View Single Post
Old 06-25-2019, 02:11 PM
  #3  
RachelM
New Hire
 
Joined APC: Jun 2019
Posts: 7
Default

Originally Posted by JohnBurke View Post
Rachel,

Clearly you're not flying this aircraft or you'd have this information available. Are you writing an article?

Any time someone asks the a variation of the question about wanting to know about flying (but not landing), you may be able to see the implication. What's the purpose?

A fuel calculation is done using the fuel charts in the aircraft flight manual, and will take into account cruise altitude and weight. For most aircraft, temperature, as well. Fuel and time to climb to altitude is calculated separately, as is time, distance, and fuel burn to descend, and there is a fuel value used for taxi time.

When you ask about a Cessna Super Cargomaster, are you referring to the Cessna Grand Caravan? If so, your estimate of takeoff weight is off by a bit. You mentioned a takeoff weight of 42,000 lbs. The Cessna 208B "Super Cargomaster" has a gross weight of 8,750 lbs, and a relatively small engine. As a turboprop, fuel is calculated in either gallons per hour, or typically pounds of fuel burn per hour.

There isn't really a miles per gallon calculation, though there's something similar called "specific fuel consumption." It's typically not used for something like the Caravan. When calculating fuel burn, the groundspeed with forecast wind at the planned cruise altitude is calculated, then the fuel burn in pounds per hour calculated, then the enroute fuel burn based on pounds per hour over the duration of the cruise time. Obviously for a headwind, cruise time is greater, hence greater fuel burn.

Fuel burn, depending on power setting, will average 60-80 gallons per hour overall. Figure that at 6.7 lbs/gallon for turbine fuel, at 400-540 lbs/hour.

90 nautical mile trip, still air, figure 170 knot cruise speed, approx 35 minute trip. Fuel burn of 70 gph trip average for roughly 42 gallons, plus time to an alternate, using the same number, total of 84 gallons. Figure 45 minutes reserve after that at 55 gallons (rounded off slightly) for a trip minimum fuel of 140 gallons, or 940 lbs.

If you fill the tanks unnecessarily, you'll be carrying less cargo. Bear in mind that the Super Caravan is restricted to a lesser weight in icing conditions, and a higher fuel burn may be needed in the event of an icing encounter.
Hello John,

Thanks for the response. I'm looking to eventually purchase for business usage, if manageable. Currently, I'm researching to determine the best-suited carrier for express cargo purpose. I'm putting together an itemized budget for the cost of the approximate operation of the aircraft, prior to expressing interest, and fuel consumption will be a part of that budget. I apologize if unclear, the cities which we will deliver will be 98nm X2 and 261nm X2.

Interesting, the plane is a Cessna 208B, and the numbers cited were taken directly from the listing. I've heard this is an excellent choice for feeder type operations. Is that correct?

Thank you for showing the determination. It gives me a bit of relief to understand how this is done. I currently have not hired a Pilot to help with this side of things so it's much appreciated.

Best wishes!
RachelM is offline