A nimble, low-powered aerobatic design from the 1960s with superb visibility and wich is particularly inexpensive to operate, since it can be left out in the open and operated economically on a PFA Permit. "The ideal private or group aeroplane", says Bob Grimstead.
Tommy Sopwith did it first with his Grat War Camel, reasoning that if he kept the heavy bits of an aeroplane (engine, pilot and fuel tank) close together while minimising both weigth and external dimensions he would achieve maximum manoevrability. So it comes as no surprise that the equally-gifted modern Swedish aeronautical engineer, Björn "Andy" Andreasson, should choose the same configuration when he made himself a little 75 horsepower homebuilt two-seat personal plane.
As well as, a nimble handling, "Andy" Andreasson obviously also valued good visibility, so he gave his Junior´s shoulder-mounted wings a couple of degrees of forward sweep, putting the occupants ahead of the leading edge at its root for a panoramic view, but in line with its mid-span average to keep the centre of gravity near the centre of pressure. Thisconceptually simple (but structurally rather more difficult) layout endows the best of all words: view upwards, downwards and all around while allowing loading flexibility.
Twenty eight years ago, before I became completely addicted to aviation, I knew none of this. My indulgent parents, aware that their young son was becoming hooked on flying, took me to the first Biggin Hill Air Fair. I still have the photos, taken that day, worn and faded self-developed black-and-white snaps from my Kodak Instamatic of the straight-tailed Riley Turbo Rocket 310, the Fournier RF-3 motorglider subsequently developed into the graceful RF-4 used by the Skyhawks display team, the Beagle Basset and stillborn 218, England´s first Cherokee, the Tiger Club´s elegant and exiting aerobatic racer Ballerina, and Wing Commander Wallis´ remarkable autogiros.
But the photo that got most tattered - the one of the aeroplane that made the gratest impression - is a potrait of a young man and his family standing by the aircraft he felt was made for him. It is a pretty, if slightly boxy, aerobatic two-seater with a big panoramic bubble canopy, neat nose-wheel undercarriage, novel catapult-shaped double control stick and the economical 100-horsepower Rolls Royce O-200 engine.
This was the Bölkow Junior, a licence-produced higher-powered version of Andreasson´s homebuilt, and I knew it was the plane for me. I read about it, wondered about it, dreamed about it and looked forward to saving up for one. So what happened? Well, cicumstances changed, I succeeded in getting my longed-for aviation career; but family life imposed, my fortunes waxed and than waned again, and by the time I could justify my own aeroplane I could only afford the cheapest; so, somewhere along the line, the little Bölkow Junior got bypassed. Not forgotten, just relegated to the might-have-been.
Then, one day at work, strolling back alongthe aisle of my Jumbo for a cub of coffee, a a passenger stood and said "Remember me? John Webb from the Tiger Club, how are things?" Back on the flight deck in animated conversation he let slip his part-ownership of no less a maschine than that which still intrigued the small boy within me. Before he knew it he had been coerced (with little reluctance) into letting me fly with him.
Meeting again in Popham´s friendly clubhouse John told me something of the type´s history and, being a professional engineer, wayedlyrical on ist ligth, uncomplicated yet efficient structure. Andreasson had worked for Convair in San Diego on their fourengined jetliners, at one time the fastes in the sky, and he introduced his original 75 hp BA-7 Junior to the world at the 1958 EAA convention. After accepting a post as chief designer at Malmö Flight Industri (MFI) in Sweden he brought it to Europe for the 1961 Paris Airshow, and MFI undertook limited produktion of 28 Juniors. In 1963 the type´s manufacture was taken over by Bölkow in Germany with a licence to build 200 100-horsepower, fixed-fin derivatives. They introduced the improved ´B´model in May 1964 with electric flaps, stronger nose-wheel and optional one-foot wingtip extensions. This was superseeded in 1966 by the ´C´of series III model with 4 inch longer cockpit, increased fuel tankage and greater maximum weight. John´s is a series III 208 C.
The short and boxy Bölkow looks (and is) basic - almost plain.
Its simple red-and-white colour scheme does nothing to disguise the homely lines and the incongruity of rounded cowlings and bubble canopy blending oddly into the slab-sided fuselage; but this simplicity of shape and construction is a mark of a really skilful designer, and few modifications were needed for series produktion. The square-section fuselage has internal frames but only four longitudinal stringers running along its outer corners, supplemented by stiffening corrugations in the otherwise flat side panels and a spine that doubles as dorsal fillet. The fixed fin carries a conventional rudder, while the horizontal tail is an all-moving ´stabilator´ pivoted about its spar with a long dual-purpose anti-servo and trim tab. Each is swept forward three degrees, and just seven pressed-out rips form its thin modified NACA 23009 section on two spars, one an I-beam and the other U-channel, attached by precision bolts to the top of the fuselage and braced by single struts with pherical (Rose) bearings at each end. The front spars, struts, main undercarriage legs, fuel tank, canopy hinge and seats are all carried by a single strong fuselage frame - number three. The occupants are accommodated between this and the stainless steel front bulkhead - another primary member, which carries the nose-wheel leg and engine. Every component was treated with cromate primer at manufacture and, looking inside an inspection hatch, one cannot see a trace of corrosion on the yellow-green surfaces. Mounted in four rubber bushings on unequal-length bearers, the good old reliable O-200 has a twelve-volt generator and starter but, in this installation, no vacuum pump, so the gyro instruments are driven by suction from twin sidewall-monted venturis. The main undercarriage leg fairings conceal simple undamped tapered spring-steel rods, and the nose leg has four internal coil springs, a friction damper and an extra external oleo strut. What look like a pair of half-springs behind it are the steering torque links. Under the sternpost is a little tail bumper. Originally all three wheels were the same 500-by-five size, but for soft field work G-AVLO now has bigger six-inch mainwheels with standard hydraulic disc brakes.
The lockable canopy lifts up and back, pivoting on the crash-arch above the spar carry-through (again on frame three), allowing each occupant to enter from his own sice using the step below the front cockpit corner and the handle in the middle of the coaming. Swivelling to swing one´s leg over the edge onto the seat, the other follows easily and you settle down into a surprisingly high-sided cockpit. Each occupant has a four-point harness. The canopy´s foam sealing strips are completely draught-free, and the heater is surprisingly effective. Alternatively, the elegantly simple over-centre lock in the middle of the canopy´s front edge can be set to hold it a couple of inches open for cooling on a sunny day. For safety this is backed-up by a pair of side latches.
Primary controls are a touch novel. The throttle plungers droop down as they protrude from the outer ends of the panel with a friction adjustment below the leftone, while the central miniature control column is split to form a y-shape with the PTT button at its fork. Although unconventional, this ergonomic control ´catapult´ is very confortable to use because the angle of its nearest arm is ideal for a relaxed wrist, and the transmit switch can easily be hit the heel of one´s hand. The arragement also means the left-seat occupant can fly with his right hand while controlling the engine with his left - much nicer if, like most of us, you are right-handed.
Two inches broader than that of a Cessna 152, the forty-inch-wide cockpit feels much roomier because of the far superior visibility. Ahead of the pilot a neat black fibreglass binacle houses the six main instruments: ASI, horizont VSI, altimeter, turn-and slip and DI with the compass on its top. On the right panel are starter t-handle, engine instruments and Narco 12D nac/com radio with its OBS. In between are the flap switch, its vertical pin-in-slot indicator, and the mixture and carb heat knobs. Below these, in a slim central pillar, are ammeter, rotary mag key-switch, fuel pump switch and circuit breaker with fresh air vent and cabin heat plungers alongside. The elevator trim knob slides along a slot in a lower centre console with the brake lever along its left side.
The dished seat pans will take parachutes, but ´LO has cushions that can be replaced by soft luggage on a long trip, while behind the seat backs an eighteen by eighteen by thirteen-inch baggage compartment will hold two small suitcases weighing up to 45 pounds. Behind your head, between canopy and fuel tank, is a useful shelf for maps and flight-guides and even a dinghy on over-water trips. There is also stowage space under the seats and beside the occupant´s legs. John and his wife have carried all they needed for a fortnight tour of Europe in the aeroplane without discomfort.
The 22 gallon fuel tank above the luggage locker ensures a positive head of pressure and uninterrupted feed in the event of pump failure, while its filler neck protrudes through the canopy top.The engine and airframe combination are approved for ordinary motor fuel, the on/off tab is on the left sidewall and, having calibrated it himself, John says the gauge under the left throttle is the most accurate he has known. This incorporates a red low-level light which starts to flash with ten litres remaining and comes on steady at five litres (one gallon - enough for a ten minute precautionary cicuit and landing).
Following a couple of primes the little Continental fired up at the first attempt - as they always will - and after releasing the external nylon ratchet on the handbrake I soon discovered that taxying the Bölkow was dead easy. The visibility is superb, and the light and direct steering very effective, its twenty-degree authority allowing a tight turning circle although, with the wings apparently sprouting from one´s shoulders, the lack of parallax makes it a bit difficult to judge tip clearence absolutely accurately without leaning well forward.
The Bölkow´s maximum aerobatic (utility) weight is 1325 pounds, restricting the fuel load to thirteen gallons - enough for a whole two and a half hours of excitement - but with a full tank and two 170-pounders aboard for our first flight the aeroplane was exactly on ist 1390-pound Normal Category limit, so, operating from Popham´s grass we used ten degrees of flap to reduce the lift-off speed.
Taking off is very easy. The aeroplane accelerated surprisingly well and lifted at fifty knots in just 200 yards. Climbing at 65 and 2550 rpm returned an initial rate of 600 fpm against the stopwatch, and revealed an unsurpassed view of the world around. Many European lightplanes have better visibility (and often, incidentally, superior handling) than their U.S. conterparts, but I have flown only three with a truly panoramic view of the world outside - the old SNCAN (Nord) 800 series, the ARV Super Two and now the Bölkow Junior - and they all share the same forward-swept, shoulder-wing configuration. Putting the mainplane level with or just below the pilot´s eyes, but behind them, where it is only a thin obscuration to the horizontal view rearwards (easily overcome by lifting or lowering one´s head), means it does not block sight of ground or sky at all.
Some people choose to fly high-winged aeroplanes while others prefer low-wingers, an individual´s selection often stemming from the type on which he trained. I have flown dozends of each and frankly I do not care wether my mount-of-the-moment has high- or low-set wings so long as I can see outside properly. Sadly, very few light aircraft really possess adequate vision, but the Bölkow in one that definitely does.
The areoplane´s controls are also delightful. Having been warned that the small cable-operated ailerons were heavy, I fond them not only precise and quite light but surprisingly effective for their size - probably a consequence of the small 26-foot span - conferring a respectable roll-rate and, with their wellarranged differential action, needing just the slightest touch of the cable-operated rudder for accurate coordination at big deflections - a good trait in a trainer. The pushrod-actuated all-moving slab tailplane is equally effective and responsive. So our slightly ugly duckling turned out to be a very agile little swan with really nice handling. Longitudinal stability is good, directional stability very strong, and laterally it is just right, the wings staying at exactly the applied bank angle until you vary it.
Maximum cruise power of 2450 rpm gives a brisk 98 knots with a consumption of 4.75 gph at a quite acceptable headset-off sound level - surprising considering the proximity of the engine, and a tribute to the effiency of its twin silencers. A lower 2350 rpm still returns a very creditable 90 knots for a frugal 4.25 gph, conferring a five-hour endurance and 450 nm still-air range. John works on four hours practical safe flying time and 350 nm - quite sufficient for touring as well as the sightseeing that its superb visibility encourages.
Because of our weight on the first flight we were limited to erect manoevres so, HASELL checks complete, and a twizzling steep turn combining with the goldfish-bowl panorama to display the certainty of no nearby traffic, we throttled back to sample its stalling behaviour. As speed reduced a marked airframe buffet started at 55 knots, followed by the rather superfluous horn at 50 and a gentle ten-degree pitch down at 41 IAS , the left wing displaying a tendency to fall away slightly first, leading to a 150-foot height loss. With the engine running at 1500 rpm these speeds were slightly less, and again the left wing dropped a little with the nose.
Ten degrees of flap made a material difference to the speeds, buffet starting at 48 knots and leading to a steep 800 feet per minute mush in the level attitude at a stable 35 knots rather than a proper break, although slowing more rapidly caused a ten-degree straight-ahead pitch-down. Full 35-degree flap reduced the onset of buffet to 50 knots and horn at 45, but I could not induce a g-break without extreme mishandling; the aeroplane simply plummeted, buffeting and nodding, at 900 fpm in a ten-degree nose-down attitude.
On a subsequent summer evening with just ten gallons of fuel we were able to sample some Bölkow aeros. The maschine´s V ne is 135 knots, V no 125 and max manoevring speed 106, while it is certified to + 4,4 and - 1,76 g. We started by climbing to 6000 feet (which took some time on this warm day, but enabled us to enjoy a little sightseeing while I re-acquainted myself with the aircraft´s handling). Intending to begin with some spins, I discovered to my disappointment that, despite full pro-spin controls, it was impossible to induce autorotation for more than half a turn before it became a spiral dive with increasing airspeed. After three attempts, using all the tricks both John and I knew, we gave up and went on to aeros proper.
Like so many `aerobatic´ types of its generation the Bölkow Junior has neither inverted fuel nor lubrication systems, so the engine will only windmill when inverted. Oil will also dribble from the filler neck when upside down, but this does not preclude negative-g manoevres - although the owner`s handbook suggests limiting the number of slow rolls to twenty or thirty per flight - which is fine by me!
Most figures are entered at 120 or 130 knots, requiring an airspeed-increasing full-power dive, but because of the fairly fine prop the throttle setting has to be slowly reduced to stay within the 2750 rpm red-line, so each manoeuvre tends to start 500 feet lower than expected. Given the aeroplane´s limited power and inertia, I was surprised how slow and big a loop could be, and found them easy and pleasant to perform, although the stallwarner tended to bleep over the top, and you can tell by the buffeting when the wing is working hard under highish g. Because of the small ailerons, rolls are perforce slow rolls, but they are not hard to accomplish - although of course the engine stops producing power once the negative g comes on.
An aileron roll is even easier, with the advantage of continued power throughout, and means simply diving to 110 knots, lifting the nose twenty degrees above the horizon, whanging on full aileron and waiting for the world to stop its slow revolution - which happens at twenty degrees nose-down and rather lower altitude, but with enough speed to do another right away. Chandelles are easy and truly delightful. Pulling up for a stall turn at 120 knots gives a very short vertical segment because of the low momentum and power, but there is plenty of rudder authority at 55 for the bridge in either direction and to stop the swing accurately going downhill. A gentler pull after diving to 130 gave a slightly longer upward line for a cleaner figure.
Obviously, with only a hundred tiny horsepower, the Bölkow hasn´t enough grunt for a proper sequence unless you have lots of height or sufficient time and patience to climb again after each few manoeuvres. It will never be a competition mount, but with such exellent visibility and nice controls it is a truly delightful Sunday evening `flip-flop´maschine, and makes all simple manoeuvers easy to perform while demanding some practice and finesse with the controls for real accuracy.It would seem a very good, capable trainer for basic aerobatics.
When returning to the circuit, a minor niggle in the otherwise well laid-out cockpit is that, with stick and ancillary controls on the centerline where both occupants can reach them, one has to either cross over with the outside hand to operate flaps, trim, brakes and carb heat or else change hands on the catapult.
The plain flaps are quite long, extending all the way from wing roots to its short ailerons, taking up a good two-thirds of the trailing edge. Below their 79-knot limiting speed the spring-loaded switch will command a former Bosch windsreen wiper motor to lower them to any position through a clutch. The first ten degrees of extension cause a slight pitch-up, soon counteracted by the subsequent speed reduction, and further extension induces no further noticeable trim change although there is a difference in the aircraft´s `feel´ with flap out as well as an obviously considerable drag increase. The slightly sensitive pitch trim lever was almost superfluous throughout the flight.
With more than ten degrees of flap the outlook ahead becomes superb over the lowered nose. At the suggested approach speed of sixty knots with full flap it is exellent, and the aeroplane is very speed-stable. The delightful controls, already light, are really light at low speed, yet still have plenty of bite for close-in manoeuvering and good flare control. My first attempt was slightly fast at 65 knots, causing a noticeably long float, but on subsequent approaches, managing the speed better and reducing to 55 over the last arrow on Popham´s curving approach, we floated barely fifty yards over the downward-sloping ground to touch down lightly on the main wheels in a slightly nose-up attitude. There was still plenty of pitch authority to hold the nose-wheel off the ground and prevent bucking almost down to a walking-pace, while directional control was easy.
The aeroplanes maximum demonstrated crosswind is 20 knots, and with this rudder power I would not imagine that would induce much of a sweat. The only slight awkwardness is the distraction of having to reach over the brake lever ahead the control column with the left hand, but this would not normally be necessary, because without hammering the binders we stopped easily in under 200 yards.
What a shame, that only a couple of hundred Bölkow Juniors were ever made; but perhaps more are on the way. A 1970s attempt by Andreasson´s Swedish company MFI to market a tougher military version called the MiliTrainer for training and counter-insurgency (groundstrafing guerillas) sold only a few examples, and there is no longer any official factory support for the type. However, a few years ago there was a plan to build kits in Singapore, and more recently there has been talk of a new `MFI´ re-commencing production, so we may yet see more in the skies. As far as John is concerned, since it was originally designed as a homebuilt, its construction is so simple and rugged that he has found little need for any special parts.
An unexpected advantage of this lack of formal support is that it enables the machine to be operated on a PFA permit to fly, allowing greatly reduced costs, as the owners may do their maintenance, to the usual high standard but away from an expensively approved commercial establishment (although of course under the watchful eye of their inspector). Also its engine although originally lifed at 2000 hours, can be run òn condition´. Because it is all-metall the aeroplane can safely be kept tied down in the open, as `LO´ is, further reducing expenses. John reckons that with its good range, aerobatic capabilities, delightful handling agility, matchless vista and being so easy to fly, it is the ideal private or group aeroplane. After my brief acquaintance I am inclined to agree with him.