The RCGF engine company is well established with a good range of single and twin cylinder engines ranging from, at this stage, 10 cc to 60 cc, a selection providing the power for a majority of aircraft sizes. I have had several years of experience with these engines having examined one in the very early days at my float fly club. A member had obtained one and bought it to my attention as a point of interest. I was quite impressed with the external quality and then, later, with the performance of the engine in the model over several flights on the day. The occasional one cropped up here and there and I heard only good words from the owners which was interesting, as I am sure we all know how critical some modellers can be. Later on, Mario Agius, a well established modeller, had some experience with them, saw a niche and obtained the Australian agency.
ENGINE: RCGF 10CC
CONFIGURATION: Single two stroke, petrol, spark ignition
DISPLACEMENT: 10 cc
BORE: 27.6 mm
STROKE: 17 mm
WEIGHT: 570 g ready to run
STATED POWER: 1.4 kW
R.P.M. RANGE: 1,800 – 12,000
PROPí RANGE: 13 x 6 – 14 x 6
FUEL: 25 to 40:1 90 to 95 RON petrol
SHAFT THREAD: UNF 1/4 x 28
SUPPLIED WITH: All running equipment, instructions, decals, engine mount complete, special screwdriver.
DISTRIBUTED BY: RCGF ENGINES AUSTRALIA
www.rcgfenginesaust.com or contact Mario on 0417 123 426
The rest is history as Mario looks after the product and his sales are encouraging enough for him to maintain the product rights. My first close up and personal experience was with the 15cc single and that really impressed me. I could not fault the engine and, talking to Mario, said that I would really like to get some first hand experience with a small twin. Apparently the manufacturer was pleased with my review of the 15 so it was agreed that I should test and review a twin – the very nice 40cc version. With the previous tests being quite interesting and gratifying, it got my full attention when Mario rang me to say he had the latest 10 cc engine on its way for testing and review. Engines of this capacity were the ëbigí engines in early days of RC but, these days there are so many monster engines and super large aircraft on show, some modellers forget the enjoyment of a nice 10cc model that will most often comfortably fit in the car, is low cost all around and not so nerve-racking to fly as you donít have your childrenís education fees invested in the model. Don’t get me wrong – I like all engines regardless of capacity and all model sizes. For sure, the larger models are easier to see if youíre nudging the calendar a bit, but a 10cc engine will power a wide range of aircraft right up to larger sizes if you understand wing loading. On the other hand, how about some reasonably large multi engine aircraft? Using 2 or 4 (6? 8?) 10cc engines is not going to require a half scale monster plus, the dreaded ëengine outí syndrome is way down on the list with a spark ignition engine and, again with a ësparkyí, the engine idle is super low and reliable. Lots to be said for this size and type of engine and donít forget, as it uses petrol fuel, you can fly ëtill the TX battery is flat and the fuel cost will be lower than a beer at the local pub.
EXAMINATION & OBSERVATIONS.
Casting a critical eye or two over the engine, both inside and out, I compiled the following notes.
The crankshaft appears to be forged steel and it is quite tough. It is supported by sealed bearings both front and back so lubrication is not a consideration here as the bearings are sealed for life. As well, in the case of a bearing failure (simple fact of life), no metal bits or shards are let loose to play havoc with the internal parts of the engine.
I spent a considerable time examining the connecting rod as it sort of fascinated me. In the majority of large petrol engines – particularly those that have common parts, the connecting rod is forged steel copper coated on the shank and hardened in the areas of the big and little end eyes. Now, to explain first the ëcommon partsí. A manufacturer of petrol type model engines might start right back on the drawing board (or CAD screen on the computer more likely) to design an engine. Consideration at all times is the cost in a highly competitive market, so donít reinvent the wheel. There are established manufacturers who specialise in connecting rods, pistons and piston rings and these parts are well established in the engine market, be they for model use or hand tools. Logic would indicate that the incorporation of these tried and test components would be used in your newly designed engine and that is why the rods and the pistons seem familiar in many petrol engines – most come from the main supplier.
Now, concentrating on the connecting rod specifically, the forging process – simply, a lump of steel is heated and then hammered to the shape required – a very simple description of the process. This produces a very tough item as the metal flow is directed throughout the shape of the forging allowing for very small dimensions to be used without weakening the finished job. This is evident in the shank of a typical forged rod slim as a female fashion model. NowÖif that super slim rod was hardened by heat treatment, the slim sections would become brittle butÖas a needle roller is to be used both ends, the hardness is required in those two areas. As the heat treatment process used works only on steel and not, for example, on copper, and it is extremely easy to apply a quick coat of copper to steel, the answer is to copper coat the sections not required to be hardened so you end up with a super tough shank and hardened eyes on the ends. Now, considering all that information, you can now see why the connecting rod in this ësmallí engine was of interest to me – it is forged steel with needle roller bearings both ends and this alone is the reason why the engine is quite safely run on 40:1 fuel – a very low oil content mix.
Moving on a bit, the piston is cast aluminium alloy and a simple scratch test indicated that it is quite a tough customer. It is fitted with one cast iron ring (most commonly used metal for rings) and slides in the internally hard chromed cylinder – the chrome plating applied direct to the aluminium alloy wall. You won’t wear his one out in a hurry. While I was examining parts in this area, I noticed the asymmetric shape of the back cover – the bolt pattern allows for one position fitting only. The purpose of this is that, being a small engine, there is not a lot of free room on hand so all parts have a place and must remain in that place. To fit the back cover in any of the other three positions would have the piston or connecting rod ëinterferingí with the reed valve assembly with disastrous results.
On the front end of the crankshaft, the well knurled propeller drive hub is keyed to the shaft – Woodruff key (D shape) which is necessary to retain the magnet position for timing. Plenty of shaft length for thick hub propellers and the addition of a spinner backplate if used. Thread is UNF 1/4 x 28 – common for many engines around this size and many spinner adaptors and spinner nuts are available with this thread.
The muffler is a very well made and neat little item but is has a rather healthy bark to it – maybe not suitable for noise sensitive fields but quietening it down is easy with an extension on the outlet for example. You can also fit a header and long can muffler if you wish as I did on the test bench (see YouTube.com/user/BrianOilyEngines).
ENGAGE THOUGHT PROCESS BEFORE OPENING MOUTH.
I had the engine at a club field for show and tell and it gained quite a lot of interest and several questions from interested modellers. However, as is said, one in every crowd – one loudmouth remarked, Yeah, all good if you say so but they were too lousy to drill the mounts for the engine.î A couple of the other modellers made a comment to him which propriety prohibits me from repeating but I gave him his answer as well as the information for those who were really interested.
Yes, I noticed that as well when I was admiring the very sturdy, well made supplied engine mounts that came with all mounting hardware required. I thought to myself, what a good idea to leave the mount sections undrilled. At 75 mm long on the beams, you have quite a good amount of position adjustment to suit the cowl length of your model which is much easier than having to add packers or, at worst, modify the firewall position. The mounting hardware includes socket head screws for the engine and firewall mount and nuts incorporating a washer section with a knurled face to provide grip against loosening by vibration. All the items are (nickel?) plated.
To tidy up my observations, the muffler can be mounted pointing up or down, and being a petrol engine it runs perfectly inverted.
Read the instructions regarding the ignition hook up but note that the CDI is a Version 2í which allows for a higher input voltage. While we are here, first time I have seen it – the plug cap is of the push on with the circlip closure style – seen on larger plugs commonly but the first I have seen on a 1/4 inch plug. It goes on well, is very secure and needs a little levering’ to remove it. Good idea.
The carburettor is absolutely unique, but as yet nothing about it has been added to the common (all engines) instruction manual. I have not seen its like in any engine before but I certainly do like it. It is a rotor type carburettor, revolving drum as is common in many carburettors, but no needle valves! Well, really there is one but not as we know it. In the underside of the carburetor body there is a brass insert that is screwed into position as it has an access slot for a screwdriver. This is not adjustable so don’t try it. Deep inside this insert there is an adjustable needle with a small slotted head. This is the main needle and here we have use for the supplied screwdriver. As I say so often, think a lot before adjusting as this needle comes well adjusted from the factory for initial running. It was only after I had a bit of running time on the clock I found the need to lean the mixture slightly for maximum RPM. There is no idle adjustment but the design of the carburettor is such that the idle is built in, so to speak, and it is very reliable. That’s one way of slapping the fingers of habitual needle twiddlers.
The pump for the carburettor is a small, almost flat item that you can install on the firewall, for instance, with the screws supplied and the sprung bracket. Pressure comes from the engine and the tubing is supplied. I was quite pleased with this fuel management system and found it to be extremely easy to use and very reliable. The pump has excellent fuel draw and no run back when the engine is stopped. No choke is provided but the engine winds up the fuel rapidly when the propeller is spun up or, as most modellers do or know, a finger over the intake for the first start works wonders.
ON THE BENCH.
I completed the testing on the 24.3.2015 with the temperature at 25 degrees C and humidity at 80%. I use a fuel mix of 32:1 with Morgans Blue Coolpower oil and 95 RON petrol. I chose the fuel ratio as I had several litres of it already mixed. For actual engine use, I would go to 40:1.
This engine is not a hand start job unless you are a well established flicker. It is very low on compression so the propeller bounce is absent. I found, after a bit of running, I could hand start it okay and the procedure was to prime it 3 times (finger prime), flick 3 times, switch on, turn the prop and, if you feel a bump, a flick will get it going. If you don’t get the bump in three turns, prime it once again. If you want to simply start the engine to use it, one tap with the starter has it off and singing in the blink of an eye.
I found it very smooth on both idle and maximum RPM with the harmonic (bit of a shake) around 3 to 4000 RPM. The low compression effect is evident when you notice the lack of general vibration and how flexible the engine is to run such a wide range of propellers. Just for interest (and my own pleasure) I ran propellers from and 11 x 7 to a 15 x 4 which is spreading the usable propeller potential over a very wide range and as you will note, no dramatic drop in RPM.
The engine was clean all over after all the test running; it runs for ages on a mere sniff of fuel and the operating heat was quite normal for a petrol engine.
My final note is, fun machine – nice acquisition.í
APC propellers used.
11 x 7 10,611
13 x 4 10,500
13 x 6 9,790
13 x 7 8,710
13 x 8 8,407
14 x 4 8,420
14 x 6 8,200 1,500 Idle
15 x 4 7,609