Remodeling the flight model

[Pyro]

We have been going through the flight engine over the past couple of weeks.  The changes have been piling up with one change leading to others.  So far, we’re pretty pleased with the results but it does require extensive work.  The changes we’ve made result in a more accurate model and we’ve also implemented better methods and tools to verify accuracy.  

One of the major changes we’ve made is how we model the forces on the plane.  We wanted to increase the number of force points by about an order of magnitude or even more if necessary.  For example, prior to this the wing was split up in large chunks with the applicable forces applied to each chunk.  In level steady flight this is fine, but it shows its limitations when you get outside of it.  Now we have it split up into a lot of small pieces.  This allows us to closely replicate the stall progression characteristics of the different planes.  It’s also led us to some oversights in the model.  An example of this is the effects on the propeller vortex on the wings.  We’re modeling the forces of the vortex and its effect, but we weren’t applying it exactly where it needed to be applied, thereby creating an inaccurate force moment.

We’ve also discovered some processes that I used to check model accuracy that weren’t exact.  I would calculate stall speeds to check that the model inputs were having the desired output but I did not account for tailplane forces and some other influences which would throw my calculation off some.  F4UDOA was very helpful in documenting and quantifying this particular problem.

We’ve taken a pretty fresh look at the model mechanics and are going through the process of identifying inaccuracies and their causes and making appropriate changes.  So this is a tremendous amount of revision along with some additions such as working slats.  This does mean that every plane will be reworked.  The change to a particular plane in 2.0 might be minor or major.  There’s really no telling until we work through everything.  We made a huge change to our drag model early on in AH that had a profound effect on the game.  That was a very large error and we’re not really talking about a global change on that level.  This is really just a big refinement to get things as accurate as we can and to also try and capture the nuances of the individual planes better.

Feel free to bring up any particular quirks in the flight modeling that you would like me to look into.  Please present your thoughts in a cogent manner.

[acepilot2]

WOW!!! NEWS!!! KEEP IT ROLLING!!!! THANK YOU!!! NEWS!!!!

[acepilot2]

Seriously though, it sounds great.  This will cause a more technologically complex flight physics engine, making it more realistic.  You have just filled me with some more hype about AH2.

[F4UDOA]

F4UDOA was very helpful in documenting and quantifying this particular problem.

OMG!!

I wish I knew what I said, I would say it again.

I luv when Pyro talks about realism, I get all salamanderly

[bod]

Cool, better flight model

There's one thing that IMO should be upgraded: Engine model and engine sound. As it is now the pitch (of the sound) changes with manifold pressure and not with RPM (on constant speed drives), and the pitch (rpm) - manifold pressure coupling is static. Pitch should oscillate when the governor is acting etc.

Maybe a new engine model with separate sounds for engine and propeller ?

[jEEZY]

I have noticed that the torque effect on take off seems light.  Even a 172 requires more rudder than most of the planes in AH.  Just an observation.

[Seeker]

A purely subjective note:

I don't seem to need as much rudder as I would have thought nessecary. I use rudders more in a glider than I do in these high torque prop planes.

I have absolutly no data to back this up; and I admit to using combat trim.

However turns do seem to be almost auto coordination.

[Duedel]

There are articles that state if u would pull full throttle when starting p.e. a 109 would just flip around. In AH u still will have full control. I would suggest to take a look at some starting procedures and maybe (when necessary) refine the starting.
I ever thought u have to throttle up very very slightly.

[CurtissP-6EHawk]

Now if I could just find an accurately modeled force feedback joystick and rudder peds! For me, auto trim takes out much of the nose bounce but hinders dogfighting, remove the auto trim and dogfighting is non-existant for me. Skuzzy helped me with some settings but I am still unable to dogfight. Even at D300, my nose bounces everywhere but on the con.

I use more rudder in this sim than I do on my 180 Skywagon or any other tailwheel airplane I have ever flown, never ground looped one ... yet..., but I put many many sim fighters out of service in AH do to gear whipe-outs and ground-loops. The sim, IMO, feels nowhere near like the real thing.

BTW, my grandfather watched several P-51s piloted by Korean pilots, roll inverted on take-off and slam into the ground do to full power torque rolls.

[streakeagle]

Thank you for the news. Good info.

Realistic or not, I did enjoy trying to take off in the F4U back in AH 1.03. I would like to take off in a real F4U and P-51 to compare to AH. Robin Olds stated that the P-51 built up a very strong leg from using rudder on takeoff. Is there such a thing a force-feedback rudder pedals yet?

[2Hawks]

Greetings.

Thanks for some news as to whats been going on regarding development!

And now my observations...

It's been noted that all taildraggers depending on weight have a tendency to want to yaw a lot on the ground during takeoffs for reasons not related to thrust or control surfaces.  trying to steer with a heavy tailend attempting to excert it's momentum in the direction opposite that which you would prefer to travel ruined more than one pilots day.

I found maintaining or re-establishing control on the ground was far too simple in some conditions. Also noted was the lack of effect of weight on the tail wheel or nosewheel changing the amount of turn force exerted on the ground.

The plane this is most noted is in the "Ensign Eliminator"- The F4U Corsair. I can tumble a spit in the air a whole lot easier than the F4U, which seems to be a lot more docile in handling high speed stalls and such.

Hopefull the new modeling will reflect this.

What Say Pyro? Will we be seeing new inertial effects as well as aerodynamic effects?

[JB73]

Originally posted by Pyro
Feel free to bring up any particular quirks in the flight modeling that you would like me to look into.  Please present your thoughts in a cogent manner.

the N1k2 is a UFO






sry i had to... :D JK



seriously the bf110g2 has something odd happen and i dont know a ton about real flight but here goes.....

fly level @ least 200 mph on the white needle and do a hard rudder turn while climbing. around the moment of stall apply full opposite rudder and stall out the plane. im pretty sure how i accomplish this... i KNOW i can replicate it at will almost... it's all about the full rudder @ the start of the stall.

what happens is you will go into a 100mph tail first fall... you will literally be going backwards for part of the fall. all stall recovery tactics i have read dont work. the only way i have been able to get out of it is manual trim all the way nose UP and zero throttle, but this still takes about 5000k feet of freefall to recover... if you are below 5k AGL when this happens you will not get out.

just my 2¢ about it.... i may be missing something and this might be a real charertistic of this plane.

[Kweassa]

Thanks for the news Pyro.

 Expectations have now gotten higher

 ps) could we have just one itsy bitsy little teaser pic on the "MTF"?

[Straiga]

I know the Flight Dynamics are being reworked, But I have noticed that when the tail sect (empinage) is shot off the nose pitches up. The center of pressure(lift) moves aft on the main wing the faster the plane goes, the horizontal stab create"s down force for the plane to be in balance. When the tail section is shot off the nose should pitch down not up. Same with flaps when flaps are used the AC should pitch down not up.

I was wandering how accurate the new flight models will be?
A real P-51D can not take off with full power, theres is not enough rudder to counter the torge,P Factor, Prop Slip Stream and Gyroscopic procession. Power has to craduley be increased on takeoff.

In AH aileron is used to counter torge, rudder is the only thing that counters torge. Ailerons on take off have no effect on torge no airflow at 0 airspeed. Aileron trim should be used to balance fuel or ordinance not torge, once set the plane plane should stay lvl at any airspeed.

[Pyro]

One thing that I mentioned with regards to torque is that the propellor slipstream effects on the wings were being placed too far out thus creating an artificially large force moment.  This effect counteracts torque to a degree, an overly large degree in AH until now.  The propwash from a propellor comes off in a vortex that corkscrews back over the airplane.  In a standard clockwise rotating engine, the vortex strikes the right wing with a downward component and the left wing with an upward component.  This increases the effective aoa of the left wing and decreases the effective aoa of the right wing, hence more lift on the left wing and less on the right.

The slipstream continues to corkscrew back to the tailplane where it impacts the vertical stabilizer on the left side which pushes the tail to the right and the nose to the left.  This is the main force causing the left yaw on your takeoff roll.  

With regards to that, the main factor countering that in AH is the modeling of the tailwheel.   All the planes have a steerable tailwheel and that is a change we are looking at as well.