Roll SAS logic

[Tenebrae666]

Hi!

 

Reading the F14 manual and the NATOPS is giving me mixed signals. Whilst in the manual we are given recommendations to switch the SAS roll axis off to avoid damage above 15 AoA, in the NATOPS it's stated that it should be on during all phases of flight, especially at high AoA as it increases stability and gun tracking capabilities. Didn't go into much detail in my research as I'm commuting to work but I'd like to open the discussion topic to HB and the community so please chime in.

 

Please play nice...and share your opinions/testing

 

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Edited March 22, 2019 by Tenebrae666

[Deano87]

I believe the Natops manual you show is referring to a DFCS jet, or in English a jet that’s been upgraded with the Digital Flight Control System. The F-14 we have does not have this system. We use the significantly dumber AFCS which during high AoA actually ends up inputting the opposite of what you want for stability in the roll axis. This is why in an AFCS jet it’s advised to turn off roll SAS during any combat maneuvering.

[Yeti42]

Interesting note from Heatblur tester which I think is a good description of why you should turn roll SAS off during high angle of attack manoeuvring makes total sence...

"The key is that above 20 units AOA you use the rudders to roll and this works great. However, if you don't turn off roll SAS before starting these manoeuvres and try and rudder roll, SAS will try to cross control the aircraft and a departure is fairly likely."

[Tenebrae666]

Deano now that would make sense...

 

Now that we're on the subject I've noticed the roll axis SAS ends up off automatically after maneuvering at high AoA in the sim... Is that some sort of dumb pilot protection?

 

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[Oldfox]

Yesterday I did a high speed (Mach 0.8/0.9) break to evade a launch. I went immediately into a flat spin and fell into the sea from high altitude with no recovery possible (full rudder, inside engine full power.... Nothing to do :( )

 

Was so brutal I though I destroyed the plane by puling too much G's but Tacview showed max 3.5 G....

 

Wonder if that's only because of that stability system...... Or a flight model issue!!?? Before I only had flat spins by doing stupid things, this is the first time the plane kills me while I did not do something special....

[QuiGon]

Deano now that would make sense...

Have you checked the NATOPS for the F-14A? Because I guess that would still contain the AFCS, which we have in our bird.

[Tenebrae666]

Have you checked the NATOPS for the F-14A? Because I guess that would still contain the AFCS, which we have in our bird.

I was looking at the F-14B one which includes the DFCS update...

 

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[StandingCow]

Yesterday I did a high speed (Mach 0.8/0.9) break to evade a launch. I went immediately into a flat spin and fell into the sea from high altitude with no recovery possible (full rudder, inside engine full power.... Nothing to do :( )

 

Was so brutal I though I destroyed the plane by puling too much G's but Tacview showed max 3.5 G....

 

Wonder if that's only because of that stability system...... Or a flight model issue!!?? Before I only had flat spins by doing stupid things, this is the first time the plane kills me while I did not do something special....

 

 

Well... at least you dodged the missile. :megalol:

[Oldfox]

My guess is that the missile couldn't track because it was laughing too much.

[Britchot]

Yesterday I did a high speed (Mach 0.8/0.9) break to evade a launch. I went immediately into a flat spin and fell into the sea from high altitude with no recovery possible (full rudder, inside engine full power.... Nothing to do :( )

 

Was so brutal I though I destroyed the plane by puling too much G's but Tacview showed max 3.5 G....

 

Wonder if that's only because of that stability system...... Or a flight model issue!!?? Before I only had flat spins by doing stupid things, this is the first time the plane kills me while I did not do something special....

 

Please review Victory205’s lengthy explanation on spin recovery.

 

Why not use asymmetric thrust to help recovery? It may not be available, or the spin may have been induced by asymmetric thrust in the first place. Throttle transients in this extreme AOA regime can cause stalls even with the GE engines. Moving throttles will almost certainly cause stalls if they haven’t already occurred with the TF30s’ in the F14A. If you get the thrust backwards, then you are going to create an enormous, unrecoverable asymmetrical force that will be your epitaph for eternity.

[Victory205]

Yesterday I did a high speed (Mach 0.8/0.9) break to evade a launch. I went immediately into a flat spin and fell into the sea from high altitude with no recovery possible (full rudder, inside engine full power.... Nothing to do :( )

 

Was so brutal I though I destroyed the plane by puling too much G's but Tacview showed max 3.5 G....

 

Wonder if that's only because of that stability system...... Or a flight model issue!!?? Before I only had flat spins by doing stupid things, this is the first time the plane kills me while I did not do something special....

 

That's because you used improper control inputs followed by an improper recovery procedure. You deserved to crash... ;)

 

Jabbers really should pull down or update his video on maneuvering. His spin recovery is AFU and will be even worse in the F14A.

Edited March 22, 2019 by Victory205

[Tenebrae666]

I don't even go into spins...I just break the wings off straight away... #tellmegiloveher

 

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