Playing Tanker

We don?t have fuel at the airpark where we live, so one of the realities of our flying lives is to pick up fuel at neighboring airports in a smart fashion. For instance, local flying hops are sometimes planned to hit a cheap fuel stop on the way home. Other times, we know a trip is coming up, and if it is going to be a long day (and we don?t want a fuel stop in the first few miles) we want to make sure we end up at home with nearly full tanks. At the same time, I am the son of a depression-era parents, and hate paying a penny more than I have to when buying anything ? including Avgas, which we tend to use at a prodigious rate (lots of flying hours?)! As a result, I am frequently asking the question, ?where is the most sensible place to buy fuel today??

This seems like a simple matter ? fly to the nearest airport for gas, or look at Airnav for the cheapest price ? right? Well?maybe. The nearest airport with fuel is 4 miles away, but is generally a dollar a gallon higher than the place 30 miles away. If I am going to go flying ANYWAY, doesn?t it mosey on over to the cheap place and mosey on back? While much of the time, it doesn?t make a real difference (we all know it doesn?t pay to drive across town to save a few cents per gallon, but we hate paying the higher prices!), sometimes, it sure can. The real problem I have is in completely and accurately describing the ?problem? I am trying to solve. Cheapest overall? Most fuel? Best price per gallon based on the amount you have when you get home? The engineer in me wants to quantify everything, but if you can?t accurately describe the question, the answer will be ambiguous.

In an attempt to try and at least clarify the problem, I built a little spreadsheet that considers a flight to go and get 20 gallons of gas. It considers the price at each airport, the distance to the airport, and a set of variables such as fuel burn and ground speed that are held constant for each case. I added up the fuel for the round trip plus the 20 gallons, and produced a ?total gallon? column. Another column is ?Fuel remaining when you Get Home? (of course that is always going to sort with the closest airport at the top). I found that if there was enough difference in fuel prices in the local area, the total fill up cost can vary significantly from the ?nearest to closest? sort. This of course, was just a quick and dirty look at the problem ? I?d be interested to see if anyone else has thoughts on this ?rainy day? problem?.

You can sure tell when the space shuttle is on the ground.



Problem solved...... and you are saving about $1 / gallon by topping off your tanks with 92 Octane mogas. Buy 100ll when you can and where you stop, top the tanks off when you get home. I've pumped over 5,000 gallon of mogas though this 100 gallon tank.

Filling up at your home airport also offers less wear and tear on the plane.

Cans

Paul,

I do much the same thing as you with a trip out for cheap fuel. When I know I have a trip coming up I siphon off 6gal out of each tank using a clear vinyl hose. I fill the hose using the quick drain and then poke one end into the tank and the other into the gas jug on the floor in front of the wing. I then fly oout for my little attitude flight, stop for cheap fuel on the way home and then top off with the 12gal in the jugs. I only use about 3 gal to get home from the fuel stop so I usually have enough fuel left over for a near fill from a short last leg home.

(I never buy fuel at my home airport because they **** and moan about driving the truck up to my hanger for "only" 10 gallons, all the while they are one of the most expensive places in the state to buy 100LL. I save 1.70/g by going elsewhere, I get to fill it myself and I ike to fly!

When economics dictate

like when ethanol free mogas (5 min flight away) is about same price as the watered down stuff in town..Then

I found that 4*5 gallon gas cans fit rather nicely in the bagage area...If I'm by myself I can fit another 2 on the PX seat.

I tie a strap on the on them to stop them sliding around.

Frank

Willing to share your spreadsheet so we dont' have to recreate the wheel? I'd even post it on my web server for others to d/l...

Matthew
[email protected]

Ironflight said:

We don?t have fuel at the airpark where we live, so one of the realities of our flying lives is to pick up fuel at neighboring airports in a smart fashion. For instance, local flying hops are sometimes planned to hit a cheap fuel stop on the way home. Other times, we know a trip is coming up, and if it is going to be a long day (and we don?t want a fuel stop in the first few miles) we want to make sure we end up at home with nearly full tanks. At the same time, I am the son of a depression-era parents, and hate paying a penny more than I have to when buying anything ? including Avgas, which we tend to use at a prodigious rate (lots of flying hours?)! As a result, I am frequently asking the question, ?where is the most sensible place to buy fuel today??

This seems like a simple matter ? fly to the nearest airport for gas, or look at Airnav for the cheapest price ? right? Well?maybe. The nearest airport with fuel is 4 miles away, but is generally a dollar a gallon higher than the place 30 miles away. If I am going to go flying ANYWAY, doesn?t it mosey on over to the cheap place and mosey on back? While much of the time, it doesn?t make a real difference (we all know it doesn?t pay to drive across town to save a few cents per gallon, but we hate paying the higher prices!), sometimes, it sure can. The real problem I have is in completely and accurately describing the ?problem? I am trying to solve. Cheapest overall? Most fuel? Best price per gallon based on the amount you have when you get home? The engineer in me wants to quantify everything, but if you can?t accurately describe the question, the answer will be ambiguous.

In an attempt to try and at least clarify the problem, I built a little spreadsheet that considers a flight to go and get 20 gallons of gas. It considers the price at each airport, the distance to the airport, and a set of variables such as fuel burn and ground speed that are held constant for each case. I added up the fuel for the round trip plus the 20 gallons, and produced a ?total gallon? column. Another column is ?Fuel remaining when you Get Home? (of course that is always going to sort with the closest airport at the top). I found that if there was enough difference in fuel prices in the local area, the total fill up cost can vary significantly from the ?nearest to closest? sort. This of course, was just a quick and dirty look at the problem ? I?d be interested to see if anyone else has thoughts on this ?rainy day? problem?.

Click to expand...

Same boat - same neck of the woods...

I haven't created a cool spreadsheet but then again I do my 'tanker' run to just one airport. T90 (on Paul's list). I calculate that I save $30-$40 on average over my homebase BMT to fly the 12 minute hop and fill up in my -7. I don't include wear and tear on the plane because I wouldn't need the gas if I wasn't going flying anyway

Gsuit said:

I haven't created a cool spreadsheet but then again I do my 'tanker' run to just one airport. T90 (on Paul's list). I calculate that I save $30-$40 on average over my homebase BMT to fly the 12 minute hop and fill up in my -7. I don't include wear and tear on the plane because I wouldn't need the gas if I wasn't going flying anyway

Click to expand...

Watch out - T90 just got expensive! I flew across the bay to Anahuac this morning (has been $2.65/gallon), and while I was on base, the Unicom lady told me the fuel pump was broken. i asked if Winnie was up (she.the County runs them both), and she said "yes", so I thanked her and landed there to fill up. After filling, the receipt said it was $3.65/gallon!

I should have gone to Liberty....(And this was what reminded me to dig out the spreadsheet and start this thread...)

Paul

N523RV said:

Willing to share your spreadsheet so we dont' have to recreate the wheel? I'd even post it on my web server for others to d/l...

Matthew
[email protected]

Click to expand...

I'll email it to you Mathew - it's crude, but works.

Paul

File for download

Here is the file for anyone that would like it.

http://www.n523rv.com/Tanker%20Calculator.xls

Ironflight said:

I'll email it to you Mathew - it's crude, but works.

Paul

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When hauling large amounts of mogas around on a trailer or in the back of a pickup truck, better check local laws to make sure you aren't required to have a special expensive type of tank that is DOT-approved for gasoline and possible also a permit or license to haul more than 50 or 100 gallons that is not dispensed directly into a vehicle's fuel tank from the point of sale. Some of the state laws have become quite onerous in recent years. For example, I think it happened in Florida a couple years ago, where some guy got charged with a felony for using an unapproved transfer tank mounted in the bed of his pickup truck for transporting 100+ gallons of gasoline for his boat. The laws often differentiate between diesel transfer tanks and those that are DOT-approved for gasoline, which are much more expensive. Something about diesel being merely a "combustible" liquid whereas gasoline is "flammable" and it's transportation being more tightly regulated.

I have been through the rationale on the fuel trailer, but it just doesn't work out for me. First, it is not unheard of for Louise and I to go through a hundred gallons in a week. (Transporting more than that at a time is big-time regulated in Texas). We know where we could get a 250 gallon trailer, but getting it here would cost quite a bit in truck gas, and then driving the 30 miles down and back to the closest "cheap fuel" airport would eat up considerably more gas. If I burned MOGAS, it might make more sense, but recouping the cost of set-up and operation wouldn't happen in our lifetime - hence, the topic of the thread on figuring out how to "fly" the cheap fuel in.

We DO keep about 25 gallons of Avgas on hand in cans in our hangar when we want to top off before going somewhere BTW - full tanks at ANY cost are a great safety factor when departing on a long IFR cross-country!

Ironflight said:

If I burned MOGAS, it might make more sense, but recouping the cost of set-up and operation wouldn't happen in our lifetime - hence, the topic of the thread on figuring out how to "fly" the cheap fuel in.

Click to expand...

I have about $700 invested in my trailer including dual filter system, 12V pump, fuel meter, trailer, ect. If you just use it to top your tanks off you won't need but say 20 -30 gallons a week of mogas. I save $1.00 a gallon over 100ll min. At that rate it would take you less than a year to pay for the whole rig, and from there on out your depression era parents would be mighty proud. Savings is savings, and like you said the safety of having full tanks on a CC is a good thing also. And!!!! you don't have to pour the fuel in from heavy cans, you can turn the pump on and measure exactly how much you are putting in.

No problems here using the fuel trailer for over 10 years and it is 100 gallons, I'm pretty sure anything under 100 gallons is okay, in NE anyway. I "farm" also so it is a fuel wagon for my "crop dusters". hehehe

Are there rules at your airpark against having a fuel farm? Tanks & pumps aren't that expensive if you can share the cost with several other owners. IIRC, we got a 1,000 gal tank, pump, long hose, meter, etc, all new stuff, for around $1200 which we split 3 or 4 ways. If you watch local farm publications, you can pick up everything used for much less. I bought 2 tanks (1k gal diesel & 550 gal gas) with gas station style pumps from a retiring farmer a few years ago for a little over $200. With a good water trap & filter, even used tanks are safe to fuel from.

With a fixed tank, we just call the wholesaler & have a load delivered. The wholesale price delivered is typically about the same price as the cheapest to be found in a 150 mile radius and Much cheaper than any of the local airports.

Charlie
(But I still haul premium mogas in 5gal cans because it just runs better in my 160hp O-320. I really need to get one of those tanks set up for mogas....)

rv7charlie said:

Are there rules at your airpark against having a fuel farm?

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Airpark rules? Nope. City of Friendswwod? Well, I have to point out that we are literally in the middle of a major residential, suburban neighborhhod. Our runway is narrower than most of the streets, and we have houses everywhere. At the very least, we'd be regulated the same as a gas station. This is not an edge-of-town, rural environment.

But...this thread is not really about us having/not having gas at our field, or burning Mogas. I KNOW there are lots of folks out there with expensive fuel at their home fields that go elsewhere to gas up. This is about the thought process of "where does it make sense to go?" For instance, if I want the hypothetical 20 gallons of fuel in my hangar, and the very nearby field is charging a dollar a gallon more than the place that costs me $10 to fly to (round trip), then I have saved ten bucks (and gotten to fly in the process)! The spreadsheet just gives a little structure to the insight process.

Paul

Ironflight said:

In an attempt to try and at least clarify the problem, I built a little spreadsheet that considers a flight to go and get 20 gallons of gas. It considers the price at each airport, the distance to the airport, and a set of variables such as fuel burn and ground speed that are held constant for each case.

Click to expand...

What, no correction for wind?


I have pretty cheap fuel available on my airport (now that they switched from AirBP to Phillips). I still stop at the neighboring airport to get gas as an excuse to go fly and "show off" the RV at the other airport. I am flying anyway.

Ironflight said:

After filling, the receipt said it was $3.65/gallon!

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Ouch! Oh, wait a minute. I just paid $4.85/gal for my fill up yesterday at my home airport (with 2 competing FBOs). And the fill up before that was $5.32, but that was because I was chasing $3.50 fuel that was no longer there and had to go to the really expensive place. Guess I can't muster up any sympathy after all.

I've thought about this problem as well. So what are the different scenarios?

1. I don't care where I fly within a certain radius, but I want to top off with some cheap fuel somewhere.
2. I'm flying to KXXX, and need to fill up on the way there (or way back) before the fuel level gets below X.
3. And the really hard one, I'm flying cross country to OSH and want to compare the cost of flying route X vs. route Y.

Don't look back

Wow, Paul, you have too much time on your hands that you are considering this and making a spread sheet. Most guys I fly with a couple of other criteria that weighs in.

According to your chart the most expensive trip cost for fuel is $14.35. For me and the guys I fly with the BS factor takes precedent. I'd have to be empty and fuel would have to have at least a dollar difference to fly else where fuel.

In most cases, the cost, the time and wear and tear on the engine are not worth a couple of bucks. Maybe for some, but definitely not for me. Your savings are minimal when all factors are considered.

Now, go back to building the 3.

Helps make the case for "aux" tanks in the plane

Saving fuel by topping off at the most logical airport is always on our minds, and like Paul, I'll do a spreadsheet for quick analysis at the drop of a hat.

There is *another* way to save fuel, however: and in the airline business, we call it "ferrying fuel". It works like this:

When at a cheap out station, we take advantage of the better price (or tax rate) by filling the plane with more fuel than we need for the trip. Then, when getting into the hub, the fuel-up for the next leg takes that much less. The cost of ferrying the fuel on the inbound leg is included, of course.

We could do this in our RV's too, if we had auxiliary fuel tanks - and some builders have incorporated aux tanks into their RV's. So, on the inbound leg if fuel is cheap at the out station, top off the mains + auxes and then you'll have less to buy at home, or maybe even could have full main tanks if the inbound leg wasn't too long.
I like this idea...

Davepar said:

3. And the really hard one, I'm flying cross country to OSH and want to compare the cost of flying route X vs. route Y.

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AirNav can do this one for you Dave - you go into their "fuel trip planner" (or whatever it is called), and it will give you various routes based on the criteria you select (range between stops is the sginificant one). It's pretty handy for a long trip!

BTW - I do find that when fuel prices are dynamic (changing quickly), Airnav can fall behind and give you bad data.

Your Formula is Not Complete!

Paul,
I am not an engineer, and did not stay at a Holiday Inn Express. But, you need to add .05/gal offset to your price if you get to use the "I need fuel" excuse for a chance to go fly. If the airport has a good restaurant, it goes up to .08/gal!! Disagree if you want, but just don't tell my bride!
Great spreadsheet, and I am sure that it will be very useful to all of us.
Thanks!

OK, I know most of you are from Texas and I'm from Europe where we view things a little differently and I am not a raving leftie....... Whatsmore, I am in the airline business and, yes, we tanker fuel to save money.

However I wonder whether, as a community, we should be promoting burning fuel to save a few dollars. You can argue that it is a drop in the ocean in relation to the world's consumption but there are plenty of people out there who view private aviation as an unnecessary, rich man's pursuit. If we are seen to be doing anything remotely un-green, eventually we will be regulated against. Perhaps not now in Texas, but eventually..........

paul330 said:

OK, I know most of you are from Texas and I'm from Europe where we view things a little differently and I am not a raving leftie....... Whatsmore, I am in the airline business and, yes, we tanker fuel to save money.

However I wonder whether, as a community, we should be promoting burning fuel to save a few dollars. You can argue that it is a drop in the ocean in relation to the world's consumption but there are plenty of people out there who view private aviation as an unnecessary, rich man's pursuit. If we are seen to be doing anything remotely un-green, eventually we will be regulated against. Perhaps not now in Texas, but eventually..........

Click to expand...

Well, there is always the theory that using it up quicker will force us to change our ways sooner...

A couple of fun tweaks to Pauls spreadsheet -

Here are a couple of fun tweaks I did that I think make the story even more interesting and useful,

First - to clarify the problem a little bit, I used this as the problem statement:

I'm here in my hangar, with 22 gallons in the tanks, and I would like to fill the tanks.

Note that this does not mean I am always buying 20 gallons. If I fly to another airport, I use some gas getting there before I fill up, so I am buying more than 20 gallons. Also, as in Paul's original spreadsheet, I don't have full tanks when I get home. But, I can figure out the equivalent cost per gallon of fuel that I bring home by how much I spend to fill up, and how much gas I have when I get back home.

Thats what I really want to know.

Note that the only "cost" here is the actual fuel purchase to fill the tank. The assumption is that we are always starting with the same fuel level, and the final fuel level factors into the effective cost/gallon.

Second, I modified the fuel burn model. In addition to the miles per gallon for the 'cruise' flight to the other airport, it is worthwhile to include the the fuel to take off and initial climb. This way, a trip to a very close-by airport gets penalized a bit, because you still burn fuel to take off, whereas a trip to a farther-away airport isn't affected much, because more fuel is used in the cruise portion of the flight.

Third, for those of us that do have fuel available at home, you can see how much you need to save in pump price to justify a flight ( filling at home doesn't get the take-off fuel penalty)

So, here is the revised spreadsheet:


You can see a couple of interesting things in the last column, the effective cost per gallon of fuel brought home. Take a look at lines 14 and 15. Flying 40 miles instead of 16 miles to save $0.39/gal at the pump is a mistake - its cheaper to pay more and fly shorter in this case.
Then, take a look at lines 17 and 18. Flying 23 miles instead of 6 miles to save $0.45/gal at the pump only nets $0.03/gal in effective savings.
Finally, if you can fuel at home, it is a break-even with a 20-mile trip even if it is $0.44/gal more at the home pump.

Another important thing - these trends really change if you need to buy more gas. If you start with 7 gallons in the tank, you only have to save $0.24 at the pump to justify a 20-mile flight. (But don't fly past your reserve fuel req'ment )

Now THAT's the spirit of collaborative engineering I was looking for! Great additions Steve - you need to email me the revised sheet! (work email is fine.....)

This is closer to the problem I was trying to solve. I like the concept of "effective cost per gallon".

This proves the old adage that the most difficult thing about answering a complex problem is accurately defining the problem - once you do that, the answer becomes almost self-evident.

Paul

Paul, when you finish the THREE, use it to make your fuel runs. It will be a lot of fun and you will have about 20 gallons to transfer.

Ironflight said:

BTW - I do find that when fuel prices are dynamic (changing quickly), Airnav can fall behind and give you bad data.

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Airnav is charging FBOs to be listed on the route planner, searches, and even when you type in a specific airport. Our airport's FBO switched from AirBP to Phillips recently. AirBP used to pick up the tab to be listed. Phillips does not. Our FBO no longer shows up on Airnav as management decided not to pay the fee. I wonder how many other small airport operators refused to pay the Airnav fee and therefore go unlisted. There may be more cheep fuel out there and my quest is to check out as many of those little airports as possible.

Are you still listed on 100ll.com? I use that site rather than airnav.com. I always wonder how good the "capture" is on these sites. Do they get everyone? Obviously airnav.com does not.

paul330 said:

OK, I know most of you are from Texas and I'm from Europe where we view things a little differently and I am not a raving leftie....... Whatsmore, I am in the airline business and, yes, we tanker fuel to save money.

However I wonder whether, as a community, we should be promoting burning fuel to save a few dollars. You can argue that it is a drop in the ocean in relation to the world's consumption but there are plenty of people out there who view private aviation as an unnecessary, rich man's pursuit. If we are seen to be doing anything remotely un-green, eventually we will be regulated against. Perhaps not now in Texas, but eventually..........

Click to expand...

And you're building an RV10, with SIX cylinders. Please....

I think I'm on board with Larry & the fuel trailer. Good idea there.

grantcarruthers said:

Are you still listed on 100ll.com? I use that site rather than airnav.com. I always wonder how good the "capture" is on these sites. Do they get everyone? Obviously airnav.com does not.

Click to expand...

Yes. My home airport is still listed on 100ll.com even after being dropped by Airnav. Do not think 100ll.com requires you to pay to be listed as I do not hink our airport would pay anybody to list its fuel price.

The one missing piece was the cost to fly your plane.

I plugged it at $30 and said it will take 15 minutes on both ends to taxi out, do the runup and then taxi to the pumps on the other end.

The flight costs were simply calculated using the distance to fly divided by the speed of the aircraft converted to MPH and then multiplied by the hourly operating cost.

N941WR said:

The one missing piece was the cost to fly your plane.

I plugged it at $30 and said it will take 15 minutes on both ends to taxi out, do the runup and then taxi to the pumps on the other end.[/img]

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Goodness, Bill. If anyone took 15 minutes to taxi (and runup) at the end of our airpark runway I suspect there would be some disgruntled neighbors! I doubt that we ever exceed five minutes. And, at the other end of the little airports with the best fuel, I think five minutes are typically plenty (unless things are hopping). It will obviously vary with hanger location, other traffic, need for an IFR clearance, and efficiency of the tower, but I suspect 5-10 minutes is more appropriate for most of us and these calculations.