Minimum Takeoff Fuel?

[VictorBravo]

Can anyone remember if there is a minimum amount of fuel needed in the tank for takeoff on a B model?

Has anyone had an experience where they were taxiing out for takeoff with minimal fuel on board, and maybe taxiing uphill a little, and the engine stopped running (presumably from the fuel you had on board being too far aft in the tank)?

Yesterday I went to takeoff from an airport only about 10 minutes flying time from my home base. I knew I had minimal fuel on board, but I think I had at least 30 minutes of fuel (in level flight). The reason I believe this is because the fuel gauge wire was about an inch above the fuel cap when I arrived in level flight at that nearby airport. To my surprise, as I was taxiing uphill toward the runway, it apparently ran out of gas on the taxiway.

Nothing was awry in the engine room. I put another few gallons in it, it started up fine, I was able to takeoff and climb at very best angle (for safety), and it ran like a sewing machine all the way home.

I've never seen a placard in a T-craft saying "no takeoff with less than 1/4 tank" like some other airplanes, but then I've had four Taylorcrafts and never had a flight manual either.

Is there some known issue with taking off with less than X gallons?

[AKbrew]

Re: Minimum Takeoff Fuel?

My F-19 is placarded for "9 gallons usable" in the 12 gallon header tank, apparently due to fuel flow issues at an incline. My BC-12D did not have that restriction, however.

[Forrest Barber]

Re: Minimum Takeoff Fuel?

Early B's had no "flight manual" they use placards. Our B's run till the last drop is used up in level flight. Look at the bottom of the tank, if you do not exceed a nose up atitude that would cause the bottom of the tank to go past level you should be fine. there is no unusable fuel on the B's.
Yes the F-19 had the 3 gal becuase of the extreme climb angle , I flew the test, just lower the nose a bit and you can use it all like the lower HP ships.

[VictorBravo]

Re: Minimum Takeoff Fuel?

So then what caused my engine to stop ?!?!?!?!?

[paulnuss]

Re: Minimum Takeoff Fuel?

How steep was the hill you were taxiing up? IF substantially steeper than the angle of the bottom of the tank from level, and/or IF acceleration might have sloshed all the gas to the back?

[Pearson]

Re: Minimum Takeoff Fuel?

Bill,

It makes me suspect the accuracy of your fuel gauge.

[Dano"T"]

Re: Minimum Takeoff Fuel?

Hey...I was flying my 90HP BC12D on Floats Saturday....gave many rides...then I took off to go home which was the next lake over over (1 mile maybe) I had the same thing....about an inch on the fuel gauge....i got it on the step...pulled it off the water and as soon as I started to leave ground effect...she quit! I pushed the nose down and it started again....I landed, checked for water (found a small drop in the bowl so I drained it one more time) I took off again...Same Thing! It quit until I pushed the nose level....I first thought Water, then i thought vapor lock....but I bet it is the steep climb and minimal fuel...The C90 is probably comparable to the O-200 in fuel flow...so that could be it....it ran just fine when I leveled it out.

[Jim Hartley]

Re: Minimum Takeoff Fuel?

I have a BC-12D, C-85. When I climb steep in a short field take-off with less than appromately 2 -2.5 gallons of fuel, the fuel line will unport and the engine will starve for fuel. Much of my flying is off relatively short lakes and a short field take-off is required...55-60 mph indicated...My personal minimum is five gallons of fuel on board.

Jim

[Robert Lees]

Re: Minimum Takeoff Fuel?

Unporting of the fuel outlet is the issue here. As already described, the higher-horsepower Tcraft have a steeper climb angle, so unporting of the header tank occurs more easily.

There was a "King Kong Cub" built in the US a few years ago, with such an enormous engine, the climb angle was so steep that the carburettor would become higher than the wing tanks (yes, wing tanks!), and the engine would splutter. Not the same as unporting, of course, but the same effect.

[Ray36048]

Re: Minimum Takeoff Fuel?

Maybe someone could post some pictures or diagrams of the correct plumbing from the tank. My project airplane tank has 2 outlets from the tank. The one in the front on the bottom and one on the rear of the tank on the vertical surface near the bottom.

It looks to me like if there was a tube that ran between these 2 outlets, fuel could feed from the back in a very nose up attitude. The outlet would be lower than the one in the front but still higher than the carb. No real measurements here just an obsevation.

This would not be much different than the main fuel tanks in a Citabria I fly. 2 outlets from the wing tanks. One in the front and one in the back. One for nose up and one for nose down.

[VictorBravo]

Re: Minimum Takeoff Fuel?

Hey guys... I was on the ground when it quit.

My plane's on 6.00 x 6 standard tires, with a standard Maule solid tailwheel. I was taxiing at 10 miles an hour, uphill maybe 5 degrees at the most.

Does anyone think THAT's nose-high enough to cause the outlet to unport? I can understand it unporting on a 55 mph best rate climb, but I wasn't climbing or even accelerating that much... I was rolling along down a taxiway.

[vetdrem]

Re: Minimum Takeoff Fuel?

I had the same thing happen to me. I found that the neoprene needle valve wasn't letting fuel to flow to the bowl when the fuel level was low, and I had even a slight up angle. The head pressure of the fuel in the tank wasn't enough to make the fuel flow. I replaced the needle and seat with a steel one and haven't had a problem since.

I suggest that you check the needle valve.

[Len Petterson]

Re: Minimum Takeoff Fuel?

My minimun take off fuel is 45 minut reserv + flight time. In practics 2 gallon min for a short flight 1 or 2 circuts.
At my new homestrip I am parked on the uphill and I can NOT use the float or the fuel measuring stick in a reliable way as the fuel does not sit in the tank at the same angel, how mush difference it makes I have yet to find out.
I know the tail is always damp no good for corrosion.
My next project is to make a ramp for the tail.
Len

[dennispip]

Re: Minimum Takeoff Fuel?

Whatever the reason, ROF (running out of fuel) is the leading cause of non-planned off airport touchdowns. In slow landing A/C your chances are better of not hurting yourself, a passenger, the A/C, or something on the ground, but why ever take the chance??? It also attracts the attention of the FAA, not something anyone needs.

If your minimums are 30 minutes of fuel, you need to be absolutely sure you have that amount available and that it will get to the engine. Gages of any kind must be verified by a dipstick or visual confirmation before taking off, especially in minimal fuel situations and if any doubt, add a couple of gallons or wait until you can.

If the engine is quitting before actual exhaustion of the fuel, something is wrong and it should be fixed before the next flight.

Don't let this ruin a good day. Not ever worth taking a chance on this happening and it happens way too often.

[Joel Severinghaus]

Re: Minimum Takeoff Fuel?

I second Dennis on the value of a dipstick. It's a tedious process, but please make yourself one. Get a wooden dowel from the hardware store or hobby shop, and a gallon container. Pour one gallon of fuel into your empty tank, put in the dipstick, and mark the wet level on the stick. Repeat one gallon at a time until the tank is full and you have twelve marks up your stick.

Hint I learned the hard way: leave the dipstick long enough that it can't fall completely into the tank from any angle.

Besides knowing relatively precisely how much fuel is left in your tank, you can also know how much you need to add when refueling, so you or the lineboy don't over-fill it and run fuel all over your cowling and into your cockpit. (Another thing I've learned the hard way.)