BN2 fuel burn

Hi,

First - Thanks for a great utility.

I created a profile for the BN2 based on the short 360.
I don’t see anywhere to insert fuel burn.
When planning routes I often get “warning flight exceeds aircraft range”.
I note that with the calc includes 400 lbs fuel for 45 min reserve. With only 1008 lbs of fuel capacity, the reserve becomes 40%.
Where does the fuel consumption calc come from, as it can’t be entered by the user?

Thanks again

Stephen

Why would you pick the Short 360 as a base?

The BN2 has:

  • an empty weight of 4,114 lbs
  • a maximum takeoff weight of 6,600 lbs
  • a fuel capacity of 165 US gallons
  • a service ceiling of 13,000 feet
  • can fit up to 9 passengers
  • is powered by “2 × Lycoming O-540-E4C5 6-cylinder air-cooled horizontally-opposed piston engines, 260 hp (190 kW) each”

The Short 360 has:

  • an empty weight of 17,350 lbs (over 4 times that of the BN2)
  • a maximum takeoff weight of 27,099 lbs (over 4 times that of the BN2)
  • a fuel capacity of 576 US gallons (over 3 times that of the BN2)
  • a service ceiling of 20,000 feet
  • can fit up to 39 passengers
  • is powered by “2 × Pratt & Whitney Canada PT6A-65AR turboprop, 1,062 kW (1,424 shp) each”

Thus it’s reasonable to expect the Short 360’s fuel consumption might be over 3 times than of the BN2, making it quite unsuitable as a starting point.

Fuel and performance table for the Short 360, presumably. You can adjust consumption via the Fuel Factor, but the aircraft types are way too different to begin with for this to be practical.

I am not sure what would be a good base for the BN2, just that the Short 360 is not it.

Regards,

Tim

Thanks - I found the Short 360 to be the best match from the list. If you can come up with a better THAT would be helpful.

Regardless of this, as mentioned the calculated fuel consumption for the self adapted airframes - is more or less black box - and what I am trying to get a grip on…

But it’s clearly not, by far. The aircraft kind of look similar (in that way, the BN2 is sort of a miniature Short 360), but that’s not particularly relevant to fuel burn or general aircraft performance.

First, whatever base should be a piston-powered aircraft, not a turboprop (just like you shouldn’t use a jet as a base for a turboprop aircraft, for example).

Then it should be in the same weight range-- the Short 360 is 4 times heavier, so in that way it’s like using a 747 as a base for e.g. a 737 and expecting the fuel burns to be similar.

A good starting point would be to look at the “Aircraft of comparable role, configuration, and era” on the Wikipedia page for the BN2:

The Aero Commander looks most similar in terms of specifications, although sadly there’s no such base on Simbrief either.

After taking a look at the list, as far as I can tell the closest matches would be:

https://www.simbrief.com/home/?page=aircraft&sort=code#aclist

  • Cessna 404 Titan
  • Beechcraft Duke

Both use turbocharged piston engines instead of naturally aspirated and the Duke is pressurized so they’re not close close but better than the Short as a base.

Given that the Simbrief data for the C404 is of unknown origin, I would pick the Duke (BE60). Then of course you need to adjust at least:

  • weights and fuel capacity
  • service ceiling (13 thousand feet instead of 30 thousand)

Eventually (this can only come through testing/trial and error), you may find you need to set an altitude offset as the Duke’s climb performance is probably a fair bit higher than the BN2’s, and one you become familiar with the aircraft’s fuel burn you’ll be able to find a fuel factor that gives you better fuel predictions for the BN2.

Regards,

Tim

Edit: forgot to highlight the service ceiling, bottom right, next to the cruise level offset.

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@SimBrief it might make sense to add some information to the aircraft list somewhere, such as OEW, MTOW, engine count and engine type (piston/turbo piston/turbine/jet), perhaps service ceiling, to help in selecting a base profile for unsupported aircraft (ideally, allowing to sort the list by OEW/MTOW as well)?

I’m not sure where one would find the room for it TBH, but the current situation makes it sometimes difficult/tedious/time-consuming to find a close match for some aircraft.

Regards,

Tim

Some of these details are already listed on the “New Airframe” page:

Maybe we can find a way to show a bit more info, but at least the MTOW, cruise speed and ceiling are already listed and sortable using the column headers.

Best regards,

Ah, indeed :slight_smile:

Although I did have to go make my browser window full screen to see the MTOW column, explains why I never noticed it.

Thanks,

Tim

P.S. I suppose even though it’s a bit on the lighter side, the Cessna 310R might still be a better match than the Duke. The Cessna 337H also has a closer cruise speed to that of the BN2, although the weight differences are more pronounced than with the 310.

In general I would say matching cruise speed is more important than matching weight (within reason), since cruise speed can’t be tweaked at all in SimBrief’s airframe editor. Matching cruise speed also means it’s more likely that climb performance will be similar.

My vote in this case would probably be the C337.

@sodgaard this airframe might suit your needs: BN2P Airframe

Best regards,

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