UAV Propulsion Tech – Post #1 – BSFC Calculation

blog 1 I am starting a weekly blog on the UAV industry and intend to focus my weekly posts on technology, global markets, applications, and industry news.

I am a mechanical engineer and have been working in the UAV business for over 10 years mainly focused on propulsion solutions for defense applications.  I represent several companies providing propulsion, servo/actuators, rescue/recovery parachutes and autopilots into this market.

The format I will start with is to lead with UAV news for the week, then add some technical info on some aspect of UAV’s, list upcoming events and then close with an inspiring quote for the week.  I may adjust this format in the future.

Key UAV News for the week:

Brake Specific Fuel Consumption (BSFC):

BSFC is the measure of fuel efficiency for internal combustion engines.   It is the power specific fuel consumption and is calculated by: fuel consumed (lbs/hr) divided by horsepower.   Typically the fuel consumed is measured in gallons per hour and you can convert this to lbs/hr using the mass of the fuel tested.   UAV’s typically fly on gasoline, jet fuel or diesel fuel.  The mass of these fuels are:

  • Gasoline weighs 6.1 lbs/gal
  • Jet A weighs 6.8 lbs/gal
  • Diesel fuel weighs 7.1 lbs/gal

BSFC is noted in lbs/hp-hr and g/kW-hr.  When an engine is developed for a UAV, the BSFC is typically optimized for the cruise point in order to minimize fuel consumption and maximize endurance.  This is typically 50-75% of WOT depending on the application.  The BSFC calculations at various operating points and information on a typical mission profile can allow the UAV manufacturer to predict fuel burn per mission.

Wikipedia has a good description of BSFC as well as a list comparing various engines.

Optimization of the propulsion system for power, weight, fuel consumption and reliability are key parameters for the UAV developer.

Industry Events this week:

Quote for the week:

“Success is not final, failure is not final: it is the courage to continue that counts” Winston Churchill

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