There are common in aerobatic plane, 3D etc.. but if your engine are flooded by fuel (siphoning fuel into engine), move the tank a bit lower.

IMO the diagram puts the tank at just the right position.

On a typical upright engine installation, it's a bit of a challenge getting the tank high enough. If it was me, I would just let the tank peek out the top of the fuselage. Not pretty, but functional.

The alternative: mount the engine horizontal and the carburator will be lowered, then the tank installation will be placed in right height to main needle.

But most generally: Follow the building construction/plan of aircraft where the engine and tank will be placed in right place.
Some time the tank are in the kit of model airplane, and follow instruction where the tank are placed.

Quote:

ORIGINAL: Motorboy

But most generally: Follow the building construction/plan of aircraft where the engine and tank will be placed in right place.
Some time the tank are in the kit of model airplane, and follow instruction where the tank are placed.

Jens,


This is the exact problem!
Most kits and nearly all ARFs, that have the engine mounted upright (or inverted), DO NOT place the fuel-tank at the proper level.

This is a fact.

If the engine is upright, the fuel-tank will most likely be lower than ideal!

If such a model is built according to plans, or in an ARF, according to the instructions; when the plane is flown inverted, the engine will be running significanly richer than it ran when the plane was right-side-up... This is because the instructions/plans tell the builder/assembler to mount the engine too high!

With the holes already drilled in the firewall, there is not much of a choice.

And as to the large hole in the firewall, for the fuel-tubing (in which most normal tanks' 'snout' fits); it is always located behind the crankshaft center-line; not behind the carburettor...
This means it is about 40 mm (1.5" ) too low...

I do not had problems with the motor by tank positions recommended by instructions and plans.
Have not experienced the problem with the Kyosho modelairplane (Messerscmitt BF-190 and PT-17 biplane).

It's not every day we read about problems tank placement in the forum. How many have ARF model airplanes in total, and rare to complaint about the tank location. It depends on the tank and engine placement is critical to the flight characteristics and engine setting for some model airplane and engines who are sensitive by fuel mixture in relating to the tank location.
The second problem may come if a switch from 2 stroke engines to 4 stroke engine or vice versa and get problem without repositioning the tank to right height again because the height of carburetor is quite difference in the 2 - and 4 stroke engines.
The last problem are length between engine and tank who make more lean (climbing) or rich (sinking) fuelmix.

Hi!
Tank position is a big problem if you mount the engine up-right!
A much better position is to mount it sideways.

If you're committed to an upright installation, because the holes have already been drilled, etc. Another alternative, is to simply heighten the fuselage above the tank somewhat. Once again, not necessarily attractive, but it solves the problem:

I kinda like the sideways mount too. Even more now that I have seen how important tank position can be. Would have been nice for WM to have pointed this out in the instructions befor I cut me cowling like the book said. But I guess if you learn something from it the mistake was worth it. Just a note for models makers. look at the Aeroworks Edge 540. They not only went with sideways, they put a diagonal slant to fit the cowl without alot of bucthering. They even offered options for other mounts with engine and tank aligned in all of them. I call that quality in a kit, even an ARF.

I have found side mounting an engine makes getting the tank / engine setup very quick and easy. The result makes for a dependable and powerful setup as it will hold a setting for the entire tank. I know you have seen alot of ideas. I hope you can find a system that works well for you. I know I tried several before I was truely happy. Good luck in your search......

turbo