New Aerial Refueling Tanker KC-X

Recently there has been increasing concern about the age of the US aerial refueling tanker fleet and its potential impact on the military services’ ability to meet operational requirements. If you want to know where there will be the next war then you should just “follow the tankers.” Now, a lot of people talk about a possible attach on Iran. Question: are the tankers in the periphery already?

The USAF intends to replace its aging refueling tankers and hence want to but for the moment 179 new one. This post is about those tankers, the old ones and the alternatives.

Fuel use imposes large logistical burdens. Therefore it would not be farfetched to argue that logistic aspect is the weakest link of a country’s armed forces, especially air force aircrafts, in war. It is aerial refueling tankers that extend the range and time of combat and non-combat aircraft. By transferring fuel they carry to receivers (fighters, bombers, cargo planes and other aircraft) they allow receivers to refuel without landing.

In order to get the fighters, bombers and reconnaissance missions to their designated mission areas and then to remain there in a strike or an on-call position, they must hook up with a tanker and refuel.

A bit history

The U.S. Air Force began developing aerial refueling tankers in the 1940s to support heavy bombers. By June 1948, the Air Force had its first two tanker units. The first combat refuelings took place during the Korean War. Beginning with the Vietnam War refueling tankers became an integral part of air campaigns.

In the first Gulf war of 1991 more than 300 tankers were deployed. In 1999, during the Kosovo crisis, B-2 bombers refueled by tankers flew roundtrip from the U.S. to Yugoslavia to open the air campaign.


Note: A Turkish Air Force KC-135 . Source: Turkish Air Force Command

During Operation Enduring Freedom, flying into Afghanistan required a full network of aerial refueling to support long missions by everything from Navy fighters[1] to B-2 bombers to C-17s dropping humanitarian relief supplies. Tankers operated from locations such as Karshi Kanabad, in Uzbekistan, and Manas Air Base in Kyrgyzstan.

In the early months of Operation Iraqi Freedom, 149 KC-135s and 33 KC-10s conducted 6,193 sorties in support of the joint force, off-loading 376,391,000 lbs. of fuel to U.S. and allied planes.[2] In 2005, tankers in theater flew 12,071 sorties and offloaded 755 million lbs. of fuel, just for Central Command.

Current Fleet and Age

While numerous US military aircraft provide refueling services, the bulk of aerial refueling capability lies in USAF fleet of KC-135 Stratotanker (based on Boeing 707) and KC-10 Extenders (based on McDonnell Douglas DC-10).[3]

There are two basic versions of KC-135 -- KC-135E and KC-135R (re-fitted with modern engines and other upgrades such as refueling capacity). Active forces have only R models. The current USAF tanker fleet consists of 531 KC-135 (114 KC-135E and 417 KC-135R) and 59 KC-1.[4]

But Air Force magazine gives a different picture. Below is the tanker inventory as of Sept 30, 2005

Data Source: Air Force Magazine, May 2006.

The KC-10[5] aircraft are relatively young, averaging about 21 years in age, whereas average age of KC-135s is 45 years. They both are expected to remain in active inventory until 2040. The last KC-135 was delivered in 1965.

It is therefore no surprise that General T. Michael Moseley, Chief of Staff of the Air Force, announced in October 2006 that KC-X tanker is the Air Force's new number one procurement priority.[6]

On the other hand a GAO report in 2003 stated that “The Air Force projects that the KC-135 aircraft have between 36,000 and 39,000 lifetime flying hours; according to the Air Force, only a few KC-135s are projected to reach these limits before 2040, although at that time some of the aircraft would be close to 80 years old.”[7] According to the Air Force, only a few KC-135s would reach these limits before 2040, but at that time some of the aircraft would be about 80 years old. Flying hours for the KC-135s averaged about 300 hours per year between 1995 and September 2001. Since then, utilization is averaging about 435 hours per year.

Michael W. Wynne, Secretary of the Air Force quoting General Buzz Moseley said “The pilot that has yet to fly the KC-135, the last KC-135, has not been born yet….In fact, his mother has not been born yet.”[8]

Some technical details

Dr. Rebecca Grant and Dr. Loren Thompson of Lexington Institute[9] give an excellent account of technical details. Let me give some facts from their report, supported by sources.

The KC-135 typically carries 180,000 lbs aloft. In addition it can carry 35,000 lbs[10] of cargo. The larger KC-10 holds 327,000 lbs.[11] In addition it can carry up to 75 troops and 170,000 lbs of cargo. Note that KC-10 can be refueled in the air.

Current tankers seldom offload all their fuel during air operations. The amount of fuel available to receivers depends on the distance the tanker flies, the burn-rate efficiency of its engines, weather condition and speed of the tanker.

During Operation Desert Storm, the average tanker offload (for all types, including some coalition tankers) was 47,500 lbs. per sortie. Eight years later in Operation Allied Force, the air campaign during the Kosovo crisis, the average was 48,700 lbs. per sortie. Offload rates averaged 75,400 lbs. per sortie in Operation Enduring Freedom from 2001 to early 2002 (due to the long distances that receivers had to fly). Major combat operations in Iraq during the spring of 2003 saw averages of 60,800 lbs. per sortie. Stability operations in Iraq and Afghanistan saw fewer strike sorties, but similar offloads of 62,400 lbs. per sortie in 2005. During a round of Iraqi elections in January 2005, the offload average peaked at 89,000 lbs. on one particular day as extra sorties were flown for election security.

Fuel transfer rate from a tanker to today’s existing aircraft is 2,000 lbs. per minute. An average F-16 receives 6,000 lbs. of fuel. When we add the extra 5 minutes for positioning for the refueling, total time needed for one aircraft refueling is 8 minutes.

Replacement efforts

Modernizing or replacing the aging tankers has been a concern for more than a decade now. But serious discussions have started in recent years.

I will skip in this post the story....

And in 2006 things have started to move again. According to a New York Times article on October 13, 2006 (Air Force seeks $13 billion to start replacing tankers) USAF is seeking $13 billion over the next five years to replace their aging fleet of aerial refueling aircraft.

It is considered to be one of the biggest single buy USAF acquisitions since WWII. The USAF intends to procure the first order of 179 new flying gas stations, worth up to $20 billion. Total procurement cost is estimated at $200 billion (some say $100 billion) over a 20-year period.[18] Currently there are two competitors for bidding proposals – Airbus and Boing.

What type of a new tanker ?

There were plans for more than a decade for the design and specifications for a new aerial tanker (called KC-X). There are numerous factors such as size, speed, range, payload and price that must be considered. But apparently the USAF does not know exactly it wants.

Some favor medium size tanker mainly because a) use of multiple medium size (such as KC-135) reduces the total fueling time if more aircrafts are needed to be refueled, b) multiple large size aircrafts are not easy to accommodate at a base. Note that several factors[19] limit the number of tankers that can be accommodated at a base.

Many argue that it would be useful to employ empty space on future tankers for carrying cargo[20] as well as passenger so that the air fleet is as flexible and versatile as possible. To them capability assessment is a must and focus should be on recapitalization of capabilities, not replacing an old one with a new one.

According to Leon La Porte,[21] former commander in Chief of UN Forces in Korea, “The primary mission of the KC-X is to provide worldwide, day/night, adverse weather aerial refueling. Secondary missions include airlift, communications gateway and aeromedical evacuation.”

Besides those, there appear to be four general options for recapitalizing the aerial refueling capability of the KC-135 fleet: re-engine and modernize the current fleet, purchase one or more models of new commercial aircraft and convert them into a military tanker, purchase and convert used commercial aircraft into tankers, and lease aerial refueling services from the private sector.[22]

Bidder’s Dog Fight

While the Pentagon is moving to pick up the supplier of its next generation aerial refueling tanker, the two candidates (Boeing Co. and rival consortium Northrop Grumman and Airbus parent European Aeronautic Defense & Space Co.) already have started a dog fight for bidding. Northrop is offering the Airbus A330-200 based KC-30 as a refueling tanker, and Boing is offering KC-767, a high performance version of the Boing 767-200ER jetliner equipped for fully integrated tanker operations. Boing has produced close to 2,000 tankers in its history and has already sold nine KC-767 to foreign militaries – four to Italy and five to Japan, which will be delivered in the coming years.

According to Northrop Grumman's website, their KC-30 Advanced Multi-role Tanker Transport provides 27 percent more fuel than the KC-135R, transports 1.8 times more bulk pallets than the C-17, and carries approximately 280 passengers or approximately 120 litters in an aeromedical configuration. The company is pushing for a capabilities-based contest giving greater weight to cargo and passenger capacity, which could eventually force Boeing into offering an even larger Boing 777 jetliner based tanker.

Boeing’s KC-767 can carry 19 more cargo pallets, and Northrop’s KC-30 can carry 32 more cargo pallets than KC-135, depends on how far they are flying and how much fuel they are intended to deliver.

Apparently the main issue for USAF is the number it can buy. A330 costs about $160 million per plane vs. $120 million for the 767. That is why Northrop says that if the capabilities-to-cost evaluation metrics aren't included in the final RFP, the company feels the KC-30 will be noncompetitive and we will no-bid. There are rumors that Northrop will withdraw, leaving Boeing as the only bidder.[23]

The USAF is expected to release its final-final KC-X request for proposals (RFP) on January 30, 2007. Northrop Grumman warns that, if the final RFP does not differ significantly from the draft released in December, it will not bid for the 179-aircraft contract.

According to newspapers[24] Air Force Secretary Michael Wynne said "We want to buy a tanker. We do not want to buy a cargo airplane that tanks. We also do not want to buy a passenger airplane that tanks….Its primary mission is going to be a tanker. The fact that it can carry cargo or passengers is a benefit, but it is not the primary reason for the procurement." He is also reported (by INSIDER news service of insidedefense.com) saying "I do not see any reason to change the evaluation criteria, and I have not been convinced that there is a reason to change the evaluation criteria," during a January 18 interview at the Pentagon.

By the way, in the world market Airbus was ahead of Boing since 2000. But now things changed. Boing regained the lead and sold more airplanes than Airbus. While Boing was increasing its power, Airbus was declining. Production delays of A380, its new A350 is being redesigned after heavy criticism, and changing four bosses in two years give a headache to Airbus. But Boing had its own sex scandals and corruptions that cost the jobs of three top executives.

To me capabilities don’t say everything. What is more important is the need. The USAF needs tankers. Hence they should get tankers. More fuel carrying capacity, extra more people and cargo carrying capacity do not mean much since in their entire lifetime KC-135’s on average neither emptied all the fuel they carried nor they were really needed to carry cargo. I do not see any reason why it should change in the future. If the USAF buys Airbus version only then they should think twice on which overseas bases they can put them.

Or else the USAF could buy both planes, some Airbus and some Boing. Why there must be only one type plane is beyond my understanding. I am not interested in all these bidding part anyway. But it seems that “buy American” sentiment is gaining more ground. By the way, the only connection between me and KC-135 is my age -- the youngest KC-135 is at my age.





Tags: US Military, Aerial Refueling Tankers, KC-135, KC-X, US Air Force, KC-10