Originally Posted by
LOMCEVAK
As there have been some comments about the Auto Wing Sweep and Manoeuvre Device System (AWSMDS) on Tornado vs the system on the F-14, I thought that I would try to add a little more detail, albeit from memory from a few years ago (30+ for the Toranado, 24 for the F-14D). The F-14 auto wing sweep was infinitely variable and set according to airspeed/Mach number. It could be manually overridden to a further aft position but not overridden further forwards. The F3 AWS set the wings to one of the cleared wing sweep angles (25, 45, 58, 63/67) and the position changed as the Normal Operating CAS/Mach limit was passed. The manoeuvre devices operated on angle of attack and the two systems were, effectively, functionally separate. It all worked as advertised during the Release to Service trials and the F3 OEU conducted their trials on it but initially had some reservations, mainly related to sweeping between 25 and 45 wing at 450 KCAS/0.73M, in particular when 'bugging out' to pitch back in at just under the 25 wing never exceed limit of 0.8M and wishing to remain in 25 wing throughout. However, when you pressed the clutch on the wings weep lever the AWS dropped out and you had normal manual wings weep. To re-engage the AWS all you had to do was press the select button on the left console behind the throttles. I have to say that my opinion was that for low type-experienced pilots the system resulted in a significant reduction in pilot workload.
The reason why the AWSMDS never entered service on the F3 was because by the time that a decision had been made to clear it (and all of the airframes had the system installed at manufacture then inhibited) the programme had slipped by a financial year (or was it 2?) and there was no funding for the maintenance test sets to be purchased so it was never activated. The Saudi ADVs, however, did have it activated. The GR1/GR4/IDS never had AWS although the Saudi IDS did have auto manoeuvres fitted. During the clearance trials an interesting characteristic was highlighted in that if the manoeuvre devices deployed during a high AOA rapid roll then a large g spike occurred which could result in an overstress especially in 45 wing.
I am interested if anyone else here has any further recollections of these systems.
I was on the F3 OEU at the time and led the tactical trials on AWSMDS. The situation was largely as LOM decribes, but there were additional considerations. As stated, the NO limits meant that the wings always moved sooner than was tactically sound, especially when taking into consideration g limits in the eventual configuration. This was also big factor in the fatigue life of the airframe as limit pulls in 58 and 67-wing were disproportionately big consumers. When the wings started to move then they would have to go to the next stop before returning (unlike the F-14). As an example, if you accelerated through 45 NO speed and then pulled a limit turn (I forget the actual figures, but 45-wing was the "best" g limit and the "best" fatigue-life wing sweep and the best subsonic tactical configuration) the wings would continue all the way to 58 during pitchback and then cycle all the way forwards to 25 (everything always ended up in 25-wing because of the lack of thrust). The wing sweep was so slow as to ensure massive energy loss during the pull as they slowly travelled nearly all the way back and then trundled forward again. So, you had lost everything you had attempted to gain (and more) because of AWS scheduling. Comparing one with and one without, it was always preferable to preset the 45-sweep at NE speed before pitchback, pull to the g limit when engaging/re-engaging and then keep going forward to 25-wing decelerating through 0.8M. What AWSMDS did provide was an increased g limit in 25-wing (slat only - memory fades, but I think above 350 KCAS below .73M) so the configuration we recommended was AWSMDS engaged with AWS manually disengaged, ie MDS, for tactical employment. Post-OCU/FRS/RTU, pilots tended to forget/miss slats more than they forgot wings.
The thing that killed it stone dead was something to do with - need rigger input here - a fragile follow-up/actuator pin in the HLWSCU (flap/wing sweep lever thingy box) that kept breaking and costing many man hours to fix. That, combined with the test equipment and fatigue issues (perhaps the latter shouldn't be a consideration, but you can only use what you've got) was enough to stop AWSMDS in the RAF.
Finally, I had plenty of bar arguments about those (and many other) recommendations, but the bottom line is you fight as you train. No one who trained hands-off AWSMDS was going to have the muscle memory to go manual "on the day", so we had to ensure that pilots maximized the always very poor energy equation (especially when training realistically and "bombed-up" with concrete AAMs and dummy bullets) while instinctively using the optimum technique. This, combined with the fatigue consideration (you can't train properly on g-limited airframes - ask me how I know after flying Lightnings) nailed the coffin shut. But it was nice for accelerations and decelerations...and navigators flying two-stickers.
PS If the jet had never had to be employed above 5000 ft the energy equation would have been very different; you could go everywhere at not much less than 600 knots for what others were using at 420. Early on, I saw 835 KIAS (M1.3) at 250 ft, still accelerating, before the canopy seal blew. It was quite exciting for about 10 seconds. At least I think that's what the Antipodean Nav said.