Art-J Posted December 21, 2015 Posted December 21, 2015 Hello there. I'm trying to calculate minimal amount of fuel required for certain mission. Take-offs, climbs, descends and landings are covered in the (ENG draft) manual quite nicely, cruise settings on the other hand are more problematic. Table 9.2 gives "optimum speed that provides greatest range (minimum fuel consumption rate)". It doesn't give these rates though. Table 9.4 gives fuel consumption rates at various speeds for max range as well. There are 2 consumption rate figures, Q and Qmin. Qmin sounds like a rate for min consumption, BUT indicated speed figures for Qmin are almost twice lower then in table 9.2 (?). What is "Q" then? Q rates are higher, so for a moment I thought they might be rates for higher speeds as in table 9.2. However, after some calculations with this theory in mind, I get fuel consumption much lower than with Qmin from table 9.4. For example, if I calculate fuel consumption during a 100 km flight at 100 m altitude, with helicopter weight of around 11000 kg: a) IAS suggested by table 9.2 (230 km/h), with Q taken from table 9.4 (641 kg/h) yields consumption of ~280kg; b) IAS suggested by table 9.4 (120 km/h), with Qmin from table 9.2 (495 kg/h) yields consumption of ~415 kg! Which table and how should I use for these calculations then? i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10.
ED Team PilotMi8 Posted December 22, 2015 ED Team Posted December 22, 2015 Hello there. I'm trying to calculate minimal amount of fuel required for certain mission. Take-offs, climbs, descends and landings are covered in the (ENG draft) manual quite nicely, cruise settings on the other hand are more problematic. Table 9.2 gives "optimum speed that provides greatest range (minimum fuel consumption rate)". It doesn't give these rates though. Table 9.4 gives fuel consumption rates at various speeds for max range as well. There are 2 consumption rate figures, Q and Qmin. Qmin sounds like a rate for min consumption, BUT indicated speed figures for Qmin are almost twice lower then in table 9.2 (?). What is "Q" then? Q rates are higher, so for a moment I thought they might be rates for higher speeds as in table 9.2. However, after some calculations with this theory in mind, I get fuel consumption much lower than with Qmin from table 9.4. For example, if I calculate fuel consumption during a 100 km flight at 100 m altitude, with helicopter weight of around 11000 kg: a) IAS suggested by table 9.2 (230 km/h), with Q taken from table 9.4 (641 kg/h) yields consumption of ~280kg; b) IAS suggested by table 9.4 (120 km/h), with Qmin from table 9.2 (495 kg/h) yields consumption of ~415 kg! Which table and how should I use for these calculations then? See table 6.4. If you need calculate the fuel consumption for "Cruise airspeed" (when hels have minimum fuel consumption rates per one kilometres flight, for this example - 230kph), then it necessary 2.75 kg/km * 100 km = 275 kg for 100km flight. If you need calculate the fuel consumption for "Economic airspeed" (when hels have minimum fuel consumption rates per one hour flight), then it necessary 100 km / 120kph = 0.83 hour (the time for 100km of route). Then 0.83*495kg/hour=411 kg of fuel. All is correct!:) The "Economic airspeed" is necessary to use, if you need MAXIMUM time in flight (for example - during rescue mission, or observation mission, or Command and control mission..)
Cibit Posted December 22, 2015 Posted December 22, 2015 Great info thanks:) i5 8600k@5.2Ghz, Asus Prime A Z370, 32Gb DDR4 3000, GTX1080 SC, Oculus Rift CV1, Modded TM Warthog Modded X52 Collective, Jetseat, W10 Pro 64 [sIGPIC][/sIGPIC] Adding JTAC Guide //My Vid's//229th AHB
Art-J Posted December 22, 2015 Author Posted December 22, 2015 See table 6.4. If you need calculate the fuel consumption for "Cruise airspeed" (when hels have minimum fuel consumption rates per one kilometres flight, for this example - 230kph), then it necessary 2.75 kg/km * 100 km = 275 kg for 100km flight. If you need calculate the fuel consumption for "Economic airspeed" (when hels have minimum fuel consumption rates per one hour flight), then it necessary 100 km / 120kph = 0.83 hour (the time for 100km of route). Then 0.83*495kg/hour=411 kg of fuel. All is correct!:) The "Economic airspeed" is necessary to use, if you need MAXIMUM time in flight (for example - during rescue mission, or observation mission, or Command and control mission..) OK, I suspected it might have been range vs. endurance related. Thanks for the answer. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10.
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