Largest Piston Airliner?

[stepwilk]

"Maintenance costs on something like a 24 cylinder Wright Turbo Compound..."

The R-3350, which I've flown, had 18 cylinders. There would be no possible way to configure a multi-row (or for that matter single-row) radial with 24 cylinders.

[Groundloop]

I knew it had a helluva lot of cylinders but didn't bother checking the fine details.

The point I was trying to make is that they could not be compared with a 4-cylinder Lycoming.

Sorry

[one11]

Greatest number of prop passengers

This one is causing to cause all sorts of problems for definitions.

On 21st October 1929, the Dornier Do X 12-engined flying boat carried the greatest number to fly in one aircraft up to that time. 10 crew, 150 passengers and 9 stowaways. So, its either the winner or a good runner up to the Armagnac.........but it was a one-off not a scheduled service.

Likewise, if you include airships, the Graf Zeppelin (4 Diesels) carried 150 +45 crew on short flights but only 50 intercontinental. It would certainly win on length or volume criteria.

[HuntandFish]

Off message , but did the Dornier DOX have the most piston engines with 12 . Only 100 or so passengers though.

[Tyres O'Flaherty]

Agaricus bisporus

Re Connie ''jollies'', not sure of the present status of it, but I think that's the plan for the Lufthansa Constellation.

Damn I need to get saving

[StickFlyer]

Glad to have asked this question! A lot of interesting aircraft I never knew
existed and great pictures, I bet they sounded great too

I looked for Soviet behemoths but it seems they quickly pressed on with turboprops after the war eg the IL-18's and took a while to consider really large passenger planes. The DC3-like IL-14 was the largest I found

Re: the piston engine. Apologies yes I was thinking of 4 cylinder Lycomings in today's small passenger planes being cheaper than perhaps a turbo prop in the same plane, not the large radial engines that powered those beasts! I should have made it clearer I was thinking about very small passenger piston aircraft

One piston still flying today is the AN-2 which I think has 10 seats and theres a large Cessna or two. And some bush planes
But I'm not sure which of them carries the most pax... ?

[evansb]

The De Havilland Canada DHC-3 Otter is still in daily operation, and carries 10 or 11 passengers.

[WHBM]

Originally Posted by Agaricus bisporus

With the reliability problems of the Connies, for instance, (engine shutdowns a weekly event)

It wasn't the Connie itself that was unreliable, but the Wright Turbo-Compound engine it used. This was never got right. Douglas made the unwise step of moving on from the DC-6 (Pratt & Whitney engines) to the DC-7 (Wright Turbo Compounds) and got all the problems of the engine too. The jets came along shortly afterwards, the older DC-6s carried on in secondary tasks all through the 1960s and beyond but the DC-7s mostly went to the breakers straight away. Some hadn't had 5 years service.

But even this was nothing compared to the initial usage of the Wright engine in WW2. The B29 was renowned for engine failures in the Pacific, it seems to have accounted for almost as many losses as enemy action. It is quite unbelievable that the atomc bomb was put onto such an unreliable aircraft, although I did read once that the Enola Gay engines had been hand-built by engineers rather than taken from the normal assembly line. Another account described a scene at Guam in 1945 where USAF maintenance had accumulated a huge mountain of unserviceable Wright engines off B29s, hundreds of them, which was about 30 feet high, they must have been using a crane to pile them up like that. I wonder what became of them (cruel cynics would say they were shipped back to the US and sold to Lockheed for the Connie ).

[con-pilot]

But even this was nothing compared to the initial usage of the Wright engine in WW2. The B29 was renowned for engine failures in the Pacific, it seems to have accounted for almost as many losses as enemy action.

Quite correct, my father flew B-29s and he told me that at max combat takeoff weight the loss of just one engine on takeoff would result in a crash, nearly all of which were fatal to all crew members. I'm trying to recall exactly how long after takeoff it was until the B-29 could be in a position to return for a safe landing after the loss of a engine. I think, and am willing to be corrected, that it was around three minutes and that required dumping the bomb load. He said basically that all takeoffs were 'ground effect' takeoffs before they knew what 'ground effect' was.

My father considered the B-29 horribly under powered. The B-50 was much better.

[WHBM]

Bregeut Deux Ponts

Another type I remember, known to us schoolkids, alas, as the "Duck's Pants". There was a deep night Air France freighter which in the mid-1960s made a climbing turn out of Heathrow over a relative's house in Chertsey at about 02.00, maybe at 1,000 feet if they were lucky, and was renowned for waking up the whole town.

But more remembered was one of the Air France pax/freighter combi conversions which did the afternoon flight a few days a week from Paris to Bristol and back, up to about 1968. I was once allowed to accompany next door's au pair (who, as I was an immature 15 year old, I quite fancied), returning to Paris, to Bristol Lulsgate to "show the way", we took a local bus which put us off at Lulsgate Bottom, and walked up the remaining half mile to the airport, me manfully struggling with her suitcase, with the Deux Ponts silhouetted on the skyline against the evening winter sunset. It was the only one I ever actually saw (that Chertsey one was only heard). They seemed to have got about half a dozen pax that day, who would have been lost in such a large aircraft, goodness knows why it was used on the route.

[Agaricus bisporus]

Some alarming "facts" from Wikipedia. The article also says that the B29 had an impressive power to weight ratio which hardly seems in line with the Confederate Air Force's experience. Changing the top cylinders every two - three missions! Man, that was one problem aeroplane!

Thanks, I'll stick to turbines.

an engine that would overheat regularly at combat weights, particularly during climbs after takeoff. Unseated valves released fuel-air mixtures during engine combustion that acted as a blowtorch against the valve stems. When these burned through the engines disintegrated and caught fire. A fire that was not immediately contained in the forward part of the engine by fire extinguishers became impossible to put out. An accessory housing manufactured of magnesium alloy in the back of the engine would often catch fire and produce heat so intense it burned through the firewall to the main wing spar in no more than 90 seconds, resulting in catastrophic failure of the wing.
This problem would not be fully cured until the aircraft was re-engined with the more powerful Pratt & Whitney R-4360 "Wasp Major" in the B-29D/B-50 program, which arrived too late for World War II. Interim measures included cuffs placed on propeller blades to divert a greater flow of cooling air into the intakes, which had baffles installed to direct a stream of air onto the exhaust valves. Oil flow to the valves was also increased, asbestos baffles installed around rubber push rod fittings to prevent oil loss, thorough pre-flight inspections made to detect unseated valves, and frequent replacement of the uppermost five cylinders (every 25 hours of engine time) and the entire engines (every 75 hours).[3]
Pilots, including the present-day pilots of the Commemorative Air Force’s Fifi, the last-remaining flying B-29, describe flight after takeoff as being an urgent struggle for airspeed (generally, flight after takeoff should consist of striving for altitude). Radial engines need airflow to keep them cool, and failure to get up to speed as soon as possible could result in an engine failure and risk of fire.

[philbky]

Re the Deux Ponts, it featured in many a publication in the 1950s concerning London Airport, as it then was, due to the fact that Air France used it as a back up aircraft for their Paris schedules (back up both in terms of replacement aircraft and extra capacity).

I remember them in the 1950s when they seemed huge compared to everything else in front of Queens Buildings and later, in the 1960s, I'd regularly see one on the way to school as they flew an early morning freight flight into Manchester.

The last Air France one I saw was at Toussus le Noble, unfortunately in bits as it was scrapped in early 1979 and was still lying around at the time of the Paris show that year. I drove right up to it, parked next to the ex Senegal Govt Constellation, also awaiting scrapping and was able to climb aboard what was left of the cockpit.

Here's a photo taken the same month with the outer fin of the Connie showing at the rear. F-BASX - Air France Breguet 763 Deux Ponts Aircraft - Toussus-Le-Noble Photo @ Airplane-Pictures.net By the time I was there the Deux Ponts' the nose had been cut of and the cockpit section was lying at an angle on the ground.

Of course the official name was the Breguet Provence, the military version being the Sahara and Air France called them the Universel when used as freighters - and weren't those upward opening lower fuselage doors impressive?

I seem to recall 1950s publications talking of a large percentage of wood being used in the fuselage construction but don't remember seeing too much wood lying around at Toussus. Anyone like to comment?

[WHBM]

I see above the B-29 was finally re-engined with the P&W R-4360, same engine that went into the Boeing Stratocruiser. This had issues of it's own, among them a propensity of the props to shed blades in the cruise, especially mid-ocean (possibly an issue of how much power they had to handle).

The R-4360 was a 28-cylinder (7-cyl x 4 rows). On a 4-engined aircraft that's 224 sparking plugs, what chance all would be working 100% in the mag check ? It also suffered from having 4 rows of cylinders, the back row were just too shielded by those in front and would overheat. The Big Ends on the crankshaft must have been a fitter's delight as well !

[Warmtoast]

Breguet Deux-Ponts got a mention in the press when it visited London in June 1954 as this press cutting shows:

[Noyade]

I seem to recall 1950s publications talking of a large percentage of wood being used in the fuselage construction but don't remember seeing too much wood lying around at Toussus. Anyone like to comment?

There's a good article on the Breguet in Aeroplane Monthly (July 1992) by John Stroud and he describes it as an all-metal aircraft.
"The unpressurised fuselage, of duralumin with stressed metal skin..."

[philbky]

That would tie in with my recollection of the wreck and the photos I took at Toussus.

[StickFlyer]

Well since one flew over my house today and the sound had me scurrying out to see what it was - Largest piston airplane regularly carrying passengers today - the Trislander (17). Good old England

[parabellum]

I can remember that around 1950(ish) there were some fairly big flying boats at Hythe, near Southampton, new in those days, I think, not sure if they had four or six engines? Can't find anything on Google so maybe it never entered passenger service.

[HarmoniousDragmaster]

Could you be thinking of the Short Shetland? There was one civil prototype of this boat. It was bigger than a Sunderland (of which you would have also seen the civil version, the Solent, Sandringham etc) but smaller than the Princess, but had four piston engines.

[kitwe]

Parabellum.

The flying boats in question were SARO Princesses and they were still in existence in 1965. Three were built but I think only one (G-ALUN) was completed and flown. I don't think it ever entered service.