B17 Flying Fortress.
Discussion
It was all to do with operating effectively at high altitude. Most heavy bombers of that era never ventured much above 20,000 feet. RAF Bombers generally operated between 10,000 and 17,000 feet. A Stirling with a full bomb load struggled to get above 14,000.
Both the B-17 and the later B-24 were designed to operate around 30,000 feet. They weren't pressurised so it was very uncomfortable for the crews, especially when perspex panels were opened or removed to allow the defensive guns to be operated.
They also carried the Norden bomb sight - which was designed to enable accurate bombing from 30,000 feet. Of course, when these aircraft and their technology were exposed to the real conditions of warfare, not all the technology lived up to the expectations.
Both the B-17 and the later B-24 were designed to operate around 30,000 feet. They weren't pressurised so it was very uncomfortable for the crews, especially when perspex panels were opened or removed to allow the defensive guns to be operated.
They also carried the Norden bomb sight - which was designed to enable accurate bombing from 30,000 feet. Of course, when these aircraft and their technology were exposed to the real conditions of warfare, not all the technology lived up to the expectations.
Yes - I was getting confused. Later American engines used even more advanced derivatives of this technology and were known as Turbo Compound engines.
The Americans were very keen on turbo technology in their aircraft and it was also fitted to the Lockheed P-38 Lightning and the Republic P-47 Thunderbolt.
The Americans were very keen on turbo technology in their aircraft and it was also fitted to the Lockheed P-38 Lightning and the Republic P-47 Thunderbolt.
Eric Mc said:
I presume you mean the Sperry Ball Turret 
The Lancaster traded space for crew with space for bomb load.
Probably! My father's attempts to get me into planes never really worked as I always preferred boats.The Lancaster traded space for crew with space for bomb load.
He knew the chaps who had restored the Sally B and I went on board at Biggin Hill around 1979 or 1980 I think. I do remember that even as a 7-8 year old, I had to really squeeze through the entry to the Lancaster cockpit.
Sally B wasn't "restored" in the traditional sense. She was fully airworthy when she was acquired from the French Institute Geographique (in 1975) who had been using it (as well as a few other B-17s) as geophysical survey aircraft. Over the years, she was brought back to a more wartime configuration.
Eric Mc said:
Sally B wasn't "restored" in the traditional sense. She was fully airworthy when she was acquired from the French Institute Geographique (in 1975) who had been using it (as well as a few other B-17s) as geophysical survey aircraft. Over the years, she was brought back to a more wartime configuration.
Ah - I stand corrected. It would have been the guys who got her into 'wartime mode' then. All I remember is a lot of men in fur-lined flying jackets!She went through various permutations in her career.
When she first arrived in the UK she was in bare aluminium and the main "restoration" required was the application of USAAF markings.
A couple of years later a remote control chin turret was added to make her look more like a wartime B-17G.
By 1984 the aircraft had been repainted in dark olive drab/neutral gray colours - which was the norm for B-17s up until early 1944 or thereabouts.
In 1989 she one of the B-17s used in the film "Memphis Belle" and was repainted in a lighter shade of olive drab and received markings to make her look like the original Memphis Belle (the original Memphis Belle was a B-17F - which didn't have the chin turret.
She has carried those colours ever since.
When she first arrived in the UK she was in bare aluminium and the main "restoration" required was the application of USAAF markings.
A couple of years later a remote control chin turret was added to make her look more like a wartime B-17G.
By 1984 the aircraft had been repainted in dark olive drab/neutral gray colours - which was the norm for B-17s up until early 1944 or thereabouts.
In 1989 she one of the B-17s used in the film "Memphis Belle" and was repainted in a lighter shade of olive drab and received markings to make her look like the original Memphis Belle (the original Memphis Belle was a B-17F - which didn't have the chin turret.
She has carried those colours ever since.
lufbramatt said:
I think there may have been another airworthy b17 in the uk in the mid eighties? My dad has photos of a bare metal b17 taken at either west mailing or manston, with me in the photo, and i was born in 1984.
That would have been G-FORT - http://www.airliners.net/photo/Boeing-B-17G-Flying..."G-FORT (cn 8627) Built in 1945 for the USAAF as 44-85718. Seen here with it's previous identity F-BEEC of the Institut Geographique National still visible on the fuselage sides. It was registered to Fairoaks Aviation Services Limited in April 1984 and operated with Doug Arnold's Warbirds of GB Ltd. It can now be found at the Lone Star Flight Museum, Galveston, Texas as N900RW. "
Colour image as G-FORT - http://i22.photobucket.com/albums/b304/vultee35/ol...
Eric Mc said:
It was all to do with operating effectively at high altitude. Most heavy bombers of that era never ventured much above 20,000 feet. RAF Bombers generally operated between 10,000 and 17,000 feet. A Stirling with a full bomb load struggled to get above 14,000.
Both the B-17 and the later B-24 were designed to operate around 30,000 feet. They weren't pressurised so it was very uncomfortable for the crews, especially when perspex panels were opened or removed to allow the defensive guns to be operated.
They also carried the Norden bomb sight - which was designed to enable accurate bombing from 30,000 feet. Of course, when these aircraft and their technology were exposed to the real conditions of warfare, not all the technology lived up to the expectations.
The advantage of a turbo is that as the compressor and turbine are coupled together they have a much wider range of operation than a supercharger. The supercharger is a radial compressor on a shaft it is essentially linked with a fixed ratio to crank. At low altitude you have to limit the boost to avoid detonation, hence all the exotic high octane petrol. Both the B-17 and the later B-24 were designed to operate around 30,000 feet. They weren't pressurised so it was very uncomfortable for the crews, especially when perspex panels were opened or removed to allow the defensive guns to be operated.
They also carried the Norden bomb sight - which was designed to enable accurate bombing from 30,000 feet. Of course, when these aircraft and their technology were exposed to the real conditions of warfare, not all the technology lived up to the expectations.
At high altitude the air is cold and less dense you can compress it more without worrying about detonation. Hence why late war Merlins had two speed superchargers over 10-15,000ft you flipped them into a higher gear.
On the turbo if the compressor is deloaded it will spin faster compress more gas and then this fed through the engine which then drives the compressor harder. Across a working range the turbo is essentially a variable speed drive.
Most importantly a turbo is more thermodynamically efficient since you are doing the compression with energy extracted from the exhaust. RR did some trade studies on supercharger vs the turbocharger the turbo is more efficient but the packaging is more bulky (draggy) and on a high speed aircraft the supercharger exhaust can be converted into direct jet thrust which offsets the loss of running the compressor off the crank. Obviously this equation changes somewhat on a slow bomber like a B17, plus "does this technology buy its way on the engine" is the bane of RR.
The argument was rendered moot before ever more complicated turbo and superchargers were ever constructed.
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