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I am well aware of the fuel tank position argument in relation to engine inlet position, i.e. below the engine inlet. Trouble is I have a Tucano complete with retracts and the tank outlet sits above the inverted engine inlet. Unless I remove the front retract, daft solution, I have little space to reposition the tank. I could perhaps set way back in the fuselage, is that a good idea, find or make a tank, subject to dimension and position, or maybe make a bladder tank.

The engine will run and is easily started with the model inverted, its the flooding issue when fueling and starting when its upright.

Please bare in mind the model was designed this way and I know that they are flown. 

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The carb spray bar should ideally be level with the tank centre line but I have found that somewhere within the tank is ok .I had a DB 1/4 pup with a laser 200 v twin .The tank was way above the carb but the engine ran fine if I didn’t fly inverted 

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Two options, put the tank in the right position or put the engine in the right position.


Failure to adhere to either option 1 or 2 will result in sub optimal running and possibly a dead stick at the most at the most inconvenient time. Result..loss of model or injury, is that negligence as you knew it was not correct?


Looks ok to me!




Laser appreciation society view


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2 hours ago, Nigel R said:

Can't recall the name of it now, but they're a way you can set up a small auxiliary tank in the correct place. 


Chicken hopper?

Chicken hopper it is, works well, but the pipe flows, gradients have to be downhill towards the feed tank to the engine.

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Alternatively, use a Perry Pump to pump the fuel to the engine.  If you have a pumped engine e.g. OS120 pump you also avoid the problem of fuel tank placement.  If you are going to move the tank aft and the engine isn't pumped, then you definitely need a Perry Pump.

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Perry pumps IMO:


- good but quite pricey by comparison to the extra tank

- quite small and easy to retrofit, especially in a tight install where a tank won't fit

- not every carburetor will be 100% happy with a pump, although most twin needle can be made to work acceptably well *


* When I converted a pump engine (with a flaky pump) to regular operation, the main difference in parts was that the carb barrel was different, which had the effect of altering the mid-range running characteristics. Without the different barrel, the midrange would have been lean without the pump.

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15 hours ago, Paul De Tourtoulon said:

Or do this to it,,,


It's one of the first pictures, I have got the spray bay in line with the crankshaft in my PC-9, after putting another extension on it.

Laser mod 1A.jpg

That'll give Jon apoplexy.........😜

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