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Where are Fsx formulas?

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italy
Hi to all. Just a stupid question. Where are burried the Fsx formulas that the program uses for flight dynamics? Expecially i'm looking fo helicopter's ones. Thanks!
 
Thanks, i know Flight Dynamics in Msfs document. I thought that several equations displayed there were extrapolated from FSX in some way and compared with real world engineering. But probably not?
 
"Aircraft_Sim_Tech_Zyskowski.pdf" has an overview of the flight dynamics used in FS, but does not include helicopters. For airplanes the standard aerodynamic equations are used together with the individual standard aerodynamic coefficients which are in the air file. Quite how it models helicopters is a bit of a mystery and some designers prefer to use external dynamics software to models the flight characteristics. To further complicate the helo scene, there are three basic types. The original models were based on the Bell, there is also a newer version based on the Robinson and a multi engine version based on the EH-101.
Roy
 
One thing that might help you is to download and install HTR v6.2. Helicopter Total Realism, by Fred Naar. Wonderful program. It runs alongside FSX or P3d and takes the sims output to the helicopter and makes it correct for what helicopters actually do, and the inputs from the helicopter and the user, and makes them something the sim can use.
In other words, it corrects the sims worst failings regards helicopters. Fred is an Aeronautical Engineer, with a Helicopter specialization. He knows his stuff! During his development of HTR, he had inputs from real world helicopter pilots, as well as sim pilots who have specializer in helicopters.
Having babbled about this long enough, I will go on to say that the documentation Fred has written and included with the HTR package is very good. Accurate and complete. He includes the math formulae that both the sim and HTR use. It's mainly written for use in making a custom file to control a specific helicopter by the user, but very informative in general about helicopters.

Just do a google for "Fred Naar HTR" (no quotes) and you will find it. v6.2 is the latest I know of. It works well for FSX, and P3D v3 and below. I don't know at all about P3D v4 and up.

Hope this helps a little...
Pat☺
 
Pat,
I tried that program and it seemed like it grossly exaggerated every bad characteristic of helicopters. I have a lot of helo time in the sim and a couple of real dual flights and HTR was IMHO very unrealistic.
Roy
 
Remember, every system, and thus, every helicopter ON that system, is different. WAY too many variables to take into account to make any two work "correctly" or the same.
That's why Fred (a really great guy, BTW) included all the documentation on how to change the .cfg files. They're not only there for adjusting individual helicopters, they're there to make an individual helicopter work correctly on an individual system.

Once you get the .cfg file, and the HTR settings, zeroed in for that helicopter, on that system, it really is a super add-on. The various RW helicopter pilots, and there have been quite a number involved in the development and testing of it, all say that with HTR, and a properly tuned .cfg file, a helicopter in the sim can be made to fly very nearly like the real thing. Without it, they're not even close, except some, a few, of the higher end payware models. This is according to helicopter pilots, not just "simmers". Even some military pilots. The biggest complaint every real world helicopter pilot I've talked to, is there's no "seat of the pants" input to their brain, as they got used to, and came to rely on, when flying helicopters. Not muc HTR can do about that o_O

Not necessarily EASY to fly. Helicopters are an entirely different animal than fixed wing plane. They have very unique, and difficult, controls and FDE setups. HTR simply makes them act in the ways they're designed to. Again, not easy to fly, especially hard to hover, but as close to "realistic" as the sim has ever gotten. The developers of MSFS didn't pay much attention to helicopters, and it shows. HTR just corrects the sim's deficiencies.

But, of course, if you don't like it, just don't use it :D
As always, have fun to all!
Pat☺
 
Hi thanks for all replies! I know HTR, and I used for a while. It's realistic for sure but my thought is how worth is have a super realistic tool when I just sit on a chair in my room with limited hardware flight controls? I can't feel neither the heli under my chair nor the physic feedbacks. So i switched back to default Fsx trying to understand better heli models.

I found that what's called Cl_min (1402:48h) is blade's lift coefficient. If you put negative you have a downward force. Putting 0 there isn't any lift. Cl_max (1402:50h) seems linked to thrust, so could be a multiplier factor? Putting it to 0 or negative you have model erratic behaviours. Default Bell has a sort of torque that can be adjusted or increased by modifying Rotor drag (section drag coeff) and Rotor friction-solidity values (main solidity ratio). Putting them negative together with Cl_min and _max also negative you get nose yawing left (also previously and partially reported by Giordan Moore posts in Hovercontrol website). Bell has a little ground effect that could be adjusted modifying main rotor area as well, but it also impacts bank and pitch inertia.
 
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