Talk:Junkers Jumo 222/Archive 1

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Quote: "The engine looked like a radial due to the arrangement, but the internal workings were more like a V engine" From Janes Fighting Aircraft of WW2: "Type: Tweny-four cylinder multi-bank radial" "Connecting Rods.-Split master rods and five articulated rods in each of the four banks of cylinders"

From wikipedia: "In a radial engine, the pistons are connected to the crankshaft with a master-and-articulating-rod assembly."

In summary, it is unlikely the Jumo 222 could have been anything other than a radial engine, the difficulty of connecting 6 planar cylinders around a single crank using any other method than the radial type master/articulated rods would have been immense — Preceding unsigned comment added by 121.74.96.180 (talk) 21:29, 16 September 2011 (UTC)

"multiple bank in-line"?

Why is this a "multiple bank in-line" engine? A "V" type engine has multiple banks (two) and is not an "inline". Shouldn't this be simply a "multiple bank" engine? ReTeam (talk) 16:10, 15 December 2015 (UTC)

It's an inline radial, which is a distinct, albeit obscure, group.

In aircraft practice, single bank engines, V engines, and W engines are all considered as inlines (as distinct from radials). Multiple row radials have staggered cylinders with separate cylinder barrels so aren't inline. A few, the inline radials, are both inline and radial. See the Armstrong Siddeley Deerhound, the Zvezda M503 and a few others.

Most high-powered inline aircraft engines are liquid cooled, as air-cooled engines mostly need the separate front-facing barrels of the radial in order to get enough airflow. There are a few air-cooled Vees and inlines, which duct air down one side and sideways across single cylinders to cool them. When this was tried for the even rarer air-cooled inline radials (see the Armstrong-Siddeleys) it turned out to be too difficult to achieve adequate airflow. Andy Dingley (talk) 16:45, 15 December 2015 (UTC)

Wow, what a fast reply. Thank you. I am not going to edit, I just thought it was a good question for someone who was. I knew the Chrysler thing in the M4AA4 was called "multi-bank" without the "inline", just like V and opposed.

I get the thermal problems, I think you can keep the temperature more stable with liquid, too. Aircraft just have so much air coming from the front, parallel to the crank.

PS: I never understood horizontal crank radials in tanks, once you have the cylinders below horizontal you have oil problems. I think all the air coming from the front in aircraft make it worthwhile.

Thank you for your time. ReTeam (talk) 18:34, 15 December 2015 (UTC)

Multi-bank is different again. They're a number of cylinder blocks and crankshafts put together, then the crankshafts geared. This was done for the tank engine as a simple way of using a truck engine factory (and its smaller single-plane machine tools) to make engines big enough for tanks.

There have been a few aircraft engines like this too (although mostly designed from the outset): 1930s H engines, like the Napier Dagger or Fairey Monarch, where cylinders were kept small for efficiency and limiting piston surface speed, but still needed to be a large capacity engine. Also a handful of X engines, like the unsuccessful Rolls-Royce Vulture, where two vees (Kestrels) were coupled with a single crankshaft. Sharing the crankshaft, and the limitations on the bearings, were what did for the Vulture.

The tank radial engines were used because they were there. Aircraft had already developed high-powered engines, which tanks then needed. There was no other way to do this: some tanks used pairs of truck or bus engines, which were bulky and needed extra transmission gearing. Developing a new engine specifically for tanks would take too long and if done by the non-aircraft truck engine makers still wouldn't reach the performance needed. Simplified aircraft engines (no superchargers or altitude equipment for the carburettors) were the expedient option. With the US light tanks, the smaller radials fitted the available space. There were even radial diesels to be had, made in diesel aircraft engine factories that would otherwise be unwanted. As tanks grew heavier though, the radial approach became increasingly impractical and height was only one aspect. Getting enough cooling airflow was another problem. For the M4 Sherman though, the space already provided for the radial did mean that (unlike British tanks) it was quite easy to find other engines that could fit the space available. Andy Dingley (talk) 20:23, 15 December 2015 (UTC)

Five cranks, of course, I should have realized that. I knew it was make-shift, I looked it up. 30 cylinder 1,253 CID flathead to make 425 hp. Desperate measures for desperate times.

Napier seems to have specialized in weird designs. Keeps the engineers busy, I guess.

Yes, the Guibersons were unwanted. Ironically, the Germans might have liked them. ReTeam (talk) 02:56, 16 December 2015 (UTC)

Napier weren't so limited by convention as Rolls-Royce were. They had early-on licence-built German opposed piston diesels and although I don't believe the "Everything Napier ever did was German" viewpoint that keeps popping up re the Deltic, the pre-war diesels did make them recognise that other layouts were credible. Personally I don't think radial diesels make much sense: radials are a solution to petrol problems. Diesels all ought to be opposed piston ported, petrol aircraft engines should be sleeve-valve radials.

There's also the issue of range. "Long range" to Germany meant rather less than the Pacific-facing US. The German diesel seaplanes were excellent aircraft for the maritime patrol needs of mainland Europe. Atlantic convoy protection though needed much longer range, thus heavier aircraft and more engine power. It took Napier so long to develop such diesels, the Nomad and the aero-Deltic, that they ran into UK procurement policy problems and missed the market altogether. UK patrol aircraft were seen as needing a high dash speed to get them out to the distant patrol areas without wasting endurance and turboprops could provide this more readily (which in the end of course never happened). NATO maritime recon procurement split, with most using the Breguet Atlantic, a sensible twin turboprop, and the long-ranged Brits needing to go their own way. Andy Dingley (talk) 10:39, 16 December 2015 (UTC)

Clearly different machines for different applications, but I am missing something(s).

Radials relate to air-cooling, how is gas or diesel different?

Why do you try to sell O-P? Pretty complex way to try to make ports work, and in the end you still have a two-stroke diesel. F-Ms for marine service are the only actually successful design, lasting forever, but in a marine engine you run about the same speed indefinitely, right?. No valve train to maintain, but valves are not all that tough. Every 4-stroke, and GM 2-stroke diesels, have been using them forever.

If you want mileage, why would you use any type of 2-stroke diesel?

Sleeve valves?

Are you out in Extreme Theoryville? Nobody uses O-Ps or sleeve valves because they aren’t practical. A lot of engineers have been thrown at these ideas, with only one success (F-M). Unless you consider the Deltic a success (they were a maintenance nightmare, right?). And couldn’t a radial with four banks of three cylinders do the same as a Deltic, and easier?

Four strokes, some poppets, and one piston per bore works. ReTeam (talk) 05:53, 17 December 2015 (UTC)

Making big petrol aircraft engines is a problem of how to cool them. Making big diesels is a problem of arranging scavenging airflow. Radials help with cooling.

Uniflow diesels are a great way to make diesels. Piston porting them with opposed pistons is a good way to make uniflows. Single piston uniflows (piston inlets, poppet valve exhausts) aren't bad either. They're also a simple design to manufacture - costs a geartrain and twice as much on crankshafts, but loses valves and valve seats, camshafts, cam drives, and becomes much less critical for manifolding. A big advantage is not needing to service valvegear. Service intervals on these engines ("one day downtime" scale servicing) are much longer. Make a Deltic and you don't even need two cranks.

There's a world of engines outside the US. Junkers were doing these from around 1900. Doxford built everlasting ship diesels that could outlive a hull. Even within the US, the GM 6-71 series was a very successful single piston uniflow two stroke diesel for decades. These engines do work better at the medium large scale and at constant loads, so they're more suited for generators, small ships and railway use. The Soviets in particular ran their whole railway network on inline opposed piston diesels, and pretty successfully too. In the UK the Commer TS3 (3 cylinder horizontal opposed piston) was a splendid engine for large trucks (medium trucks these days) that appeared early on and was only removed by corporate mergers. Its biggest manufacturing cost was the lobes for the Roots blower and those are far, far easier in a CNC-equipped world.

The Deltic was a superb engine. It had four troubles over its life: liner cracking and piston cooling were development issues, soon solved. The big reliability problem in the '70s was when BREL took engine rebuilding in-house, rather than sending them back to Napiers, as before and as for the naval engines. They didn't work to the standards needed for a diesel of this sophistication, and the engines suffered. Exhaust fires from oil in the collector drums remain a problem to this day (one was lost in preservation, damaged more by enthusiastic firemen with big hoses than by the fire)

Supercharging is also so beneficial to diesels that it's pretty much universal (for today's economics, and fuel costs vs. blower manufacture). So the big advantage of the four stroke, not needing a separate scavenge blower, disappears.

For powerful petrol engines, single sleeve valves have been an excellent solution since Bristol solved their manufacturing problems in the 1930s. The Bristol Centaurus is probably the best piston aircraft engine ever built, including the corncobs. Cost isn't any better (Max Bentele thought there were too many gears), but maintenance savings certainly are. Again, these were killed off by corporate mergers in the '60s - in R-R's view, anything from its absorbed companies was either to be claimed as its own (the "Rolls-Royce" Olympus or Pegasus) or else they pretended it never existed (any radial engine).

Modern fashion for petrol engines is turbocharging, but this is its own can of worms. OK for "money no object" sportscars, especially now that electronics are cheap, but the problems are vast. Note how few real supercars are turbocharged, when a large capacity V12 is an option. VW despite, I think we're seeing a gradual decline in petrol domestic cars in favour of turbo diesels (4 stroke with poppet valves, as they're under such varying loads) - a much simpler prospect. Andy Dingley (talk) 14:55, 18 December 2015 (UTC)

I am admittedly using US examples, I know them.

In both gasoline and diesel radial engines, if air-cooled, the heat problems are similar. Scavenging doesn’t relate.

Your second paragraph is confusing.

“Uniflow” two-strokes need forced induction. With forced induction the “scavenging” problem is only the amount of restriction in the passages, like running with/without air cleaners and mufflers. With a carburetor you have to worry about fuel separation, otherwise two and four stroke restrictions are similar. In fact, the four-stroke would have an advantage, not having to route the air between the cylinders.

Turbochargers are no longer cost-prohibitive. You can no longer throw all that exhaust heat energy away. Virtually all US heavy truck and rail locomotive engines are turbocharged, I suspect that is worldwide. Turbochargers’ weaknesses in automobiles is not money. Turbos need to be properly warmed up to last, and they are always behind demand on speed changes. Turbo lag.

Opposed pistons could be used as four-strokes too. The basic form is the failure, not being a two-stroke. They need two cranks, or one with all kinds of levers. The Deltic actually uses three crankshafts, and one counter-rotates, with those extra problems.

There were 32 Deltics locomotives built in 1959-1962, they were out of service in 25 years? Is that a success? After 1962 Deltics were only built for the military, correct?

I didn’t know much about marine diesels, so I did some homework:

Very large, low speed engines are two stroke [1] [2][3][4] compression ignition with poppet exhaust valves and one cylinder per bore driving a single crankshaft. Except for the Doxford, which hasn’t been produced in twenty-five years?

All engine blocks last as long as the vehicle they are in, they design them that way. Have you ever replaced the block in any car you have owned?

Medium speed engines are usually four-strokes[5][6][7][8] four-strokes, except for EMC/EMDs and the F-Ms (probably the only really successful O-P engine ever built). (I included the O-P link to be fair, it has the same theories and names that you have, including the only successful O-P, the F-M).

Jumo O-Ps were successful outside the military? Really?

Saying something was “only removed by corporate mergers” and “were killed off by corporate mergers in the '60s” is misleading at best. Corporate mergers do cause rationalization. For money. If the Commer was a financially successful design all R-R engines would be Commers with R-R nameplates. Money counts, not emotion. Now R-R only builds O-Ps for the military, correct?

The Bristol Centaurus “is probably the best piston aircraft engine ever built”? 35,00 were built, against 125,000 P&W Double Wasps. Both had development problems.

If the Centaurus was so good, the US would have license-built a ton, like the 55,523 Merlins that Packard built. A third of all Merlins were built by the US, not one Centaurus.

Even if the Centaurus was “probably the best piston aircraft engine ever built”, what other sleeve valve engine was ever really successful?

Just because something is successful in the military doesn’t mean it is successful in the real world. Large militarys (UK, USA, USSR) set their special (often extreme) needs, then make companies build to their wishes. They have the money to develop the technology, but what they do with it doesn’t need to be commercially useful.

I do not understand. There are a zillion engines out there, you have one example of a commercially successful O-P. There are a zillion poppet valves out there, you have one example of a successful sleeve valve. Why are you beating these two dead horses? Maybe we should agree to disagree? ReTeam (talk) 00:49, 20 December 2015 (UTC)

Three tags

• This is tagged "This article may be unbalanced towards certain viewpoints".

What view point? It is not good to "tag and run", please add note here.

• References, tag is clear.

• Tag: "This article possibly contains original research." Is this due to lack of references, or is there something more?

Telecine Guy (talk) 00:15, 30 January 2017 (UTC)

All the tags but the References one were added by a new user in May 2016 as the fifth of his five edits, all made that week. I agree there's no obvious issues, so I've reverted his tags. Hopefully the tags won't come back without an explanation here. - BilCat (talk) 00:25, 30 January 2017 (UTC)

Radials

The distinction between a radial and a multibank inline has mostly to do with the firing order. Being liquid cooled or having crossflow heads makes no difference. Nothing prevents a liquid cooled radial from being built, and air cooled inlines are not exactly rare. A crossflow head can be used on any layout of engine. This text seems to imply that 'well, its sort of a radial, but it's liquid cooled and has crossflow heads, which are more common on inlines, so we call it an inline'. That's ridiculous. It's an inline because of the firing order of the cylinders. If it was a radial, you couldn't easily use SIX cylinders per row, it would have to an odd number (unless it was a 2 stroke).

64.222.107.65 (talk) 20:15, 7 September 2020 (UTC)