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BG Archive
— Airlifter Comparisons — Boeing C-17 ( CC-177 ) |
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Globemaster III – the ’Lifter from Long Beach
The C-17 is descended from McDonnell Douglas’ mid-1970s YC-15 designed to replace the Hercules.
In the 1980s this design was resurrected to answer a new USAF CX (Cargo Experimental) requirement. Re-engined
and enlarged, the impressive C-17 was meant to supply the USAF with a strategic airlifter which could carry more
than a C-141 but also had tactical capabilities that were lacking in the C-5.[1]
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The C-17 is powered by military versions of the high-bypass turbofan engine used by the Boeing 757 jetliner.
The designers at McDonnell Douglas also incorporated systems from their own DC-10 jetliners to try to
curb costs. But, even by Cold War standards, the C-17s’ per unit costs were staggeringly high,
delaying service entry until well after the 1990/1991 Gulf War.[2]
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Boeing (McDonnell Douglas) C-17
— Specifications
| Powerplant: |
4 x 185 kN P&W PW2040 (military F117) |
| Cargo hold: |
volume 592 cubic metres |
| Hold dimensions: |
26.8m L x 5.5m W x 3.8m (max 4.1m) H |
| Carrying capacity: |
max payload 77t (max gross takeoff 265t) |
| Maximum range: |
5185km (unrefuelled, with 72t payload) |
| Ferry range: |
No cargo, maximum fuel supply 8710km |
| Speed range: |
max cruise (low alt.) 833km/h (Mach .74) |
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Rough Fields and a STOL Performance
Like other strategic airlifters, the C-17 has a multi-wheeled undercarriage allowing it to operate from
semi-prepared strips. The C-17 also has a host of high-lift devices – full-span leading edge slats and
titanium- covered flaps ‘blown’ by engine exhaust. Once down on the ground, lift-dumping spoilers
– deployed, above right – and engine thrust-reversers keep a C-17 down.
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The C-17s are impressive aircraft and hands-down CF favourite. C-17s are also phenomenonally expensive
– the USAF C-17A fleet averaged US$241M per aircraft. Constant US government pressure reduced that
price slightly but these numbers vary depending on what is being counted. DND originally estimated the cost of 6
C-17s at $1-to-$1.6B.[3] But the cost given for the new Airlift Capability Program-Strategic is $3.4B for only 4
C-17s (or US$762.5M each) due to a 20 year maintenance deal. Current USAF C-17 unit cost is
US$330.8M including training and spares.
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[1] The Cold War concept was to reinforce European forces in the initial phases of combat. Once
supply alternatives had been established (sealift, Civilian Reserve Air Fleet, etc.), the Globemaster IIIs
would shift to an in-theatre role augmenting the Hercules tactical transports.
[2] In May 1990, then-Defense Secretary Dick Cheney cut the USAF C-17 order from 210 aircraft to just
120 as a cost-saving measure. This resulted in a per unit price jump from the original US$178M up to US$294M. By
1992/93 abandoning the C-17 (in favour of new-production C-5 Galaxys) was being given serious consideration.
These difficulties with the C-17 program contributed to MDC’s take-over by Boeing.
[3] To put these numbers into perspective, a new-production Ilyushin IL-76
airlifter (with western engines and avionics) would likely cost no more than US$55M each (Russia threatened to move
the production line when unit costs began to creep) one fouth the price of a C-17.
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