Lockheed Martin has been handed another $134 million contract to develop a "partner version" of the JSF "that meets U.S. National Disclosure Policy, but remains common to the U.S. Air System, where possible." That's on top of $603 million awarded for the same basic job four years ago.

That's pretty close to the billion dollars that USAF Lt.Gen. Jeffrey Kohler, head of the Defense Security Cooperation Agency, said would be needed to create a sanitized F-22 for Japan.

The Delta SDD program mentioned in the contract documents is an interesting beast. Look at papers from the Netherlands from 2004 - when opposition politicians asked after the 2003 contract whether it meant that the Netherlands were getting a less-stealthy JSF. They stress that the Delta SDD covers things like nationally required features (for instance, Norway wants a braking parachute) and nationally specific weapons - if someone wants IRIS-T, for example.

But that clashes with the bald statement in the Pentagon contracts that the $737 million program is about security and protecting US technology, by delivering air vehicles that are different from US air vehicles - "as common as possible". Also, features such as nationally required weapons wouldn't be covered in SDD, which has a defined set of weapons to be cleared for the Block 3 configuration - the endpoint of SDD.

Does this mean that there are two or more versions of the JSF, with differing uses of sensitive technology - meaning, in most people's eyes, stealth? It's certainly possible, because key LO features - such as the edges of the wing and chine and surface coatings - are built in secure facilities and added after major assembly - as can be seen in an unpainted F-22.

The decision on whether to release stealth technology is also not up to the JSF program office, but to a high-level group called the LO/Counter-LO Executive Commitee (LO/CLO-Excom).

JSF program vice-president Tom Burbage has said that "we are not designing multiple versions of the aircraft" but that, in addition to the multilateral operational requirements document (ORD), there are bilateral annexes signed by each export customer - so export requirements may differ from the ORD. And while there may not be different versions, there are clearly $737 million-worth of different configurations.

Moreover, then-US Ambassador Bob Schieffer told the Australian parliament in 2004 that Australia would get "the stealthiest airplane that anybody outside the United States can acquire. ...Having said that, the airplane will not be exactly the same airplane as the United States will have."

In 2006, Lockheed Martin was saying that Schieffer's "public comments two years ago should not be judged as reflective of relevant program configuration information today" but that "partner countries will receive airplanes that are compliant with their requirements". (Emphasis added.)

There is also the technical possibility that a JSF version "meets national disclosure policy" not by having sensitive technology removed from it but by incorporating anti-tamper measures. It's a possibility, but a distant one.

Thinking about this too much can drive you into the loony bin. Absent, however, from any of this discussion has been one thing: a firm unequivocal statement, from someone who knows that they are authorized to give it, that every JSF built will have identical qualities in terms of signatures.

Until then, everyone is going to wonder what that $737 million actually covers. And competitors will continue to point out that if your JSF is not as stealthy as the US JSFs in the theatre, your primary mission will be that of an armed decoy.

UPDATE:  This has launched a discussion over at F-16.net. Subject to the usual caveat - forum posters may pass as insiders even if they're 300-pound, pizza-and-Bawls-fueled, Mom's-basement-dwelling gamers - these are interesting comments:

LMAggie: "Shape is only one part of LO, another crucial part is the coatings. These coatings, and all information regarding these coatings, are export controlled and are not releasable to foreign countries. I have no clue what the path forward for the partner countries is..."

Roscoe:  "I won't even begin to describe how complex those discussion were when I was in SAF/IA, but suffice it to say the various issues brought up in this thread are but the tip of an iceberg."

Credit: Lockheed Martin