AJ-37 80s payload question

If the outer pylons were enabled only in the early 90s, how come in DCS we can use them but only with old, rear-aspect RB24 versions of the Sidewinder? You'd think they'd be used for the RB74s all-aspect ones like the inner pylons...

That's how the swedes wired the pylons. My guess is that they didn't see the need to mount the RB 74 on the outer wing pylons when the delivery of the Gripen was around the corner. That, or there was technical difficulties in doing so.

That's how the swedes wired the pylons. My guess is that they didn't see the need to mount the RB 74 on the outer wing pylons when the delivery of the Gripen was around the corner. That, or there was technical difficulties in doing so.

That's interesting, thanks for the reply.

If the outer pylons were enabled only in the early 90s, how come in DCS we can use them but only with old, rear-aspect RB24 versions of the Sidewinder? You'd think they'd be used for the RB74s all-aspect ones like the inner pylons...

TL;DR: The old RB24 missiles were lighter than the RB74 and intended for self defence.

Detail:

There is a story behind it in the book System 37 Viggen.

 

Originally the pylons were designed for the RB28 Falcon (AIM-4C) during aircraft development. This was at the time the standard IR missile for the J35 Draken. The missile had better performance than the early RB24 (AIM-9B). But it also had it's drawbacks especially since the missile become unusable after it had been used for aiming due to its battery being activated.

 

This ment the airforce looked towards the sidewinder series again and managed to buy the RB24J (Modified AIM-9J).

 

The airforce asked SAAB several times if they could fit the RB24J on the outer pylons but the answer always became NO after the engineers had done their calculations regarding fatigue in the wing. This due the RB24Js weight of 81kg vs RB28s weight at 61kg.

 

When it was time for the AJS upgrade the Airforce did a final push and asked again with a little rephrased question. "For how many flighthours can we carry the RB24J if we add it?"

 

The engineers at SAAB went back the their calculations and came up with the answer of 100 hours. This settled the deal and the modification to finally carry the RB24J got implemented.

 

The RB74 is about 5 kgs heavier but with the extra launch rails it would have added weight further and given a more limiting flighttime. Also the priority was to use the RB74s on the fighter version primarily as the attack version is only carrying its offensive weapons as a last resort of self defence.

before the TERNAV how the viggen worked, does anyone know?

before the TERNAV how the viggen worked, does anyone know?

Exactly like it does in the AJS 37 when you disable TERNAV. The nav system just drifts a bit more noticeably because the TERNAV isn't there to take fixes for you automatically.

Here's an anecdote for you, though: when the original AJ 37 was complete and Saab started working on the updated and modified JA 37, they figured they wanted a better navigation system, so they went off and bought a fancy new Kearfott inertial navigation unit from the US, complete with an integrated computer. That was nice, because they could then move over all the nav calculations from the central computer to the inertial unit's own computer and just not worry about that - or so they thought. In the test aircraft they still had the logic in the central computer, so to get things working for the moment, they hacked up some bits of programming that let the computer in the inertial navigation unit emulate the analog interface the old AJ 37's unit had used and kept the calculations in the central computer. And it worked, the test aircraft flew with this hack, and then it just sorta lived on (since it worked, after all) and it got into production and in the end all JA 37's flew that way until retirement. The fancy computerized nav unit pretended to be the AJ 37's old analog one for compatibility reasons for the entire career of the aircraft.

:O amazing!! very good data, and many thanks!

good that means that deactivating the TERNAV and limiting the payload would practically have a AJ-37 eighties?

or would something else be missing?