The Mystery of the Dropped Fuel Tanks

I had vowed to give up blogging on Middle Eastern affairs.

However, an e-mail from a reader concerning the Israeli raid on a purported North-Korea-linked military facility in Syria enticed me to wander off the Asian affairs res once again.

FYI, the combat radius of an F-15 in deep strike mode is 1800km
The distance to the Syrian target is ~ 700 km.

No need for drop tanks........

Hmmm. Too interesting to pass up.

The Internet is a treasure trove for armchair commanders and aviation and weapons enthusiasts. Industrious googling yielded the following information:

During the raid, some Israeli aircraft jettisoned two external fuel tanks up by the Turkish border.

The tanks were from an F-15I fighter bomber , called the “Ra’am” or “Thunder”, itself the Israeli variant of the F-15E Strike Eagle.

In agreement with my correspondent, the Observer states the Ra’am is:

...the newest generation of Israeli long-range bomber, which has a combat range of over 2,000km when equipped with the drop tanks.

But I think the Observer (and perhaps *gasp* a loyal reader) got it wrong. Either they confused cruising range with combat range, or confused the current F15I with its previous incarnations (for instance the F15C does have a combat radius of 2000 km).

The F-15E is a completely different animal from previous F-15s, which were sleek interceptors, designed “without a pound for the ground” i.e. no air to ground armament, for those days of air-to-air combat with the parfait knights of the Soviet bloc.

The F-15E is a big, fat hog of a plane, sometimes nicknamed the Flying Tennis Court, or Rodan for its resemblance to the ungainly but murderous superpterodactyl featured in the Godzilla movies.

It’s meant to carry big bombs and missiles to blow up stuff on the ground and the people standing in it or next to it, and fight its way out if necessary.

So it’s got bigger engines and less range than previous F15s.

According to the data I dug up, the F-15E has a combat radius—the distance it can be expected to fly for a mission assuming high speed, fuel-consuming maneuvers--of 790 miles (see here and here ).


To achieve this radius, it needs its internal fuel plus external fuel.

Internal fuel capacity is 5,952 kg.

External fuel consists of two components:

Conforming fuel tanks or CFTs with a total capacity of 4500 kg. They are integral parts of the plane—one report I read said the plane isn’t really designed to fly without them—and can’t be jettisoned.

Then there’s another 5500 kg in conventional external fuel tanks—the kind that were dropped during the mission.

With a fistful of caveats, the combat radius for an F-15I without the external fuel tanks would be around 500+ miles.

Distance from the Hatzerim airbase (home of the F-15I-equipped 69th Squadron) near Beersheba to Dayr az Zawr: 420 miles.

So you might think that the conventional external fuel tanks weren’t needed for this particular mission, and the only reason to carry them was for road-testing prior to some Iran-related hanky-panky.

Maybe yes, maybe no.

If the Israelis really did bomb Dayr az Zawr, it’s unclear why they went barnstorming up to the Turkish border a hundred miles away.

But they certainly did go, and to fly that kind of mission including a flyby of the Turkish border, I think they would need the external fuel tanks.

Maybe the Turkey excursion was to test some fancy new electronic countermeasures equipment mounted on another plane, called “Suter”, to disrupt Russian air defense hardware recently supplied to Syria—and Iran, for Israel’s benefit and our own.

Aviation Week put out the story courtesy of “U.S. officials”:

A Kuwaiti newspaper wrote that "Russian experts are studying why the two state-of-the art Russian-built radar systems in Syria did not detect the Israeli jets entering Syrian territory. Iran reportedly has asked the same question, since it is buying the same systems and might have paid for the Syrian acquisitions."


We got a certain amount of military chest-thumping about how cool this new gear is, but these planes only jettison their fuel tanks if they’ve been engaged and need extra speed and mobility, which leads one to believe it couldn’t have worked too great.

As to Israeli insistence that they’ll take out Iran if we can’t get off our collective rears, I found this analysis interesting and persuasive.

It argues that the Israeli air force simply doesn’t have the horses to haul the armament needed to make a terminal dent in the hardened and dispersed Iranian facilities on a 1200-mile mission—remember, more fuel means fewer weapons carried--unless the U.S. either assists in the refueling of the Israeli planes or allows them to stage the assault U.S. from bases in Iraq.

And maybe not even then.

Bottom line:

Theoretically, the Israelis could do this, but at great risk of failure. If they decide to attack Natanz, they will have to inflict sufficient damage the first time - they probably will not be able to mount follow-on strikes at other facilities.

When all the analyses are done, there is only one military capable of the sustained widespread air operations required to eliminate Iran's nuclear weapons research program - the United States.

So it looks like the Israelis could start something—but it would be up to Uncle Sam to finish the job.

I take this as support for my thesis that a key data point for Israel from the Syria raid was the nature of the U.S. support it did—or did not—elicit, and what that would mean for Israel if it conducted a dramatic but less than conclusive raid on Natanz with the hope that the U.S. could be dragged into the campaign.

So: War with Iran—it’s up to us. Don’t know whether that’s reassuring or disturbing.