Merco 61

Hello, I,m not well versed with electric power.I have a nice old Graupner Cirrus and have been thinking of mounting a geared motor in the nose.I have a Kontronic Fun480-33 with gearbox and Jazz 40-6-18 esc..Would probably look for a 14x10 folder and 3 cell 2200 lipo.Am I likely to achieve safe self launching using this combination please ?

Thanks for all tips,much appreciated.Yes,did note the invisible circlip.The self tapper extractor worked a treat and gudgeon pin slid out easily. Whilst in Boots,I noticed a cheap DIY dentistry set,comprising a probe shaped like a shepherds crook ,and a little mirror and scraper.The probe,which is of very tough steel,was ideal for wrinkling out the circlip and cleaning out its groove.No use yet for the mirror.Shaft bearings both out without too much drama so should be plain sailing now.Thanks again

Hello, I,m in the process of renewing shaft bearings on an old but fairly good OS 120 Surpass .The gudgeon pin is firmly seized in the piston bearings.I stupidly allowed the liner to slide out so piston is no longer supported.Obviously liner cannot be replaced until gudgeon pin is removed.As only access is via hole at rear of crankcase,a rather difficult engineering challenge.I need to revolve the pin back and forth to release the seizure.I wonder if a suitable sized taper tap,sacrificial,could be carefully wound into the pin to give some turning power?The pin seems to rotate OK in the small end bearing.Any suggestions appreciated.

Very interesting thread,I thought post by Peter Christie was the definitive answer to a perrenial problem but......still not quite clear.A single cell nicad or nimh delivers 1.2 nominal(1.3 ish fresh off charge) reducing a bit dependant on length and thickness of plug lead.Plugs are sold usually for 1.5 to 2 volts,so,from the beginning,voltage is barely enough,from single cell.In my experience the degree of visible glowing varies a great deal depending on make and age ,from the same power source,2 stroke or 4.I,ve tried a number of glow sticks too,and do not trust them.Similar variations when using 12 volts through a power panel.Tom Sharp 2 talks about a 2 volt lead acid accumulator,ideal apart from risk of spills.In my impoverished youth,it was common to take Dad,s wood saw and cut a cell off the end of a car battery,with self tappers for terminals.Worked fine and never needed charging..My favourite at the moment,is a Ripmax 2v 4ah No.0PRP0204 sealed lead acid,about the size of a cigarette packet,fromSussex Models,I think about £7 plus a little charger and ammeter from the bits box.With this elementary rig,I no longer find it necessary to remove the plug for visible check on brightness,which was a regular annoying chore with the more sophisticated systems tried,especially in a cowled engine situation.I think I will stay with it from now on.

Thanks a lot for your help.Should now be able to proceed. Quite a significant model really,probably the first rc model to perform proper controlled rolls(1958) in competition,despite excessive dihedral by modern standards..OS 61 Blackhead going into mine. Cheers.

Hello, I,m restoring a much molested old Astro Hog from Flair kit.Tailplane is missing. Does anyone have the plan.I just need the basic tailplane dimensions and centre sweep angle,as it will be cut from sheet balsa. Hope some kind person can help.

To Cold Lazurus, Thanks for reply.I followed your instructions,worked first time,so great joy in the workshop.Very grateful to you.I hope that you will soon be warm and fully risen.

Thanks for all the replies.Cold Lazarus,yours is the answer I was really hoping for and set out exactly as all instruction books should be.I,m very grateful.Would you be happy to answer further programming queries via pm? Regarding some of the other comments,we all know that any spinning propellor is inherently dangerous,petrol ,glow or electric and I,be had my fair share of cuts and bruises over the decades,despite always taking the utmost care.Engines have to be carefully tuned and at some stage all have to be tested for maximum power,so need restraining.At our club,heavy steel yokes are provided at each starting bay,great,but all thrust loads are born by the tailplane only so not perfect.Thrown props,usually from big fourstrokes, is an undeniable hazard and I have no answer to this.Go to any full-size flying club and you will see 100 hp aero engines being swung by hand,the aeroplane is unrestrained and unchocked,the prop swinger trusting that the pilot really has got the mags switched off.I doubt if it is possible to achieve total safety with our models,all we can do is do our best to anticipate the possible dangers and learn from mistakes,ours and those of others.Which is why l recounted the two incidents.

I do understand the need to instruct the tx,it’s the route and sequence that I cannot find.This all arises out of two events that happened whilst testing models in the garden.Big scratch built Piper Cub,tail firmly roped to tree.Opened up to full power for a few seconds,tailplane joint failed,models shot forward,demolishing large shrub,cowl and uc.All over in an instant.Then a 1/4scale SE5,33cc petrol,tethered with four ropes at full power,throttle failed to operate when a ball joint came adrift.External simple manual switch easily accessible so no harm done,but a daunting moment nonetheless.Yes,a bit belt and braces,but I still want a kill switch for emergencies.

Thanks Ken,will look it up.Bucksboy,it is an opto switch connected between rx and electronic ignition box which,when triggered from tx,cuts power instantly,hence kill switch.I want it as a panic button in addition to normal failsafe.I fully admit to having a mighty struggle with most computer tasks,especially programming.So far,the system will not recognize the switch which is plugged into a spare rx input.

I am trying to operate an RC exp V2.0 kill switch from my Aurora.My computer skill is very low,Ive been trying fo hours,been through the book,no success.Can anybody tell how to do it please.

What about the lovely aroma of that big stack of fresh balsa and ply.? Or peeling open some new 10a blades and prepping the sanding blocks,cleaning off the building board and sweeping up in readiness to embark upon making the best one yet? I must have built hundreds of models over the last 65 years and the buzz at starting a new one has not lessened and,I hope,never will.

Thanks for your help, will look out for the helicoil ads on BMFA.Have found some JB Weld locally and will give it a try. Ace,I now remember why we dumped the horsehair blankets.

My latest unmissable eBay purchase and bargain.OS 120 .Exhaust bend loose in cyl head,closer examination seems to indicate it had been glued in.Threads in cyl head very worn.New head too expensive .Any suggestions for a high temp compound that might give a fix,albeit a once and for all,never unscrew again solution.

Hope this question is not interrupting the flow too much.I am about to swap out a much longer engine and replace it with my Laser v200.It will entail a1.5 inch spacer of some sort.Ive made up ally standoffs and long bolts in the style of many modern petrol engines,but it looks rather ungainly and I,m a bit concerned that I might be putting the Laser mounting lugs at risk in the event of a noseover into the rough.Would appreciate your views.Thanks.