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In an airframe it's a different matter, but the issue is the *variation* in fuel head affecting the mixture rather than the ability to pull the fuel to to carb.
Quote from: Allen Smithee on August 09, 2014, 02:00:38 PM In an airframe it's a different matter, but the issue is the *variation* in fuel head affecting the mixture rather than the ability to pull the fuel to to carb. Are you not familiar with the 'uniflow' tank set up Allen? Gives a very consistent run without pressure too.
Yes, it minimises the variation in head as the fuel level drops in the tank but it won't correct for the variation between upright and inverted from a tank that's (say) 1" below spraybar height. Most of my stuff ran on either pipe pressure (around 3psi) or untimed crankcase pressure (up to around 11psi, but varies with mixture setting). Most modellers don't actually realise that the reason for running pressuresed fuel systems isn't to push the fuel into the engine - it's to provide a high pressure "bias" so that the variations due to changes in head when manoeuvering are a small proportion of the overall pressure at the spraybar, thus minimising mixture changes. That's why you never see a CL stunt engine running anything but suction feed - these variations in pressure are actually *used* to kick it from a rich 4-stroke in level flight to a lean 2-stroke though manoeuvers.
Yes, you don't want this happening
What I am interested in is the dimensions of that engine clamping arrangement. Is it about 150 to 200 mm wide? What is the height of the clamping blocks?