The Slow but Steady Boeing B-17 "Flying Fortress"

The Boeing B-17 four-engine heavy bomber was a fairly slow, limited-capacity prewar design used more than newer designs due its ability to get its crew home when all other designs would have fallen apart, burned up or blown up after typical mid-war Luftwaffe fighter attacks.
 


Memphis BelleThe restored B-17E (no nose turret) used in the Hollywood version of the Memphis Belle story, backfiring upon startup.


 


Its extra wing area also made it more stable than others for accuracy-requiring high altitude strategic bomb drops with the Norton bombsight.  To try to help counter its slow speed and low (long-range mission, at least) payload, water injection, injected right after the point of ignition, was sometimes used on takeoff.  That design approach often simply caused the literally exploding water vapor to blow off cylinder heads.

Thanks to the Confederate Air Force's including the Capitol City Airport in Harrisburg, PA in their B-17 "Sentimental Journey" and He111 tour, I have lots of interesting pictures of those two planes...

You can click on the better pictures (with the blue frame) to get a larger (2X) version, or see the picture's specific detail area in close in the nose turret picture.

Both left engines on startup
1200hp Pratt & Whitney R-1820s during startup 

The burning oil smoke is actually normal - the oil control rings hadn't seated yet from seeing enough combustion.  Notice that near right engine, which had just started by burning oil itself, is now idling with its oil control rings properly seated.

The vague, small dorsal fin type shape behind the rudder is the rudder of the Heinkel 111 also there.  That He111 is currently the only flying example in the world, and was the personal escort plane of General Franco during the Spanish Civil War.

The smaller reflective pool directly under the far right engine in the top picture is avgas, from the engine flooding during its not starting.  The guys standing in front of the plane are both holding a fire extinguisher.  During the start attempt the nearer guy he had it up and aimed right at the engine as a "just in case" precaution.

Going, going? 
Back again! 

After having trouble starting the far right (from pilot's view) engine, and probably not being pleased with its preflight run-up performance check, after pausing at the runway they turned the ship around and came back to work on that engine.

A magnificent bird; details everywhere 
Fuel intake & adjustment pulley (top) 
A flightworthy R-1820 (starter: OFF!) 
Similar to P-38's turbocharger design 
2 tons ordinance in long missions 
The short guy in here always 
Needed to keep frontal attacks at bay (and yes, those are zippers) 
Magneto trouble finally over 

The whitish swirls in the propwash are from water condensing at the prop tips, from the extreme tip-area vacuum caused by a full 1200hp turning the prop blades in mist conditions.  It's the same effect that caused the water vapor to condense above the MiG 29's wings in the picture in Climbing the Sky.

In case you're wondering and didn't know, this is a G-series as shown by its having a chin gun turret.  From Joe Baugher's very massive American Military Aircraft Encyclopedia, from the B-17B on the engines are Wright R-1820 single-row Cyclone radials.  For the G series, the R-1820-97 was used with General Electric B-22 turbochargers capable of about 23,000rpm to provide 1380 hp peak war emergency power at up to 26,700ft (the impellors would overspeed beyond that height at the required manifold pressure).  According to someone at the fly-in, the massive exposed turbochargers would glow orange at normal cruise speeds from the hot exhaust backpressure, despite being directly cooled by propwash.  The R-1820-97 is rated for 1200hp for takeoff and 1000hp max. continuous at 25,000ft.

From what I overheard, there was a magneto problem of some sort causing the far right engine slowness.  The contact gap may have been too wide, for I heard a crewman say "The book calls for 1/1000th of an inch.  Hell, you can't even see that.  Water could close that."  From what I heard, they settled for 3/1000th of an inch, which it fired up instantly with.

The Boeing B-17 Flying Fortress is an absolutely magnificent, and huge, bird.  As I wrote to the Aircraft Discussion List shortly after the encounter, the sights, sounds and smells of just its warmup are practically enough to start a cult.

These birds are very expensive to maintain.  Flying time costs about $2,000 per hour.  If you ever read of one of the ten of these left, or another precious old warbird in your area, go see it and please be generous with your contribution to the Confederate Air Force, which does the flights and owns the planes.

Do you know how it feels to find yourself pondering something with your finger against your teeth, to then realize you are tasting a B-17 in action?  It's cool.  Very cool.


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