Posted on 06/23/2015 4:57:10 AM PDT by sukhoi-30mki
Fuel is the ever-present specter that looms over every pilot. It’s great when you have enough of it, and terrifying when you don’t. This is especially true for notoriously fuel hungry tactical fighters. Conformal Fuel Tanks (CFTs) have become an increasingly popular way to add range to existing fighter designs, such as the F-16, without making a large impact on the jet’s speed and agility. Many overseas operators utilize CFTs on block 50/52 and later Vipers, but why don’t America’s late model F-16s have a similar luxury?
Conformal Fuel Tanks are not just the domain of late model F-16s, the F-15 has long benefitted from its own CFTs, and CFTs are in the works for the Gripen, Super Hornet, Rafale, Ching Kuo and Eurofighter. Advanced versions of the MiG-29 have also been fitted with a dorsal conformal fuel tank and China’s J-10 has a CFT option in development.
The F-16’s CFTs weigh just 900 pounds per set and can carry 450 gallons, about 3,050 pounds of jet fuel. Considering that an F-16 holds about 7,000 pounds of internal fuel, just the CFTs alone offer a 43.5 percent fuel increase with little additional drag. Also, they don’t take up precious stores stations under the jet’s wings or belly like traditional drop tanks.
Pilots have been fairly explicit about how little the F-16’s CFT’s impact the F-16’s notoriously spirited performance. Maj. Timothy McDonald, U.S. Air Force project pilot for F-16 CFT testing at Eglin AFB described the bolt-on addition like this:
“The CFTs have very little adverse effect on the F-16’s renowned performance. A set of CFTs carries 50 percent more fuel than the centerline external fuel tank, but has only 12 percent of the drag. The aircraft retains its full 9-g capability and flight envelope with the CFTs installed. The drag impact is very small, less than one percent in combat configuration at cruise conditions.” Stephen Barter, Lockheed’s CFT project pilot at the time of their developed also stated:
“The flying qualities of the F-16 with CFTs are essentially unchanged when compared to a non-CFT equipped airplane. For most combat flight conditions, it’s as if the CFTs are not even there. The surest way for me to tell if CFTs are installed is to look over my shoulder.”
F-16 CFTs are designed for the jet’s full flight envelope, up to 9 g’s, maximum angle of attack, sideslip and maximum roll rate and they have almost no impact on maneuverability or speed below mach one, where fighters spend the vast majority of their time. Even above mach one, they have less performance impact and carry more fuel then a centerline drop tank.
While Israel, Turkey, Poland, Greece, Morocco, Pakistan, Oman, Singapore and the UAE all actively use CFTs on their F-16 fleets, the U.S. has bypassed the option all together.
Seeing as USAF F-16s never fly in combat without multiple external fuel tanks, which greatly hampers the jet’s performance, aren’t CFT’s a no-brainer? It would seem so, but the USAF uses some seemingly backward logic when it comes to not procuring them for their Block 50/52 F-16 fleet, which is the top-of-the-line, youngest F-16 sub-fleet in the USAF’s inventory.
From what I have gathered over the years on the topic via talking to pilots directly and seeing mentions of the decision in publications from time to time, the USAF justifies not procuring CFTs because it already has so many tanker aircraft. Additionally, in a major air battle they don’t need the extra weapons stations freed up by the inclusion of CFTs as a great advantage because they can simply assign more F-16s to target set. For longer-range strike missions they can use the F-15E or even a bomber.
These justifications, and the fact that although the CFTs don’t inhibit daily line maintenance and inspections when fitted to the aircraft they do take a couple hours to remove for heavy duty servicing and phase inspections, seems to be entire reasoning behind not equipping American late model Vipers with CFTs.
Now let’s take a closer look at this rationale. It is true that the U.S. has a dizzying amount of tanker aircraft, about 450 in total, with 59 being KC-10 Extenders and the rest being KC-135R Stratotankers. These aircraft can also be used for cargo missions but mainly they provide refueling for thirsty U.S. and allied military aircraft. Meanwhile, the F-16 still represents the backbone of the USAF’s tactical air combat capability, with over 900 units still in service even after many squadrons have been shuttered due to budgetary cuts.
Over 250 of these aircraft are Block 50/52 F-16CJs that were delivered optimized for CFTs. In other words, around 30 percent of the USAF most advanced and youngest F-16s could easily be fitted with CFTs, many of which have the challenging “Wild Weasel” Suppression of Enemy Air Defense/Destruction of Enemy Air Defenses (SEAD/DEAD) mission. This demanding mission is a critical support capability that is needed to ensure the safety of both short-ranged and long-ranged aircraft against an enemy with even a rudimentary air defense system.
The F-16, with its limited range and “work in progress” Harm Targeting System (HTS), has never been ideally suited for this mission, only really coming into its own in it after key avionics and weapons upgrades over the last decade or so. The addition of another 40 percent or so of internal fuel would help make the jet the best Wild Weasel it could possibly be, and give it the legs it needs to work anti-aircraft systems over while strike and counter-air aircraft accomplish their missions in enemy airspace.
Adding close to 50 percent internal fuel to 25 percent of the USAF’s existing F-16 fleet offers a slew of benefits, both tactically and strategically. First off, greatly enhanced loiter time and range. This will allow these F-16s to not be as closely tethered to aerial tankers as they are today, having to depart roughly every hour to refuel while over the combat area, which greatly complicates planning and can leave a hole over a key area of the battlefield. This is especially when executing critical close air support (CAS) and Wild Weasel missions.
On medium and short range missions, CFTs mean more maneuverability, less drag penalty and more weapons available per aircraft when compared to flying an F-16 with cumbersome under-wing tanks. On long-range missions, where underwing drop tanks are paired with CFTs, it means enhanced range and on station time.
As for the idea that the USAF’s massive tanker force makes CFTs less relevant, this seems like a very near sighted look at the enhanced capabilities CFTs offer, and it is a somewhat archaic look at the current realities of air combat.
America’s tanker fleet will erode in numbers over time. The KC-135s, many of which are over 50 years old, cannot fly forever, and finding funding for replacing them on a one-to-one basis with the KC-46 will be all but impossible. Even the heavy hauling KC-10 Extenders have been under the budget axe as of late, simply due to their cost of operation.
Keep in mind that this comes as the USAF looks to procure over 1700 F-35As, each carrying over two and a half times the internal fuel as their F-16 counterparts. This would not be an issue if the new stealthy jets featured over double the range or combat radius, but they don’t. As such, they will be highly dependent on tanker gas to accomplish their mission just as their F-16 predecessors, only they are much more thirsty. This will put greater pressure on a shrinking tanker fleet during future conflicts.
Then you have the Pentagon’s supposed “pivot towards the Pacific,” where long distances and the realities of limited logistics and austere basing and support infrastructure are the greatest challenges to overcome. Allowing America’s Block 50/52 F-16C/Ds to operate more independently of tankers, over greater ranges, is a logical move if this strategy is going to be taken seriously.
Then there is the tanker vulnerability issue, as they are large targets incapable of defending themselves, and tasked with operating within a few hundred miles of their short-legged fighter dependents. During a war against an enemy with anti-access and area-denial capabilities, this could mean long ‘tanker bridges’ shuffling fighters from far away bases to the front lines. It also means that the tankers themselves will be far-forward deployed. As such, they will be vulnerable to enemy attack, especially during swarming enemy operations, or those where advanced low-observable enemy aircraft are being used. Thus, the farther these tankers can be pushed back by increasing our combat aircraft’s organic range the safer they will be during such a conflict conflict.
Also keep in mind that over the vast reaches of the Pacific, during even a limited near peer-state conflict, if the enemy kills the tanker, they may also have killed all the fighters dependent on that tanker as they would have to divert to bases vulnerable to enemy attack or run out of fuel and ditch in the ocean.
Finally, you have cost. Tanker gas costs anywhere from $25-$35 per gallon (some claim it is closer to $50) when you factor in the costs associated with aerial refueling. This is in comparison to about $5 to $6 when an aircraft is fueled on the ground. During sustained low-intensity warfare operations or during training, relying more on ground-based fuel than on tankers is a much more economical way to go about the fighter business. It will also offer more time per sortie during training when aerial refueling assets are not used. This means less aircraft “turns” and much greater efficiency when getting pilots their required training hours. Less sorties, but longer ones, is also easier on the hardware.
The best part about the CFTs is that they are removable. For certain operations, if they are deemed unnecessary, the aircraft can be left stripped of them, and for other missions they can be fitted. For instance, over Afghanistan, where persistence during CAS missions was key and there was no air-to-air or advanced surface-to-air threat, hauling some 40 percent more gas while being able to carry more weapons seems like a pretty logical advantage. Yet even during combat operations, where there is a robust surface-to-air and air-to-air thrust, any slight hinderance the CFTs cause to agility, which apparently is almost nothing, is overcome by being able to stay in the fight longer at higher thrust settings.
Also, we live in time of high-off bore-sight air-to-air missiles and towed decoys, where raw agility is becoming less and less of advantage in combat. Instead, range, persistence and the ability to get the maximum out of the aircraft’s powerplant when needed, for as long as needed, are what’s paramount.
The claim that the USAF can just stack more F-16s to take out a set amount of targets and fulfill a set number of patrols seems incredibly reckless. Just because the assets are available it does not mean their use is necessary. Why put more crews and material at risk than you absolutely have to during a time of war? Especially considering that losing just one F-16 will end up in putting so many more personnel at risk during a combat search and rescue operation.
The fact of the matter is that America’s youngest F-16s will continue to serve for decades to come, most likely taking on many of the ‘bread and butter’ roles that using a $100M+ stealth fighter makes absolutely no sense for.
With all this in mind isn’t it totally reasonable to ease up a bit on America’s fighter force tanker gas addiction and give F-16C/D Block 50/52 crews more persistence and range via the addition of CFTs? Especially considering the capability is proven, bolt on in nature, has little adverse consequences when it comes to agility and is already available off the shelf?
Logic would say yes, but the USAF somehow says no.
Follow the money. There is the answer. As for not being plumbed, that’s not an issue on new machines.
But the simple answer is someone didn’t bet the payola.
Would these CFT give Israeli F-16s the range to reach Iran, and back?
Loved that post. Learned a lot.
Probably, via direct route, almost all over hostile territory. It is believed the Israelis have such configurations.
But they won’t have to.
Saudi will will refuel them and allow passage....
Saudis are not of one accord. Some Saudis may authorize it while others might sabotage it. And that leaves out the question of whether the US would allow it.
Oh, the only Saudi’s that matter, the Sauds, will do it.
Anything to stop Iran’s getting a nuke.
Anything.
Now we know how the Israeli’s will reach Iranian targets.
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