Fuel Efficiency and Calculations?

[Zadren]

Harrier fuel load is pretty small, and she's a thirsty girl. What is the most fuel efficient altitude/speed to transit to the target area/RTB?

 

Also, are there standard calculations one can do to figure out:

 

 

1) How much fuel I need for a particular trip.

2) The best/most efficient flight regime for a particular trip.

3) What I should set as bingo fuel to get home again.

 

I guess all of the above queries apply equally to all the aircraft, but it seems that you really have to pay attention to it in the Harrier - especially since I'm too much of a noob to refuel in flight currently.

 

Cheers :)

[rider11]

Many factors! I am going to do some calcs tonight by flying fully loaded with my Take off weight around 90 and fly 100% power for 15 minutes, 85, 75, and 65 and see what I determine. It will be a low wind, fixed 10K altitude flight.

[Flamin_Squirrel]

The AV-8B has a cruise MFD page that gives optimum levels and speeds to fly at. This will be very useful when it's implemented.

[Eldur]

I think the high altitude fuel flow has to be tuned, similar to the Mirage 2kC when it came out in EA. But you should try watching the FF ppm gauge. It's possible to cruise at quite high speeds with just ~100 ppm, with external stores FF up to 150 ppm should be sufficient. Best altitude depends on loadout, but I'd say it's somewhere between 15kft (heavy load) and 30kft (clean). 100 ppm is 100 lb per minute. Full fuel is approx. 7500 lb, so you can fly for 75 minutes with that fuel flow. Try to imagine there's an afterburner. I've seen values as high as 390 ppm at full throttle. This would drain the whole tank in less than 20 minutes.

[willzah1313]

Whats our ferry range supposed to be with this particular variant? Wiki says 1800nm... 15000lbs of fuel at near 400kts tas at 22-25k 100ppm FF, I was coming up with 2.5 hr endurance and 1000nm, but im sure if I drop tanks as soon as they are empty that would go up quite a bit, but maybe not to 1800nm..... all rough estimations BTW so I could be off

Edited December 4, 2017 by willzah1313

[Flamin_Squirrel]

You'll probably need to climb as the fuel burns off too.

[Zarma]

Carefull because after refuel, when L and R are bugged on 0, the fuel flow is double as indicated on the fuel flow gauge.

[Knock-Knock]

Fuel consumption

 

Is the fuel consumption correct currently?

I find it goes trough its fuel quite fast, so tonight I was monitoring the 'FF PPM' on the engine indicator panel. Im assuming that is Fuel Flow Pound Per Minute? I was flying with that on 100, and was then keeping an eye on the fuel quantity, which ticked down much faster than 100 Pounds per Minute. More like 300 PPM.

 

Or am I getting all this very wrong?

 

Meh crap. Didnt see this thread, when searching for fuel related questions.

https://forums.eagle.ru/showthread.php?t=197153

 

So please just merge mine with that or delete all together.

Edited December 4, 2017 by Knock-Knock

[BIGNEWY]

merged

[Ramsay]

Whats our ferry range supposed to be with this particular variant? Wiki says 1800nm... 15000lbs of fuel at near 400kts tas at 22-25k 100ppm FF, I was coming up with 2.5 hr endurance and 1000nm, but im sure if I drop tanks as soon as they are empty that would go up quite a bit, but maybe not to 1800nm..... all rough estimations BTW so I could be off

The AV-8B SAC Oct 1986, Ferry mission gives:

 

- 4* 300 gallon tanks = 7,915 + 7,915 lb = 15,830 lb

- takeoff weight = 30,604 lb

- Average Cruising Speed TAS = 398 knot

- Cruise Altitude initial/final = 26,050 ft / 40,450 ft

 

- Range 1778 NM (2135 NM if tanks dropped)

- Mission Time 4.48 hours (4.98 if tanks dropped)

 

- Landing weight 15,719 lb

- Fuel 1,205 lb

 

However it's based off the -406 engine and I think Razbam have given us the more powerful -408 engine.

Edited December 5, 2017 by Ramsay

[Zadren]

Thanks all. Now I found the fuel flow meter, it's made it a lot easier. :doh:

 

<100 ppm at 30k ft, at about 400 kts. It really drinks it though when you dive down low to make a run - I guess I'll have to bite the bullet and conquer the tanker.

[Eldur]

Yesterday I noticed a very high consumption rate. FF was 099 PPM, but it burnt 100 lbs in ~30 seconds. Doesn't always seem to be the case though. Usually after landing and "RRing".