Heating, ventilating, and comfort in WW2-era combat aircraft

I remember seeing a documentary once were a man was throwing matches into a bucket of incredibly powerful aviation fuel (I think it was from the SR71 but not sure) anyhow he was proving that as strong as the stuff was a naked flame wouldn't light it. Can anyone refresh my memory on this?

I think people are confusing several different things.

ALL aviation gasoline has just about the same number of BTUs per gallon or the same amount of stored energy per gallon. What changes with higher octane is the auto ignition temperature, the temperature at which the fuel vapor will ignite in the absence
of a spark or open flame. The temperature at which it will ignite with a spark or open flame may vary too but that is not measured by octane rating.

Jet fuel or kerosene may have more BTUs per gallon (more powerful?) but has a much higher auto ignition temperature. However, since the liquid (either gasoline or kerosene) DOES NOT BURN, only the vapors burn, we have another factor. Gasoline will form vapors at 40 degrees below zero, slowly, but it will. Kerosene will not form vapors until some point between 100-200 degrees F depending on grade. You can throw matches at a bucket of 70 degree kerosene all day long and get nothing. Spill a few gallons on a blacktop road in the middle of summer and you have a whole new story.

swampyankee said:

Don't forget the oxygen system. I'm sure there were fighter pilots who smoked; I suspect that the number who smoked when at 20,000 ft on oxygen was roughly nil.

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True, remember a story about one RAF pilot, who made a habit of descending to smoke his pipe on the way back from missions over France ... until he was shot down by flak by being too low that was....

But the other comment was right, if you were on the pointy end (land sea or air) smoking was a very low risk factor in terms of mortality.

If you were one of the real high risk ones (like a U-boat crew) then smoke, drink, drug yourself all you want ... cause none of them are going to kill you first.

Well, people will smoke even when there is a high probability of immediate harm, like building ledges when smoking was banned in offices, or while on home oxygen. One of my doctors has taken care of patients with burns radiating from their nose and mouth due to smoking while on oxygen. Presumable combat pilots are smarter than that. Disregarding fire and flame from fumes, I believe that research from that time had found that smoking impaired human performance at altitude and human vision, especially night vision (completely ignoring the direct affects on night adaptation by the flare of a match), so I would think that it would be discouraged.

All grades of petroleum/gasoline have a flash point, that is the temperature at which vapours are produced capable of making an ignitable mixture in air, well below zero celsius. Unless your cockpit temperature is below about -20 degrees celsius, whatever the octane rating of your fuel, the potential for going up in a fire ball when you strike that match exists.

Kerosene, Diesel and jet fuels have flash points in the region of +40 to +60 degrees Celsius, depending on their composition. That's why at normal ambient temperatures you can chuck a lighted match into the stuff with no fire or explosion. The ignitable vapour/air mixture is not present.

Smoking attenuates the amount of oxygen that diffuses from the lung tissue and oxygenates the blood. High altitude attenuates the amount of oxygen available for transport to the blood. A 2003 study suggested that these two hypoxic conditions react exponentially to affect human performance. The study concluded that "the combined hypoxic effects of smoking and high altitude result in a statistically significant detriment in pilot effective performance."

Don't smoke and fly at high altitude, or climb Everest. In fact just don't smoke!

Cheers

Steve

pattle said:

I remember seeing a documentary once were a man was throwing matches into a bucket of incredibly powerful aviation fuel (I think it was from the SR71 but not sure) anyhow he was proving that as strong as the stuff was a naked flame wouldn't light it. Can anyone refresh my memory on this?

Click to expand...

JP-7 - it has a high flash point and the SR-71 used triethylborane for ignition.

So in my very limited experience here is what I can add - hope it is worth something.
The B-17 can be down right HOT sitting on the ramp in 80 degree weather. In the nose with the all the plexi it feels even warmer. Once you take off everything gets far more comfortable. Now mind you this is flying in the U.S. in the summer at about 5000' or so - certainly not high altitude. I can only imagine how cold it would get even in the mid-day sun. It is loud but not incredibly so and typically no one needs hearing protection unless you want to take a snooze then that helps so I am told.
The B-29 is a pretty nice ride compared to the B-17. The caveat here is again my expereience is in FIFI and she does not fly high altitude and is configured differently than a wartime B-29 would have been, In the nose it can get pretty warm on the ramp with all that plexiglass. But it seems to me with the insulation in the nose that the overall temp of the cockpit is a little cooler. In flight it again seemed to me that the temp was a little more stable. There seems to be more room to move around AND if you make your way to the back there is (or was) a nice bucket for your "hero's duty" - not so in the B-17!

The other plane that comes to mind is the Grumman TBM. In a TBM turret you are "Backwards into battle" to steal a line form Andy Doty. On the ramp it is hot and cramped. Once the engine is started it cools off and other than being a bit cramped quite nice. Although it took me a bit to get used to flying backwards. I can only imagine how loud the 0.50 would be when fired as it sits practically right next to you. Wind noise is nottoo bad and I would guess that since these planes were Navy torpedo bombers that a lot of high altitude flight was not done (someone enlighten me here please) but if so I would think that it got cold in a real hurry without a heated suit and gloves.

My .02

Tom P.

I just reread Clash of Eagles, about the 8th AFs bombing effort in WW2 .

I was surprised about how often crew members had incidents with their oxygen systems. Many more men would have died if not for constant intercom checks on all the crew. If someone didn't check in another crew member was sent to check them out. Often their oxygen system had become defective for some reason or another, and they were unconscious.
Also crew members would get frostbite when giving first aid to other crew, or doing other task that couldn't be performed with thick gloves on.

I know that the USAAF had problems with icing in the oxygen mask or its supply lines.
Cheers
Steve