On 8-Feb-2006, John Theune wrote:

I'd really like to see some number to support your conclusion. By my
estimates 100 hrs * 11 gals per hour = 1100 gal per year. RG decreases
fuel need by 5% or 55 gal * $3.50 = 192.50 per year in fuel savings.
From the numbers throw about by my aircraft owning buddies the delta in
ownership costs for a retract are much more then that.

Assumptions in above: Fuel burn is about the same for 180HP engines in
Comanche 180 and 172s with 180HP engine. Increased speed reduces need
for fuel by 5% by higher speed in cruise, climb fuel burn is the same.
Big YMMV is added


I said "RG compared to a FG WITH SIMILAR PERFORMANCE..." For comparison to
an Arrow or Sierra than burns about 10.5 GPH at 75%, that would be something
like a Skylane or Dakota that burns about 3 GPH more. For 100 hrs, that's
300 gallons, or well over $1000 at today's fuel prices.
Additional maintenance costs for an RG will probably run about $300/yr.
(This is based upon my experience and what my A&P told me.) Insurance
difference could be wildly variable depending upon pilot experience and IR
status, In my case, the extra premium for RG runs about $500/yr.
In other words, the cost of folding the gear is more than offset by the cost
of the fuel needed to drag it through the air.

-Elliott Drucker