CRJ owners, can you please repeat this flight test (static and dynamic longitudinal stability)

[GoranM 3,762]

how can the flight model be bad?

 

from the x-plane web site fairy tales:

 

"The most advanced flight simulator in the world."

 

and ...

 

"I’m speechless! There are absolutely no words that can describe the beauty in X-Plane 10. I’m an avid flight simmer and current student pilot. X-Plane 10 is the closest to reality that I’ve experienced."

 

why quote aerodynamics engineers or FAA examiners when you can quote inexperienced student pilots instead :Party:

 

Yet again, your intelligence and expertise shines through.

[Murmur 3,941]

fly_like_a_troll

[60North 120]

What happened to the CRj on my system? After i pitched up (50% elevator) and released the elevator quickly the plane entered a large amplitude phugoid with a VSI of +1.9K FPS. The plane climed to 12,200 ft after the peak of the phugoid the VSI read -2.2K FPM and it started a descent. It settled down at 11,550 ft after which it started to climb again at about 2.0K FPM the first cycle took about 37 seconds. The plane was still oscillating after 6.00 minutes!!! with about half amplitude and half the vertical speed (1.1K) not even close to being damped out. I shut down X-Plane before it could ever return to straight and level flight - waste of time to wait more...

 

From what I can tell (IXEG 737) the short period damping in XP is is right on the money. about 2-3 oscillations in a couple of sec.

(No use of artificial stability).

 

M

[carrotroot 77]

Getting the steady state portion of a flight model is not good enough. It's 2012 and i think the user expects more

 

Honestly I think *most* users actually just want a pretty looking plane that has a lot of buttons that they can push and nice scenery.

[60North 120]

http://www.xplanefre...n/MOV/pitch.mp4

 

M

[Alec 370]

I know this is an old topic, but one that I find to be very important to showcase the obvious flaws still present in X-Plane FM. Not in a bad way, but to let us go to LR and ask for changes for the better. I wonder if today's X-Plane Beta still demonstrate this kind of behavior, I tried with the default aircraft, and they did, but obviously I can't test with addons since I don't own them.

 

MortenM has shown his addon doesn't fail in this test, so that's a proof that it's possible to have it modeled accurate in X-Plane. My PMDG 737NGX was very stable, I don't know if the aircraft is supposed to return to level flight after this, it didn't, but it didn't start going like a roller coaster either.

 

Again, not trying to bash X-Plane, just want to make it visible for the newer X-Plane users so that we can have it fixed in the near future!

[GoranM 3,762]

Alec

With regards to this...there is nothing to fix. I promise you. All the tools are there in Planemaker. The autopilot is extremely customizable (I just spent 2 weeks making sure the autopilot on my latest project works correctly without the bobbing up and down or chasing the heading marker), so to tell Laminar Research to fix it, would be like telling them to add/fix what is already there.

[Alec 370]

Actually you're right, there's nothing to do with LR here, since MortenM has already proved he successfully designed a FM that doesn't fail the stability test. It's another of those "default aircraft that aren't made for serious flying" examples.

 

And about the autopilot, it's very important that hand flying the aircraft also demonstrate a stable and predictable flight, or we end up chasing the needles like crazy! I Wish I knew more about this, maybe I will start reading some serious material about how these factors have to be taken into consideration by the airplane manufacturers and how they do their testing. Now that I'm flying in real life I can clearly see why it's so important to be flying a stable airplane, you as a pilot just isn't able to focus all the time on the flight, there's so much to do up there, the aircraft must do some work on it's own!

[jcomm 5,890]

Alex,

 

I can only reinforce Goran's reply... X-Plane is becoming a huge positive surprise to me each time I try to explore it's multiple features, Plane-Maker being one of them...

 

It's a shame, but certainly not unique to X-Plane, that many nice looking aircraft have nothing to do with being nice-looking when it comes to replicating as plausibly as possible in a PC-based simulation platform, their RL counterparts. Sometimes we download "excellent" models, in any sim, but unfortunately most fall short from even having been designed with the use of RL data extracted from a simple POH...

[Alec 370]

Let's hope more developers acknowledge these issues and start doing these kind of tests before releasing an addon. It's so important! If it were a car sim people would complain that they're starting a turn and the car starts to oversteer every time unless they turn the wheel in the other direction. Actually some cars may be setup for this, but it's a very specific condition, not one you would want to have on your daily basis driving around town.