Fuel Flow Scalar

[martianfrogz]

My favorite plane is the [glb]Beech King Air 350.[/glb] I am currently flying RTW with it, and at the start, I had to make an emergency fuel stop after only flying [glb]384 NM!!!!![/glb] The Beech stats online say the bird has a range of around 1,800 Nm, so I changed the fuel flow scalar from 1.0 to .17 to get it in that ballpark range. Now the fuel guage reads FULL after traveling 1500 nm! How can I fix it to go down realistically? I saw somewhere that if you up the thrust scalar, it will, but I don't know..... TIA Alex

[microlight]

Alex,

The way I did it for my collection of 737s was to set the fuel flow scalar at 1.0 and then fly using real world weather until the tanks were pretty much empty, giving the maximum range. Then by using the published range and making a calculation, I was able to adjust the FFS to make the FS model perform to the published spec. I ended up with figures of between 0.7 and 0.9 depending on 737 series.

0.17 sounds far too low to me - that's more than 5x the distance you can travel with the setting at 1.0! I'd recommend starting at around 0.75 and see what happens.

[ozzy72]

Are you correctly setting the angle of the props and metering the fuel? If you keep the props on fine pitch and the fuel running at full tilt then that is about the maximum range you'll get!

Ozzy

[microlight]

Good point Ozzy! I never fly prop planes so this isn't the first thing I think about!

[ozzy72]

I just remember the first time I flew it in FS I forgot (and me a guy that had gained a PPL) to set the prop to coarse pitch and adjust the fuel. I wanted to do London-Budapest and bombed on the Franco-German border (I hadn't flown for 8 years and my dead-stick landings sucked right up to the point when I crashed into the old ladies kitchen for lunch)

Ozzy

[martianfrogz]

Microlight, you are supposed to get 5x the range than what it was giving me. I think I gave it about 300x longer range.
Ozzy, how do you know how I fly? I guess that's not how you're supposed to fly anyway. Well, I guess I'll fly that way. The only prop I've flown in real life is a Cessna 152 with a fixed pitch prop... well, and an ultralight. Well, I'll try that. Microlight, do you remember the formula you used? If so, could you post it? Thanks! Alex

[microlight]

For an initial FFS of 1.0, it would be:

Reciprocal of published range / actual range x fuel flow scalar.

So if the published plane range is say 2000 miles and you actually fly 3000 miles, the it would be the reciprocal of 2000/3000x1 - in other words 1.49.  So the FFS would then be re-set to 1.49. This means that the plane is now using 1.49x as much fuel and therefore goes 2/3 the distance on it.

You can then test it out to make sure it's accurate. It'll be pretty accurate to two decimal places, which I guess is all you need as real world weather, speed etc. will make any more accuracy almost irrelevant.

[martianfrogz]

Ok, here's how I did it- 1817 Nm published range, 696 actual- 1817 divided by 696 equals 0.38. 0.38x 1=0.38