Gary,
I did abide by the spirit since it specified "your plane". Thus, I
used my operating methods.
'Twas an opportunity to top it up without having to go through the time and
trouble of doing it again soon. After all, filling to "minutes" requires
that you know the TAS, power setting, distance and winds in order to have a best
guess at ground speed (time) and fuel consumption. My next
flight would be computed based on estimated hours and fuel left aboard.
Since I have very accurate tank gauges and fuel flow indication, I don't have to
"stick" the fuel remaining to know how much is there. Carrying the extra
fuel for a short flight (i.e. no climb to altitude - more like a ballistic
arc) did not impose any real penalty. Perhaps I would even do a practice
GPS approach to the target field (plan activated soon after lift-off) to
keep sharp since no additional flight was planned for a few weeks.
I knew I had only about 30 minutes of fuel in my plane because the
wings were empty (bone dry - I can do that in level flight) and the header
gauge reads 6.5 gallons (1 gal est for taxi, takeoff power and not much
climb). BTW, that 30 minutes was at least 45 minutes had I been in the air
at approach speeds so I had legal reserves present on the
last landing. Also, I had to add fuel because I have my plane
placarded to require at least 8 gallons in the header before
takeoff.
The unusable fuel in the header is less than 1 gallon because of the
baffling, sump and ground testing the tank at high pitch
angles. Do you know what the unusable is in your wings during climb or
descent angles? What about when in descending uncoordinated flight
(slip)?
Anyway, I can carry 43 gallons max. Subtract 10 (1 unusable, 1
for taxi/take off, 8 reserve for 1 hr at slightly reduced power), leaving
33 gallons or 3.3 hours at best power, about 10 gph, at moderate altitudes (say
4000 to 7000 MSL).
Grayhawk
PS I am old (hint - see my signature) so I like to stop every 3 1/2
hrs anyway. Comfort is important.
PPS Merry Christmas to all.
In a message dated 12/24/2009 7:53:13 A.M. Central Standard Time,
casey.gary@yahoo.com writes:
Thanks, Rob, for posting the results. The ones that said "top it"
didn't abide by the spirit of the question :-) in that I don't know how many
minutes of fuel that equates to, but there were enough replies in minutes.
The technician in me couldn't resist doing some math:
The average planned fuel remaining was 63 minutes, or about 30 minutes in
each tank. I guess that would work, but for me that would be about 7
gallons in each tank, at my low fuel warning setting. I know I would get
an additional verbal warning from my usual right seat crewmember :-(.
The standard deviation of the answers was 33 minutes, a fairly large
variation considering the average was 63 minutes. A significant number
of people would have in the vicinity of 30 minutes remaining. In fact, 4
out of 12 would have 30 minutes or less. One planned the flight with
only 20 minutes remaining.
Of course, if I knew the minutes remaining of the ones that said "top it"
the results would shift dramatically.
Gary
Thanks to those that responded to the
fuel question. This is how it was
worded:
There is 30min of fuel in
your plane.
You wanta meet your friends for lunch on this stunning VFR
day.
You don't have any planned flights for the next few weeks.
The
lunch stop's gas is the same price as as at your home field.
The lunch
stop's runway is 5,000 at sea level.
The flight time to lunch is
30mins
How many mins of fuel do you add to your tanks for the
flight?
Here is the summery in the form of:
in the plane + personal
min + trip + extra
30 + top
30 + top
30 + top
30 + top
30 +
top
30 + top
30 + top
30 + top
30 + top
30 + top
30 + 30 +
top
30 + 15 + full wings, not aux
30 + 30 + 60 + 60
30 +
120
30 + 120
30 + 120
30 + 120
30 + 30 + 30 + 30
30 + 30 +
60
30 + 30 + 30 + 15
30 + 15 + 30 + 15
30 + 15 + 30 + 5
30 +
0 + 60
30 + 60
common notes:
1) always top
2) add
enough to get to lunch and home plus personal reserve
3) fill to a level
one can directly observe fuel in tank.
Rob