Posted Saturday, September 5, 2009 @ 11:36 AM  

The Fournier has a light but strong wooden airframe. There is not a spare ounce of mass, no fitting is bigger than it needs to be, and each component integrates with the others in innovative and highly efficient ways. Built of pine and spruce, with Finnish birch plywood and Dacron fabric covering, the structure weighs a mere 628 pounds. The long, 11.2 to one aspect-ratio wings’ laminated pine spar and ply leading-edge D-box form the trusty and oft-used NACA 23015/23012 aerofoil. This wing section was originally perfected for sailplanes, and its convex under-surface is good for inverted flight, but beware, it has a sharp stall.

There are four wheels, of which you can only rely on two. The bicycle main undercarriage has a single, small, retractable 500 by 5 main wheel with rubber bungee suspension and a steerable solid tailwheel with compressed rubber suspension. These are supplemented by two skinny under-wing outriggers (roller-blade wheels on nylon rods) to keep the wing-tips off the ground. The aeroplane will rock from one of these on to the other as you turn on the ground.

The engine is a French Rectimo-modified 1192cc 1960s Volkswagen Beetle car motor with single ignition and no carburettor heat, since the air intake continuously breathes warm air (although carburettor icing does occasionally occur). Rectimo claimed it produced 39 horsepower in ISA at sea level (or, at least, it might have, 1,000 hours and 36 years ago). Mine mustered 35.1 hp on a dynamometer.

You start the engine by standing ahead of the left wing and flicking the propeller downwards from behind. It usually fires on the second turn after six priming rotations with the throttle closed and full choke, plus six more turns the other way with full throttle and the coke off. Don’t ask me why, but this seems to be the only sure way of starting it from cold, whatever the weather. Be sure you close the throttle before switching on the ignition.

Then you climb over the leading-edge into the two-foot-wide, grey-painted cockpit. This is snug, but not tight, with a comfortable, g-resistant, semi-reclined seating position and a proper five-point aerobatic harness. The side-hinging canopy latches and locks on the left, but can be jettisoned with a lever on the right. Its postcard-sized clear view panel on the left incorporates a scoop for pilot cooling, which is further enhanced by air vents fed by leading-edge inlets, which discharge into your face from ducting below the panel. You can vary the flow via valves behind your calves. A small baggage compartment behind the seat holds the radio’s battery, and will also take a soft overnight bag or a one-man tent and sleeping bag.

By your right thigh is the undercarriage lever. To raise the main wheel, you pull a trigger on the forward face of its small locking handle to the right of the wheel cover, and slide that backwards. The wheel unlocks and swings half way, bringing the long lever upright, so you just pull it down to lie flat beside you. Listen and feel for the locking click. Extension is the opposite – pull the trigger, slide back the latch, push the main lever forward until it clearly locks home. Then check the locking latch is clicked into position properly. The limit speed for operation is sixty knots, although flight is OK up to Vne with the wheel down. Two spring-loaded wheel-well doors are pushed out of the way by the extending wheel, snapping shut when it retracts. Under the belly, either side of it, two hardwood runners more or less support the airframe when I forget to lower the wheel.

There are no flaps, but another lever on your left extends a row of curved spoilers above each wing. A third lever, forward and to the right of the central black plastic main wheel cover operates the recoil starter. Connected by cable to a small cog that engages with a big one on the propeller’s back-plate, this eases the prop over just one revolution, so it does not work on the ground, but it is perfect for airborne re-starting.

A small instrument panel holds the usual flight dials in the centre, with engine gauges around its edges. To the left are the red stall light and a yellow one with a buzzer for undercarriage warning, which sounds with either the throttle closed or the airbrakes extended. There is no green ‘Down and Locked’ light as there was on British examples. Below these are the plunger throttle and lockable brake lever. Over on the right are choke and fuel cock knobs (forward for take-off as usual). The float-and-bent-wire fuel gauge is in the fuel cap, out on the forward decking, where it is always in your line of sight. An alternative aerobatic fuel cap incorporating a ball valve prevents fuel trickling out during prolonged inverted flight.

Posted Saturday, September 5, 2009 @ 11:42 AM  

Loops, aileron rolls, slow rolls, barrel rolls, quarter-clovers, Cuban eights and reverse Cubans are easy if you start above 100 knots or 110 mph, but stall turns are rather more difficult.

The Fournier spins nicely, and quite quickly and well nose-down, to both the left and right, recovering predictably in three-quarters of a turn. I have only flown eight-turn spins, but South African airshow pilot Peter Goldin told me: “The most turns I have done is fourteen”.

A quarter vertical upward roll is possible and, with a ‘humpty-bump’ pull over and another quarter roll on the down line, makes a useful turn-around manoeuvre. Another useful Fournier turn-around is the half-flick to the inverted and pull-through. Inverted flight is easy (although of course the engine stops).

For gliding, you kill the engine by turning off the fuel, and then opening the throttle and reducing speed to just above the stall to stop the propeller. Do not try stopping the engine by switching off the ignition, for it could become flooded and may not start again. Positioning the propeller horizontal with the hand-start lever minimises the drag, giving a useful quoted 1:20 glide ratio at 54 knots (62 mph), or a sink rate of 1.30 metres per second (256 feet per minute) at 49 knots (57 mph). These manual figures are ‘with 9 litres fuel and minimal equipment/baggage’. Truthfully, at normal weights, the glide angle is nearer 1:16, but that is still good for a powered aeroplane.

An infinite variety of glide angles can be achieved merely by leaving the engine ticking over, and cracking open the throttle a bit when you can’t find lift. Although its power-on ceiling is 19,685 feet (itself tremendously impressive on a mere 39hp) an RF4 once held a world-class record by climbing engine-off to 36,800 feet in mountain wave.

Normal descents are made at sixty knots with the gear up and throttled back to just before the warning horn sounds, although the steepest descent is achieved at 95 knots with throttle closed, wheel down and spoilers extended (sideslipping if necessary, to nearly double the descent rate). There is little yaw or pitch trim change with power or spoilers, but the elevator trimmer, operated by a small lever on the right coaming, is effective, if a trifle sensitive. Be gentle, it is easily broken, and irreplaceable.

Posted Monday, September 7, 2009 @ 04:08 PM  

Since I will hopefully be starting my RF3 adventure in the not to distant future, all of this is really good info.

Gruß

Posted Thursday, September 17, 2009 @ 10:51 AM  

The technique of taking off in crosswinds involves starting on the downwind side of the runway, although the problem is not quite so difficult as a crosswind landing, because the slipstream helps rudder effectiveness. The normal swing on take off is to the right, so a take off with a strong crosswind from the right is the most difficult case. Taxying a Fournier in a cross/tail wind has to be attempted to be believed, but is also possible with practice, although it can involve progressing in a series of 270-degree turns.

Away from the circuit, the stall is viceless, with or without power or spoilers. Clean, the aeroplane tends to take a little time to reach the stall, because of the marked absence of drag, but when it comes, it is gentle and unmistakeable, preceded by the warning light at around 6mph above stall speed, and with a little light high-pitched buffet, and followed with little loss of height, with or without power. It is not necessary to use any forward pressure on the stick, and in fact is undesirable, as this only leads to increased loss of height. Power on, the stall occurs at quite a high angle of attack and may be accompanied by a wing drop, but control in all axes remains good right up to the stall. The RF-4 is a little more sharp in its reactions, but not at all nasty. The height loss in all cases is unlikely to exceed 300 feet.

Steep turns are most enjoyable, and can be executed at very high bank angles with no trouble, although it can be interesting to watch the skin on the upper wing surface wrinkling with the high ‘g’ loads. Very little up elevator is needed at bank angles up to 45 deg, while speed drops off very slowly at bank angles up to 60 degrees, and only a little extra power is needed. However, it is very necessary to use rudder to execute all turns, as, despite the current use of differential Frise ailerons the adverse yaw is very marked.

There is very little yaw, and little change of pitch trim with change of power, and the elevator trim, operated by a small lever on the right of the cockpit, Jodel style, is more than adequate, although a little coarse. Normal descents are made with the gear up and throttled back to just before the gear warning horn sounds, at 68 mph. The steepest descent is achieved at 62 to 93 mph with the throttle closed, gear down and spoilers extended.

The optimal approach speed in smooth air is 62mph with spoilers retracted, or 68mph with spoilers out. In rough air add 6mph. One point worth noting is the lack of pitch change with application of spoiler, which, however, does produce a marked change in rate of descent. As a consequence the flare has to be commenced a little earlier than might be expected, although the light elevator can lend to over controlling here again. The normal approach is executed power off, with gradually increasing spoiler, with a target of full spoiler and 70mph with the field “made” at 200ft. This is not difficult, although the approach angle is quite steep. The advantage of this system is that if you appear to be landing a little short, you can take off a little spoiler, and extend your landing point without changing speed, power, or trim. With practice very accurate touchdowns can be achieved, and one can imagine a safe forced landing in this aeroplane to be within the capabilities of any pilot with a few hours Fournier time.

Posted Thursday, September 17, 2009 @ 11:00 AM  

I thought the smart thing was to cut n paste it in here, so here it is...

The more you read, the better you are prepared, and the more other folks' viewpoints, the better too.

Obviously, like the foregoing, I take no responsibility for any of this, it's just for your info.

And hey, don't you just love some of the archaic language?

Yours, Bob