fuel tank plumbing

[pwm]

My apologies to the group if this has been covered recently.

I bought a Smith Miniplane DSA-1 off eBay recently which has a 10gal aux
fuel tank in the upper wing center section which is not plumbed into the
fuel system yet. I would like some input from the RAH gallery as to how this
could be accomplished; all practical ideas would be most welcome, with
emphasis on simplicity. The fuel system in operation to feed the O-200
presently is a 12gal fuselage tank directly behind the firewall with about a
2gal header tank underneath.

Thanks,
Monty

[Ed Sullivan]

On Tue, 25 Jan 2005 08:46:25 -0600, "pwm" > wrote:

>My apologies to the group if this has been covered recently.
>
>I bought a Smith Miniplane DSA-1 off eBay recently which has a 10gal aux
>fuel tank in the upper wing center section which is not plumbed into the
>fuel system yet. I would like some input from the RAH gallery as to how this
>could be accomplished; all practical ideas would be most welcome, with
>emphasis on simplicity. The fuel system in operation to feed the O-200
>presently is a 12gal fuselage tank directly behind the firewall with about a
>2gal header tank underneath.
>
>Thanks,
>Monty
>
>
I'm not sure why you have a header tank unless it is for inverted
flight. On my Jungster the wing tank feeds into the fuel valve as does
the fuselage tank. I can then select either the wing or fuselage tank,
but not both otherwise the wing tank could overflow the fuselage tank.
I have both upright and inverted vents on the fuselage tank and
inverted tank. On the wing tank I just use a vented cap.

Ed Sullivan

[Corky Scott]

On Tue, 25 Jan 2005 08:13:09 -0800, Ed Sullivan >
wrote:

>I'm not sure why you have a header tank unless it is for inverted
>flight. On my Jungster the wing tank feeds into the fuel valve as does
>the fuselage tank. I can then select either the wing or fuselage tank,
>but not both otherwise the wing tank could overflow the fuselage tank.
>I have both upright and inverted vents on the fuselage tank and
>inverted tank. On the wing tank I just use a vented cap.
>
>Ed Sullivan

Really? You can't just plumb the wing tanks into the header tank?
Thought that was done all the time. Is it necessary to vent the
header tank if the wing tanks are properly vented?

Thanks, Corky Scott

[jls]

"Corky Scott" > wrote in message
...
> On Tue, 25 Jan 2005 08:13:09 -0800, Ed Sullivan >
> wrote:
>
> >I'm not sure why you have a header tank unless it is for inverted
> >flight. On my Jungster the wing tank feeds into the fuel valve as does
> >the fuselage tank. I can then select either the wing or fuselage tank,
> >but not both otherwise the wing tank could overflow the fuselage tank.
> >I have both upright and inverted vents on the fuselage tank and
> >inverted tank. On the wing tank I just use a vented cap.
> >
> >Ed Sullivan
>
> Really? You can't just plumb the wing tanks into the header tank?
> Thought that was done all the time. Is it necessary to vent the
> header tank if the wing tanks are properly vented?
>
> Thanks, Corky Scott

Well, maybe, but wing tanks on a Taylorcraft are vented with ram-air tubes
on the caps and so is the header tank. In flight those tubes make positive
pressure on the 6-gallon wing tanks and the 12-gallon header tank.

I've seen a few times, too, that the wing tank gets balky emptying into the
header tank during flight, despite the ram-air tubes.

[Corky Scott]

On Tue, 25 Jan 2005 13:14:41 -0500, " jls" >
wrote:

>Well, maybe, but wing tanks on a Taylorcraft are vented with ram-air tubes
>on the caps and so is the header tank. In flight those tubes make positive
>pressure on the 6-gallon wing tanks and the 12-gallon header tank.
>
>I've seen a few times, too, that the wing tank gets balky emptying into the
>header tank during flight, despite the ram-air tubes.

Well if the header tank is below the wing tanks, and the header tank
is vented, what's preventing the wing tanks from overfilling the
header tank as Ed Sullivan suggested?

Does the header tank vent have a checkvalve?

I was picturing the header tank being downstream of the wing tanks and
not being vented. In effect, the header tank is simply a distorted
downstream fuel line.

Thanks, Corky Scott

[jls]

"Corky Scott" > wrote in message
...
> On Tue, 25 Jan 2005 13:14:41 -0500, " jls" >
> wrote:
>
> >Well, maybe, but wing tanks on a Taylorcraft are vented with ram-air
tubes
> >on the caps and so is the header tank. In flight those tubes make
positive
> >pressure on the 6-gallon wing tanks and the 12-gallon header tank.
> >
> >I've seen a few times, too, that the wing tank gets balky emptying into
the
> >header tank during flight, despite the ram-air tubes.
>
> Well if the header tank is below the wing tanks, and the header tank
> is vented, what's preventing the wing tanks from overfilling the
> header tank as Ed Sullivan suggested?

I never saw Ed's post, but I can tell you from my own experience that if you
haven't run at least six gallons out of the header tank before you open the
valve on a wing tank, you're going to get overflowing gas sprayed from the
vent tube all over the windshield.
>
> Does the header tank vent have a checkvalve?

No. I've never heard of one. Taylorcrafts are made to fly, not to be
overly complicated.
>
> I was picturing the header tank being downstream of the wing tanks and
> not being vented. In effect, the header tank is simply a distorted
> downstream fuel line.

That very well may work, Corky, but I think I'd want the header tank vented.
>
> Thanks, Corky Scott
>

Thanks to you too.

This thread reminds me of the two guys flying a Taylorcraft cross-country
from East to West Tennessee. They stopped near Knoxville to refuel and had
the lineboy fill the wing tanks. As they flew along enjoying themselves,
counting cows in the green pastures below, the wire gauge dropped and they
decided to refill the header by dumping the contents of a wing tank. The
trusty copilot opened a valve and no gas. He opened another valve and no
gas. They began to look for a landing strip to put down, but the engine
quit they landed and nosed over in a muddy cow pasture. The lineboy had
screwed the lids on the wing tanks with the ram air tubes backwards. Low
pressure caused all the gas to be sucked out and emptied the tanks.

[Mark Smith]

Corky Scott wrote:
>
> On Tue, 25 Jan 2005 13:14:41 -0500, " jls" >
> wrote:
>
> >Well, maybe, but wing tanks on a Taylorcraft are vented with ram-air tubes
> >on the caps and so is the header tank. In flight those tubes make positive
> >pressure on the 6-gallon wing tanks and the 12-gallon header tank.
> >
> >I've seen a few times, too, that the wing tank gets balky emptying into the
> >header tank during flight, despite the ram-air tubes.
>
> Well if the header tank is below the wing tanks, and the header tank
> is vented, what's preventing the wing tanks from overfilling the
> header tank as Ed Sullivan suggested?
>
> Does the header tank vent have a checkvalve?
>
> I was picturing the header tank being downstream of the wing tanks and
> not being vented. In effect, the header tank is simply a distorted
> downstream fuel line.
>
> Thanks, Corky Scott


The header tank could have a vent the sme height as the wing tanks,

it would fill completely, bleed to the open air,

I would perhaps vent the header tank to the wing tank/s, not open air,
at any level
--


Mark Smith
Tri-State Kite Sales
1121 N Locust St
Mt Vernon, IN 47620
1-812-838-6351

http://www.trikite.com

[Ed Sullivan]

On Tue, 25 Jan 2005 12:16:41 -0500, Corky Scott
> wrote:

>On Tue, 25 Jan 2005 08:13:09 -0800, Ed Sullivan >
>wrote:
>
>>I'm not sure why you have a header tank unless it is for inverted
>>flight. On my Jungster the wing tank feeds into the fuel valve as does
>>the fuselage tank. I can then select either the wing or fuselage tank,
>>but not both otherwise the wing tank could overflow the fuselage tank.
>>I have both upright and inverted vents on the fuselage tank and
>>inverted tank. On the wing tank I just use a vented cap.
>>
>>Ed Sullivan
>
>Really? You can't just plumb the wing tanks into the header tank?
>Thought that was done all the time. Is it necessary to vent the
>header tank if the wing tanks are properly vented?
>
>Thanks, Corky Scott

Corky, I don't know why you need a header tank with a fuselage tank. I
have an inverted tank at the bottom of my fuselage tank which is
separate from the main tank, but has a 1" tube running to the bottom
of it to feed the inverted tank. Both it and the main tank are vented
for upright flight and a second vent runs from the inverted tank for
inverted flight. The fuel is fed to the fuel valve through an
aerobatic flop tube. When I am on the wing tank I switch the valve and
the fuel gavity feeds to the gascolator. I haven't looked at it in a
long time, but the location of the vents is pretty critical.

Ed Sullivan

[pwm]

So far, I am down to two concepts:

1) feed header tank from either main fuselage tank or upper wing tank with a
main/aux selector valve

2) feed header tank from only the main fuselage tank; fill main fuselage
tank (only until sight gauge shows full) from the upper wing tank via a
shutoff valve

Any other suggestions? (keep 'em simple)

Monty

[[email protected]]

Don't use a header tank with a separate vent, no matter what
the height of the vent. There have been homebuilt crashes resulting
from unbalanced venting of tanks, and certified aircraft having
interconnected tanks (a "both" position) MUST have a common vent
system. The Cessna 172, for example, has a single vent unde the left
wing that is plumbed into the left tank, and a line from the top of
that tank to the top of the right tank. This maintains equal pressure
in both tanks, and therefore equal head on the fuel.
I recall a homebuilt that suffered engine failure because the
guy had installed a header tank under the panel fed by the wing tanks.
The header had its own vent plumbed up to the wing root, and due to
aerodynamic considerations had a slightly higher pressure than the wing
tanks. (It can easily happen when the wing tank caps are vented;
remember that the zone above the wing has a rather low pressure.) The
wing tanks would not drain into the header and the engine quit at a
really bad time after takeoff. The header should have been vented into
the top of the wing tanks.
Another case: the Glastar had (might still have) two wing tanks
plumbed into a single on-off valve in the cockpit. The tank vents were
run from each tank out to the tip of each wing, where they stuck down
into the slipstream and were cut on a 45 degree angle facing forward.
Besides scratching the head of anyone passing under the tip, they
provided uneven pressure to the tanks and one tank would run dry before
the other. If the pressure differential was large enough, the full tank
would not feed at all. We fixed that by running another line between
the inboard ends of the tanks. There were fittings conveniently welded
into the tanks at the right spot for this. The other drawback of tip
vents: Parked on a bit of a sideslope, the full tanks will send fuel
out the low vent, and the fuel from the high tank runs through the
plumbing (even with the valve off) and into the low tank, and you come
to work to find 15 gallons of fuel on the floor waiting to ignite.
We disconnected the tip vents and put ram tubes on the filler
caps. Stuck them up high enough to get out of the lowest pressure.
Gee, I'm talkative tonight. But I wish there was a website or a
book published for homebuilders with all the "Don't Do This" stuff in
it to keep us from making the same mistakes our predecessors made. It's
dumb to die twice for the same error.

Dan

[Ed Sullivan]

On Tue, 25 Jan 2005 19:25:52 -0600, "pwm" > wrote:

>So far, I am down to two concepts:
>
>1) feed header tank from either main fuselage tank or upper wing tank with a
>main/aux selector valve
>
>2) feed header tank from only the main fuselage tank; fill main fuselage
>tank (only until sight gauge shows full) from the upper wing tank via a
>shutoff valve
>
>Any other suggestions? (keep 'em simple)
>
>Monty
>
>
The simplest is to plumb the wing tank through the aux side of the
fuel selector valve directly to the gascolator and use a vented cap.
You haven't really given enough detail about how your main and header
tanks are set up and connected. Will you have a fuel pump or is
everything gravity feed?

Ed

[puck]

> The simplest is to plumb the wing tank through the aux side of the
> fuel selector valve directly to the gascolator and use a vented cap.
> You haven't really given enough detail about how your main and header
> tanks are set up and connected. Will you have a fuel pump or is
> everything gravity feed?
>=20
> Ed
>

Everything gravity feed is the objective. The header tank sits on the =
cockpit floorboard, directly underneath the main fuselage tank. The =
12gal main tank is plumbed directly with fittings to the aft end of this =
cylindrical header and the gascolator is mounted on the foreward end of =
it on the engine side of the firewall. The main tank has a vented filler =
cap, as does the upper wing tank. Presently, I can find no shutoff =
valves installed, but plan to install one when I figure this out.

Thanks,
Monty

[Hatz Lyman C]

Putting the wing fuel caps on backward on a Taylorcraft will not suck the fuel
out of them. It will just not let them flow into the main tank. All you have
to do is land and turn the caps around and you are good to go.

Lyman

[jls]

" jls" > wrote in message
...
>
> "Corky Scott" > wrote in message
> ...
> > On Tue, 25 Jan 2005 08:13:09 -0800, Ed Sullivan >
> > wrote:
> >
> > >I'm not sure why you have a header tank unless it is for inverted
> > >flight. On my Jungster the wing tank feeds into the fuel valve as does
> > >the fuselage tank. I can then select either the wing or fuselage tank,
> > >but not both otherwise the wing tank could overflow the fuselage tank.
> > >I have both upright and inverted vents on the fuselage tank and
> > >inverted tank. On the wing tank I just use a vented cap.
> > >
> > >Ed Sullivan
> >
> > Really? You can't just plumb the wing tanks into the header tank?
> > Thought that was done all the time. Is it necessary to vent the
> > header tank if the wing tanks are properly vented?
> >
> > Thanks, Corky Scott
>
> Well, maybe, but wing tanks on a Taylorcraft are vented with ram-air tubes
> on the caps and so is the header tank. In flight those tubes make
positive
> pressure on the 6-gallon wing tanks and the 12-gallon header tank.
>
> I've seen a few times, too, that the wing tank gets balky emptying into
the
> header tank during flight, despite the ram-air tubes.
>

Let me elaborate on this rather uncomplicated fuel vent system on the
Taylorcraft. The 12-gallon header tank is fixed to 4130 fuselage tubes and
sits behind the firewall and in front of the panel. Its vent --which is
merely an acute angle cut facing forward in a vertical tube rising from the
filler cap on the boot cowl just forward of the windscreen -- is also the
hole through which the fuel gauge wire moves up and down according to the
quantity of fuel in the header tank.

Obviously the positive pressure supplied by this vent tube is slightly less
than the pressure provided by either of the ram-air tubes on the wing tank
caps. Otherwise, wing tank flow into the header tank might not occur. And
I've seen that happen with Taylorcrafts other than mine.

Some people install glorified ram air tubes on their wing tank caps. They
braze onto the caps longer tubes pointed into the slipstream and bellmouth
them. The apparent fix gives them a better pressure differential to push
wing tank fuel down into the already pressurized fuselage tank. Of course,
with the valves on the wing tanks closed, the fuselage tank must have some
way of its own to maintain positive pressure to feed gasoline through the
gascolator and into the carburetor bowl, especially in a climb where
sometimes gravity alone is not enough.

C. G. Taylor, also the designer of the Cub, must have been thinking about
those steep climbs in a Taylorcraft when he designed the ram-air tubes on
the wing tanks because they are bent more than 90 degrees downward so they
face directly into the slipstream during a steep climb.

On the subject of a small header tank in addition to a fuselage tank, that
sure does sound a little like Rube Goldberg to me. It must a device to cure
a history of fuel starvation, something I have never heard of in a simple
system like the Taylorcraft's. OTOH,maybe there's a good reason for it.

I have flown a Taylorcraft since the eighties and never had it give trouble
feeding from the wing tank to the fuselage tank, with one or two exceptions.
And never ever had a fuel starvation problem. Here are the exceptions:
You know those socks you put over a 172's pitot tube to keep bugs out while
you're sitting on the ramp? Well, those bugs, angry at the socks on 172's,
will seek out and set up housekeeping in your ram-air tubes. So you just
take a length of .016 safety wire and punch the little *******s out. When
you get one in your 172's pitot because like me you were too slack to put on
the sock, the cure is not so easy.

[jls]

"Hatz Lyman C" > wrote in message
...
> Putting the wing fuel caps on backward on a Taylorcraft will not suck the
fuel
> out of them. It will just not let them flow into the main tank. All you
have
> to do is land and turn the caps around and you are good to go.
>
> Lyman

I think you're probably right, but I've never had the experience, having
learned long ago to pre-flight. This practice was reinforced after a
line-boy gassed us up and put those lids on backwards in Kankakee.

[Corky Scott]

On Wed, 26 Jan 2005 09:38:14 -0500, " jls" >
wrote:

>C. G. Taylor, also the designer of the Cub, must have been thinking about
>those steep climbs in a Taylorcraft when he designed the ram-air tubes on
>the wing tanks because they are bent more than 90 degrees downward so they
>face directly into the slipstream during a steep climb.

There is another possible reason for angling the ram tubes slightly
downward: it prevents rain drops from entering the vent system while
in flight, and sitting on the ground.

Corky Scott

[Corky Scott]

On Tue, 25 Jan 2005 16:25:13 -0800, Ed Sullivan >
wrote:

>Corky, I don't know why you need a header tank with a fuselage tank.

Sorry, this was a part of the post I missed. I did not realise that
was the situation.

I was thinking purely about wing mounted tanks plumbed into a header
tank.

Corky Scott

[[email protected]]

>C. G. Taylor, also the designer of the Cub, must >have been thinking
about
>those steep climbs in a Taylorcraft when he >designed the ram-air
tubes on
>the wing tanks because they are bent more than 90 >degrees downward so
they
>face directly into the slipstream during a steep climb.

The down angle is to keep rain out. The airflow will be parallel
to the top of the wing in any attitude except full stall.

>On the subject of a small header tank in addition to >a fuselage tank,
that
>sure does sound a little like Rube Goldberg to me. It >must a device
to cure
>a history of fuel starvation, something I have never >heard of in a
simple
>system like the Taylorcraft's. OTOH,maybe there's a >good reason for
it.

Some airplanes had tiny header tanks to increase usable fuel.
In a slip or steep nose-down glide (especially with flaps on some
aircraft) the fuel moves away from the tank outlet and the engine might
starve if the tanks are low. The small header is intended to keep the
engine supplied while in that attitude. The Glastar had a retrofit kit
of two small headers to overcome the starvation problem, since the very
effective flaps resluted in a rather large unusable fuel quantity,
limiting range.
Other airplanes use two tank outlets, one front and another
rear, plumbed together. Citabria is a good example.

Dan

[guynoir]

On the Champ, wing tanks drain directly into fuselage tank. There's a
valve for each wing tank. If you open that valve before the fuselage
tank has drained sufficiently, gas will spray out the filler cap vent
onto the windshield.

Corky Scott wrote:
> On Tue, 25 Jan 2005 13:14:41 -0500, " jls" >
> wrote:
>
>
>>Well, maybe, but wing tanks on a Taylorcraft are vented with ram-air tubes
>>on the caps and so is the header tank. In flight those tubes make positive
>>pressure on the 6-gallon wing tanks and the 12-gallon header tank.
>>
>>I've seen a few times, too, that the wing tank gets balky emptying into the
>>header tank during flight, despite the ram-air tubes.
>
>
> Well if the header tank is below the wing tanks, and the header tank
> is vented, what's preventing the wing tanks from overfilling the
> header tank as Ed Sullivan suggested?
>
> Does the header tank vent have a checkvalve?
>
> I was picturing the header tank being downstream of the wing tanks and
> not being vented. In effect, the header tank is simply a distorted
> downstream fuel line.
>
> Thanks, Corky Scott
>

--
John Kimmel


Naturally, these humorous remarks are all entirely my own opinion, based
solely
on rumor, supposition, innuendo and damned lies, and should be
interpreted in a
spirit of fun. My memory is faulty, also.