F-14 flight control system

[Hummingbird]

Been reading abit about the F-14's flight control system and I cannot quite discern wether the F-14 features an automatic pitch trim system or wether it is mostly manual trim. What I did read was that it only features 5 five trim positions in the manual mode, which seems abit strange incase it lacks auto trim.

 

However auto trim is mentioned, specifically for compensating for mach trim changes.

 

Anyone with more knowledge on this could who could add abit more insight into this? :)

[sLYFa]

Trimming is provided by a trim actuator which itself consists of two electric trim drives.

The first one is used for manual (without stages thou, dont know where you got that info) trimming and auto-trimming, which only works in conjunction with the autopilot.

The second one is used for mach trim compensation in the transsonic and supersonic speed range and is continously active regardless of AP state.

Therefore, you will not need to re-trim your aircraft when going supersonic, however you will have to re-trim e.g. for gear and flaps configuration changes. The auto-trim feature you mentioned is only a part of the autopilot and therefore works only when the autopilot is engaged.

That all goes for the A model, dunno if the D had a more sophisticated FBW-like control system

Edited October 29, 2015 by sLYFa

[Hummingbird]

Trimming is provided by a trim actuator which itself consists of two electric trim drives.

The first one is used for manual (without stages thou, dont know where you got that info) trimming and auto-trimming, which only works in conjunction with the autopilot.

The second one is used for mach trim compensation in the transsonic and supersonic speed range and is continously active regardless of AP state.

Therefore, you will not need to re-trim your aircraft when going supersonic, however you will have to re-trim e.g. for gear and flaps configuration changes. The auto-trim feature you mentioned is only a part of the autopilot and therefore works only when the autopilot is engaged.

That all goes for the A model, dunno if the D had a more sophisticated FBW-like control system

 

According the POH the manual pitch trim button on the stick is a five-position switch, so that is where I got that from :)

 

That having been said I was looking into wether the F-14 automatically adjusts pitch with changes in speed, or wether it needs constant trimming. According to what I've heard it features automatic trim in pitch, but the manual I read doesn't seem to mention this.

[sLYFa]

ah now I understand. The five positions mean the trim switch (which is like a POV hat on a joystick) has 5 positions: neutral, Left wing down, Right wing down, nose up, nose down. It does NOT mean there are 5 distinct trim positions, just four directions (plus the neutral position) to move the trim switch to to trim the respective control surface (pitch or roll)

And the autotrim feature works only in the trans/supersonic range to account for shockwave induced neutral point shift. In the subsonic range, you need to trim manually to keep level flight (like in the a-10 for example)

Edited October 29, 2015 by sLYFa

[Hummingbird]

Yeah thats what I gathered from reading the manual, and it seems to be the same with the B & D version. That having been said supposedly the F-14 requires extremely little trim with changes in speed, this might be due to the automatic wing sweep changing?

[hannibal]

after watching aerosoft FSX version of F14 tomcat with its TF30 engines working the compressor stall procedures, i am getting turned off by this deficiency of the F14A... :/

 

will be interesting to see LN's implementation..

maybe too real in which its totally dangerous to fly a tomcat!

[sLYFa]

Ive been flying the aerosoft f-14 for a while. Its a decent rendition and the compressor stalls are actually not THAT bad. You have to keep an eye on AoA and engine RPM. And keep in mind that the aerosoft f-14 models the engine stall in a rather simple way i.e. the engine suddenly flames out, while a real engine would give you some signs of a compressor stall building up, which means you should get some time to react.

[Hummingbird]

Hannibal keep in mind that we will also be getting the B model with the much improved GE engines that didn't suffer any compressor stalls :)

[captain_dalan]

Ive been flying the aerosoft f-14 for a while. Its a decent rendition and the compressor stalls are actually not THAT bad. You have to keep an eye on AoA and engine RPM. And keep in mind that the aerosoft f-14 models the engine stall in a rather simple way i.e. the engine suddenly flames out, while a real engine would give you some signs of a compressor stall building up, which means you should get some time to react.

This. The Aerosoft version (which i fly and love) is a rather this or that implemented. You either flame out or don't, which generally means you do. It's way to sensitive in that regard, but it's not their fault, it's just sim engine limitation. Even with that though, it's still not that major issue once you learn how to fly it properly, which for me at least is part of the pleasure and authenticity :thumbup:

[BlackLion213]

This. The Aerosoft version (which i fly and love) is a rather this or that implemented. You either flame out or don't, which generally means you do. It's way to sensitive in that regard, but it's not their fault, it's just sim engine limitation. Even with that though, it's still not that major issue once you learn how to fly it properly, which for me at least is part of the pleasure and authenticity :thumbup:

 

I agree. The TF30s were really troublesome for me at first, I would have 3-4 compressor stalls/flame-outs per flight - and not when I was trying to provoke them. ;)

 

After a few weeks of flying and learning things like how quickly to move the throttles and avoiding adverse yaw at high AOA - I stopped having them. It was a surprisingly big change after just a bit of practice.

 

If you fly the F-14A as the manual recommends, keeping out of trouble isn't too hard, at least during normal operations. ACM could be a different story, that will also take practice.

 

You just need to respect them and they will serve you well. Learning how to do that is a big part of the fun. :)

 

In any case, the F-14B will have none of these issues. Those F110s are pretty indestructible.

 

-Nick

 

PS - I agree with the Captain, the LNS F-14A will probably be more nuanced with the engine modeling and stalls. The Aerosoft version is excellent, but FSX/P3D limits the accuracy of limiting stalls. Still, I really appreciate what they accomplished - it got be back into sim-ing.

Edited October 30, 2015 by BlackLion213

[Hummingbird]

How do you guys find the trimming to be in Aerosoft? As mentioned I've been told that the real aircraft requires unusually little trimming in pitch with speed, supposedly because of the automatic wing sweep moving the center of lift further backwards with speed.

[captain_dalan]

Lacking a dedicated trim input on my stick (the hat being tied to the pan/view) i find the trimming a bit bothersome and i avoid it if possible. I use it only on long monotone flights from point A to point B, but almost never on landings and absolutely never during ACM. I just feel that the plane doesn't need it enough for me to bother around it. This may change if i get a new HOTAS though.