Plane & Pilot
Friday, July 1, 2005

Saving Money On Fuel

With the price of avgas at record highs, here are some thoughts on getting the most out of your budget

I was told when I bought my first single-engine airplane back in the last century that I could estimate my total hourly operating cost by multiplying fuel expense by three. In those days, I flew a Globe Swift that burned six gallons an hour. Fuel was only about 70 cents per gallon as I remember, so I figured my fuel cost at $4.20 per hour and total cost to operate the Swift at a whopping $13 per hour, an intimidating number in those days." />

There are only three ways to reduce fuel expense (other than giving up flying altogether). One is to make the airplane fly faster on the same amount of fuel; the second is to fly the same speed on less fuel; and the third is to reduce the time en route between point of departure and destination by planning a more efficient flight. Implement all three methods, and you’re almost guaranteed to see a significant reduction in your fuel bill.

Flying faster has been a goal of practically every pilot since the Wrights. No one is suggesting you modify your airplane for speed, but there are a few simple techniques you can employ to improve cruise at essentially no cost.

One guaranteed method of flying faster is simply to reduce weight. The late Roy LoPresti once told me you could expect a 1% cruise improvement on most general aviation singles for every 100 pounds of weight reduction. Just as some folks allow things to accumulate in their car’s trunk, pilots often allow the pile of miscellaneous stuff in an airplane’s baggage compartment to grow beyond all normal limits. I purchased a case of oil a while back, loaded it into my Mooney’s baggage area and let it sit there for a month before finally unloading it into my hangar. You may not be able to find 100 pounds of stuff to off-load, but even 50 pounds will make a difference, perhaps as much as one knot.

It’s also important to place whatever weight you must carry as far aft as possible to move the CG toward the back of the allowable envelope. Any model of a given weight will always fly faster at an aft CG because the tail has to generate less downlift to balance the airplane. This doesn’t mean you should add weight to move the CG aft, though some air racers do exactly that, planting lead shots or weight bars in the tailcone. The benefit of an aft CG can sometimes offset the slight loss of a higher weight.

Other simple tricks that may make your airplane fly faster on the same power include keeping all vents closed if you don’t need them open, keeping the airplane clean and waxed (especially the critical leading edges), making certain rigging is correct at the annual inspection and attending to any minor nicks in the prop. Engine tune obviously needs to be as close to perfect as you can make it to assure you’re developing the power you’re paying for.


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