Fortress versus Lightning: B-17 and F-35 compared

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The Boeing B-17 and Lockheed Martin F-35 are two American bombers separated by around 70 years of history. They belong to the same weight class and bear interesting comparison.

First flight:

B-17 1935

X-35 2000 / F-35 2006

Time from requirement to service entry:

B-17 4 years (1934-1938)

F-35 23 years  (1992-2015 est. for B)

Performance

Maximum speed compared to average contemporary fighter:

B-17

287 mph/400 mph (71.75 %)

F-35

1200 mph/1450 mph (82.7 %)

Range:

B-17G:  1,738 nmi, 3219 km with 2700 kg (6,000 lb) bomb-load

F-35: 584 nm (1080 km) on internal fuel (combat radius)

Take-off speed:

B-17: 115 mph

F-35: 0 mph (B variant)

Maximum conceivable amount of enemy aircraft that can be destroyed by standard defensive weapons on one mission

F-35: 2

B-17G: 25+

Loads

Max loaded weight:

B-17G: 65K Ib

F-35: 70K Ib

Max internal bomb-load:

F-35: 4670 lbs

B-17: 8000 lbs (4500 lbs for long range missions)

Max bomb-load (including external munitions):

B-17: 17, 600 lbs

F-35: 18,000 Ibs

Max internal fuel:

F-35: 19,200 lb (C model)

B-17: 10, 200 lbs

Wing loading

F-35: 107.7 lb/ft² (526 kg/m²; 745 kg/m² max loaded)

B-17G: 38.0 lb/ft² (185.7 kg/m2)

Cost

B-17: $238,329

F-35: $170 million (flyaway average A/B/C 2013)

How many bottles of coke* could you buy with the cost of each aircraft (contemporary prices)?

F-35 is worth 113,333,333 cokes an aircraft.

B-17 was worth 4,766,580 cokes an aircraft in 1943.

The $238,329 it cost to build a B-17 would be worth $3,209,272.19 today.

*based on bottle of Coca-Cola (1943): 5 cents, (2014): $1.50

The last turbojet: the tale of the Lyulka AL-21

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The turbojet is an endangered species–  so what aircraft are left that still use it? It is easy to think of the dwindling MiG-21 populations, and at a push the EA-6B – but you may be surprised to recall that the Su-24 and Su-25 both have turbojet engines. The ground attack mission, with its frequent long range and low-level operations would seem to necessitate the use of turbofans. So while the West used turbofans on the A-7, Tornado, F-111, A-10 and F-15E, why on earth would the Soviet Union use fuel-thirsty turbojets on their equivalent aircraft? One reason why they employ this seemingly archaic powerplant is the turbojet’s unfussy tolerance of any kind of fuel, a blessing in the event of fuel shortages in war. The Su-25’s R-95Sh was designed to be able to run using different fuels, it can even run for four hours on ground vehicle diesel. 

The turbojet aircraft that has dominated the news this year has been the Su-25, but it is the engine of the Su-24 that we are looking at today, the Lyulka AL-21. Designed by Ukrainian Arkhip M. Lyul’ka in 1959-60, the AL-21 is a turbojet with a 14-stage axial compressor with variable stator blades. This engine powered the Sukhoi Su-17, the Su-24, early MiG-23s and (as a non-reheated variant) the Yak-38. The engine also powered the Sukhoi T-10, an aircraft that became with many modifications, the famous Su-27 ‘Flanker’. By 1982 nine ‘Flanker-A’ prototypes had flown, seven with AL-21F-3A1s and only two with Al-31Fs. 

The AL-31F which powered the definitive Su-27 was based on the AL-21F-3 which powered the Su-17/20 and the Su-24. It is interesting to note that Lyul’ka was aware of the turbofan concept as early as the 1950s, but politics got in the way of him being able to apply these theories in practice. Russian-born Dr. Pavel Aleksandrovich Soloviev was in a better position and it was his D-20P that became the first turbofan to enter service. The D-20P-equipped Tupolev Tu-124 entered service on 2nd October 1962 as the world’s first turbofan airliner. Today almost all jetliners are turbofans.

Another Su-25 shot down today

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Another Ukrainian Su-25 downed

In an age supposedly dominated by high technology, the warplane involved in more headlines than any other in 2014 is the simple Sukhoi Su-25. This aircraft is an armoured close air support developed by the Soviet Union and remains in widespread use around the world. 

Iraq

When the Iraqi government forces urgently required close air support they turned to the Su-25; Iran obligingly giving back the airframes they ‘confiscated’ from when they claimed asylum to operate alongside ex-Russian aircraft which were delivered with alacrity to aid the fight against ISIS (though in the event the Iraq air force didn’t have the experience to operate them). 

Russo-Ukraine War

In 26th May, Ukrainian Su-25s supported Mi-24s helicopters during a military operation to regain control over the airport in Donetsk, during which the Su-25s fired air to ground rockets. On 2nd July 2014, a Ukrainian Su-25 crashed due to a technical fault.

According to Russian new agencies and western anti-globalisation websites, the Malaysian Airlines 777MH17 was shot-down by a Ukrainian Su-25. The Western view is that it was downed mistakenly by pro-Russian forces with a Buk surface-based defence system. 

On 16th another Su-25 was shot down. Ukrainians claim it was shot down by a Russian MiG-29 fighter with a R-27T missile, allegations which the Russian government have denied. On 23rd July 2014, two Su-25s were shot down in the Donetsk region of Ukraine. A spokesperson from the National Security and Defense Council of Ukraine stated that the planes were shot down by missiles fired from Russia. Another Ukrainian Su-25 single-seat fighter was shot down today by pro-Russian forces over Luhansk Oblast in eastern Ukraine (August 20th).

The Hush-Kit aviation forum is now open!

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I wanted to set up an aviation forum freed from the tiresome ranting and gobbledegook that plagues most sites- so I did. If you’d like to get involved in well-informed polite debates on aviation subjects of any kind, then click here and get posting. I very much look forward to hearing from you.