CAS Seems Not Modelled?

[Avio]

I switched off all 3 CAS switches to test the result, but controls seemed to be fine as usual with no noticeable degradation. Shouldn't there be an effect with no CAS in action?

 

[Thx1137]

I'd have thought so but as a guess, they probably put more emphasis on developing the ability to fight using a normally setup aircraft. 

I wonder if they would have to a new flight model for every possible switch combination. That would be an obscene amount of work.

[Avio]

That brings to mind, how in-depth is the overall systems modelling in this F15E ? I was / am hoping it would be developed to the same extent as that of other DCS jets like the A10C, etc.

 

[Rainmaker]

5 hours ago, Avio said:

I switched off all 3 CAS switches to test the result, but controls seemed to be fine as usual with no noticeable degradation. Shouldn't there be an effect with no CAS in action?

 

You are looking at something that you dont know what you are looking at. Its modeled. 

[Ramsay]

6 hours ago, Avio said:

I switched off all 3 CAS switches to test the result, but controls seemed to be fine as usual with no noticeable degradation. Shouldn't there be an effect with no CAS in action?

TL;DR:

CAS = ON is for normal flight, CAS = OFF is a fall-back mode.

IIRC CAS trims for 1G and damps pitch oscillations among other things, on initial release the DCS F-15E showed some undesirable pitch oscillations after take off and CAS was tuned to behave in a better (more realistic) way.

My understanding is that CAS is why the F-15E has "fly by wire" like flight and doesn't require lots of trim adjustment.

AFAIK, turning off CAS is most noticeable by the amount addition trim adjustments needed to maintain level flight, etc. at different speeds/altitudes but I haven't tested this in DCS.

Before the CAS fix, users reported that CAS=OFF helped fix the undesired pitch oscillations -  so it would seem that the CAS reversion/ fall back mode used to work.

1 hour ago, Avio said:

I was / am hoping it would be developed to the same extent as that of other DCS jets like the A10C, etc

It is (if not more so), as explained, AFAIK the DCS F-15E CAS control logic was partly responsible for causing pitch oscillations after take off and required tuning.

Flight model/system tuning during early access is an iterative process and to be expected.

Detail:

Quote

Why is CAS desirable?

.... the F-15 airframe is basically stable, and the manual flight controls are designed to give Level II handling without augmentation.

Despite the basic stability of the Eagle, various flight conditions and varieties of store loadings can result in some pretty touchy handling situations were it not for the CAS.

In addition, the CAS provides safe control of the aircraft should the basic mechanical system suffer failure or battle damage such as foreign object jams or shot-away linkage.

https://www.f15sim.com/operation/f15_yaw_control.html

Edited August 27, 2023 by Ramsay

[Avio]

Thanks for the link Ramsay, that’s a good article.

The Yaw CAS for example is to dampen out unwanted yaw as shown in the article. Having switched off all 3 CAS the plane flew quite normally still. Will try out other flight regimes to see if it makes any difference.

 

[Eaglewings]

CAS may not be significantly apparent in SE like in true fly-by-wire F-18C but I reckon should be on to use autopilot feature in the jet. .

Sent from my XQ-AT52 using Tapatalk

[MagicSlave]

I tried a simple test: Starting at about 17000 ft MSL (15K ft AGL), about 340 KIAS, MIL power. Pull the jet vertical and keep the nose pointed straight up as the jet decelerates for as long as you can. Let her stall and see how she recovers. First with all CAS ON and then all OFF.

The jet feels whole lot more stable with CAS on, almost FBW-like. Holds nose pointed very well, then nose drops when speed is at 20 or so knots. Recovers very smoothly when let go of the stick.

Then with all CAS OFF: feels very different, have to use stick and rudders whole lot more to keep nose pointed straight. If you keep her vertical while speed bleeds off, she starts to slide backwards, tail first. Nasty stall and spin. Had to use opposite stick and rudder and gentle touch to get her out of it.

Kinda same differences when turning, pulling lot of AOA at 200-300 KIAS. Try it yourself, I think that the CAS ON/OFF is definitely modeled.

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[Avio]

Thanks for the doing those tests, glad the CAS is modelled in here. Will try those tests out when I get the time.

[draconus]

By the manual only the CAS warning displays and terrain following coupling are not yet modeled.