Vladinsky Posted February 4, 2017 Share Posted February 4, 2017 Its been feeling really slow to fly around with some of the larger stores so I decided to compare it to the expected top speeds and acceleration times listed in SFI AJ37 Del 3 using the supplied loadouts. Clean acceleration and speed is pretty close but as soon as stuff goes under the wings performance is greatly reduced which leads me to believe that drag is the main culprit. Bomb drag is most certainly too high. All tests are started at M0.55 and flown 20-40m above the black sea in altitude hold. Max dry thrust. Weight: Starting weight -275kg ISA 15C 1013mbar. Time and speed verified in tacview. Clean Target speed: M0.89 in 2:15 minutes. Result: M0.85 in 2:15 minutes. Top speed of M0.88 took 3 minutes. Loadout 1(2 RB24 + KA(U22)/KB + XT) Target speed: M0.85, in 2:30 minutes. Result: M0.75 in 2:30 minutes, would not accelerate further. Loadout 2(1 RB04 + 1 RB24 + KA(U22) + XT) Target speed: M0.83 in 2:30 minutes. Result: M0.74 in 3:10 minutes, would not accelerate further. Loadout 3(3 Rocket pods + KB + XT) Target speed: M0.77 in 2:40 minutes. Result: M0.75 in 3:30 minutes, would not accelerate further. Loadout 4(16 HE bombs + XT) Target speed: M0.77 in ~3:00 minutes. This was the worst one by far, the plane was not capable of sustaining the minimum speed required to actually start the test. Not even max zone 2 was enough to reach M0.77 I've no doubt messed up somewhere though, don't hesitate to double check. (No, I really didnt have anything better to do last night:helpsmilie:) 3 Link to comment Share on other sites More sharing options...
scaflight Posted February 4, 2017 Share Posted February 4, 2017 (edited) Good effort! I know that having the automatic fuel regulator on has had negative impact on speeds during high altitude flying, but I'm wondering if it has played a part here as well... Would you care to double-check any of these with the fuel regulator turned to manual? I don't necessarily see how that bug could play into this scenario, but it's the only issue that manifests in lower speed that we know of (AFAIK). (I absolutely would do this myself, but I'm going to bed. I'll do it in 8 hours or so, if no one else has) Edited February 4, 2017 by scaflight Link to comment Share on other sites More sharing options...
amalahama Posted February 4, 2017 Share Posted February 4, 2017 Also, are the fuel weight in all scenarios you checked the same as in the charts? I cannot check from the info you provided. Regards Link to comment Share on other sites More sharing options...
renhanxue Posted February 4, 2017 Share Posted February 4, 2017 (edited) edit: there was something here that was wrong, below is correct: Vladinsky, takeoff weight minus 275 kg is correct for the acceleration graphs, but the level flight envelope graphs I just now discovered use the term "flygvikt", which is defined as 70% fuel for an aircraft without the drop tank and 100% for an aircraft with the drop tank. 100% is defined as 4200 kg. Great work, by the way! Edited February 4, 2017 by renhanxue Link to comment Share on other sites More sharing options...
Vladinsky Posted February 4, 2017 Author Share Posted February 4, 2017 (edited) Thanks for checking guys, I did do a run with manual fuel regulation but there was no change. That seems to be a non ISA/high alt issue only. E: I flew a top speed only test with adjusted "flygvikt" and saw a consistent increase of about M0.01 across the board. Edited February 4, 2017 by Vladinsky Link to comment Share on other sites More sharing options...
Schmidtfire Posted February 5, 2017 Share Posted February 5, 2017 Seems like bombs create massive drag. We struggeled to stay in fornation during an MP mission. AJS37s with XT and 4 rocket pods+Rb24 had no issues. But AJS37s with XT, 8 bombs on two racks and 4xRB24 had problems keeping the speed over 500-600km/h in level flight and on full military power. There was a bit of wind that might have added to the issues we had. But the general feeling was that the drag for bombs was very high. Or is it standard procedure to always fly in afterburner when carrying bombs? Link to comment Share on other sites More sharing options...
renhanxue Posted February 5, 2017 Share Posted February 5, 2017 No. The bombs are very draggy in reality too but far from that draggy. Link to comment Share on other sites More sharing options...
Hesgad Posted February 6, 2017 Share Posted February 6, 2017 Seems like bombs create massive drag. We struggeled to stay in fornation during an MP mission. AJS37s with XT and 4 rocket pods+Rb24 had no issues. But AJS37s with XT, 8 bombs on two racks and 4xRB24 had problems keeping the speed over 500-600km/h in level flight and on full military power. There was a bit of wind that might have added to the issues we had. But the general feeling was that the drag for bombs was very high. Or is it standard procedure to always fly in afterburner when carrying bombs? Yep bombs seem to create far too much drag barely able to hold her level without the AB Link to comment Share on other sites More sharing options...
mattebubben Posted February 10, 2017 Share Posted February 10, 2017 This was a part in Todays changelog. Updated drag on bombs and bomb pylons, and external fuel tank. So hopefully that means this problem has been fixed. Link to comment Share on other sites More sharing options...
Cobra847 Posted February 10, 2017 Share Posted February 10, 2017 This is just the first tweak of this sort. The issue may persist until we finish tweaking :) Nicholas Dackard Founder & Lead Artist Heatblur Simulations https://www.facebook.com/heatblur/ Link to comment Share on other sites More sharing options...
Vladinsky Posted February 10, 2017 Author Share Posted February 10, 2017 Loadout 4 acceleration timing and top speed seems much more consistent with the other loadouts now, reaching M0.7 in 3 minutes and not accelerating further. I've not tried any of the other yet but I'd expect a small time reduction and top speed increase from the fuel tank change. Well done:thumbup: Link to comment Share on other sites More sharing options...
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