Realism?

[greybeard_52]

Good morning and Merry Christmas to everyone!
I've been flying XPlane 11 for a short time, but two things immediately struck me: the lack of a rudder trim and the marked tendency to pitch up every time you lower the flaps one notch.
I believe that a realistic flight model should have (as much as possible) the same things that a real plane has, and since real planes have rudder trim, the simulator should have it too. Its lack makes me doubt the realism.
As for flaps, my real flight experience is limited to some ULMs, none of which were equipped with flaps, so I have no direct experience of their real effect, but in none of the flight simulators I've played so far have I noticed such a powerful change of attitude with their activation.
I'd like to know what the more experienced think.

[tanawat8814]

I'm not a pilot IRL but have 'flown' a number of models in the sim. Many planes in XP do have rudder trim, but some like the Cessna 172 do not, reflecting the real life airplane, which instead has mechanical trim tabs that are set once on the ground. Typically, these would be set to have the aircraft in trim once in the cruise, I believe.

The pitch up moment when deploying flaps is realistic, based on reports from a number of real world pilot who use the sim.

[greybeard_52]

Originally posted by tanawat8814:

Many planes in XP do have rudder trim

Sorry for my ignorance: I've a Saitek X52 and simply overlooked that its throttle setting in game do have a drop down menu including "Rudder trim". Thank you so much. Next time I'll try to be better informed before asking.

mechanical trim tabs that are set once on the ground. Typically, these would be set to have the aircraft in trim once in the cruise, I believe.

Your guess is correct.

The pitch up moment when deploying flaps is realistic, based on reports from a number of real world pilot who use the sim.

Please let me have still some mental reservation: even IL-2 1946 had an unidentified "group of aerobatic pilots" who claimed that it had "the best flight model".
From a brief search I just did on the internet, the answer that convinces me the most is the following:
"When lowering the flaps, not all aircraft react in the same way...
In itself, the moment produced by the extraction of the flap is strongly pitching, but in reality the effects must be evaluated on the aircraft as a whole...
In fact, the extraction of the flaps produces a notable downwash that can affect the tailplanes, increasing their deporting effect, so much so as to make the aircraft pitch up.
The resistance produced by the flaps also has its effects and for example on a low-wing aircraft it gives a non-negligible pitching contribution.
In essence, there are aircraft that react by pitching up and others by pitching down and still others that do not have appreciable reactions around the pitch axis."

For now I have only tried the Cessna 172 which has a marked tendency to climb when extending the flaps. With other aircraft I could find different behaviors.

[Antaiir]

When you extend the flaps, you gain lift.
When you gain lift, the aircraft climbs.

Seems conclusive to me. :-)

[greybeard_52]

Originally posted by Antaiir:

When you extend the flaps, you gain lift.
When you gain lift, the aircraft climbs.

Seems conclusive to me. :-)

Of course! But I was speaking of attitude: Cessna 172 pitchs up markedly, in a way I never saw even when modeled by Microsoft in Flight Simulator 4 and 5 that I played many years ago. I'm not stating that it is wrong: it just let me puzzled. Maybe XPlane is more accurate and depicts real behaviour, like actual pilots say... As a modest ex-pilot of ULMs, I would only say that for a basic plane as Cessna 172 is I would dislike such a behaviour since would take me by surprise in such a delicate moment like landing.