Tiger-II Posted January 6, 2023 Posted January 6, 2023 Hi, Some time ago I profiled the F-16 in another sim to find the optimum AoA to fly for a given gross weight/drag factor. The results were quite interesting. Empty, the optimum AoA was 6 degrees; at medium weight 4.2 degrees, and at max weight, 4.5 degrees. Higher drag factor added 0.5 degrees to the required AoA (so max weight with high drag stores worked out at 4.7 degrees). I think AeriaGloria was working on making determinations about drag index for the Jeff. Would anyone be interested in optimum profile for the Jeff? It takes about a day to compile the figures, and I hope the flight model is pretty much done, so it won't be a waste of time to fly lots of profiles with different stores to collect data. 2 Motorola 68000 | 1 Mb | Debug port "When performing a forced landing, fly the aircraft as far into the crash as possible." - Bob Hoover. The JF-17 is not better than the F-16; it's different. It's how you fly that counts. "An average aircraft with a skilled pilot, will out-perform the superior aircraft with an average pilot."
BigBorner Posted January 9, 2023 Posted January 9, 2023 Stupid question maybe, but: Why is it important to know the optimal AoA? Just curious.
Pavlin_33 Posted January 9, 2023 Posted January 9, 2023 (edited) 1 hour ago, BigBorner said: Stupid question maybe, but: Why is it important to know the optimal AoA? Just curious. Not a stupid question at all. To put it simply, AoA (angle-of-attack) determines how much drag force (force that opposes motion) the airplane will produce. In general, the higher the AoA the higher the drag. Every airplane has it's optimum AoA where it has the lowest lift-to-drag ratio. In airliners this number is usually around 4 degrees and this is what determines the most optimal cruising speed. Think of AoA as an abstraction of the airplane's performance. We usually use speeds to do this, 'cause as humans this is something more tangible for us, but if you think about it AoA is the true performance indicator. What I mean by this is think of approach/landing speeds for the same airplane at different weights: you would need to know what speed is perfect for each weight. If you use an AoA, and you know what is the best value for it to use on landing, then you don't even need to care about your airspeed. As long as you have AoA value correct, what ever speed you are going at is the correct one. Same goes for stalling, cruising, etc. Edited January 9, 2023 by Pavlin_33 2 1 i5-4690K CPU 3.50Ghz @ 4.10GHz; 32GB DDR3 1600MHz; GeForce GTX 1660 Super; LG IPS225@1920x1080; Samsung SSD 860 EVO 1TB; Windows 10 Pro
BigBorner Posted January 9, 2023 Posted January 9, 2023 Aaaah, okay, now I understand! Thank you very much! 1
Napillo Posted January 9, 2023 Posted January 9, 2023 On 1/6/2023 at 9:50 AM, Tiger-II said: I hope the flight model is pretty much done, so it won't be a waste of time to fly lots of profiles with different stores to collect data. they said they're changing the pylons drag, so I'd wait until at least the first release of the updated drag before collecting data.
BigBorner Posted January 10, 2023 Posted January 10, 2023 I hope it doesn’t change that much, otherwise i have to redo my bingo and loiter time calculator
AeriaGloria Posted January 10, 2023 Posted January 10, 2023 7 hours ago, BigBorner said: I hope it doesn’t change that much, otherwise i have to redo my bingo and loiter time calculator You made one? Black Shark Den Squadron Member: We are open to new recruits, click here to check us out or apply to join! https://blacksharkden.com
BigBorner Posted January 13, 2023 Posted January 13, 2023 Am 10.1.2023 um 18:48 schrieb AeriaGloria: You made one? Yes, i did. It’s working okay. Did some test runs at different altitudes, loadouts and throttle setting and baked it into some formulas. It’s pretty rudimentary as only calculates fuel and loiter time for 10 and 25k feet. However, there it is: https://docs.google.com/spreadsheets/d/1sOolJDhRb2Tn4TorFLv9gJqm7G4_03v36txyI_nRqAc/edit 2
oyen20 Posted January 13, 2023 Posted January 13, 2023 On 1/6/2023 at 5:50 PM, Tiger-II said: Hi, Some time ago I profiled the F-16 in another sim to find the optimum AoA to fly for a given gross weight/drag factor. The results were quite interesting. Empty, the optimum AoA was 6 degrees; at medium weight 4.2 degrees, and at max weight, 4.5 degrees. Higher drag factor added 0.5 degrees to the required AoA (so max weight with high drag stores worked out at 4.7 degrees). I think AeriaGloria was working on making determinations about drag index for the Jeff. Would anyone be interested in optimum profile for the Jeff? It takes about a day to compile the figures, and I hope the flight model is pretty much done, so it won't be a waste of time to fly lots of profiles with different stores to collect data. Maybe when the pylons update so you don't waste your time but it would be wonderful to have! Thank's that could be very useful!
Napillo Posted January 13, 2023 Posted January 13, 2023 (edited) 2 hours ago, BigBorner said: It’s working okay. It seems to overestimate fuel needed, when I fly at 3 or 4 aoa at 26,000ft using about 90% rpm, I can cover about 200nm with dual sfw, tpod, pl-5eii, I takeoff without AB, slow climb of about 6 degrees to altitude at 95% rpm, autopilot nearly always on. I have a loiter time of about 5/10 minutes and a 50nm divert. Edited January 13, 2023 by Napillo
BigBorner Posted January 13, 2023 Posted January 13, 2023 Yeah, makes sense. All the calculations assume 100% throttle (combat mode activated) and there is a 10% margin on top (changeable). it’s not for exact fuel planning to save every pound.
Napillo Posted January 14, 2023 Posted January 14, 2023 12 hours ago, BigBorner said: assume 100% throttle ah, I'm assuming that people that want the longer range would fly slower, but maybe people don't think that way.
BigBorner Posted January 14, 2023 Posted January 14, 2023 I started to do tests with 90% throttle, but loaded at 25k the aoa grew and grew. So I left it at that, remembered that you rarely get more than 150nm to AO anyway and most people are inpatient.
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