Filling with fuel right to the top?
 

I know this is a silly question, but I genuinely am not sure....

In an R-22, the volume of usable fuel in the tanks are 73Ltr(91.2 usG) and 40Ltr (10.5usG)

What I want to know is, does the tank have to be filled right to the brim close to overflowing to make use of that?.... Or is there some allowable air gap at the top?


What airgap should there be above the fuel?

Obviously appropriate weight and balance calcs have to be made for that much fuel....but....Im curious all the same,


And, I have always been told to do endurance calculations on a burn or 10Gallons per hour.... Is this reasonable or am I way out? I know some people use 8GPH.... What is more accurate?

for the Beta with the 320 donk plan on 32 liters and you SHOULD be pleasantly surprised, as long as you only pull max continuous as per the book.

With mine I can peg it at 28.2 all day every day during mustering during the cooler times.

With the Beta 11 and the 360 donk be prepared for any surprise even if you plan at 38 liters. It depends on the carby fit, how you hold your mouth, the prevailing temperament of your chick, even if the sun is shining, things can go haywire.

28.2 is really good for the clients, who pay for the fuel, and, don't pull over the red line, it plays havoc with endurance, the bosses temperament, and other things.

Just a little tip with different temps and normally aspirated donks.

The old '47G5 used to have a total endurance (to MT) of four hours fifteen on a 22 to 25 Degrees C very dry day with winds running at 18 to 25 knots. (spare energy of the bonus type)

On the hot days of 38 to 40 degrees C no wind and a bit of humidity around it was three hours ten and silence.

In other words the endurance used to vary by well more than the old times legal reserve requirements. Nowadays the rules stipulate that the operator must set their own standards, no need to wonder why they changed the rules.

The fuel quantity is usually determined with the tanks full to the top, just over brimming. Unusable fuel is determined by flying until the engine quits. then draining the remainder. Unusable fuel in the stuff below zero on the gage, but is included in the empty weight of the aircraft as "trapped fluids"

Regarding fuel consumption rates, use the flight manual, and check by topping off at the beginning and end of flights, recording the fuel bowser meter reading (they are quite accurate!)

Topendtorque's mysterious lesser fuel burn on hot days is easy enough to explain - on hot days the engine produces less power, and the engine burns fuel to make power. Less power, less fuel burn rate!

As for the airgap at the top, the folks at the FAA took care of that for you by mandating a minimum amount (2%) I believe.

I think the actual fuel burn is closer to 7GPH but during my X-country flights when I was at school I used 9GPH for my calculations. Some people use 8, but with 9 you will be pretty much assured to have a nice comfortable little reserve at the end of a flight on top of what your supposed to have by the FARs/JARs.

I use 10Gallons for the Beta II
and 9 Gallons for the Beta.
But it varys between the different R22's

If you are calculating endurance for a x-country make an allowance for warming up and leaving the airfield. We always filled to brimming-the 2% air gap would be there by the time you were airbourne. :ok:

There is no 2% gap, extra or magical surplus. The tank volume is measured to the brim, and the minimum fuel is when the engine quits. The stated volume of fuel has NO extra (unlike a car, which typically has a gallon or so as "reserve"), it is your job to figure how to use it properly.

Hi,

when refulling to the brim, don´t forget about a possible slope.
Depending, whether the brim is up- or downslope (even a few degree will have effect) you have some more - or less kg compared to refuelling with the bird standing level.

Greetings Flying Bull

I remember one particular day "somewhere in Northern Australyia", where I sprung a pilot putting two six by four planks on the refuelling pad and then landing his '47 with the front of the skids on the planks.

In response to the question, 'what gives Foot?'

The drawled and rather slow response was, "Waalll I'm flyin' to Queensland and seein' as how it's such a long way, I thort I'd fill 'er up with the hungy boards."

Yep, Queensland was (is) indeed a long ways back, so no further questions were issued. I believe the culprit is now somewhere in Sydney, perhaps having found the, 'far side'.??:ok:

TET,

Ya must be an old Ba@tard if ya know Foot! Specially back in them days.