cannot reproduce F-5E flight model

[Sierra1]

Hi,

There are some annoying properties of the F-5E flight model.

1. Roll damping. The roll damping is way too low at all speeds. I have compared to other airplanes I fly IRL and there is something very wrong. If I set up a roll speed (roll angular velocity), the airplane stops rolling after some time after I neutralize the stick. IRL planes stops rolling almost immediately. Otherwise they would be unsuitable for a real pilot. There are several other planes with the same behaviour in DCS.
   Someone from DCS, pls comment on this.
2. Speeds. The F-5E with some external load (tanks for instance) will not exceed 300 (or so) knots on military power. Is this correct? The older F-86 is way faster.
3. I cannot aerobrake after landing, the nosewheel drops whatever I do. I have seen aerobraking on the F-5A IRL here in Norway. Why is this impossible in DCS?

Best Regards
Sture Smidt
M.Sc. Aeronautics
PPL/A holder (1000h or so)
Compete in aerobatic competitions on the Advanced IAC and CIVA level.

[nairb121]

1. I was able to find data on roll response for an F-5A, which should be similar enough aerodynamically for direct comparison, in the public release document at https://apps.dtic.mil/sti/tr/pdf/AD0738625.pdf . However, this is mostly concerned with roll initiation rather than damping, though there were a few references to the F-5A having strong roll damping. Were you testing this with a clean aircraft, or carrying wingtip/pylon stores? Particularly with how light the F-5 is, and how thin its wings are, its roll inertia is extremely sensitive to outboard stores - per the document linked, the roll mode time constant can increase by over 4 times from a clean aircraft to fully loaded. It's possible that the DCS F-5E is overly sensitive to wingtip missiles - I think this has also been discussed elsewhere.
2. It should still be capable of Mach 0.8 or higher with most loads, but with a heavy/high drag load the AOA required to get airborne can make it difficult to accelerate to cruise speed in MIL - if you use afterburner to accelerate to 400 or so can you maintain it in MIL? Also, if you took off from a cold start make sure you're retracting the airbrake.
3. This will depend on CG location - if you're carrying centerline stores the F-5 can't hold its nose up with much weight on the wheels, but with a more moderate CG, you should be able to aerobrake with a good flare and a gentle touchdown - as long as the nose doesn't come down you should be able to hold it up for a little while.

Edited August 7, 2024 by nairb121

[=475FG= Dawger]

 

[NineLine]

On 8/7/2024 at 1:49 AM, Sierra1 said:

Hi,

There are some annoying properties of the F-5E flight model.

1. Roll damping. The roll damping is way too low at all speeds. I have compared to other airplanes I fly IRL and there is something very wrong. If I set up a roll speed (roll angular velocity), the airplane stops rolling after some time after I neutralize the stick. IRL planes stops rolling almost immediately. Otherwise they would be unsuitable for a real pilot. There are several other planes with the same behaviour in DCS.
   Someone from DCS, pls comment on this.
2. Speeds. The F-5E with some external load (tanks for instance) will not exceed 300 (or so) knots on military power. Is this correct? The older F-86 is way faster.
3. I cannot aerobrake after landing, the nosewheel drops whatever I do. I have seen aerobraking on the F-5A IRL here in Norway. Why is this impossible in DCS?

Best Regards
Sture Smidt
M.Sc. Aeronautics
PPL/A holder (1000h or so)
Compete in aerobatic competitions on the Advanced IAC and CIVA level.

1. While we are still missing the Artifical Feel system, I am not sure a comparison with other aircraft is enough to enact any change. If you have anymore actual references we can look into it.

2. I cannot reproduce

3. I cannot reproduce, feel free to include a track with your experience though. 

Thanks!