FAQ for F-15 AFM Development

[cofcorpse]

no, switch remains in selected position (on real F-15). We can add another command. So, we will have: one to extend, one to retract and one to hold.

 

Another option is: while you press LShift+B or LBrtl+B, speedbrake extends or retracts. If you release button, speedbrake stops

Edited April 10, 2014 by cofcorpse

[cichlidfan]

no, switch remains in selected position (on real F-15). We can add another command. So, we will have: one to extend, one to retract and one to hold.

 

Another option is: while you press LShift+B or LBrtl+B, speedbrake extends or retracts. If you release button, speedbrake stops

 

The latter would be better.

[Nefron]

 

Cursor over contacts and get details: Aircraft type, altitude, speed, possibly other fun information, including last update time.

TEWS working in concert with your radar and other inputs will show a 'ghost contact' on SIT showing expected range of the emitter threat. This information can be combined with a reliable radar hit to form an NCTR identification, aside from the actual NCTR itself.

In some cases, you can NCTR a jammer. You get the idea (you might also get the idea that we are missing a lot of symbology from the RWR. That's because we are :P )

.

 

Did not know that, it makes me want a fully modeled F-15C even more.

 

How much of this is still classified? Am I correct in assuming that there is enough information to model the systems of the F-15C on a level similar to the DCS:A-10C?

[NineLine]

The latter would be better.

 

I agree... moves while held, stops when released.

[howie87]

The latter would be better.

 

Agreed... Just make it like the A-10's

 

The 3 buttons idea sounds like a nightmare.

[blkspade]

no, switch remains in selected position (on real F-15). We can add another command. So, we will have: one to extend, one to retract and one to hold.

 

Another option is: while you press LShift+B or LBrtl+B, speedbrake extends or retracts. If you release button, speedbrake stops

 

It seems more logical to have the commands held. Given the nature of the FC aircraft control logic, there are no provisions for the middle positions for the switches on the warthog throttle.

[cofcorpse]

Ok, thanks for feedback :thumbup:

[blkspade]

There is also some annoying behavior in weapon cycling. I've only noticed it with AIM120s, but when you fire one it auto selects the next one on the same side. Due to the AFM the asymmetry then leaves one side heavy where the aircraft then rolls. You can attempt to trim it out but it never centers. You have to manually cycle through your other missiles to get it to select one on the opposite side.

[GGTharos]

The CAS should auto-trim asymmetry anyway.

[NineLine]

There is also some annoying behavior in weapon cycling. I've only noticed it with AIM120s, but when you fire one it auto selects the next one on the same side. Due to the AFM the asymmetry then leaves one side heavy where the aircraft then rolls. You can attempt to trim it out but it never centers. You have to manually cycle through your other missiles to get it to select one on the opposite side.

 

 

While a possible reportable item, please make a new thread with this and dont post it here unless its in reference to the items list in the original post. We dont want to clog up this thread and we dont want any potentially good reports lost in here either.

 

I dont know if this is how it should function or if its indeed a bug.

[mvsgas]

The CAS should auto-trim asymmetry anyway.

 

Are you sure about that? I heard that before on many aircraft ( F-16, F-117,, etc) and This aircraft do not have "auto-trim"

[GGTharos]

The CAS will do a lot of things within its authority to keep the plane coordinated and flying straight for you - that's what I hear anyway. It should basically try to deal with any un-commanded flight situation, this includes smoothing out a lot of turbulence, and this should include the roll channel. I need to dig much deeper to say for sure though, or find someone who really does know :)

 

Are you sure about that? I heard that before on many aircraft ( F-16, F-117,, etc) and This aircraft do not have "auto-trim"

[lunaticfringe]

There is also some annoying behavior in weapon cycling. I've only noticed it with AIM120s, but when you fire one it auto selects the next one on the same side.

 

That is the correct operation, since airframe F-15A-529. The reason for this can be pointed to the weight imbalance caused by the M61A1 and feed tanks, and the ability of the CAS/autotrim functionality to put it back in good order. While the simulated CAS may not be fully compensating as it should, the sequencing of per-side operation is correct, at least as far as the fuselage rounds.

 

The "natural" firing sequence of the body stations on the F-15 is

 

right forward

right rear

left forward

left rear

 

And if I remember correctly, the wing stations prioritize to the right, as well. Being that the gun is on the right side of the airframe... voila. Understand that CAS will be fixed. But don't call the sequence annoying without knowing what it's actually supposed to do, and why. There is a method to the madness.

[NineLine]

Thanks for the info LF.

 

That is the correct operation, since airframe F-15A-529. The reason for this can be pointed to the weight imbalance caused by the M61A1 and feed tanks, and the ability of the CAS/autotrim functionality to put it back in good order. While the simulated CAS may not be fully compensating as it should, the sequencing of per-side operation is correct, at least as far as the fuselage rounds.

 

The "natural" firing sequence of the body stations on the F-15 is

 

right forward

right rear

left forward

left rear

 

And if I remember correctly, the wing stations prioritize to the right, as well. Being that the gun is on the right side of the airframe... voila. Understand that CAS will be fixed. But don't call the sequence annoying without knowing what it's actually supposed to do, and why. There is a method to the madness.

[lunaticfringe]

Np, Sith- I have a lot of time studying the F-15 (and F-14), so it's good to be able to put some of it to use.

 

As to auto-trim in the F-16 and F-117, if they didn't auto-trim, you wouldn't be able to *fly* them with their inherent instability. The Wobblin' Goblin would be almost useless as a tactical aircraft without the FBW to perform input trim faster than a human ever could. While the crop of operational drivers would say the WG moniker wasn't right, it stemmed from the test period before the full control logics were implemented- they got off light.

[blkspade]

Yeah that's why I described it as an 'annoyance', rather than bug. I sensed that it may have been by design, given the -1 lists a missile reject button, which I gather sorts out this issue. If CAS should be handling it, it hasn't been.

[VTJS17_Fire]

Like moving map type arrangement similar to the Russian fighters ? Maybe linked to NAV mode or selectable toggle between Stores display and Map ?

More like the Data Link in Falcon BMS, maybe integrated in the FCR. The F-15C has Link-16/ MIDS.

 

 

B/E coordinates on FCR

I would be a beginning, if we have the bullseye coordinates on a hooked/ locked target. Actually, you can call targets only with a BRAA call. That makes only sense, if you have one (close) flight. The B/E reference for that can be set in the mission editor (already available).

 

 

SPJ

Or what is with a more real-like SPJ, like in the A-10C. It doesn't have to be a full real TEWS. But the actuall ECM does have a "warm-up" time since FC 2.0 (or earlier?). That's not real - it's only a gameplay element, which was introduced, because much online pilots did use it as a jammer (continuously on/ off to brake the lock). In the A-10C, you set the SPJ on standby and with fence in in a mode, you need it (manual, semi-auto, auto). And the Warthogs SPJ does the same ...

 

 

regards,

Fire

[uboats]

Could the F15C PFM testers share info for test:

what joystick they use and the dz, curve, saturation value

 

that we can tune our joystick accordingly and get a more closer feeling of realistic 15C flight

[mvsgas]

Np, Sith- I have a lot of time studying the F-15 (and F-14), so it's good to be able to put some of it to use.

 

As to auto-trim in the F-16 and F-117, if they didn't auto-trim, you wouldn't be able to *fly* them with their inherent instability. The Wobblin' Goblin would be almost useless as a tactical aircraft without the FBW to perform input trim faster than a human ever could. While the crop of operational drivers would say the WG moniker wasn't right, it stemmed from the test period before the full control logics were implemented- they got off light.

This is a miss use of the term/word "auto trim". The F-16 nor the F-117 have "auto trim" If you make a 30 degree bank, and let go of the control the aircraft won't stay level, it will only attempt to maintain 1g. Sorry I do not mean to derail, but I have seen this "auto trim" subject many time and mostly is a misconception. Anyway, on the F-16 and F-117, there is not automatic trim. The pilot has to actually trim the aircraft. Trim and Flight computer corrections are two very different things.

 

Why do you guys refer to the F-15 Flight Control system as "CAS"?

I though the name is AFCS (Automated flight Control System) I thought the CAS (Control Augmentation System) was part of the AFCS.

 

I guess my question remains:

- Does the F-15 ( any version) has automatic trim?

- If it has automatic trim, does it compensate for imbalances? ( Fuel, weapons, etc)

- What controls the automatic trim? ( PRCA, ARI, Feel/trim actuators)

 

The only 'auto-trim" I know of is the T/O on the F-15/ AFAIK, just sets up all surfaces to the proper take off position.

Edited April 11, 2014 by mvsgas

[Robin_Hood]

I guess my question remains:

- Does the F-15 ( any version) has automatic trim?

- If it has automatic trim, does it compensate for imbalances? ( Fuel, weapons, etc)

- What controls the automatic trim? ( PRCA, ARI, Feel/trim actuators)

 

Pitch automatic trim:

[Overvolt]

Can be put in the FAQ, radar commands and functions.

[mvsgas]

Pitch automatic trim:

 

Thanks, that information is from?

I assume "auto-trim" is only related to Roll then?

 

I am trying to look here see it explains it better but I question the validity of the site.

http://www.f15sim.com/?page_id=16

Edited April 11, 2014 by mvsgas

[GGTharos]

You need to dig around dtic.mil to find documents that are more descriptive than the -1, or if you have access to TO's, you can look up some F-15 TO's regarding this.

 

That site appears to take its info from reasonably good sources, but it doesn't go down into enough detail to model the system.

 

The system will certainly try to take out any lateral acceleration, so it will coordinate the plane for you etc. It should also correct for imbalances IIRC, obviously up to its authority.

 

Thanks, that information is from?

I assume "auto-trim" is only related to Roll then?

 

I am trying to look here see it explains it better but I question the validity of the site.

http://www.f15sim.com/?page_id=16

[mvsgas]

Unfortunately I no longer have access to Technical Order (T.O.) Thanks tho, I will look in Google see what I can find. Just interested in the subject.

From what I have seen in the site I posted a link for, and if the site is accurate, the PTC ( Pitch trim Compensator) is one of the items adjusting trim and it does this by "G". So it tries to maintain a "g" matching stick position. So like the F-16/ F-117, it will correct some things but not all. Anyway thanks guys.

[GGTharos]

Yep, but also the roll and yaw channel do their own work. Again, try dtic.mil, you will find a document called f-15 stability testing or something like this. This document might not be exactly what you are looking for but I think it will give you an idea with respect to the overall system functionality at high AoA.

 

Your example regarding the turn - yes if you roll, the nose will fall though but, if you pull g to stay level the system will do some things to help you there.

 

Unfortunately I no longer have access to Technical Order (T.O.) Thanks tho, I will look in Google see what I can find. Just interested in the subject.

From what I have seen in the site I posted a link for, and if the site is accurate, the PTC ( Pitch trim Compensator) is one of the items adjusting trim and it does this by "G". So it tries to maintain a "g" matching stick position. So like the F-16/ F-117, it will correct some things but not all. Anyway thanks guys.