Reference/Fuel Tank Positioning

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" rowspan="2" width=156 BGCOLOR="#FFFFFF" TEXT="#080000" bgproperties="fixed" background="00e9cc00egerdp.jpg"> <div> <B> <STYLE>  </STYLE>  </B></div> <bR> <bR> <bR> <bR> <bR> <div> <B> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="1" WIDTH="97" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 313 ><NOBR><div> <A HREF="index.htm" TARGET="_top" TITLE="Home Page"><U><B>Home</B></U></A></div> <div> <A HREF="id2.htm" TARGET="_top" TITLE="Archive"><U><B>Archive</B></U></A></div> <div> <A HREF="id5.php" TARGET="_top" TITLE="Contact"><U><B>Contact</B></U></A></div> <div> <A HREF="id6.htm" TARGET="_top" TITLE="Downloads"><U><B>Downloads</B></U></A></div> <div> <A HREF="id7.htm" TARGET="_top" TITLE="Events"><U><B>Events</B></U></A></div> <div> <A HREF="id8.htm" TARGET="_top" TITLE="For Sale"><U><B>For Sale</B></U></A></div> <div> <A HREF="id9.htm" TARGET="_top" TITLE="Galleries"><U><B>Galleries</B></U></A></div> <div> <A HREF="id14.htm" TARGET="_top" TITLE="Games"><U><B>Games</B></U></A></div> <div> <A HREF="id15.htm" TARGET="_top" TITLE="Links"><U><B>Links</B></U></A></div> <div> <A HREF="id16.htm" TARGET="_top" TITLE="Magazine"><U><B>Magazine</B></U></A></div> <div> <A HREF="id17.htm" TARGET="_top" TITLE="Newsletter"><U><B>Newsletter</B></U></A></div> <div> <A HREF="id18.htm" TARGET="_top" TITLE="Reference"><U><B>Reference</B></U></A></div> <div> <A HREF="id88.htm" TARGET="_top" TITLE="Video"><U><B>Video</B></U></A></div> <div> <A HREF="id19.htm" TARGET="_top" TITLE="Weather"><U><B>Weather</B></U></A></div> </NOBR></tD> </tR> </TABLE></B></div> <bR> </td> <td valign="top" colspan=2 height=100 BGCOLOR="#FFFFFF" TEXT="#080000" bgproperties="fixed" background="00f00640egerdp.jpg"> <bR> <bR> <bR> <div> <I><B>Reference</B></I></div> <div> </div> </td> </tr><tr> <td valign="top" height=380 colspan=2 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <FONT SIZE="2" COLOR="#000000" FACE="Arial" > <STYLE>  </STYLE>  </FONT><A HREF="id68.htm" TARGET="_top" TITLE="Reference/Fuel Facts by Don Nix"><U><B><<</B></U></A><B>    </B><A HREF="id70.htm" TARGET="_top" TITLE="Reference/Fuel Tanks Twin"><U><B>>></B></U></A></div> <div> <TABLE BORDER="0" CELLPADDING="25" CELLSPACING="1" WIDTH="602" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=CENTER HEIGHT= 1446 WIDTH="550"><div> <B>Fuel Tank Positioning</B></div> <div> There's a lot of rubbish talked about the positioning of fuel tanks in a model. The important thing is to keep the fuel "head" as small as possible. If the fuel head is too low then the engine has to draw fuel uphill. The result is to begin the flight with the perfect mixture, but as the flight progresses and the tank empties the fuel head gets lower and the engine runs increasingly leaner until it begins to sag in the climb or even quits altogether.  It's not good for your nerves and it isn't good for your engine either. You've got to get the tank as close as you possibly can to the engine and line it up properly with the carburettor. The ideal position is shown in Fig' 1 for upright engines and Fig' 1a for sidewinder. This will give the absolute minimum fuel head.</div> <DIV ALIGN="LEFT"></DIV> <div> <IMG SRC="37197af0.png" border=0 width="407" height="175" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> You can see from these two pictures that whatever position your aircraft is in you'll have the minimum fuel head that's possible. This is the ideal setup for aerobatic aircraft as the fuel head remains the same upright or inverted. As most model aircraft are taildraggers with the fuselage at an uphill angle on the ground, you don't often get the fuel draining into the engine by gravity. If you do, take a look at Fig' 3.  It's best to arrange your fuel feed like this in any event.</div> <DIV ALIGN="LEFT"></DIV> <div> <IMG SRC="37298a90.png" border=0 width="408" height="169" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> If you fly a high wing trainer type it may not be possible, or even desirable, to use the above set up, especially if it has a tricycle undercarriage, which gives the fuselage a slightly nose down attitude. Fuel can easily drain into the engine and cause flooding at start up quite quickly. As this type of model is not required to fly inverted for any length of time it's probably better to use the setup in Fig' 2. It's tried and tested and does work well, but you can see what would be happening if the model were inverted! Just make sure you're running a little rich at take off with a full tank. An exhaust pressure feed will also reduce the fuel head in all cases. Although it can be a waste of time on four stroke engines which seem to have few fuel draw problems.</div> <DIV ALIGN="LEFT"></DIV> <div> <IMG SRC="373a5af0.png" border=0 width="421" height="175" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> Remember, lean running is an engine killer; don't do it! Especially in these days of fuels with synthetic oil! I see plenty of people ruining expensive and desirable engines by running to lean and then moaning about how engine xxxx are a load of rubbish! If you can't get your tank near the desired position then have a little thought for your engine and give it an easy time toward the end of your flight. It's not just the engine you're going to lose by running lean if it quits at an awkward moment.  Whichever way you look at it running lean COSTS! A rich motor will rarely quit..... or wear out!</div> <DIV ALIGN="LEFT"></DIV> <div> <IMG SRC="374a3c00.png" border=0 width="419" height="192" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> <B>Remember the golden rules: </B></div> <div> <B>Don't have a tank that's too big. Aim for a flight of around 15 minutes.</B></div> <div> <B>Do get the tank as close to the engine as you can.</B></div> <div> <B>Do get the tank as close to Centre carb' to Centre tank as you can.</B></div> <div> <B>Do insulate the tank from vibration as much as you possibly can. </B><I>G :-)</I></div> <div> <I>FF-28-11-01</I></div> </tD> </tR> </TABLE></div> <div> <A HREF="id68.htm" TARGET="_top" TITLE="Reference/Fuel Facts by Don Nix"><U><B><<</B></U></A><B>    </B><A HREF="id70.htm" TARGET="_top" TITLE="Reference/Fuel Tanks Twin"><U><B>>></B></U></A></div> <bR> </td> </tr></table></body>