R-4360 Ruggedness

[Zipper730]

The R-4360 was a massive four-row radial engine which was air-cooled. The air-cooled nature made it quite popular over engines such as the liquid cooled V-3420.

Regardless, I remember reading a number of things that indicated that it seemed to be prone to fires, and might have lacked the ruggedness most radials have.

• The R-4360 used a geared fan to blow air through the engine to ensure cooling demands were met, which indicate that it was operating closer to the red-line and needed more effort to keep it working right.
• The oil-cooler was integrated into the cowling, which may very well have made the engine, to a limited extent oil cooled: This seems to make damage to the oil-system more likely than before.
• The B-36 seemed to have a high incidence of fires

Admittedly, there are some things that indicate otherwise

• The testing of the XF8B-1 indicated the engine was probably overcooled with the exhaust stacks being (at least partially) used to pump the duct.
• The R-4360's power output was increased over time, which would probably involve running it hotter and that, in turn, would increase the odds of fires breaking out
• The service life of the R-4360 was eventually increased to a couple thousand hours
• The B-36 had an installation that was probably far from optimal: The propeller behind the engine would mean little air is being blown in at low speed.

This still of course, doesn't really address the oil-cooler set-up...

 

[PWR4360-59B]

So your talking about just B-36 installations? Because what you are saying has nothing in common with other R-4360 installations.
A fan for cooling? Just B-36 installations. Since that was a buried in the wing pusher application there was needed a way to get some air in there to cool.
The most used R-4360 installation was in the C-97 / KC-97 aircraft, and that is where the service or TBO life of the engine was increased as new things were tried to increase its life span. The whole B-36 was sort of a joke, and should not be used to judge the R-4360 engines, the installation to use is the C-97's or even some of the race plane installations. You can't blame the engine for a bad plane design. C-97 / KC-97's were used for forest fire fighting after retirement from National guard units, and if all the good old recip planes weren't grounded years ago from fire service there would probably still be some used in that capacity. At least there is one C-97 that is flying now.
I don't remember any stories of C97 engine fires like you mention, and with any radial engine installation I feel the biggest cause of fires is bad mechanics, because there has to be something that causes them. I would sure think it is a leak of some sort that is the main cause or an electrical short, if the electrical system is properly protected a short should not cause a fire, any engine doesn't just catch on fire for no reason.
And yes a major engine failure with hot and broken parts can cause fires.
The engine with the reputation for fire related problems is the first R-3350's used on the B-29 caused by the forward facing front cylinders exhaust ports and the associated collector ring that they connect to, that was an engineering blooper, putting a furnace in front of those cylinders, actually the whole power section bathed in heat, just the opposite thing needed to help cool the thing. I guess alot of planes where lost over that engineering blunder.

 

[Zipper730]

So your talking about just B-36 installations?

I was talking about all R-4360's in general...

Because what you are saying has nothing in common with other R-4360 installations.

I didn't know that...

 

[PWR4360-59B]

I was talking about all R-4360's in general...
I didn't know that...

Almost everything you said in your first post was about R-4360 installations. Oil cooler, again all about the installation. Not much was related to the basic engine. To better compare just the engine or engines it would be better to be concerned about how they perform on a dynamometer or test stand.
There you don't have the variables of aircraft installations, the oil cooler is not a concern then, really the oil cooler install point has zero to do with the engine itself, that is an airframe designers problem, if it does not perform still again that is not the engine designers problem. All I see in that post is how this or that is installed. And basically nothing about the engine.

 

[Shortround6]

The R-4360 was a complicated piece of machinery and needed a well engineered installation and careful maintenance.
However it powered a number of aircraft in numbers and 18,697 were built. The last in 1955.
Not including odd-balls and rarities you had
56 Boeing 377 Stratocruisers
370 Boeing B-50 bombers
74 Boeing C-97 Stratofreighters.
811 Boeing KC-97 Stratofreighter/tankers.
448 Douglas C-124 Globemaster IIs ( and 14 C-74 Globemaster).
1,183 Fairchild Flying Boxcars.

and the 384 B-36s.

 

[Jim Daigneau]

I think the above discussion was also true of the R3350. Both engines were the ultimate radial engines, pushing the technology and materials to the max. Initially, fire and failure was just part of the process. But, as noted, once the crews learned how to operate them, they would last a long time on wing and perform well.
The bigger problem was fuel. The 4360 really needed military grade/115/145 octane to run at peak efficiency. The 3350 ran okay on 108/130, but of course the best on 115. Both could be run on common 100 oct, but there were significant penalties for takeoff and METO power settings. Thus the success of the C/KC-97 and the very limited run of the civilian B377.
The 4360 also was a fuel guzzler and even super- leaning yielded almost jet-like fuel flows. NWA folks used to joke that the "break even load factor on their Strats was 110%".
Just my 2 cents, as I don't often post. But the later radial engines have always fascinated me and embody great ingenuity and manufacturing expertise.

 

[PWR4360-59B]

I think the above discussion was also true of the R3350. Both engines were the ultimate radial engines, pushing the technology and materials to the max. Initially, fire and failure was just part of the process. But, as noted, once the crews learned how to operate them, they would last a long time on wing and perform well.
The bigger problem was fuel. The 4360 really needed military grade/115/145 octane to run at peak efficiency. The 3350 ran okay on 108/130, but of course the best on 115. Both could be run on common 100 oct, but there were significant penalties for takeoff and METO power settings. Thus the success of the C/KC-97 and the very limited run of the civilian B377.
The 4360 also was a fuel guzzler and even super- leaning yielded almost jet-like fuel flows. NWA folks used to joke that the "break even load factor on their Strats was 110%".
Just my 2 cents, as I don't often post. But the later radial engines have always fascinated me and embody great ingenuity and manufacturing expertise.

Jet like fuel flows? 150 Gal / H ? vs a gallon a second or more.
C-97 cruise hp was under 2k hp if memory serves.

 

[Jim Daigneau]

Total fuel flow, not per engine. Leaned out to normal cruise I think would yield about 3000-3500 ppl total. But, you have to figure that producing a TAS in the mid 300 kts. And, of course only carrying 100 or so people. So, where I was going with the line of thought: it was a goodly amount of gas and a fairly high CASM.
On the other hand, don't get me wrong: it was an awesome airplane and the passengers were reported to love the luxury and space. The mechanics and bean counters not so much.

 

[PWR4360-59B]

My jet fuel flow was a per engine number, especially back in the day they where super inefficient, and why Eddy Rickenbacker wanted nothing to do with them. Recip overhauls where dirt cheap then, pay was low. So a total fuel flow for a 4 engine, R-4360 plane would be about, 600 gallons per hour, and a jet 14,400 gallons per hour for a 4 engine plane . So makes a nice R-4360 look like a huge fuel saver.

 

[special ed]

As a teenager in the 50s I could always tell when 4360s were overhead, usually in C-124 or B-36

 

[Shortround6]

My jet fuel flow was a per engine number, especially back in the day they where super inefficient, and why Eddy Rickenbacker wanted nothing to do with them. Recip overhauls where dirt cheap then, pay was low. So a total fuel flow for a 4 engine, R-4360 plane would be about, 600 gallons per hour, and a jet 14,400 gallons per hour for a 4 engine plane . So makes a nice R-4360 look like a huge fuel saver.

It would have been a huge fuel saver if this was anywhere near true, But since it isn't.............

Fuel capacity for a Boeing 707-120,-220 was 13,478 gallons. Less than 1 hour endurance??
Fuel capacity for a Boeing 707-120B was 17,334 gallons. 1.2 hours endurance???
Fuel capacity for a Boeing 707-320, -320B, -320C,-420 was 23,855 gallons. less than 1.66 hours of endurance?????

These must have been mighty fast planes as the -320 had a range with max fuel, allowing for climb and decent but no reserve of 6620 miles.
And it could do it in under two hours????? My, My a SR-71 has got nothing on a 707

A 707-120 could cruise at 549mph (economical not max) and it's 13,478 gallons was good for 4650 miles making allowances for climb and decent. so it looks like the 707 was burning an average of 1591 gallons an hour.

But wait,,,, there's more.
The 707 burned 1591 gallons to go 549 miles (2.9 gallons per mile), the Boeing 377 burned between 497 gal and 600 gallons to go 315-340 miles (1.58 gallons per mile) low number?


But wait,,,, there's more.

The 377 carried 81 passengers in standard configuration (up to 117 in hi-density late in career) while the 707-120 could carry 141 in a standard configuration (36 first class) or 181 in hi-density (6 abreast through the whole plane) so using the hi-density numbers the 377 used 0.0135 gallons to carry one passenger one mile while the 707-120 with those thirsty jet engines used 0.016 gallons to carry one passenger one mile. A whopping 19% more and not many times.

But wait,,,, there's more.

the Boeing 377 was burning 108/135 fuel (hardly cheap stuff) and used water injection for take-off when needed.

The 707-120 used JP-4 (basically a 50/50 mixture of kerosene and gasoline) for a huge difference in the price per gallon.

 

[PWR4360-59B]

All the old planes where under designed for speed and capacity. I wouldn't put it past the airlines and manufactures begging for jet fuel subsidies, and that being the main thing that ushered in the jet powered planes. Using your numbers the 4360 still using less than half the fuel.
It is very difficult to find accurate fuel burn on jets, its like a huge secret.
This mentions 40 gallons per minute per engine on a 707 so go pooooo on them as well.
What is the fuel consumption of a Boeing 777 as compared to a Boeing 707?
The comments below are great and how the one fellow talks about a prop engine on wing, others say what you do and others say what I kind of did.

 

[Shortround6]

Fuel capacities I used and ranges are from several editions of Jane's.
Some of those people don't seem to know the difference between take-off and cruising.

And it is not the difference in fuel per hour that counts but fuel per mile flown. And then the fuel per passenger mile.

 

[PWR4360-59B]

Maybe not so much now but years ago I heard stories of way under passengerized planes, ones that only had a fraction of capacity, kinda ruins the per passenger deal. And for the worlds fuel / oil supply its a how much fuel is guzzled deal and nothing else. No matter how you state it turbine engines are massive fuel guzzlers.

 

[special ed]

I know this has turned into fuel consumption, but thought I would add to post #5 Martin P4M mercator and the naval boxcar R4Q-1. Just for the levity a story from 1960. On leave, a buddy and I Hitched a ride on an empty C-97 from Tuscon to Barksdale. The pilot looked the same age as us (he was 2nd Lt), never saw the co-pilot, and crew chief looked double our age. I was 19 at the time. Pilot gave us this emergency briefing: The fire bottles for the engines are out and could not be serviced here and the warning alarm is out.so if you see me or the others running to the back, get in line and keep up.

 

[PWR4360-59B]

And likely the same inexperienced aged mechanics doing the work them as well. But one plus in those days those aged persons had a bit more on the ball. And so how does that story end?
Yeah sorry I don't like off topic either.

 

[special ed]

A nice uneventful flight and touchdown. The flight from Shrieveport to New Orleans on Trans Texas Airlines (TTA) was notable as the stewdardess was so tall she couldn't walk with her head up in the DC-3. Well, maybe an exaggeration.

 

[PWR4360-59B]

The longevity and ruggedness of any of the large piston engines lays in the hands of the operators, and that includes the maintenance people as well as the flight crew. If they operate them outside the correct parameters then the reliability will suffer. Yes some of the engines had some issues mechanically that had to be watched, most of those were worked out as usage time progressed and fixes where done to eliminate them.

 

[fliger747]

14000 gal/hr sounds a bit high, we would fuel up a 747-400 with about 35,000 gal in Hong Kong for a flight to Anchorage. In a 737-400 14000 lbs would be a fuel burn from Anchorage to Seattle, a 727 about 24,000 lbs.

Once flying over China, pretty high and a little time to waste between position reports I figured we were doing about 3 gal/mile (USG-Nautical miles). Not bad for a rather large plane doing over 500 knots. But then look at the fuel flow on takeoff when we were putting out over 250,000 lbs of thrust... Jets need to be high for economy. I won't go into the rather complex factors that go to optimization of cruise. Generally we counted on an average of 10,000 kg/hour with a load. just a rule of thumb and only to check for reasonableness.

The turbo compound piston pounders were engineering marvels and maybe the carrying of the technology about one step too far.

Don't forget about the rather impressive F2G!

 

[Zipper730]

Misinterpreted post earlier