HALF, FULL FLAPS BEHAVIOR

[GumidekCZ]

Hi,

As I read the F/A-18C manual (not DCS one), I noticed one thing. Which is that mathematic function is controlling position of leading and trailing flaps on basis of measured AOA and speed:

HALF

Below 250 knots, leading edge flaps are scheduled as a function of AOA. Trailing edge flaps and aileron droop are scheduled as a function of airspeed to a maximum of 30° at approach airspeeds. Above 250 knots, the flaps operate in the auto flap up mode and the amber FLAPS light comes on. On the ground, the leading edge flaps are set to 12°. The trailing edge flaps and aileron droop are set to 30°. With the wing unlocked, aileron droop is set to 0°.

 

 

FULL

Below 250 knots, leading edge flaps are scheduled as a function of AOA. Trailing edge flaps and aileron droop are scheduled as a function of airspeed to a maximum of 45° flaps and 42° aileron droop at approach airspeeds. Above 250 knots, the flaps operate in the auto flaps up mode and the amber FLAPS light comes on. On the ground, the leading edge flaps are set to 12°. The trailing edge flaps are set to 43° to 45° and aileron droop to 42°. With the wings unlocked, aileron droop is set to 0°.

I was curious and tried the behavior in DCS, what I noticed there was that FLAPS didn’t come down lineary with AOA and speed, rather than small/big steps. For example when under 230 kts FULL Flaps selected, 30° is set in matter of seconds causing plane to small jump in air and pitching nose up. When slowed down around 150 kts full 45° is set, again with strong nose pitch up. In the manual, there only the AUTO mode function depicted, but behavior of HALF and FULL flaps from my perspective should be more linear, which will also help with sudden pitch up attitudes. May be real pilots or crew can help here. Edited June 15, 2018 by GumidekCZ

[Pikey]

Just relying on the passage you quoted, nowhere does it say the flaps come up or down slowly or in increments. What speed they drop or raise in, isn't suggested or even touched upon (in that section), just that it "happens".

[majapahit]

Just relying on the passage you quoted, nowhere does it say the flaps come up or down slowly or in increments. What speed they drop or raise in, isn't suggested or even touched upon (in that section), just that it "happens".

 

Its the massive pitch movement which is awkward

[=4c=Nikola]

You can set gain switch to override if you don't like flaps moving automatically.

[SCU]

Its the massive pitch movement which is awkward

I thought that was fixed in the last patch. As for a pitch up moment on flaps full, real former Hornet pilots like IvanK & neofightr (A.E. W in a video) have said that it's true to life behaviour:

The real aircraft has a slight "balloon" as the flaps start to run. A small check forward on the stick is all that is required to hold the VV on the horizon very shortly thereafter as the deceleration starts increasing back pressure (and increasing pitch attitude) is required to hold the VV on the horizon. It is at this time that the "urge" to trim is felt by the pilot. About 3-4 seconds of back trim is all that is required. In later software loads a Trim value is displayed in the HUD as you trim it remains displayed for 2 seconds after you let the trim switch go. (this is post Lot20 aircraft I believe).

[26-J39]

Trailing edge flaps come down as a function of airspeed and from my tests this works fine in DCS. Flap movement is linear in ranges from 230 down to 195knots where you will get full 30deg flaps in HALF for example.

[majapahit]

I thought that was fixed in the last patch. As for a pitch up moment on flaps full, real former Hornet pilots like IvanK & neofightr (A.E. W in a video) have said that it's true to life behaviour:

 

" ... and its a whole lot better than pre the last patch .."

 

which is a relative opinion, wherein lies a certain relative value,

 

it's still awkward.

[GumidekCZ]

This plane is drived by computer, not hydraulics,.... so there is no point in sudden FLAP angle reposition. Will only make pilot work harder. AUTO mode is acording to F/A-18C manual - LINEAR, I think. So why not HALF or FULL. Last patch helped allot, and I know that real plane has slight pitch-up attitude when flaps came down.