ACLS questions

[twistking]

Hello,
i'm making good progress with the Hornet + carrier but still struggle with the ACLS. Maybe you can help me a littel bit.

1. The ACLS mode 1 coupled autopilot does only control pitch and roll, not throttle. Is this correct?

2. If so, does the ATC (auto throttle) still controls the throttle for a set airspeed (like in normal operation) or does ATC (auto throttle) mode change in landing configuration?

3. If ACLS mode 1 coupled autopilot does indeed only control pitch/roll and ATC still only controls for a set airspeed, this means that altitude changes are made via pitch while throttle manages speed. I was under the impression that for Hornet carrier landings (as well as most other aircraft) pitch is used to hold AOA and throttle is used for altitude/sink-rate. Does the mode 1 operation function fundamentally different, or should i also use pitch for altitude/sink-rate when flying the hornet manually?

4. I have a problem that when i get the mode1 option and i push the coupled AP button, the AP does not engage. However i don't know if it registered or if i should continously press the button until it engages. Is it enough to push it a single time and just wait until eventually engages? Does it want me to properly align with the ACLS pole-thingy to engage?

5.a) If my assumptions from 1) and 3) are correct: If AP finally engages and i don't have ATC (auto throttle) engaged, i just manage my throttle for airspeed (i think 140 it is for the hornet). Correct?
5.b) Can i also manually fly (without AP) and have ATC (auto throttle) on (obviously i would disengage it before touchdown to go full mil)?

Thanks.

Edited July 10, 2022 by twistking

[Hippo]

13 hours ago, twistking said:

Hello,
i'm making good progress with the Hornet + carrier but still struggle with the ACLS. Maybe you can help me a littel bit.

1. The ACLS mode 1 coupled autopilot does only control pitch and roll, not throttle. Is this correct?

Yes.

13 hours ago, twistking said:

2. If so, does the ATC (auto throttle) still controls the throttle for a set airspeed (like in normal operation) or does ATC (auto throttle) mode change in landing configuration?

From NATOPS

2.1.2 Automatic Throttle Control (ATC). The automatic throttle control is a two mode system that
automatically maintains angle of attack (approach mode) or airspeed (cruise mode) by modulating
engine thrust in the range of flight idle through military. Automatic transition between the two modes
or single-engine engagement is not possible. When either mode is engaged, the ECS air to the torque
boosters is shut off, the throttles are initially backdriven, a stop is extended in the power lever control
(PLC) to limit throttle travel from flight idle to MIL, and an ATC advisory is displayed on the HUD.
If either mode does not engage when selected, or automatically disengages after engagement, the ATC
display flashes for 10 seconds and is then removed from the HUD. If a force of approximately 12
pounds (with friction off) is applied to either throttle the system automatically disengages. This force
is sufficient to permit the hand to follow throttle movement without causing disengagement. It is
recommended that the friction lever be in the full aft position and both throttles set between flight idle
and MIL before engaging ATC. If a mechanical failure occurs, a force of approximately 68 pounds (with
friction off) is required to override the system. When either mode is engaged, changing the FLAP

switch between AUTO and HALF or FULL automatically disengages the system. If the system is
disengaged for any reason, it remains disengaged until reengagement is initiated by the pilot.

                                                                        NOTE

                   Momentary force applied to the throttle(s) (throttle rap) may not
                   disengage the ATC system. The force must be applied and held for a
                   minimum of 0.10 second.

                   If the ATC commands the throttles to MIL, it may not be possible to
                   manually advance the throttles into the afterburner range without first
                   disengaging the ATC through momentary throttle reduction using more
                   than 12 pounds of force.

   If the throttle(s) are being held against the flight idle or MIL stop as ATC is disengaged, the stops
may not disengage until pressure is removed from the throttle(s).

2.1.2.1 ATC Approach Mode. The ATC approach mode is engaged by pressing and releasing the
ATC button on the left throttle with the FLAP switch in HALF or FULL and the trailing edge flaps
extended at least 27°. When ATC is engaged in the approach mode, the flight control computer
modulates engine thrust to maintain on-speed AOA. The computer uses inputs of AOA, normal load
factor, stabilator position, pitch rate, and angle of bank to generate command signals. These signals
drive the engine mounted throttle control units which in turn command the engine fuel controls. The
computer uses AOA as the primary input to generate command signals. However, normal load factor
provides increased stability, stabilator position provides increased or decreased thrust for pilot induced
pitch changes, pitch rate provides lead during pitch maneuvers, and bank angle provides additional
thrust during banking maneuvers. Normal disengagement is accomplished by pressing the ATC button
or applying and holding force to either throttle. Automatic disengagement occurs for the following
reasons:

    Flap AUTO up
    AOA sensor failure
    Two or more failures of either trailing edge flap
    Trailing edge flap deflection less than 27°
    ATC button fails
    FCES channel 2 or 4 fails
    WOW
    FCS reversion to MECH or to DEL in any axis
    Left and right throttle angles differ by more than 10° for more than 1 second
    Bank angle exceeds 70°
    Any internal system failure
Selection of GAIN ORIDE

 

2.1.2.2 ATC Cruise Mode. The ATC cruise mode is engaged by pressing and releasing the ATC
button on the left throttle with the FLAP switch in AUTO. When ATC is engaged in the cruise mode,
the existing airspeed is used by the flight control computer to modulate engine thrust to maintain this
existing airspeed. The existing airspeed is the airspeed being sent from the ADC to the flight control
computers via the mission computers. An ADC failure inhibits the ATC cruise mode of operation. The
FCC uses true airspeed from ADC via the mission computers at the time of engagement to generate a
command signal. This signal is then used as a reference to generate an error signal that drives the
engine mounted throttle control units. Normal disengagement is accomplished by pressing the ATC
button or applying and holding force to either throttle. Automatic disengagement occurs for the
following reasons:

    Flaps HALF or FULL
    ATC button fails
    FCES channel 2 or 4 fails
    FCS reversion to MECH or to DEL in any axis
    Left and right throttle angles differ by more than 10° for more than 1 second
    ADC true airspeed failure
    ADC degrade
Any internal system failure

 

13 hours ago, twistking said:

3. If ACLS mode 1 coupled autopilot does indeed only control pitch/roll and ATC still only controls for a set airspeed, this means that altitude changes are made via pitch while throttle manages speed. I was under the impression that for Hornet carrier landings (as well as most other aircraft) pitch is used to hold AOA and throttle is used for altitude/sink-rate. Does the mode 1 operation function fundamentally different, or should i also use pitch for altitude/sink-rate when flying the hornet manually?

See above, and you would use pitch (i.e. the stick, gently) to control rod, and the ATC will attempt to maintain AoA.

13 hours ago, twistking said:

4. I have a problem that when i get the mode1 option and i push the coupled AP button, the AP does not engage. However i don't know if it registered or if i should continously press the button until it engages. Is it enough to push it a single time and just wait until eventually engages? Does it want me to properly align with the ACLS pole-thingy to engage?

It is enough to push it a single time.  With SC, for the acl to work properly depends on radio calls being made at the right time.  This is probably the most likely reason you might be having problems.  Although, supposedly, if you have T/C CPL engaged you have to push it twice, once to disengage T/C CLP, and again to engage P/R CPL, but that's a story for another day.

13 hours ago, twistking said:

5.a) If my assumptions from 1) and 3) are correct: If AP finally engages and i don't have ATC (auto throttle) engaged, i just manage my throttle for airspeed (i think 140 it is for the hornet). Correct?

I've not actually tried this so I don't know, though I can't see why not.  Speculation follows.  It's possible that for the DCS version to "work" ATC needs to be engaged?? It is more correct to say that you are managing AoA rather than airspeed.  You would be using the throttle to keep the fpm in the centre of the e-bracket.  This will correspond to a specific airspeed dependent on aircraft configuration.

13 hours ago, twistking said:

5.b) Can i also manually fly (without AP) and have ATC (auto throttle) on (obviously i would disengage it before touchdown to go full mil)?

Thanks.

 

Yes, it is supposed to be perfectly acceptable to engage ATC on a case I on downwind once the aircraft is level and on AoA (and fly the aircraft to touchdown in this state).  It will certainly work in your  scenario.  As per the natops, the act of going full mil quickly should automatically disengage ATC, and it does indeed do so in DCS (so no need to do it manually before touchdown).

See also:

 

Edited July 11, 2022 by Hippo

[twistking]

On 7/11/2022 at 11:15 AM, Hippo said:

[...]

Thanks a lot for the detailed information!!! I hadn't had time to fly since, but will give it a another go this weekend...

[Trini86]

Does anyone know if the Superbug works with the update of the ACLS system?

 

 I tried it but when I hit couple after it tells me “ACLS lock on say your needles” it shows “CPLD heading “ not  “CPLD P/R”

[pokeraccio]

On 7/20/2022 at 12:34 PM, Trini86 said:

Does anyone know if the Superbug works with the update of the ACLS system?

 

 I tried it but when I hit couple after it tells me “ACLS lock on say your needles” it shows “CPLD heading “ not  “CPLD P/R”

maybe are the same bugs the F18C is having when there are other flights

[9thHunt]

On 7/10/2022 at 1:07 PM, twistking said:

5.a) If my assumptions from 1) and 3) are correct: If AP finally engages and i don't have ATC (auto throttle) engaged, i just manage my throttle for airspeed (i think 140 it is for the hornet). Correct?
5.b) Can i also manually fly (without AP) and have ATC (auto throttle) on (obviously i would disengage it before touchdown to go full mil)?

Thanks.

 

5.a) more or less, yes.  The goal of maintaining "On Speed" during an approach isn't so much holding a solid number as holding the right speed for your angle of attack.  Don't worry about holding an exact number, just keep the velocity vector in the E-bracket.

5.b.) Yes, if you are in the right configuration for landing, ATC will still go into approach mode.  IIRC, it doesn't even need the AP on or a localizer.  You don't need to manually disengage ATC either, just move the throttle handles and it will disconnect.