Three of a Kind

For the record, the Cougar’s single-engine climb is listed as 200fpm; Beech Duchess 23Sfpm, and Piper’s Seminole 217fpm in ISA conditions.

However, the GA-7 Cougar is a handsome beast, sitting high and selling well in Australia at the time of evaluation. The type was born soon after Grumman American set the light aircraft world on its ear with an astonishingly marketable range of light singles.

With the 180hp Tiger well in focus, Grumman American thought hard about a retractable single before venturing into the light twin range.

Limited resources precluded the Tiger’s folding-leg development, and it was deduced that retracting the Tiger’s undercarriage would not bring about a significant increase in performance.

Senior VP Roy Garrison batted hard for a light twin as opposed to a high-powered new single, using persuasive logic. He won part of the battle.

Grumman American abandoned the original idea of a fuselage about Tiger size bo as tin g a 160hp engine each side, and went in hard for a new design satisfying the FAA’s hardline regulations and giving the end-user the pleasure prestige and satisfaction of a retractable light twin.

What has emerged has been the first of a new breed, a transitional twin, multi-engine trainer, private type suitable for cross-hire to training establishments – call it what you will, depending on your fancy.

The Cougar in North America and Europe have been marketed with twin-engine safety over high terrain and savage Northern Hemisphere weather in mind. Icarus Aviation Services, headquartered in Bankstown and Gulfstream American distributors, have altered the focus to private ownership as the first goal, followed by training.

This orientation has apparently been successful. Icarus have already sold the first three Cougars allocated to Australia, have definite prospects on the fourth and say they could sell another three or four before the end of 1979 – if they could get their hands on them.

Department of Transport certification has been successfully accomplished, the only restriction being a 75lb weight penalty during single-engine ROC flight phases.

One thing the Cougar has achieved during its design and production workout is to notch a Vmc of 67 knots, 10 knots below clean stall speed and two below dirty stall numbers. This admirable feat has earned the Cougar special insurance premiums in the US.

The aircraft has also achieved economy, efficiency and performance wedded to totally acceptable bonding techniques.

Icarus says the Gulfstream GA-7 Cougar has no pretensions about being a world-beater. It is subject to the same arguments about payload versus range as any other light twins, but if it’s the type of aircraft the customer wants then it’s the best in its class.

The first Cougar in Australia, now VH-IPX with 787 hours’ on, was provided by Icarus as the test vehicle for evaluation along with capable ferry pilot Mary O’Brien.

India Papa X-Ray originally bore Serial 22 when it was born in Savannah. For the record, the second and third Cougar marketed by Icarus are Serials 39 and 70.

Study of the Operating Handbook produced a number of late amendments; as expected, most of them dealt with single-engine go-round performance, warning that level flight may not be possible in certain temperatures, and at certain altitudes and weights, on an asymmetric go-round.

A descending turn into the “dead engine” is usually the first sign of an engine-out situation. Be that as it may, the Gulfstream American Cougar’s performance shows none of the dreaded stall-spin symptoms feared by most multi-engine pilots.

A Cougar walk round does much to enhance an already favourable first appearance. The high ground sit gives the impression that the GA-7 Cougar boasts much more power than that housed in the two 160hp Lycoming four-cylinder 0- 320-D1D motors. (Recommended TBO is 2000hrs).

Two 73in Hartzells provide the urge, each available with unfeathering accumulators as an option. Incidentally, engines arc not inboard-rotating on both sides as in other light twins, in the interests of economy. Power loading is booked at 11. 88Ib/hp.

This arrangement proved to be a non-problem during twin- and single-engine flight.

A wingspan of 38ft Bin gives a total wing area of 184 sq ft, embodying a very respectable lift-speed wing section marriage.

Wing loading is listed at 20. 65Ib/sq ft.

During the walk round, a number of salient points emerge the forward retracting nosewheel which limits gear retraction speed to 115 IAS; the massive amount of bonding in construction (the lower cabin section is completely surrounded by aluminium honeycomb three windows a side giving ample visibility for pilot and passengers; an enormous rudder and significant other control surfaces operated by a cablc pushrod mix.

While inspecting wings, I remember there are two stall warning sensors actuated by pressure-raised stall detectors in the right wing leading edge. The inboard one operates between five and 10 knots above flaps-up stall speed, the outboard one sounding off when between five and 30 degrees flap is extended.

An overall look at the Cougar is pleasing, an impression of workmanlike no-fuss yet aesthetically acceptable lines being echoed during an air-to-air eyeball encounter.

Cockpit layout and accommodation, visibility and control accessibility are sensible and direct. Some pilots have queried the flap selector (low right of power quadrant), but most light aircraft makers have chosen this position.

The panel is generously deep but does not interrupt forward vision. Flight and IF instruments occupy the panel immediately in front of the pilot, switches and undercarriage selector below. To the right are navcoms with temperature and pressure gauges below.

Power and rpm displays sit under the left panel, array, about 11 o’clock from the power console. Circuit breakers line up at the bottom right-hand corner of the right panel section, and an annunciator panel tops the instrument coaming lining.

Entry and exit from the one door (right side) present no problem to anyone bar geriatrics. The seating is adjustable and comfortable.

Fuel management is a simple OFF-ON-CROSSFEED drill and is well-placed as are most items on board. Among legends are max manoeuvring (120kts IAS), max gear extension (145 IAS), max gear retraction (115 IAS), max, gear extended (145 IAS), and altitude loss during one engine-out stall (300ft).

Manual numbers worth remembering include two-engine best angle of climb speed (81 IAS), best r. o. c. speed (95 IAS), cruise climb (100 IAS), balked landing (80 IAS), flapless approach (80-85 IAS), 30 degrees flap approach (75-80 IAS) and max demonstrated crosswind (15 IAS).

Normally aspirated starts are made on the left mag, with the right magneto on after the start. Taxiing is light on the feet, and a 35-degree each-side nosewheel travel means a turning radius measured on the outboard wingtip of under 48ft.

Even during ground handling, the high “sit” in the cockpit gives the pilot a high degree of command, in reality, and a general feel.

Engine runup is a triple exercise; at 2200rpm the props looking for a normal drop of between 150-250rpm. At 1800rpm, check carburettor heat and mags, alternators and instrument air pressure gauge. At 1500rpm check prop feathering – prop levers in Feather, then low pitch, allowing no more than 500rpm drop before bringing throttles back to 800-1200rpm.

The Cougar grosses at 3800Ib – empty weight (basic) 2515 with 1285Ib useful load. With three-quarter tanks on both sides and three bodies on board (all fairly lightweight) the test aircraft still had about 300Ib to gross.

The outside air temperature was a simmering +30C on takeoff. The manual recommends power before brake release; there was no significant torque swing on a roll, Yr reached at 74kts IAS and wheels off in 1000ft – exactly on the book, but without flap.

Gulfstream American’s manual recommends the acquisition of a speed well above Vmca (61kts IAS) as quickly as possible, for obvious reasons. Throughout the speed buildup, there was little suggestion of any deviation caused by both props turning the same way.

Light back-pressure initiated a positive climb. Wheels up selected and transit light on, best r. o. c. speed of 95kts IAS was set up notching a steady 1000fpm with outside air temperature still nudging +28C.

Settings were eased back from 27 /2650 to the classic 25/25 and 100 knots indicated – right on the book figure for en route climb. It was immediately apparent that the Cougar is a quiet aircraft, a steady performer and already marked down as a stable platform despite an intermittent convection chop at 2000ft.

Two thousand feet higher, various settings were tried. The test Cougar bettered book figures in all cases – for the record, cruise performances listed include 25/24 (about 74 per cent) giving a carded 155kts TAS; total fuel consumption at those settings is about 21 US gallons per hour.

Setting up the best economy at 4000ft meant 57 per cent settings (20/2400) which cut consumption back to a creditable 12 US galls/hr and returned a TAS of 131.

The Cougar really shines at about 8500ft. Setting up 75 per cent power – 21/2700, and in -21C conditions, something rare in Australian climate – should give 156kts TAS and as little as 16 US galls/hr.

But being more realistic and accepting an OAT of +19C, the TAS jumps to as much as 157, with economy flow down to 14 US galls/hr.

Clean and dirty stalls followed the settings experiment (and Gulfstream claim their Cougar can span 800nm with reserves intact at 75 per cent power, 8500ft, or run for 1160nm at 45 per cent power).

The Cougar is cleared for stalls, chandelles and lazy eights. Stalls in both clean and dirty modes are announced by the tail buffet. In the test aircraft, a clean power-off stall was arrived at with 60kts indicated. Dirty, the aircraft dropped gently but definitely at 54 IAS. Height loss was about the book – between 180 and 200ft.

The single-engine stall is more definite, with both a pitch-down angle and roll. Gulfstream’s manual says that coupled with a height loss of up to 300ft, pitch-down could be up to 20 degrees, and roll up to 25 degrees.

Recovery in all but extremely light conditions in one-engine- situations doesn’t need operating engine power reduction.

Asymmetric flight in the Cougar is far from being as depressing as some pilots assert. It should be treated as the definite manoeuvre, drill and condition it is. The paramount point is that indicated airspeed must be kept above best r. o. c. speed (one engine out) of 85 knots.

In practising asymmetric flight in the Cougar, a simulated engine-out emergency can be set up by initiating a zero thrust condition; prop control retarded to the Feather detent (about 2000rpm) and throttle closed to 12in Hg manifold pressure, with full power applied to the “live” motor.

The test Cougar was flown with both engines shut down in turn. The shut-down drill after dead engine identification is throttle closed, propeller feathered, mixture to Idle Cut-Off, and cowl flap closed.

Then follow mags, alternator switches, fuel selector and auxiliary fuel pump – all OFF.

With either the left or right engine shut down, the Cougar’s “live” engine was given 26/2650 and maintained straight and level flight with ease, about five degrees of bank being fed in via trim into the operating engine’s direction.

Single-engine rate of climb was steady if unspectacular. It depends on weight, temperature and altitude. Single-engine service ceiling is carded at a scant 4900ft.

Re-starts after feathering were made easy in the test aircraft as unfeathering accumulators were fitted. In this case, the re-start drill was as per book – fuel selector ON, aux. fuel pump ON, throttle cranked about ½in. Mixture fully rich below 5000ft or matched with the “live” engine’s mixture setting at higher altitudes.

Pitch to high rpm, and the prop will begin windmilling at airspeeds above 95kts IAS. The starter can be used to aid unfeathering if needed.

Normal idle attained, aux. fuel pump OFF, alternator ON. The re-started engine should be warmed up at 15/2000.

The Cougar showed no vices during asymmetric turns or other normal manoeuvres.

En route to the Bankstown circuit, it was quite easy to let the Cougar off the leash and crank up into the yellow arc (160- 188kts IAS), proving that Gulfstream light twin is aerodynamically as clean as a whistle.

The airspeed indicator is clearly marked in arcs and radials, as follows: (All speeds indicated airspeed): Vne (red radial) 188. Vno (yellow arc) 160-188. Normal operating range (green arc) 71-160. Best r. o. c. speed, one engine inoperative (blue radial) 85. Full flap operating range (white arc) 63-110. Vmca (red radial) 61.

Descent is ideally at standard rate, with up to 188kts IAS in smooth air, 160kts IAS in rough air, and 120kts IAS in IuIbulence.

A flapless landing was decided on, to round off the evaluation. Base, wheels down and checked, was negotiating at 90kts IAS, 15/2200 set. Finals were made at an initial,11 85 knots indicated, touch occurring at 65 indicated with this nose wheel being lowered fairly smartly.

Mary O’Brien, who had taken over for the landing, filled in the evaluation with details of figures gleaned during her Cougar ferry from Savannah to Bankstown via the Atlantic route.

Averages logged during the 15,782nm flight from Boston included height (8000ft); settings (20. 5/2430), power percentage (63 per cent) and fuel consumption (14. 655 US gph).

In essence, the Cougar appears to be an ideal machine for short-medium haul work in the private/training sphere, its modest single-engine rate of climb being largely compensated for by Australia’s flat terrain – for the most part.

It represents good value at less than the dreaded $100,000 barrier.

Arguments against its engine-out climb performance – or lack of it – are at best academic. The object is surely to make certain such a condition does not come about.

The Piper Seminole

Like so many other successful types, the Piper Seminole PA44-180 is the result of an abandoned earlier project and amassed expertise gained on an earlier operational and saleable product.

The popular Twin Comanche was first introduced in 1963 and kept going.

A few years back, when the Big Three (Four, including Gulfstream nee Grumman) began filling in the hole between sophisticated singles and ditto twins, the Piper Aircraft Corporation started a new project in the bowels of Lock Haven, Pennsylvania.

They called it the PA-40 Arapaho, an update on the older Comanche.

Certificated, developed and ready for the world’s market, the Arapaho was held by Piper. Reason; a high projected market price.

And so the Seminole was conceived.

The aircraft is definitely kin to the Arrow, Archei and Warrior, although the Arrow must be considered the sire of this workmanlike and honest light twin.

Piper’s experience and genius were applied seriously to the Seminole; the result is what is technically known as a design balance – a measuring in carefully calculated quantities of efficiency, cost and comfort, flying performance and flying enjoyment.

The Seminole team took Piper’s established T-tail configuration and added it to what was basically an Arrow airframe. Two 180hp Lycomings were chosen to power this type, counter-rotating to eliminate torque and “critical engine” syndromes.

The T-tail established light and responsive control by increasing the effectiveness of the horizontal stabilator. It also lowered vibration and wingwash and cut cabin noise down.

Pitch and trim control was enhanced by the T-tail. The Seminole’s big rudder has been designed with an anti-servo rudder trim tab increasing rudder effectiveness and yaw control down to the stall.

Aerodynamically balanced ailerons were added to a tapered wing design copied from those highly successful departures from Piper’s old plank-form wings.

Testing proved the point that these added up to minimal drag coupled with quick response at cruise, plus positive roll control in slow flight.

Because the Seminole’s engines attach to the wings in the same spot where fuel tanks in the single are located, Lock Haven’s team decided to put the fuel somewhere else – in the engine nacelles, aft of the Lycomings.

The two 46-gall Imp bladder tanks housed in those positions have passed rigid FAR testing with ease during drop-tests.

Although the Seminole is born of the Arrow in basic fuselage concept, cosmetics have all but obliterated the family likeness.

The entire design has flair and an honest appearance echoed in subsequent testing. With Piper’s excellent external finish plus some brilliant designing in engine cowlings, a long fibreglass nose cone housing landing gear mechanism, combustion heater, battery and landing light, the Seminole is hard to fault – if the buyer went around looking for faults rather than attributes.

The wordy battle about the single-engine climb rate will no doubt rage for as long as there is both competition and partisan loyalty. The Seminole manual gives a single-engine climb rate of 217fpm, producing a gradient of about 159ft/nm.

In comparison, the Cougar’s latest manual amendment gives 200fpm, and the Duchess is manual-listed at 235fpm. Whichever way one regards this new generation of light twins, the cold fact emerges that none of them is startling in engine-out mode.

Inside the Seminole, cosmetics have been vastly improved over earlier light singles in the family. Seating is definitely contoured for anatomical comfort, back seat legroom is ample, fabrics are aesthetically pleasing and practical, and noise levels are low to a marked degree.

Currently marketed by Ansett General Aviation at Bankstown, the Piper Seminole has attracted more than an average share of interest since the first copy arrived around Christmas last year.

Department of Transport certification has been exhaustive on the type – and indeed on the entire range of light twins. In the Seminole’s case, the only restriction imposed by DoT has been the IFR weight limitation of 380016. Ansett General Aviation is marketing the Seminole with two first-priority targets in view; the IFR and twin-training sector, and the private owner market.

Prices are competitive; the type tested was selling for about $ 115,000 complete with a comprehensive panel; a very middle-of-the-road figure compared with the other two offerings in this particular range.

This price includes registration in Australia and full IFR configuration.

Ansett General Aviation made VH-TVP available for testing along with AGA’s Keith Robey. The aircraft had been on the Australian register in Normal Cat. since February this year and was the first of six now available to Australian buyers, or clients in P-NG or New Caledonia.

On walkround, the test aircraft showed points mentioned earlier in this report, plus a lot of minor and sensible cosmetic work including a centralised fuel drain system.

Inside, the Seminole’s panel is typical Piper handiwork – commonsense layout (and the left side cockpit switching was no snag, despite reports from the US on their accessibility), and in this particular copy a panel that housed VHF and HF comm. , VHF Nav. , glideslope, ADF, DME, marker and SSR, with an Altimatic IIIC autopilot.

Visibility over the long, sloping nose is excellent, and in other planes is without comparison in the range. Seating is anatomically thoughtful, back seat passengers having access to excellent light, visibility and air – and space.

The cabin width is 41. 5in in the Seminole with 36in seat-to-ceiling headroom.

Manual study before engines start produced the following vital stats. : Vne 202kts, normal operating speed 169kts. Vie gear extended 140kts IAS, gear retraction 109 IAS. Minimum Control Speed 56, single-engine best r.o.c. , 88.

The manual carried the stock wording that positive climb might be impossible on one engine in certain conditions of weight, temperature and other factors.

Start drill on the Seminole is standard; for each four-cylinder Lycoming 0-360-E1AD motor (180hp at 2700rpm) the sequence is Fuel ON, Mixture Rich, Throttle ¼in open, Prop Forward, Master ON, Fuel Pump ON, Ignition ON, Prime as required.

From the engine start it is obvious that the Seminole is a quiet aircraft. Decibels were the lowest in all flight and ground-handling phases, of all three light twins tested.

Ground handling is light on foot-loading, and definite in direction. At the run-up segment, magnetos are checked in standard fashion at 2000rpm, props are cycled at 1500rpm.

The test aircraft was well under gross – an estimated 3187Ib with gross standing at 3800Ib, giving a healthy margin of about 331Ib still to fill – on take-off.

With outside air temperature at + 21C and a relatively moderate load, the Seminole accelerated briskly. Tracking was almost taken for granted, thanks to counter-rotating propellers.

Progress built up sharply towards Vr, in this case, 70kts, with wheels off being initiated at 75 IAS.

Stabilator authority was at once apparent, the test aircraft popping sparrow-like off the runway under a firm backpressure.

Gear up was selected early to fall within Vie gear up limits of 109kts IAS. Despite the Seminole’s apparent positive incidence at rest, the take-off run in retrospect seemed almost at negative incidence, and some practice would be needed to milk the aircraft into flight.

The best rate of climb speed of 88kts IAS was set up, and the test Seminole notched an initial 1500fpm climb before settling back to a steady 1400fpm.

At 2000ft settings of 24/2400 were applied resulting in a steady 146kts TAS. This speed fluctuated between 150-160kts TAS during a steady run, and a climb rate of 1500fpm was held to 4000ft with the same settings.

Piper’s brochure figures are obviously conservative.

The aircraft proved stable in all planes, the lateral stability proving the point that fuel placement has lessened the wingtip weights to a marked degree. Inboard-retracting main wheels help lessen wing structure outboard of the nacelles.

Stalls were performed as a matter of course; in clean condition, considerable airframe buffet heralded a mild break at between 44kts-48kts IAS (an average T AS of S0kts after temperature correction).

In gear down, flaps down mode, the Seminole stalled after significant buffeting at between 42-44kts IAS (an average of 46kts TAS). There are no surprises in the stall, no hidden tricks. Piper’s manual lists dean stalls at 57kts in IAS conditions, and dirty stalls at 59kts.

A session of more general airwork before testing engine-out flight re-stated Piper’s claim for perfectly harmonised controls – and fully justified it.

The single-engine flight was significant in its routine. Piper has sensibly not over-emphasised their claims in this mode, knowing that to underline any statement would be rather like throwing a stone in a glass house.

Single-engine rate of climb at gross is 217fpm, says the book. The test aircraft was taken down to 3700ft, one engine shut down and prop feathered, and the aircraft climbed up to 4000ft in less than 60 seconds without slowing down to the recommended 88 knots.

Even allowing for the relatively light condition, that’s a great advertisement for the Piper Seminole.

Yaw in the climb was represented with the ball being about ½in to ¾in out of centre and about three to five degrees of bank trimmed in to lift the “dead” wing.

Single engine service ceiling is booked at 5250ft at gross. In a transit cruise, both engines working, the Seminole appears to perform best between 6000ft and 9000ft with 65 per cent power, for about 155 knots. Fuel flow should be expected to average 14. 2 galls Imp/hr at best economy mixture settings.

On arrival at the destination, gear can be lowered at 140kts IAS, with 88 knots eroding to 75 over the fence to cut out any suggestion of float. The three-stage flap adjustment, made through a manual lever, gives 10, 25 and 40 degrees of flappage.

Again, Piper’s T-tail irons out pitch changes during undercarriage or flap extension.

Ground run is listed at 183ft, and characteristics shown during this test prove the Seminole can do it. However, on the evaluation landing only 10 degrees of flap were used and the Seminole allowed to run.

Overall impression of this evaluation was that Piper have a fine light twin in the Seminole. Handling qualities, noise levels, pilot workload and passenger comfort are all superior to other contenders in this bracket.

The Seminole’s unique built-in reliability and steadiness should stand it in good stead when multi-engine training and IFR platforms are considered by flight training establishments in Australia.

Data Box:

Piper PA 44-180 Seminole.

Twin-engine light aircraft, low wing, retractable undercarriage trainer-private owner type.

Price of aircraft tested, $A 115,000, on Australian register and fully IFR. Aircraft evaluated supplied by Ansett General Aviation, Bankstown, NSW, phone 709 6666.

Specifications:

Engines, two Lycoming 0-360-E1AD, 180hp at 2700rpm, recommended TBO 2000 hours.

Weights: Gross 380016. Standard empty, 240616. Useful load, 13941b.

Wings:

Wing section NACA 652-415. Wing area 180 sq ft.

Loading, 21. 11 lb/sq ft. Power loading 10. 5516/hp.

Baggage:

Aft compartment 2001b.

Dimensions:

Wingspan 38. 55ft. Length, 27. 6ft. Height 8. 5ft. Cabin length (panel-rear bulkhead) 97in. Cabin width 41. 5in. Cabin height 49in. Wheelbase 8. 47ft.

Fuel capacity:

Standard 110 galls US. Usable, 108 galls US.

Performance:

(All at 38001b gross); max speed 168kts, 2700rpm at sea level ISA conditions. Cruise speeds TAS, 75 per cent power 2400 rpm 7000ft – best power 164kts, best economy 161kts. 65 per cent power 2400rpm 10,700ft – best power 159kts, best economy 157kts.

Fifty-five per cent power 2400rpm 14,500ft – best power 151 kts, best economy 149kts.

Stall:

Full flap (40 degrees) 55kts IAS. Flaps up 57kts IAS.

Cruise range:

75 per cent power, 2400rpm at 7000ft, best power 690nm, best economy 790nm. At 55 per cent power, 2400rpm at 14,500ft, best power 730nm, best economy 880nm.

Climb rate:

(Sea level, gross weight), two engines 1340fpm, one engine 217fpm. Service ceiling, two engines 17,100ft, one engine 4100ft. Absolute ceiling, two engines 18,600ft, one engine 5250ft.

Take-off distance:

Ground run 880ft, over 50ft obstacle 1400ft.

Landing distance:

Ground roll 383ft, over 50ft obstacle 1190ft.

Accelerate-Stop distance:

Sea level, nil wind, ISA, with heavy duty brakes, 25 degree flap, 2070ft.

Beechcraft Duchess

The Beech Aircraft Corporation Model 76 – alias the Duchess – is being distributed through Beech Aero Centers in North America as the principal multi-engine training aircraft for them.

Superior low-speed handling qualities and operating ease, two of Beech’s design objectives in evolving the Duchess, are among the main factors governing this decision.

Duchesses are now in Australia, the first being nearly a year old in its new country. Hawker Pacific Beechcraft distributors based at Bankstown, are already marketing the Duchess as an ideal multi-engine training machine.

NSW-based Navair has been one of the first customers, putting a Duchess on the line as a front-line machine in Navair’s IFR training line-up. Others include Civil Flying Services in Victoria and Beechair in South Australia.

Hawker Pacific hasn’t been idle in the private owner market, and a Mackay, Queensland, Beechcraft owner now has a Duchess.

The Beechcraft Duchess, born nearly five years ago after feasibility studies on the basic Sierra design, is Beech Aircraft Corporation’s first light twin entry on the world’s market since the little Travel Air ceased production in 1965.

The first design to emerge WAS basically a Sierra with two engines and a Big-T empennage; the project, PD289, was not an instant success.

It had a brace of 160 engines, a near-standard Sierra fuselage and Beech’s then-common thick wing, plus a lot of commonality with Beech’s current light aircraft types. But it was obvious the design had a long way to go in a short time – Grumman and Piper, plus Cessna, were also developing their own transitional twin.

The first change at Wichita was to re-engine the design with mirror-moulded Lycoming 0-360s giving 40 extra horsepower and powering inboard-turning propellers.

The design aerofoil was modified inboard of the nacelles; several engine mods for cold-weather work were engineered, among them being channelling intake air through the hot oil sump, and siting air intakes inside the nacelles.

The T-tail was specifically made for the Duchess. Made of a far stiffer material than the Sierra, it uses a large amount of bonding.

The Duchess’s undercarriage mains were designed to tuck up inward, unlike the Sierra, with fuel tanks outboard of the engine housings.

Although the knee-action design was retained, the Duchess’s legs are oleos – unlike Sierra’s rubber doughnut shock.

Wing area was increased from the basic Project PD 289 design to 181 sq ft; the combination of added power and wing area meant a more useful load.

One Sierra heritage thankfully retained has been the number of doors, two each side for the front seats, and a jumbo-size “cargo” door port side aft. Despite the after door retention, Beech list the Duchess strictly as a four-seater.

Other mods introduced to produce the current Duchess have included enlarged aileron travel and size.

In testing the pre-production Duchess, Beech gathered some interesting data on T-tails. Elevator authority was such that excessive nose-up attitudes appeared prior to a power-on stall break, in the 160hp Project PD 289 aircraft.

Fuselage strakes were tried, but Beech eventually rejected them as being unsightly. The fitting of 180hp engines and inward-turning props arrived just in time.

And so the Duchess emerged from Beech’s plant, new in most respects and a serious contender for yet another major contest in the world’s customer stakes.

First deliveries were made in, March last year, with Hawker Pacific adding its name to the lists. Hawker Pac’s first Duchess arrived last October amid a welter of interest from potential buyers.

The Australian distributor is holding orders for or has sold at least five Duchesses at the time of writing anc;l is confident of coping with a far bigger Australia allocation.

Most clients have read the fine print about single-engine climb rate of all three current transitional twins on the Australian market, and realised that operating weight has a lot to do with figures claimed.

Values have narrowed down to realistic range, performance and workload, and the Duchess acquits itself very creditably in these departments.

Hawker Pacific’s fourth aircraft to land in Australia, a trade-plated VH-DHW for our evaluation, was provided along with chief pilot Peter Dodge. A full workout of this aesthetically pleasing little twin added time to the 76 hours it had when the test began.

The aircraft came out of the Wichita plant as ME 65. As flown she was selling at $125,080, Australian C of A and boasting a well-filled panel which included VHF Com. , ADF, transponder, glideslope, audio control panel with market beacon, HF and a host of other el. ectronics. – -my first acquaintance with Delta Hotel Whisky emphasized the fact that just about the only real commonality with the Sierra has been the interior.

The Duchess as flown in this test has a light, airy feel about its interior, but back-seat passengers could be confronted with a very real problem in legroom – completely out of kilter with the enormous baggage space behind the rear seats.

Loading the Duchess under anything but extreme circumstances unlikely to appear to one in a thousand pilots presents no problem. With no baggage area in the nose and a 200Ib aft baggage compartment limitation, permutations of p. o. b. and baggage plus fuel almost invariably fall well within c. of g. parameters.

The panel layout is sensible, typically Beech; flight instrument to the left, engine cluster midships and avionics right.

The excellent seating arrangements optically lower the high coaming to give admirable viewing.

Normally aspirated engine start is standard drill. On taxi, ground handling qualities are more than just good, with low foot-loading. Asymmetric power application is unnecessary in all but the tightest of corners.

Beech claims a turning circle (at the wingtips) of 27ft using brakes and power – if you have to.

On priming the engines; the Duchess has push-tooperate primers mounted under the combination magneto switch/starters. Thus one can prime while starting. Cold starts take an average five to seven priming seconds, hot starts none at all.

At the holding point the test Duchess weighed-in at an estimated 3527Ib – three passengers and full fuel, and well under the max take-off limit of 3900Ib. Outside air temperature was a hot +31C.

Minimum control speed in the Duchess is listed at 65 knots indicated, with stall at 60, flaps down. Acceleration was steady rather than spectacular but built up fast near Vr, 70 indicated in this case.

Take-off was made at 75kts IAS, with nil flap, in about 1200ft (performance data lists the distance at 1017ft under ISA condition, max take-off weight).

The take-off run was marked by complete absence of torque swing, thanks to inboard-turning propellers.

Undercarriage retraction was initiated as soon as positive climb was established. Gear retraction speed is carded at 112 knots to avoid excessive loads on the forward-retracting nose wheel.

Initial r. o. c. was logged at 800fpm, increasing to a steady 1000fpm after gear retraction was completed in eight seconds and settings adjusted to 25/2500. International Standard Atmosphere readings are listed as r. o. c. 1248fpm at sea level, at max gross.

Best rate of climb is 85 knots, according to the manual.

The test aircraft was climbed at the recommended setting of 25/2500 with 100 knots showing, giving an ample 1000fpm without cutting down on visibility.

The Duchess under test showed her willingness, lack of vices and tractability right from wheels off and throughout the check. Visibility in normal flight attitude proved very good, ventilation likewise.

The only consistent snag was in the back seat department, where the third passenger had continuous trouble in finding a comfortable place to put his legs. Noise level in his department and in the front seats was not unduly low, but acceptable.

Various combinations were applied to the test aircraft, and in all cases bettered book speeds – some only marginally, but definitely.

With 24/2700 showing at 6000ft, a T AS of 166 was arrived at with fuel flow (US gallons) of 11. 3 per hour/engine. This was carded as 80 per cent power.

Seventy-five per cent power resulted in 24/2500, 162kts TAS and fuel flow per side of 21 US gallons/hr.

The margin between 65 and 70 per cent power at 6000ft proved one of the most satisfying readings; 24/2300, T AS of 157 knots and fuel flow of 19. 6 US gph/total.

The manual lists economy-long range settings and readings as follows: With 20/2300 applied, at 6000 feet you should expect a true air speed of 140 knots, with total fuel flow/hour of 15 US gallons.

These settings should take you (in ISA conditions) at least 780 nautical miles.

Asymmetric flying produced no unpleasant surprises, although the single-engine rate of climb at sea level of 235fpm was somewhat lacking at 4000ft.

After standard shut-down drill and putting 25/2650 on the “live” engine’s gauges, a rate of climb was certainly established.

But it was far from the carded reading. Single-engine service ceiling is listed at 6170ft, whence the beast arrives at 50fpm.

Any yaw is easily trimmed out in asymmetric work, and turns into and out of the “dead” motor accomplished with ease, with all due care taken en route.

Recommended rate of climb speed on one engine is the same as on two – 85kts IAS, satisfyingly above the Vmc of 65 knots.

Safe single-engine speed in the Duchess, according to Beech figures, is established at 72 knots, and that’s about as slow as any instructor should let his student fly on one engine.

Stalls are heralded by ample buffet plus aural warning given through either the clean mode vane or dirty condition vane mounted on the wing. Breaks were straight ahead in all the test stalls and recovery rapid with angle-of-attack reduction.

For the record, stalls are booked as follows: Flaps up, power off; 70 knots.

Flaps and gear down, power off; 60 knots.

Temperature-corrected true air speeds notched during the evaluation were handsomely better than book. Clean, stall occurred at 60 knots, with dirty condition stalls happening at a shade under 54 knots T AS.

Circuits work is a pleasure in the Duchess, with final approach speed being an ideal 75 knots over the fence. The big trailing beam undercarriage is forgiving enough – a firm arrival in a stiff crosswind caused the test aircraft to crow-hop reprovingly but settle down quickly into a safe progession.

Normal landings in ISA condition could take up to 1000 feet ground roll. Elevator control is such that the classic nose-up arrival can be safely maintained for some distance down the runway on arrival.

Although the Duchess is an aerodynamic masterpiece, slowing the aircraft down prior to circuit speed is easily accomplished with gear extension speed booked at a healthy 140 knots indicated. Flaps can be operated at 110kts IAS.

Hawker Pacific takes particular pride in displaying DOCs to prospective clients. Estimated direct hourly costs (taking into consideration the 1500hr/TBO figure given in the sum, and 1000hr prop overhaul) are worked out at $27. 72.

Total operating costs work out to $31. 55 per hour with 1000 hours flown per year. In actual fact, Hawker Pacific’s figures show direct hourly costs static, with annual fixed costs sliding down as utilisation increases.

Hawker Pac’s executives maintain these figures – or an average of them, reached by operators – should remain steady for quite some time, in the face of possible fuel hikes, wages and operating costs, etc.

Summary

Evaluating these three aircraft naturally posed the question of which aircraft wins the Light Twin Stakes as far as Australian application is concerned.

The answer is at best an academic one; each aircraft has good, bad and indifferent features. None of them has a startling single-engine climb performance, which is what most pilots wanted to know for reasons best known to themselves.

For personal choice, I found the Seminole to be the most satisfactory all-rounder in terms of accommodation, noise levels, pilot workload including control forces, and cabin environment.

The choice was confirmed by culling salient features from the respective manuals, adding an Environment section and giving each section’s readings a points system.

Second choice was the Duchess. The Cougar notched a close third placing according to the readings. The Cougar was ahead on price, DOCs and TOCs based on 600 hours’ use annually, and tankage, wing area and loadings.

The Duchess forged ahead on factors including gross weight at take-off, cabin width, max sea level speed, cruise at 75 per cent, service ceiling, and climb rate.

The Seminole notched first place with wingspan, take-off and landing distance, stall and Vmc speeds, and scored heavily in cabin seating, noise levels, workload impositions including control forces, and overall cabin environment.

Consistent second placings for the Seminole added up to a healthy margin over the Duchess.

If one disregards the Cougar in terms of a smaller HP aircraft and chooses to slug it out between the Duchess and Seminole, the Duchess won on gross weight, useful load, wing area, cabin width, max speed, cruise at 75 per cent power, service ceiling on one/two engines and climb rate.

The Seminole was out in front on price, wing and power loadings, cabin length and height, take-off and landing distance, clean and dirty stall speeds and Vmc speed, cabin seating (front and rear), noise levels, pilot workload reduction and cabin environment.

This is how the respective test aircraft stacked up when manual figures were applied, plus an Environment Section’s impartial markings:

(All figures, including prices, correct at time of writing. Manual amendments checked at time of writing.)