VSN New F-104 Mod

[PeeJott17]

On 6/28/2025 at 12:34 AM, AndyJWest said:

I've been trying out the C model. Looks are excellent, but I'm a little unsure about the flight modelling. I can understand it being sensitive in pitch, but it seems to actually be divergent in roll: trimmed hands off, it will fairly rapidly roll off to one side or another, to an extent that I'd have thought unacceptable in a real aircraft. Is stability augmentation working? Turning roll augmentation off via the switch seems to make no difference.

Yes, it does roll slightly to the down-wing-side.

I think(and it is not 100% clear from the manual, at least to me) that the stability-augmentation just countered stronger rolling and dampened it. I don't know whether it could completely counter rolling or just set it to a linear slight rolling.

As far as I know, the 104 did not go straight through turns if you took your hands of the stick, but I'll look into it

On 6/28/2025 at 5:58 AM, zsoltfireman said:

It would be nice to have a G/S model package that can be used without FC in the same way as the C package

Yep, sure thing. But G and S will stay FC-3 dependent...of course, you never know, but it is more looking like "will not happen" than "may-be"...

 

[stockfisch]

I am puzzled. In the video ‚F-104C mod - first flight‘ of cesarferrolho it seems to be a F-104G model with the long rudder and without probe. The cockpit is clickable. Is it some kind of a ‚franken plane‘? Would love to combine the exterior model of the F-104G with the F-104C standalone clickable cockpit features. Is it possible?

Thanks for your answers. Good to know that it is possible to use G-type skins to get the F-104G exterior look for the C-Model.

[AndyJWest]

2 hours ago, PeeJott17 said:

Yes, it does roll slightly to the down-wing-side.

I think(and it is not 100% clear from the manual, at least to me) that the stability-augmentation just countered stronger rolling and dampened it. I don't know whether it could completely counter rolling or just set it to a linear slight rolling.

As far as I know, the 104 did not go straight through turns if you took your hands of the stick, but I'll look into it

Yep, sure thing. But G and S will stay FC-3 dependent...of course, you never know, but it is more looking like "will not happen" than "may-be"...

 

There are flight manuals for various versions of the F-104 about, and some of them include a section on 'Flight Characteristics'. I've not found one for the C version with this, but the basic aerodynamics won't have changed. The section goes into a fair bit of detail regarding why, despite the 10° anhedral (on what is almost an unswept wing), due to the T-tail acting as a fence on the rudder/fin, inducing greater roll in a slip, "the aircraft possesses a normal positive dihedral effect". This to me would suggest that the aircraft should be at least a little more stable in  roll.

The same section also has data on the stability augmenters, showing their damping effect diagrammatically. I seem to remember one of the manuals stating that the roll augmenter should be turned off in some circumstances (above a certain speed, with missiles/tanks on the tip stations, I think), but I can't seem to find it. This would imply that even without the roll augmenter, it should still be stable in roll.

[PeeJott17]

3 hours ago, AndyJWest said:

There are flight manuals for various versions of the F-104 about, and some of them include a section on 'Flight Characteristics'. I've not found one for the C version with this, but the basic aerodynamics won't have changed. The section goes into a fair bit of detail regarding why, despite the 10° anhedral (on what is almost an unswept wing), due to the T-tail acting as a fence on the rudder/fin, inducing greater roll in a slip, "the aircraft possesses a normal positive dihedral effect". This to me would suggest that the aircraft should be at least a little more stable in  roll.

The same section also has data on the stability augmenters, showing their damping effect diagrammatically. I seem to remember one of the manuals stating that the roll augmenter should be turned off in some circumstances (above a certain speed, with missiles/tanks on the tip stations, I think), but I can't seem to find it. This would imply that even without the roll augmenter, it should still be stable in roll.

I will take a look at it and hope to find an answer to it for the next Version;-)

[firefox121]

Hello, this is a grat mod, indeed I noticed that has no ffb effects,  is ther any chance to add ffb effects to this great mod? without using external software, I own an old sidewinder ffb 2

[Bremspropeller]

Hey @PeeJott17 thanks for the very nice mod!

 

Here are some thoughts I had after throwing the jet around (version 2.9.16.099):

- The engine gauge (small dial) seems to read 0.1% percents, while it should read whole percents.

- The engine-response needs to be quicker (see F-4E for reference - about 4s idle to MIL)

- The engine seems to have too much thrust in MIL and in blower relative to the available lift/drag, which also seems slightly high. On the deck I have trouble keeping speeds below 450 (flaps T/O) and maintaining 7g in burner, which suggests too much thrust (and lift!) in blower and flaps T/O. I can even maintain higher g than that. A somewhat similar behaviour with flaps up and in MIL at about 500KIAS: Not enough drag and I'll have to go to just below 5 on the APC gauge to make her slow down at all. With the -7 motor, the jet should be a bit more thrust-limited during those turns. The -19 motor in a late A might be a different story altogether.  Config tested was two AIM-9Bs on the tips.

- Roll-response is too sluggish. The jet should roll WAY quicker. Roll damping seems okay to me, though.

- Pitch generally seems alright, even though I believe there's a little too much lift in those wing-stubs and I barely need to use the T/O flaps to make the nose come around when flying clean.

- The rate-shaker is probably hard to implement.

Are you planning to implement the kicker and the APC-cutout function for the kicker in the future? The C seems to not have a paddle-switch for the kicker, though. I personally believe the pitch-up is a bit too high-gain and should have a smoother and somewhat more controllable, yet progressive onset. Modelling might be very hard, though.

Edited June 30 by Bremspropeller

[Bremspropeller]

On 6/28/2025 at 12:34 AM, AndyJWest said:

I've been trying out the C model. Looks are excellent, but I'm a little unsure about the flight modelling. I can understand it being sensitive in pitch, but it seems to actually be divergent in roll: trimmed hands off, it will fairly rapidly roll off to one side or another, to an extent that I'd have thought unacceptable in a real aircraft. Is stability augmentation working? Turning roll augmentation off via the switch seems to make no difference.

Did some more testing yesterday and I can second that. Taking off in a crosswind will dip the wing immediately on liftoff and the jet won't keep the wings level when trimmed for hands-off flying.

Generally, the jet should stay where you last pointed it.

 

Also, how do I get the tanker to talk to me? I tried building a mission to sip some gas, but the tanker won't answer my calls. The radio was hard-tuned to same freq (251) via the ME. I also tried fumbling with the radio (TR and TR+G) but the tanker seemed to not care about my calls anyway, despite calling "on station".

Edited Wednesday at 11:08 AM by Bremspropeller

[Dogsbd]

I can also confirm the roll axis instability. If the aircraft is tending to roll left it takes a good bit of right stick deflection to get it back toward neutral but as soon as it reaches a level/neutral roll position that right stick deflection pushes it past level and into a right roll. It's like trying to balance a basketball on your pinky finger.

[cesarferrolho]

On 7/2/2025 at 12:07 PM, Bremspropeller said:

Did some more testing yesterday and I can second that. Taking off in a crosswind will dip the wing immediately on liftoff and the jet won't keep the wings level when trimmed for hands-off flying.

Generally, the jet should stay where you last pointed it.

 

Also, how do I get the tanker to talk to me? I tried building a mission to sip some gas, but the tanker won't answer my calls. The radio was hard-tuned to same freq (251) via the ME. I also tried fumbling with the radio (TR and TR+G) but the tanker seemed to not care about my calls anyway, despite calling "on station".

Did you make sure you are using a Tanker with basket? Like the KC-135 MPRS, for instance

[Bremspropeller]

28 minutes ago, cesarferrolho said:

Did you make sure you are using a Tanker with basket? Like the KC-135 MPRS, for instance

I used a KC-130 to LARP a KC-95. 

[Bremspropeller]

One more observation also feeding into the "too much thrust" bucket:

Approach should be 87-90% RPM with land flaps. I do have to put the boards out to make those numbers work. Without boards, I'll have to go to 80'ish percent, which IRL would cut off BLC bleed air (most likely asymmetrically) and ruin the whole day...

 

[Dogsbd]

7 hours ago, Bremspropeller said:

One more observation also feeding into the "too much thrust" bucket:

Approach should be 87-90% RPM with land flaps. I do have to put the boards out to make those numbers work. Without boards, I'll have to go to 80'ish percent, which IRL would cut off BLC bleed air (most likely asymmetrically) and ruin the whole day...

 

I believe the bleed air for the flaps cuts out below ~82-83%....