I can't remember all the details but he had a formula that took gallons per hour (Rich of Peak) times price per gallon times a constant and voila you had a pretty close estimate of your cost per flight hour. I think for a retract single the constant was 2.5 to 3.0. For a fixed gear single it was about 2.0 and for a light twin it was better than 3.0.

Jeff,

 

You are right, It worked for my Skymaster clt twin when gas was about $2.20/gal, 20 gph times 3 equaled $132/hr - very close.  However, experimentals require carefully calculated adjustments.

 

Take a retractable single (please) --  Adjust the constant 2.5 as follows:

 

subtract .5314466667 if the builder/repairman maintains the airplane and more than one motorcycle,

 

only subtract .000122257  if the builder/repairman likes "gadgets"

 

add .100067 if you live in Texas or Oklahoma and only do intrastate travel utilizing cheap avgas.

 

add 3.666667 if your airplane is based in an OPEC country not yet invaded by the coalition (cheap gas again) and you actually fly.

 

add .5 if the owner bought the plane and uses a "certified" mechanic (later tool/parts purchases are not yet added in).

 

add 0 if the builder/owner is a "certified" A & P (general practioner, fabric speciality, prior boat owner, has his own roll of safety wire)

 

add 1.5 if the builder/owner did not do the firewall forward work and had the panel built by some cad/cam shop with professional terminal crimpers (ya still gotta drill your own holes later).

 

add 2.0 if the builder/owner is a certified jet mechanic and only knows what "vane" means (no, no, not vein - thats for doctor/pilots).

 

add another 1.0 for those "owners" that have had 3 or more "incidents"

 

There are other positive adjustments (especially for those that have executed their first high key without changing their vocal pitch, use mach numbers for all speed indications, only use straight in approaches, can't remember where the "pitot heat" sw is, etc.).

 

Prop costs must be calculated separately.

 

Note: if I have failed to offend any specific group, please let me know so I can correct that in the future and become more compassionately inclusive.