BO 209 Monsun

BO 209 Monsun

 

  • This review was first published in 2005. The kit is still available.

When I was starting out in ‘multi’ radio (more than just single channel), one of the more expensive and most lusted after R/C kits then available was the Graupner Monsun. Its handsome lines, big canopy, striking red scheme and pretty, spatted, trike undercarriage set it apart from the herd. In those days, about thirty-odd years ago, the kit was an expensive import and well beyond a young modeller’s pennies. I remember wryly that its typically thorough Graupner ‘optional accessory pack’ cost more than the whole model I was currently building! Over the years there have been smaller Graupner Monsuns, electric Graupner Monsuns and recently at Nuremberg 2005 they’ve even displayed a monster Monsun. I love ‘em all, though I’d stick a proper engine in that cute little ‘leccy one. Times change, and this ARTF avatar of the Monsun has been simplified and Vietnamised. When the editor said that he had a Monsun for me to review, complete with a Super Tigre .51 engine, I began to think he was a good lad after all. Although in ye olden days this was a costly kit, nowadays it’s very attractively priced at just £139. Without giving too much away at the outset of this review, after my experiences with the Monsun I concluded this price was a bargain.

BOX APPEAL
Straight from the box the model is very appealing with a nicely finished fuselage, tail and wings, a comprehensive accessory pack and a well moulded cowl. The spats are sturdy and the undercarriage fittings look up to the job. Note also that the Monsun has a steerable nose wheel, driven from the rudder servo. I don’t like plastic backplate spinners common in Vietnamese ARTFs, so I substituted a tough white nylon job. Otherwise I used all the supplied fittings, which were suitably fit for purpose.

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The standard of covering is very good and only needed a touch of the Solarfilm iron, here and there, to tighten it up. As for the illustrated instructions? These are Teutonically thorough, logical and easy to follow – and the whole model is a doddle to put together. It’s a classy product.
Since there’s so little building and very little gluing, I won’t tax you with a blow-by-blow account. Suffice it to say that everything went together as it should, with no hang-ups, cock-ups or cut corners, indeed the build time was very rapid. In fact, fitting the engine – and subsequently engaging in some cowl bashing – provided the biggest tasks you meet on the bench. This is a quality ARTF, well worthy of the Graupner name and you could certainly buy the Monsun this weekend and fly it the next.

ENGINE
Had I not been issued a Super Tigre .51 engine with the kit, I’d probably have opted for one of my existing four-stroke powerplants, primarily for aesthetic reasons. Oh, and for completeness I should tell you I was offered (and accepted) a Graupner 12 x 6” propeller.

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Fitting the Super Tigre required much cowl bashing to shoe-horn it all in. It took a lot of careful measuring, templates, cutting and sanding, and in some places, it left very little cowl intact. Even then I managed to forget to drill a tiny hole for access to the slow running mixture screw on the carburettor, which, incidentally, I had to cut out later. Since, like all modern engines, the Tigre has a fashionable large-volume silencer, it cannot be hidden and the overall effect is very visible in flight. On the positive side the sidewinder installation ensures a protruding head and, as such, a remote glow system wasn’t necessary. What’s more, engine cooling was unlikely to be a problem.

During engine installation I made doubly sure to coat the exhaust stub in Vaseline before fitting the silencer, this to allow for easy removal or tweaking. Of course the net affect of all this was to slow down the build somewhat, though since I’ve never owned or operated a Super Tigre before, I worked patiently, intrigued to see how it would all pan out.

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RADIO
The Monsun requires four-channel radio for which a standard receiver / NiCad will do nicely. You’ll need five standard servos since the ailerons require a one each. For those without computer radio this also means you’ll need to buy a ‘Y’ lead. The hatch cut-outs and covers are very neat, but the slots for the servo arms were a bit on the generous side – perhaps German clevises are very fat. A short extension lead is also useful to make connecting the wings and the receiver more convenient when assembling the model at the field. As normal, I fitted a combined Webbs charge / radio switch, but since this is a sport-scale model, I hid it inside with a simple piano wire pushrod to operate it. Coincidentally, this very switch and this same ‘workaround’ is pictured in the printed instructions. A slight departure from the normal ARTF fayre was the separate radio hatch. This is because the neat and deep scale cockpit (which comes complete with nifty detail mouldings) restricts radio space above the wings when the model is assembled. I shamelessly copied my old mate Paul Strawson’s idea and fabricated a small box out of liteply to locate the NiCad in the forward radio compartment. This is much neater than carving a block of foam or padding out the whole compartment. As per Paul’s design, I also made a liteply strap, retained by screws, to hold the NiCad in the box. This is a cunning scheme and works well. If you get it neat, it really looks like its been CNC’d!

COCKPIT
Definitely a model for cockpit-fanciers. With such a large office and crystal clear canopy, it made sense to take a little extra care. The supplied seats and cockpit interior are good and, painted up, really add zest to this important area. One curious departure was that the tape supplied for lining the canopy framework was red and not white as per box lid, or indeed, as per prototype. Perhaps it was destined for the spats. Anyway, the canopy is a superb fit on the fuselage and retained by self-tappers, though you could easily dispense with these and glue / tape it down, for scale effect. Likewise, you could paint all the visible screws that hold the canopy and cowl as I did after the test flight. Since I was unable to find a full-length pilot for the office, I made one from parts of a dead soldier, hideously grafted Frankenstein-like onto a Graupner pilot bust. Truth is, in the end I think he looked much more convincing than he deserved.

BALANCE OF POWER
The Monsun balanced slightly (and safely) nose-down at the stated position, 75mm back from the leading edge, which was very satisfying since this required no lead. The finished model with Super Tigre .51, dry, but ready to fly weighed in at exactly 6 lbs.

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FLYING THE MONSUN
After a week of poor weather, a spring Saturday morning dawned bright and clear. Unfortunately the wind was cool and stiff, proving flyable but not ideal. It was after tea before the wind abated and we could fly the her and, in order to get those all-important flying shots, noted test pilot Gareth Williams was pressed into the flying role. Fresh from comprehensively totalling his new electric model (will they never learn?) my mate Neil Shirley loaned me a fresh glow start. I’d flattened mine flying my Summit all afternoon in the near gale. Anyway, I gassed up the Super Tigre, choked her two turns and felt a nice wet bounce over compression. For luck I gave a little squirt of fuel down the venturi, clipped on the glow start, and snubbed the spinner with my Marx mini-twirler. The Super Tigre started instantly – surprising the hell out of the ragged company awaiting the maiden flight. It’s hard to define but some engines just feel right from the off, and this was one of those times. Even though it was spinning a 12 x 6 and was deliberately left slightly rich, the Tigre clearly had buckets of torque and was revving very freely indeed. Opening the throttle produced a very steady and powerful increase in revs, though it was clear that the pick-up needed a tiny tweak. After a time ground running and checking the throttle response, I made the decision to go for it. A final radio check revealed all was well. Out at the strip she revved up with only a slight hesitation and after a short ground run she fair leapt into the air. There was clearly no shortage of power – or revs!

FLY BY
Gareth took the Monsun into a brief checking out circuit (very brief!) then opened the taps. He tried loops, rolls, stalls, bunts, spins and knife-edges – all performed with no bother whatever. He then tried a low-altitude rolling circle. The Monsun behaved impeccably throughout like a true aerobat, though she did look a bit funny conspicuously over-performing her scale role. Of course, you do not buy a Monsun for its aerobatic potential, but our job is also to test the airframe, so that’s what we did. She came through all of the rough stuff with flying colours, though she wanted to fly a little faster than I would expect from scale tourer. On ‘medium speed’ straight and level fly-bys she looked a peach with her pretty ‘sit’ in the air and her elegant little spats hanging in the breeze. Cor! This is real ARTF modelling! Making her climb steeply away from us showed a very pretty plan-form too. After a good thrashing, fuel was getting low so we landed, gassed her up again and tried some other manoeuvres. Take-off was again excellent and climb-out once more was vivid. This time Gareth, being a hooligan, decided to hover the Monsun. She looked very odd and very un-scale-like hanging on the wind like a Chinese kite, but was surprisingly controllable. Honour satisfied, we set to the photography, in what proved to be the last of the good light. She does look very attractive on a low ‘Delyn Pass’ with her outside wing held slightly up – every inch a light tourer.

MY TURN
We ran out of light, so my turn at the sticks came four days later at a deserted mid-week Singing Kettle field. The Super Tigre was doing well and again started instantly. In fact, I now expected it. On this occasion I voted to taxi out to the strip as the tricycle undercarriage is so stable and well set out that the taxiing and ground handling were utterly superb. In fact, I drove her around the empty field for some minutes, like a car, just for the fun of it. Pointed into wind I opened up the throttle and she very quickly reached flying speed. For scale effect you really don’t need all that power.

TRIM HER OUT
Now, although Gareth and I fly on similar ZAP transmitters, we happen to fly on different modes, so I still had to trim the model out. Therefore this was really the Monsun’s second maiden flight. I needn’t have worried; she only required the odd tweak of up elevator and some right aileron for ‘hands off’ progress. She proved stable, yet very nimble. Loops tracked nicely and on high rates she twinkle rolled with no rudder required. The model looks delightful on low passes and on final approach it locks into the circuit in a very confidence-inspiring way.
My only other observation concerned the sink speed, which is a bit higher than I would have expected. She’s quite a slippery shape and has to be flown in under power with an idling prop’ to give a bit of drag. Otherwise, with dead stick, she comes in a little speedily. Nothing perturbing you understand, but a bit on the brisk side, marking her out as a first scale model and not a first low-winger or ‘follow-on’ trainer. In fact, she’s such a complete scale package, I’m a little surprised that Graupner haven’t fitted flaps!

THE VERDICT
A sport-scale sweetie! I adore her good looks, and Graupner quality makes her very quick and easy to build, without the usual ARTF compromises. I can’t think of a prettier ARTF currently on sale, and she knocks spots of the endless succession of CAPs, Extras, Sukhois and the like. Her performance envelope far exceeds her full-size counterpart – and should you tire of pottering about the scale circuit, you can chuck her about like a hooligan. Not suitable as first low-winger, since she is a scale model and a bit slippery, but a very rewarding model to fly. On top of that, she’s going for a bargain price. The Super Tigre power plant was a real revelation to me, and I can heartily recommend it. However, I feel she has a little too much power for this style of model, and fitting in all the ST’s knobbly bits did involve major surgery to that pretty little cowl. Had it been up to me I’d have gone for a .53 four-stroke, thereby ditching the big silencer. In fact, Graupner recommend O.S. engines, and the model is designed for the O.S. .46 FX (uprated now to the AX). However, mark my words, these new Super Tigres are excellent equipment, and on my experiences so far, I would recommend researching the range. They sell at a very keen price too, and have exemplary after-sales support. In fact, I’m so impressed with this ST .51, I’m going to try it in an out-and-out aerobatic sports model as soon as I can.

DATAFILE

Name: Bolkow Bo-209 Monsun
Model type: Semi-scale light / tourer
Manufactured by: Graupner
RRP: £155 (Feb 2010)
Wingspan: 1580mm (62'')
Fuselage length: 1040mm (41'')
Wing area: 34.6dm2 (536 sq. in.)
All-up weight: 6 lb
Wing loading: 26oz / sq. ft.
Rec’d engine range: .46cu. in. two-stroke or .53cu. in. four-stroke
Engine used: Super Tigre .51

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