Archive/Old Mag/Mini Limbo

<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="id92.htm" TARGET="_top" TITLE="Archive/OldMag/Xtreme 3D Follow Up"><U><B><< </B></U></A><B>   </B><A HREF="id86.htm" TARGET="_top" TITLE="Archive/Old Mag/Simple G"><U><B>>></B></U></A></div> <bR> <div> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="1" WIDTH="602" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 2069 WIDTH="596"><div> <I><B>Mini Limbo</B></I></div> <bR> <div> <IMG SRC="2f238e80.jpg" border=0 width="312" height="232" ALIGN="LEFT" HSPACE="10" VSPACE="10">A friend gave me an electric fun fly model in poor condition. It has a beautiful "geodetic" type structure that must have involved a considerable amount of work for the designer/builder to produce. The fuselage was just a couple of rails of spruce with Warren girder between then sheeted over; all radio hanging out in the breeze.</div> <bR> <div> I decided to build a "proper" fuselage for it as I intended to fit a glow engine. I figured the whole thing would weigh around 2 to 2 1/4 lbs and thought an OS 25 FP would just about be enough to prop' hang it. Deciding on moment arms was a little tricky as the wing has an AR (aspect ratio)  of  2.66:1. The span is 36" and the chord is 13.5". The airfoil is a semi-symmetrical section just like a Limbo Dancer. </div> <bR> <div> I decided to make a smaller version of the Limbo Dancer fuselage as it is very simple to build and is both light and strong and has only one former in it, and that carries the engine! The plywood radio tray and wing dowels serve to stiffen it in torsion. I was suprised to find that once calculations were complete, that the fuselage length would only be 3" shorter than the original Limbo fuselage. So there wouldn't be much weight saving there then! I had to increase the tail area by about 13 sq ins and this was achieved by simply gluing a 13x1 inch strip of 3/16" balsa to its leading edge. The tail is also of a geodetic structure and the addition of the solid leading edge stiffened it nicely. Also increased the fin area slightly.</div> <bR> <div> Fuselage construction was simple and soon completed. The wing and tail surfaces were already covered in transparent red Solarfilm, so I covered the fuselage and other solid bits in solid red. The <IMG SRC="2f338d50.jpg" border=0 width="312" height="213" ALIGN="RIGHT" HSPACE="10" VSPACE="10">wingtips had been left as just two solid bits of 3/16" balsa sticking out of the ends of the wing, so I covered these too, and what a lovely shape they became. The end result looked pretty smart. Made an undercarriage up from 12 gauge piano wire. I could have saved a bit of weight here by using 14</div> <div> gauge for one of the legs as it's very strong in all 12 gauge. Fitted a pair of those foam wheels that weigh about an ounce.</div> <bR> <div> The radio consists of five SD200 micro servo's, a 600 mah NiMH battery and an old Futaba 118F receiver.  Closed loop was used for the tail surfaces and was quick and easy to set up. I installed a OS 25 FP engine fed by a 4 oz tank. All up weight was 2 lbs 2 ozs.</div> <bR> <div> First flights were pretty hopeless by any standards. It flew fine but was extremely slow. The take off roll was long. However, it had good control harmony and plenty of response. Loops were very tight with flaperon mixing and nearly as tight without it. After half a dozen tanks of fuel with the engine nicely run in, a few prop' hangs were tried. It seemed good in the hover, better than the Limbo, but with insufficient power. It'd slide back after a few seconds and there was no reserve to climb away. This was very disappointing as more power would mean more weight. </div> <bR> <div> I had a brand new MDS 28 and so, despite the extra 4 ozs in weight, I decided to fit it. It moved the CG forward about an inch and increased the all up weight to 2 lbs 6 ozs for a wing loading of 11.25 ozs sq ft. I thought it would ruin the flight performance but decided to try it anyway. </div> <bR> <div> <IMG SRC="2f438100.jpg" border=0 width="312" height="272" ALIGN="LEFT" HSPACE="10" VSPACE="10">Next day, after a couple of tanks of fuel through the engine, it was time to see.... I opened her up gently and she positively shot off across the strip and was airborne in a few feet. This looked promising! I throttled back and flew around gently to get the feel of things and was amazed to find that very little had changed despite the more forward CG and the extra weight, apart from the fact that she'll go like hell of the night now. The loops were not as tight, true; and you couldn't slow her down quit so much, but this could be compensated for by continuing to pull the nose up and balancing more power against the increasing drag and still being able to kite on the breeze. Time to try the power; pull up and apply full throttle. Wow! She goes up like a missile! Prop' hanging was transformed and she hangs on true half throttle with lots in reserve to climb away if things go pear shaped. Once again then, mission accomplished. She's a useful little tool and lots of fun and cheap to run too. She vanishes in the smallest boot and I'm really glad I bothered to do it! <I>G:-)</I></div> <div> <I>FF-05-08-02</I></div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <I><B>Much Later...</B></I></div> <bR> <div> Fast forward three years and my son, who has had the model hanging on his bedroom ceiling since 02, was beginning to get the bug after flying night after night on my latest toy, Aerofly Pro Deluxe flight simulator. He'd gotten really good with a 1/3 scale Extra and was prop hanging and torque rolling with ease and throwing the thing all over the sky, always finishing with a lovely landing. I didn't think he'd have much trouble flying the real thing.</div> <bR> <div> <IMG SRC="19f3acc0.jpg" border=0 width="314" height="204" ALIGN="LEFT" HSPACE="5" VSPACE="5">One Friday, during a period of fine weather, he asks if he could come flying with me on Saturday and maybe have a stir on the sticks. I say, "We can do better than that son. Why not charge up that Mini Limbo hanging on your ceiling and give that a blast?". Well, his face lit up because he'd always loved it and soon the Mini was checked out and on charge. </div> <bR> <div> At the field on Saturday I took the mini up and trimmed it out and handed the tranny to son. After standing next to him for five minutes or so I figured he was okay as he was buzzing around flying circuits in both directions and with the odd loop and roll thrown in. I asked if he was okay so I could go back to the car and rig my model, "Sure, Pops, no problem.", was the reply, so off I went. As I arrived at the car I was just thinking how marvelous flight simulators were when I hear an increasingly high pitched scream followed by the inevitable whump! Son had stuffed it! I ran back over to the strip to find the model in bits with the wing well and truly smashed and son absolutely mortified. He gotten inverted and disoriented and lost it completely. </div> <bR> <div> <IMG SRC="19e3ac40.jpg" border=0 width="314" height="196" ALIGN="RIGHT" HSPACE="5" VSPACE="5">"Jeez, Dad, it's nothing like the simulator I just lost it completely and froze up! I just couldn't think what to do!"  He was really upset about it and was in a morose mood for the rest of the day. I'd never seen him so upset. That night I decided I'd have a day off and see if I could repair it for him before he came home from work, although I had doubts I could acheive it. Anyhow, long story short, I did do it and had it sitting on the bed in his room when he got home. The look on his face was worth all the effort, to say he was chuffed is an understatement, he was over the moon with it, especially the bling! Kids, eh?! <I>G:-)</I></div> <div> <I>FF-8-5-05</I></div> </tD> </tR> </TABLE></div> <div> <A HREF="id92.htm" TARGET="_top" TITLE="Archive/OldMag/Xtreme 3D Follow Up"><U><B><< </B></U></A><B>   </B><A HREF="id86.htm" TARGET="_top" TITLE="Archive/Old Mag/Simple G"><U><B>>></B></U></A></div> <bR> </td> </tr></table></body>