Airtest – Rushmeyer R 90-230 RG

The family’s airframes are predominantly made of glass fibre with Rohacell foam cores, although a long weight saving stainless steel tube runs back through the roof from the upper firewall to the rear fuselage, dividing the windscreen, supporting the doors and providing rollover protection. While there is also some carbon fibre strengthening around the door frames, glass fibre predominates because of its superior lightning resistance over carbon fibre’s. Naturally, all airframes incorporate earth bonding to the most restrictive of either the latest German or the Faa requirements.

Construction uses the newly certified Basf vinyl ester resin Palatal A430 which is much less toxic than established epoxies, less mixture critical, less water absorbent and more resistant to high temperatures. To verify its strength and qualities the firm made and tested over 15,000 samples. The Ruschmeyer’s fuselage and wing have been proved to 56,000 hours, allowing an 18,000 hour certificated life (a good deal longer than most light aircraft ever survive) and its test components passed all strength tests including those with intentional damage and deliberately degraded adhesive bonding.

Unlike almost all other current designs (which depend on the ‘grandfather rights’ of their pre-existing family line to sidestep modern strength, fatigue and damage tolerance requirements) Ruschmeyers fully comply with the current Far (Jar) 23 to amendment 34. They also incorporate the increased 1.75 safety factor required of composites (metal and wood airframes have a 1.5 margin). Although this might be expected to result in a little added weight, the Ruschmeyer’s airframe is actually lighter than its higher powered rivals, the Bonanza F33, Commander 114B and Mooney Tls. It should also have a longer life, extra strength margins, much higher safety levels and impunity to corrosion.

Preproduction aircraft No 3 D-Eerm’s exterior finish is as smooth as we have come to expect from composites. Displaying an obvious quest for low drag, its door and control surface gaps would fare well in Mercedes’ ball bearing test. The tapering wings have a 6.97 aspect ratio, a modern rain tolerant laminar flow Wortmann aerofoil, leading edge stall strips and fashionably uptilted tips (not for reduced drag, but to improve lateral stability). The small ailerons have slight differential action, with deflection limited by concealed mass balances. Inboard are big three position electric Fowler flaps with similarly shrouded hinges and mechanism. Fuel is carried in ‘wet wing’ tanks holding 236 litres, sufficient for more than eight hours of supereconomy flight. Their filler cap wells have flush-fitting thief-proof covers which can only be unlatched from within the cockpit while both wells and latch cables have under-wing drain holes.

The tail surfaces are similarly configured to those on the Wassmer family because these had good stall and spin recovery characteristics, although they incorporate a fixed tailplane. Since this is composite, the Vor aerial can be hidden inside. All controls are operated by duplicated push-pull rods, and the elevators have a flap position input to compensate for trim changes. The left one also has a combined trim and anti-servo tab to increase stick force to acceptable levels.

The six cylinder Textron Lycoming Io-540 usually develops 260 horsepower (195kW) at 2575rpm, but in this installation is limited to 230hp (173kW) and 2400rpm to reduce noise. Presumably this will also help prolong engine life beyond the normally stated 2000 hours. Thrust is generated by a reduced diameter four bladed wood and fibreglass Miithlbauer prop on a 7.6cm (8in) spacer. Combined with an efficient silencer, this carefully researched installation beats the stringent German anti-noise 74.0 dB(A) full power overflight limits — themselves 4 dB(A) more restrictive than the Icao limits – by an impressive 8.1 dB(A). The cowlings are sleek and compact, with a pair of adjustable under-belly cowl flaps and a small left-side oil cap and gascolator drain inspection plate.

Entry is via non-slip stripes along each wing root and over conveniently low sills through a pair of distinctive, solid-feeling gull wing doors. (Both a step and a handhold will be available as options, since the wing is really rather high off the ground to do without). The doors can both be opened together, their motion is damped by spring struts, and they close gently without slamming. Two horizontal locking pins extend with an easy 90 degree twist of the handles. The interior is finished to a very high standard and among the many nice touches are overhead grab handles to assist entry and four headset hooks. Sidewall cascade heater outlets are supplemented by knee-side air louvres and four ball vents beside the reading lights in the roof.

The pilots’ seats are well shaped and comfortably reclined with a two position back angle and high quality three-point Pacific Scientific harnesses with adjustable shoulder straps (it has proved difficult to locate inertia reel units capable of withstanding the new 12g deceleration requirements). Sliding longitudinally, both seats rise as they move forwards, but the rudder pedals are fixed. The separate seats in the 1.14m (3ft 9in) wide rear have plenty of space, and I found the leg room acceptable even with the front pair fully aft. All seats had adjustable headrests, were well padded and covered in expensive leather. The front ones have seat back pockets, and during certification testing all were crash proven to 12g vertical and 10g longitudinal.

Not only is there a small stowage compartment between the rear pair, but the 8 cubic metre baggage area accepts up to fifty kilos and is accessible over their backs in flight. This can also be reached through a left-side door which, like the fuel tank caps, can only be unlatched from within, using a button in the left main door surround. The cabin’s aft wall shows further evidence of the company’s innovative detail touches with integrally moulded recesses for first aid kit, fuel tester, fire extinguisher and tool kit.

The left instrument panel has a full set of Ifr dials and the appropriately shaped undercarriage switch for its electro hydraulic landing gear. Engine gauges (including a very useful Ckas fuel computer) are scattered around a Stormscope (still under evaluation) on the right, with flap switch and novel Lcd indicators for flap and trim position. This development airframe has a conventional central radio stack with an add-on Gps on its coaming, but production machines will have miniaturised radios with a King Ks70 Gps as standard. Despite the Ruschmeyer’s internal quietness, all aircraft will have intercom, but an optional sophisticated, switchable, four place stereo system would allow internal conversation and Cd entertainment without disturbing the pilot’s radio communication. Both panels drop down for maintenance after removal of a few screws.

Five coloured lights above the radio stack warn of low generator voltage, low oil pressure, stall warning and aux pump and pitot heat failure. Below the radios are the six electrical system switches. Running aft from this, the moulded centre console contains the robust, low friction engine controls, four position fuel selector (left, right, and two offs) and manual elevator trim wheel. The emergency undercarriage lowering switch and a usefully sensitive throttle friction lever are on the console’s left face, while there is an approach plate stowage below the cowl flap knob to its right.

Curving sinuously up from under the front seats and allowing an unobstructed view of the whole panel are the two vinyl sheathed control columns. Held central and forward by quite strong control system springs, each stick is surmounted by a military looking stick top box with four buttons around the central electric pitch trim rocker switch. These operate Ptt, transponder ident, undercarriage horn cancellation, autopilot control wheel steering (Cws) mode and autopilot disconnect.

Heiner raised my eyebrows by inducing an immediate start-up from the fuel injected Lycoming, a trick he repeated successfully several times that day regardless of engine temperature, suggesting unusually effective fuel system shielding. Due to the multi-bladed prop, the engine idles very smoothly.

For my first flight we carried 77 litres of fuel to weigh 1128 of a permissible 1350kg with a forward C of G. This well-equipped early airframe weighs 920kg, so four adults and their personal effects would have allowed 180 litres of fuel for a 2.5 hour, 400 mile flight. Topping up with the full 250 litres would have limited useful load to 250kg (three adults with 25kg of baggage or Mum, Dad and two 50 kilo ankle biters).

I would normally have expected any evaluation of an aeroplane in this class to be conducted entirely from a long, hard runway but, surprisingly, we were able to do the whole thing from a grass Ala. Although the trailing link undercarriage gave a rather firm ride over these undulating surfaces, and the direct nosewheel steering was a little heavy, the aircraft displayed a good 6m (20ft) turn radius and the brakes worked well. The main gear doors are connected to the undercarriage legs for simplicity and there are no inner wheel covering doors. When I set flap at fifteen with the three position switch the stick was noticeably displaced slightly rearwards by its trim compensation mechanism.

Full throttle gave good acceleration with very little noise and sixty-five knots (120kmh) came up after only ten seconds, when rotation required a firm, positive pull on the stick for a clean lift-off. Plenty of right rudder was needed to keep straight, both on the runway and once we were airborne (unfortunately this aircraft had no rudder trim), but the need for this lessened as speed rose.

Flap and gear retraction each took a little over five seconds (with no trim change) and I timed our climb to 2500 feet as 1200 feet per minute at the best rate speed of 95 (still needing some right rudder). This accords well with the sea level, max weight published rate of 1130fpm. Thanks to that elevator down spring, pitch stability is positive in the critical full power climb case, while all-round visibility is excellent, better than in most production singles. By leaning forward you can see downwards ahead of the wing, straight up through the large high-topped side windows, or over your shoulder to most of the tailplane. The nose does not obstruct the view ahead, even in the climb, and it is quite out of the way in the nose-down cruise.

High speed long range cruising is this type’s métier, and full throttle (65cm) with max rpm (2400) at 3000 feet gave us 160 knots (296kmh) Ias which trued out at 170 (315) (Vne is 196 [363] Ias). Since ‘full power’ on this derated installation produces only 230 horsepower (172kW), this could be regarded as 85% power. A more normal 75% figure of 58cm (23in) and 2350rpm gives a quiet and comfortable 155 knots (287) Ias (165 [306] Tas). The mixture lever has a very sensible gate at approximately the best Egt position to prevent inadvertent over leaning; pulling it back to this reduces fuel flow to fifty litres per hour, giving a four hour safe endurance or 600nm (1110km) range.

Maximum range and endurance are stated as 870nm (1610km) and 7.8 hours, using 38% power. Heiner’s economy cruise of 54cm (21in) and 1800rpm gave us 125 knots (232kmh) Tas with a fuel flow of 31 lit/hr and a predicted 5.5 hours endurance on the fuel computer, but this setting induced the first slight signs of engine vibration. Although undoubtedly fuel efficient, I have reservations about the effect of these ‘over-square’ configurations on engine life. Otherwise the six cylinder engine generated almost no vibration and very little sound. What slight wind noise there had been at higher speed now diminished to little more than a sigh, making conversation quite possible without headsets, which will be good news to those who hate these hairstyle crushing encumbrances. There is no doubt that long distance flights in this comfortable aircraft should be no hardship.

This aircraft is positively stable in all axes; nobody ought ever to lose control of this aeroplane. Although its stick forces do feel slightly heavy when going quickly, this has the advantage of making it appropriately difficult to deflect from the straight and narrow. While forces reduce considerably as the speed drops, they could never truly be said to be light, and this does ensure that a sneeze won’t break the airframe (as it might in some of the current kitplanes) while giving the machine a Teutonically solid and safe feel. Nevertheless the roll rate is a more than adequate 45 degrees per second, with very little adverse yaw. Of course the autopilot would normally be used for long flights, and this worked well during my brief periods of its use.

As the speed dropped below 100 knots (185kmh) there was minimal trim change as the controls became lighter so the low geared electric pitch trim was little needed. On completely closing the throttle the bleeping undercarriage warning horn sounded; this can be cancelled when clean, but not once full flap has been lowered. The clean stall occurred at 59 knots (109kmh), preceded by a high-pitched continuous horn and red light at 66 knots (122) and buffet at 64 (119). The gentle pitch down came with a very slight and easily corrected right wing drop and a height loss of less than 150 feet. Pulling too hard and too quickly caused that insistent horn to pipe up again, warning of an imminent secondary stall.

Flap can be lowered below 105 knots (195kmh), and fifteen degrees reduced the straight ahead stall speed to 57 (106). Full extension with gear down further reduced the no-fuss stall to 54 knots (100), again without a wing drop. Handling a couple of knots above the stall was predictable and not too sloppy, while stalling clean with approach power led to a nose high straight ahead break to the level attitude, still at 58 knots (107kmh).

Although its whole airframe is designed to 9g, the Ruschmeyer is not yet certificated for spinning or aerobatics and G is currently limited to +3.8 and -1.52. However test evaluation of these manoeuvres is authorised, so Heiner was able to demonstrate a barrel roll after a brief initial full power dive, bringing up the nose for 140 knots (249) before applying full aileron. A slightly higher exit speed allowed a nice big loop with a tweet of stall horn over the top, followed by a pull straight up into a stall turn, then a half Cuban. Spins of up to four turns have repeatedly been demonstrated without recovery problems and Utility Category approval is expected soon.

Though I was flying this aircraft in familiar territory I found that the speed at which it travelled resulted in my looking down at terrain landmarks speeding by far more quickly than I am used to and the usual forward thinking is needed at these swift speeds but, with some planning, field approach deceleration need be no problem.

As we descended the wheels took eight seconds to lower using the normal system (Vle is 140 knots [259]) but extended almost instantly with the emergency spring assisted gravity system after first reducing speed and power. A convenient circuit speed is ninety knots (167), with an equally easily remembered twenty inches (51cm) and 2000rpm (twenty/twenty) reducing to fifteen inches at 75 knots (139) and 500fpm on a fairly shallow final approach. Although aerodynamically clean, the aeroplane is easy to handle and positively speed stable, with excellent visibility for both right and left hand circuits and on final, due to its nose down attitude, low coaming and sloping cowling.

Even with the nose well raised, the sloping cowlings do not obscure the view ahead. Heiner tells me that maximum flap setting might be increased to forty degrees on the fixed gear models (which could accept the drag increase of the necessary external hinges). All our landings, both two up and three up, used less than half the Ala’s 900 metre length, and there was plenty of space for a brisk touch and go. The only requirements were to retract the flap to fifteen (easily done with the gated switch), to counteract the slight pitch up, and to use enough right rudder to control all that torque.

An important factor here was the precise and immediate positioning available with the aeroplane’s stick control (especially for a curving approach). Nor was there any of that sloppiness you get during the flare when a yoke’s torque tube protrudes at near full extension from the panel. As well as helping fulfil the brochure’s promised ‘joy of flying’, this control column makes short field and strong crosswind operations quite straightforward, something you could not say of several of the type’s competitors.

The Ruschmeyer’s interior may not be as spacious as those of its older technology rivals such as the Commander 114B or the Bonanza F33, but it is at least as well-appointed, with a bigger cabin than the Mooney Tls’s. On 30 (22), 56 (41) and 40 (30) less horsepower (kW) respectively its cruise speed, climb rate and range are near identical to its competitors at a much reduced fuel consumption and far lower noise level (both inside and out). It flies at least as well as any of the others and, despite a fairly high wing loading, it has good short field performance because of its advanced aerodynamics and low weight.

By 1996 the company plans to expand the family with 180hp (135kW) and 230hp (172kW) fixed gear versions, a turbocharged 250hp (187kW) retractable, an aerobatic trainer (with jettisonable doors, parachute seats and inverted systems) and a 420hp (315kW) Allison turboprop derivative. This first top of the line model is aimed at the discerning elite, but with a price tag around $A300,000 it is still very competitive with its rivals. If the company can tailor its other versions’ prices to their respective markets, they should find they have a very popular range of products. What more can I say of this smooth, manoeuvrable, sophisticated and near silent aeroplane than to suggest it is “The flyer’s Ferrari”.