Gents,

we often read about problems with the fuel tank of model air planes. Too high positioned!!?
I do make a post in my own thread so I can use it in the future again and gain!!

Some history of the tank lay-out,
page 2 of Classic Pattern Flying.

http://www.rcuniverse.com/forum/m_3146645/tm.htm

The last message about this subject of Tomlee, post 80
http://www.rcuniverse.com/forum/m_52...mpage_4/tm.htm post 80”

But also Rendegade, post 8, some time ago.
http://www.rcuniverse.com/forum/m_65.../tm.htm#654111 post 8

And there will be much more!!!

We can read always a lot of advices and never see any drawing.
Sometimes there are even people who let us build nearly a new plane or talking about complicated solutions!

WRONG

When you THINK the tank is too high positioned in your plane try what Evangelista did show us.
Evangelista Torricelli did show us in the very past there can be a vacuum above the liquid surface generated, see also page 15 of this thread.
The vacuum above the fuel is generated after some drops of fuel do flow out the tank to the engine (or after reverse the fuel supply pump a moment!).
What to do? Simple make the air inlet in the tank on the same level as the spray bar (in horizontal flight position, cruise speed)

I already did show the design of the first contest Taurus of Ed was made for this most optimum tank lay-out, see sketch picture 2,
See, when the tank is full, also in that situation there can be a fuel flow to the engine?

I show again this lay-out (see page 15) , now with added a fill facility, “remove before fill” in the dotted line, so three tank connections if you want. After filling the tank, it is important to close the second air inlet tube again!
Without this facility you can fill the tank only in vertical nose up position of the plane! (never get an answer for that question in the past!)

BTW
I do not know the name “Uni-flow” (See Tomlee) as I read in the last “problem post” answer , but maybe that is the modern name for this old and forgotten lay-out.

This tank lay out eliminates a lot of the difference between normal and inverted flight with a full tank and for that reason was used in the past for pattern (and C/L!) to combine with the bleed air carb.

When the engine “run” there can be one airflow throught the air inlet connection so you do not spil fuel during “inverted” flight.

In normal flight there can be a more ‘constant’ fuel / air ratio as result of underpressure in a “full” fuel tank

Don’t you want any drop of fuel on the floor in the pits, even when the environmental temperature rizes? A clip over the fuel line between tank and carb is the proven solution, see some old pictures.

After you do try this method and it does not work, you mights change anything in your plane, but first I did want to show you this “OLD” solution, I also use myself.
Oh and BTW look to this antique drink bottle for our little birds! (picture 3), Ed Kazmriski wasn't the only one who already did know it all in the past!

More to come


Cees