Acclaim

The highest I’d previously climbed in a piston single was 21,500ft, when I broke a class altitude record in my little Volkswagen powered Druine Turbulent. This time I was going much faster, and in enormously greater comfort, surrounded by the Acclaim’s warm golden interior and sumptuously cushioned in a deeply upholstered leather armchair, with tinted windows to keep out the harsh, high altitude sunlight, and cosseted from the biting -35°C cold outside by the Mooney’s effective cabin heater. This gets its hot air as a bleed from the dual intercoolers on that big six cylinder TCM motor droning away gently out in front. And the twin turbochargers served by those dual intercoolers are the reason this Mooney can climb so high and cruise so fast.

Our indicated fuel burn was down at 22 US gallons per hour (82 litres per hour), so we were getting a fuel economy of 12. 5nm per US gallon (indicated). That is 3. 3nm per litre (or in car terms 16. 35 litres per 100km) which, although admittedly thirsty, is nevertheless amazingly good for a hulking nine litre engine, and particularly since we were belting along at a whopping 510km/h! Try going that fast in “

Try going that fast in any other kind of vehicle – any vehicle at all – and I guarantee you will get nothing like this kind of economy.

” any other kind of vehicle – any vehicle at all – and I guarantee you will get nothing like this kind of economy.

Okay, so our TAS was actually 233kt or 430km/h, and we were covering the ground particularly quickly because we had a 40kt tailwind, but one huge advantage of this class of aircraft is that, with its stratospheric 25,000ft ceiling, you can climb to seek out the most favourable winds, however high they might be, and even take advantage of the lower levels of a jetstream if you can find one.

The Acclaim’s integrated Garmin EFIS makes both navigation and systems management easy, and gives its pilot all the supplementary information he could possibly need, while the most capable autopilot I have ever encountered in a piston single eases your load by doing the donkey work while you make strategic decisions, relax, run back your seat and stretch out your legs – something that it’s just not possible to do in most of the competition.

All this capability is the result of decades of evolution, for structurally the Acclaim is pretty much like all the other 20th and 21st Century Mooneys. Incidentally, the formula works well, and these airframes are strong, for I have read that the whole Mooney family has only ever suffered two inflight structural failures, both after loss of control in thunderstorms.

The Acclaim retains that 45cm longer fuselage originally introduced 20 years ago for the ill-starred Porsche-engined PFM. Giving rear passengers 10cm more leg room and longer,panoramic windows, this has also increased the baggage compartment’s volume (although its 54kg weight limit remains). There are also all the other side benefits of a fuselage stretch: starting with the bigger windows and more pleasing lines, but including improved pitch and yaw stability and better elevator control in the landing flare.

Because it has become a consistent winner, Art Mooney’s original formula has been changed little over more than six decades.

His namesake designs fly on an efficient, wide span, high aspect ratio, low drag, NACA 632-215/641-412 laminar flow wing which has a tip to tip one-piece spar and is flush riveted for minimal drag over the first third of its chord (as is the fuselage). Also to minimise drag, the skins are wrapped right around from the rear spar’s bottom to its top, so there are no joins along the forward third of the chord.

Skin thickness increases towards the roots to augment strength and rigidity. The wing’s leading edges and those of all the tail surfaces are straight, although taper on the trailing edges gives the visual impression of forward sweep.

The Acclaim has new enlarged, upswept wing tips to reduce induced drag. Said to act like mini winglets, these are apparently particularly effective in the low IAS, high altitude environment the Acclaim calls home, although to my eyes their appearance (and quite possibly their aerodynamics) was spoilt by the ugly lump of wing-tip navigation and recognition lights tacked on to their outboard edges. The former fuselage mounted red rotating beacon has been replaced by a strobe light in the rudder.

Alone among their class, Mooneys can be approved for flight in known icing conditions, using the optional glycol-exuding TKS leadingedge de-icing. All control surfaces are balanced, carefully faired and gap-sealed, with the exception of the long, slim flaps, whose seals had been removed some time ago to lower stall speeds to the maximum permitted 61kt.

Dual inboard stall strips on each leading edge presumably help with the low speed behaviour, while twin xenon landing and taxi lights in each leading edge and strong white wing tip recognition lights provide plenty of illumination.

MOONEY M20TN
ACCLAIM

Powerplant
Teledyne Continental
TSIO-550-G(1)
fuel-injected, dual
turbocharged, dual
intercooled, air-cooled
flat-six, producing 280hp
(209kW) at 2500 rpm.
TBO 2000 hrs. Propeller:
Three-blade constantspeed
Hartzell PHCJ3YF-
1RF/F7693DF-2.
Performance:
Max level speed 188kt
Max cruise 237kt
Economy cruise 153kt
Stall, clean 66kt
Stall, full flap & gear
59kt
Max range 1445nm
Max range (optional
tanks) 1840nm
Max endurance 9.7hr
SL climb 1240 ft/min
Service ceiling 20,000ft
Takeoff dist to 15m
700m
Landing dist from 50ft
62m
Weights
(test aircraft)
Equipped empty 1093kg
Max t/o 1528kg
Max landing 1452kg
Useful load 435kg
Useable fuel 390 lit
Max baggage 54kg
Load factors +3.8/-2g
Dimensions
Length 8.15m
Height 2.54m
Wing span 11.00m
Wing area 16.2m2
Manufacturer
Mooney Airplane
Company
www.mooney.com
Price from US$579,000

The otherwise sophisticated Acclaim’s landing gear remains the familiar low maintenance (but comparatively low absorption) trailing link, rubber-in-compression affair, with all three units mechanically interlinked so they extend and retract together. The nose wheel has twin parallel doors and retracts rearwards, while the main legs retract inwards to be covered by three low drag interlinked doors.

The innermost of these has been bulged since the late ’90s as part of Mooney’s continuing quest to minimise drag and achieve maximum cruise speeds.

Every member of the big Mooney family has bearing mounted pushrod operated controls, making them light to move on the ground, with minimal friction and break out forces. Even with the yokes being restricted to just 45 degrees of travel at full throw to keep them (just) clear of the front occupants’ thighs, the high geared ailerons are surprisingly easy to move. The sole unusual feature now sported by all Mooneys are the scissor style electrical speedbrakes situated at one-third span and two-thirds chord on each wing. I was told the Acclaim’s airbrakes are taller but slightly narrower then the Ovation’s, although I’m not sure why.

All Mooneys have huge wet wing fuel tanks, in this case holding a total of up to 360 litres of which only 337 litres is useable. Long range 492 litre tanks are an option. Sensible external mechanical fuel gauges above the inner wings allow accurate partial loads to be uplifted (and can be viewed from the cockpit in flight in an emergency). There are also metal tabs in the tanks’ filler necks, so your refueler can load just 340 litres, which is what we had for our flight.

This is important because, like any other aeroplane, the Acclaim’s available load is limited by its approved maximum weights – only in this case, more so than many. Unfortunately those turbochargers, intercoolers and the necessary but inevitably heavy oxygen bottle have increased its basic airframe weight byaround 25kg, reducing payload by a similar amount. So, while this example’s comprehensive avionics and standard 77 cubic inch oxygen bottle take its empty weight to 1093kg, and it can still carry four full-sized adults, under those conditions it would be limited to fuel for less than two hours flying.

However, filling both tanks to the brim reduces its payload to 158kg, meaning a 85kg male and an 65kg female could only take an 8kg cabin bag between them.

And then they would be committed to flying for an hour or more to get down to the 1452kg landing weight, although of course they could cover up to 1400nm or more. If you choose the optional larger 115 cubic inch oxygen bottle (because far from every Australian airport has oxygen recharging facilities) and fit air conditioning, you could lose another 50kg of payload, while the de-icing kit knocks off another 17kg, plus up to another 25kg of fluid. Buy the lot and you’d better not weigh more than 66. 5kg yourself, or you can’t fill the tanks! You can ring the changes however you like, but this is a limited aeroplane, so you cannot just fill the seats and tanks and go! For our flight, two up and with ‘tabs’ fuel, we weighed around 1525kg, or just three kilos below the maximum, and with our C of G close to the forward limit.

The big difference between the Acclaim and its other Mooney siblings is its engine. Producing at least 300hp (224kW) in some other aircraft installations, this powerful nine-litre TSIO-550 was de-rated to 280hp (209kW) at sea level (by limiting rpm to 2500) because the aeroplane runs out of rudder authority at higher powers. Although it uses a comparatively low compression ratio of 7. 5 to one, the engine is fitted with twin turbochargers and dual intercoolers to provide turbo normalising (thus the TN designation suffix), so it generates maximum power right up to 20,000ft.

The lower stresses resulting from the reduced compression ratio and limited rpm improve the engine’s reliability, so TCM has increased its TBO from 1800 to 2000 hours in this application, with a three year warranty.

A dual-pipe cross over exhaust manifold gives minimum back pressure for maximum efficiency, smoothness, and even temperatures without cowl flaps.

Indeed, thanks to its good breathing and those efficient pressure cowlings, according to Mooney’s American demonstration pilot Corbin Hallaran, this powerplant almost never runs hot, and an oil cooler blanking plate is supplied to keep the gauges up in the green when necessary.

There are no pesky, unreliable vacuum pumps in this all-electric aeroplane.

Instead, the primary direct gear drive 100 amp 28 volt alternator charges two switchable 10 amp hour batteries in the rear fuselage (to keep the C of G in the right place). The spare battery is available when needed at the flick of a switch, and provides two safe hours of avionics use in an emergency. Most operators will routinely switch from one battery to the other on alternate legs, to keep them both in good condition. On the rear of the engine, driven from the accessory case gears, is a second, back-up, 20 amp hour alternator.

The Acclaim’s imposing, 76in three bladed Hartzell Scimitar propeller has a slightly larger diameter than the Ovation’s 73in McCauley, somewhat reducing its loaded ground clearance to a still acceptable, but perhaps rather tight 23cm. A big, gleaming polished aluminium spinner adds that finishing touch, while softer rubber engine mounts help insulate the cabin from any remaining vibration.

This powerful engine’s beautifully sculpted lightweight graphite composite (carbon fibre) cowlings slope gently forward from the windscreen to generous circular cooling inlets. They are not marred by the fuel injectors’ air intake, which is neatly positioned behind and below the spinner. Unfortunately, a small hinged flap over the dipstick makes it impossible to inspect the tightly packed engine compartment without removing the entire top half cowl. The Acclaim’s firewall has been widened 2. 5cm or so over earlier models, to fair the cowling cheeks with its fuselage sides and give the aeroplane a nicely aerodynamic, gently curved waistline, while also providing the cabin’s occupants with slightly more elbow room.

The entire forward fuselage skin is not load bearing, but covers a strong, crush resistant 4130 chrome molybdenum steel tube cage that surrounds and protects the occupants. This space frame is still mated to a conventional all-aluminium semi-monocoque aft fuselage carrying the trademark all-pivoting tail unit.

With straight leading edges and forward swept trailing edges, this tail is far more efficient, and so can have a much smaller area than those of all the competition.

Without exception, these are swept back for mere aesthetic reasons, mimicking those on transonic aeroplanes, which have to be swept to combat Mach effects, despite the disadvantages. The Mooney’s whole tail tips back and forth, run either by a large, low geared floor mounted manual trim wheel between the pilots, or an equally low geared electric motoroperated by conventional yoke mounted elevator trim switches.

A substantial, well faired fixed step allows an easy hop on to the low wing root’s wide non slip walkway. The cabin’s single right side door has a grab handle on its forward pillar, aiding entry to the front seats, which have to be run forward, with their backs lowered, for a rather less easy access to the rear ones.

At 1. 04 metres, the cabin is a couple of centimetres wider than in older models, and its new, light cream, moulded plastic side-wall panels improve the appearance and disguise the underlying tubular cage while allowing slightly more elbow room.

The Acclaim’s headliner is fawn wool, the taupe carpets are thick, and the upholstery is well padded champagne leather. The comfortable front seats are adjustable for height, rake and fore-andaft to cater for a variety of leg lengths (and to stretch out in flight), although in the aftermost positions the longer-limbed suffer further restriction of their already limited forward view. The long, narrow foot-wells match the aeroplane’s sports car like low ground clearance, as does having one’s head occasionally brush the ceiling. All occupants have lap and diagonal inertia reel seatbelts, the pilots’ incorporating airbags as standard, while these are also optional for the rear seat passengers.

The broad instrument panel is a pleasant light cream colour, and is mostly taken up with the two large, horizontally orientated Garmin G 1000 EFIS screens.

Over on its right margin, and in a short column above one another, are the three analogue standby instruments of ASI, battery powered artificial horizon and altimeter, looking positively archaic in this otherwise clean, modern cockpit.

The wet (standby) compass is bolted to a tubular member in the centre of the windscreen that forms part of the cabin’s structure and makes a useful handhold for entry, exit and seat adjustment. At the far right, and rather out of the pilot’s reach, is the circuit breaker panel. Black lines surround two groups of these breakers, depicting those services that remain after the load shedding button is pushed in the event of primary alternator failure.

The left EFIS screen displays all the normal flight instrument information, using the standard layout of horizon in the middle, flanked by airspeed on the left, altitude with VSI on the right, and a compass rose at the bottom. Navaid frequencies are arrayed across the top, and a very useful column down the left hand side displays manifold pressure, engine rpm, fuel quantity, fuel flow, oil pressure, oil temperature, turbocharger inlet temperature, cylinder head temperature, electrical volts and amps plus (uniquely) the flap, stabilizer and rudder trim positions. TAS and OAT are alongside, and the ASI tape is red below the stall speed, white to the flap limit speed, and yellow above the 174 knot Vmo, with a red line at Vne (194kt). The speed tape also portrays Vr (59kt), Vx (85kt) and the best climb rate or Vy speed of 104kt, which we manually reset to 120 for our planned cruise climb.

Autopilot and flight director modes are displayed along the screen’s bottom margin, while its black surround holds the knobs for tuning and setting volume on both nav and comm radios, setting the heading and course bugs, adjusting the cleared altitude (with thousands of ft per click on the outer ring, hundreds on the inner), altimeter setting and has the transponder numeral buttons along the bottom. A neat box in the screen’s bottom right corner is captioned ALERTS.

Interrogating this tells you when you are approaching or in airspace, approaching a waypoint, time to change tanks, and presumably several other useful little reminders. There is also an instantaneous wind vector, with its arrow showing the wind direction and numerals for its strength.

The right screen contains all the navigation functions, primarily supplied by AHRS and dual GPSs, but retainsthat useful column of engine and system readouts down its left edge. Among the additional selectable (and optional) information are: all other airways, high terrain contours provided by the enhanced GPWS, and TIS (Traffic Information System) sensed traffic. Instantaneous weather information is also available in the USA, but not yet here. The standard avionics fit includes dual VHF nav comms and 130 XM radio channels but no ADF, and the ELT works on 406 MHz. Having such a modern, paperless cockpit, naturally the Acclaim’s checklists also appear on the screens.

Unfortunately, the Acclaim’s light switches have been banished to that bane of bi-focal-wearers, an overhead panel.

This is totally unnecessary and counter productive, since there is plenty of room for them among the wide open spaces under and around the Garmin screens.

The landing gear switch is set in mid-panel, just below and to the right of where the left yoke’s skinny column protrudes from the panel. Since all three wheels are mechanically interconnected, the landing gear down indication is just a single green down caption (plus an amber unsafe light) on the 16 light annunciator set immediately above the right EFIS screen. These are supplemented by what Corby called ‘the football’ – a lighted oval window in the floor between the front seats, in which two stripes align when the wheels are down and locked.

The three position preset flap switch is well separated, across on the right of a lower vertical sub panel with the three primary engine controls’ vernier plungers.

Above the throttle are the electric rudder trim’s split horizontal rocker switches, plus other electrical rocker switches for autopilot power and the two fuel pumps (one of which is red and guarded), while the master, key operated rotary magneto/ starter switch, alternator field, battery selector and emergency busbar switches are on the panel’s far left. The oxygen valve knob is on the sidewall by the pilot’s left knee (and, unusually for a gas, this turns clockwise to start the flow going).

Below the panel’s centre are four neat but unusual, sliding, rectangular, pull-out controls for windscreen defrost, cabin heat, cabin vent and the parking brake valve. Below them is the heater’s hot air outlet, and below that a pair of cup holders. On the floor ahead of the right seat is a ring pull to operate the fuel drains, while between the front seats are the three position (left/right/emergency off) fuel selector, the stabiliser trim hand wheel and the emergency landing gear mechanism. The pitot static system’s drains are outside, at the wing roots.

The left yoke carries buttons for radio transmit, autopilot disconnect, control wheel steering and the airbrakes (one push and they extend, the next retracts them, both in little more than one second), the split electric pitch trim switch and a transponder ident button.

Padded leather yokes are a sumptuous option, while the previously optional Precise Flight airbrakes are now standard Mooney equipment.

The rear seat passengers will find it slightly more difficult to board, while The brakes are comfortably progressive, and the steering is light and nicely geared, but this aeroplane does not have a particularly tight turning circle, and has the odd characteristic of turning on a much tighter radius to the right than to the left because the nosewheel swings through 13 degrees one way and only eleven the other (although I don’t know why). This means that, while it describes a reasonable forty foot circle to the right, it makes a rather wide 48 foot turn to the left, although applying a little power as you lead into the turn can help a lot.

You might expect the short travel, rubber doughnut suspension to be harsh and stiff, but it was not, and gave us a comfortable ride at both Jandakot and the less level Serpentine. The long side windows make visibility better than usual over one’s shoulder, which is very useful both for taxying and the elevator control check.

Making our first takeoff from Jandakot’s Runway 06L with the handbook’s recommended approach flap (10 degrees) and full right rudder trim in a temperature of 22°C, I depressed the throttle’s vernier plunger and gently eased the knob forwards, keeping one eye on the centreline and the other on the manifold pressure gauge to modulate our power at 33. 5 inches or slightly less.

The aeroplane accelerated well, with that engine quickly losing its Harley note and sounding more and more sweet and powerful as its volume swelled while I opened the throttle and the power built.

Expecting to need lots of right rudder, I was pleasantly surprised that, with our trim setting, hardly any was necessary. As the engine peaked at around 33 inches our speed built through 60kt and I reasoned that was quite sufficient power, so I let go of the throttle and returned both hands to the yoke to ease us carefully off the ground.

The elevator did seem a little heavy, but nevertheless we lifted off cleanly at 70kt after a positive rotation to hold the far end of the cowling just below the visual horizon. Because of my slow and cautious application of power, and despite our 5kt headwind, we probably used at least two-thirds of the runway’s 1400m length, although the manual suggested a 450m ground roll in these conditions.

Lifting my toes up the pedals to dab the brakes, I flicked up the neat landing gear switch. Gear retraction was almost Bonanza quick, and caused no noticeable pitch change. Retracting the flaps at 300ft, again I felt very little pitch change, any there was soon being blipped away with the electric trim switch as we accelerated to Corby’s recommended 120kt climb speed.

In this configuration, with an eight degree nose up pitch attitude we achieved an impressive 1400ft/min at the expense of a 29USgal/hr (110 lit/hr) fuel burn.

Of course, since the engine is turbo normalised, we held that impressive climb rate all the way up to 20,000ft, with only occasional small adjusting twists of the throttle knob needed to keep the power at precisely 33. 5 inches on the digital EFIS read out. From FL 200 to FL 250 we climbed at a reduced but still impressive rate, gradually tapering off to around 1000ft per minute.

Feeling out the Acclaim’s controls on the way up, I found it a trifle heavy in roll (though perhaps not as bad as in the earlier, short bodied models), reasonable in pitch, and fairly light in yaw. Its rollrate may be a trifle ponderous, but little rudder is needed for coordination, and almost none at cruise speeds, with only gentle squeezes warranted below 100kt IAS. Although, in comparison to some more recent American four-seat designs, the Acclaim’s control authority is noticeably limited in all axes, its controls were certainly good enough for the accurate close formation flying we conducted later.

Its stability is good in all axes too, especially in yaw, so it exhibits none of the tail wagging demonstrated by the old V‑tailed Bonanzas and some earlier Mooneys. Visibility is not superb, because of the small round-topped windscreen and its thick pillars, but more than adequate for me to indicate a few local points of interest to our American visitor as we zoomed across the countryside while climbing up to the Acclaim’s preferred cruise altitude of 25,000ft.

Passing 10,000ft, I changed both our altimeters from QNH to the standard setting of 1013 HPa, and leaned down and opened the sidewall oxygen valve, while Corby reached behind for our oxygen masks. To don mine, I switched on the autopilot and pressed the flight level change (FLC) switch, which couples it to the ASI to fly a fixed IAS. Once Corby’s mask was similarly fitted, he had fully opened the two individual in line taps, and we had both checked our flow as being satisfactory, I was able to disengage the autopilot again and enjoy flying this sleek, stable, fast thoroughbred in its climb to altitude.

A little later, at 18,000ft, we switched on the fuel pump, to purge the system of possible vapour locks and ensure an uninterrupted supply in the rarefied upper atmosphere. At no time during our climb did the engine’s cylinder head temperatures rise above 360 degrees of a permissible 460°F (420°F continuous).

This aeroplane is optimised for high speed, high altitude, long distance cruising for two occupants in high comfort, and it does that very well. With such airliner like sophisticated systems, an audio altitude alert warns you that you are approaching your cleared altitude (and again if you inadvertently depart from it). Levelling off gently at 25,000ft (FL 250) and leaving the power at 33. 5 inches and 2500 rpm, we allowed the Acclaim to accelerate to its maximum speed of 155kt IAS or 234kt TAS. This was slightly lower than the manufacturer’s quoted 237kt top speed, since our outside temperature of -24°C was rather higher than ISA and the draggy tie-down rings had been left in place under the wings, but nevertheless more than 50kt faster than the Acclaim’s normally aspirated brethren.

Teledyne Continental recommend using a cruise power of 262hp (194kW), or 82 per cent of takeoff power (but presumably 75 per cent of what this big engine’s really capable of). To calculate this, we read off the recommended power settings from the left sun visor.

they have somewhat less room than the front occupants, and rather restricted forward vision, thanks to the pilots’ headrests. But this is made up for with those long panoramic windows, while a moulded ceiling panel contains overhead vents (fed from a NACA scoop in the fin) and lights plus speakers and oxygen outlets. Outboard, on the sidewall arm rests, each passenger has a small control panel with their headset socket and light switch.

Behind the individual rear seats is a generous 0. 63m3 baggage area with in built securing straps and a reasonable weight limit of 54kg. If you fold the rear seat backs forward like a station wagon’s, the volume increases to 1. 09m3, while the load limit goes up to 154kg. Above and behind this area is a small hat shelf that can carry up to 5kg, although this is sacrificed if air conditioning is fitted.

Further back in the rear fuselage are the batteries and all the avionics boxes.

These can be accessed through large panels on either side of the aeroplane, so that technicians don’t have to crawl around in your lovely cabin or fiddle about beyond the instrument panel. In here are also the autopilot and the brake reservoir, and a little aft are the new, slightly raised static ports. There is also an external power socket on the rear left fuselage side, which Corby pointed out would be very handy for those wishing to become familiar with their new and comprehensive avionics in the safety and privacy of their own hangar.

Starting the TSIO-550 is quick and easy, hot or cold, provided you follow Continental’s procedures, and the engine runs very smoothly at all speeds. Corby said “Continentals just love their fuel”, as he re-started the hot engine later on a warm day for our photo shoot. He left the throttle exactly where it had been on shut down (with the engine idling at 900rpm). A momentary prime was followed by cranking the engine in lean mixture with the fuel pump still running.

It immediately burst into life, so he shot the mixture plunger forwards and kept the occasionally faltering engine going with appropriate bursts of throttle until, after a few brief seconds of hesitancy, it settled into its now familiar steady, thrumming rumble, slightly reminiscent of a Harley Davidson.

Forward vision through the shallow screen was much better than I had anticipated, thanks to a comparatively low coaming and those sloping cowlings, so you can see the tarmac 20m ahead. Here, once again, a bifocal-wearer would be at a disadvantage, although of course all these figures and more are available in the Pilot’s Operating Handbook (POH).

Throttling back a little to 30. 5 inches, but leaving the rpm at 2500, we saw a slight reduction to 154kt IAS (233kt true) on the EFIS, but at a much reduced fuel flow of 22 US gal/hr (82 lit/hr) at the best economy mixture EGT of 50°F leaner than peak.

To give some indication of the practicality of this kind of high speed, long range cruising, this very aeroplane had flown from the USA to Australia in just three days, via Hawaii and Pago Pago, and without ferry tanks.

The only shortcoming of this sort of high altitude operation is the need for oxygen. This demonstrator had lightweight, transparent plastic masks with thin green elastic headbands, like those used in hospitals and on airliners for sick people. Unfortunately mine did not sit well on my head with all the other clutter of those magic Bose ANR headsets, my traditional Ray Ban sunglasses and the boom microphone, which had to be shoved into the bottom of the mask for us to hear one another, inevitably allowing some of the precious oxygen to escape.

And then there is the need for continual checking of one’s mental performance and acuity, plus the intermittent inspection of one’s fingernails to ensure they are not going purple, or worse, blue.

For, make no mistake, 25,000ft without oxygen is not anywhere you would want to be for more than a few seconds.

The recommended emergency descent configuration is with the throttle closed, airbrakes extended and wheels down at 165kt, which should achieve descent rates in excess of 3000ft/min, getting yourself down to safety in less than five minutes.

On the other hand, a serious benefit of such high altitude operation is the Acclaim’s gliding range, which is up to a superb 48nm from 25,000ft at around 90kt. Hit the Garmin’s ‘nearest’ button and you would be unlucky not to find an airport to land at safely within gliding range.

Of course, in this aeroplane you have the option of operating down at 10,000ft and foregoing the oxygen, as we did later. I know which I would rather do.

At this level, you only sacrifice 30kt of true air speed (172kt IAS, 203 TAS) at the slightly reduced fuel consumption of 21. 4 US gal/hr (81 lit/hr), while getting a rather more detailed view of the countryside flowing inexorably past those wide picture windows.

The TSIO-550’s handling is not as critical as are some other turbocharged engine installations, and the cowlings’ excellent cooling ensures engine temperatures always stay reasonable, even on the hottest days – all without resorting to the use of adjustable cowl flaps, which so often become just another thing to forget! Nevertheless, significantly reducing manifold pressure while increasing speed to descend can still cause shock-cooling damage, so it is standard operating procedure to extend the airbrakes for descent.

These airbrakes have no limiting speed, and increase the Acclaim’s descent rate by at least 500ft/min at constant power with no significant trim change, although they do cause a little, barely noticeable buffet at higher speeds. This diminishes as their effect reduces when you slow, and they can be left out throughout the landing to reduce float if you wish (although of course it is always better to come in at the right speed). At Serpentine I popped them out immediately after touchdown to help shorten our landing roll, although below 60kt their effect might be more theoretical than practical, but it could not hurt and might even help to get more weight on to the main wheels to assist with braking.

Allowing the autopilot to fly the Mooney in its descent, Corby showed me that if we let our airspeed increase much above 180kt, the autopilot would pitch up the aeroplane’s nose to keep IAS below the 194 knot VNE. By reducing power slightly to 29in, while leaving the rpm at 2500 and with the airbrakes extended, we achieved a comfortable 600 to 700ft per minute downwards at 170kt, and rather to my surprise, suffered no ear problems, even with my raddled old eustachian tubes.

Descending further to 6000ft, we sampled the Acclaim’s low speed manners.

This revealed no surprises at our forward C of G, the clean stall just about happening at 64kt in lots of wallowing, after proper buffet a mere knot earlier.

Prior to that, an insistent female voice had repeatedly warned us “check gear, check gear,” and then “stall, stall,” from below 68kt.

Maximum landing gear extension speed is 140kt, with an increase to 165 permissible once it is down, although retraction is limited to 106kt. Maximum flap speed is 110kt. Selecting full flap gives a large nose-down trim change, needing nearly full nose-up trim at 70kt.

The stall attitude in this dirty configuration was lower with full (33 degrees) flap and gear down, with no real buffet, but a surprising lightening of the pitch force as our lady friend again started warning us “Stall, stall” at 61kt. This time we got a proper pitch down and a slight left wing drop at 57kt. Maximum height loss (without really trying) was 350ft, but retaining the back pressure did induce a high descent rate in both configurations.

Opening the throttle proved we couldclimb at 500ft/min even with the flaps, landing gear and airbrakes all extended, although there is a strong pitch up with full power. This increases to serious proportions when you retract the flaps, so it is wise to start trimming with your left thumb as you open the throttle, and keep your thumb on that button as you accelerate and reconfigure.

Having burned off enough fuel to be below the Acclaim’s maximum landing weight, we let down into the circuit at Murray Field. I had previously decided to make my first landing on this rather longer, wider 1143m runway prior to squeezing our slightly hot ship into Serpentine’s narrow, 800m Runway 23 for the formation sortie.

The main trick in such a low drag, slippery machine is remembering to slow down in plenty of time. I didn’t, and flew my customary tight (within gliding range) circuit pattern, so my first approach was rushed and unstable, with a sideslip needed to get us down on to the ideal glide slope. Nevertheless, we were eventually settled down at 75kt and approximately on the correct slope by 500ft on final.

We had already agreed that despite it theoretically being possible to make a touch and go landing, because we would have to re-select the flaps to approach, run that slow elevator trim to the takeoff setting and carefully modulate engine power at 33. 5 inches again, it would be much more prudent to make our first landing a full stop. This was never meant to be a STOL aeroplane, so runways of less than 1000m, and in particular unprepared surfaces, need to be approached with appropriate caution.

Corby has his own preferred technique.

This involves flying downwind level clean at 100 to 110kt with 15in of manifold pressure, then dropping the gear abeam the threshold, reducing power to 13in, and selecting approach flaps for a 500ft/min descent to base leg, which is flown at 90kt. A shallow final approach is initially flown at 80kt, reducing to 75 with full flap on short final, and 70 over the numbers to get the minimum landing distance.

The aeroplane arrives with around four degrees nose up pitch, so there is little need for a true flare (and there is not a lot of tail bumper clearance thanks to that lengthened fuselage). Corby does not make a flare with his elevators, but advocates simply closing the throttle and running the tail trim nose up as you cross the fence. I found this technique hard to adapt to, although I could see the advantage of trimming out the fairly high residual elevator forces.

As he said, with those limited propeller and tail bumper clearances, you need to get the touch down attitude correct first time. If you do get it all right, your lady friend calls, “stall” just once before your main wheels squeak on to the bitumen.

Unfortunately, on my first effort I flared a little too high and, finding the elevator load surprisingly heavy, ballooned, but recovered to suffer a little pitching float along the runway as I felt the wheels down on to the ground.

Subsequent landings improved significantly, a Mooney characteristic that many writers have encountered. Fortunately, the wide track main gear helps with any gusts, and the demonstrated maximum crosswind is a usefully high 18kt for both takeoff and landing. As we rolled to a halt having used perhaps 1000m, I was glad we had opted for Murray Field’s longer runway for my initial attempt.

For my second circuit we flew a rather wider pattern. This time I noticed the controls were lighter but less effective at low speeds, and the rudder definitely has to be used to centre the slip ball in turns.

Even with full flap, this airframe is still clean, needing only a trickle of power on final. This time I remembered to start trimming immediately before selecting full flap so that both the required trim and the flap arrived at the same time.

We had already seen that the low-set wing’s significant ground effect could make the aeroplane float prodigiously along the runway if you come over the hedge too fast, but I was told it will also porpoise on the rubber suspension if you force it onto the ground too soon. So, flying and holding an accurate approach speed in the Acclaim is vital.

On my third approach, by now with a better feel for the aeroplane, and using the proper techniques, we easily stopped within Serpentine Runway 23’s 800m on my penultimate landing in the 10kt head wind. The brakes can be very capable if they are really needed, and I thought the Acclaim to be surprisingly easy to fly for so fast an aeroplane, although its rather firm suspension and vulnerable main gear doors really suit it better to long hard bitumen or concrete runways than to smaller, gravel or grass airfields.

Mooney no longer makes any fourcylinder engine aeroplanes, concentrating instead on the upper end of the market.

So a maximum of 125 of these luxurious airframes will be built each year. This means that only a discerning few pilots will be fortunate enough to become owners.

If you collect your new aeroplane from Mooney’s San Antonio, Texas, marketing, sales, delivery and service centre, you can take advantage of its free four and a half day FlightSafety course. This comprises three ground school lessons, two fixedbase simulator rides and flying training in your own brand new aeroplane, including general handling, slow flight, emergencies, instrument approaches and advanced practical engine handling (a very useful addendum when you are going to operate such a sophisticated motor). I am told that two and half days are dedicated to learning the intricacies of the comprehensive Garmin G 1000, which seems about right.

The Acclaim has greater range than any of its competitors, and is faster than any other civilian piston single, although its handling, while still good, is a little less crisp than some of the competition’s, with heavier controls and rather slower responses.

However, for pure speed and range the Acclaim outstrips the lot, and yet is cheaper than all the others, making it the most superb value for money for a long-range point to point machine.

Both confirmed Mooniacs and all other connoisseurs of fast aeroplanes the world over will love it.