Advanced Flight Model for other aircrafts!
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Far be it from me to contradict the expert. You would know more on the topic than I.
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that would result in very poor modelization
the only right way to do it is retro engineering of em charts and accel charts
Those charts aren’t that easy to get I presume…
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Hello again molnibalage,
I’ve already told you how I obtained those thrust curves, in a very rudimentary manner starting from those of the F-16’s Block 50 GE turbofan engine! I should now take Mav’s advice and try using an inverse-engineering technique to get the right curves (and correct values in the most critical parts) by knowing the exact plane’s forward accelerations at a certain drag coef. and plane mass, but only if I can get the correct plane’s acceleration charts at first, or from the plane’s e-m chart using the sustained turn rate, G-load, mass and true airspeed, do the job to estimate the CD (drag. coef) and then immediately find the Drag force = engine thrust for one particular point on the chart.
The e-m charts are much easier to get than acceleration charts (anyway they lead to the same thing), and so I’ll do my best to do what Mav said and painstakingly calculate the necessary thrust in as many points as possible (to obtain a more accurate curve for X altitude) and that’s as accurate as I can estimate thrust tables also from now on.
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Hi Yzangard,
The true pain is with the engine thrust estimation now. Let’s say that I can more or less be on the right track with the aero coefficients of lift and drag, yet I can’t be 100% sure even here that at some point the error margin wouldn’t get higher than 5% (especially at Mach numbers higher than the Mach drag rise and shock stall appearance Mach).
Took me long enough indeed until I was able to obtain more correct data for the MIG-23ML (that I started with), by correcting and re-correcting my mistakes and other errors, but now as I can better trust the aero results, it doesn’t take very long to get on with them.
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Those charts aren’t that easy to get I presume…
…no, they are not. But if you did have them, you could back out the thrust required to model engine behavior to match, and interpolate to fill the gaps. In fact, that is what you would have to do, I think. And outside of that, you’d also have to know something about how the subject aircraft flight control system works in order to model it’s maneuvering behavior properly…particularly for any fly-by-wire sort of aircraft. The F-16 FCLS and it’s control philosophy are a bit unique…and somewhat outdated by today’s engineering. It really doesn’t apply to any jet other than an F-16…unless that jet is also built by the same manufacturer. One can probably assume that for any aircraft.
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FYI: Topolo has made the Viggen FM based on actual performance charts. It’s not an AFM like the F-16 FM’s, but still quite close to the real thing.
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That sounds cool - now all you need is hi-fi Viggen avionics…nice! I wish there was a handbook for doing complete, accurate aircraft models as add-ons to BMS. I’m sure that dedicated 3rd party teams could come up with really great stuff, and then the BMS core team could continue to concentrate on what it does best - F-16 and world-sim AI modeling.
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FYI: Topolo has made the Viggen FM based on actual performance charts. It’s not an AFM like the F-16 FM’s, but still quite close to the real thing.
Still can’t get over how sluggish the Viggen is when you mount the centerline tank and AAMs. Definitely not what I expected from an aircraft that is supposed to get in and out of highway strips.
(Not the FM’s fault. I’m probably too used to the F-16.)
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That’s my doubt too. Not about the translation of the charts, Topolo has done a great job, but if that sluggishness is accurate. At a Swedish forum I’ve asked for rl pilot input in this regard.
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That’s my doubt too. Not about the translation of the charts, Topolo has done a great job, but if that sluggishness is accurate. At a Swedish forum I’ve asked for rl pilot input in this regard.
I’ve checked the charts from the docs and they at least look reasonable. Give me a shout if you hear back from that pilot.