Posts by jcomm

Quote from bbrz

AFAIK MSFS doesn't use a stabilizer trim system for planes that are supposed to have only elevator trim.

It moves the CG and/or the aerodynamic center forward and backward.

From the MSFS Aerodynamics Reference DOC -Source AVSIM ( by Yves Guillaume ), linked from: https://www.aero.sors.fr/fsairfile.html

This was long confirmed to me by a good source, and by Ron Freimuth, with whom I had the honour to learn a lot about the MSFS internals....

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4.1 Elevator and Pitch Trim

The main pitch control system in MSFS consists of an elevator and a stabilizer trim surface. The pitch trim concept is basically more the one of a moving horizontal stabilizer than that of an elevator with trim tabs. However, the additional lift and drag generated by the deflected stabilizer is not simulated in MSFS. Furthermore, the default autopilot only uses the stabilizer for trim and not the elevator. For consistency with the SDK the term Cm_detr is used although the elevator is not directly involved in trim.

MS seems to have pitch controls designed for joysticks where the stick returns to a fixed center when hand force is released (such as most game sticks, e.g. Saitek X52). Zero hand force means zero elevator deflection in relation to stabilizer, so the stabilizer is the only trim surface.

There are three components related to elevator and stabilizer trim: Stabilizer, elevator and an additional elevator effect due to stabilizer deflection.[...]

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P.S.: Sorry for the out-of-context message - this is an AEFS2 Forum... I know :-/

@bbrz: it's MSFS that uses a stabilator-like modelling of pitch trim. In that simulator, when you trim in pitch, indeed the simulator assumes the whole HS moves, as if every aircraft was just like a typical airliner and most gliders, in terms of pitch trim.

I'll check it in a couple of minutes, by displaying the controller reference axis in DCS, and will report back... Well, depending on PC slot available - wife on finals for Facebook....

Ah! And just as a reference, this is the thread started by the main FDM developer at ED when they were still working on the Spitfire IX - worth reading, and starts exactly with the same remarks you've made Jan:

https://forums.eagle.ru/showthread.php…t=flap+pitching

Further to these interesting suggestions / ideas we're sharing here, I'd say tha Yo-Yo gave the DCS user community the decision between implementing the effect of deflecting the flaps in the Spitfire: stick fixed or moving...

For stick fixed, there should actually be a slight pitching up tendency, as it happens in IL-2 Battle of Staingrad, while in DCS as the flaps are lowered we can see the virtual stick moving fwd, and users with a FF joystick will see it also deflect fwd.

The V-Pilot then has to pull the stick to counter the resulting pitching down moment.

This appears to me as a better solution, even for non-FF joysticks, because it agrees with the Real World effect. All pilot notes for the Spitfire report the pitching down tendency, and a need to increase the force on the stick to avoid it. In IL-2, for instance, since there is no virtual stick deflection, the end result is actually a slight pitching up...

Quote from bbrz

And again (at least) one of my posts has vanished. Sorry guys, that's not acceptable anymore. I'm finally out of here.

Bye.

???

@bbrz, do you, by any chance, mean --> this one <-- ?

Because if it's the one, you answered at a different thread...

Yes I know it isn't the only factor...

Because i do not have AEFS2 installed right now - problems with a very small SSD.... Working on it...

Is the effect of downwash angle variation affecting control surfaces in the tail ( namely the elevator ), on non FBW aircraft, modeled in AEFS2 - or possible to be modeled ?

This applies, for instance to aircraft where the effect of lowering the flaps changes the AoA of the tail dramatically, and can even exert a force in the elevator that the pilot has to counter, because otherwise the sitck will move in the cockpit - ahed, in the case of a Spitfire for instance, causing the pitching down ...

I know AEFS2 calculates downwash variations, but, could or is this already modeled ?

Very evident for instance in the way different sims model, for instance, the pitching moments due to flap deflection in a Spitfire...

The real aircraft pitches down because the downwash in the HS and elevator causes a sudden decrease in their relative AoA, and hence a reduction in their lift and pitching moment, and the elevator actually moves fwd in the cockpit, the pilot having to pull it back to counter the pitch down...

You can actually see it all correctly simulated for instance in DCS World, but not in IL2, or many of the models available for X-plane or MSFS and derivates...

In AEFS2 I believe it can be realistic since the engine actually calculates downwash deflection on-the-fly...

We have to get a Spitfire in AEFS2

I'm glad it's written in German... this way I don't even have to bother with reading any rubbish....

AEFS2 is moving, in a very sound and promising way, in the right direction. Being based on a very small team has it disadvantages for us impatient users, but also the big advantage of not suffering from the same budget constraints of having a lot of developers behind it.

People should really give the Q-400 a good try. Even those features that we could not test with the previous ME prop aircraft now highlight the quality of the flight dynamics possible with AEFS2. Fail an engine in the Q-400 and experiment that kind of emergency. Turn off the Yaw Damper ( which I believe is actually being modelled )...

Promising and already more than worth the have!

Quote from bbrz

Talking about friction related problems. Brakes on basically all planes are unable to keep the plane static with more than 25% power applied.

That has already been acknowledged as well by IPACS, and they say they will fix it in one of the upcoming updates.

Great!

Thx for yours answers. Looking forward fro revised coefficients

1) On all airliners, break away thrust is excessive. I believe even a 60t GW A320 would require just an initial thrust "help" and then keep going at ground idle, unless steep taxiways are used.

This doesn't appear to affect the prop aircraft. I believe the Q-400 though, probably because it's thrust is actually also based on a turbine engine, suffers from the same problem ?

2) All aircraft in AEFS2 are extremely sensible to even the slightest cross wind components, on ground, while taxiing or taking off / landing.

I believe this is now more evident, probably because the developers have decreased the amount of drag effect on wind near ground that was, in the initial release, providing very "faint" winds

on ground even when higher values were set in the "Conditions" menu ( ? ), but while it is good to be able to experience a 5, 6... 15 knot wind blowing while we're taxiing, I don't find it very

realistic that my C172, or even my C90 or the Q-400, weathercock under a quarterly 6 knot ? Since some of the developers have real flight experience, they certainly have the required feedback,

so, I wonder why the modelling in AEFS2 is still so sensible ? Would like to read any comments on this from the Dev team, and, I can't really avoid to compare the overdone effect with what we

also get in X-plane 11...

Autolands in the new Airbuses are usually quite rought. I guess as "soft" as 200fpm can easily happen ( ? ), and that can be a pita for the pax

But the Moon is there, in the right place for the present date

Only the phase is out -of - sync... Always full or new in AEFS2

That's because you were never landed by Sabrina!

My other civilian sim is Aerowinx PSX, the 747-400 flight simulator.

There have long been bridges between PSX and both MSFS / P3d and X-Plane ( example using X-Plane 11 ). These allow for users with multiple displays and PCs, or even with a single PC and display, to run PSX and use the other sim platform to render the World, feeding it with positional data, and using a Boeing 747 cockpit / external 3d model from the "visualization sim"...

I wonder if this would be possible using AEFS2 ?

.) Could it be done using a single display, by assigning half of the screen to run AEFS2 in windowed mode ? Or would we have to use a separate display for AEFS2 ?

.) Is AEFS2 ready to have it's positional variables injected / written by another application, on the same PC or through a network ?

Using AEFS2 for display would be great, given it's smoothness and graphical quality.

It's mostly yaw-induced roll, in the Q-400, if one does not correct the sideslip... and very far from what we had in XP when Austin decided to finally introduce torque effects along XP9... ( well, I had thought they were already modelled by that time, just as the propwsh effects he's now fine tuning for 11.10... it is certainly not as bad as the torque bug in XP... ).

It looks plausible to me the way it is, and AEFS2 can be fine tuned regarding the propwash effects, even on the fuselage, so, I believe we can end up we very satisfactory models...

This is actually very well modeled IMO.

All "torque" effects - engine/prop torque, p-factor ( not so important in the Q-400, unless at a high AoA (+ or -), or in sideslips ) and spiraling slipstream effects are all responsible for this "turning tendendencies".

The real Q-400 requires rudder trim to be set before takeoff, and during every high power / high AoA or power reduction ( for descent ).

It Works very plausibly in AEFS2.

Another good effect is asymmetric thrust, which we can model in the Q-400 by assigning diferente keys / axis to the two "condition levers" and then using it to kill one of the engines and fight the resulting asymmetric thrust, even if the prop is auto-feather.

All aircraft are very sensible to wind on ground, reminding me a lot of X-Plane...

The Extra 300 even slides sideways if you align it with the rw centreline using rudder. Looking from an outside view you'll be able o see it sliding sideways.

Tested with some other aircraft, and while they are very sensible even at a quarterly 5 to 6 knot wind, they didn't slide sideways... Probably a "bug" in the Extra contacts model ?

bbrz, and others who may qualify

I have a question for you

I am a glider pilot, for decades... Some of my fellow glider pilots are actually Airbus captains, and in 1980 got their glider licenses with me...

I keep asking them about the feel of some simulations and add-ons, and have had myself the chance for 2 Full Flightsim sessions, one of them lasting more than 1 hr! at Air Portugal training Centre.

I have used pretty much every flight simulator you can name ( pc-based ) and airbus add-ons, but none ever gave me the feel of true inertia that the real Airbuses ( A320 since that's the one simulated in the Thales and the Sutherland full LevelD flightsims I tried ) and flying in the jumpseats of various A319 / 20 /21s provided me with... well, none gave me a closer to reality sensation as the IPACS A320 provides.

Since I believe you have hands-on real life experience on the type, I would really like to get your feedback here.