A few questions

[r601020]

re: Estimated Fuel Burn

Fairly new to SIM, et. al., and the P51. I'm curious about a discrepancy.

Based on previous flights, I'm getting, roughly, 8+mpg in the Mustang while in-flight. Therefore, calculating 250 nautical miles / 9 = 28 gallons, adding 5 gallons for taxi and 10 gallons for takeoff, is 43 gallons. I loaded 45 gallons.

The estimated fuel burn in FSX:SE Navlog is double that.

My first A2A plane was the Spitfire, and FSX:SE estimated fuel burn was fairly close, sometimes over, sometimes under, but this is way off compared to actual in the P51. Granted, because the Spitfire is a gas hog, I had to learn a lot about fuel efficiency, which applies, but I'm not this good, and quite the novice.

Excluding dodging mountaintops, mostly flew around 10,000ft, landing with 16 gallons remaining.

Thanks in advance for any feedback.

[robert41]

Because the Accusim runs outside of FSX, the FSX estimates are usually different. Best to go by the shift 2 panel fuel, range notes when using an Accusim aircraft.

[r601020]

Because the Accusim runs outside of FSX, the FSX estimates are usually different. Best to go by the shift 2 panel fuel, range notes when using an Accusim aircraft.

After some reading, I'm not sure that FSX:SE is incorrect, but basing an estimated GPH on WWII documents of 60 GPH.

Cruising as economically as possible, and usually without a full tank, no ammo, etc., I'm at less than 30 GPH, explaining why it would be half their estimated fuel burn.

[r601020]

re: bearings

Is there a particular setting with manifold and RPM that is less stressful when uh, doing stuff? Or, how long can I fly upside down before my mechanic unfriends me?

https://youtu.be/0zOhVvqf4os

https://youtu.be/mEoyQHyIXH8

[robert41]

I like to use 41-43MP and 24-2500RPM when cruising. If below the critical altitude for this setting. Good speed, good temps. No issues with this.
I have also used 46MP and 2700RPM, it's climb setting, for long cruises and maneuvers, without any problems. This should be it's maximum continuous power setting.
Next up would be combat/military power. Throttle to the gate. 61-62MP and 3000RPMs. Limit this to about 10minutes. Temps get up there. Then give the engine a rest.
Breaking the gate is WEP, again limit this. And inspect the engine afterwards.
For something economical, I would not go below 25MP. This can lead to fouled plugs. I have done this. Then pull the rpms back under 2000. See how far you can go. But there is little need for that, the 51 was built for speed and carries a lot of fuel for range.
Upside down, for about 10 seconds at a time. The oil system does not work upside down.

[Alan_A]

IIRC, a while ago Scott suggested 30MP and 1800 RPM in the neighborhood of 15,000 - 18,000 feet as a sort of fuel-economy sweet spot. Even at lower altitudes, the civ model will give me about 250 knots at taht setting at about 30 gph. Decently fast and easy on the engine. The military version is a bit slower thanks to the extra weight, but not by too much. Worth trying on those days when you're not in a hurry.

Now I'll go try the higher settings on days when I *am* in a hurry...

[robert41]

I did try Scott's settings with the Mil version. I do not remember the MP and RPM right off. Was at 17000 or 17500ft in low blower. The Mil 51 could not keep enough speed with it's heavier weight and more drag.
This aircraft was built for speed and does it well . Even at higher power settings, it still has some impressive range.

[r601020]

Thanks for the suggestions.

Have tried these settings in the shorter hops, and then used what I learned in climb today to 30k, but modified somewhere about the half-way point in a 900 nautical mile trip to ensure not running out of fuel. FSX:SE estimated this trip at a fuel burn of 350 gallons, which is, probably correct based on 60 GPH.

cruise measurement #4:
N58° 28.69' E165° 12.28'
altitude 26,000
throttle 65%
manifold 31.5
propeller (RPM) 30%
tachometer 1924
40 GPH
airspeed 219mph
groundspeed 328mph
166 gallons remaining, range 1350 miles

Landed with 111 gallons remaining. I'll run the next test at 50 GPH (cruise).

Landing in Kamchatka, Russia (UHPP)
https://youtu.be/I41-Wz0j4V4

[r601020]

FSX:SE Estimate
Memanbetsu -> Yamagata
Distance: 397.0 nm
Estimated fuel burn: 168.6 gal / 1011.5 lb
Estimated time en route: 1:26

My Estimate
397 Nautical Miles / 250 MPH Airspeed = 1.588 Hrs
1.588 Hrs * 52 GPH = 82.576 gallon Fuel burn
add : startup, taxi, take-off, landed taxi
100 gallons

cruise measurement #1: (after climb)
N42° 26.36' E141° 48.93'
altitude 22,000
throttle 66%
manifold 32.6
propeller (RPM) 64%
tachometer 2491
50 GPH
airspeed 253mph
groundspeed 353mph
66 gallons remaining, range 462 miles

cruise measurement #2: (mid-flight)
N41° 0.08' E140° 42.31'
altitude 21,500
throttle 68%
manifold 34.0
propeller (RPM) 65%
tachometer 2508
54 GPH
airspeed 256mph
groundspeed 355mph
50 gallons remaining, range 335 miles

cruise measurement #3: (before decent)
N39° 33.91' E140° 29.39'
altitude 21,000
throttle 68%
manifold 34.0
propeller (RPM) 65%
tachometer 2508
54 GPH
airspeed 257mph
groundspeed 354mph
37 gallons remaining, range 246 miles

Landed with 30 gallons remaining

[Gypsy Baron]

The A2A P-51's and other aircraft have the fuel systems and engine characteristics coded completely outside of FSX so numbers obtained from FSX are not going to jive with the A2A Accu-Sim 'actuals'.

I only use the A2A 2D pop-up data for obtaining fuel and range data.

Paul

[Lewis - A2A]

The A2A P-51's and other aircraft have the fuel systems and engine characteristics coded completely outside of FSX so numbers obtained from FSX are not going to jive with the A2A Accu-Sim 'actuals'.

I only use the A2A 2D pop-up data for obtaining fuel and range data.

Yes that is 100% correct, the Accu-sim simulation engine provides the high fidelity simulation including the full combustion engine from spark to exhaust.

thanks,
Lewis

[r601020]

Thanks again for the suggestions.

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Microsoft Flight Simulator Flight Plan
Sunan -> Beijing Capital
Distance: 454.4 nm
Estimated fuel burn: 193.0 gal / 1157.7 lb
Estimated time en route: 1:39

My Estimate
454.4 Nautical Miles / 265 MPH Airspeed = 1.72 Hrs
1.72 Hrs * 54 GPH = 92.6 gallon Fuel burn
add : startup, taxi, take-off, landed taxi
estimate: 120 gallons


cruise measurement #1: (after climb)
N39° 6.44' E123° 41.39'
altitude 19750
throttle 68%
manifold 34.6
propeller (RPM) 66%
tachometer 2524
55 GPH
airspeed 265mph
groundspeed 355mph
96 gallons remaining, range 355 miles

cruise measurement #2: (mid-flight)
N38° 59.51' E120° 50.07'
altitude 18269
throttle 68%
manifold 34.6
propeller (RPM) 66%
tachometer 2524
55 GPH
airspeed 266mph
groundspeed 349mph
75gallons remaining, range 479 miles

cruise measurement #3: (before decent)
N39° 2.99' E117° 56.09'
altitude 17515
throttle 68%
manifold 34.6
propeller (RPM) 66%
tachometer 2524
55 GPH
airspeed 268mph
groundspeed 348mph
53 gallons remaining, range 348 miles


Landed with 40 gallons remaining

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