Fuel Flow/Burn
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@melon Unfortunately some parts of SimBrief at a black box, profiles like that included. As far as I'm aware users can't change or add those profiles, and I made an OFP with the High Speed climb and Descent profiles and didn't get anything helpful for figuring out what my speeds should be.
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@dreadnought1906 Indeed, same annoying behavior. Engine N1 increases as we build up more speed, therefore generating more thrust, but without drag increase, meaning the speed just tend to increase slowly but exponentially if we do not find the exact sweet spot where speed is stable.
It is hard if not impossible to be accurate with speed between 250 and 300KIAS. As long as I am in that range, I don't touch the throttle otherwise it'll either slow down to 200 or overspeed lol
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@plhought The new profile at least for the -100 variant, is better, but not by much.
On my most recent flight from KDAL to KLEX with 50 pax, no cargo, at FL270:
Old Simbrief (B463 profile with adjusted weights to work with -100) Trip Fuel : 9052 lbs
New B461 profile Trip Fuel: 8476 lbs
Actual fuel used: (Gate to gate): 5452 lbsSo still way off, and frankly I think the Simbrief profile is not the problem - the sim is. If the sim's fuel burn is accurate, that means the -100 has around 3,500 nm effective range. I don't f'ing think so.
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@dreadnought1906 Guys, I found a trick that seems to solve the problem of trying to micro-control your throttle lever at cruise.
Set the TMS to TGT (target) mode, and enter 600 in the TGT window. The system will try to maintain all engines at that power setting. I found that 600 results in a cruise speed somewhere between 255 and 260 KIAS. And it's pretty stable. I'm lightly loaded and have to experiment with higher settings, but this is a nice discovery for me.
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@dreadnought1906 Another Simbrief performance reference:
Flight from KEUG to CYVR. Simbrief ordered 34,000 feet, so that's what I did. Can the -100 really fly that high? Anyway...
Simbrief Trip Fuel: 4973 lbs, plus 500 for Taxi
Actual: 3057 lbs Gate-to-gate, including 461 for taxi, so 2596 flight usage.
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@dreadnought1906 this is a genius solution. I’ll give it a try. Thank you.
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@dreadnought1906 Simbrief is weird. It likes to order me to the service ceiling of basically everything I fly, including this at 30,000ft. The pressurization panel won't let me set much above 29,000, if that, so I've been doing FL280.
I wonder if our fuel burns are off in the plane, though. I keep setting 840 as the TGT in the TMS but I never get anywhere near it, even with wide open throttles.
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@dreadnought1906 this solution unfortunately doesn't always work - in the lower flight levels in colder-than-ISA conditions, the 600 (lowest possible value) will still bring you to overspeed.
Something is definitely wrong in the flight model...
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I've just been using 820 TGT, which is what it defaults too. Where does it say to use 840? I know in the tutorial video he used that.
And yeah, that new profile it's been wanting me to fly at 31000 the last couple flights but you can't put the cabin that high, and the plane kind of struggles to reach that altitude anyway. 26-28,000 seem ideal.
Off the top of my head I think at cruise my TGT has been like 650 or so??
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@melon between the manual and the video it says 840. I've been trying to find a guide to setting it anywhere, all I can find is that 840 because it's down from the max continuous value of 857, but like I said I don't even think I break 800 at any point.
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My last flight I was showing a Turbine Gas Temperature of about 650 in cruise.
You can dial in a new value via the thumb wheel to fine tune your speed. Only adjust the 10’s digit though as moving the hundreds digit will kick you off of TGT mode (you can re-enable it) -
So far, flying Adelaide to Sydney, with a TGT set to 645 I've been holding Mach .72 pretty solid at FL280 (1hr 10min so far). I easily reached 840 on take off as well, I don't think that has been a problem for me so far afaik (previously had been using 820).
Started with 7060kg of fuel, each engine is burning about 300kg/hr in cruise, burned 2500kg of fuel total according to the planes own gauges, leaving 4511 in the tanks afterwards. So there is definitely some discrepancy with its accuracy in the plane itself, but I figure that is because of the gauge style. Still According to this I should be able to fly back to Adelaide and nearly back to Sydney again, 1800nm total (and this isn't even with a full tank, a full tank is like 9400kg). So it does seem like the numbers a little bit on the low side? Since bad napkin math would put the range at about 2500nm. TBF, I had an average tailwind of like 40knots which would change these numbers a bit, but not that much surely?
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@melon said in Fuel Flow/Burn:
So there is definitely some discrepancy with its accuracy in the plane itself, but I figure that is because of the gauge style.
We've confirmed it in a few other places but yes, the fuel burn (particularly in cruise) and TGTs are currently too low and we're working to address that.
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Typical fuel consumption for BAe 146 during cruise is 2000 kg/h.
To achieve this, simply increase the fuel_flow_scalar value in the engine.cfg file. Standard value is 0.85
I changed it to 1.15 which makes the fuel consumption pretty realistic and in line with the calculations by SimBrief.[GENERALENGINEDATA]
engine_type =1
fuel_flow_scalar= 1.15
min_throttle_limit=-0.21 -
@melon said in Fuel Flow/Burn:
What do the profile options mean?
I found this in a Mahan Air SOP for the BAE146/RJ
4. CLIMB Three climb techniques are recommended: 4.1.1 High Speed Climb (HSC): 280 IAS or 0.60 IMN. Coincident at approximately FL 190. 4.1.2 Long Range Climb (LRC): 250 IAS or 0.60 IMN, coincident at approximately FL 240. 4.1.3 Steep Gradient Climb: 220 KTS (146‐300).This technique can be used to reach a level or altitude by a particular point. For absolute max gradient performance, climb at VER (VFTO +10). Set climb thrust as soon as convenient (observe maximum 5 minutes) after flaps retraction, or at the thrust reduction altitude for the noise abatement procedure. [...] 6.5 DESCENT SPEED SCHEDULE: Two descent profiles are published: 1‐ Long Range 0.6M/250 kt 2‐ High Speed 0.7M/290 kt In practice, any combination of speeds can be used but ATC may require high forward speed to help fit the relatively slow BAe146 into the arrival flow with other, faster jets. For this reason the high speed profile is favored by many operators. Remember, to observe speed limit points and the limitation of 250 kts below 10 000 ft.As for TGT setting, the same SOP has
The normal power climb setting is 840 ºC TGT, although lower TGT may be used to conserve engine life if high climb performance is not required , (i.e.820 ºC) . -
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@b3lt3r They mean that 250 KIAS will equal Mach 0.6 at approximately FL240 etc. So if you were climbing at 250 KIAS then you could switch from IAS to MACH hold mode passing through approximatively FL240, and vice versa on the descent.
