Members Letters

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" height=110 BGCOLOR="#DDDDDD" TEXT="#080000"> <bR> <div> <B> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="632" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 18 WIDTH="84"><div> <A HREF="index.htm" TARGET="_top" TITLE="Home Page"><U><B>Home Page</B></U></A></div> </tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id18.htm" TARGET="_top" TITLE="Contact Us"><U><B>Contact Us</B></U></A></div> </NOBR></tD> <tD VALIGN=TOP WIDTH="77"><div> <A HREF="id24.htm" TARGET="_top" TITLE="Map Page"><U><B>Map Page</B></U></A></div> </tD> <tD VALIGN=TOP WIDTH="92"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="18" ALIGN="bottom" WIDTH="92" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="68"><div> <A HREF="id17.htm" TARGET="_top" TITLE="Calendar"><U><B>Calendar</B></U></A></div> </tD> <tD VALIGN=TOP WIDTH="100"><div> <A HREF="id41.htm" TARGET="_top" TITLE="Flight Sim"><U><B>Flight Sim</B></U></A></div> </tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id50.htm" TARGET="_top" TITLE="Indoor Flying"><U><B>Indoor Flying</B></U></A></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 17 WIDTH="84"><div> <A HREF="id27.htm" TARGET="_top" TITLE="Members "><U><B>Members </B></U></A></div> </tD> <tD VALIGN=TOP WIDTH="77"><div> <A HREF="id30.htm" TARGET="_top" TITLE="Photos"><U><B>Photos</B></U></A></div> </tD> <tD VALIGN=TOP><NOBR><div> <A HREF="electronics.htm" TARGET="_top" TITLE="Model Electronics"><U><B>Electronics</B></U></A></div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id32.htm" TARGET="_top" TITLE="For Sale/Wanted"><U><B>For Sale/Wanted</B></U></A></div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id53.htm" TARGET="_top" TITLE="Scale Day"><U><B>Scale Day</B></U></A></div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id42.htm" TARGET="_top" TITLE="Members Letters"><U><B>Members Letters</B></U></A></div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id65.htm" TARGET="_top" TITLE="Construction"><U><B>Construction</B></U></A></div> </NOBR></tD> </tR> </TABLE></B></div> <div> </div> </td> </tr><tr> <td valign="top" height=370 BGCOLOR="#DDDDDD" TEXT="#080000"> <div> Members Letters</div> <bR> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <FONT SIZE="5" COLOR="#6633CC" FACE="Arial" ><B><U>Some Notes on Noise Reduction.</U></B></FONT><B>       </B></div> <bR> <bR> <bR> <div> <I><B><U>Summary. Please read this bit if you don't read anything else a more detailed analysis of noise reduction appears on the following pages.</U></B></I></div> <bR> <div> <B>You can reduce the sound output of your model by:</B></div> <bR> <div> <B>fitting a “soft mount” which isolates the airframe from vibration</B></div> <bR> <div> <B>fitting a larger propeller to reduce the rpm</B></div> <bR> <div> <B>fitting a propeller with a scimitar shaped blade which are quieter than those with squared-off ends</B></div> <bR> <div> <B>fitting a quieter silencer </B></div> <bR> <bR> <div> <B>A soft mount will reduce sound output by up to 2.5 dBA.</B></div> <bR> <div> <B>On a 40-61 two-stroke, 1” on the diameter, or 2” on the pitch of the propeller will reduce the revs by 1000rpm and the noise by more than 3dBA. So if your engine is too noisy, fit a bigger prop as the first step.</B></div> <bR> <div> <B>A baffled tuned pipe is the most effective silencer provided it is adjusted, i.e. lengthened, for an engine turning over at about 10,000-12,000 rpm. Most people fit small propellers and adjust the length of the pipe to allow the engine to run at much higher revs, hence the perception that tuned pipes are noisy. As an example an OS 40 SF produced an extra 6dBA at 13,600 on a Master 11x6 and a tuned pipe, compared with the same set up on a 12x6 APC revving at 11,400. </B></div> <bR> <div> <B>In the analysis summarised below an OS 61 RF, a rear exhaust two stroke specifically designed for aerobatics and fitted with a tuned pipe, managed to turn props of 12x12 and 13x10 very quietly with no loss of model performance. I'll agree that a “cooking” 61 is unlikely to be able to turn props of that size, but it should be able to turn a much larger prop than that old 11x7.Try it with a 12x8 and see.</B></div> <bR> <div> <B>Larger engines (120 plus) turning very large propellers may require further experiment.</B></div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B>Try to get the maximum revs down to about 10,000 to 12,000 and we'll be alright</B><FONT SIZE="4" COLOR="#6633CC" FACE="Arial" ><B>.</B></FONT></div> <bR> <bR> <bR> <div> <U>Introduction</U></div> <bR> <div> These notes are based on a series of experiments carried out by the late Chris Olsen in 1995 and published in RCM&E in September 1995. I believe that Chris had an engineering degree and had served as an RAF flight engineer. He was British R/C aerobatics champion in the late fifties and finished third in the World Championships in 1962 so he should know what he's talking about. The experiments were carried out using three engines, all OS two strokes, an OS40SF and an OS 46VF in an Uproar and an OS61RF and the OS46VF in an Upset, models designed by Chris in the 50's and 60's. The Uproar is a 66” shoulder wing monoplane, the Upset, a pattern ship of about the same size. All of his engines were fitted with baffled tuned pipes adjusted to operate at 10,000 to 12,000 rpm.</div> <bR> <div> Chris identified three sources of noise: engine vibration, propeller noise and exhaust noise. </div> <bR> <div> He took all his measurements at 3 metres in the interest of accuracy rather than the 7 metres which we use<U>. His benchmark was 90dBA at 3 metres which equates to our target of 82 dBA at 7 metres</U>.</div> <bR> <bR> <div> <U>Engine Vibration</U></div> <bR> <div> Engine vibration can cause noise to be amplified through “drumming” through the airframe, i.e. a light ARTF structure or a built up biplane will generate more noise with the same engine and prop, than a stiff foam veneer structure such as you will find on an Acrowot and there is little that we can do about that. </div> <bR> <div> To reduce this source of noise you could fit a “soft” engine mount. Chris experimented with four types.</div> <bR> <div> The Lord Mount. These are simply two threaded studs with a piece of rubber in between. They should be available in engineering supply shops, try Bearing Man in Harlescott. They come in various sizes and grades. Chris recommends the middle grade, 3/8” long x 3/8” diameter for models engines up to and including 61s. Anyone who has ever owned a Morris 1100 will know that the exhaust is attached to the car with Lord mounts.</div> <div> Gator Mounts.</div> <div> Weston Mounts </div> <div> Du-Bro Mounts.</div> <bR> <div> The last three types are specifically designed for model aircraft but Gator are intended for 60-1.20 cu in engines and were modified by Chris in his workshop to suit smaller engines.</div> <bR> <div> Two engines the 40 and 46 were tried in an Uproar. </div> <bR> <div> The 40 in a hard mount produced 92 dBA at 3 metres using an 11x6 Master Prop, 2 dBA above the target. By simply changing to a soft mount the output fell to 89.5dBA, slightly below the target of 90 dBA.</div> <bR> <div> By changing the prop to 12x6 APC it fell further to 89dBA at 3 metres, well below our 82dBA target at 7 metres. </div> <bR> <div> <B>3dBA might not sound much of a reduction but the decibel system is non-linear and a reduction 3dBA equates to a reduction of half the noise.</B></div> <bR> <div> The 46 produced 92dBA using a hard mount and 12x7 APC prop. With a Lord Mount it fell to 88dBA, a reduction of 4dBA and even quieter than the 40.</div> <bR> <bR> <bR> <bR> <div> <B><U>Propellers</U></B></div> <bR> <div> <B>OS 40 in an Uproar</B></div> <bR> <div> Fitting his engine with a 12x6 APC and a soft mount instead of an 11x6 Master in a hard mount reduced the noise out put from 92 dBA at 3 metres to 88dBA, well within target.</div> <bR> <div> This reduction is mainly due to the reduction in engine revs from 13,600 rpm to 11,400. The performance of the model was not affected because the larger propeller is more efficient.</div> <bR> <div> <B>OS 61 RF in an Upset.</B></div> <bR> <div> Chris tested seven propellers, all APC, from 12 to 13.5 inches diameter with pitches ranging from 9 to 12 inches. </div> <bR> <div> The quietest, a 12x12 gave a reading of 88dBA. The noisiest was a 13x9 at 93 dBA. </div> <div> A 12.5x11 and a 13x10 also produced less than the 90dBA target. </div> <bR> <div> Again the reduction in sound was mainly due to the reduction in revs, from 10,700 rpm on the 13x9 to 10,000 on the 12x12.</div> <bR> <div> <B><U>Exhaust Noise</U></B> </div> <bR> <div> Exhaust systems do make a difference. </div> <bR> <div> On open exhausts, the noise output of the OS40 measured 104dBA at 12,600 rpm at 3 metres with an 11x6 propeller. </div> <bR> <div> With the same set up but with a mini-pipe fitted, the rpm were the same but the noise output had fallen to 92dBA, a reduction of 14dBA.</div> <bR> <div> The quietest set-up, 88 dBA at three metres, was with a baffled tuned pipe, soft mount and 12x6 APC propeller revving at 11,400 rpm.  Again 88 dBA at 3 metres is much quieter than our target of 82dBA at 7. </div> <bR> <div> Tuned pipes cost £45-£75, mini-pipes up to £58, Q silencers £16-£40.</div> <bR> <div> <B><U>Four Stokes</U></B></div> <bR> <div> These are less likely to cause offence because they fire half as frequently as two strokes and emit a lower frequency exhaust note. Should you need a quieter exhaust, Just Engines produce a range of  “Super Quiet” silencers and tuned pipe systems ranging in price from £35 to £75 depending on engine size.</div> <bR> <div> <B><U>Conclusion</U></B></div> <bR> <div> <B>Since the article was written a wide variety of super quiet silencers, mini-pipes and tuned pipes have become available which reduce sound output dramatically, however, they will show little difference if you insist using small props.</B></div> <bR> <div> <B><U>Contacts</U></B></div> <bR> <div> Just Engines <FONT SIZE="2" COLOR="#0000FF" FACE="Arial" ><A HREF="http://www.justengines.co.uk" TARGET="_top" TITLE="http://www.justengines.co.uk"><U><U>www.justengines.co.uk</U></U></A></FONT> 01228 712800 for mounts and exhausts. Other products mentioned are available to order through your local model shop.</div> <bR> <div> The German Zimmermann Company also has an excellent reputation for silencers but I have been unable to find their web address. </div> <bR> <div> <B>David Davis.1st Nov. 2007</B>. </div> <div> Tel: 01743 362125. Mob: 07966 550131. Email: davedavis@ren-man.fsnet.co.uk.           <FONT SIZE="3" COLOR="#6633CC" FACE="Arial" ><IMG SRC="405283c0.jpg" border=0 width="40" height="60" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></FONT></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------</div> <bR> <bR> <bR> <bR> <div> <B>Chart   </B><B>illustrating the relationship between engine rpm and tip speed for various prop diameters    </B></div> <bR> <bR> <bR> <div> <IMG SRC="42c534a0.gif" border=0 width="595" height="842" ALT="Adobe Acrobat 7.0 Document" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <bR> <div> <B> Chart submitted by Richard Golding ,           </B><IMG SRC="3b228380.jpg" border=0 width="40" height="56" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <bR> <bR> <div> <A HREF="index.htm" TARGET="_top" TITLE="Home Page"><U><B><IMG SRC="42b3c410.gif" border=0 width="60" height="65" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <bR> <div> <B><U>___________________________________________________________</U></B></div> <bR> <bR> <bR> <bR> <div> <B><U><IMG SRC="44158c20.jpg" border=0 width="600" height="450" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <bR> <div> Top left clockwise, a Lord mount from Bearing man @ about £4 each ,   (but has very hard rubber,) a mount using 'rawlbolts' through 9mm holes, </div> <div> a 'Dubro' mount @ £30 ,and an Apache mount for larger engines -was £15 for set of four ,possibly more now. </div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B>Some Pictures of Suitable Soft Mounts/Components  By Ron Shone         </B><FONT SIZE="5" COLOR="#6633CC" FACE="Arial" ><B><U><IMG SRC="258283b0.jpg" border=0 width="40" height="59" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></FONT></div> <bR> <bR> <bR> <div> <A HREF="index.htm" TARGET="_top" TITLE="Home Page"><U><B><IMG SRC="42b3c410.gif" border=0 width="60" height="65" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <bR> <div> <B>-----------------------------------------------------------------------------------------------------------------------------------------------------------------------</B></div> <bR> <bR> <bR> <div> <B><U>DIY Futaba Cam Pack</U></B></div> <bR> <bR> <div> I recently located two useful web sites for those interested in building their own 8 memory CAMPAC for their Futaba FF8. It is quite unbelievable that for less than £2.00 plus a bit of fiddly soldering you can create what commercially cost nearly 50 quid from a Futaba supplier. The actual memory chip is only 48p ! The web sites are <FONT SIZE="3" COLOR="#0000FF" FACE="Arial" ><A HREF="http://members.telocity.com/fritzthecat/campac.html" TARGET="_top" TITLE="http://members.telocity.com/fritzthecat/"><U><U>http://members.telocity.com/fritzthecat/campac.html</U></U></A></FONT>    and <FONT SIZE="3" COLOR="#0000FF" FACE="Arial" ><A HREF="http://www.ncws.com/rcrock/clonepac.htm" TARGET="_top" TITLE="http://www.ncws.com/rcrock/clonepac.htm"><U><U>www.ncws.com/rcrock/clonepac.htm</U></U></A></FONT>. Anyone who wants to have a go can email me and I'll give them the RS Components Pt.Nos. The only thing I made up myself was the circuit board as I didn't want to spend a disproportionate amount on a commercial one. </div> <div> Regards </div> <div> Steve Allsop.    <IMG SRC="101283a0.jpg" border=0 width="40" height="58" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  <A HREF="mailto:steveallsop@churchway.plus.com" TARGET="_top" TITLE="mailto:steveallsop@churchway.plus.com"><U>mailto:steveallsop@churchway.plus.com</U></A></div> <bR> <bR> <bR> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><U> <A NAME="starting_with_helicopters"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></U></B></div> <div> <B><U>Starting with Helicopters</U></B></div> <bR> <bR> <bR> <div> Having now spent far to long learning to fly a helicopter I consider myself as an experienced novice & would like to pass on advice for anyone considering having a go. Experience with fixed wing flying only helps in that the set up of the radio gear and engine is similar, but the similarity stops there. </div> <div> To keep the cost sensible it is probably best to go for a 30 size to start with not only because they are cheaper to buy than a larger one but also the running costs & spares are cheaper as well. There are some very good helicopters around at the moment some of the popular ones being the  Raptor, Shuttle, and Nexus all around the £200-00 mark & will fly well if correctly set up. As with aero engines you get what you pay for but remember that in a helicopter your engine is everything, a beginner will not be able to auto rotate and do a safe dead stick landing so reliability is the key. Personally I think if buying new, an OS at around £120-00 is worth every penny, it is not that fussy on the mixture settings or which pipe you use and has smooth progressive power around the mid range, remembering that 90% of flying will be done at half throttle. The latest generation of heading lock giros make hovering manoeuvres easier & cost around £80-00 however the good old mechanical giros still allow good flying.</div> <div> A lot of people ask if they should buy new or second hand. New is obviously best if the wallet lets you where you have a choice of ready built models or kits. I like the idea of building myself because you know for sure that every bolt etc that needs thread lock has it & also you can choose which engine you have. It took me three longish evenings to build my Raptor. If buying second hand wiggle & jiggle everything for wear & make sure that spares are still available if an old model. Second hand would probably be a preferred option if you just want to have a go cheaply.</div> <div> Finally make sure that you have a transmitter with the necessary Heli functions & don't go wasting too much money on upgrades. Bearing & linkage upgrades are usually worthwhile but most only enhance the performance for the more experienced flyer. Make sure you get help for your first flight and read the BMFA handbook on helicopter safety.</div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div>     <B><U> Martin Oldershaw</U></B></div> <div> <B><U><IMG SRC="10928330.jpg" border=0 width="40" height="51" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></U></B></div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <div> <B><U> </U></B><B><U>Stampe SV4 a Potted History By Steve Allso</U></B><FONT SIZE="4" COLOR="#0000FF" FACE="Arial" ><B><U>p</U></B></FONT></div> <bR> <bR> <div> The SV4 Stampe first flew on 17th May 1933, with Jean Stampe at the controls. The company manufactured six SV4 trainers for use in its flying school. Production ceased in 1935 after the death of his son Leon Stampe, but two more SV4s were manufactured in 1937 having been redesigned by Demidoff with two extra ailerons, and with a changed tail section <U>.</U></div> <div> The only<U> </U>SV4 which survived World War 2 was OO-ATD.</div> <div> Postwar, Belgium and France were in need of trainers to recreate their Air Forces, and the SV4 was a logical choice considering the lack of available alloys. The state run SNCAN manufactured 701 SV4s, nearly all having the Renault 4P engine, between 1945 and 1949.</div> <bR> <div> In 1947 Jean Stampe met up again with Alfred Renard who had been with the company until 1930. Together they set up the Stampe and Renard Company in Antwerp and produced 65 SV4b aircraft with the Gipsy Major 10 engine, for the Belgian Air Force.</div> <div> France created the Societe de la Formation Aeronautique with 500 Stampes spread amongst aero clubs and National Flying Centres. The SV4 was the mainstay of aerobatic competitions until the 1960s, when the performance of Pitts Specials and other aircraft left the Stampe SV4<U> </U>behind.</div> <bR> <div> <U>The Model</U></div> <div> The model was built to ¼ scale from a Balsacraft kit. It first flew on Saturday 22nd July 2000, just  6 months after the box was opened !. The day was hot and sunny with a moderate easterly breeze.</div> <div>  A few pre take off checks proved positive so open the throttle and see what sort of mood she was going to be in. She climbed out quite straight but seemed keen to raise her nose higher than I fancied so a bit of forward stick, whilst feeding in forward trim, put her in a gentle climb. As the speed increased she tended to bank to the left a little which needed compensating with right aileron trim. All these little things happen quite quickly but she was now high and safe and looking good.</div> <div> I tested the roll rate, which for a large model was quite good, but it could hardly be called rapid. Having an aileron on each wing certainly improves roll rate but the cost is some adverse yaw despite being set up with differential movement. In pitch she was reasonably sensitive but I subsequently discovered that the engine bulkhead was becoming detached from its side walls which meant that during the latter part of the first flight she was flying with a variable thrust  line! </div> <div> The flight concluded very well with a high final approach into about 5 - 8 kts of headwind. I approached high to minimise the time in the wind gradient and also give myself a fighting chance if the donk stopped on approach.  </div> <bR> <div> This is a great kit for those who enjoy building.</div> <bR> <div> Steve Allsop     <IMG SRC="101283a0.jpg" border=0 width="40" height="58" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><U>Fokker D-7 by Lawrence Drennan</U></B></div> <bR> <div> Fokker D-7, serial 382/18, crash landed 17/6/1918, after simultaneous attack</div> <div> from British 3 SE5's, in a dog fight of 19 German and 15 British Aircraft.</div> <div> Pilot was Ltn. Kurt Wusthof, 27 victory Ace who, survived with a painful</div> <div> groin injury. Jasta 15 red and blue fuselage colours were painted in the</div> <div> field.</div> <bR> <div> Model quarter scale, scratch built, 10Kg weight, 89" span, Zenoah 38 + scale</div> <div> exhaust.</div> <bR> <div> Maybe too many words, but this plane had a fascinating story-hope this is</div> <div> OK?</div> <bR> <bR> <div> Lawrence</div> <bR> <bR> <bR> <bR> <bR> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <B><U>CRASH DAMAGE</U></B></div> <bR> <div> It just goes to show there is always something lurking to catch us modellers out.After 20 odd years of flying I was almost caught out by a faulty receiver after a recent accident     (OK then crash).</div> <bR> <div> A Cap 232 I was flying had a premature meeting with the tarmac ( carrier bag job ), anyway after stripping it all down and coming to the conclusion it was pilot error I tested all the radio equipment for damage, after checking the Aerial was still secure and there were no bits missing from the receiver the switch harness was ok servos all checked out and range test completed I decided it was serviceable and installed it all into a nice shinny new Cap 231, again once installed a range check was carried out -all appeared hunky dory after several sessions on the kitchen table waggling the sticks about and annoying the wife it was time to fire up the motor. The motor running like a good un I was taxing up the garden when the throttle blipped and the model went haring towards the conservatory lucky the throttle came back to tick over just before disaster, on inspection with the motor running it was found any knock on the fuzz or increase in throttle caused radio interference, after checking for metal to metal etc and stripping the radio out I removed the crystal and there was the problem one leg of the crystal had sheared off but was still making intermittent contact until the vibration from the motor caused intermittent disconnection's.</div> <bR> <div> This is something I've not had happen before but it is worth a check periodically, Two minutes checking could save a few hundred quid.</div> <bR> <bR> <div>           Carl Gittins.  <IMG SRC="13c283a0.jpg" border=0 width="40" height="58" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <bR> <bR> <DIV ALIGN="LEFT"></DIV> <div> <A HREF="index.htm" TARGET="_top" TITLE="Home Page"><U><B><IMG SRC="42b3c410.gif" border=0 width="60" height="65" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> <bR> <bR> <bR> <bR> </td> </tr></table></body>