Engine Doctor

Hi do fit a good filter clunk like a sintered metal clunk as the tins will rust with glow fuel and bits of debris will find their way to the jets. I think the uniflow will only work going up so that a tank can be placed lower and let the engine draw fuel from a sensible lift. When you lower the header tank the head of fuel will still be from the highest fuel level to the lowest outlet . Let us know how you get on .

Hello you got it right about the timing . The os 40 surpass could be a so and so for throwing props and were some times critical on fuel settings . I say sometimes as they seemed to vary a lot between engines . Set the main needle slightly rich and run the engine at full throttle slowly turning the main needle in until it will run without the glow connected, It should still be misfiring slightly with plenty of smoke. Continue to weaken the mixture until it runs cleanly . Listen to the exhaust note . If it sounds as if it starts labouring slightly with a hard sound then close the throttle slightly before it throws the prop then richen the mixture a few clicks and start again . Another trick is to fit a Taylor short reach idle bar plug if you can find one or put a second copper washer on the existing plug. In extreme cases a head shim will be needed as last resort . The shorter plug or second washer reduces the comp ratio slightly as will a head shim so retarding the timing . You may loose a few rpm but not enough to worry about and getting the last few rpm may mean the difference of a reliable engine or a prop thrower. Once you get it running ok at full throttle close the throttle slowly as they can throw a prop if you close the throttle and the bottom end mix is to rich. Once bottom and top end are adjusted correctly it should be a sweet engine .Whatever you do stay behind the prop out of harms way .

Posted by leccyflyer on 16/11/2014 09:58:39: Interesting piece in Nigel Hawes column about using the guts of an IC engine, with a shaft from a rear mounted out runner to provide the power. IIRC something similar had been proposed for vintage models allowing the appearance of those lovely classic diesel engines, with the reliability of a 21st century power train. Good stuff, Do they have a fuel vapouriser to give the diesel smell ? A diesel without the oil and smell of the fuel is like a pub with no beer . ps There was a guy at this years Nats Selling them . I believe he was from Belgium . Expensive though The Cox was 96 Euros . Edited By Engine Doctor on 16/11/2014 11:31:05

Re the rattle can acrylic. I sprayed a cowl for a build with a beautiful metalic green and finished it with two pack clear. It was fine for a while then the edge must have got rubbed and the fuel, Becra 20% crept under the clear dissolving the colour coat and bubblingand lifting the clear coat. Modern petrol contains a lot of ethyl alcohol which like methanol will dissolve acrylic paint. Do make sure what ever you use that the edges are well covered/coated . water based paint should be immune but do test first as Ronseal water based varnish is softened /dissolved by isopropyl alcohol . I found that out after spilling some on a window sill !

Hi Martin . You have answered your own question. You are correct in thinking that the head of fuel will still be too high an will syphon to the bottom tank and then into your engine. The carb extention would work best but,...........the one I posted was for a OS type engine and is a simple job to make . Lasers are a different animal and while its possible to make an extension it would be more challenging. Could you not mount your laser on its side with the carb uppermost ? This would surely sort most or your problem. The only other engine that would be fine without any mods would be a YS as they are designed to work with a tank pressure of 10 to 13 psi ,but they are expensive. Without seeing your installation it appears you are between a rock and a hard place and have limited choices if you wish to keep the laser installed inverted. The OS 70 is a well sorted engine ,why not use it?

I never had any bad problems with interference on 35 Meg since brushless motors bacame the norm. The old brushed motors were dreadful noise genorators even suppressed motors could down a model at range .Occasional problems occurred  when setting up petrol powered models . The added problems of the ignition system did occasionally cause concern. To cure this I fitted an opto isolator to isolate all the servos from the RX ; this together with PCM RX cured all problems. On smaller glow or electric powered models I used Schulz's RX's these were designed to be used in electric powered models and I never had a glithch with them. All the big manufacturers however were very hit and miss .Have now gone over to FrSky 2.4 with my Ff9 tx and never had any problems at all even when flying at extreme range. Edited By Engine Doctor on 16/11/2014 08:49:20 Edited By Engine Doctor on 16/11/2014 08:50:26 Edited By Engine Doctor on 16/11/2014 08:51:37

Yes have to agree Check .........check and check again even if its something that look solid like battery, servo, engine mounts etc give them a good tug and if in doubt re glue them . Last year I bought a large 30cc Chipmunk from a guy down hove way. He seemed an OK sort and assured me it had been flown and all was ok . He lied , glad I hadn't bought a car from him . It was a can of worms as one thing after another was found to be faulty during the check over and it could not possibly have been flown the way it was.After a few days I thought I had it sorted and went to our field to fly it . It took off beautifully climbed out then went haywire as if the battery had slipped to the tail .....it had! Then I found I couldn't close the throttle .I had fitted an ignition cut out so switched off the engine and managed to glide it to an area of standing corn that cushioned the arrival . Total disaster averted but could have been much worse. The COG had moved as the battery mount that looked securely screwed in was only screwed to 1/6th balsa with no glue and this must have let go on the take off run. Then the throttle servo problem . This had worked perfectly during run-ups etc but was now the gears were slipping ? As soon as I removed it from its mounting the fault was obvious . Two of the screws that hold the servo case together were missing and the other two were very loose . It had to have been fitted like that as the screws couldn't have come out in situ as there wasn't enough room . The servo all looked ok in the model and appeared firmly fitted. I put the above all down to me for not being more thorough. So DONT believe what anyone selling a model says unless you have seen it fly and you know them very well and still check it thoroughly. Edited By Engine Doctor on 14/11/2014 17:20:53

Favorite moment of 2014 for me was our clubs 40th Anniversary day In September. We had a great days fly-in with an evening BBQ and then night flying with a firework display .The fireworks that evening were really good . Watch them here and watch out for the lazy Bee Night flyer narrowly missing the quad copter filming the show .  A great day with great people . Lets look forward to the next 40  E.D. Edited By Engine Doctor on 13/11/2014 12:12:22

Use the bits that cymaz's link refers to.nearly all of the so called silencers sold don't silence but merely direct the sound. The inserts do quieten the exhaust quite a bit. I have made some and fitted them to a Dle 30 and a Rcgf 15cc they work OK with only a small Loo's of power.

You could ask her for a lift to the flying field occasionally

Hi type carb extension into the search panel for a previous thread. I fitted this mod to an sc 52 some years ago and it worked brilliantly. The engine in the. Pics is a saito and is just used as a demo. The model was a proto type corsair with a glass fuz that had had a tank platform fitted at the upper half of the fuz . the engine was fitted inverted so as to hide the head from sicking out of the top. This mod raises the carb to the height you want and stops all the flooding issues.

Hi I built one of these for a club mate a few years back. And have since built/finished and modified a Pica Mustang. The main criticism of the kit isthe wood quality .The balsa was hard and heavy and the ply parts were made of the poorest quality light ply imaginable. I replaced and re cut a lot of the parts . I still have a instruction manual to it. Another point to consider is the twist and turn retracts required .These need to fit around the lower wing spar and I believe Robert were the only ones available at the time . The owner refused to buy Roberts and I refused to bodge his wing to take the set of retracts he had .He took the wing and fitted his non standard units and cut the lower spar out to make them fit . The area of wing was strengthened with carbon fibre tows and epoxy that bridgedcthe area. As far as I know the model is still flying in a well known warbird team. The general build is quite straight forward but if you wish to fit a radial mounted engine then the front end will require a lot of modification as its designed around the engine bearers.

Hi Craig . Models designed for glow IC generally have the tank fitted behind the firewall as glow engines dont usually have a pump fitted and have to use exhaust pressure to help get the fuel to the carb so a short run is beneficial . As petrol engines exhaust is much hotter using exhaust pressure is not a good idea . All modern petrol engines and some of the more expensive/exotic glow engines have pumped carbs enabling you to put the fuel tank where ever you want ,within reason . If its possible why not fit it on the CoG that way the flying trim wont change as fuel is used . This is the norm on F3a and highly aerobatic models . Re the tanks . I have made my last few tanks from 1/2 liter fuel bottles as supplied by Southern model Craft . these give a good 10 to 15 min on a 30 cc so a 35cc should not be too different.The fittings are slec fittings and for a clunk I use the sintered metal clunk filter made by Du-bros or Ripmax . Felt filters are also used but they do tend to have very thick tube attachments as they are generally industrial filters used in chainsaws etc. If you buy a tank DO make sure it has a gas bung as already said . If you dont it will soon start leaking . Dont forget the tank needs to be vented ( unlike a glow tank ) so that air can get in to allow the fuel to be pumped out . If you dont vent it your engine will eventually stop and the tank will be crushed flat by atmospheric pressure . Re the throttle servo . You can fit that wherever there is room whit a conventional snake or on the firewall with a short push-rod whatever suits your application. Try to work out what will give you the best balance . Dont use minature servos on the throttle as petrol engines and large glows inevitably vibrate more than their smaller counterparts . Use a decent quality servo , doesn't have to be digital or anything fancy but something that has gears etc that can take the vibes.

Hi try to run the choke cable out of the bottom of cowl as suggested . If its really inconvenient and has to come out of the front don't worry. Just make sure that when its pulled out it doesn't hit the prop. When using the choke the motor will pop a couple of times then stop . Now you push it in (take the choke off) and re start engine so no loss of fingers To help draw fuel through on the first start of the day I have found it helps if the small air bleed hole in the choke bútterfly is soldered up . Choke works much better with this mod.

I assume you have balanced all the usual suspects ,prop and spinner ?I fitted a Saito 82B into an acrowot that I was asked to build for a club mate. I was asked to get it flying an did the test flight .It proved to be very powerful and smooth. Only criticism was the oil from the exhaust but that's was obviously down to the fuel used,bekra I think. We later changed to southern model craft 20% with 17% synthetic oil which was much better. You may have a badly balanced engine as they do occasionally escape the factory. I have two supposedly identical YS 140 FZ's one is so smoooooth and the other one vibrates into a blur? So bad in fact that I won't use it until I have stripped and checked why (it was unfortunately out of warranty before I used it and found the problem) .Do let us know if you cure the problem.

That's correct the black plastic spacer is the insulator block .If it stuck to the carb that's fine and all the air passages should line up fine.

Do leave the spring on and connected . As already said should the linkage fail then it a fail safe to idle or engine stop . If its removed or disconnected then the butterfly can vibrate causing the spindle to wear in turn causing air air leaks and poor idle . Never had any problems with servos handling the spring pressure either ,just use a decent servo and not mini servo as the vibes will kill the gears in no time . The old 148 or similar are fine for this and hold well without scoffing all the battery power. Re turning the carb 180 deg . Usually not a problem but do make sure any holes in the insulator or gasket line up you will also have to turn the insulator block as well . Some engines use drillings to allow crankcase pressure to work the diaphragm pump while others have a short length of tubing from a crankcase nipple to the carb . I regularly change mine round without any problems .

A bit like buses none for ages then they all come along at once ! An up-date to the above message . The Date for the January indoor meet has had to be changed due to clash of bookings at Medway Park . The new date is now the 4th of January . As before go to www.medwaymfc.org.uk for further details .Thanks

Anyone wishing to attend Medway MFC's indoor flying meetings in November and December please note that the venue is Medway Park (formerly Black Lion sport centre) not fort pit as advertised. For more info go to : www.medwaymfc.org.uk

Remember this Mantra " Aim at the ground and miss grass hopper" and all you flying will be fine . It also helps repeating the said Mantra when picking up all of the wreckage . Have fun practicing and whatever method you choose if its legal, safe and works for you then its fine . Edited By Engine Doctor on 25/10/2014 10:35:32

Hello .Turning your back slightly or pointing your Tx the same way as the model is travelling is fine . I often suggest that method to students when Im teaching as an aid until it all comes naturally. If it works for you then its fine

Not so bad news now ! It looks like common sense prevailed. An article in the Basingstoke Gazette says that the local council gave the club a modified Cert of lawful use with slightly modified flying times . The articles says the new flying times start at 10 am and finish at 7pm or dusk. Well done to the club committee for standing up to busy bodies who think they are more important than anyone else. I hope the busy body had a very big bill for wasting everyone's time. Edited By Engine Doctor on 19/10/2014 10:13:51

Hi try Woodfill by Ronseal. Its a two part filler similar to car filler but a lot lighter. You can get it in white or biege . it sands well and at a similar rate to balsa so no ridges. More expensive than the wicked lightweight filler but more durable and quicker.

Thanks for responses . ED

As per title what makes of Tx can be used as a buddy tx with the Tarnis ?