SkyObscure Posted March 3 Share Posted March 3 Hi All, I’m a novice where DCS is concerned and trying to understand the FLCS on the Viper. Apologies if this is in the wrong topic, but it seemed most appropriate. The main issue is trim. My understanding of the system is that under most circumstances the pilot doesn’t trim. The attitude is set and up to 15’ AoA the FLCS will maintain 1g. Trimming in either direction changes the g that will be maintained and in straight flight this will introduce a pitching moment in one direction or the other (ultimately making manual trim fairly redundant unless you want to fly a constant AoB orbit). On climb out with the trim gain set to 1g I can set a pitch attitude of 10’NU and go heads in to make a switch selection and a few seconds later return to see the pitch attitude has increased by up to 5’. I can’t take my eye off it for anytime at all and I’m finding I need a small amount of stick forward to hold the nose attitude in the climb. By definition this is an out of trim condition. The question is why? I tried manually trimming in the early stages, but it makes matters worse. I have considered it may be a controller issue an introduced a dead zone, but that has no effect. The only thing I can think of is that I’m misunderstanding how the system works. Maybe, there’s a pitch power couple at play? Any help appreciated. Link to comment Share on other sites More sharing options...
Solution razo+r Posted March 3 Solution Share Posted March 3 It's important to understand how or what 1G is maintained by the FLCS. As you said, the F-16 maintains 1G, but it maintains 1G on the vertical axis. So whenever you are not perfectly level, so when the vertical axis of the plane isn't pointing straight up into the sky, your aircraft measures an ever so slightly value of less than 1G on that axis. And in order to bring the aircraft back to 1G on the vertical axis, it induces a pitch up moment to get back to 1G. The more you pitch up, the more the FLCS is inducing a pitch up moment to reach 1G. In extreme cases like straight up/down or inverted, you'll see this behaviour very clearly. Despite no inputs, the FLCS is pitching up to maintain 1G on the specific axis. 1 Link to comment Share on other sites More sharing options...
SkyObscure Posted March 3 Author Share Posted March 3 Many thanks, razo+r. I knew there was something I was missing and hadn't thought about the accelerometer being fixed to the normal axis of the aircraft. Pretty obvious when you think about it! Cheers Link to comment Share on other sites More sharing options...
Trigati Posted March 3 Share Posted March 3 Also there is a speed element here, as you climb out you might be still accelerating (or decelerating) so the pitch change is to maintain that 1g as the lift produced changes due to the airspeed on the wings changes.Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
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