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BCMIEV20RC - BCM 5619

BCMIEV20RC - BCM 5619

75.58

BCM Inverted muffler for the Evolution 20cc petrol engine with a cut away for round cowl. Dimensions: A=90mm D=64mm L=115mm W=30mm. The exhaust flange is 12mm thick.
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BCMWADL55 - BCM 10514

BCMWADL55 - BCM 10514

144.00

Wrap Around Inverted muffler for DLE55 with extra noise reduction. Dimensions A=3mm, B=76mm, C=25mm D=50mm. The exhaust flange is 10mm thick.
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BCMIDL35 - BCM 10506

BCMIDL35 - BCM 10506

78.60

BCM Inverted muffler for the DL35 rear exhaust. Dimensions A=76mm B=51 C=115mm. The exhaust flange is 10mm thick.
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BCMIOSGT33 - BCM 4034

BCMIOSGT33 - BCM 4034

75.58

BCM Inverted muffler for the OS GT33cc petrol engine. Dimensions A=76mm D=82mm L=102mm W=32mm. The exhaust flange is 32mm thick.
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Zenoah G800BPU 80cc Flat Twin Aero Engine

Zenoah G800BPU  80cc Flat Twin Aero Engine

599.00

!!<Specification:

Cylinder displacement: 79.9 cm / 4.88 cu.inch
Cylinder bore: 40.5 mm / 1.59 inch
Cylinder stroke: 31 mm / 1.22 inch
Power output: 4.34 kW
Carburettor: ...
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Zenoah G62PU 62cc Aero Engine

Zenoah G62PU  62cc Aero Engine

310.00

!!<Specification:

Cylinder displacement: 62 cm / 3.78 cu.inch
Cylinder bore: 47.5 mm / 1.87 inch
Cylinder stroke: 35 mm / 1.38 inch
Power output: 3.15 kW
Carburettor: ...
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G450PU 45cc Aero Engine

G450PU 45cc Aero Engine

299.00

45cc Side exhaust petrol Engine with Zenoah Magneto ignition as standard !!<Specification:

Cylinder displacement: 45 cm / 2.75 cu.inch
Cylinder bore: 43 mm / ...
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Zenoah G380PU 38cc Rear Exhaust Aero Engine

Zenoah G380PU  38cc Rear Exhaust Aero Engine

238.00

38cc rear exhaust engine with magneto ignition as standard !!<Specification:

Cylinder displacement: 37.4 cm / 2.28 cu.inch
Cylinder bore: 38 ...
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Zenoah G260PU 26cc Aero engine

Zenoah G260PU  26cc Aero engine

244.00

!!<Specification:

Cylinder displacement: 25.4 cm / 1.55 cu.inch
Cylinder bore: 34 mm / 1.34 inch
Cylinder stroke: 28 mm / 1.1 inch
Power output: 1.62 ...
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1/8 Robart "T" couplers (pack of four)

6.50

For joining fuel tube good for glow or petrol. !!<Glow OnlyPetrol Only Suitable for Glow fuel ...
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3/32 Robart "T" couplers (pack of four)

3/32 Robart

6.50

For joining fuel tube good for glow or petrol. !!<Glow OnlyPetrol Only Suitable ...
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Multi cylinder glow start

Multi cylinder glow start

156.00

The perfect solution for starting your multi cylinder glow engine without the need for an on-board glow system or a massive battery pack. It is powered by ...
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Three Cylinder Glow Driver

Three Cylinder Glow Driver

60.00

The compact unit operates 3 glow plugs independently using a single cell LiPo or 3 cell NimH battery. The switch-on point is programmable and the unit will automatically turn the plug ...
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Electric smoke pump

Electric smoke pump

46.50

A powerful self priming pump that plugs straight into a switched channel on your receiver. No need for an external power supply. The diaphragm pump works ...
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X-OS25830010 OS Engine Crankshaft Bearing(R)50H/55AX/55HZ

22.99

OS Engine Crankshaft Bearing(R)50H/55AX/55HZ
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Radio Control Model Flyer July 10

Just Engines Online | Ignition Systems | Magazine Articles and Reviews of our Ignition Systems |  Radio Control Model Flyer July 10

Page 1

Page 1

Regular readers of RC Model Flyer will possibly already know of my exploits with electric powered model aeroplanes, which I report upon every month in my Black Art column, but before I became involved with this quieter method of powering my models, I flew for many years using a variety of IC engines, most of which I still have stored away, swaddled in oily rags end sitting in boxes on my workshop shelves, ready for those times when I sufficiently miss the noise of an IC engine. One thing I definitely do not miss, however, is the 'washing down' of the models after a flying session and this was brought home to me recently when I assisted my good mate Richard Cox with his glow-powered Hangar 9 Pulse XT12S, reviewed a couple of months ago. Knowing Richard needed some decent in-flight shots, I actually had to wipe all the goo from the canopy area with a rag, with the engine still running ready for the first flight, such was the quantity of castor oil being thrown out of the exhaust, and it was at that moment that I realised my previously made decision to convert as many of my glow models to petrol power was a timely one. The state of my coat, covered in similar quantities of greasy, slimey 'goo' was also a deciding factor, as was the nauseating smell of burnt castor that we endured all the way home in the car.

Petrol concerts
Petrol-powered model aeroplane engines are nothing new, and have been around for a long time, however, of late it has been possible to buy stand-alone electronic ignition (CDI) modules and all manner of accessories to convert many two and four-stroke glow engines to petrol-fuelled (okay, gas if you live on the other side of the Atlantic) spark ignition operation, and it is one of these units (from Just Engines, £45 each)) and their fitting to a variety of engines that I am going to describe in this article.

So how does it all work...
At its simplest, all we need to know is that the ignition control unit as supplied converts the input voltage (typically 4.8v - 6v) provided by an on-board battery, to a voltage of around 14,000v and this is enough to cause the high voltage electricity generated within, to jump the gap in the spark plug, and in doing so, ignites the fuel/air mixture in the cylinder. Obviously, sparks going off in the cylinder at random intervals would not work, so the timing of the sparks needs to be co-ordinated so that they ignite the fuel/air mixture each time the piston just about reaches the top of the cylinder (Top Dead Centre or TDC), and we will refer to this later. To synchronise the firing of the spark with the correct position of the piston, the electronics package needs to know where the piston is, and it does this by using a small magnet set into the flywheel to trigger a sensor as the engine turns over. Naturally, we will need to know that if the prop driver is removed for any reason, we can ensure it goes back onto the crankshaft in exactly the same position. The easiest way to maintain this relationship is to scribe a line across the prop driver/flywheel and the front of the crankcase, with the piston in a fixed position, TDC being as good as any. If you subsequently remove the flywheel/prop driver for any reason, simply set the engine at TDC, line up the scribed lines and the relationship between the angle of rotation of the flywheel/prop driver and piston is restored. Some engines use a Woodruff key to locate the flywheel/prop driver to the crankshaft, rendering this as unnecessary - however, you may not know this until you pull them apart, so I would still scribe a line even if you suspect a key is used, because it's a bit late to find out it doesn't, once they are pulled apart.

Page 2

Page 2

Goodbye warranty
The first thing to remember is that this is a conversion, so you are going to need some degree of engineering/modeling ability, exactly how much being dependent upon the type of engine you are converting, and how tidy and professional you want the finished item to look on completion. One thing you can be sure of is that carrying out any modifications will no doubt see your engine warranty disappear faster than a cat after a rat, so if you are not prepared to accept such a scenario, the answer is to simply decide to not convert your engine.

Magnet and sensor

Fitting the electronics unit is straightforward - you simply follow the manufacturers instructions. Like-wise, retro-fitting the fuel tank and engine plumbing with petrol resistant fuel tubing (not forgetting the short length inside going to the clunk) as well as the rubber bung in the front of the tank if one is fitted, is not going to stretch the average modellers abilities, nor is the fitting of the spark plug in lieu of the glow plug, however, it is when you come to fitting the sensor that most user discretion and ingenuity should be exercised. Before we begin to fit the sensor and magnet however, we need to get our head around one important fact - the electronic unit takes a finite amount of time to process the signal (generated by the magnet passing over the sensor) into a spark, and also the ignition of the fuel is not instantaneous, and because of this we have to take into consideration all of the following and set up the magnet and sensor so that they pass each other and trigger the ignition cycle some twenty eight (28) degrees before TDC, which in practice is very easy to achieve. The simplest way of achieving this is to temporarily fix the sensor to the engine crankcase and mark where it is going to finally sit, then fit a protractor to the crankshaft. A cheap plastic protractor is fine for this job, but you will have to drill a hole in it to clear the prop shaft. Just Engines do sell a rather more elegant device, which may be a useful investment if you decide to convert a few engines. With your protractor in place, set the piston at TDC, and then scribe a mark on the flywheel/prop driver some 28 degrees away from (and in advance of) the sensor centre line, such that when everything is fitted in place, you will need to wind the engine back twenty eight degrees for the magnet and sensor to line up. The flywheel is then removed, drilled for the fitting of the magnet and with the magnet pushed into place, the flywheel is re-fitted, (hence my earlier comments about ensuring it goes back in exactly the same place as it came off). Please note that for the system to work, the sensor must 'see' the correct end of the magnet. Magnets by the very nature are polarised so do ensure that you fit the magnet with the correct alignment full details of this being given in the instructions. Enough of the theory, lets look at the practicalities...

Page 3

Page 3

Different approaches...
The simplest installation is to use the supplied sensor mount, a dab of high modulus silicone and a cable tie to fix the sensor in place, and indeed this method can be very useful in setting up the engine. I am assured that this is the method chosen by many converters and although rather crude in appearance, it works well, but there are other ways of mounting the sensor in place. One method I used on the conversion of my ASP 120 FS, was to find a hose clamp (Jubilee clip) of suitable diameter, and soft solder to this a short length of brass channel section. The sensor was securely fixed into the channel using some epoxy, and once set the whole item was fixed onto the front bearing housing simply by nipping up the clamp, just as you would when fitting to a hosepipe. This is a rather neat solution as it is very solid, allows for some final adjustment if your measuring with the protractor was not as accurate as you would have liked, and has minimal impact on the appearance of the engine. Indeed, if you wanted to convert back to glow power at any time (although I don't know why anyone would), the engine would look virtually unchanged, apart from the unobtrusive magnet in the flywheel. Another method is to drill and tap a couple of holes into the front bearing housing allowing the fitting of one of the two supplied sensor housings, however, this necessitates at the very least, the removal of the front bearing. This is something that many modelers may not be happy doing, so only consider this if you know your actual engineering skills measure up with your ideas and aspirations.
An equally satisfactory and elegant method, and one devised by the aforementioned Just Engines Geoff, is to turn up an aluminium ring that can be slipped over the front bearing housing, and use this to locate the magnet sensor. Geoff is a bit of a dab hand at welding aluminium, so chose to weld a small alloy tube into the ring that he machined that the sensor is held in place in the tube using a dab of silicone sealant whilst the ring is held in place either by being a 'perfect fit' or by provision of a couple of grub screws to nip it into place. By perfect fit, I mean the ring is machined so that by heating it up, it expands sufficiently to enable it to be slid into place over the front bearing housing, whereupon it cools and contracts for a very solid and professional looking conversion - but this does not allow for any kind of fine-tuning of the sensor position at a later date.

Advance and retard...
Mention is made above of 'fine- tuning' the relationship between the sensor and the magnet used to trigger the ignition cycle, so this may be a good opportunity to mention the whole subject of advancing and retarding the timing of the spark. Anyone who has seen an old film on television, where a motor car is started by hand using a starting handle sticking out the front underneath the radiator, may have noticed that the person about to start it moves a lever on the centre of the steering wheel before cranking the engine. This system mechanically alters the ignition timing, so that at start up, the spark is retarded (fires a little later) to assist starting and prevent the engine kicking-back or back-firing, then, once the engine is running, the lever is placed in the normal position and may even be advanced further at high revs to extract as much power as possible, and ensure smooth-running. The amount of advance and retard for optimal performance alters continuously with the speed of the engine, and this is where the CDI units come into their own, because this is all handled for us automatically by their clever electronics. The only set up adjustment needed with them is to accurately set the 28 degrees advance.

Battery needs

You will need to provide a suitable sized battery pack to power the ignition module, and for obvious reasons, the instructions supplied with the electronic ignition module advise you not to use the pack that you use to power the onboard RC system. A 4.8v 4-cell receiver pack is perfectly adequate, and one of around l200mAh capacity will be enough for a whole weekend of flying. The supplied instructions give ample details with regard to battery choice, and warn against using too high a voltage as this will damage the unit, so do not be tempted to use a 25 lipo pack. That said, I have found that a stand alone BEC unit, as used by electric flight enthusiasts, set to 4.8v and coupled to a 2 or 3S lipo pack works fine, the only danger being that if the unit fails, the power supply may cease, causing the engine to stop, or it may allow the unit to 'see' the full voltage of the pack, and damage the CDI unit in the process, so unless you are 'au fait' with SEC and LiPo technology, etc, it may be best to stick with a four NiCad or NiMh pack.

Petrol mixture...
To ensure adequate lubrication of the engine internals, it is essential to mix some oil in with the petrol that we are going to use to fly our model. Petrol has intrinsic lubrication properties unlike the Methanol we use in our glow fuel, and we can use this property to reduce the oil content of our fuel dramatically (and therefore the amount spewed out onto our models), compared with glow fuel. The exact percentage of oil required varies upon the quality of oil being used and the type of engine being converted, and again, Just Engines will be able to advise you regarding this. Suffice to say, follow their advice to the letter, because as with any engine, whether they be petrol, glow, diesel or even gas-turbine, using the wrong oil or insufficient quantities of even good quality oil will cause premature wear and damage to your engine. That said, the percentage of oil used in our petrol/oil (petrol) mixture is significantly (many fold) less than in glow fuel, so do not be tempted to 'add a little bit extra' just to be on the safe side.

Page 4

Page 4

Safety first
Petrol is very inflammable. It is arguably much easier to ignite than methanol (especially when the methanol is mixed with considerable quantities of oil as in our glow fuels), therefore, always keep your petrol mixture in a suitable container, and exercise due caution when fuelling up your model or storing your fuel. It goes without saying that you should not smoke in the area where a petrol model is being fuelled up or operated, but then I guess that goes for any type of IC engine. One thing you must be aware of is that once the ignition is switched on, the engine is liable to start if the prop is turned or knocked. Indeed, depending upon the position of the propeller and the amount of residual petrol vapour in the cylinder, it is feasible that simply switching on the ignition could cause the engine to burst into life. One of the first things you are taught when learning to fly full-size is that you should assume that the engine is always live and ready to start, and you are advised therefore to never swing the prop, or even slowly turn over the engine by hand, unless you are sure the magnetos are shorted, unless you mean the engine to start.

Engine kil switch

A standard switch between the CDI unit and the battery is sufficient to stop the motor after a flight but mention should be made of an engine kill-switch that is also available from Just Engines. Priced at just £ 14.99, this device allows you to kill the engine at the flick of a switch on your transmitter and therefore by using the failsafe facility on your radio system (or a stand alone failsafe unit), it could be configured so that the engine stops if the radio signal (or receiver battery power) is lost for whatever reason. Petrol engines are much more fuel frugal than their glow-powered equivalents, and the last thing anyone would want is for a large model (with fuel on board for nearly an hours running), to fly-away, especially as the now ultra-reliable engine is likely to keep going until the fuel runs out or the model hits something. As nell as the kill-switch, Just Engines supply other additional bits and pieces for simplifying the conversion process of your engine to petrol spark-ignition power, and once you are a convert I doubt you will ever want to revert to glow fuel. These additional items include a tachometer and an ignition test kit and these, whilst not essential, certainly enhance the whole petrol experience. Just Engines have been selling these CDI units for a good while now, and have numerous customers who have carried out conversions on a great variety of engines with great success, and they are more than happy to advise you how to proceed if you want to go down this route.

Austerity action

I hate to propagate further doom and gloom about the economy, especially as we all fly our models for the great pleasure they give us and having worked hard all week, there are few better ways to spend a Sunday morning! However, as one flyer recently commented, he can get through two gallons of 30 per percent glow fuel in a weekend, which at nearly £30 per gallon, which makes a petrol conversion very financially viable, even with petrol fast approaching f6 a gallon. Add to this the fact that reliability improves, fuel consumption decreases (making for smaller tanks or longer flights), starting is much easier (not least because you need less paraphernalia), and last but definitely not least, the model is far cleaner at the end of a flying session, requiring minimal or zero cleaning up, and suddenly the merits of petrol power simply cannot be ignored.

Other useful items for glow conversions

As weil as being suitable for converting methano].-burning glow motors to petrol-powered spark ignition, the conversion kits are also eminently suitable for repairing damaged engines that have this, or a similar, system factory fitted and which has subsequently been damaged, hence the lack of a spark plug and magnet in the basic kit. I have therefore outlined at the end of this article the optional extras that are available, and have grouped them into three groups, these being entitled 'essential' (for a conversion as opposed to a repair), 'advisable' which equates to 'having these items will make the conversion and subsequent setting up and running that much easier, and 'desirable' this being the 'icing on the cake'.

Essential
As weil as being suitable for converting methano].-burning glow motors to petrol-powered spark ignition, the conversion kits are also eminently suitable for repairing damaged engines that have this, or a similar, system factory fitted and which has subsequently been damaged, hence the lack of a spark plug and magnet in the basic kit. I have therefore outlined at the end of this article the optional extras that are available, and have grouped them into three groups, these being entitled 'essential' (for a conversion as opposed to a repair), 'advisable' which equates to 'having these items will make the conversion and subsequent setting up and running that much easier, and 'desirable' this being the 'icing on the cake'.

Advisable
2 Whilst the CDI ignition system will happily operate the engine without the fitting of the Opto Gas Engine Kill Switch (114.99), the problem is that should the radio fail, it will keep on working. I would therefore suggest that this is an essential extra, especially on larger or heavier models, and an advisable! desirable option on all models, irrespective of their size. Easily fitted into a spare RC channel, the unit is opto isolated to minimise any chance of interference to the RC system, and is fitted with an LED that can be located on an appropriate part of the model to indicate when the system is live, which in itself is a very useful safety feature.

3 The 'Ignition Hall sensor test kit' (11 1.23) is very useful, and consists of an electronic module and a 360 degree protractor with a pointer that can be set at the magical 28 degrees. This must be drilled out to fit over your crankshaft, and is used to set the correct static timing of your engine, as well as for checking the correct operation of the hall effect sensor, as well as the associated magnet. You will need to order a pair of CR2032 batteries to operate this unit as they are not included. To check your setup, simply conned the engine- mounted sensor to the electronics module and fit the batteries, then slowly turn the engine over. At first, the unit appears to be doing nothing whatsoever, until that is, the point is reached where the magnet triggers the sensor, at which point the buzzer will sound and the LED will glow simultaneously.

4 To check the rest of the system, an ignition test kit (17.99) is available. This emulates the output of the sensor and magnet combination, and allows the ignition system to operate just as it would when the engine is running, and can be set anywhere between 400 and 20,000 rpm. This allows you to check the operation of the ignition system, and is also useful for carrying out a preliminary range check of the RC system, however a final check should always be carried out with the engine actually running.

5 The digital Tachometer (114.99) allows the ability to accurately monitor the RPM. The mini tachometer comes complete with a suitable Y-Lead to connect it into the ignition unit wiring loom, and like all the other units, a set of operating instruction, which I would have to describe as 'adequate' rather than 'brilliant', although all becomes clear if you re-read them through a few times.

Just Engines Online | Ignition Systems | Magazine Articles and Reviews of our Ignition Systems |  Radio Control Model Flyer July 10