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Spare Fuel in the Back

On Patrol

BENEFACTOR
Wentworth NH" The WAD" NH96
My first posting... I just purchased a 56 SC on floats in Wisconsin and need to get her home to Maine. I am both new to cubs and newer yet to floats. In using the SPA guide it looks like I have a 335n.m. trip out of Bay City Mi. to New York where I can land on water and get 100LL. My float instructor has advised taking 6-12 gallons in the back so that I can land and add on the way. I purchased 3 of these small 2 gal. gas jugs that are ventless. I am concerned of pressure building up in the jugs at altitude and popping 100LL all over the cabin. Any Suggestions? Thanks John
 
John,

When we flew the Trench in BC coming and going to Anchorage we had two fives (plastic cans don't know if they were vented, I'll have to check) in the baggage so we could stop halfway and top off. Got up to 5-6,000 MSL and no problems. How high do you have to go on your trip?
 
The only time I use the vents on a fuel can is when I'm pouring it out. When I'm carrying them, the vents are closed tight. Temperature will be a bigger issue than altitude. Gas from an underground fuel tank is cool. The gas in the cans on a hot afternoon will have expanded. The expansion is even worse when the cans are empty. I've had empties puffed up like balloons and never had one fail.

SB
 
Fuel in the back

I anticipate flying at 5000 feet so that I can stay in touch with controllers due to overflying Canadian airspace. I recently flew out to see the SC before purchase. I had a tupperware style container that blew the lid off at 5000 feet. It was small and empty. This is what has me concerned. I plan to ask some further questions in this forum concerning upgrading my poor shape 4" wheels that have not been on the SC in 12 years and are missing parts. I have had some Bush flying with Andover flight and am considering going up to 26" Tundras. Any thoughts on how I should economically start from scratch including tailwheel. Thanks for your help John.
 
About 11 or 12 years ago, I started flying to Cub from Dallas to Baja California pretty frequently. The Mexican drug enforcement people were trenching runways all along the coast to discourage drug runners from landing. Several of the places that sold fuel were shut down for a while, and I found that I couldn't make it from Mexicali to Mulage non-stop with the prevailing SW winds. Found the ideal size: Rubbermaid makes a 2-1/2 Gal. plastic container, and two of them sit perfectly, side-by-side, in the baggage area. I would just land on the beach, and fill up. Never any problem, even in the 100 plus temps. Lucky I didn't get shot, though!
 
The pressure in an un-vented can is a combination of atmospheric pressure, (when your altitude increases), the vapor pressure from the gas, and the expansion of the fuel volume itself as it warms. Combined, this can put a lot of pressure on the jug but that said, I have never heard of one failing. The incident with the Tupperware container is not comparable. Its lid does not screw on securely. I would never have the vent open on a vented container of fuel inside an aircraft. If the container tips over or even turbulence could result in fuel in the cabin, which could be very dangerous. 6 extra gallons is not much considering what you will burn in landing, taxiing, take-off and climb to altitude (5,000 feet?). Traveling west to east is usually with the prevailing winds, which will be in you favor and can increase you ground speed considerably. Depending on your engine you could also buy auto fuel at a marina in a pinch. Make sure you have a good filter funnel. Be careful with an airplane you are not familiar with and don?t know its speeds and fuel burn rates. A couple of 5 gallon fuel jugs can be a float plane pilots best friend.
 
Fill the fuel container(s) to leave as little air as possible below the vent cap level. Then squeeze the container with your knees, to remove as much of the remaining air as possible, and then tighen down the neck top and vent fitting. Load them up and go. I regularily carried 8 or 9 x 5 gallon cans where the back seat is supposed to be in my UTVA 66's with never a problem. I am more fearful of carrying the empty fume filled cans than carrying the full ones!

Cheers,
Wayne
 
spare fuel in the back

making a trip from anchorage to n.m. with two 5 gal. plastic jugs,with no problems,and both are non-vented.


jr. & j.d.
 
Who makes unvented containers?
If they aren't vented, how do you get the gas to pour out?
SB
 
Stewart,

Go to Fred Meyer's. Virtually all the plastic cans you can buy now are "self venting", meaning they vent through the pour spout.

Which is to say, in a nice way, that they actually suck, rather than pour.

My experience is the same as several of these folks.

Remember that liquids don't expand or compress like gases do. If your can is full, the volume of trapped gas is small, so the expansion/contraction is very small and the gas itself doesnt expand/contract enough to notice.

On the other hand, climb and descend with those same cans empty, and they'll expand and contract quite a lot. As someone else noted, I try to keep them in a float compartment, certainly when empty, cause they'll vent some vapors. Full thats' not a problem.

Try taking one of the plastic water bottles in teh cockpit with you, full. Go up, nothing happens, come down, same. Now drink the water, and do the same. The bottle will seriously change shape.

It's just physics.

I've carried literally thousands of gallons of gas that way over the years, and never had a problem.

MTV
 
Remember that liquids don't expand or compress like gases do. If your can is full, the volume of trapped gas is small, so the expansion/contraction is very small and the gas itself doesnt expand/contract enough to notice.

Okay, I gotta weigh in here. Liquids most certainly DO expand and contract - with temperature. Try pumping fuel from a tank farm that is at -40 into a day tank in a building that is 80 degrees. Close all the valves. Fuel will be on the floor in no time. I've seen liquid ammonia trapped between two valves actually rupture a piece of 1" schedule 80 pipe when it warmed up about ten degrees. (and then I ran away!). It isn't as much of a factor in small amounts such as a gas can, but there is a real good reason why you don't fill storage tanks over about 90 per cent.

Of course I agree with you about filling jerry cans to the brim, though. Expanding fuel vapors are usually what makes the mess, since they expand at a much higher rate. . .

Sorry for the nit-pikkin, but I had to say something . . .
:wink:
 
I have four unvented 5 gallon cans I bought at lowes for $5.00 each. The only downside is that they don't fit in the float locker, but that is why I have a belly pod...

sj
 
Moneyburner,

Sorry I wasn't specific enough. My statement was that liquids don't expand and contract the same way gases do. The point I was trying to make was that they don't expand and contract at the same RATE that gases do. I just didn't state it clearly enough.

Obviously, liquids DO expand and contract, but the percentage gain in volume is miniscule compared to gases which incur the same pressure or temperature changes.

MTV
 
fuel cans

I flew my pa-18 from upstate NY to GRR on straight floats..
had 6 - 2.5 gal cans that fit nicely in the float compartment. when I was down to about 1 hr in the tanks I filled from the cans. On Lake Erie. Then walked from the beach to the marina and filled them back up. took a little time but the extra fuel was cheap insurance.
 
If you have hatches on those floats, you have great place for fuel. I used to buy coleman 5 gallon collapsible water jugs and fill them with gas and they would fit through the hatch (duct tape the spout in the closed position). I operated that way for several years and never had a problem with the gas eating through them, but I never stored it in them for more than a a couple of days.
 
Gas In The Back

Thanks for all your suggestions. The Super Cub has a pair of EDO 2000 on it without any lockers. It appears that I have to carry the fuel inside in the baggage compartment or on the rear seat. It looks like I will be solo for my long cross country. In looking at the map I think my route will be Bay City Mi. to Skaneatles NY. I have left the option to land in an enclosed lake (Silver Lake) in Geneseo NY at a long leg of 270 nm. From what I have been told I should estimate a burn on the 160 at 8gph and 100nm per hour. Does any one differ with these stats. Thanks John
 
Fuel burn sounds OK but I think you'll be looking more at 90mph on floats. How close am I guys?
 
I agree with 8 gph, but 100 nmph is pretty optimistic. As noted previously, I'd plan on no more than 90.

If you go faster, you'll be happy.
MTV
 
This may sound goofy but don't forget there is a difference between Knots and Miles. Pretty big difference between 100 kph and 100 Mph. I would plan on 90 Mph. Respectfully submitted.

Bill
 
I'm not aware of any float plane facilities at Skaneateles or Silver Lake. At best, it's a long walk to 100LL at Skaneateles and a long drive from Silver Lake. I don't know what arrangements you may have made, but if I can help give me a call. I live in the area and, except for Oshkosh week, I should be available. (585-265-9596)
 
spare fuel in the back

hey mike
what about a 2 gallon empty glass jug that is tightly closed and taken to 10,000 feet. no expansion !
johnny
 
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