Gary, Ed, John, all:
Ed: The "Smaller" wing tanks are aluminum replacement tanks of
approximately 8 gallon capacity. They allowed replacement of original
terneplate tanks (installed on airframes through 2622) without cutting
the fuselage skin (necessary to fit the nine gallon production aluminum
tanks). There were NO Ercoupes originally manufactured with the eight
gallon (smaller) aluminum wing tanks.
John,
There were NO 8 gallon terneplate tanks. Prewar airframes with a
single right wing tank held 9 gallons. Postwar Ercoupes ALL carried 18
gallons in the wing tanks when manufactured, as evidenced by the
advertised total fuel capacity of 23 gallons with the earlier five
gallon capacity nose tank.
Gary: To accurately measure wing tank usable fuel, following a flight
mark the fuselage gauge where the fuel transfer pump and overflow
action have it as "Full". Drain the wing tanks and put back in each
about a quart of fuel. Take the ship aloft with:
(1) Small wedge (wood hardware store door shim works fine)
(2) Duct (duck?) tape
(3) A 6-12" level.
Trim the ship for cruise at the speed and RPM you usually use to go
places. Shim the level on the interior window sill so that it
indicated "level" when the ship is trimmed (as above).
You should rather soon see the fuselage tank gauge start to drop.
Level the plan left-right, and block the nose or main gear such that
the level is again reading "level" on the ground. Put two gallons in
each wing tank. Because of the wing dihedral and tank shape, the fuel
gauge may not yet move (if it does, mark it). Put two more gallons in
each wing tank and mark the gauge.
Repeat. Now add one more gallon in each wing tank and alternate left
and right bringing the fuel level to your normal "maximum". You have
now calibrated YOUR wing tanks accurately with YOUR cork floats.
Ed is correct...saturation of cork floats reduces buoyancy and changes
the reading over time. Any time you replace cork floats, calibrate as
described again.
The cap-style gauge corks are different between the nose tank gauge and
the various wing tank gauges. To my knowledge NO tanks, wing or
fuselage, are "marked" as to capacity. The caps are stamped with
capacity, but this can be misleading if nine gallon terneplate tanks
are replace with smaller aluminum ones and the original caps were not
replaced with correctly stamped ones.
Regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
--
On Aug 28, 2009, at 12:09, John Cooper wrote:
Gary:
What type of gauge do you have? If it is in the fuel cap, than the
gauge will bottom out while there is still 3 or so gallons left in
each tank due to the wing dihedral. Your serial number should have
“ternplate” tanks of 8 gallons each with a float at the wing root on
the right hand tank.
John Cooper
Skyport Services
www.skyportservices.net
On Aug 28, 2009, at 11:33, Ed Burkhead wrote:
Gary,
When the experts answer it’ll help them if you include your serial
number. (This is a general rule that applies to all hardware changes
in Coupes.) Changes like wing tank size were done at certain serial
number marks.
Even with the 9-gallon wing tanks, my wing tank gauge still had at
least 3-4 gallons left after the gauge claimed empty. The any
saturation and reduction in buoyancy of the wing tank gauge’s cork
will make this worse.
Ed
On Aug 28, 2009, at 10:57, G. Davis wrote:
I have the smaller wing tanks(7.5 gals I thinnk). I tried to run them
dry yesterday and start using my header tank, which I would land, and
fill the wing tanks to see my useful fuel in my wing tanks. I flew and
flew with the wing gauge flat on bottom, and never did see my header
tank start to go down any. When I filled my wing tanks(it was almost
dark by now), I put in 9.8 gallons. My question is, are there
different cork-gauges for the smaller tanks than the 9 gallon tanks.
My wing tanks are marked 9 gallons, but when I removed one to have it
rebuilt by John Wright, it was the smaller size. Thanks for reading
this.
Gary
