Indicating fuel flow

[mhorowit]

First, I believe I recall seeing the fuel line from my wing tank being visible; in other words I could insert something in that line and see whatever it was I inserted.
Now - I'd like to see a positive indication I'm getting flow from my wing tank.
Do you remember in old auto service station fuel pumps there were a series of balls that would move around in a glass hemishpere when fuel was pumped?
Has anyone ever seen something smaller and similar i.e. floating plastic beads, that would bounce around in a small containor when fuel was flowing? Maybe I could insert that in the fuel line???- Mike.

[dehavalandb]

The best and most accurate way I think, is to watch the nose tank fuel gauge. When I drain the left tank it moves slowly but noticible after a couple of minutes. On the right tank it moves quickly enough to tell if the tank is draining right away. Your eyeballs will never be wrong.

[mhorowit]

Yes; but that's an indirect measure, complicated by the possibility that the wire gets catty-wampass and binds. Something like beads getting stirred up in the gas flow would be a positive indication of flow. - Mike

[crispy critter]

Beads

Mike,
The beads would just flow right down the line with the fuel and plug up the fuel line.If your wire fuel gauge seems to stick a little bit during mid-air refueling from the aux tanks(like most do)here's a little trick you can try to make the wire move,try moving the yoke up and down(forward and back)several times in a quick bouncing montion,this will rock the fuel in your main tank and will free up the wire gauge.
If you have never used the aux tank on your t-craft before or it has been a while since you have and your in dought of your aux tank working then try it out.Make sure your main tank is less than half full,fill up the aux tank,set the tail on a sawhorse or what ever you can find to put the tail up close to the same atitude as you would have in level flight and turn on the aux tank.Time it if you want to see how long it takes to drian out.It will usually take in a few minutes for the aux to empty into the main because it is gravity fed through a 3/8 or 1/4 inch fuel line.If you do not raise the tail then sometimes your aux tank won't completly drain empty,it usually will only drain about 1/2 to 3/4 out of the aux tank with the tail on the ground and it will drian much slower so you really need to raise the tail to get an accurate test drain.
Hope this helps

[Carl Ellis]

You may need some ram air coming in through your vented aux tank caps to get satisfactory flow. Some people have reported problems draining their tanks if this doesn't happen.

- Carl -

[jrzangger]

After restoring my plane I consistantly had difficulty in getting the wing fuel to drain to the main tank. I finally started using a procedure during fueling to guarantee fuel flow by leaving the fuel valve on - putting in four or five gallons - pressurizing the tank with my mouth (spit out your gum first). You can hear the air bubbles go through the line and then fuel will flow. Then, shut the valve off and top off the tank. If I didn't do that, I would not be able to get the fuel to transfer.

Now, a wiser Forest Barber told me to check the gasket on the fuel caps and make sure they were sealing properly. I replaced them with some nice white rubber ones, instead of the cork I had. Since then I have NEVER had any difficulty in transferring fuel from the wings. Apparantly, with the bad gaskets, the incoming air from the vent was just blowing back out the cap and not forcing the fuel through the line.

Hope this helps.

[ROllerton]

could it be that there is a low pressure area where the cap is, and if the seal leaks then fuel is held in the tank against gravity? And what ever pressure from the vent tube in the cap is lost to the lead to low pressure?

I had a similar problem in my former Decalhalon where the fuel gushed out under the caps while in flight.

[alwaysoar]

Does anyone know a source for wing tank caps, or how to make them? I recall a posting a while back. Someone said something about outboard motor tank gas caps.

Ed @ BTV VT
TF 527

[Carl Ellis]

Check with Harry at the factory - he says he has nose tank caps - both styles. Maybe he has wing caps as well.

[Robert Lees]

Now Mr Ollerton has hit the nail on the head. There is indeed low pressure just where the wing tank fuel cap is.

During the Taylorcraft design process, our friend Mr Taylor, being a methodical designer of English descent, must surely have thought: "Now if I put the wing fuel filler cap on the top of the wing just behind the front spar, where the air pressure due to wing lift is lowest, all the fuel will be sucked out".

Perhaps he thought "OK, then, I will put the fuel filler cap on the BOTTOM of the wing just behind the front spar, where the pressure is greatest" ( not as crazy as it may seem...you seen these modern airliners?).

But being the methodical and above all a designer of English descent, he realised that pressurised refuelling was just a few years away, so he must have thought:

"How could I INCREASE the pressure locally above the wing for the purpose of pressurising the tanks for fuel transfer?". Answer: put a small tube pointed forward into the airflow on the wing tank cap, with a reasonably tight cap seal to ensure the pressure remains inside the wing tank.

The rocket scientist said: "It's not brain surgery".

And the Brain Surgeon replied: " Ah, but my Luscombe has a cap looking like this, which encourages low pressure across the vent"

And the rocket scientist said something unprintable.

So why do some fuel cap vents point forward, and some point down? Answers in a plain envelope, please, with $100 dollars cash enclosed, to the undersigned.

Rob
p.s. they NEVER point aft.

[Forrest Barber]

Actually the Taylorcraft really has a "J" tube also someone has bent yours upward. I will send a photo of original one when I get back to the office. Later on Taylorcraft used a ram tube with a shroud like an augmentor. the J tube keeps rain out; the shrouded one does also in a bit of different fashion. Remember the placard " refill nose tank in LEVEL flight only boundary layer is very close to the top surface.....never saw fuel sucked out of a 6 gal tank with proper cap......pointed forward with good gasket.