeper. The Deltic engine is still in service in the Hunt class. These versions are de-rated to reduce engine stress.
Deltic diesels served in MTBs and PT Boats built for other navies. Particularly notable was the Norwegian Tjeld or Nasty class, which was also sold to Germany, Greece, and the United States Navy. Nasty class boats served in the Vietnam War, largely for covert operations.
Smaller nine-cylinder Deltic 9 engines were used as marine engines, notably by minesweepers. The Ton class vessels were powered by a pair of Deltic 18s and used an additional Deltic 9 for power generation for their magnetic influence sweep. The Hunt class used three Deltic 9s, two for propulsion and again one for power generation, but this time with a hydraulic pump integrated as well to power bow-thrusters for slow-speed manœuvring.
Just gotta love it. It’s a bit odd as one of the crankshafts has to run backwards relative to the others to get things to work out… I’d love to see a lightweight version made with high strength steels and aluminum (instead of iron castings) used in an airplane… You could run JP-4 instead of avgas and have a load of power too.
Here’s a schematic of how it looks in motion. (The wiki asserts the lower left side ports are reversed, that with rotational symmetry the exhaust and intake ought to be rotationally symmetric, not r/l symmetric with the lower right. So just imagine the purple and green swapped on that side.)
There is still room for development, especially in the area of a more fuel efficient alternative to the gas turbine. That path was explored some, but abandoned in the face of higher interest in turbines back when fuel cost was not much of an issue. Also from the wiki:
The E.185 or Compound Deltic turbo-compound variant was planned and a single prototype was built in 1956 and tested in 1957. This capitalised on Napier’s experience with both the Nomad and their increasing involvement with gas turbines. It used the Deltic as the gas generator inside a gas turbine, with both a twelve-stage axial compressor and a three stage gas turbine. Unlike the Nomad, this turbine was not mechanically coupled to the crankshaft but merely drove the compressor. It was hoped to produce 6,000 horsepower, with fuel economy and power-to-weight ratio “second to none”. Predictions by the engineers closely connected with it were that connecting rod failure would be the limit on this power, failing at around 5,300 bhp. On test it actually produced 5,600 bhp, before throwing a connecting rod through the crankcase just as predicted. Naval interest had waned by 1958 in favour of the pure gas turbine, despite its heavier fuel consumption, and no further development was carried out.
So I’m thinking that a ‘turbocharger’ like on the Mercedes Diesels applied to a bank of a small Deltic would give outrageous performance. It is, in essence, a coupled gas turbine / compressor. Put a small electrically powered or shaft driven blower on the intake for starting and ‘look out’… The biggest issue I see is finding a way to make one small enough to keep the power DOWN to the level of a 4 or 6 cylinder Lycoming ;-)
Ah, well. As it would take a fairly large company interested in a fairly small market to make one of those, it’s not likely to happen. Still, a fellow can dream … I suppose if you made it just one bank long, only 6 pistons, you could mount it on old radial engine mount points too ;-)
Now if I can just find a sugar daddy with a few $Million to spend on an aviation idea … An extraordinarily efficient, very smooth, high powered engine with great power to weight ratio and runs on Jet-A. Gotta be someone who would like it. Apply modern materials to the design and it ought to be a killer in the air. Rotating mass is a bit of an issue, but one third rotates opposite the rest. Gear the prop and flywheel to rotate in that counter direction and you could likely get low gyro impacts as well… Just saying…
(For those not familiar with the issue: Major oil companies would like to stop making aviation gasoline all together. There is just not much volume there and it’s a market of high regulatory and liability issues. They would like to just make jet fuel; and a lot of Jet-A / JP-4 / etc. is sold all over the world. There is a desire to make a Jet-A capable drop in replacement engine for private aircraft. A desire that has not quite managed to succeed in the USA. With high costs, mostly from regulations, and low potential sales, also from regulation killing off much of private aviation, it’s not a very attractive market. BTW, I’m one of those discouraged from flying by the regulatory burden, so I’m speaking from personal experience on that. Lots of ground school. Some flight time. Not nearly enough money. Where is the ‘Piper Cub’ or Taylorcraft of today? Killed by regulatory compliance costs for plane, pilot, and airports. The 4 cylinder Lycoming, for example, runs over $32,000 base price engine only. Why? It’s not the cost of making a 4 cylinder engine… The ‘ultralight’ movement is trying to fix that, but it’s just not a practical size for anything but ‘toy’ usage… by design. So I don’t expect to see any breakthrough soon. Most attempts are ‘mom and pop’ sized and fizzle on funding and /or compliance and acceptance testing.)