F-14 random failures

[Lantirn]

I have this option enabled and once I had a total navigation computer failure so I had to navigate with TACAN. In that case I remember that actually what happened was that the aircraft position was freezed to a specific point that the failure occured so all the distances were frozen although I could switch between navpoints.

 

But I have found that I consistently have INS problems and I dont know if its related to random failures or not. 

Look at the picture below attached. Flying level confirmed by outside references and the stby horizon but the INS is banking. This happened 3-4 times. On one occasion I remember it happened after aggressive maneuvering due to a SAM avoidance, so I thought maybe that was the reason behind it.

But in this time I was just cruising on the way back. 

 

Also due to the fact that I like to have FPM (although its not that accurate here) on the hud I fly many times with LDG switch on and not CRZ. I have seen the FPM drifting from the one side to another with same stable wind while the calculated track changes on the HSI. Thats weird from time to time. 

 

Is that normal? I mean is it due to 70s technology? Is it a bug? Is it from random failures? Should I just switch off random failures?

 

PS1: Do you also like flying with FPM on or its just me?

 

PS2: Slightly off topic, so I dont open a new one, how we have to use the external lighting in the F-14 regarding anti-collision, steady or flashing, in terms of engine start, entering the runway etc.

 

[Grater Tovakia]

well you exceeded 6.5 Gs which certainly couldn't have helped However that limit was a bit more admin related and less of a hard avionics/airframe limitation. The INS will drift over time and per testimony it could in fact be unreliable at points. Honestly I would chock it up to Random Failures. Personally seems a little too offset to simply be drift, do you by any chance remember how long you were flying for?

 

 

Edited June 15, 2021 by Grater Tovakia

[Kula66]

I get systems failing or going out of alignment when I over-g, but your g meter doesn’t seem to show anything excessive. I lost my radar at the weekend, but that may have been 10+G

 

ps1: not being a real pilot, I use FPM a lot more than I probably should

Edited June 15, 2021 by Kula66

[captain_dalan]

That is odd indeed. I've had this kind of failures on a few occasions, but it was always after very hard maneuvers, like above 9g and once after a very long period of staying above 8 (this was in a lightly loaded B). But in this case, you didn't even hit 8, so i have no idea what may be the cause. Did the plane start like this from the runway or did it happen as you were flaying along?

[Lantirn]

Thanks all. 
 

No it didn’t start from the beginning, it started during the egress after about 40-50 minutes of flight. 
 

I will completely deselect the random sim failures and see what happens then.

 

If this happens on a low overcast day it’s going to be very tricky to land. 

Edited June 15, 2021 by Lantirn

[draconus]

On 6/14/2021 at 6:34 PM, Lantirn said:

PS1: Do you also like flying with FPM on or its just me?

 

PS2: Slightly off topic, so I dont open a new one, how we have to use the external lighting in the F-14 regarding anti-collision, steady or flashing, in terms of engine start, entering the runway etc.

1. You're too much used to modern western HUDs so it's normal. If you flew more russian birds or some older western ones you'd be fine. I do it by the book, so I have FPM in landing mode and that's it. I like it too but it's OK if it's gone. In the cruise or other modes - no.

2. From what I heard:

You don't use ext. lights on a boat at all with night launch exception - when you're ready to go you turn on nav lights which is meant as salute.

In the air it's mission dependent. Usually nav lights steady (plus anti-collision in dense traffic) in safe area. All lights off for fence in until fence out.

On a shore it's probably local procedures and mission dependent. Usually anti-collision on when egines on. Add taxi light plus steady nav during taxi. Landing light is self explanatory.

3. In bad weather/night you'd use compass, TACAN, ICLS, ACLS whatever brings you safely and not dependant on your broken INS.

Edited June 16, 2021 by draconus

[G.J.S]

Inertial navs, by their very definition, can tumble.
Imagine trying to gauge your position, through many turns of varying tightness, in level and the vertical, as well as oblique, all different air speeds, different acceleration rates (not G), and come up with a new position after say 20 minutes and be accurate.

Not going to happen.

Level to the horizon if visible, reset your backup ADI and use that until you can maybe sort the INS.

 

No need to fly with FPM.

[IronMike]

Your VVI is also unstable during maneuvering, because the airflow changes over the static pitot tube. So when you see your compass tape turn, it is normal that your VVI deviates, especially on the hud. The mode best to be in for cruise is A2A btw, since - you never know. Cruise itself does nothing for you, can as well turn off the HUD. It is also better to monitor your real VVI in cruise, etc than the one on your HUD. Why? Because VVI is not very reliable and laggy in itself, and thus you will find it in the proximity of the instruments you should really check: your airspeed mach indicator and your altimeter. The Altimeter is the more precise instrument out of the two, and the rad alt will only be displayed on your hud when low and in landing config.

 

If your hud tape is tilted sideways, than you have some kind of INS or IMU failure, etc. Usually this is from pulling too much G. When flying long, from drift. When launching from the carrier, from the catapult (can screw up your gyros). When random failures are on, then it comes from that. Note: the INS was one of the things that went haywire every now and then. Hence we also modelled the ability to lose it when shooting off the catapult, etc (even if random failures are off). And we simulate it very deeply, this means: if you expose your gyros to forces they do not withstand, you will break it.

Edited June 19, 2021 by IronMike