How do I calculate bingo fuel (or even required fuel) in the Mirage 2000

[Mukai92]

Hey guys, I never really calculated the required fuel for a mission before and just often left the bingo fuel level at default. However I've noticed that with 2.5 in particular, I've been flying longer missions just to look at the scenery before engaging and I don't know how much fuel I should bring and when i should break from the fight and head for home.

 

So how do you calculate the bingo fuel level? And required fuel for a mission?

 

Thanks guys, loving the mirage and the harrier! :)

[Frederf]

Exact bingo calculations would require performance documentation that outlines fuel flow to be expected for the planned altitude, speed profile to be flown as well as corrections for wind, temperature.

 

Normal fuel requirement is to fly from present position through the remainder of the flight plan including bypassing the landing airfield to an alternate plus some set reserve. As such there is no one single bingo value but a bingo for every moment along the flight plan. Infinitely many is too many so the pilot may calculate a fuel reserve required at every waypoint. Perhaps surprisingly it's possible to reach bingo state with much fuel while still on the ground or shortly after takeoff.

 

There is also the concept of a fuel reserve required to safely recover by a method other than the flight plan, e.g. a direct high altitude flight at maximum efficiency. This value will be equal or lower to your flight plan bingo at each moment. There exists a point along the flight plan, usually furthest away, that requires the most fuel to recover using an efficient profile. One might call that the "critical point" and "critical bingo" because that fuel level when reached will allow a return to base from any point along the flight plan. If the fuel reminder is only set to a single value (and not changed passing every waypoint) then it should be this one.

 

Outside detailed planning relying on charts not available, rough calculations are usually good enough. The most typical is to use a planned fuel flow e.g. 30kg/min and a planned ground speed e.g. 360kt to derive a distance fuel rate. In this case that is 1/6 min/nm x 30 kg/min = 5 kg/nm. The inverse is known as "specific range" or the distance per unit fuel (i.e. 0.2nm/kg). One can then figure a 300nm flight will take 1500kg fuel.

 

Takeoff and climb tends to use a constant amount to get to a certain altitude. I don't know a practical number but perhaps a takeoff and climb to 25kft takes 500kg over a distance of 50nm. A more detailed fuel plan would shorten the cruise distance by 50nm and add the takeoff and climb amount.