Autopilots on modern fighters

[just another jocky]

111 - both the sim and in the air....a routine BTR (Basic Training Requirement). The numbers you are looking for are 25/45/67, though with the larger Hindenbuger underwing fuel tanks, there is a limit of 63 on the wings to prevent taileron/tank interaction.

[Treble one]

Many thanks for the confirmation and numbers just another jocky.


Sounds like an interesting landing

[orca]

Now, let me make this perfectly clear. I love thread drift. I think it's inherent in threads in the first place. I find it incredibly tiresome when the inevitable cry of thread drift, usually with a plea for moderators to close the thread, comes from the self appointed policemen of pure and polarised discussion.

I just wanted to point out that someone asked a question about autopilots on modern fighters and within 2 pages we were discussing Tornado wing sweep and BTRs. Where to next I wonder? Give it two more pages and we'll be discussing our favourite kebab vans.

[LOMCEVAK]

OK, back to the thread! In the late '80s we flew a trial on the auto ILS mode (APP) in the Tornado GR1. There were two problems: First, the gains for the drive laws varied as a function of the rad alt signal and, as has been mentioned previously, the early rad alts locked up to the nose leg when the landing gear was down. This then resulted in the wrong gains being used by the autopilot and erratic localiser following. However, later standards of rad alt solved that problem so this was not insurmountable.

However, the bigger problem was that the system used the selected course (set on the HSI) and heading, rather than track, to maintain the localiser. Basically, when the aircraft was on the localiser the AFDS turned the aircraft to match the heading with the set course. Therefore, if there was a crosswind the aircraft flew inbound displaced downwind from the localiser. We recommended having a crosswind limit for coupled approaches (and I think that about 20 kts would have been feasible) to limit lateral displacement such that a sidestep could be flown from Decision Height and a landing could be made. However, 'the Company' solution was to adjust the course setting by a factor of the drift angle (can't remember exactly what the factor was but 1/2 comes to mind). The scope for getting it wrong was monstrous so we would not endorse this but we could not get support for the crosswind limit option. However, without any significant crosswind it worked quite well.

The F3 had the same system as the GR1 and the GR4 does also. I have tried it in the GR4 sim and it usually ends up with a divergent oscillation down the localiser but in fairness it is not cleared in the aircraft so the drive laws in the sim were never required to be refined.

[27mm]

Jocky mate, don't forget 58 sweep.....

[stilton]

Trivia question, could slats / flaps be extended on the Tornado unless the wings were fully swept forward ?

[just another jocky]

Flap and slat at 25, slat only beyond that up to 45, nothing beyond that.

[Onceapilot]

Then there is manoevre flap/slat and 33wing.

OAP

[Moi/]

^^


Part of the groundcrew funcs would be to sweep the wings, and lower the flaps. I guess always an eary feeling, hoping the Wing Sweep micro-switches were set correctly...


I heard that they have been lowered with them rearwards...but that's engineering for you... It if can be fitted the wrong way, it probably will be..

[Moi/]

On a similar tale...


Jags... installed a relay, however did not polarise it. Cue undercarriage funcs... instead of funcs at a lower pressure, full pressure... Main Leg through door..

[LOMCEVAK]

OAP,

I think that you mean 35 wing.

[Dominator2]

Since there was no detent, he was allowing for parallax!

[Onceapilot]

LOM,
Depends how heavy you are.

OAP

[stilton]

Great information Gents, thank you.