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Guest JeanLuc_

G Force - Too high?

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As I am developing a new HUD, I now have the G force in front of my eyes all the time.Flying with the great F-16 from Kirk Olsson, I noticed the acceleration could be as high as 13 or 14G during high-G turns (90

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This is probably a consequence of the Aircraft's flight dynamic modelling. The aircraft is over-performing!! You could tweak the aircraft.cfg and the FDE to try to bring it more in to line. Or as work-around you could insert a scaling factor into you G-gauge and instead of dividing by 624 divide by 970 instead (624 /9 *14) This will bring the 14G figure down to 9G...However you might find unrealistic readings in more gentle manoeuvres.RegardsJim

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If it is a problem in the FDE, I will certainly not modify it. I know nothing about FDE, and I know Kirk is an expert, so I will not modify his F-16. I thought about cheating with the value display, but it is not a good idea because, as you said, the G-force value is valid for low acceleration (up to 4G).Thanks for the idea anyway ;-)Eric

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Could be realistic values, but pilot blackout.Max G-force about 16-17G(?)Some airforces limits the G-forces by the fly by wire system computers to say 9G, some, like the Israelis to 11G.Told to me by a F16 jockey now flying over Afghanistan.So you could build in a limiting factor:G-force bigger than your limiter then decrease angle of attack automatically or something like that.Jan"Beatus ille qui procul negotiis..."

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Well, first off, the F-16 is limited to 9 Gs, period. That is not an airframe limitation; the onboard computers will not allow more than 9Gs. Remember, the F16 uses an almost rigid joystick. Maximum movement is (IIRC) only 3/8", about 10mm. Transducers measure the amount of force on the stick and adjust the flight controls accordingly. When 9Gs are reached, the computers back off on control surface displacement, regardless of the pilot's control input.It's a good, pilot-proof, system. An F-16 jock can bank and yank as hard as he wants without overstressing the airframe.So the bottom line is, FDE adjustments aside, your G meter should max out at 9.Cheers,Glenn

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I understand the problem, but I don't plan to implement a fly-by-wire system of this F-16. My objective was to develop a realistic HUD, not to develop a FBW system. I might think about it later...Thanks for your help !!Eric

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In which case you need to put in an IF statement before the String statementif(G>9) G=9:I know it's not in XML notation!!!! But I don't want to take away your funRegardsJim

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Yes, I can do this, but it will make the G force display unrealistic. I may limit it to 11G instead, this might be a good compromise.Eric

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Eric,you have already developped a FBW for the Wilco A320? you could consider adding a "FBW" background task in the HUD just for this?!Otherwise, you may consider non linear mapping of the G, i.e. from 0 to 9 it is like the normal G, then from say 9 to 12 it goes 9 to 11 and from 12 to 15 it goes 11 to 12.Hope this helps!

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Ooohhh Yesssss, I did ;-)You know I have developed the Wilco Airbus FBW system, but I am not sure it can be transposed so easily to a Mach 1+ jet fighter...I might think about it though :-rollAnother interesting option is the transposition of the F-16 HUD to the Airbus. Maybe when I will have some time...In the meantime, here are some pics of my F-16 HUD. I hope I will have some time, one day, to capture videos, it is beautiful when animated. You can see the HUD can be integrated in a panel or used in full-screen, and the brightness is fully adjustable (this images had to be resized to respect the size constriant of this forum).Eric

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This is looking good Eric! is this GDI+ or bitmap based? One thing I've spent time a while ago, was trying to have antialiased drawings over the 3D view, otherwise, drawing on the transparent static would always give jaggies at some point. We can't tell from the resized screenshots of course. I'm curious if you get it work antialiased though? I've partly succeeded in achieving that, but it was far from being efficient in my point of view (I did not want to sacrifice any FPS just for this, and this was having some sort of FPS hit anyhow).

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This HUD is using GDI+ with anti-aliasing. I thought the same as you (les grands esprits se rencontrent) and the solution I found to draw anti-alised on top of the 3D view was very FPS-consuming, so I forgot it. Today, the HUD anti-aliasing is computed by GDI+ on the base of a black background. It gives strange results sometimes when the sky is very bright, but it looks perfects at dusk or at night.The anti-alising is not 100% perfect, but the impact on the FPS is VERY low, even if full screen mode.Eric

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Well, so there are aliasing issues. I guess we probably though something similar: capture the 3D window pixels, and draw over.Drawing against a black background is not great indeed when looking to the sky, and I'm yet to find something to my taste too.Well, when I have time for this, I may search again a solution.Thanks for sharing ideas!

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