strikeeagle Posted October 28, 2013 Posted October 28, 2013 I noticed extreme efficiency with full afterburner at 65,000ft in level flight. I was just over Mach 1 with a ground speed of about 1000 knots. Fuel consumption seems to act a bit weird in the F-15. The higher you go, the less fuel you burn in reality. Even in burner. So technically fuel flow should be far less at that altitude vs down low. After all, it's just a game right? [sIGPIC][/sIGPIC] Chris
GGTharos Posted October 29, 2013 Posted October 29, 2013 I noticed extreme efficiency with full afterburner at 65,000ft in level flight. I was just over Mach 1 with a ground speed of about 1000 knots. Fuel consumption seems to act a bit weird in the F-15. Very weird. [sIGPIC][/sIGPIC] Reminder: SAM = Speed Bump :D I used to play flight sims like you, but then I took a slammer to the knee - Yoda
strikeeagle Posted October 29, 2013 Posted October 29, 2013 (edited) Very weird. Remember, that's for an "A". Current "C's" do not have the same engine, performance, or burn of a "A". A/B - F-100PW-100 C/D/E - F-100PW-220 E - F-100PW-220 or -229 Edited October 29, 2013 by strikeeagle [sIGPIC][/sIGPIC] Chris
howie87 Posted October 29, 2013 Posted October 29, 2013 Very weird. I'd be interested to see some numbers for even higher speeds/altitudes. I know that thinner air = leaner mixture and less fuel flow but I thought with full afterburner on you'd still be dumping a huge amount of fuel into the tail pipe no matter how high up you are. Fuel consumption seems almost more dependant on air speed than throttle setting. I wonder if this a function of the engine management system. As a test I was cruising at angels 50 in falcon BMS in full afterburner and cut the throttle to idle. I pointed the nose down and watched fuel flow INCREASE in the decent. It only began to reduce after I levelled out and the turbine started to wind down as my airspeed bled off.
GGTharos Posted October 29, 2013 Posted October 29, 2013 I'd be interested to see some numbers for even higher speeds/altitudes. I know that thinner air = leaner mixture and less fuel flow but I thought with full afterburner on you'd still be dumping a huge amount of fuel into the tail pipe no matter how high up you are. Fuel consumption seems almost more dependant on air speed than throttle setting. I wonder if this a function of the engine management system. You do have to have some minimum RPMs depending on air density etc. Your idle RPMs will be higher at high altitude. The F-15C SFM doesn't model any of that. As a test I was cruising at angels 50 in falcon BMS in full afterburner and cut the throttle to idle. I pointed the nose down and watched fuel flow INCREASE in the decent. It only began to reduce after I levelled out and the turbine started to wind down as my airspeed bled off. I don't really care what BMS does and neither do the devs. What ther eal plane does is what matters. BMS doesn't get everything right either (though I don't know about this particular thing :) ) [sIGPIC][/sIGPIC] Reminder: SAM = Speed Bump :D I used to play flight sims like you, but then I took a slammer to the knee - Yoda
strikeeagle Posted October 29, 2013 Posted October 29, 2013 (edited) Fuel consumption seems almost more dependant on air speed than throttle setting. No, fuel consumption in a turbine powered airplane is dependent more so on temperature and altitude. Oh add wind too. I wonder if this a function of the engine management system. In the case of the F-15, it's the engine control system. Fuel is scheduled by a UFC (Unified Fuel Control) in the old -100 engines and a MFC (Main Fuel Control) in -220/-229's. The key word is "schedule". The pilots sets what ever thrust is required by of course moving the throttle. Via linkage, the throttle is connected to the main fuel pump. The main fuel pump sends fuel to the MFC and the DEEC (Digital Electronic Engine Control) that controls the entire engine. Depending on outside temperature, altitude, and air pressures at the fan case and exhaust will determine fuel flow. For burner, a valve opens on the AB fuel pump that supplies fuel directly the AB spray rings. The AB fuel pump is independent of the MFC or the older UFC. Hope this helps. Edited October 29, 2013 by strikeeagle [sIGPIC][/sIGPIC] Chris
fitness88 Posted October 31, 2013 Author Posted October 31, 2013 Just found this: 153 - F-15C Fuel Consumption Guage is showing wrong fuel consumption Pasted from <http://forums.eagle.ru/showthread.php?p=1905309&highlight=HSI> Has this been fixed?
Robin_Hood Posted October 31, 2013 Posted October 31, 2013 I tested it the other day - not extensively, but at a set medium altitude and indicated fuel flow, fuel was indeed burned at the indicated rate :thumbup: I didn't test with different fuel flows, so it may need more testing to be 100% sure. So it would seem that it is fixed, and I'm very thrilled about that 2nd French Fighter Squadron
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