FishBike

Yup, I hit about M2.15 today at just about 37,000 feet, clean.

As luck would have it, I just finished running through the cold start process again trying to learn it. A momentary push on the T/O trim button is all it takes.

What I'm saying is the yaw moment DOES go to zero when the rudder is centered. And because you have a 1-2 degree per second yaw rate, that rate will continue until a yaw moment in the opposite direction makes it stop. In the air that yaw moment happens due to sideslip, but on the ground there is hardly any sideslip. The main gear would contribute some yaw moment to reduce yaw rate, but they are very close to the center of gravity, so may not do that much.

That sounds kind of right to me, actually. The plane should have a moment of inertia in the yaw axis, so once you get any kind of yaw rate happening, it should want to keep on happening until some moment in the opposite direction stops it. In the air, if you get some yaw going with the rudder and then release it, you have quite a bit of sideslip, which results in an aerodynamic force on the vertical stabilizer that tends to point the nose back into the relative wind. On the ground, with the main gear on the runway, you don't get nearly as much sideslip happening and so there's not much of a side load on the vertical stabilizer when you let off the rudder again. So unless the flight control system deliberately puts in some opposite rudder momentarily to stop the yaw rate, I think it would continue for a little bit after you center the rudder.

In the original 1.5.3 update 3 I couldn't even stay in formation with the tanker. After yesterday's update it is MUCH better and I think only the constant but slow pitching up was really throwing me off. It does seem you can counteract that somewhat with some pitch trim. How are other folks finding it after yesterday's update?

Just re-tested this after today's update, and it looks great now. Yay! :)

I just re-tested with today's update. Pitch control in general is much better now, the flightpath stays pretty much where you put it once you release the controls rather than taking 3-4 seconds to settle down like it did in the previous update. However the slow pitch up problem seems to be there still, especially in a gentle turn. :(

Real planes often have a switch in the main landing gear that detects when the plane's weight is on its wheels. It's used as a signal to a bunch of systems to indicate "are we on the ground, or are we in the air?" I have no idea if RAZBAM has implemented it that way in the flight model, but it seemed the easiest way to describe what the bug looks like. Sorry for any confusion!

RAZBAM continues to be awesome in responding to these kinds of things. :)

Just noticed in the latest update that the switch detecting when the gear is on the ground seems to be hooked up to the nose gear instead of the main gear. One result is the inverted T symbol on the HUD, that is supposed to tell you how far it's safe to pitch up during takeoff and landing, disappears as soon as the nose wheel is off the ground during takeoff, and doesn't reappear until the nosewheel is back on the ground at landing. Making this feature not too useful. :)

I did some slightly more formal testing this morning. The good news it is seems really easy to reproduce this behavior: DCS Version: 1.5.3.51870 Controls: checked that only one controller was bound to the pitch axis. Set a large deadzone (10) to ensure there was no pitch control input when the stick is centered. 1. Create a new mission file. Leave weather set at defaults (20 deg. C, QNH 760, wind 0 m/s). 2. Place M-2000C at Batumi, with waypoint type "takeoff from runway". Loadout: "empty", 100% internal fuel, 112 chaff, 16 flare, 100% gun (all defaults). Total weight=24,046 lbs. (Yesterday I was flying with a single external fuel tank and saw the same thing, though). 3. Save mission file and then run it from the "mission" menu. 4. Take off in full afterburner, raise gear, establish climb attitude, and then release the stick. 5. After a few seconds, the plane begins to slowly pitch up. (Ignore the TVV/FPM, look at the pitch ladder bars on the HUD). Leaving the throttle in full afterburner, the pitch up continues as the plane accelerates through 500 knots, and does not stop as it loses speed in the climb. I got to 53,000 feet and 160 knots and it was still happening. 6. Turn around and return to Batumi, descending at idle thrust and 350-400 knots. Same slow pitch-up continues. It seems to happen a bit faster in gentle turns (15-30 degrees bank angle) but pitches down in steeper turns (as expected). 7. Fly around Batumi at 5,000 feet maintaining 350 knots exactly. Same slow pitch-up behaviour continues. All of this was with the mode switch set to A/A, but I had it set to A/G yesterday and saw the same thing.

Sure thing, I will do some more testing and see if I can give you some useful details about then this does and does not happen.

Just wondering if anyone else has noticed that pitch attitude is not stable in the Mirage as of DCS 1.5.3 Update 3? The big problem where it would constantly pitch up, especially at lower speeds, seems to be fixed. But what I am seeing now is after getting it to fly level, it will slowly pitch up or down. I can use pitch trim to get it stable again for a little while, but it doesn't stay that way, and I didn't think we were supposed to need to trim the Mirage much anyway. It doesn't feel like the normal change in pitch trim with airspeed that we get in non-FBW aircraft either (e.g. it'll keep pitching up as speed decreases). It also seems like it takes a lot longer before vertical speed stabilizes after a small pitch attitude change, like 3-4 seconds. This was particularly noticeable during air-to-air refuelling. I know there have been a lot of improvements to the flight model lately, so maybe these effects are intended. Just wondering if anyone else has noticed them, and whether they are supposed to be happening?

While doing some landing practice today, I noticed that at exactly 6.0 degrees angle of attack, the slats repeatedly deploy and retract. This was at around 250 knots in level flight, though it happened at progressively lower speeds as I used up fuel. To reproduce the issue, slow down until your alpha reads 5.9 and then continue a gradual speed reduction. As your alpha passes through 6.0, watch the leading edge of the wings and you'll see the slats shaking up and down. It stops before alpha reads 6.1. Speeding up through the problem airspeed also shows the issue. I'm pretty sure that's not supposed to happen!

I noticed this happens if I've left the ignition/vent switch in one of the on positions. If I turned that off after shutdown, everything else goes off like it should.