159th Guards Aviation Regiment

Pirates Of The Crimean
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 Post subject: Fuel Economy
PostPosted: Fri Jul 11, 2008 11:40 am 
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Hangar Rat
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Joined: Fri Jun 27, 2008 1:07 pm
Posts: 22
As prescribed by 159th_Archer on the old www.the159th.com:

In the interests of actually getting all SW AC recovered without running out of fuel, I conducted a quick test.

A 25t was set-up on AP at different alts and speeds, and over a 200km straight course. No load, and fuel load 1510kg.

Altitude - Airspeed - Throttle setting - Fuel remaining

T1. 300m - 500 - 75% - 650kg
T2. 300m - 890 - 90% - 500kg

T3. 2000m - 500 - 76% - 740kg
T4. 2000m - 790 - 90% - 630kg

T5. 4000m - 400 - 82% - 810kg
T6. 4000m - 500 - 84% - 890kg
T7. 4000m - 660 - 90% - 800kg

LOADED (16650kg AUW)
T8. 4000m - 400 - 92% - 580kg
T9. 4000m - 470 - 95% - 620kg

LOADED (19500kg AUW)
T10. 1000m - 540 - 90% - 390kg

Sorry if the table is not as clear as it might be (and I might have made the odd entry error), but the lesson is pretty clear -and obvious...- height saves fuel as does lower (though NOT slowest) speed. Not dragging an over-loaded AC around is also good. Seems the developers did pretty well, here.

T6 is interesting, as at the mid throttle setting it was found fuel ecnomy was better than both the lower/higher settings.


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 Post subject: Re: Fuel Economy
PostPosted: Fri Jul 11, 2008 11:43 am 
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Hangar Rat
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Joined: Fri Jun 27, 2008 1:07 pm
Posts: 22
As prescribed by 159th_Invicta on the old www.the159th.com:


Here are my findings. All flown with an empty su33 with a full tank of fuel.

This first series was flown by setting the throttle to a certain amount. The 33 won't stay airbourne at 75% so I changed that to 85%. At 6000m Alt 85% wasn't enough either, so had to change that to 90%. When flying without the auto-speed hold, the aircraft tends to accelerate or decelarate as the AoA changes.


Code:
       ALT    IAS    THROTTLE    FUEL Remaining

1.    300    810       85%       8400
2.    300    1180      100%      6950

3.    2000   750       85%       8550
4.    2000   1180      85%       8250

5.    6000   700       90%       8650
6.    6000   850       100%      7900



This second batch I used speed hold to fly at a set speed instead of a set throttle setting.



Code:
       ALT    IAS    THROTTLE    FUEL Remaining

7.    6000   360       87%       8450
8.    6000   600       86%       8750 <--

9.    8000   670       93%       8600
10.   8000   600       90%       8750 <--



To conclude, if you want to save fuel, fly high and fly fast enough to keep your AoA low (<5). I'd recommend option 8. Set altitude hold to 6000 and speedhold at 600.


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