Flight Model

[Rainmaker]

1 hour ago, Holbeach said:

@KlarSnow

 

The CAS and PTC are connected with the same hydro pipes to the servos, within the PRCA, but as you say, turn off the CAS and there's barely any noticable difference, auto trim still works perfectly.

It was most noticeable in the T/O run, which was more difficult to rotate, but turning off the CAS, was less dramatic than I expected.

Thanks for the reply.

..

Hydro pipes?  No, that’s not really how that all works.  Hydo is just a power source, CAS and mech are not that way. 

[Holbeach]

53 minutes ago, Rainmaker said:

Hydro pipes?  No, that’s not really how that all works.  Hydo is just a power source, CAS and mech are not that way. 

I'm just going by the circuit diagram, which shows hydraulic pipes and mechanical conections, shared between the CAS Interconnect and PTC.

These pipes go to the boost actuator.

Bare in mind, I,ve never said CAS is required for auto trim, just that they are connected in the PRCA.

Edited July 20, 2023 by Holbeach

[Holbeach]

21 hours ago, eFirehawk said:

Wait a sec, so you're telling that the F-15E can actually trim itself? Have I been flying it wrong all along? I am away for 3 weeks so can't play DCS to confirm, but in no tutorial I remember anyone talking about the pitch ratio switch. So the condition for auto-trim to be enabled are: All 3 CAS switches to on, PLUS pitch ratio to Auto?

Pitch Trim Compensator is on all the time. Pitch and Roll ratio are the only pilot controls and should be on for normal operation.

CAS is not required for auto trim, but should be on all the time.

..

[Rainmaker]

1 hour ago, Holbeach said:

I'm just going by the circuit diagram, which shows hydraulic pipes and mechanical conections, shared between the CAS Interconnect and PTC.

These pipes go to the boost actuator.

Bare in mind, I,ve never said CAS is required for auto trim, just that they are connected in the PRCA.

 

CAS connects directly to the actuators.  Mech is primarily control rods and linkage. The two are not really the same, hence why they are not reliant on each other to an extent, which is by design. 

[Rainmaker]

22 hours ago, eFirehawk said:

Wait a sec, so you're telling that the F-15E can actually trim itself? Have I been flying it wrong all along? I am away for 3 weeks so can't play DCS to confirm, but in no tutorial I remember anyone talking about the pitch ratio switch. So the condition for auto-trim to be enabled are: All 3 CAS switches to on, PLUS pitch ratio to Auto?

Pitch ratio has to do with mech gearing ratio for stick vs surface travel. Not really related to trimming for commanded G flight.  There are ways to disable the PTC however if necessary. 
 

CAS is also not really in the loop on this. Trimming is done regardless and based on the mech side of the flight control system. Will operate in either fashion, CAS on or off. 

Edited July 20, 2023 by Rainmaker

[felixx75]

On 7/19/2023 at 1:23 PM, KlarSnow said:

...so after takeoff you have to trim it back to 1G. After that it should be hands off for pitch.

How do I know/see, that it's back at 1G?

[Duck21]

52 minutes ago, felixx75 said:

How do I know/see, that it's back at 1G?

If you can release your stick pitch axis in neutral without pitch changing on its own basically equals being trimmed for 1G, but obviously only if you are not flying a crazy pitch angle.

[jaylw314]

56 minutes ago, felixx75 said:

How do I know/see, that it's back at 1G?

When the velocity vector stays stops moving up or down? There's also the G display in the HUD, since you don't have buttocks in the seat to feel it

 

[felixx75]

Ok, so I'm not blind and did not oversee any hidden gauge

[Rainmaker]

Ctrl Enter will also show the trim position. If you dont have damage, etc, center of the cross should be 1G. I have a ‘wish list’ request of my own to open up the null range a little bit so its not quit so sensitive.