The Fuji Story

by Adrian Duncan



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  Chapter 1—Historical Background
  Chapter 2—Fuji Corporate History
  Chapter 3—Fuji in the '50's: The Classic 099 Series
  Chapter 4—The Classic Fuji 099 Series in the Sixties
    13th Model, Fuji .099 (Model 099-13)
    14th Model, Fuji .099S (Model 099-14)
    An Intriguing Offshoot: the Fuji .12
    15th Model, Fuji .099 (Model 099-15)
    16th Model, Fuji .099: the Fuji 099J-II (Model 099-16)
    End of the Twin-stacks: the Fuji .099S-II (Model 099-17)

In Chapter 3, we followed the history of the Fuji marque from its beginnings in 1949 through the development and expansion phase that characterised the decade of the 1950's. We did so by following the development of the company's .099 cuin models, since that series was clearly among the most important product lines in the company's portfolio and drew a great deal of attention from a developmental standpoint.

We left the story in late 1958 at a time when Fuji had just released the twelfth variant of its .099 cuin model, which was the seventh member of that series to carry the association with Menasco. As events were to prove, that association was now about to come to an end. Let's continue our in-depth look at the further development of the Fuji .099 series.

13th Model, Fuji .099 (Model 099-13)

All twelve models of the Fuji .099 described in Chapter 3 had featured a conventional tapering bracing gusset beneath the main bearing. As the attached illustrations will have shown, this varied in size between models but had always been there. However, this changed at some indeterminate point, likely in 1959, when a further variant was introduced which had a very thick rectangular gusset located beneath the main bearing. Illustrated engine number 95696 typifies this model.

We are presently unclear regarding the purpose of the protrusion beneath the main bearing—it appears to be less than ideal for use as a pressure tapping point. Perhaps it was for mounting a starter spring? This notion seems to be contradicted by the fact that the contemporary twin-stack models of the Fuji 15 and 19 also featured a similar protrusion in the same location. Perhaps some kind reader can enlighten us.

But this wasn't the only change. At long last, this model saw the final elimination of the rather vulnerable "twin expansion" mounting lugs in favor of conventional solid lugs of quite substantial dimensions. About time—a change that was long overdue, in my personal opinion! This one improvement made the engine far less susceptible to crash damage.

The revised case also featured a main bearing that was significantly longer than that of the earlier models. Coupled with a substantially longer prop driver, this placed the airscrew considerably further forward from the axis of the cylinder and also increased the distance between the needle valve control and the airscrew—a welcome operator safety improvement. The "collar" which had formerly appeared at the front of the main bearing was no longer in evidence. Another innovation was the appearance of a pair of cast-in stiffening "pillars", one on each side, which were centrally located inside each of the twin stacks. The revised crankcase casting was finished by tumbling.

Another change was the elimination of the split-thimble needle valve assembly which had been used on all previous Fuji .099 models in favor of a far more dependable unit using a knurled thimble which was tensioned with a single-leaf spring clip. This design was to appear on all subsequent Fuji .099 models during the "classic" era with which we are concerned. It is extremely stable in use and holds its setting perfectly at all times.

The blind-bored cylinder and plain unfinned cylinder head which had first appeared on the previous model were both carried over to this new variant. The far more secure method of swaging the head onto the cylinder which had been introduced on the previous model was also retained.

This model is highly significant for two reasons. Firstly, it was destined to become the final Fuji .099 model to feature radial cylinder porting. Secondly, its introduction marked the end of the lengthy association of the Fuji .099 series with the Menasco name. The revised crankcase merely has "1.6 cc" cast into the left side of the case where the "Menasco" name used to be. The right side continues to bear the identification "Fuji 099". Presumably by this time Menasco had been out of the air racing business for so long that the name association had lost any sales value that it might have had in the early 1950's. The right-hand side of the case carried the identification "FUJI 099".

An illustration in a Fuji brochure from this period shows an example of this variant bearing the clearly legible serial number 15897. The fact that we have illustrated engine number 95696 on hand implies that this variant was produced in quite significant numbers over a period of some years. Indeed, this may have been the Fuji .099 twin-stack model that remained in production for the longest period of any such model—present indications are that it was to remain in production until 1965.

As noted at the close of Chapter 3, Fuji Bussan had now clearly made arrangements for a quantum expansion of the production capacity for the Fuji range. It's entirely possible that Tannan Industrial had already assumed full responsibility for Fuji production, although we can't state this as a fact on the basis of present information. Regardless, the serial numbers quoted in the previous paragraph confirm the manufacture of over 96,000 examples of the new .099 cuin model during its apparent six-year production life—a very impressive rate of 16,000 units per year, which is far in excess of previous production figures based on known serial numbers. Where are they all now?

As far as I am aware, no test of any of the radial-ported Fuji .099 models described so far was ever published in the English-language modelling media. The manufacturers claimed an output of 0.15 BHP @ 13,000 rpm for the model just described. This seems a bit optimistic to me, although I must say that the engines do perform quite adequately for general-purpose use. My own test of "Menasco" Fuji engine number 2031 (Model 099-9) confirmed that it turns a 7x4 Taipan G/F prop very comfortably at a steady 12,500 rpm on 15% nitro fuel, implying an output at that speed of around 0.13 BHP based on an estimated power coefficient for that prop—a little down on the manufacturer's claim, but not outrageously so. Starting is very easy, running is ultra-smooth and the engine needles extremely well.

By this time too the other engines in the Fuji range had been joined by a .061 cuin model which was basically a bored-out version of the established .049 model. Both the .049 and .061 models had now acquired radial tank mounts and were also available in well-crafted outboard motor versions for marine enthusiasts. These display a virtuosic command of the die-casting process and are prized collectors' items today along with the .15 cuin "Seahorse" outboard models which came later. It's worth reminding ourselves in passing that Fuji used yet another company name on the boxes in which these outboards were supplied—the "Fuji Engine Mfg. Co".

14th Model, Fuji .099S (Model 099-14)

The model 099-13 described in the previous section appears to have sold well and to have remained in production into the mid-1960's. However, by the early 1960's the writing was clearly on the wall for the old twin-stack radial-ported .099. The performance of the various competing .099 models had by now far eclipsed that of the venerable twin-stack Fuji with its increasingly anachronistic porting coupled with a relatively inefficient combustion chamber, and the company must have recognized that they would have to further update their design or eventually be forced out of the 09 field.

O.S. had persevered for some years with their 1951 "New .099" model which bore a striking resemblance to the Menasco Fuji .099 models (or more likely vice versa!). However, by 1957 they had replaced this offering with the completely revised Pet .099 model, and followed this up in 1959 with a much-improved version of this model in the form of the low-priced Pet-II. This was real competition for Fuji in the "economy" market which was their main rice bowl! It very likely prompted the 1959 introduction of the Fuji 099-13 model just described.

Enya had waited until 1954 to enter the .099 field with their excellent Model 3001. This fine little engine left the starting gate in such good fettle that it lasted until 1959, when it was replaced by the greatly improved Enya 09-II which dispensed with a cast-in bypass bulge in favour of bypass passages milled directly into the walls of a very thick lower cylinder. It was probably this model which goaded O.S. into upgrading their Pet model into its Pet-II configuration—the rivalry between Enya and O.S. was never less than spirited! Enya took a further step forward in 1963 with their truly outstanding short-stroke 09-III model which could give the Cox Tee Dee .09 a good run for its money, and this in turn encouraged O.S. to develop their Max-10 model which appeared in the following year.

As a result of all of the above activity, by the early 1960's the O.S. and Enya companies were going from strength to strength, both having extremely competitive .099 models of their own with which Fuji would have to compete. K.O. was also still in the field at this time with their own .099 models, both diesel and glow. The Hope, Boxer, and Mamiya engines were no longer on the market, but the foreign and domestic competition facing Fuji was still formidable.

Throughout this period, Fuji had stood pat with their existing and increasingly venerable radial port twin-stack .099 models, making only the relatively minor changes documented above as time went by. We noted earlier that they had long since abandoned any pretence of trying to compete with the likes of O.S. and Enya in the performance arena. Instead, they had positioned themselves in the marketplace as suppliers of dependable low-priced general-purpose engines which were well-made and represented outstanding value for money for the average sport flier who was not concerned with ultimate performance.

However, with the kind of performance advances coupled with lower prices now being achieved by their major Japanese competitors, the performance gap was becoming too wide to justify the marginally lower cost of the Fuji model. Accordingly, some kind of movement on the part of Fuji became inevitable if they wished to remain in the .099 field.

It's clear from subsequent events that the company was very attached to the twin-stack .099 layout with which their name had become so closely identified. This being the case, their first thought would doubtless have been to update their existing twin-stack model. However, it would have been painfully apparent to them at the outset that to accomplish this they would have to switch from radial porting to a more efficient scavenging system. It would have been equally clear that the retention of the twin-stack configuration represented a significant impediment to the upgrading of that system. In effect, the Fuji twin-stack design was approaching the end of its development road. The Fuji designers clearly recognized this. But they had to do something, and they had to do it fast!

So before tackling the development of an updated twin-stack model, the company decided to hedge its bets and pursue the path of least resistance by introducing its first "conventional" loop-scavenged .099 model—the .099S. This model appears to have been introduced in 1964 or thereabouts, certainly some time prior to the introduction of the revised twin-stack model to be described below. This is confirmed by the appearance of the .099S in one of Fuji's leaflets alongside the Fuji .099 model 099-13 described in the previous section. The .099S was thus chronologically the fourteenth model of the Fuji .099, and is accordingly identified under our model numbering system as the Model 099-14. It was also the first Fuji .099 model to be identified by the manufacturer as anything other than the Fuji .099!

The serial numbers of the two examples in my possession are A62143 and A62336. It appears from this that the letter A was added to the serial number sequence for this model to distinguish it from its twin-stack companions. These numbers also confirms that the 099S was manufactured in substantial quantities. Since they lie in the middle of the known serial number range for the previous variant, it seems to be a logical deduction that the serial numbering sequence was re-started at A1.

Like the larger models in the updated range, the .099S was an Enya-inspired design very reminiscent of the highly-regarded Enya 09-II which had remained in production until 1963. It used a conventional baffle piston with a die-cast contour-matched finned head and a plain drop-in steel cylinder liner with both the transfers and the exhaust ports located in their "conventional" positions at opposite sides of the engine. Like the Enya, it utilized a very thick cylinder wall which incorporated a pair of internally-milled bypass passages. It also used an Enya-style bolt-on main bearing housing.

The main casting was a completely conventional die-cast component incorporating the exhaust stack located on the right-hand side as well as the cooling fins above the stack and an integrally-cast backplate. The shallow "bypass bulge" on the left side of the main casting was a dummy.

Naturally, the distinctive twin stacks were gone, and the needle valve had been amended from its former rigid design to a flexible spring set-up along the lines of those which had been used for years by Enya and O.S. The integrally cast bell-mouth venturi had also gone, being replaced by a tubular stub intake which could accept either a control-line venturi or an R/C throttle. The earliest examples of the new model had machined light alloy venturi inserts, while later examples featured moulded plastic inserts. Initially these plastic inserts were of the same bright green material that was used on the next version of the twin-stack model (to be described in a following section), but later examples like the one illustrated had black plastic inserts.

An R/C version of this model was naturally offered—indeed, it was evidently to facilitate this that the venturi arrangements had been revised. By this time the R/C market had effectively supplanted the control-line and free flight markets as the primary target for model engine manufacturers worldwide. A very neat muffler was also developed. Interestingly enough, this was rather cleverly designed to fit the various side-stack Fuji models from .099 to .15 cuin.

Despite the absence of a tank, weight had crept up further to 3.8 ounces, mainly due to the massive cylinder liner. The one thing that remained unchanged in this design was the bore/stroke combination—still at the same 12.70 mm and 12.70 mm for an unchanged displacement of 1.61 cc (0.098 cuin.).

Unfortunately, the changes resulted in an engine which, while in theory offering a rather higher performance potential than its twin-stack companion due to the more direct bypass and the more efficient combustion chamber, completely lacked the individuality of the twin-stack models with which Fuji had become universally associated. For me, and I suspect for many other aficionados of Japanese engines, the advent of the .099S represented the final irrevocable step towards the elimination of the technical distinctiveness of the Fuji line-up. Most of the other engines in the Fuji line-up had by then become Enya clones, and now the .099 series was clearly well on the way towards joining them. In essence, the .099S differed little from the competing products of other Japanese makers. In fact, from a short distance one could scarcely distinguish this engine from its Enya, O.S. and recently-introduced Ueda competition!

The makers claimed an output of 0.25 BHP at 13,000 rpm for the .099S, which frankly appeared extremely optimistic to myself and others at the time. Thankfully, the .099S was the subject of a test by Peter Chinn, which was published in the April 1967 issue of Aeromodeller magazine. This certainly set the record straight with a vengeance—Chinn was only able to measure a very modest output of 0.105 BHP@ 11,400 rpm with a standard Fuji muffler fitted and running on 5% nitro fuel. Some spot checks with 25% nitro fuel indicated perhaps a 10-12% increase in output, which still fell very far short of the maker's claims. On the plus side, Chinn found that the Fuji muffler made virtually no difference to performance—a very positive finding in an increasingly noise-conscious world.

Chinn characterized the .099S as an engine which was "easy to handle" and which had "a performance that the average modeller should find fully adequate". He characterized the engine overall as "soundly made, reasonably priced and not in the least tricky to handle". Despite these positive comments, it seems clear when reading between the lines that Chinn found this engine somewhat less than inspiring ...

One interesting comment made by Chinn in his write-up of this test was the statement (written in early 1967) that the Fuji range had been "manufactured for about a dozen years", i.e., since 1954/1955! We know that this is in error by a good 5 years, and this reinforces the view that Chinn really only became aware of the Fuji range in about 1955 and remained more or less unaware of the range's very interesting history prior to that time. Doubtless the language barrier had a lot to do with this.

Chinn also commented that the Fuji range was not widely distributed in the US and Europe and that the UK was at this time (1967) one of their major export markets. He named the then-current UK distributors as the large Hobbies Ltd. organization. It seems that this firm had only recently assumed the Fuji distributorship, since a June 1966 article in Radio Modeller regarding the Fuji 15-III had named the UK Fuji distributors at that time as Enterprise Model Aircraft Supplies of Manchester.

An Intriguing Offshoot: the Fuji .12

Although it doesn't fit precisely into the displacement category presently under study, it seems appropriate at this point to include a comment about another Fuji model that was directly related to the Fuji .099S just described. This is the rather oddly-sized Fuji .12 design. This model was externally identical to the Fuji .099S, being based on the same main casting and having the same mounting bolt pattern. It was in fact interchangeable with the 099S in the same airframe. In view of this, it is most conveniently treated as a member of the .099 family.

The Fuji .12 appears to have been introduced more or less concurrently with the .099S or very soon thereafter—Fuji prepared a separate leaflet which was included as a supplement in some of their engine boxes at a time when the Model 099-13 was still current and which showed both the 099S and the .12 together. Based on this evidence, an introductory date of 1964 or perhaps early 1965 appears most probable.

This engine had an actual displacement of 1.975 cc (.1205 cuin), a figure which had not been widely used since the early days of post-war model engine manufacturing because it did not correspond to any of the recognized competition classes. Most unusually, the additional displacement was achieved by increasing both the bore and the stroke of the 099S by 0.9 mm to a figure of 13.6 mm apiece. The result was an engine which retained the perfectly square bore and stroke measurements of its smaller relative as well as its main design features.

In appearance, the .12 was very similar to the 099S apart from being a little taller on account of the longer stroke. It might be easy to suppose from this that the two models shared most of their components, but in fact this was not the case—the .12 was an all-new production which merely used the same main casting as its smaller relative, and even that component was machined to different specifications. Very few of the .12's components were interchangeable with those of the smaller model.

The Fuji .12 was the subject of yet another test by Peter Chinn which appeared in the August 1969 issue of Aeromodeller magazine. Chinn appears to have been rather more favourably impressed with this offering than he had been two years earlier with the 099S. He found that the 23% increase in displacement had yielded nearly 30% more power, while the weight of the engine had increased by a mere 0.3 ounces, from 3.8 ounces to 4.1 ounces (without silencer). The result was a significant improvement in the power-to-weight ratio. Chinn measured an output of 0.145 BHP @ 13,000 rpm for this model, using the same fuel as in his previous 099S test.

The above figures offer a clue as to the intended market for the .12 with its rather odd displacement. It was clearly aimed at sport fliers who wanted a little more power from an easy-to-handle and lightweight glow motor of typical 1.5 cc size and weight. The fact that its mounting was interchangeable with that of the 099S meant that anyone finding that the smaller engine did not provide sufficient urge now had an easy upgrade available. Chinn specifically noted this in his report. Setting aside the displacement difference, the .12 was in effect the "high performance option" in the context of the mid-1960's Fuji .099 range.

Viewed in this light, it's hard to escape the impression that the creation of the .12 may have been a stop-gap measure stemming from Fuji's realization that their new 099S model still fell far short of matching the performance of the contemporary .099 models being offered by their chief rivals. The addition of some extra displacement may well have been recognised as the line of least resistance when it came to the quick creation of a higher-performance engine that remained suitable for sport models intended for the .099 cuin displacement category.

Chinn also commented that the UK distributor of the Fuji engines had changed yet again. As of 1967, when he had tested the 099S, the UK distributors had been Hobbies Ltd., but in his 1969 test of the .12, Chinn reported that the Fuji range was now being distributed by Mainstream Productions. It appears from this that Fuji was experiencing some difficulty in retaining a UK distributor—they had gone through at least three distributors during the period 1966—1969.

It actually seems possible that the .12 had not been well received in the world marketplace, perhaps due to its rather odd displacement, and its relatively late appearance on the British market in 1969 may have represented an attempt by the makers to unload surplus unsold stocks of this model onto the British market, which was by then becoming one of Fuji's more significant overseas sales areas. If this was so, actual production may well have ceased by that time. It may be significant that the .12 never seems to have appeared as a full-time member of the Fuji line-up depicted on the leaflets which came with their engines—its appearances were evidently confined to the supplementary leaflet illustrated earlier. This implies a relatively short period of actual production followed by a fairly lengthy sell-off period. Time now to return to our review of the main Fuji .099 series.

15th Model, Fuji .099 (Model 099-15)

Some measure of the affection with which the Fuji company viewed their venerable twin-stack .099 series may be gained from the fact that with the conventional and potentially superior .099S and .12 models in production they had the updated .099-class products that they needed and could simply have allowed their old twin-stack workhorse to fade quietly away while further developing the .099S as necessary. However, they did not do this—on the contrary, with the .099S now established as a member of their range, Fuji immediately directed their attention and resources towards making yet another stab at creating an upgraded version of their "flagship" twin-stack .099 model.

It's not completely clear when the Fuji .099 twin-stack model 099-13 described earlier was finally supplanted by the drastically revised twin-stack model to be described next, but it was most likely sometime in 1965. The reasons for our proposing this date are complex, but we find them quite convincing and will continue to do so until someone proves us wrong! Let's see if we can convince you ...

The 1962 Global Engine Review published at the end of that year by American Modeller magazine (almost certainly authored by Peter Chinn) noted specifically that as of 1962 the radial ported version of the Fuji .099 (and the Fuji 15, for that matter) remained in production. Now, I have a Fuji instruction leaflet (with an NIB Fuji .099 Model 099-15 of the type to be described in the present section) which shows a Fuji .099 model 099-13 as described above alongside the loop-scavenged Fuji 15-III model which replaced the old radial port twin-stack Fuji 15. The 15-III undoubtedly first appeared in 1964 (based on information extracted from "American Modeller's" 1964 Global Engine Review, again authored by Chinn), so it would appear that the model 099-13 was still current as of 1964 and possibly for some time thereafter.

However by 1966 the twin-stack model 099-13 described earlier had unquestionably been replaced by the twin-stack fifteenth model of the Fuji .099 (model 099-15) to be described next. We are able to make this assertion with great confidence based upon the fact that the model 099-15 was mentioned and illustrated in an article which appeared in the British magazine Radio Modeller in December 1966. There was no indication in that article that it was a recent introduction. A similar report on the same engine published in the February 1967 issue of Aeromodeller was fully consistent with the earlier Radio Modeller article.

Taking the above evidence as a whole, it seems to us that it was most likely in 1965—a year after the introduction of the .099S—that Fuji came up with what perhaps may legitimately be considered the definitive Fuji twin-stack model—the fifteenth model Fuji .099 and the second post-Menasco Fuji twin-stack variant.

This excellent and interesting little engine represented a complete re-think of the basic Fuji .099 twin-stack design. Bore and stroke remained unchanged and the revised crankcase retained the stronger conventional mounting lugs which had been introduced on the previous twin-stack model. However, a significant change was the elimination of the former bell-mouth venturi intake in favour of a cylindrical stub venturi which could accept either a conventional venturi insert or an R/C throttle. This was clearly done as a standardization measure to bring the new twin-stack model into step with the companion 099-S, which featured an identical venturi set-up. Another change was the disappearance of the odd protrusion beneath the main bearing which had been a feature of the previous model. This was replaced by a conventional gusset as seen on earlier variants.

The only other external change to the case was the switching of the identification markings to opposite sides from their previous location—the left side of the case (facing forward) now bore the "Fuji 099" designation while the "1.6 cc" notation appeared on the right hand side. One wonders why they felt the need to do this ...

The most significant changes centred around the cylinder assembly and the scavenging system. Gone was the screw-in blind-bored cylinder with integral fins and separate staked-on alloy head. The cylinder was now of conventional form, with a thick-walled plain steel open-ended cylindrical liner dropping into the case and resting on a narrow shelf formed in the case at the base of the cylinder. The cylinder was now topped by a plain disc of aluminium having the same outer diameter as the cylinder. This disc served as the cylinder head and was drilled and tapped at its centre for the glow-plug.

Both cylinder and head were retained by a screw-on cast alloy cylinder jacket with integrally-cast cooling fins which was externally threaded at its base and engaged with an internally-threaded section of the upper crankcase above the exhaust ports. The system was in fact the same as that used on a number of the earlier Davies-Charlton and ME diesel engines. The head itself was sandwiched between the top of the liner and the inside face of the jacket, the top of which was bored out sufficiently to allow access to the plug mounting hole in the head. A gasket was used to seal the head to the top of the cylinder liner.

The elimination of the former staked-on head was a very good move in terms of the engine's structural integrity. However, it offered no relief from the problem of alignment of the head with the piston. The use of a plain disc head secured by a screw-on jacket meant that the annular positioning of the head when tightened down could not be guaranteed. This being the case, there was no way that an upstanding baffle like that employed in the .099S could be used.

But this wasn't seen as a problem! It's clear that the Fuji designer had fond recollections of the porting arrangements which had been applied to the 1952-55 Silver Arrow .29 cuin model mentioned in Chapter 3. He decided to utilize a similar porting set-up in the new .099 model. However, he also wanted to retain the brand-recognition power of the trade-mark Fuji "twin-stack" arrangement which in previous years had set the Fuji .099 apart from its competition in a visual sense at least and had by now become something of a "cult" among sport fliers.

The solution was to make the cylinder porting functionally identical to that which had first appeared on the Silver Arrow model but turn the cylinder through 90 degrees to bring the bypass to the front of the barrel. The two very wide exhaust ports then discharged directly into the two stacks, albeit at a shallow angle towards the rear. The result was a more or less conventional loop-scavenged engine with the cylinder set at 90 degrees to the usual orientation, a fact which was pretty effectively camouflaged by the retention of the twin stacks! Shades of the old Torpedo Special, in fact!

To deal with the limitation that an upstanding piston baffle could not be used, the designer reverted once again to the step in the piston crown which had been employed in the Silver Arrow model. In the case of the new .099, the relatively narrow transfer passages allowed this step to be milled as a straight segment across the piston crown rather than following the piston wall in annular fashion. It is an inescapable fact that this results in a combustion chamber shape at top dead centre which is less than ideal—a "pocket" is created which tends to concentrate gas to the bypass side away from the ignition source. This in turn will tend to delay the full involvement of the charge in the combustion process.

The presence of the crankweb and induction system at the front of the case created impediments to the provision of a bypass bulge like that which had been used on the Silver Arrow model. Accordingly, a leaf was taken out of Enya's book and the cylinder wall was made very thick so that twin side-by-side bypass passages could be milled directly into the cylinder wall at the front. This approach had of course already been used in the Fuji .099S (Model 099-14) described in the previous section.

But this didn't completely solve all of the problems, and compromises had to be accepted. In order to locate the twin exhaust ports somewhere near correctly to line up with the twin stacks, it was necessary for the twin bypass passages to be made relatively narrow. This might well be expected to have an adverse effect upon transfer gas flow efficiency at higher speeds, although the consequent high transfer gas velocities at low speeds might reasonably be expected to aid starting.

The arrangement also resulted in the entry to the bypass passages at their lower ends being significantly obscured by the piston skirt and crank web at bottom dead centre. A cut-away in the lower piston skirt at the front would have helped here, but it wasn't provided, likely for cost reasons. The addition of such a cutaway, if done correctly, is a very worthwhile performance modification to one of these engines, as I know from personal experience. It both improves gas transfer efficiency and lightens the piston.

None of these arguments were sufficient to deter the Fuji designer from putting this arrangement into practise, and there is no doubt that it works quite well enough for all normal purposes. The result was a really distinctive-looking little engine which was far sturdier than its twin-stack predecessors and had if anything a slightly better performance. Weight remained well under control too, measuring up at 3.5 ounces all inclusive with tank. This was some 0.3 ounces less than the companion 099S model without a tank.

The manufacturers claimed an output of 0.17 BHP at 13,000 rpm—slightly higher than their claim for the old radial-ported model. Based on my own experience, this claim seems highly optimistic for an unmodified unit, but the engines certainly run quite well enough for the sport-flying purposes for which they were intended. They are also remarkably sturdy as well as being very well made. And in my possibly biased view, they're among the prettiest and most individualistic little .099 engines ever produced—the red tanks, green venturis, tumbled cases and twin stacks make a really eye-catching combination!

A sign of the times was the fact that by now Fuji, like everyone else, was looking at the R/C field as the emerging imperative marketplace in which to compete and clearly planned from the outset to sell an R/C version of their new model. We noted earlier that to facilitate this, the new crankcase followed the lead of the .099S by incorporating a stub venturi into which either an open venturi or a very basic butterfly-type R/C carburettor could be fitted. The venturis supplied with the un-throttled models were of high-strength plastic, bright green being the predominant colour. It appears that the original metal venturi used in the companion .099S (model 099-14) was changed to the same plastic item concurrently with the introduction of the revised twin-stack model.

From the outset, an R/C version of this model was offered alongside the control line/free flight unit. The R/C carburettor initially supplied with these engines was extremely rudimentary, consisting of a simple butterfly restrictor located co-axially with the spraybar. Air bleed was fixed, being provided simply by a hole drilled through the centre of the butterfly. The throttle worked well enough for sport-flying purposes, although it could certainly have been improved upon. Again, cost was doubtless a factor here—Fuji's market position remained totally dependent upon their being able to undercut their competitors in terms of price. Later examples featured a barrel restrictor located co-axially with the fuel jet, but the unit remained rather basic by then-emergent standards.

The R/C version of the twin-stack Fuji .099 model 099-15 was briefly discussed in the previously-noted article which appeared in the British magazine Radio Modeller in December 1966 as one of a lengthy and very informative series of articles on R/C engines then on the British market. Unfortunately, no performance figures were given.

It appears that the engines were serial-numbered sequentially as they came off the line, regardless of whether they were R/C or control-line models. Serial numbers of both variants are freely intermingled in our joint experience. My own lowest serial-numbered example of this very neat little engine bears the number 9568. This engine has lost its box, but my next higher numbered example (NIB engine s/n 20111) was supplied in the two-tone green box with what must be a left-over leaflet still showing the former model. It appears that they continued to use the old leaflet as long as stocks remained, regardless of whether or not it matched the engine with which it was supplied!

My other LNIB example of this model (s/n 20388—only 277 units later) is an R/C unit which was supplied in yet another revised box along with a revised leaflet showing the 099-15 model. The new box was somewhat less sturdy than its two-tone green predecessor and was lettered in a busier and rather less elegant "checkerboard" style in red and black over a white background. It appears from the evidence of the two examples noted above that they changed the box at more or less the same time as when they ran out of the old outdated leaflets. Our present best guess is that the new box style was introduced in late 1966, perhaps a year or so after the introduction of the revised twin-stack model. Admittedly there may well have been a period of overlap between the two box styles.

This red and white "checkerboard" box style was to last until the early 1970's, when a further change took place to a plain red box with white lettering. The checkerboard box marked the final abandonment of the "winged Fuji" trade-mark which had appeared on the boxes since the beginning—the new trade-mark on the plain red boxes was simply the word "Fuji" inside an oval border.

The revised leaflet supplied with engine number 20388 shows that the other engines in the range had been further revised in the interim period. By this time both the 29 and 35 models had been significantly altered from their 1957 configuration and were now little more than Enya clones. The radial-port 19 had outlasted the 29 in its original form, but it too had now given way to an Enya-styled model, and the 15-III continued in its Enya-inspired form as well. The range was fast losing its design originality ...only the twin-stack .099 model 099-15 and the radially-ported .049/.061 models retained their Fuji design distinctiveness.

Following the introduction of the revised twin-stack model described above, the .099S (model 099-14) continued to appear in Fuji leaflets alongside its twin-stack companion. Both models were mentioned in the December 1966 article in Radio Modeller to which reference has already been made. It may be queried why Fuji would continue to offer two very distinct models in the same displacement category. The answer is almost certainly that the twin-stack .099 had established itself as a symbol of Fuji's independence in terms of their design approach, and the eventual abandonment of that approach was seen by many as a matter for regret, albeit quite understandable in terms of economic survival.

Fuji demonstrated their agreement with this assessment by showing a marked reluctance to let their old twin-stack icon pass from the scene! And it seems that a fair number of buyers agreed with them, myself among them! They continued to produce and list the revised twin-stack model alongside the .099S for some years. I have a feeling that this was as much due to sentiment as hard business acumen ... but having said that, we are aware of one of the revised twin-stack 099-15 models bearing the serial number 82412—quite a production record!

A word of warning to those who may be tempted to see what's inside one of these motors—their re-assembly is a little tricky! When fully tightened, the ports have to line up correctly, and achieving this requires quite a bit of hit-and-miss fitting and tightening because there is no positive annular location of the cylinder in the case. Best to leave these engines well alone unless circumstances arise in which disassembly is unavoidable. And if that happens, please use the proper pin spanner and avoid marring the head!

16th Model, Fuji .099: the Fuji 099J-II (Model 099-16)

By around 1970 the process of "modernization" of the Fuji line-up was nearing its logical conclusion—the range had almost achieved a state of total conformity with prevailing model engine design thinking. Work was underway to replace the loop-scavenged 099-S with an updated model to be designated the 099S-II (see following section). Fuji models in other displacement categories were also being updated during this period, although the now-venerable .049 model was still soldiering on at this time. While the performance of the engines doubtless benefited from these changes, there's no question that the range had lost most of its interest and individuality from an engine design standpoint.

It seems from all of this activity that the Fuji range had finally found its place in the world model engine marketplace. The engines were now being manufactured by Tannan Industrial (see Chapter 2), in whose capable hands the engines were quite comparable in terms of quality with their more familiar name-brand rivals like Enya and O.S. In addition, the performance gap that had formerly existed had become far narrower. These factors were becoming known to more and more modellers (like myself) all the time, the consequence being that the Fuji engines were increasingly seen as legitimate (and lower cost) alternatives to their better-known competitors. The downside was that the line-up had more or less completely lost its design originality and had become in effect simply an alternative source of generally very similar engines to those on offer from other makers.

But we did say "more or less"! There still remained one bastion of Fuji's former design originality, and one with which the Fuji designers clearly remained reluctant to part. This was the twin-stack .099 model which had by now become something of a "cult" engine in world modelling circles, more because of its refreshingly different design than for any practical advantages which it possessed. People bought them in substantial numbers simply because they "liked them" and they were cheap!

The advent of the significantly improved loop-scavenged Fuji 099S-II (to be described in the next section) could have been seen by Fuji as the perfect opportunity to finally lay their twin-stack icon to rest. But even at this juncture, they were evidently unwilling to take this step. Instead, they decided to have one more go at updating the old twin-stack model to keep it as nearly in step with its competitors as possible. The result was the final Fuji .099 twin-stack model of them all—the Fuji 099J-II. This fits into our numbering scheme as Model 099-16, reflecting the fact that it was the sixteenth model in the Fuji .099 series.

There was not a great deal that could be done with the lower part of this model—we have already discussed the limitations imposed by the twin-stack design. The main areas where improvements must have appeared possible were in the transfer and combustion chamber arrangements.

We noted that the used of a button head with screw-in cooling jacket precluded the use of a baffle piston in the 099-10 twin-stack variant because the position of the head when tightened up could not be guaranteed. The design revisions which were now developed were predicated upon the use of a cylinder head which could be assembled in a consistent orientation relative to the piston. This required the use of a bolt-on head similar to that now used on all of the other models in the Fuji range.

So a revised main casting was developed which included integrally-cast cooling fins above the exhaust stacks, replacing the former screw-in cooling jacket. This new upper casting incorporated provision for a conventional drop-in liner to be held in place by a finned bolt-on head attached with four screws. The liner was essentially unchanged from that used in the previous model, as were the porting arrangements. Although the use of a bolt-on head theoretically made the use of a baffle piston possible, advantage was not taken of this option—the piston too was essentially unchanged from that of the earlier twin-stack variant, as were the crankshaft and induction arrangements.

The twin stacks themselves were altered slightly in this model. They now had rounded ends rather than the square configuration formerly used. This was presumably done to facilitate the use of a muffler system.

By this time, the Fuji box style had changed to a solid red label with white lettering. The revised model seems to have been aimed at the flying scale model market since it was supplied with a rather oversized spinner and a relatively bulky clamp-on twin exhaust muffler system, while the former back tank was omitted. It came in both R/C and C/L versions. Bore and stroke remained unaltered, as did the stated weight. The maker's performance claim of 0.17 BHP at 13,000 rpm also remained the same. Given the fact that the engine was unchanged from its predecessor in functional terms, this is scarcely surprising.

For some unexplained reason, these engines appear to be rather uncommon today despite the indications from known serial numbers that quite a few were made. The range of presently-known numbers goes from a low of 29768 to a high of 68755.

The distribution of this model appears to have been a bit inconsistent—although Fuji engines were quite popular in Canada at this time and were widely sold and used, I never saw one of these models on sale here at any time. I was a regular Fuji user at the time and would certainly have bought one if I had run across any for sale—I was a huge twin-stack fan!

End of the Twin-stacks: the Fuji .099S-II (Model 099-17)

At some point around 1970, or soon thereafter, the loop-scavenged .099S was supplanted by the "modernized" and completely conventional .099S-II (Model 099-17). This probably took place at around the same time as the introduction of the .099J-II twin-stack Model 099-16 just described.

The .099S-II was very much a slightly re-styled Enya clone which proved to be the very last of the "classic" Fuji .099 models. The manufacturers claimed a slightly less fanciful 0.22 BHP @ 14,000 rpm for this model. My own experience confirms that it is definitely more powerful than the 099S, and probably comes far closer to meeting the maker's performance claim than its predecessor had done! The illustrated example bears the serial number 35067. Clearly quite a few of these were made.

This proved to be the kiss of death as far as the classic Fuji .099's were concerned! Within a year or so of the introduction of this model, the twin-stack .099 was history and the company was moving out of the "classic" era with its Inner Bypass Schnuerle (IBS) and ABC models. I have a leaflet from an 099S-II bought new in the mid 1970's, and there's no mention of any twin-stack model. I for one noted its passing with regret, and I'm really glad that I still have my own examples of those very distinctive little engines with which to console myself...

In the mid 1970's the 099S-II was joined by the .099SR, which moved the series out of the "classic" era by using Fuji's Inner Bypass Schnuerle (IBS) porting system and produced a claimed 0.28 BHP at 15,000 rpm. The .099S-II soldiered on for a year or two as a "budget" alternative alongside its updated and far more powerful brother and then faded quietly from the scene. The "classic" Fuji .099 series had finally reached the end of the road, seventeen models and a quarter century later ...

Well, there it is—everything that we've been able to discover about the interesting and original little "classic" Fuji .099 engines from Tokyo. Hope you found something of interest here!