Would B-29s have been better with R-2800s?

[Brian Abraham]

Certainly R-2800s weren't routinely pulled through on P-47s and all the rest of the airplanes that carried them

Sloppy procedures if that is indeed the case. From 2800 notes - Up to 10 gallons of oil were trapped in the system following shutdown despite it being a dry sump. Some of this oil will inevitably find its way into the lower cylinders through leakage past the piston rings and oil trapped in the rocker boxes leaking through the valve stems. Being incompressible any excess oil in the lower cylinders has the potential to wreak havoc inside the engine. Bent connecting rods are not uncommon. As a guard against this kind of catastrophe the 2800 has a clutch on the starter, the aim of which is to prevent damage in the case of a hydraulic lock. The fierce acceleration induced into the engine upon engagement of the starter can cause heavy internal loading, and that is assuming nothing is amiss such as a hydraulic lock. Even with the protection of the clutch, serious damage can result if the engine is hydraulic locked.

[swordfish41]

The Treasure of the Humboldt Glacier

I was the director and producer of the documentary about the Kee Bird and Darryl. It exists in two versions one for NOVA in the US and one for Channel 4 in the UK which was broadcast with the above title. I think I know Funky Stick also. Brian Abraham is right about the need to turn the engines, and in the second trip when Darryl wanted to use the frozen lake as a runway the props were being turned every half hour it seemed to me, and i can definately confirm that it was possible to remove the plugs to drain the lower cylinders without removing the props. When the Kee Birds Squadron first started operating from Alaska there were several crashes after takeoff. It was standard procedure in the Pacific theatre to open the cowl flaps fully on take off to prevent the engines from overheating. This had the reverse effect in Alaska so after the first crashes they took off with cowl flaps closed. There are of course four of these engines still up at the crash site in Greenland with very low hours on them. I know at least one person who has been up there recently to take a look. The saga continues.
sf41

[Brian Abraham]

It was standard procedure in the Pacific theatre to open the cowl flaps fully on take off to prevent the engines from overheating.

Someone was smoking something when they told you that swordfish As you say overheating during prolonged ground operation was a problem. Take off was not permitted once the cylinder head temp had exceeded 220°C. The procedure was to set the cowl flaps at 15° upon entering the runway and reducing to 7.5° or less by the time the aircraft leaves the ground. This permits rapid increase of airspeed and should keep the cylinders below 260° (max for take off 260, climb 248, cruise 232). If 260 is exceeded cowl flaps may be opened to a maximum of 10°, larger openings provide little if any additional cooling. Power may be reduced on the offending engine but not until the aircraft has reached 170mph.

To illustrate what might happen with a take off with the cowl flaps open, a Boeing Stratocruiser (basically a passenger version of the B-29) ditched in Puget Sound following take off from Seattle because of such an error. The open cowls create a huge airbrake and the turbulence produced severe vibrations, loss of lift and lateral instability, to the point the Captain thought he might lose control and this prompted his ditching. These symptoms however did not show themselves until the wing flaps were retracted from the take off setting of 25° and passing through the 10° position. The crew thought they may have had a asymmetric flap condition. Subsequent tests showed that the effect of the open cowl flaps on aircraft performance was the same as if an engine had failed and the cowl flaps were in their normal closed position. The root cause of the accident was thought perhaps to be the engineer who was mainly experienced on the Constellation, in which the switches operated in the reverse order to the Stratocruiser.

[Feather #3]

In case it makes a difference, didn't the Strat have R-4360's?

G'day

[Brian Abraham]

Affirm, as did the re-engined B-29 which became the B-50. The B-29 contains a cautionary note regarding severe vibration with the cowl flaps open in flight. As an aside every degree of cowl flap above 10° opening increased fuel consumption by at least 15 gallons per hour. With four engines and flying 16 hour missions to Japan it took precise flying to get the most out of the aircraft. Reducing drag (intercooler doors and cowl flaps) is a prime concern through out the manuals because of its tremendous impact on performance. Cowl flaps open 6° reduced speed by 10mph and so expected cowl flap cooling requirement had a considerable effect on flight planning.

[swordfish41]

Whoops

Brian,
thanks for the clarification. I'm not an engineer obviously, so take your point about the cowl flap settings in the Pacific. However the information about the early crashes in Alaska, and the reason for them was given in a book about the history of the squadron. What I understood, (and what do I know) was that the temperatures were so low that the normal setting of the cowl flaps prevented the engines from delivering the necessary power. I think I still have the book, some where in storage. This may of course have been nonsense, there was a great deal about the official history of the Kee Bird that I found to be erroneous.
sf41

[Brian Abraham]

swordfish, I wonder if the following contains a germ around which your story may have been based? Is it possible they got airborne with the flaps closed and cooked things?

Cold Weather Operations
Below –23°C the cowl flaps should be closed soon after the engine fires regularly, as they will assist in raising the cylinder head and oil temperatures. When either the oil temperature reaches 70°C or the cylinder head temperature reaches 170°C the cowl flaps should then be opened.

Regardless of the degree of cold weather encountered, the cowl flaps should be opened one third (10°) for take off.

there was a great deal about the official history of the Kee Bird that I found to be erroneous

And that's why historians will never be out of a job. Even the participants in an event come away with differing perceptions as to what went on quite often.

[swordfish41]

Brian.
No. What I think was that it was so cold that once the aircrfat had started its takeoff run the engine temperatures dropped. Thad Dulin, one of the flight engineers on Fifi was in the engineers seat when the Kee Bird started moving, be interesting to talk to him. But if you are prepared to wait a couple of days I will try to hunt out the book I am refering to. Seems we are the only people interested in this thread so I might pm you.
sf41

[henry crun]

swordfish41: You are not the only ones, there are other like myself who find this thread interesting but do not know enough to comment intelligently, so please continue to post in public.

[FunkyStick]

very cold

<<Regardless of the degree of cold weather encountered, the cowl flaps should be opened one third (10°) for take off.>>

......this is a minor point in the grand scheme of things, but in hours of conversation with the co-pilot of a B-29/F-13 that crashed in Fairbanks due to the intense cold during takeoff, I was told that after his crash cowl flaps were to be kept closed during intense cold operations. The temp where the cowls were to be completely closed escapes my memory at the moment... but I know at -30 in Fairbanks strange things start happening to cars and trucks. At -20, my cameras stopped working regardless of how warm the batteries were.

On this particular crash during the night of December 11, 1946 it was so cold (-57F) that the fuel didn't vaporize and so there was no initial explosion. The copilot literally unbuckled and walked away because so much of the cockpit around him was gone. As the temperatures increased during the day, the fuel began vaporizing and a significant fire erupted eventually reducing the wreck to a smoking hulk.

It needs to be pointed out that at the time, B-29/F-13 operations in that kind of cold had not been experienced. The crash I just described was the first for the squadron. Despite its recon mission, the squadron was something of an Arctic guinea pig and the "book" had to be modified to reflect local operating conditions.

In an interesting bit of trivia, the Kee Bird successfully took off moments behind the crashed aircraft and unknowingly overflew the crash because of ice fog in the area. The pilot of the crashed aircraft would eventually be part of the crew of the Kee Bird when it went down in Greenland.

[swordfish41]

I'm about to go and search for the book about the Kee Birds Squadron, but Funky Sticks post chimes very well with what I remember. I have a feeling that in fact there were three crashes all told before it was realised that the cowl flap settings might be a contributory factor.
sf41

[swordfish41]

Well that was a wasted three hours. I am afraid after searching through boxes of production files I couldn't find the book I was looking for. Funky sticks account of what happened in Fairbanks is going to have to be the best source for the effect of cold on the B29. Not sure the original question of this thread has been answered.
sf41

[stepwilk]

Actually, I got a very good answer to the original thread question, which I posed, from an acquaintance who saw it and answered me privately by e-mail.

In short, the answer is that the R-3350 was an incredibly fuel-economical engine--probably one reason it had such cooling problems, since it was burning no extra gas for combustion-chamber cooling--and my friend had done a number of SFC calculations for various R-3350-versus-R-2800 situations that showed that only at very low power settings did the R-2800 fuel economy match and slightly exceed the R-3350's. In order to come anywhere near matching the R-3350's typical mission output, the R-2800 would have had to burn substantially more fuel and the B-29 would no longer have been a very-long-range bomber.

[swordfish41]

I had no idea that the B29 was considered to be unreliable, or indeed what that means. I have just written a book about a Lancaster bomber crew, who in their first thirty missions experienced four seperate engine failures, (RR Merlins) involving five individual engines. The flight engineer didn't seem to think this was out of the ordinary, and I suppose it wasn't.
sf41

[stepwilk]

The standard joke was that Curtiss-Wright killed more B-29 crewmen than did the Japanese. Unfortunately, it wasn't a joke: 147 B-29s were lost to enemy fire, and 267 were lost to "operational causes"--typically engine fires and failures that led to either the destruction of the airplane in the air or crashes on overloaded takeoffs. Do the math and that shows that nearly two B-29s were lost because the airplane was basically unreliable to every one lost to Japanese fighters or antiaircraft.

[swordfish41]

Point taken

[Jhieminga]

Originally Posted by stepwilk

Let me ask, before printing something stupid: are we all convinced that Rory57 is correct in posting, above, that the B-29's cowl "could not be removed to allow engine maintenance without first removing the propeller"?

I'm looking at a B-29 photo, a general shot and not a nacelle closeup, that seems to me to show enough Dzus fasteners to remove the forwardmost cowling section, and certainly the panels aft of that.

I finally got around to finding the relevant book "B-29 Superfortress in detail and scale, part 1", by Alwyn T. Lloyd (which is the only B-29 book I've got at the moment). From page 17:

The cowlings were comprised of a fixed cowl ring, a set of side panels, and ten moveable cowl flaps. On early engines, the propellor, cowl ring, and side panels had to be removed in order to change the 36 spark plugs. Later cowls were manufactured with removeable side panels - a feature which was also retrofitted.

And on page 47:


There are some photos in the book of early B-29s and they do not appear to have the dzus fasteners on the cowling side panels. The photos are not clear enough to be certain but I'm inclined to believe it. Here is no.2 engine from a YB-29:

[Brian Abraham]

Thanks for that Jhieminga, I must confess I find it hard to believe that the Americans, with all their experience to draw on, and engineering talent, would put out such a bastard child maintenance wise.

[Rhino1]

You might check and post the question on the Warbirds Information Exchange (WIX to many). There are several guys there who work on FIFI.

Ryan

[Brian Abraham]

Unlike a turbo charger a power recovery turbine has a coupling to the crankshaft. That is, instead of the turbine driving a compressor to pump air to the cylinders it is connected to the crankshaft.