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The Aster A3 

‘Flying Scotsman’


A review by

Geoff Calver



The release of a new British outline model from Aster is always greeted with great interest and anticipation from Gauge One enthusiasts, not only in the UK but the world over. Following many months of rumor and speculation, the announcement was finally made that the next model was indeed to be the famous Gresley LNER A3 ‘Flying Scotsman’, an engine that many had thought long overdue for Aster to produce. Here certainly was a prototype that would have wide international appeal as one of the most famous and widely traveled locomotives in the world.


The model has been produced initially as a limited edition of 230 factory-assembled and kit examples worldwide. The following article does not set out to describe a blow-by-blow account of the construction of the model, but rather to offer some general observations about constructing the kit version and the experience of applying a degree of customization in the process.


Back in the 1980’s, Aster had successfully produced the legendary Gresley 3-cylinder A4 in three versions and examples of these models are highly sought after today by collectors with many still to be seen running regularly at Gauge One events.

However, modeling a prototype as well known and documented as Flying Scotsman must have presented the designers with somewhat of a dilemma, insomuch that 4472 has been running more or less consistently in private ownership for nearly forty years. This equals the combined period it spent in LNER & BR ownership, during which it underwent a myriad of changes and alterations from an original member of the A1 class into the eventual and familiar A3 form at the time it was taken into private ownership. This process of alteration and modification has continued in preservation right up to the present day. For example, in its current form with double chimney and smoke deflectors, 4472 is able to perform at maximum efficiency, but in this writer’s opinion the overall effect together with the original style of LNER livery is somewhat incongruous to say the least!


With these considerations in mind, Aster have perhaps wisely decided to offer some scope to the modeler by offering the model as an A3, but retaining right hand drive, as many did until well into the 1950’s. It is also fitted with a corridor tender as with the preserved example and to many of the class during their early years employed in hauling the original non-stop ‘Flying Scotsman’ expresses from Kings Cross to Edinburgh.


In my opinion, Aster has done a magnificent job in capturing the subtle proportions of the A3 with its distinctive tapered boiler cladding shapes. The finish is superb, with a plethora of fine detail as the pictures illustrate.


The agonizing bit


As a dedicated LNER enthusiast, this was a model that I simply could not resist and despite the initial pain in the wallet, I decided that I would take the kit version, which is my normal preference.


As is usual with Aster, the engine is offered either as a factory assembled RTR model, or as a kit for those who prefer to assemble the model themselves and hence to learn much about it’s design and operation in the process. In this case, the RTR versions are finished as No. 4472 Flying Scotsman and are fully lined, numbered and lettered in LNER apple green. In a somewhat new departure for Aster, the UK kit versions are not lettered or numbered, but are supplied with separate sheets of waterslide transfers so that the owner may finish the model in the name and number of his or her own choice and thereby begin the process of customizing their model. Nameplates for ‘Flying Scotsman’ are provided.


For simplicity, I decided that I would construct and finish my model as one of the earlier series that was built originally as an A1 ‘Pacific,’ but later converted to an A3 retaining RH drive. It would also have to represent one of the locomotives known to have carried an early series corridor tender. Here I embarked upon what turned out to be the complex task of researching the many detail variations and developments of this famous class of locomotives. In the end, I narrowed the options down to one or two examples that seemed to fit the bill and eventually settled on No. 2580 ‘Shotover’ as my choice.


This was one of the engines that definitely carried the corridor tender for a short while after rebuilding into an A3 and also served as somewhat of a ‘guinea pig’ for a range of other experiments, such as the addition of Westinghouse brakes and the disfiguring ACFI water feed apparatus. However, in the fullness of time these unsightly appendages were removed and ‘Shotover’ returned to the more familiar guise of an A3. After all this extensive research and cross-referencing, it was time for a reality check. A model is always a compromise to some degree, so once the name and number were chosen it seemed sensible to just relax and get on with the pleasurable part, lest the men in white coats be summoned to take me away for my own good!


As I had decided to customize my model, it seemed sensible to consider more than just a name and number change. Those who know me will know that I am not a great fan of shiny wheel rims and bosses on model locomotives of any gauge, unless of course the prototype calls for it. I believe that the effect can often result in a toy-like appearance and detract from the overall realism, however I know many individuals who are of the totally opposite opinion! 


Aster are justly proud of their finely cast and beautifully machined locomotive wheels, but the appearance of all that highly polished stainless steel gave me course for concern. The full LNER livery calls for black edges to the wheel rims with white lining inside and therefore I undertook this task before construction of the model. I leave it to you to decide if this was all worthwhile by comparing the pictures of ‘Shotover’ against a standard factory assembled version.  


The Design  


The erstwhile Aster A4 design employed a novel layout whereby the outside cylinders employed two sets of fully working Walschaert’s valve gear, but the inside cylinder was driven by a simple slip-eccentric arrangement with fixed cut-off. There has been much debate over the years as to the merits of this design and many ‘modifications’ to the models have been performed to enhance their performance, but in reality the original design performed perfectly satisfactorily if properly assembled and adjusted. The new Aster A3 has taken this evolution a stage further and employed the prototypical Gresley/Holcroft derived 2:1 ratio conjugation system to drive the middle engine valve events.  


I am fortunate in that I have had the opportunity to assemble a number of Aster kits previously, both for myself and others, so am reasonably familiar with the process. It would be unfair to describe construction from the viewpoint of a beginner, but I see no reason why a novice could not attempt construction, given the amount of experience and help available throughout the hobby, not to mention the superb back up and advice available from Aster Hobbies. After all, my first attempt was an A4 back in the mid ‘80’s – a relatively complicated model by the standards of the day. I still have that A4 and it still performs very well even to this day.  


The kit is well packaged with exploded view drawings and step-by-step constructional details. Assembly proceeds by following a logical sequence of numbered sections and the packaging comprises a number of smaller boxes containing the parts for that particular section. All fixings are supplied, as are basic tools for assembly, although it will be necessary to have to hand a range of normal modelers’ tools such as Swiss files, tweezers, etc.  




The first, and in many ways, most vital task of any Aster kit construction involves the lapping of the cylinder port faces and slide valves.  This is necessary to remove any roughness left by the milling cutters and to ensure that the slide valves achieve a good seal as they pass over the steam ports.  A piece of 1000 grit wet ‘n dry paper is included in the kit, which is wetted and laid on a flat surface (I use a piece of plate glass) for the process of lapping by applying a ‘fore and aft’ motion to the inverted cylinder.  Great care is needed to apply even pressure during this process; otherwise the resulting surface may not be perfectly flat, especially at the corners.  A bit of extra effort here will result in a very smooth running engine right from the outset, which is its own reward.  


As the construction sequence calls for the fitting of the main driving wheels at an early stage, as mentioned previously it was necessary to paint and line the wheels before construction commenced. There is always a great temptation to just to dip into the kit and complete whichever item takes your fancy, but this is not recommended for a beginner. There are often good reasons why the assembly sequence should be followed as prescribed in the instructions to help avoid problems further down line.  


At this stage the cylinders are assembled to the frames together with the prototypical Gresley/Holcroft 2:1 conjugated valve gear mechanism. The centre cylinder is mounted with the port face facing downward i.e. with the steam chest underneath the cylinder. This also enables easy access to the slide valve for setting purposes. With the cylinders in place and slide valves roughly positioned on their spindles, slide bars, coupling rods and valve gear can be fitted. Unlike some previous kits I have assembled, I was delighted by the excellent fit of most of the parts on the Aster A3, with only a minimum of adjustment required to achieve a freely running chassis.  


With the motion now fully assembled, timing of the valve events can take place with special attention to the setting of the return cranks. Following my usual method of determining this setting and double-checking with a home made protractor to the required angle, I was relieved to observe that the derived middle cylinder valve events appeared to be spot on. At this point it is time to secure the steam chest covers and give the engine a rolling chassis test with compressed air - I usually use a small airbrush compressor for this task. Plenty of light machine oil in the cylinders is required here to avoid premature wear to the valves and pistons. Prolonged periods of running the chassis on air are to be avoided – the object is primarily to prove the valve settings and reveal any tight spots in the motion that may need attention.   


The boiler design is of the familiar and well proven ‘C’ type with two main flue tubes and a ‘dry’ firebox. Assembly of the boiler fittings is quite straightforward and a nice touch here is the fire hole door detail on the backhead, with a transparent mica insert through which the meths fire may be observed.  

The remainder of the assembly work concentrates on fitting the boiler into the tapered outer casing, attachment of all of the foot plating and various appendages plus construction of the tender. I decided to tone down the bright brass fitments to a more realistic appearance by applying a light amount of ‘brass blacking’. The pictures illustrate the effect far better than I could describe in words.


The model is realistically painted in a slightly light shade of LNER ‘ Doncaster ’ apple green and appropriately lined, although surprisingly the cab front spectacle plate window surrounds were not. As this is quite a distinctive feature of LNER locomotives, I decided to line around the windows and also the boiler wash out plugs for extra effect. For lining, I used a combination of my trusty ‘Bob Moore’s’ lining pen, together with the compass bow pen for the wheels.  


I also added the prototypical black/white lining to the front tender plate and a dummy coal load was made up out of odd pieces of balsa wood glued together and covered with a cocktail of crushed coal mixed with dilute PVA. As my model is finished as No 2580 ‘Shotover’, it was necessary to fit the round North British round builder plates to the sides of the smokebox instead of the oval Doncaster-built plates supplied for 4472.  


I always keep a log of the amount of time I spend on each stage of kit assembly, together with general construction notes (about 100 hours total for this particular model). Minor errors in the Aster construction books were easily spotted and corrected and, as a result of user feedback, Aster Hobbies Ltd in the UK have produced a ‘tuning tips’ guide detailing a list of small points to watch out for.  


Does it go?  


I’ll say it does!  Following a successful hydraulic test of the boiler and fittings, the initial steaming was performed on my rolling road. With working pressure of about 4 bar (60psi) on the gauge, the regulator was opened and ‘Shotover’ moved its wheels under steam for the first time.  To my relief, the engine ran very sweetly and steamed well, responding positively to a little ‘notching up’ of the valve gear.  


The next test was out on the track on a fairly cold and windy day. After a few warm up laps, six LNER Gresley teak carriages were attached and off she went, seemingly unaware of the load. The distinctive three-cylinder exhaust beat became evident for the first time as the engine circled the track for about an hour. The following day offered an opportunity to run on an extensive indoor layout with wider radius curves. With several G1 worthies on hand keeping a critical eye on proceedings, the engine fairly flew around the track with that same train and all agreed that it was a superb performer. It was starting to develop much more power as the running-in process progressed and I retired a happy man. I have since observed several other A3’s giving similar performances.  


Final thoughts  


There can be no doubt that the Aster A3 is an excellent model and congratulations are due to all those involved in its design and construction. It has been an obvious commercial success, as evidenced by the rapid sell-out of the initial batch. If you missed the opportunity to acquire one, the good news is that there is to be a further smaller batch produced, examples of which should be available at about the time this article appears in print. Undeniably, these models represent a not inconsiderable investment for the average garden railway enthusiast; however the excellent investment value of Aster models is well recognized and therefore in my opinion this model could easily become one of the most sought after examples of all time.  


I  am certain that Sir Nigel would have been very proud!


This article originally appeared in Issue No. 101 of Garden Rail.  Appreciation for permission to reproduce it on SouthernSteamTrains.com is expressed to Geoff Calver, author, photographer and G1MRA webmaster 





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