Fuel flow error?

[Den Dee]

I've been puzzled by this for some time, so I thought I'd ask. Maybe there is a simple answer to this that I am missing?

I take off in a C208B and climb. Fuel flow at climb a bit below 400pph on the dial. I climb to 12.000 and cruise. Check in-flight report. FSP
reports waay over 400 lbs per hour?! I cruise at 300pph for 3 hours and the average lazily climbs down to 390 lbs per hour where it stays
till descent.

What's up with pph on my flow meter being totally different from lbs per hour in FPS? Does it have something to do with fuel density?
Type of fuel? I am a bit at a loss here...

Flight Distance:...............541 Nm........Landing Speed:..............91.94 kt
Time Airborne:.................02h51:45.....Landing Touchdown:....-153.08 ft/m (nice)
Flight Time (block):.........02h57:31.....Landing Pitch:................0.08°
Time On Ground:............00h11:06.....Landing Weight:.............7744 lbs
Average Speed:...............189.08 kt.....Total Fuel Used:.............1042 lbs
Max. Altitude:....................12057ft.........Fuel Not Used:...............168 lbs
Climb Time:.....................00h07:12.....Climb Fuel Used:...........72 lbs
Cruise Time:....................02h31:08.....Cruise Fuel Used:.........934 lbs
Average Cruise Speed:..198.92 kt.....Cruise fuel/hour:.............370 lbs (calc)
Descent Time:.................00h13:25.....Descent Fuel Used:.......35 lbs


P.S. Sorry, was in wrong forum. Thank you Mr. moderator

Oh, and also: how do i post my copy/pasted flight reports so that they don't look ugly when posted :?



Post Edited ( 07-05-08 20:19 )

[SkyAirWorld]

Screenshots? there probably a better way, or exporting it in a word document or Excel document, and pasting that... lol

Also FSP does work that out roughly, I dont think it is exactly correct, or maybe I'm wrong....

[MonsterCheese]

It takes an average for ALLLLLLL the flight.
Including take-off, hence why I never trust "fuel will allow... travel time" as it's taken into account the take-off and climb which is high.

[Den Dee]

My flow was hardly ever above 400, not on T/O, not in climb...

I can almost swear I read somewhere it'sa got to do with fuel type or density, but for the life of me I cannot find the darn post : (

P.S. Just flew another flight, this time monitoring flow very carefully in all stages of flight. This time the average was more believable. Guess I made some incorrect observations before... Silly me : )



Post Edited ( 07-07-08 12:09 )

[Den Dee]

...Or not. Had my scariest flight with FSPax to date. Taking off from Mogadisho, had my engine shot out about 15 seconds after clearing
the runway. 18% risk warzone, it's a miracle it didn't happen on previous flights. Did a 180 and almost made it back to the runway, landed
about 20m short and ended the roll on the runway. FSP was very happy : )

Then I look at the numbers... average fuel flow... 570+ pph?? That's after taxiing at 200pph for 5 minutes and taking off at 450pph for
about a minute. Leave alone the fact that my FF indicators scale ends at 500pph (and the engine cannot suck in more than 460-470
anyway)...

Has this been just a statistic, fine. But it has a direct impact on the fuel reserve penalty (which one can't even disable... correct?), which is
why it bugs me so.

[Joeflyer]

Den, I hardly look at the fuel flow per hour until I'm at cruise level for a while. Are you saying that you received a penalty for not having
enough reserves during an emergency situation? That certainly doesn't sound right...especially during an emergency.

When I fly the C208 in real time, I typically cruise the bird(depending on altitude and OAT) at 1500 lbs of torque and 300 pph or less. Of
course each aircraft I have flown yields different power settings for the 600shp and 675shp engines. I rarely climb above 10,000 ft.
anyway...unless of course wx conditions , winds aloft and distance of flight are favorable for that decision. At any rate, the Feelthere
developer for the C208 did a fairly decent job of emulating the actual C208 on power parameters and ITT at various altitudes and OAT.
Actually, I need to reinstall that airplane. I keep forgetting to do so

[Den Dee]

Thank you for the reply Sir Joe : )

No, I didn't recieve a reserves penalty for that emergency (and how could I, with tanks full? But I'm happy I managed to land without
fireworks : ) I do receive reserve penalties regularly though, since every dollar matters, and I calculate my fuel as precisely as I can. I go
for (300pph x flight time)+300 (for 1 hour)+ 100lbs for taxi. With weather avoidance sucking into my reserve... well, you know. But I do keep
my sacks of rice safe (I fly cargo exclusively). I've never heard a single complaint from them. FSPax, on the other hand, complains every
now and then and doesn't seem to listen to me saying that I could do another full hour on those 300 lbs I had remaining. That's my main
point of concern.

Here is the rest of the rant, just for the sake of it...

I climb at 300pph if terrain/weather allows, or at 350 if I intend to rise above the weather fast. I set the prop at 1/3 of green range (sorry
can't quite recall the value now... 1700-1800?), then I set the torque to achieve about 300 pph. It comes out at 1500+- 100 lbs torque (my
typical cruise would be 9000, and it would be about +10C there).

I agree Feelthere did an excellent job. I don't even mind the strange stall performance... after all, I try to be a good boy and never stalled
the thing ... except once, and it scared me almost to crash. I lived though : ) It is a shame they discontinued the Caravan : ( But at least I
have it, or rather its shape and flight model, the rest is mine)

I'll check the engine on my feelthere model. Nevertheless, I am positive FSP overestimates the flow at all times. If someone can, please
tell me the type and density of the fuel the real c208 engine uses. Maybe that's just where that error lies.

[Joeflyer]

We use Type I Jet-A in the C208, Sir Den

[Den Dee]

Thank you very much, Sir Joe : ) This is exactly the type of fuel the reports show. So, the error lays elsewhere...

However, It doesn't take too much reserve to defeat that penalty. With me flying in warzones constantly, and the fact that I switched to x2
multiplier recently (after realizing I would not be able to pay for regular inspections), it is only my pilots reputation that is at risk. Now, the
cargo doesn't really care about reputation, so the aforementioned sacks of rice are always waiting at the gate to fill my holds.

Being an infamous pilot who delivers food to starving folk against regulations does not bother me a single bit. In fact, I am looking
forward to my next flight, which will be seriously overweight. I am full of determination and am confident I can deliver this cargo (thankfully,
both the departure and arrival have semi-decent 3000ft+ runways, and they are around MSL (I am currently planning Mombasa-
Mogadisgho).

I regret not posting my fresh shoots (my last flight included going around a huge storm cell, like 10nm across, right above my landing). I'll
do a little touch-up and post them tomorrow : )



Post Edited ( 07-08-08 22:06 )