RC Plane Review

Review of the Hurricane RC Plane from R-C.UK

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As I had already sampled the delights of flying one of R-C.UK’s prototype RC Hurricanes, I was eager to get cracking on an actual kit of my own. First procedure was to remove all ply and balsa formers methodically from the die-cut sheets. Only a couple of the ply formers had to be persuaded out, a knife being used, taking care not to splinter the coarse grain. The weight of the balsa and ply parts was 31b. 10oz. The standard of the wood parts was pretty consistent, only one of the leading edge and one of the trailing edge strips requiring replacement. The ABS plastic mouldings retained a standard thickness, only the main radiator seeming unduly thin. However, flying sessions have since shown that, once securely bonded in position, this withstands belly landings adequately. The total weight of all the mouldings was 14oz., while the engine mount and other hard-ware scaled 8oz.

Hurricane RC Plane

Hurricane RC Plane

The two obechi veneered foam wings weighed 11b. 15oz., and appeared very consistent, without any twists. This was my first attempt at using foam wings, so I was rather apprehensive but, in the event, my worries were unfounded as joining went without a hitch, the roots lining up well. As suggested in the instructions, I drilled lightening holes in all the formers aft of the cockpit, as well as drilling out parts of the crutch in this area. A help at this point would have been a sheet giving the full-size shape of the crutch. A point worth noting at this stage is that, if a scale section tail is built, the fuselage has to be widened to accept the greater width of the scale fin and rudder. When fitting the sheeting on the lower fuselage sides, I cut the balsa to the exact length of the sheeted section. With hindsight, it would have been a little better to allow a slight overlap at the rear former position, to increase the gluing area of the stringers into the sheet. During the upper fuselage construction, while fitting the stringers aft of the canopy, I felt that they just didn’t have the right shape. I therefore fitted packing pieces be-tween the appropriate formers and stringers. The upper nose sheeting was rather soft, which made for easy shaping before gluing into position. However, after assembly it did seem a little fragile around this area, so I strengthened it with an application of thin glass-fibre cloth and epoxy resin to the inside. After rubbing down and sealing, I covered the rear fuselage with nylon, and the front with heavy weight tissue. The tail assembly parts were glued together next, and weighed to establish any weight saved by the built-up tail section as against the solid version. Finally sanded, they weighed 8oz.’ a saving of 2oz. at the tail end. A concealed control horn was fitted to help the scale appearance, and the fitting of this required the cutting of a hole in the crutch below the tailplane position.

Hurricane RC Plane tailplane

The tail surfaces were covered with heavyweight tissue before epoxying them to the fuselage. Wing construction was simplicity itself, the only worry being the large wheel well cavities. These came very close to the top of the wing at their deepest point, and caused me concern about the wings withstanding a hard landing. To strengthen these areas I poured Cascamite into the gap between the plywood mounting plates and the foam. (With hindsight I would suggest 5-minute epoxy rather than Cascamite, which tended to break up with use.) ‘The advised installation details for the retract units were religiously followed, using the sponge rubber seatings. The ABS mouldings, with pa-tience, assembled well. As these did not include tailplane and fin fairings, I used thin card cut to shape and contact-glued in place.

Radio installation

Having worries about tail heaviness, I fitted the radio as far forward as possible. The servos were sited below the fuel tank, with the power pack between them and the engine bulkhead. A plywood plate sup-ported the switch, and a bellcrank was used to transmit the switch movement through to a piece of 16g. wire protruding through the fuselage top, impersonating the forward gunsight. Rudder control was achieved by the use of a tube and cable linkage that gave a scale appearance to the rudder horn. The receiver was fitted on a balsa shelf immediately behind the wing dowel bulkhead, while the wing servos were fitted—retract servo above and slightly forward of the aileron servo—into the centre section.

Hurricane rc radio installation

Hurricane rc radio installation

Finishing

After rubbing down and sealing, two cellulose colour coats were sprayed on, without using under-coat. Duck Egg Blue on the under-surfaces and Earth on the upper-surfaces. The Green was sprayed freehand to match the camouflage decor of the original, a matting agent being used throughout. With roundels and markings applied the model was systematically panel-lined, “dir-tied up” with scuffing marks added, and then sprayed with one coat of Furniglass `Harclset’ followed by one coat of K&B satin clear. The model complete with gear installed ready for flying, weighed in at 10lb. lloz.

Flying

At this weight the e.g. carne out at approximately 5 inch back from the leading edge. Deciding not to add any more weight, and the H.B.61 installed and running, the usual control surface checks were made. No problems arose, so the maiden flight was started. The model virtually flew itself off the runway, and needed very little correction on trim.

I could not kill a slight climbing tendency even with full down-trim, and the model tended to be touchy on up-elevator. Aileron response, however, was good and not at all over-sensitive. The undercarriage was retracted and seemed to allow the 14 x 6 prop. to pull the big Hurricane around the sky a little faster, although the air-speed still seemed somewhat slow, the turns sagging a little. Attempting a landing, the motor quit as I approached and, as the round-out came, the touchiness on the elevator really showed. The model ballooned and dropped a wing about two feet from the runway, resulting in the undercarriage being wrenched out as the Hurricane dropped onto its nose. Back home 31oz. (in the form of Ain. thick brass plates) was fitted at the back of the engine-bearer fixing nuts, bringing the c.g. to a new position 5in. from the leading edge. Further flights were now made, this time acrobatic manoeuvres being performed. The rolls, stall turns and reversals were easy but the loops showed an odd tendency for the model to ‘float’ momentarily in the inverted position, especially when the speed was allowed to drop off. These flights have shown that a 12 x 6 prop. gives a better performance in flying speed, in both straight flight and through manoeuvres. Adding a further 5oz. of lead to the nose brought the c.g. to its recommended position 4iin. back from the leading edge, and this cured any tendency to tip stall at the bottom of a tight loop and when ballooning the round-out.

Hurricane rc plane flying

Hurricane rc plane flying

Summary

You can buy the Hurricane RC Planes from R-C.UK, My thanks to the company for loaning us the plane for this review. This large Hurricane is well worth the constructional effort, and has certainly given me hours of most enjoyable flying. It attracts admirers everywhere it’s flown, and—above all—really looks the part in the air. I look forward to many more hours of flying, enjoying the acrobatic manoeuvres and low passes characteristic of the famous prototype.

RC Plane Engines

Nitro RC Plane Engines

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Several new Super-Tigre engines are being released for 2015, including three small ones: the X.11 R/C, the X.21-RE and the X.25 RIG.

Super-Tigre engines

Super-Tigre engines

 

All three are shaft rotary valve, Schnuerle scavenged engines with one-piece main castings and ST Mag automix carburet-tors. The X.11, the first new small ST engine for more than twenty years, is being offered in two versions, the X.11- PB with bronze brushed main bearing and the X.11-BB which has a single ball-bearing. Bore and stroke measurements are 115 X 12.5mm, giving a swept volume of 1.789cc or .1092cu.in. No performance figures are available at present. The X.21-RE is a new 3.5cc RIC car engine with rear exhaust. Like the standard side exhaust X.21, it has an ABC piston cylinder-liner assembly but, rare in a modern engine, uses a stroke/bore ratio above unity, the stroke being increased to 17mm, while the bore is reduced to 16mm for a swept volume of 3.418cc or 0.2086cu.in. The engine is claimed to produce (fuel unspecified) just over 1.0bhp at 25,500 rpm. The X.25 R/C, seemingly a bored and; or stroked version of the standard X.21; the catalogue illustration is actually of an X.21 and no bore and stroke measurements are quoted, but the crank-shaft part numbers are the same so we would guess that the cylinder bore has been increased from 16.6 to 18.0mm, the same dimensions as for the O.S. 25FSR, which would give a displacement of 4.072cc or 0.2486cu.in. One structural difference between the X.21 and X.25 is that the latter has a conventional ringed piston running in a steel cylinder liner, instead of the X.21’s ABC set-up. Super-Tiger X.21

Our photos show a current standard X.21 in R/C aircraft form. This motor is also available, from World Engines, in three other models, i.e. in standard racing trim with a 6nun (28sq.mm) peripheral jet venturi, as an RIG car engine, or as an RIC marine engine. Like other Series-X Super-Tigres, the X.21 is essentially a high performance unit. It features the much-copied ABC (ringless aluminium piston running in brass cylinder-liner with chromed bore) set-up origin-ated by Super-Tigre designer-manufacturer jaures Garofali, a Schnuerle scavenging system and, of course, twin ball bearings supporting the crankshaft. The shaft has a 12mm main journal, a 7mm front journal, an 8mm i.d. gas passage and a large (14mm long) valve port. Counterbalancing is by means of unsealed peripheral crank disc slots. The main casting is of sturdy proportions, with a well braced front end and an offset intake to promote a tangential gas flow through the rotary-valve. The cylinder liner has a single, unbridged, exhaust port and each of the main transfer ports flanking it incorporates an angled vane to direct gas to the opposite side of the cylinder, where it is joined by the upward flow from a steeply inclined third port. The ringless piston is machined from aluminium alloy bar and the machined conrod, bronze bushed at the lower end, is coupled to the piston by a 4rnm tubular gudgeon-pin retained by wire circlips. The cylinder head has the popular bowl-and-squishband combustion chamber shape and is secured with four screws.

Super-Tigre engines strip down

Super-Tigre engines strip down

 

No gasket is fitted. The carburettor is a standard ST Mag type with adjustable automatic mixture control, a 7.5mm choke and standard 4mm spraybar. The standard silencer (not supplied) for the engine is the S–15C expansion chamber with 6.2mm i.d. (30sq.mm area) outlet and a volume of 26 millilitres. Like all Super-Tigres, this is a well engineered motor with finely finished working parts made from high grade materials. The engine has a bore and stroke of 16.6 x 16.0mm, giving a swept volume of 3.463cc or 0.2113cu.in. The manufacturer’s claimed power output (fuel un-specified) is 0.75bhp at 25,000rpm. Checked weight of the example examined was 237g (8.36oz.) or 278g (9.80oz.) with silencer. Super-Tigre 60 range for 1979 With the recent introduction of the Super-Tigre X.60 front induction R/C engines, it was supposed that we would now see the withdrawal of the last of the G.60 series, which date back to 1966. However, this has not been the case: the latest Super-Tigre catalogue still lists the front rotary valve G.60 Blue-Head engine. Moreover, that old-faithful, the ST 60, the original model of which goes back to 1963, is continued in a further improved version. Thus, the Super-Tigre 10cc RIC engine range now consists of four models and, for the record, these are, briefly, as follows : Super-Tigre ST.60 Based on the lighter one-piece ST casting. Conventional crossflow scavenging with ringed deflector piston and steel cylinder liner. When tested in 1970 form (Radio Modeller, October 1970 issue) it produced a gross output of 0.95bhp at 12,600rpm on 5 percent nitromethane fuel but was considered to be unduly restricted by its Mag-II carburettor with only 20sq.nun choke area. The newest model is fitted with a Mag-V carburettor having a 9mm i.d. choke and an effective choke area of 30sq.mm. The manufacturer now claims an output of 1.38bhp at 13,800rpm. Lighter than most .60s, the ST .60 weighs approximately 14oz. Super-Tigre G.60B1-1-ABC-RING With this some-what unwieldy title, this model is basically the G.60 ABC engine that was featured in our March 1977 Radio Modeller Engine Test report, but with a ringed piston. The chromed brass cylinder liner is retained (hence the continuation of the ABC suffix) but this is combined with a ringed piston as in the X.40FI, X.45FI and X.60FI. The ringed ABC set-up, another Super-Tigre innovation, is considered to be more serviceable for everyday use than the ringless aluminium piston which, if one is talking in terms of useful life, is so dependent on its being operated, at all times, under clean conditions. As with the ringless ABC engine, however, each piston and liner is assembled as a matched pair and replacements are only available as such. The cylinder porting is Garofali’s own, based on a modification of the PDP (Perry) system, but used in conjunction with a deflector-less piston to give a gas flow similar to that of Schnuerle scavenging. On test, the 1977 engine produced a gross output of 1.60bhp at 16,500rpm on 5 percent nitro which, as was pointed out at the time, was fully competitive with current Schnuerle type engines. The Super-Tigre factory is now claiming 1.70bhp at 16,000rpm for this newest version. The engine weighs 16.7oz. less silencer, 19.6 with the S.60 silencer fitted to it or 20.3oz. with the newer, larger volume M.60 expansion chamber. Super-TigreX.60F1-SL andX.60F1-SP These new X-series engines have the same bore and stroke as the ST.60 and G.60 models (24 x 22mm giving a swept volume of 9.953cc or 0.6073cu.in.), but have Schnuerle scavenging and offer the choice of side exhaust (X.60FI-SL) or rear exhaust (X.60FI-SP) versions. Other features in common with the latest G.60 include the use of a ringed ABC piston; liner assembly (all these engines use the same piston-ring, conrod and gudgeon-pin) and the Mag-V carburettor with 9mm choke and flattened spraybar to increase effective area to 42sq.mm. Like the G.60, the X.60s have a 15rnm o.d. crankshaft with an 1 lmm i.d. gas passage and the bearings, a 7 x 19mm front and 15 x 32mm rear, are the same in all three models. As one might expect, the SL and SP versions of the X.60 also share a number of other parts, including the crankshaft, front housing, back-plate and cylinder-head. There is no significant difference in the performance of the two X.60 models. The factory rates the SL at 1.71bhp at 15,200rpm and the SP at 1.72bhp at 15,300rpm. These are the gross (open exhaust) figures. The side exhaust engine is supplied with a machined flange to enable it to be fitted with the M.60 expansion chamber silencer. The rear exhaust motor is primarily intended for those who wish to use the ST tuned length silencer. Checked engine weights were 17.5oz. for the rear exhaust model and 17.3oz. for the side exhaust engine, the latter figure being increased to 21.30oz. when the M.60 silencer is added. Tuned pipe weights for the SP and SL are 7.6oz. and 9.8oz. respectively. Power v. Noise—again Just a year ago (in the May 1978 issue) R.M. was taken to task by a reader for publishing a test report on a powerful and (admittedly) noisy engine, thereby giving encouragement, we were told to, quote, “the top-comp-with-its” and “the noise vandals—engine The Super-Tigre X.60F1-SP, introduced last autumn, was the Italian factory’s first Schnuerle scavanged .60 R/C motor.

Schnuerle scavanged .60

manufacturers and their employers, the competition modellers . . .” who, allegedly, were responsible for the widespread loss of flying fields. So, while we did not really go along with the notion that the competition flyers were the only ones to blame for the flying site problem, we did, subsequently, try (in the January issue) to put the case for inherently quieter engines—four-strokes, Wankels and slower-revving, better silenced two-strokes. It was pointed out, for the benefit of newcomers, that a 1.5 to 2.0bhp engine is not essential and that perfectly good aerobatics can be flown on less than half the power of a modern Schnuerle scavenged .60 R/C motor and we quoted the example of people like Chris Olsen, Bob Dunham and Frank Van den Bergh who, in the past, flew championship winning performances on engines developing between 0.55 and 0.70bhp. Did we succeed in taking the heat out of the situation? Not entirely. Our defence of the quiet life prompted just one reader to reply : the one who happens to be, cur-rently, the top “top-comp-with-it” of all, namely, David. Hardaker, present U.K. National R/C aerobatics cham-pion. His letter was long, so we will omit the preamble and deal with the central issue, which is David’s argu-ment in favour of power and plenty of it. He writes .. . “There is no way that plenty of power can be an em-barrassment—only, I agree, through noise, but if power is in hand, one can afford some sacrifice towards more effective silencing. “Bob Dunham and those pioneers of his day, flew aerobatics with less power on lighter wing loadings simply because that power was as much as they could get and there was no other choice. Neither did they use silencers. “Before saying that perfectly good aerobatics are possible on less than half the power of today’s good 60s, you must take into account the present FAX schedule, a much more complex task than 12 or 15 years ago. I reckon if anyone could do today’s schedule with, say, an Astro-Hog using one of yesterday’s 45s, then that same person could walk on water. cc . . . The vast majority of British or any other aerobatic flyers use the current types of model purely because of their superior handling qualities compared to smaller or lower powered models and as such, know how to appreciate them. “However, I agree that this variety of model can be a misfit on some flying sites, purely because of nearby populated areas, but surely this is where discretion should play its part. “If progress must be made, then let’s follow full-size practice and go to the more compact Aresti type schedule where manoeuvres flow into each other and fly it with near-scale aerobatic types using larger than 60 size motors if lower revs are required.” Right. A good argument in favour of the status quo so far as the seasoned competition aerobatics flyer is concerned. But what has to be hammered home is that FAI class competition flyers comprise about one percent of the RiC fraternity. What we should all be doing is looking for ways and means of influencing development along lines that will be of benefit to the other 99 percent and this means, whether we like it or not, making model RIC flying more acceptable to the general public on whose goodwill we all, ultimately, have to depend. The alter-native is for everyone to do what an awful lot have done already: give up power models in favour of gliders. Let us look a little more closely at one or two of David Hardaker’s arguments. The latter part of paragraph one sounds reasonable, but all the evidence, so far, supports the view that competition modellers, in general, do not voluntarily sacrifice power in the interests of better silencing.

nitro rc plane silencer

nitro rc plane silencer

We saw this in the adoption (when silencers became obligatory) of totally ineffective open-front “non-silencers”. More recently, tuned pipes have found their way onto acrobatic models, admittedly with some benefit on noise levels but, undoubtedly, chosen mainly as a means of maintaining or even increasing power output. On to paragraph two and the “pioneers”. Covering many contests in those days from club to international level in reporting (and occasional judging) capacities, we were not aware of top pilots’ anxiety, at that time, to find more power. Generally, they were more concerned with polishing manoeuvres and keeping all the hardware working properly. If, in 1961 or 1962, the FAI had de-creed that the K&B 45 or the Merco 49 would henceforth be the most powerful engine eligible, the heavens would not have fallen. We can be quite sure that FAI aerobatics would have continued to thrive and to be enjoyed by its participants. The fact is that, unlike other competition classes, RiC aerobatics has remained remarkably unfettered with regulations governing model design and engine power. In other categories, the FAT has repeatedly imposed restrictions to keep performance within bounds : for example, by reducing engine capacity (e.g. down to 2.5cc in the World Championship CIL speed class), by fuel tank capacity (as in CiL team racing) and by towline length (as in towline glider). Paragraph Three: Well, now, what a way to sort the men from the boys ! But wouldn’t it be equally true to put the question the other way round and say that, with

virtually no restrictions on design, apart from a Eke engine size limit, models have become so potent that the FAI schedule has had to be made steadily more difficult simply to mop up excess performance? As for handling qualities (paragraph four) it rather depends, one sup-poses, on whether you want contests to put the emphasis on proving the suitability of the aircraft for the task before it, or on the skill of the pilot in coping with its limitations. Paragraph Five. Where available flying sites make the currently favoured high powered model a “misfit”. The snag is that the average bod who gets bitten by the aerobatics bug will undoubtedly follow the example of the expert and will want to build and fly a high perfor-mance model. It is not much good then trying to tell him that his expert class model is a “misfit” in the club environs and that “discretion should play its part . .” What he needed to be offered, in the first place, was a viable alternative. What about a nationally or inter-nationally recognised “Formula 3″ aerobatics class that would provide a quieter, slower, club or inter-club contest alternative to the present “Grand Prix” acrobatic model? Paragraph Six. Near scale acrobatic models using larger than .60 size motors and lower revs. Fair enough. A well-muffled .90 turning slowly enough to avoid excessive prop noise and, presumably, a big wing area model flying at near scale speed. Very nice. Not, how-ever, for the ordinary club flyer who already thinks modern .60s are too expensive. Again, perhaps, this is where our Club “Formula 3″ acrobatics model would come in? .40 size engine? 12 x 6 prop? 150cc expansion-chamber silencer with 40sq.mm baffled outlet? 600sq.in. wing area? Food for thought?