A next-generation US Air Force tanker. Which off-the-shelf aircraft would you select?

Question

The KC-135 entered the Air Force inventory in the 1950's. The KC-10, an adaptation of the McDonnell Douglas DC-10 airliner, joined the inventory in the late 1970's.

Both are aging. What should be the replacement airframe?

One current proposal is to modify the Boeing 767 airliner. I don't know if it has ever been proposed formally, but it would seem another good candidate could be the C-17 Globemaster III airlifter--possibly as a convertable tanker/airlifter.

What would you suggest? Modified 747s? Maybe a 777 mod? Even a 787 mod? How about a bus--an Airbus, that is? Or maybe a redesigned Lockheed C-5?

Or should it be an all-new airframe? With the newest Air Force tanker now nearly 30 years old, it is safe to say this tanker will be around for a while. What should it be?

Save the free world. Suggest the next major gas passer.

The 141 is probably too old a technology to bring back and the existing airframes are very high time. I like the airplane, but it's probably best relegated to history as a machine that paid for itself many times over.

Again, how about the C-17? It's almost as big as a KC-10, and probably faster. On the ground it takes about the same parking space as a 141.

The old C-97 had a loading ramp in the rear in the cargo version. When Boeing adapted the aircraft to a tanker role that became the location for the flying boom module which became the standard system for passing a lot of fuel in a hurry.

In adapting the C-17 to a KC-17 role I would envision either locating the refueling boom to the sides, or making it a removable module replacing the cargo doors. If a practical flying boom module could be placed under each wing, this tanker might be able to refuel two aircraft at a time, something neither the KC-10 or KC-135 can do.

Probe and drogue fueling systems are a bit simpler, and three such hoses were used on the old KB-50s that served with TAC.

Might note that several of our current crop of military aircraft are foreign. The Air Force's T-6 Texan II is an adaptation of an Italian design. The Navy is using a trainer that is a British design.

If an Airbus design were to be adopted there would have to be a way to either buy the airframes and add the refueling packages or to manufacture the entire tanker under license.

Incidentally, I am not advocating any design, including the Airbus or Boeing designs. Best option might be to develop an entirely new aircraft. This would be very expensive and the cost might well be defrayed by developing an airliner version for worldwide sale.

The modified KC-135s are also fully adapted to using probe and drogue refueling systems.

USAF tankers can refuel Navy or Marine and even some allied military aircraft. The flying boom is preferred by the USAF because it offers a higher speed fuel transfer than the simpler probe and drogue. A few Air Force fighters were equipped for probe and drogue, and the F-105 was built to receive fuel both by the flying boom and probe and drogue methods.

Here's a novel idea.

Why not build a two-fuselage aircraft, each of which would have a flying boom in the tail section?

Each fuselage would be structurally a wide-body transport such as a 767 but they would be joined by a common center wing section and a common center horizontal stabilizer.

It would be powered by 3-4 large turbofan engines of the type used to power the 777.

For a similar, but much smaller, design, see the North American P-82 Twin Mustang. Each fuselage would have space for both fuel and cargo, and the center wing would offer additional tankage.

Two drawbacks I can think of--weight and balance would be a nightmare in an aircraft of this type. And, as wide as it would be, it would be limited to a relatively small number of airfields.

But it could meet the specifications and then some.

For outboard flying boom stations--how about virtual reality goggles for the boom operators? Maybe even a semi-robotic system?

The KC-10 was an outgrowth of a design competition for a super tanker to replace the KC-135 in both the strategic and mobility support tanker roles. Unfortunately it did not offer enough of the right characteristics of a strategic tanker to perform acceptably in that role. The result is that we now have KC-135s assigned to both tanker roles and the KC-10 supporting mobility.

Should the new Air Force tanker be able to perform both strategic and mobility tanker roles?

Answer 1

I concur about the KC-135 being overdue for retirement--same age and fatigue issues as the B-52. The McDonnellDouglas KC-10 is still in low-rate production after a fashion as the Boeing KC-10 Charlie, to expand Air Mobility Command's tanker squadrons.

The Boeing 747 is already used for some specialized missions by the Air Force, so I don't see anything to contraindicate development of a KC-29 Echo from the 747SP (SAM 29000 and 30000 are VC-29 Deltas, based on the 747-200). The Boeing 767, not currently in Air Force service, is a reasonable candidate for both flying-infirmary and tanker missions. Both the C-29 and the 767 should be simple enough to adapt for the tanker mission, as the fuel boom and its operator station could be located where structure permits.

One trick in developing a KC-17 will be locating the fuel boom, as it must not interfere with the loading ramp. One type I do not see replacing anytime soon is the Lockheed KC-130, as it can safely fly slow enough to refuel helicopters after herself topping off from a KC-10 or successor jet tanker/transport.

Addendum: At this time, for safety issues, I don't see a two-boom KC-17, as the operator stations would be VERY widely separated from the boom mechanisms in the wing; a camera on the housing portion of the boom has a very limited FOV. All USAF tankers can use the Flight Refuelling Ltd. hose-and-drogue hardware developed in Britain and already servicewide standard for Navy and Marine Corps aircraft both fixed and rotary wing--the Marines use this system off both wings of their KC-130's, and the Air Force already flies it on the KC-10 to support USN/USMC tactical jets in addition to the aforementioned KC-130.

Addendum 2: Excellent point, sir--developing an airliner/airfreighter from the tanker may very well be the best route; the Boeing 707-100 was an outgrowth of the Air Force KC-135 program, which used the preproduction 367-80 as its baseline. The KC-29 would definitely have the range needed for a strategic tanker, requiring (as I see it) only a major alteration of the aft fuselage to allow flush (recessed?) retraction of the boom (as a hedge against damage during a max-perf takeoff as Boeing used during the 747-100 trials). With Boeing and Airbus both working up new 400-passenger heavies, now would be a perfect time for the Air Force to begin concept formulation studies for what I would call KCX, viz., Tanker/Cargo Experimental, with its end result being a new optimized strategic/tactical tanker for Air Mobility Command. Flight Refuelling Ltd. would be along for the ride, as KCX should carry up to four feedhoses, with drogues, in addition to the Boeing-patented fuel boom.

Answer 2

The Boeing 767 seems like a good candidate to replace the older DC-10's and Boeing 707's as an aerial refueling platform, as does the Boeing 777. Both the Lockheed C5 and the Boeing 747 may be getting a little too old to fill the role. My father was a flight engineer on refueling aircraft when he was in the Army Air Force / Air Force he flew on KB-29's KC-97's, and the KC-135.

Answer 3

If we can spend millions of dollars to build new fighters. Why can't we put out a contract to build a new flying gas station. Which will fill our needs for the next 40 years. We need an aircraft that is capable of refueling more then one plane at a time, like from the wings, two at a time. The technology is available.
Lets put it out there and see who can come up with the best design, be it Boeing or Airbus or whoever. Be it based on current design or a new plane. Put out the specs and see what they can come up with for what we need.

Answer 4

I would think a 767 or 777 tanker would best suit the mission. Under no conditions would I buy Airbus, military aircraft should be built in America not by a foriegn company.

Answer 5

A modified C-141 might work.
The C-130? too low and slow.

Answer 6

if it aint broke dont fix it look at the c-130 we are still finding uses for it like turning them into AC-130 SPECTRE gunships