War History Online proudly presents this Guest Piece from Hans Wiesman
In
this DAKOTA HUNTER Blog, you can read about the ultimate, most
stretched version of Boeing’s successful Bomber B-29 that had delivered
the World’s first Atomic Bombs in early August 1945.
The Empire of
the Sun stumbled on its feet and within a week, the beaten nation
surrendered unconditionally, having no more answer or defense against
such destructive power.
That final attack on Japan propelled the
B-29 bomber straight into the “Aviation Hall of Fame”, along with other
allied fighters, bombers, and transports as the P-51 Mustang, the B-17
Flying Fortress, the B-24 Liberator, B-25 Mitchell, the Douglas C-47,
the P-38 Lightning, the P-47 Thunderbolt, to name a few. Photo
above: By the end of the war, Boeing had delivered a huge fleet of
B-29s that operated from the tiny Marianas Islands in the central
Pacific. The conquering of those small islands Saipan, Guam, and Tinian
in July/ August 1944 was the perfect strategic move to shorten the
Pacific War. Combined with the extended flight range of the brand new
long distance bomber B-29 that could fly as far as 3250 miles. it
brought the Japanese main islands and cities directly within range for
their bombing assaults. See my earlier Dakota Hunter blog about the
Marianas here: B-29s from the MarianasSoon,
Boeing developed a more powerful version of the B-29 that was
originally equipped with 4 Wright aero-engines of the type R-3350, rated
at 2,200 hp per engine. The factory designated the new power boy as the
XB-44 with the all new and most powerful piston engines that existed at
that time, the Pratt & Whitney Wasp Major Radials R-4360.
This
XB-44 flew in May 1945 before the end of the Pacific War. The new
monster engines had 4 rows of 7 cylinders each, a total of 28 cylinders
in the “corn cob” configuration (see photo below). With 56 spark plugs
per engine, a nightmare for a mechanic in case the plugs fouled. The
huge 4360 cu in or 71,500 cc displacement per engine reflected also the
very end of the development line for the ever bigger Piston aero
engines.
Actually,
it was the arrival of the very fast but in limited series built German
Messerschmitt Me-262 interceptor/ fighter that heralded the new Jet Age.
(See photo at end of this Blog) Before the Jet engine came to a
widespread application in the post-war era, the aviation industry
entered a transition period between 1945 and 1955 in which the Turbojet
and Turboprop engines matured steadily toward such high thrust outputs
and reliability that they finally could push the huge radial piston
engines out of the market for bigger and faster aircraft. Photo
above: the P & W Wasp Major engine R-4360 could produce an output
of 3,500 hp with the mechanical superchargers, later came the
turbochargers, spinning on the exhaust gas flow of 71 liters of
displacement! Combined with the superchargers, this engine cranked out a
max. 3200 kW/ 4,300 hp per engine.When
comparing the ratio cc/ hp for the WWII aero-engines, we see the
mid-1930s developed Twin Wasp R-1830 by Pratt & Whitney (World’s
most produced radial engine that propelled the Douglas DC-3/ C-47, the
PBY Catalina, certain Helicopters and even Sherman Tank types) at max
1,200 hp. But 10 years later, there came this R-4360 with a max output
of 3,500-4,300 hp. The cc/hp ratio went from 35-40 hp per liter of
displacement to over 50-60 hp per liter.
In the modern automotive
industry with much smaller displacements from 1000-3000 cc, a ratio of
over 100 hp per liter is the norm by now. In competitions as F-1 and
Drag Racing that ratio goes far higher but is due to the (ultra) high
stress, only applicable for a short term of engine operations.
Fifty
years of large displacement piston engine development, it resulted in
an ultra complex engine as the radial R-4360 with a zillion of moving
parts and bearings, rods, gears. gaskets etc. all working in extreme
conditions under high mechanical and thermal stress. In the case of a
failure of one minuscule part, it could stop the gas guzzling monster
instantly or worse, make it explode.
She required a lot of
maintenance and even with all that hugging, many an R-4360 Wasp Major
was prone to in-flight fires and explosions, often due to overheating
caused by the very high temperatures of the 100-140 high-octane fuel and
the tight engine cowlings of the newer aircraft models that were wind
tunnel tested designs, all focused on optimizing the drag factor.
The
Wasp Majors R-4360s were produced between 1944 and 1955; 18,697 were
built and they were the very last of the huge piston props. That must
have been a relief for many a flight engineer or mechanic. But once
relegated to the support line in US Military Services, the aircraft with
big radial piston aero-engines could survive for many more years.
As
the flying tankers (KB/KC-series), personnel/ cargo carriers (MATS),
and early warning radar platforms (Lockheed EC-121 Warning Star) that
had no frontline or attack duties, the large Piston Props soldiered on
into the 1960s and early 1970s.
The KC-97 Stratofreighter tanker
and C-97 Transport (based on the B-29 design with similar wings but
double flight deck, see ad below) started their careers in 1950 with SAC
and the last of the KC-97s flying with the Texas and Utah Air National
Guard were phased out in 1978, far into the Jet Age while Jumbo and
Concorde already existed for years. Photo
above depicts a post-war ad by Boeing for its Stratocruiser B-377. The
aircraft had the wing design from the iconic B-29, but a double bubble
fuselage and the Pratt & Whitney Wasp Major R-4360 engines for
carrying bigger loads, more passengers and more fuel over longer
distances, up to 4,200 miles. But the aircraft was not successful in the
civil market: too complex, too expensive, and engines too capricious,
so in the end, only 55 were produced. Its competitors Douglas DC-6/DC-7
and Lockheed (Super) Constellation were built in much larger quantities
and ruled the skies between 1946-1960. By the end of the 1950s, Jet Age
arrived in full swing with the Boeing B-707 and the Douglas DC-8. End of
the story for the big piston props.
You
can read in this Blog about a most interesting development line of the
USAF long distance bombers from 1945-1955. A dynamic period of Blitz
style technological progress both in (pressurized) aircraft structures
and in aero-engine development from “Old School” Piston motors to
Hi-tech Jet Technology.
And last but not least in Weapons systems, Electronics, and Radar.
The Military aircraft was about to be reinvented by the end of WWII, a
Hi-Tech revolution was about to take place with those Jet engines,
pressurized cabins, swept wings and electric/ hydraulic flight controls. Photo
above depicts the B-50 Bomber that came out of the experimental XB-44.
Note the much larger engines and longer nacelles, the extended and
strengthened fuselage and underwing external fuel tanks. But the
original family silhouette of the B-29 is still intact. This
awesome photo above shows the tanker version of the B-50 in all its
glory. This is the KB-50J refueling from external pods a North American
FJ-4B Fury from VMA -214. Note that between the wingtip pods and the
outer piston engines, there are two more underwing bodies. They seem to
be Jet engines, mounted in a later upgraded version to get more top
speed for easier mid-air tanking operation with fast Jets hanging on the
“nipples”. The same was done on the B-36 Pacemaker that in initial
version had “only” 6 piston prop engines, while later 2 jet pods were
added for additional speed.Photo
above shows what was planned to become the top end of the stretched
B-29 line, the B-54 or the Best of the Boeing Bomber Family. But during
its development in 1947/48, Boeing ran with this aircraft design into a
weird struggle. The tunnel vision resulting in an exclusive
consideration of the evolution of existing technology, while a more
revolutionary technology at hand (but imported) was overlooked or
ignored.
Right after the war, the ‘invited expats from overseas” aka the
German Professors, they brought an advanced expertise of their Jet
fighters and bombers to the USA. The transfer of their technology was
most likely the killer for this seemingly “most modern” but virtually
“Old School” bomber B-54. It was USAF General Curtis LeMay who, due to a
far-reaching sight (or a good knowledge of that superior technology)
had the guts to kill the B-54 project.
That happened at an early stage with only a mockup built of the B-54
(see photos below). Luckily for Boeing, their management was not blind
and for acquiring that real cutting edge technology, they could tap the
‘recovered’ German resources as much as the other US manufacturers
could.
Soon, they must have found out that the TurboJet engine power in
combination with that swept wing concept was the true promise for the
future high-speed, high-altitude operating Intercontinental Bombers. In
hindsight, you can say that at best, the B-54 would only have been an
expensive stop-gap with a limited life cycle of 3-5 years in a decade in
which the pace of technological progress was more than awesome. Photo
above and below give some impressions of the mockup B-54 with the huge
gun pods on either side of the cockpit’s lower front end. The Machine
Gun “turrets” with eyeball setup were remote controlled units coupled to
a radar tracking system. The 1948 dated mockup of the cockpit below
shows a different layout with a radome on the higher left side and a
single Machine Gun or Radar housing/ pod on the lower front end. (Photo
courtesy Retromecanix.com)
The
photo above reflects best the stunning development in size of the
All-American Bomber between 1935 and 1948. In the left upper corner, we
see the pre-war Douglas B-18 Bolo (like the DC-3, based on the DC-2
design) that flew in 1936, along with its larger competitor the Boeing
B-17 Flying Fortress (in left front). The B-17 came back from the war as
an outright “Icon of Victory”.
By 1944, the B-29 entered the Pacific war theater and was 3 times
bigger than the Bolo. But within only a few years, that B-29
Superfortress was totally overshadowed in size by the Convair B-36
Peacemaker (center right). This strategic bomber was operated by the
USAF between 1948-1959. The largest Piston Prop aircraft ever built had
the longest wingspan, a whopping 7o m/ 230 ft. With a flight range of
10,000 miles and a max payload of almost 40 tons, it could haul for the
Strategic Air Command (SAC) all US Nuclear weapons of that time to any
place over the Globe, read including Moscow!
But
the B-36 Peacemaker career was also plagued by its six piston engines
R-4360s. Hilarious slogans as ” six turning, four burning” soon went
over to “two turning, two smoking, and two choking”. The engine problems
aggravated, related to the Pusher-Prop configuration of the B-36. In
the more standard tractor setup with Props running on the leading edge
of the wing, the carburetors in the rear end of the engine receive more
heat from the cylinders airflow.
Icing of Carbs in the harsh Alaskan climate often happened and one
day in 1950, with 3 engines on fire of a B-36 led to the first in-flight
loss of a US owned Nuclear Bomb. Later, Jet pods were added under the
wings for more take-off thrust and higher top speed in case of an
encounter with an enemy Jet interceptors. Click for more details of that
harrowing story my blog here Peacemaker B-36 crashing. Photo
above depicts Boeings first all-jet powered Bomber, the B-47 Stratojet.
This remarkable aircraft (with some remote German design features)
entered service in 1951 and would soon make the core of the Nuclear
Bomber Force of the USAF throughout the 1950’s. As a reconnaissance
aircraft, it flew until 1969! The bomber also had 18 rockets in the tail
for Jato starts (Jet assisted take-offs) when fully laden with bombs
and fuel.
In the B-47 design, only a minimal armament was provided, as its
speed and altitude were considered superior to any existing interceptor
in the late 1940s. But the bomber’s range was not sufficient to fly
independently from Continental USA over the USSR to Moscow. In-flight
refueling was the only option but made the bomber more vulnerable.
Worse, the appearance of the Mig-15 Interceptor/ fighter during the
Korean conflict (1950-1953) made it clear that even the fast B-47 would
never have a chance to accomplish a bomber mission over Russia to Moscow
without the escort of long range fighters! But the USA did not have the
fighters that could fly such distance at high altitude and high speed.
It was a setback that would soon be addressed in the next project, the
legendary B-52.
Finally, in the B-52 design, with some help of Luftwaffe technology,
the Jet Bomber came to full fruition with its swept wings and full jet
propulsion. The canceling of an extended B-29 design in the shape of a
B-54 UltraFortress was no longer a frustration. Instead, Boeing got a
superb Hi-Tech project in hands that would give them a technological
advance for decades in the construction of Big Aeroplanes with Jet
engines.
The result of this can be seen in the next photo of the Boeing B-52
and ultimately in the introduction in 1970 of the B-747 wide-body Jumbo
Jet of which now over 1,500 have been delivered (ult. 2016). Boeing B-52A (S/N 52-001) in flight. Note the external fuel tanks have been removed. (U.S. Air Force photo)
Photo above could be titled: “The Winner takes it all”. It shows the
first built Boeing B-52 Stratofortress that came in USAF service in
1955. Now 62 year later, the aircraft is still operational in numbers,
58 B-52H types are in active USAF service, with 18 more in reserve!
The bombers fly under Air Force Global Strike Command (AFGSC) and
were reactivated in bombing missions over Afghanistan in 2016, they flew
recently to Guam to support the S. Korean defense and over the Baltic
Sea supporting the minuscule ex-USSR Republics Latvia and Estonia. Not
so bad for an old soldier that fought in Vietnam in the 1960s and many
more wars.
With their 70,000 pounds/ 32,000 kg of weapons and a flight range of
8,800 miles/ 14,000 km without in-flight refueling, they still can fly
all around the globe, be it not over Russian territory. With their
subsonic top speed, they are vulnerable to advanced anti-aircraft
missiles. More modern aircraft as the supersonic B-1 Lancer and the
Stealth Bomber B-2 Spirit are better adapted for such ultra-secret
missions.
Its low operating costs with extremely reliable technology (being
upgraded every couple of years with the newest hi-tech), the USAF has
saved 76 vintage B-52 aircraft from the cutting torch. Way back in 2006,
I saw at Davis-Monthan AFB in Tucson, Arizona, the death row of
hundreds of dismantled B-52s waiting for the cutter, but even in 2017,
there is still a remarkable number that survived. Moreover, some of them
are expected to serve until 2040, another 23 years to go!
The B-52 belongs to that special breed of rare aircraft with a 50+
years career in a continuous service with its original operator or in US
Public service. In that league, you can count the members of honor on
the fingers of one hand. Next to the B-52, there is the Lockheed C-130
Hercules and its predecessor, the Douglas C-47, and derivated types.
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