Sunday, December 25, 2011

Thick & Thin.

This is coolbert:

"Asking the detectives!"

In a recent episode of the PBS television program "History Detectives" Wes Cowan is researching and attempting to return to a living relative a World War Two [WW2] diary as written by an American combat aviator of that conflict.

That diary coming to an abrupt end the author Bill Moran, the co-pilot an American B-24 bomber during WW2 killed-in-action during a mission, Wes nonetheless using the investigative techniques of the history detective able to locate, and return the diary to the daughter of Bill Moran after a period of almost seventy years!!

"Investigations WWII Diary"

That American B-24 Liberator bomber having a formidable capability but referred to by the aircrews as THE FLYING COFFIN!!

"The liberator [B-24] earns itself another more ominous nickname – the flying coffin – due to the high casualty rate among B-24 pilots. Why were these missions so deadly [?]"

The B-24 a more able and capable bomber aircraft [than the B-17], able to carry a larger bomb load further and faster. Three times the bomb load of a B-17! [this is to be anticipated, aeronautical theory and design concepts just in seven years being more advanced, the engines available too more powerful!]

"A B-24 flew faster, farther, longer with a 3 ton larger load than the B-17s ever could"

The B-24, however, in contrast to the B-17 bomber MORE susceptible to shoot-down?

That B-17 as described in a previous blog entry being very robust and able to sustain a lot of combat damage while maintaining air-worthiness, continue the mission, return to base. ROBUST IN A WAY THE B-24 WAS NOT?

[this is not to say the B-17 could not be shot down, but rather was robust and was able to sustain a lot of damage. Prodigious number of the B-17 were shot-down during the war nonetheless, the consensus opinion however I would think being that that the B-17 was indeed a "tough bird"!]

The B-17 was robust and the B-24 WAS NOT?

And thanks to the web site: "The Great B-17 – B-24 Controversy" we have the answer!

The answer in a nutshell is thick versus thin. The B-17 having a "thick" wing as compared to the B-24.

"Boeing company came up with a design - using 1932 technology - to take a 1 1/2 tonne load over 400 miles to a target and return . . ."

"The B-17 design team then had to use a wing that would lift a LOT of weight on what horsepower available - and that mean a thick wing that generates a LOT of lift - ."

The B-17 wing is a pre-war era design and is THICK for heavy lift efficiency. The power of the engines available dictated this thick wing design.

"The design team [B-24] choose a wing - the 'Davis' wing - that is thinner when compared to the B-17 but generates more lift."  [this original design as of January, 1939]

"That thin wing of the B-24 requiring less material support and shoring, that point of contact where the wing meets the fuselage being LESS robust than the similar construction of the B-17!"

"The thinner wing by 1930 design standards means a less strong wing. There is less need to cross-brace and you need thinner material when you do to achieve the same stress goals. The B-17 being a thicker wing needed more - stronger - material to support the wing and thus had to be designed stronger. So in combat this helped the B-17."

"a few shells in the smaller wing cross section would cause the wing to fail faster than the much longer chord, and thicker, B-17 wing"

The B-17 able to take more hits of a worse nature, survive, keep going, remain intact, not fall apart, absorb damage and continue to fight.

[again that is not to say the B-17 was impervious. Merely relatively impervious. Able to take more damage and continue with the mission!]

Thick and thin. Greater range, faster, more bomb load or more robustness. Take your pick. Aircraft design was then and is now and always will be a compromise.


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