A.S.P. 'Series 3' 1.80fs - AMI

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by Steve Dorling

by Steve Dorling

Aviation Modeller International

There can be little doubt left in anyone’s mind today, that those clever Chinese are producing model engines that are as good as any in the world and in some cases better.

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When ASP pulled a rabbit out of a hat and produced their first of an up and coming range of four strokes around a decade back, these were clearly OS clones and nowhere near as well produced as the Japanese originals. Despite misgivings from doubters and soothsayers, who remained adamant that they would never go for an inferior product based upon a few quid difference in price, (and I had sympathy with them at the time) with the arrival of this new ASP 180 four-stroke, the goalposts have changed, because the Japanese didn’t produce a 30cc version of this design. ASP must therefore now be recognised as premier engine designers and producers in their own right and should you that think scaling up (or down) an existing design is an entirely straightforward affair, be assured that as often as not all sorts of problems crop up. Without going too deeply into the why’s and how’s, the surface areas and rubbing speeds change dramatically with dimensional variations which can impinge upon lubrication and mechanical stresses out of all relationship to the behaviour of similar devices at other sizes.

So – assuming that ASP have done all the sums and successfully completed a rigorous testing and proving programme, here we are with a very nice 30cc four stroke glow for that big scale or aerobatic mount and at a most acceptable price too! Any 30cc engine is going to be powerful and by definition it must be treated with the utmost respect, given that you are going to bolt a blade to the business end of things, the size of which would grace a small lawnmower. You most certainly wouldn’t put a digit within striking range of the blades of your mower without thinking very hard about it first, so do take care when handling these bigger engines. My advice is to handle something of this stature as though it was an industrial cutting device and you are part way there to minimising the risks and the risks with a 180 four stroke are in the absolute certainty of the loss of flesh and bone if you do get bitten – i.e. you don’t get a minor cut from a foot and a half of propeller as it scythes through your pinkies at 8K RPM plus!

Safety lecture over, let’s see what makes the ASP 180 tick then, starting with a general overview and appraisal. The engine is almost identical to the 30 to120 versions that preceded it and as their heritage is well known, it should be fairly clear to all that this is not a cutting edge design in this the 21st century, and neither does it need to be. Case in point, underneath all of that plumbing and electronic wizardry beneath the bonnet of your new car lies a crude poppet valve “Otto” engine that dates back to the 19th century, design wise and it’s fair to say that until someone comes up with a better solution (and many have tried and failed) we will keep on using them. For a model aeroplane the rationale is even simpler because we care not a jot about pollution, economy or any other eco friendly planet hugging mandate. We want is power and reliability, with the latter more important than the former. Longevity is a bonus and if the engine is smooth running and throttles well, then for an aeromodeller, that is model engine nirvana!

The ASP 180 has a very nicely finished set of investment castings holding all the innards in place and to pick the unit up and handle it immediately bestows an appreciation of how nicely made the 180 is. The general feel of the castings and the overall look of the various fittings and fixings good to very good, unsurprisingly it must be said given recent ASP experiences with other units in their increasingly prolific range. The engine arrived in a standard good quality identifiable box, complete with the usual silencer and a pair of Allen wrenches, plus the instruction sheets. Let’s take a look at the latter first then (always wise)!

Instructions are seldom perfect, with some on the dire side of basic and just occasionally, pretty darned comprehensive. Paul Landels at Just Engines – the ASP distributors – take a little time and trouble over this facet of retailing model engines, adding their own input where deemed necessary. In the case of the 180, the factory instructions seem to have been replaced entirely with Just Engines own! These include, running in and general care advice, plugs, fuels and lubricants, mounting and fixing advice, carb adjustment propeller fitments and warranty details. There is also a section on tappet adjustment for the four stroke range which is useful. You should note the “P L E A S E read” header - plea from the heart and one that I heartily endorse. It constantly astonishes me that folks spend hard earned cash on model engines and then just do their own thing or worse still, follow the (conflicting) advice of a mate and ignore the supplier’s words. If you follow the instructions and something falls off, then the supplier will always put things right but if you wing it yourself thinking that you know better, when push comes to shove you could be up the proverbial.

Given that this was one of only a few 180’s in the country at the time and with a deadline to meet I decided not to even partially dismantle the engine. The inner details will be very well known to most by now as this design is replicated by several companies in sizes ranging from about 4cc to 30cc. To take the test unit apart risked putting the engine out of commission should something go amiss and for the fiddlers out there, be aware that a four stroke is far more complicated than its two stroke brother with lots of bits to wrongly orientate and tight fits here and there. Never ever take your engines apart during the warranty period regardless. I dismantle, literally hundreds of engines a year and I still get the odd one that refuses to separate in the intended or expected way, this invariably being down to tolerances or gumming and corrosion with engines that have seen some use so if possible, never disturb a running engine anyway!

With the engine set up on the test rig I grabbed a couple of recommended propeller sizes, which are 16 x 8 to 18 x 6, i.e. the sort of sizes that you might fit to a two stroke petrol engine of similar capacity. The inference here is that there is something like 2.5 BHP and more on tap and that equates to very useful urge for those quarter scale aerobatic jobs like the big Extra’s and Cap’s etc! Fuels for four stroke glows are of the “mainly synthetic with nitro” variety and I have my own “general rule” and it is exactly that - just a general rule - for four strokes! Four strokes enjoy one power stroke in four (the clue is in the term….) which means the other three are just wearing it out – or more seriously, cooling the plug in our glow environment. Because of this I advocate using fuels with a Nitromethane content of at least 5-10%. This is by no means definitive but my thinking, based on personal experience, is that synthetic lubricants keep your four strokes from gumming and coking up which unfortunately, is particularly marked when running Castor, whilst a healthy splash of Nitro methane helps to keep the fires burning. Running even higher nitro in four strokes can be very beneficial and give higher power but beware, because this isn’t always the way to go. Running 10% usually proves fine for most and it’s a good yardstick, although I note in the instructions Just Engines recommend 5% nitro (which I would treat as the absolute minimum ordinarily but this is a big engine) and a sniff of castor in synthetic based fuels. As always, follow the advice of the instructions supplied with any engine that you buy.

Setting the 180 up on the test stand was the usual five minute job and with a new OS “F” plug fitted the tank was filled and with a half dozen chokes on the inlet – the glow was energised. With my trusty gardening glove (i.e. the one with numerous propeller cuts that would have otherwise sliced into my pinkies……..) donned, I grabbed the 18 x 6 propeller that I had chosen for the first starts and a reassuring bump was felt as TDC was cleared. Hang on a minute – the props moved? I did it again and sure enough – the prop was now another ten minutes around the clock face – something strange was going on. The problem was simple (and obvious) – the Woodruff key that secures the prop driver in place was in the box and not on the end of the crankshaft where it was needed. Just be aware that these can drop out during transit then. With everything sorted the engine started so very easily with one reverse bounce of the prop against compression. Running slobberingly rich and producing lots of reassuring smoke, the 180 settled immediately into a steady fast idle and I let it run at that for around two minutes before tweaking the throttle to about one third. Hey hey – that’s a lot of air moving and what a beauty this one is and no mistake. The 180 refused to die or misfire at ridiculously low RPM and immediately responded to the throttle lever, and this all on a really rich setting with no time on the meter at all. This certainly bodes well for aerobatic low level reliability and I have to say, with that sort of response, allied to the sheer delight of the sound and feel of a big four stroke like this one, petrol two strokes do seem a rather attractive and far les sophisticated alternative.

I let the engine cool and then restarted it for another run, which was pretty straight-forward, producing the same immediate start. The trick of easy hand starts with a four stroke is to really choke the engine til it won’t turn over – or barely anyway, before turning the prop backwards a couple of times to drain the excess. One flick against compression the wrong way will almost certainly do the trick with the plug then energised. Four strokes will never start unless they are really wet and you can flick and spin the thing round like a tumble drier but until you wet the cylinder, you are wasting your time.

The 180 sounded completely happy after just ten minutes and a very easy 8000 RPM came up on the tacho, running a “club” of an old Dynathrust 18 x 6 glass nylon two blader. 8000 RPM is probably about where you want to run this one and that would indicate 16 x 8 – 17 x 7 (is there such an animal…?) 18 x 6 and so on. Put the 180 up front in a WW1 Sopwith or the like and you may find a wooden 20 x 6 effective for that sort of aeroplane. I wouldn’t advocate more than 8 inches of pitch nor less than 16 inches of diameter for this one and that’s about it for props. Engines like the ASP 180 have very definite and singular applications (i.e. sports aerobatic/scale) meaning that there is little point in exploring the performance envelope further. Over 10K RPM and things are getting a bit frenetic on an engine of this stature and below say, 6000, you are asking it to “grunt” a bit, which is as damaging in its own way as excessive RPM (more so for the big end probably)!

With the second tank run through, I felt perfectly at ease with the ASP 180 and after screwing a 15 x 8 APC propeller to it, which it turned at a very healthy 9450 RPM (indicating that this was a prop too far…) that was that. Everything panned out famously, as they say and I have no negative issues at all with this rather nice engine. At the price (half the cost of some similar sized four stroke units) this one is a definite bargain and I can picture a pair of them on a large Mosquito where they would undoubtedly, not only go well but the sound would be fantastic. More realistically, I am going to put this one in a Zlin 526 – previously earmarked for my very nice Laser 300 Vee but that one now has another home. The ASP 180 is going to be so very nice in the Zlin and should endow it with exactly the sort of characteristics that the model demands, namely smooth and predictable power and certainly, the 526 doesn’t need (or want) the snappy responsive behaviour of a large two stroke glow. I have another 526 of identical proportions and that one flies very nicely on a 35cc petrol, so the ASP 180 will pull it round “for fun” so to speak!

What more can I say then? The ASP 180 does “exactly what it says on the can” and at a bargain price – it’s a bit like getting an Aston Martin for the price of a Fiat Panda – not bad, don’t mind if I do!

Prop Figures

18 x 6 Dynathrust 8000 RPM
16 x 8 APC 8400 RPM
15 x 8 APC 9450 RPM

Fuel used for all tests - Weston Prosynth 2000 10% Nitromethane content
Plug - OS F
Weather - warm dry summer day 22 C

ASP 1.80FS;
* fits in a 1.20 mount
* swings 18" props with authority
* superb value for money

Read what Malc Pinnock had to say about the A.S.P 1.80fs in RCM&E here

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