60North

Real FDR data playback of flight ET302 with X-plane. First 2 minutes for now. Based on the real FDR data released in the preliminary report. (So not me flying by hand, this is real data playback)

How an aircraft stalls will vary from type to type and the input from the pilots and weather. Not many have tried this with an airliner, but if you check out the AF447 accident report (A330) and how it went down you will see that it "glided" (wings level) all the way down from cruise in the stall. So I guess again XP has it right if we use that example I can also tell you this is also what happens in the big professional 737 sims I tried M

Murmur is correct. It is also called yaw induced roll. Below a certain airspeed (crossover) on airliners, the rudder will overpower the ailerons. The reason is that at low airspeed maneuvering you need more rudder authority. Like on decrab in crosswind and keeping the aircraft on the centerline on a slippery runway, one engine out scenario, (Vmcg etc). However you do NOT want this at high speeds as it is very dangerous (as you experienced), so to prevent an accidental hard rudder input at high airspeed, airliners use what is called "rudder phaseout". The higher the airspeed, the less rudder deflection you will get if you stamp on the pedal. At low airspeeds, the max rudder deflection on an airliner is around 30 degrees, at cruise it is only a few degrees. But basically the aircraft manufacturer can set the crossover speed to what is necessary and safe. Have a look at this real accident replay by NTSB, USAir 427, the rudder on the 737 went by itself to full deflection, the pilots countered with full aileron+rollspoilers but didn't have a chance... We model this pretty close on our 733, within 2 kts if I recall correct. https://www.youtube.com/watch?v=7CIAXOq9pwI M

More likely the airbus FBW (artificial stability) kicking in

Sure do Robert. Let us know if there is something we can do to help alleviate/speed things up for you porting one of your projects over.

As a long time XP developer, personally I think it was a wise decision by PMDG to hold off any XP11 updates until atleast XP v 11.10. XP 11 has (as usual) been a moving target flight model wise (and other stuff). This is tradition in a new XP run which normally does not stabilize until v xx.1 or xx.2 Especially on the prop/engine side of things (DC6) things have been a work in progress for the past year. Any effort made by PMDG since XP11.0 release would mostly have been a waist of time with a very high risk of work being broken. To me it shows that PMDG sets quality and stability first, and I'm sure they had enough on their plates and better time spent on P3D in this period. Also not to mention this is their first XP project, and an early 11 release could have given them a support nightmare and bad reputation. We now after 11.1 expect things to stabilize (by experience), and XP developers now can get back in the game without a big risk of their work being broken by LR. So we now have a few years of sunshine and peace ahead, and I'm sure PMDG will be a part of it one way or the other - atleast I hope so :) M

Right, on a single engine prop, the left and right side wing will have slightly different aoa depending on if the prop in front of it is moving up or down, so different lift. Also correct, a low wing aircraft will have less dihedral effect than a high wing https://www.dropbox.com/s/o9arneiwo13uvy4/dihedral.jpg

Sounds like you are using an old IXEG version, if so update to v1.2

Jcomm, we have worked with austin on this, documented and reviewed the whole ground effect on all aspects. Pitching moments, lift and drag should all be well inside the ballpark now. This is extremely complicated stuff and affects different types of aircraft differently depending on geometry, configuration etc. So what you experience will vary as in real.

The updated groundeffect made it into b5

If you are experiencing obvious weird behavior - especially in a beta - the first thing you should do is delete the XP prefs files and try again.

We are working with austin on the ground effect pitching moment, at this point it is uncertain if the new model will make it into 11.10

Thats off course up to you, but speaking of the FMS, as you know, the FMS is much more than the FMC, it also consists and depends on several other systems like the AP, and A/T to mention a couple. They all need to interact correct, modes, sensitivity, behavior to be right. Further, and most important maybe, for the whole FMS to be anywhere realistic the flight model needs to be right to get the correct vertical profile ( lift, drag, engine performance etc etc)! So you are on very thin ice already judging how good the FMS is on any sim aircraft unless you have deep knowledge in all these areas which means you need to be an engineer - and - an in type pilot to have anywhere near an objective view of the FMS. (You off course might be, I don't know but it's not common). Sure, but it's in no way objective (which was what I reacted to in your post) it is an opinion ;) M

What IS very misleading is judging an aircraft by just by parts of one system as you do. All aircraft have their strengths and weaknesses. What is important to each user also varies a lot - the list is endless - but to most users it is the overall impression that counts. Should you try to give an "objective" view, you would have investigate in huge detail each system, flight model, 3D, textures, sounds etc etc and then try to sum it up, but it still would be biased since I'm pretty sure you do not have the competence (formal education) needed in all these areas.

Correct, FSX has got it very wrong according to the documentation I've seen. They have mixed up several of the effects, confusing span with chord etc. XP10 is very close, XP11 appears to have some issues, but thats most likely an unintentional bug that will get fixed. Might not even be ground effect related.

This is some bug in XP11, in XP10 it works as it should (I helped LR with it). New XP versions are usually very buggy for quite a while. Austin made big changes to parts of the flight model and probably broke something.

Do you mind explaining what you mean by that?

You are jumping to conclusions. At IXEG we have also been contacted by a couple of simulator companies wondering if we could make aircraft models using "table based" like FSX etc does. In fact since our FM is so accurate, one company assumed we already were using tables....and we off course are not. What these training sim companies usually are after on the flight model side is pitch/power accuracy (AoA/N1/IAS/ALT/Weight) since this is essential to pilot training. This is much easier to achieve with "tables" than with XP's blade element theory. But it is off course indeed possible to do also in XP - as we have proven - if you know what you are doing and have extensive data on your aircraft. The downside of using tables (unless extremely well done like the big level D-sims) is as many have noticed, you loose a lot of the dynamics, fluidness and feel. Also stability (short and long periods etc) is really hard to get right plus a few other things. Regarding this aircraft, I'm not 100% sure what exactly they do, but to me it sounds as if they are using the relatively new option in XP, the ability to ad forces. We use it as well, only very small scale in one or two cases if I recall right. Anyway, this is great news for XP, the more quality aircraft, the better, and I'm sure their flight model will be better than anything FSX/P3D has to offer :) M

Check all XP default failures are off, also that your flap button is not assigned to something else also, like trim..

XP11 will *eventually* have a better flight model, but at this point it is work in progress, buggy, some stuff is broken etc. When stable, quality aircraft need to be recalibrated, so it will take months before everything is back to normal. Stick with v10 for now is my advice

I think many do not understand how big the implications of this activity is for everyone that enjoys X-Plane. The general user thoughts are"who cares if the designer looses a few bucks here and there, it doesn't affect me anyway....right?" Stop a bit, rewind; What are the actual effects of piracy/sharing? 1. The obvious, developers and vendors loose money (who cares) 2. XP is already a small market, pirates make it even smaller. 3. The smaller the market, the less it will attract the big design teams (like PMDG etc) 4. The smaller the market, existing designers will hesitate making more aircraft, too little gain 5. The smaller the market, design teams can not expand, hiring more people to develop 6. Development will go slower, and might affect product quality 7. A smaller market might lead to higher prices of addons to cover development higher unit costs and time. 8. Designers and vendors have to use a big amount of time developing DRM's, time they could have used for developing more add ons and be productive => in other words, XP piracy/sharing ruins and undermines the entire development community, leads to less diversity and, less quality add ons and higher prices. What are the effects of "false reset requests" and "fake news" topics? 9. It puts extra loads on support systems 10. The extra load means longer waiting time for those with legitimate requests 11. Designers and vendors have to spend extra time in social channels, answering/defending accusations. 12. "Fake news" (bad PR) cost money, making the market even smaller. 13. This is very demotivating, and designers might stop developing further. I can tell you IXEG and XA have spent slot of unnecessary time and energy on these things, but what we really want is use our time and energy developing better products for you all. => In other words, "false reset requests" and "fake news" it increases support waiting time, increases development time and might lead to less quality products So, basically these guy's are undermining the hobby we all love big time, for EVERYONE! I'm not even sure they thought about it, but thats how it is. The flightsim community - and especially XP - is small and fragile, we cannot let these idiots continue to destroy it. --- (Just for the record this rant is off course not meant as an excuse for bad customer service that I know some of you have experienced, and we apologize for that) M

Our experience with this is exactly the same as jspahn. As for the IP thing, as far as I know, the security system tracks machine ID so that is not the case. That being said, the reset time/system at the moment is too slow and unnecessary complicated, therefore XA is working on a new system to make life easier for everyone (except pirates) We are also considering a tougher approach on those caught pirating and starting "fake news" topics, and we might also seek closer cooperation with sites like Avsim and .org sharing information to expose these guy's which are costing XP developers and vendors huge sums every year.

According to XA's security systems jandiek has been sharing multiple XA products with atleast one of his friends (identified). XA will always give activations to legitimate requests within reason (why not, they don't cost anything..!). So if someone says XA is refusing them activations, or don't respond to their 50 emails or 20 tickets.... well...... M

You would expect the 757 to have less ground effect (chord dominated ) than say a 737 or MD80. The reason is the long 757 gear. Big portions of the 757 wing will never enter CD ground effect. On the 757 the wing root altitude is at minimum 33% chord alt, vs e.g. the 737CL's 19% (approx). Wing tip even worse... XP handles this ok out of the box, but to get it 100% you need to tune it... M

Nice!