The C-17 is a compromised beast, neither fish nor fowl, neither tactical nor strategic, jack-of-all-trades and master of none.
It’s great value is that it can be made to do most anything, but just because you can cut down a tree with a butcher knife doesn’t mean you should.
I will consider 3 different areas and show how the C-17 isn’t right for any of them
1. Tactical
This one is pretty obvious. It’s simply too big to get into many places. It can’t land on sandy surfaces. It can land on dirt, but only as a stunt. (The AF typically restricts it to paved surfaces). It doesn’t have enough landing gear and thus tears up soft surfaces to render them unusuable. Practically, turbofans are never a good solution on dirt because of FOD.
Fortunately, the US is well covered in this area with the C-130J and soon the C-27J
There may be a niche for an A400M/C-130XL type, but generally, we are/will be ok here
2. Pallet / Light cargo / aeromedical
Most cargo is shipped via pallets, but the C-17 basically sucks as a pallet hauler
a) Number of pallets
C-130: 6-8 pallets
C-17: 18 pallets
KC-30: 26 pallets on main deck + 6 lower deck (not full height)
C-5: 36 pallets
777: 37 pallets
747: 36 pallets main deck, 3-5 lower deck
b) Range
The C-17 is a fuel pig and by consequence limited in range
i) overweight
– tremendously overbuilt for light transport roles with a massive floor structure that supports tanks. When you don’t need such strength, it’s just so much dead weight that saps range
ii) aerodynamically inefficient
– the draggy external landing gear fairings are necessary for its ‘tactical’ role, but do nothing for it’s aerodynamic performance
– the rear cargo door is also a result of it’s tactical heritage, but again hurts aerodynamics
iii) too small
the C-5 faces many of the same challenges as the C-17 (overweight, poor aerodynamics), but overcomes them with size
– the C-17 pretends to be tactical so it has a small wing that enables it to fit into more places. The C-5 makes no such pretense and can thus have a much bigger, more efficient wing
– by being size limited, the C-17 simply doesn’t have room for enough gas. They made the C-17ER so it could finally hop over the Atlantic without refuelling, but the extra fuel tanks intrude into the cabin, further reducing its cargo flexibility. The C-5 is simply big enough that it can pack in enough gas to overcome its limitations
C-17: 160,000lbs 2420nm
C-17: 40,000lbs 5610nm
An-124: 240,000lb 2500nm
747: 220,000+lb 5000nm
A330: 6400nm (unknown payload)
777-200LR: 8865nm (unknown payload)
enhanced range A330 – 7866 miles (projected)
The C-17 just isn’t cut out for the Pacific, even getting to Hawaii with max payload is a stretch. And beyond that . . . fuhgeddaboutit
Travis (San Francisco)-HIK (Hickam AFB) – 2435 mi
HIK-Seoul – 4576 mi
HIK-Guam – 3801 mi
HIK-Kadena – 4652 mi
HIK-Taipei – 5069 mi
It will be severely weight limited to make to any number of probable destinations from Hawaii
A sample itinerary to the middle east doesn’t look much better
Dover-Ramstein – 3969 mi
Ramstein-Bagram – 3221 mi
If a long-distance delivery was required, it could easily take FOUR TIMES AS MANY FLIGHTS to accomplish the same mission as C-5s (2 C-17s for every C-5 and 1 tanker for each C-17)
c) Speed
C-17 – cruise speed: 450kt
A330 – economical cruising speed: 464kt
777 – typical cruising speed: 490kt
as an example of how these factors combine to hamper aeromedical evacuations consider this story:
http://www.airforcetimes.com/news/2007/02/apc17flight070211/
. . .
fly a Marine 7,500 miles from Balad Air Base in Iraq to the Brooke Army Medical Center in San Antonio.
. . .
Above England at 26,000 feet, Capt. Charles “Spanky” Gilliam met a tanker successfully, taking on 110,000 pounds of fuel. With burns to 20 percent of his body, Ping could not survive two pressurization schedules. If the fueling would have failed, so would the mission.
So they made it, but it was a near thing. A longer range plane like a 777 or possibly A330 could have made the flight without having to worry about refuelling and also would have made it faster
C-17: 7500 miles at 518mph = 14.48 hours
A330: 7500 miles at 534mph = 14.04 hours
777: 7500 miles at 564mph = 13.3 hours
and that doesn’t account for the extra time taken while refuelling
The US relies on CRAF and other civil contractors for most of its pallet capacity. It’s only ‘real’ pallet hauler is the KC-10, which is heavily tasked and generally unavailable for such duties. Thus C-17s and C-5s are misused for this role.
also:
C-17: 48 litters
KC-30: 120 litters
Currently the best hope for this is KC-X, which will provide a large number of suitable pallet transports, but this keeps getting delayed and tankers are often tasked elsewhere, so it may be prudent for the USAF to procure some dedicated pallet haulers like 777s or 747s in addition to KC-X
CRAF is good, but civilian pilots and airplanes without self-defense systems are limited as to where they can/will go
3. Strategic Transport
The heart of strategic transport is moving massive quantities long distances.
Some of the critical points to this have been covered previously:
a) capacity: the C-17 is simply too small to be considered a strategic transport, it takes too many flights to transfer stuff. It’s like trying to put out a fire with a bucket brigade when you could have a fire hose.
b) range: purely unacceptable. For any number of possible deployments, C-17s will hog all available air-refuelling assets and then some
Now I want to cover a different aspect of strategic transport:
c) outsized loads
i) loads that a C-5 can handle that a C-17 can’t, such as
– M104 mobile scissors bridge
– MK V SOC boat
– special one-off situations like a C-130 fuselage (http://www.ngb.army.mil/news/archives/2008/09/091508-Stratton_ANGB.aspx)
http://www.accessmylibrary.com/coms2/summary_0286-5908419_ITM
“The C-5 [Air Force transport plane] is vital for our emergency response capability; it’s the only aircraft we can fly [these boats] in,” Lt. j.g. Bob Pudney, officer in charge of the Mk V boat displayed here May 18, told Defense Daily in an interview “From the time they are ordered in, the Mk Vs must be operational within 24 hours. The replacement for the Mk V will have to be smaller for the C-17 [transport]. Right now, if the C-5 goes away, we would lose our rapid deployment capability.
They’ve already said that they will have to design the next boat smaller so it will fit in the C-17. We are compromising our capabilities because of the C-17’s limitations. Unacceptable
ii) loads that even the C-5 can’t handle
– V-22 osprey
– GE90 engines for the 777s they’re going to buy 😉
– all sorts of stuff
iii) stuff that will fit in the C-17 but requires extensive teardown
you can fit a chinook in a C-17, but it requires over a day to put it back together, obviously not very practical or desirable
similar story with the CH-53 (and presumably the upcoming CH-53K), you can cram it in there, but it’s painful
The C-17 can only carry 1 abram at a time, a C-5 theoretically could carry 2 but has load restrictions and center-of-gravity issues and so is limited to 1 also.
Here is where EAGL gleams bright in the future. Hopefully a true strategic airlifter that puts the An-124 to shame. Something that can carry 3 abrams, something that could carry a couple chinooks without extensive teardown, something that could even carry an osprey. And could do all this at super-long ranges without refuelling
Summary:
The C-17 is a too-small, short-ranged, gas-pig
The USAF should build up it’s fleet with the right tools for the job instead of trying to shoehorn all tasks into a compromised one-size-fits-none airframe
tactical: continue C-130J and C-27J and investigate possible C-130XL/A400M
pallet/aeromedical: get KC-X already! and possibly supplement with commercial freighters like 777 or 747 (with appropriate militarization and self-defense suites)
strategic: get moving with EAGL and finally have a true successor to the C-5 that can move massive amounts of anything around the globe
In defense of the C-17:
This shouldn’t be taken as an attack on the C-17, but rather of trying to use the C-17 to meet all our airlift needs.
The C-17 is reliable and flexible, and there is much to be said for that.
Certainly there are situations where it’s unique capabilities are required. But the point is that those are niche requirements and you don’t build your entire fleet around a niche capability. We have more than enough of them to fill that niche.
You hear much moaning about how we need to build more C-17s because we’re burning them out with heavy usage.
The solution isn’t to build more C-17s, it’s to assemble the right mixture of capabilities to take the load off the C-17s
Shipments that might have involved 3 C-17s and multiple tankers could conceivable be done with a single EAGL with no refuelling support
Once we have enough aircraft to fulfill the additional duties it has taken on, the C-17 can be relegated back to its proper niche. With the large number of airframes and the hugely reduced demand for them, they should expect a long, fruitful life in USAF service
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February 22, 2009 at 5:02 pm