Archive/Old Mag/CAP 21 Part2

<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>Archive </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="id52.htm" TARGET="_top" TITLE="Archive/Old Mag/CAP 21 Part1"><U><B><< </B></U></A><B>  </B><A HREF="id78.htm" TARGET="_top" TITLE="Archive/Old Mag/CAP 21 Part 3"><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=TOP HEIGHT= 1496 WIDTH="550"><div> <I><B>CAP 21 - Part 2</B></I></div> <bR> <div> We finished part 1 at the radio installation stage.</div> <bR> <div> The radio gear went in with no trouble. I used a Futaba 148 on throttle. Two Hitec HS 700's were used on rudder and elevator; these have an output torque of 9.5 Kg cm at 4.8 volts. The rudder uses a closed loop system which is light, positive and slop free and was also easy to set up. I couldn't really use closed loop on the elevators as this would have cables showing on top of the fuselage. A pushrod system could not be used either because the width of the fork to both elevator halves would not have passed down the inside of the fuselage. I thought about using a heavy duty Sullivan cable but<FONT SIZE="2" COLOR="#006600" FACE="Arial" ><I><B> </B></I></FONT><IMG SRC="324ed370.jpg" border=0 width="237" height="311" ALIGN="LEFT" HSPACE="5" VSPACE="5">the weight of the wire joiner for the elevator halves put me off a bit, and being as the fuselage and fin were already assembled how could I bend the wire after passing it through the fuselage? It'd be a minimum of 10 gauge don't forget. So decided to fit a heavy duty cable to each elevator half and using a "T" joiner at the servo end with a big ball joint onto the servo arm. This method is probably lighter than a pushrod with 3mm wire rod ends, and lighter than a single cable with a large wire diameter joiner between the elevator halves. It seems to work quite well although there is a little "rattle" in it.</div> <bR> <div> The ailerons employ pair of Hitec HS 605's. These have an output torque of 5.5 Kg cm at 4.8 volts and are the same size as a standard type servo. One is installed in each wing panel at getting on for half span.</div> <bR> <div> One problem I've had throughout the radio setting up is what amount of surface movement to employ. I've set the elevators to about 25 degrees total on low rate and the same for aileron. Rates off is about double that. Rudder is everything I can get! Fingers crossed there then!</div> <bR> <div> Transporting these larger type models can be a pain but I managed to get the thing in my little Peugeot 205 with a little effort. It's amazing just what you can get in these little cars. I tried getting it in a 309 too, but it wouldn't go in because of the way the rear seats fold, even though the 309 is a bigger car. </div> <bR> <div> By the time I got it to the flying field we were in muddy November. I'll have to make something to rest it on at the field while I fit the wing as turning it on it's back results in crushing the canopy! So I had to try and balance it on the spinner and fit the wing, sheeez! A proper pain! Carrying the thing up to the strip was hard labour too! I couldn't drag it on it's wheels because of the mud packing inside the spats. Once there I got one of our members to have a go at starting it. He'd owned a ST 3000 before and so was confident. I wasn't for sure! We gave it a good prime and he kept turning it over gripping the prop' firmly 'till he felt it begin to kick. A little after that with a few smart flips from a chicken stick and it was running at last. (Thanks Pete!)<FONT SIZE="2" COLOR="#006600" FACE="Arial" ><IMG SRC="3253ad10.jpg" border=0 width="314" height="209" ALIGN="RIGHT" HSPACE="5" VSPACE="5"></FONT></div> <bR> <div> I had the model tethered with a beautifully made canvas strap around the tail anchored to a metal stake. (Thanks Eddy!) At half throttle there was so much pull I thought it'd rip the tail off! What power! Anyway, we ran a very, very rich tank full through it and all was well. On the second tank I was building up to full throttle in bursts. Everytime I did this as we got to full throttle the engine would go into a full two stroke. I kept winding the needle valve out but still I couldn't get it to continue four stroking at full power. I finally ended up with the needle valve running of it's thread! So definitely a problem of some sort then, dammit! While it was running I was absolutely bursting to fly it...</div> <bR> <div> A lot of head scratching went on about this problem. Was the fuel tubing bore too small perhaps. Most thought it was unlikely. Several different carb's have been fitted to these engines during their lifetime but after numerous phone calls and e-mails all I got were assurances that, yes, it would run very well on the ST G20/23 carb'. In the end I decided to remove the engine and tank for inspection. I got the whole thing apart and just sat there staring at it. Everything was fine. Perfect in every way. What on earth was wrong? </div> <div> <IMG SRC="3263af40.jpg" border=0 width="314" height="244" ALIGN="LEFT" HSPACE="5" VSPACE="5"></div> <div> I was about to give up in despair and was just really messing about when I decided to blow down all the fuel tubing. I noticed immediately that the actual feed pipe to the carb' was far more restrictive than the other pipes. In the feed pipe was a fuel filter. (See Photo') It was a machined alloy type that I use and they are beautifully made. Inside is a very fine nylon type screen. I'm sure that this is what the problem is; it just can't pass enough fuel at full throttle. Another lesson learned. The fuel feed pipe is as free as the others without the filter so it must have been the problem. </div> <bR> <div> By the time I'd tracked this down we were well into winter and the field had become even muddier so I postponed test flying 'till next spring. Next time, test flights! <I>G :-)</I></div> <DIV ALIGN="LEFT"></DIV> <div> <A HREF="id78.htm" TARGET="_top" TITLE="Archive/Old Mag/CAP 21 Part 3"><U><B>(Goto Part 3)</B></U></A></div> <div> <I>FF-13-03-02</I></div> </tD> </tR> </TABLE></div> <div> <A HREF="id52.htm" TARGET="_top" TITLE="Archive/Old Mag/CAP 21 Part1"><U><B><< </B></U></A><B>  </B><A HREF="id53.htm" TARGET="_top" TITLE="Archive/Old Mag/Your Eyesight"><U><B> </B></U></A><A HREF="id78.htm" TARGET="_top" TITLE="Archive/Old Mag/CAP 21 Part 3"><U><B>>></B></U></A></div> <bR> </td> </tr></table></body>