Hello Ben,
ORIGINAL: Ben Lanterman
Cees the first drawing of the RC tank should have the venting air line inside of the tank attached to a piece of bent metal tubing. This positions the end of the vent tubing right next to the top of the tank and prevents the siphoning of the fuel when the tank is full. Ed's tank with the red band seems to be a two tubing tank - one to the motor and one for venting. As you can see the venting line does have the bend to the top of the inside of the tank. It looks as if the metal tubing outside of the tank broke off. The flow to the motor, as your drawing shows, is dependent on fuel position relative to the needle valve.
If the tank is level it doesn't matter where the vent is - the vent just bubbles until you have a constant pressure inside the tank. If you are maneuvering the internal pressure varies a lot but apparently the motors can handle it fine - most modelers just flop the vent over the side or leave it stuck up in the air.. You can put the vent forward but the pressure varies a bit too much.
Making the venturi smaller certainly eliminates some of the sensitivity of this operation. Certainly Ed seemed to go for the least complicated solution for problems. He probably fueled through the line to the motor if it is a two line tank.
I had a bad inner ear problem so never got into control line but I remember reading about a "chicken hopper" fuel tank design one time.
Ben
I only did say, It could be the way Ed did use the tank to get a constant ratio of air / fuel, independent of level and when the amount of fuel is more than 50 %.
It will not work perfect but maybe better than much systems when we really know the details of Ed.
I want to warn Kingaltair because when you do not know these details you are throwing away HIGH IMPORTANT INFO, without knowing!!!
This is Daniel Bernoulli! (dutchman) but also Blaise Pascal, I am an instrumentation and controll engineer.
If you mount a tube to the top it does not work the way I mean, (you can shake it LOL)
After siphoning a few drops you have the right under(sucking?) pressure of h x specific mass, equal to the heigth of fuel in the tank, so compensation. So the Hydrostatic pressure on the carblevel in the tank is the same as the baromatric pressure of the air around the carb!!
I measure the pressure of the air at the inlet of the carburator because I use a diffuser for cooling so the overpressure in the engineroom I have to count with.
BTW, I did know you would not know this and not believe me, so that's the reason I already did make the picture for Kingaltair.
My warning was, to now how to fill the tank!!!!!!!!!
Of course I am not sure, it was not my intension to win, but help, see the start of my post.
Only you must know Bernoulli and or Blaise Pascal to know these details. I think Ed did know this also so I count with every trick he could have used to win.
The ratio is primary, there are lots of other provits when it works, less consumption less change of CG etc (even less metal, it's a wonder)
This is the reason I do use two pressure controllers, one for the fuel, one for the tank.
No more and no less, or you do want believe it or not.
Cees