Fred00 Posted September 20, 2018 Share Posted September 20, 2018 Like the title says, anyone else feel that it pitches up too much when rotating and lifting from the runway? Even if I just pitch up a bit and then let go of the stick it has a tendency to pull up far too high triggering the high alpha warning. I just feel that this behaviour is a bit strange and, without knowing, I question if the real plane really behaves like this. What do you guys think? Link to comment Share on other sites More sharing options...
outbaxx Posted September 20, 2018 Share Posted September 20, 2018 The pitch is very sensitive in the air too, if you fly fast and pull the stick fast 1-2cm you will over G. The issue with the take off is that below 250, whatever your weight, you can’t pitch up, so if you try to pull before 250 you will end up in aoa warning, especially if you go zone3. Hopefully this will be fixed in the future but for now you should wait after 250 and just use a very light pull to take off. And check your trim settings, if you don’t have a full external tank it should be 0, otherwise-3. Link to comment Share on other sites More sharing options...
Fred00 Posted September 20, 2018 Author Share Posted September 20, 2018 Yes, as it is now it requires alot of curve applied to the pitch axis to calm things down. I also think that they should have a look at this. Some planes feel awesome to take off with. For example the L-39 and the Mig-15. I'm not saying the Viggen should feel exactly like them, but something definitely feels off right now. Link to comment Share on other sites More sharing options...
metzgerov Posted September 20, 2018 Share Posted September 20, 2018 The pitch has variable gearing so at low speeds altitudes is is more exaggerated. It makes taking off very easy as you hardly have to pull back. If your HamFisted it would make life hard for you. I don't adjust my stick and its fine using a light touch on take off. At speed etc the pitch seems fine. On takeoff I would suggest a more gradual rotation. Its working as designed though! Link to comment Share on other sites More sharing options...
Reefer Posted September 20, 2018 Share Posted September 20, 2018 No problems here. It's working, as i follow the bottom HUD symbol on take off (the bottome line expands until it touches the vertical lines at about 300kph). Just don't yank the stick too much. Link to comment Share on other sites More sharing options...
outbaxx Posted September 21, 2018 Share Posted September 21, 2018 (edited) Anyone else feel that it pitches up too much? The pitch has variable gearing so at low speeds altitudes is is more exaggerated. It makes taking off very easy as you hardly have to pull back. If your HamFisted it would make life hard for you. I don't adjust my stick and its fine using a light touch on take off. At speed etc the pitch seems fine. On takeoff I would suggest a more gradual rotation. Its working as designed though! The gearing in pitch takes info from altitude and speed and reduce the rudder angle with increased rudder authority when you have the stick pulled at a specific angle. The idea was to have the same g pull with a specific stick angle regardless of speed and altitude. So it does not exaggerate anything, I would say it work the other way around. Edited September 21, 2018 by outbaxx Link to comment Share on other sites More sharing options...
Fred00 Posted September 21, 2018 Author Share Posted September 21, 2018 Okay, I did some testing. It turns out I've rotated too early. Letting the speed increase to ~300 km/h before lightly pulling back on the stick works much better. I still don't know if the tendency to pitch up if the speed is too low is built into the pitch gearing system or if it's a bug. Still, I will increase my take-off speed from now on. Link to comment Share on other sites More sharing options...
outbaxx Posted September 21, 2018 Share Posted September 21, 2018 (edited) Anyone else feel that it pitches up too much? Okay, I did some testing. It turns out I've rotated too early. Letting the speed increase to ~300 km/h before lightly pulling back on the stick works much better. I still don't know if the tendency to pitch up if the speed is too low is built into the pitch gearing system or if it's a bug. Still, I will increase my take-off speed from now on. Just remember that the max allowed speed on ground is 320km/h due to tire rotation Here you can see at what speed you can rotate depending on weight, throttle and temperature. Edited September 21, 2018 by outbaxx Link to comment Share on other sites More sharing options...
outbaxx Posted September 22, 2018 Share Posted September 22, 2018 So with a clean aircraft 100% fuel, air temp 15deg: Weight: 15500kg Zone2: Speed at rotation: 228km/h Zone3: Speed at rotation: 185km/h (min allowed is 190km/h) Aircraft with 100% fuel, full external tank, 16 bombs: Weight: 18850kg Zone2: Speed at rotation: 255+29-> 284km/h Zone3: Speed at rotation: 220+29->249km/h The added 29km/h is due to the external stores. Minimum recommended speed at rotation is 250km/h Link to comment Share on other sites More sharing options...
F900EX Posted September 25, 2018 Share Posted September 25, 2018 Here is a good example of a nice Viggen Takeoff. https://www.youtube.com/watch?v=DtvVpcNkkmU&t=5s Link to comment Share on other sites More sharing options...
outbaxx Posted September 26, 2018 Share Posted September 26, 2018 When doing a “control check flight”, one part is to check AoA15 at 6km. -Decelerate to AoA 15 and and compare Vi at 1G. (AoA15 should correspond to Vi 240-280km/h with fuel 55-65%) -Maintain AoA15 and 1G, give fast stick aft (very fast). (High Alpha Warning should activate) Fun to try :) Link to comment Share on other sites More sharing options...
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