Peter Coombe

Hi Craig,Is your Mosquito project still ongoing?I,m building the smaller BT version,or,to be accurate,trying to complete one largely built by Peter Cook. The uc assembly was made for Peter by a model engineer.Sadly ,the engineer is no longer with us,so no repeat possible. I have to confess that getting it to work and lock properly has been one of the most challenging and frustrating tasks in 60 years of aeromodelling. Looks impressive-beautiful metal-work-cannot bring myself to sheath it in balsa just yet- but every aspect of installation,mounting and adjustment is critical in the extreme.It is now working so remaining wood work can progress.Just adds to the respect due to Brian for his incredible modelling skills.Were I starting the model from scratch,would certainly look at simpler alternatives,perhaps these new electric units eg E-Flite might provide theanswer.Havent actually seen them in the flesh though.  Peter

I am ,of course ,aware that the earth should go to engine mount/crankcase.To clarify-if the collet is not tapered in width,it could bridge/ short between centre terminall and plug body. Small sleeve of fuel tube is just to increase grip on terminal even further and provide something to get hold of to pull socket off when necessary.A fibre washer betwee collet and body would also work but would be easily lost ,especially when engine is inverted.

Someone was asking for suggestions re glow plug connector.This solution works well for me.Example:Four stroke engine,fully cowled,plug inaccesible:Forget springs and popper studs.Raid your box of collets that came with mini-drill,search until you find one that fits tightly onto plug centre terminal.Plug terminals are not all the same dia but the split collet will accomodate.File/grind tip of collet to a taper so that it cannot short on plug body.Solder short length of silicon covered wire into bore of collet and support with a bit of fuel tube and heat shrink for neatness.Then connect to usual jack plug socket.If you are reluctant to sacrifice the collet,a cross cut down a short piece of thick walled brass tube with an Xacto or piercing saw works almost as well but not so sturdy.For what its worth.

Very interesting.Its really all a question of preference isnt it?Or perception of "fit for purpose".Is a 100mph electric' jet 'with factory fresh 9g servos(priced at £2 each) a less threatening proposition than-say a lovingly built, long term, trad built scale model,modestly powered and cautiously flown with older but tried and tested(and trusted)gear? I HAVE lost two models to modern cheap servos-both traced to lousy soldering of leads to pc board. On the other hand,I have some £5 standard jobs,from China, that will break your wrist if you try to manually restrain them,fantastic things.I appreciate that flyers involved in extreme aeros,with big surfaces and a violent and high stress flight pattern,have specialised needs,presumably only the best will do. Likewise,turbines and the real biggies.Its just that there are SO MANY and varied servos on offer.How does the punter know the good from the not good? Only an idiot would take a deliberate gamble with ANY part of the radio link,it is,a question of risk assessment. I ride a 79 Guzzi,had it from new,my son rides a Honda Fireblade.Technology cannot be compared,the Honda is lightyears ahead in every possible respect.Still prefer the Guzzi,even though it does get a bit sluggish around 120 per and have no plans to dispose of it. Old is not necessarily bad.Dont worry,Bravedan,have no plans to fly my old stuff anywhere near the club field.

Thanks guys,some useful and reassuring opinion garnered.Tom,if the capacitors are on their way out,would there be any visible evidence eg white deposit on "leg"?In any event,they all work well,have been given the old 100 full deflections each test,so will use them.  The flood of minute servos,some with most impressive torque figures are very tempting arent they.Cheap to the point of throwaway,easy to install fit into tiny places,,high volt tolerance-we,ve never had it so good.Or have we. It will not have escaped us that they seem to be mostly marketed in conjunction with parts for small electric powered aircraft and this has obviously become a huge market .And all great fun,I,ve tried a couple.My bridle was sharply yanked when I installed a couple of (quality) minis into the wing of my almost finished 78"Stuka- minis necessary owing to space constraints.I stripped both sets of gears in quite short order just through usual workshop clumsiness.The collisions with obstacles werent particularly violent,I had just failed to adjust to the need for much greater care and attention when small servos are installed.Would have got away with it with standards-much more ding tolerant.I,ve just ordered some sturdy looking replace ments from BRC,but have stuck to nylon gears.By the way,I know of a very accomplished and competent modeller who installed standard JRs in a 60cc petrol Spitfire which has flown regularly and spectacularly for almost TWENTY YEARS and the servos have never needed replacing.Perhaps some of us worry too much,and £170 digitals are not essential for successful flight.

I have a number of unused servos from the mid 80s,Skyleader and Kraft.All were pretty expensive when I bought them.Most are ball raced and are assembled with ICs in circuit,and,I would guess,carefully hand assembled.They work well.Should I trust them? Seems a shame to bin what were,at the time among,the best available, in favour of a bewidering choice from the baffling array of incredibly cheap PRC products..Also can someone tell me what is meant by "metal gear"servos.Are the geartrains of brass,steel or what. How good is the quality of the gears?If you stub the control surface on the car door frame,what breaks first,the surface or the servo gear.Are there any plusses.?Thanks.

Aidan,Be guided by Timbo as far as electrics are concerned.Certainly,a brushless set up,correctly propped and with a big Lipo,plus some lead ballast would yield a far superior performance.Mine was done as per because I had all the necessary kit to hand and,at the time,four new motors plus four escs and big Lipo were out of the question.Much cheaper now,of course.If you go the "stock"route,remember to include an extra wire with the supplied harness to permit brushless upgrade later.Bomb-bay?I dont think so.Keep everything as light and as simple as you possibly can.Leave bombing to the big ones.The Lanc  is only a little model and the wing loading is plenty high enough,but manageable.It must balance exactly as instructions.If you make every effort to keep the tail light,all will be well.Cut a hole in the bomb-aimers front moulding to allow air to flow through fuselage and help cool battery/esc if you go stock.You will probably be quite surprised by how much thrust those little motors and tiny props deliver.I certainly was.Good luck.  

Aidan,I have one of these.Builds into a very nice model which flys well and is very easy to handle.Sounds nice too.I am a trad modeller so finished mine exactly as per instructions/tissue dope/lightly sprayed in Spectrum.Rudders not needed.Hand launch easy.I discussed the question of swapping the brushed 400s for four brushless+four escs with the designers.Their advice was:no advantage!You will always need a hefty weight in the nose so fit the largest capacity Nimhs/nicad pack you can find."I fly with 3300s.This yields spot on CG balance, which is vital but not particularly critical,ample power and reasonable duration. There are no practical or efficiency advantages in fitting three blade props-the tiny ones supplied are very efficient and well proven.They are cheap,as are the motors.I admit that nice scale,blunt spinners would improve static appearance enormously,but to date,too many other projects have got in the way of this.I may mould some ,as I did the exhaust stacks,but they would probably be just for show as it is difficult to get a fitting around the Gunther hubs. I have a mag,somewhere,I think by that great expert,Nigel Hawes.Pretty much echoes the forgoing.Will try to find it for you. Quite sure that electric enthusiasts will argue with some of the above.I wont get involved-I am a piston man. to the core. I do know that if the model is built as per,you will get a light,cheap Avro Lancaster which would be near impossible at this size with ic engines.Keep it as light as possible,balance exactly,keep all manoeuvres smooth,no violent speed scrubbing turns.You will like it.   

Brian,Thanks for the information.Off to Maplins.Will report back in due course.Or give up and screw in a good reliable four stroke!

Have at last found instruction leaflet for above mentioned gizmo.It is a small sealed,purpose made item from Larry Davidson-US specialist in vintage ignition engines.A precis: "Bolt of Lightning Trigger"....a transistor switch used to carry the heavy current that the points normally do.The points now switch the transistors "base" to ground and the transistor switches the heavy coil current,causing the spark to be produced at the HT terminal.Points now switch a tiny current,there is no arcing at the points,point cleanliness and condition is far less critical".The coils we use are of course miniature aero specific type.Will try the capacitor and also experiment with a metal mesh screen to "fence off" the engine from radio.Thanks for your advice.

Specifically,we are trying to operate Ohlsson and Frog engines,all of 1940s vintage.Standard coil and contact breaker points,a gizmo from US in place of condenser(Larry Davies item) and seperate three cell battery.A micro switch in circuit,mechanically operated from a "throttle " servo,serves as kill switch.This exercise was to a degree,inspired,or at least accelerated, by an article in recent BMFA News by Andy Brough.It is likely to be of fairly short duration.These old engines have no silencers and even the small 23 and 29s are pretty noisy so it is the intention to only operate them at our isolated private site and vintage meetings where  they are accepted.Please enlarge re capacitor across points and what is meant by electrically isolated from RC.