The average leg length for our flights here in Peru is 1 hour. That means we average one takeoff and one landing per hour, however the average flight is longer than 1 hour as all of our flights are round trip, and roughly 30% of the time they are multiple stop as well. Since here are no airports in the whole Peruvian jungle that sell aviation fuel, we have two options. Carry round trip fuel for our flights (plus 1 hour of reserve) or store fuel in strategic locations for refueling. We take advantage of both these options as dictated by the total flight time and needs of our users. Carrying more fuel on board equates to less weight available for people and cargo. For example, 3 hours of fuel (48 gallons) in the wheel plane gives you 500 kilos or 1100 pounds or useful load. Full fuel (116 gallons) only leaves 315 kilos or 700 pounds of useful load. In the float plane, it is even less because the floats weight almost 300 pounds!
When we do flights over 4 hours in the float plane, we are almost always refueling, some times twice during the same trip. At the remote fuel storage areas, we syphon fuel from 55 gallons drums into 5 gallon plastic containers. These are then carried to the plane and poured through a filter. The 55 gallon drums are usually transported to various locations by boat or by road. The cost to transport fuel like this and stock it in remote locations adds roughly $2-3 dollars more to the price per gallon. When we have the opportunity, we transport the 55 gallons drums inside the airplane. However this is never done when there are passengers onboard. We also have the option of carrying extra fuel in the wings and shyphoning fuel out when we land at the remote location for use at a later time. I have done this a couple of times now, but it is not very common.
For syphoning, we usually use a 1 1/2 inch hose as the flow rate is very quick. Getting the flow started is the hard part, this done by sucking on the hose to get the flow of gas going. It works pretty good most of the time, but once and a while not so much. The worst is getting gas in your mouth. I have had this happen twice, and let me tell you, that was two times to many! We have found some little rattle syphons that use a 1/2 inch hose, they work great and don't require any sucking at all! The only down side is that it takes 3 times as long to fill up the tanks with the smaller hose.
Photo courtesy of Aircraft Spruce.