Confused with the CRUS sub modes (or am I?)
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All of them individually are straight forward enough to understand completely ,but each seems to have the same base idea (conserving fuel) so im confused at which is best used for what situation or preffered outcome.
RNG - will tell me the very BEST speed to to meet in order to concerve the maximum fuel at my CURRENT altitude towards my current STRPT.
HOME - Will give me the best speed but ALSO the best altitude - which sounds like will ultimately conserve me more fuel ?, and im assuming this is a choice you would choose only of your altitude is optional.
BUT THEN…
EDR - Endurance really throws the wrench in my gears as it sounds exactly the same as RNG other than it gives me the time till my bingo ,and a mach #… however RNG tells me what my fuel will be when I arrive… ???
RNG & EDR are the same other than the difference being time till my bingo ,or what fuel I will have in IBS’s whem I arrive.
Coukd someobe please clarify maybe what each one is best USED for given the possible scenarios where one is better used than the other ?.
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The way I understand it, RNG and EDR are sort of opposites in some sense.
RNG tells you how fast to go at your altitude to maximize your range.
EDR tells you how fast to go at your altitude to maximize your flight time.They are not necessarily the same thing, even though they might sound like it at first (maximum flight time does not equal maximum distance traveled). So basically, you want to use RNG when you want to end up with the most fuel upon arriving at a location, while you want EDR when you want the most loiter time around a location. As for HOME, it simply tells you the best way to get back home (or whatever steerpoint you end up selecting).
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Got it !.. thanks man for some reason I was reading the manual and going in circles. Sometimes I think I spend too much time reading and read into it too much. That all makes sense and Im sure Home explains its self… probably best for returning to base and landing.
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Range is distance and endurance is time.As a rule best range speed is faster than endurance (e.g. 250 v 210). They are used generally when you are stuck at whatever altitude (planned leg or in a hold) and want to to maximize the appropriate figure. Those two modes being best-for-current-alt and not absolute is interesting and makes me wonder about absolutes related to this goal.
From charts, picking 28klb, DI 0 (KTAS @ PPH ALT):
E 400 @ 2472 30K
E 438 @ 2436 35K
E 472 @ 2574 40KEndurance peak is happening somewhere in the vicinity of 35kft, 30 and 40 having (slightly) higher fuel flow. If absolute endurance is anything like absolute specific range then the best performance is at 35,500’ which is consistent.
Home profile is a 3-element climb-cruise-descent guided package that should dump you 10,000’ over the selected destination with the maximum fuel remainder. This is the “I was in afterburner dogfight longer than I would have liked now I have to get my butt home” mode. Everyone should practice the home profile to be amazed at just how fuel efficient it is and to encourage themselves never to need it because of how awfully boring (slow) it is.
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Frederf, you don’t specify any loadout for this altitude. I suppose it varies? If not, it’s doubly interesting.
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I mean, it does maximise fuel savings. I obviously dont have first hand experience with the implementation of this policy, but I understand its USAF policy at least to develop unit practices that treat aviation fuel as a precious resource.
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don’t they also have a policy of 800Lbs min fuel left in the tanks over home plate ?
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Eolmin, it varies with gross weight and drag index. I actually meant to give figures for DI 100 but I went brain dumb and filled in DI 0 numbers so I did the easy thing and changed my initial conditions from 100 to 0.
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don’t they also have a policy of 800Lbs min fuel left in the tanks over home plate ?
800/1000 by block early/late and initial or final approach so touchdown could be a little less. Minimum and emergency fuel are 200 and 400 pounds less than normal recovery.
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Normal recovery is 1200 on initial or FAF, for blocks 40 and onwards. minimum is 1000, emergency is 800. Subtract 200 for blocks before 40.
So long as Im looking at it, this is what I was referring to:
2.6. Fuel Conservation. Manage aviation fuel as a limited commodity and precious resource. Design procedures for optimal fuel use and efficiencies throughout all phases of mission execution, to include ground operations, flight plans, power settings and climb/descent profiles. Incorporate enroute tasks to make maximum use of airborne learning opportunities.