fixed Nose suck down effect when Landing

[Swift.]

This is an attempt to capture in a bug report the as yet unfixed facet of the reverse ground effect bug, whereby the nose of the aircraft is 'sucked' into the ground when landing.

DCS

In DCS, 2 approaches were made in Half and Full flaps, both trimmed to OnSpeed using the E bracket and both flown as hands off as possible.
Approaches were made at an airfield to allow minimal control input.

Refer to tracks: Fullflap.trk and halfflap.trk
It is observable that the AOA, shortly before touchdown, will reduce enough for the AOA indexer and the E-Bracket to be showing a 'Fast' landing.

Here is a clip of a carrier landing where this effect is displayed, more control input is made, but it is noticed that the lack of pitch input does not correlate to the lack of AOA movement.

 

Real World

See this clip of an FA-18C landing on the carrier, notice how the E Bracket stays relatively steady compared to the DCS examples.

Supplementary to this, here is a clip showing an FA-18E landing on a carrier, also showing a steady E-Bracket, however this time it is also visible that the pilot is not inputting a back force on the stick (along with a reduction in power) as would be required in DCS to achieve this behaviour.

 

Abstract

In an attempt to further understand this behaviour, I attempt 2 low approaches with the gear up and flaps in Full. On the first pass (notrim), no trim was applied after flaps were dropped, leading to an already 'Fast' approach. A significant reduction of this nose down effect was observed.

On the second pass (trim) the jet was trimmed to 8.2 AOA prior to the approach, in this example reductions to ~7 AOA can be observed.

The conclusion I draw from this is that the effect appears to be attempting to nullify the trim applied to the jet, which is why it is not seen for the 'notrim' track.

halfflap.trk Fullflap.trk notrim.trk trim.trk

[Ahmed]

There is definitely some odd behavior either on the FM or FCS. I hope this is being investigated for the FM update.

[BIGNEWY]

 

We do already have a report open to look into this. 

thanks 

[GumidekCZ]

See the last 5 seconds before touch down and watch the "W" mark on HUD and AoA bracket.

DCS Open beta 2.7.8.16140 and its ground effect bug, causing roughly 3 degree decrease in pitch.

This nad behaviour is also present above carrier deck, causing unwated drop into wires with low AoA, many times graded by carrier LSO by "Landed on all three wheels" aka "3PTS-IW".

Edited November 30, 2021 by GumidekCZ

[BIGNEWY]

Merged threads, this is already reported

thanks