Airtest – Piper Arrow IV

Although the IV is basically an Arrow 111 with a T-tail, the new design for ’79 is an exercise in further perfecting a near perfect type – something none of the Big Three have found easy as the years progress.

The first obvious thing for Lock Haven to do was to substitute a T-tail for the older conventional empennage. This has done the expected:

• It has ironed out pitch changes, noise levels in the drumming department and enhanced handling characteristics in a type already unrenowned for vices.

• True, one has to make a conscious effort not to apply significant back stick on the take-off run until late into the roll, or get popped off the ground in a nose-high attitude like a mini-Harrier.

One of the more noticeable mods. fitted to the Arrow IV during an external inspection is the stabilator’s inverted slots – an interesting device designed to help pitch control at low speeds.

Basically, what happens is that as the stabilator runs out of airflow at the lower end of the speed scale, air starts travelling through the inverted slots, helped by a pair of end plates.

Be that as it may, the Arrow IV has a heavy elevator as it nears the stall – which may of course be all to the good in acting as a gravity-powered stick-pusher.

Many of the “new items” in the ’79 Arrow IV lie within the excellently-finished fuselage and wings. The now-familiar “Warrior Wing” can carry up to 72 galls/US usable – which in one way accounts for the Four’s long legs. And that wing, with NACA figures of 652-415, looks set to stay for some years until and- unless someone finds a section with better performance and faithfulness.

Three leading edge burble strips each side help that true response to any pilot’s stall input – the break isn’t there, however hard one hauls on the pole.

Inside the semi-monocoque fuselage, a world of soft velour, contoured seats and front-seat hydraulic adjustments awaits the driver. It’s obvious that Piper has racked their brains to see what else these ivory-from-the-neck-up pilots can get up to in the world of trying to make an aircraft do what it shouldn’t; one little mod involves a pop-up tab over the Mixture slot.

Hands up to those who haven’t been guilty of trying to reduce revs and finished up with the Mixture at Idle CutOff . . .

Piper’s do-it-yourself undercarriage lowering system is standard on the Four, and they’ve stuck with the time-honoured long-handled wing flap lever (manually operated, giving 0, 10, 25 and 40-degree settings).

Another mod getting 10 out of 10 for simplicity, practicality and downright obviousness is the engraving on the left-hand sun visor. Prop and power settings are etched in clear lettering on the visor, making fishing for the Manual or that little scrap of paper a thing of the past – until you break the visor off.

Our evaluation was made with demonstrator VH-FTT as the subject, made available by Ansett General Aviation at Bankstown with Keith Robey as an obliging: shotgun. The copy (oh, the temptation to announce oneself as “Arrow Four Ft. . . ” in the circuit) boasted just about everything on the panel, including an auto-pilot and many avionics.

Walkaround clinched the claim that Piper’s external finish is up to its usual second-to-none standard, and the fact that all the relevant items in the T-tail configuration can be in spected without a wooden box, step ladder or by sitting on a passenger’s shoulders.

If we had snow in Australia, getting the stuff off the top surfaces could present a problem in unorthodox calisthenics.

In the office, a black-backed instrument housing makes the dials and gauges stand out like organ stops. Visibility is excellent, comfort ditto.

The one-door entry is something to be negotiated with caution for ageing drivers and passengers, but once inside the atmosphere and actual space is something eminently satisfying.

Visibility, legroom, air and actual seating got high marks in our checklist. Cabin ram air is provided via a gauze-covered slot in the vertical stabiliser’s leading edge, near the root – another preflight stopping place to inspect for bugs, etc.

As mentioned, FTT was a demonstration model with six of everything; but even so, the panel appeared relatively clean. Flight instruments immediately in front of the left-hand seat, temperature and pressure dials below, auto-pilot under that lot, rpm and manifold pressure dials to the right.

The centre section was taken up with lavish nav/com equipment, with Master and other switches below. The bottom right section housed circuit breakers, the exhaust gas temperature (EGT) gauge and air-conditioning.

Power, prop and mixture controls sit in quadrant fashion, just to the right of the undercard knob. Fuel selection and management are manipulated from a dial set about calf-high on the pilot’s left side.

Piper’s patent fail/safe undercarriage lowering system sits between the two front seats, with rudder and elevator trims not far away.

Pre-start drill in this $66,500 demonstrator includes cracking the power lever fractionally open, master switch ON, auxiliary fuel pump ON, mixture to prime then Idle Cut-Off after a fuel flow indication registers.

Warmup after the -IO-360-C1C6 Lycoming fires and settles down, is usually at 14-1500rpm. The powerplant is rated at 200hp/2700rpm, and drives either a McCauley or Hartzell twin-blade prop.

Our evaluation sortie was conducted at about 50016 under gross and with two p. o. b. plus near-full tanks. The wind was fickle, and the outside air temperature (OAT) near +28C as we neared the holding point and noted the secure-feeling ground ride and manoeuvrability.

Take-off technique, in view of the “pop-up” tendency, explained earlier meant letting the beast run until about 65Piper in recent years have certainly promoted the T-tail design. They claim that with a T tail, the rudder has an undisturbed airflow over it even when the aircraft is close to or in a stall or spin. Piper claim that a low tailplane tends to blanket the rudder, making it less effective. knots indicated, then gently but firmly milking the stick back to avoid an excessive nose-up attitude.

Acceleration was brisk and steady, with elevator trim just aft of neutral and a sniff of right rudder trimmed in to counteract torque. Positive back-pressure was applied as the airspeed indicator wound enthusiastically past 65, and lift-off was achieved around the 72 mark when back-pressure was relaxed and wheels up selected.

A book figure of 1025ft is listed for take-off run in International Standard Atmosphere (ISA) conditions; however, with a lighter load the test aircraft leapt into the upper atmosphere in far less footage and achieved an initial rate of climb (roe) far in excess of the carded 831fpm.

Visibility was bad enough for Bankstown to advise aircraft to stay in the circuit, but we switched on the ADF and other aids and bored on out to the foothills on a runway-heading departure, climbing steadily and adjusting settings to cruise climb – the classic 25/2500.

This Arrow IV is a quiet aircraft, immediately comfortable and exhibiting instant tractability. Visibility is excellent despite a moderately high coaming – and in the indifferent visibility during our evaluation we were glad it was so.

We set up 25. 2/2450 at the top of -our mini-climb to 4000ft, noted OAT sitting at +22 and recorded 145 IAS. Trimming for level flight produced an almost nose-down attitude, and the Four just wanted to keep climbing. This enabled us to get the thing well and truly bedded down on the step.

With 145 showing consistently, we applied corrections and found we were trueing out at a better-than-book 159 knots – about 183 miles an hour.

Coming down to lowspeed ends of the scale after proving that all controls harmonised delightfully, and gliding resulted in an extremely flat angle with a moderate sink rate if 70-75 knots was set up, we experimented with the fail/safe capabilities of the Piper undercard safety system. It worked.

The sensor picked us up at 95 knots after we’d closed the throttle and sent the wheels down with a reproving thump. And the horn kept on blowing until the undercart lever was selected DOWN.

Piper have proved that if undercart UP is selected on takeoff or at any stage whilst groundborne, the gear stays down until 75 knots has been achieved. We didn’t try that one.

Stalls are an essential – if distasteful – part of any evaluation or getting-to-know-you flight with a strange aircraft. Our last Arrow evaluation was some years distant (backwards) in an ex-school hack. It was not an impressive first acquaintance.

Arrow IV cabin was roomy for four adults and relatively quiet for a light single. At around $66,000 (early 1980 delivery) the Arrow represents good value in what is now a competitive class – that of the four place retractable single, which now includes head on competition from Cessna’s Cutlass. About this time we began recalling wing area (170sq ft) and wing loadings (16. 2I6/sq ft) borne by the Four’s tapered wingplan.

And so to stalls – only they weren’t so much stalls as a series of arm-wrenching back pulls trying to get the Arrow IV to drop a wing, a nose – anything . . . while the horn sounded off.

The manual warns that the stall onset is marked by a mild airframe buffet and gentle pitching. We got a whiff of the former and a hint of the latter. But the whole while the stick was fighting us to go back forward again, the Arrow was complaining bitterly about the entire undignified procedure long past the book figures of 60 knots indicated clean, and 55 knots fully dirtied-up, – and we got tired.

Around the 53 knots mark, there was a hint of nose-drop, but the wretched thing bobbed up again even as we were uttering shrill cries of exhausted triumph. It’s easy to crank up to near-Never Exceed Speed (Vne) during a powered letdown, and we noted an IAS approaching the Vne of 190 on our way home to Bankstown.

But it was pure joss slowing down to circuit speed. Undercarriage extension limiting speed (Vie) is listed as 130 IAS (with 109 for retraction limit due, we believe, to door structure limitations rather than the Four’s robust undercart), and gear can be dropped with satisfying drag results without pitching out of one’s mind.

Flap extension speed (Vfe) of 108 indicated adds to the braking effect when needed.

We shot a touch-and-go on 11 Left on our return to Bankstown, to see just how docile this high-tailing hustler really is. Joining non-existent traffic downwind at 90 indicated after dropping the gear (no pitch change here), we crosswinded at 80 while lowering the first stage of flap (again no pitch change) and made a shallow approach on finals while dropping the rest of the flap progressively and eroding speed back until we had just over 60 showing over the fence.

Airspeed was just twitching around the 58 mark – two knots above booked dirty stall speed – as we vaulted the piano keys, and the touch came just as FTT’s stall warning began intoning a steady note.

• There was negligible float through ground effect, and a firm contact. All the way down it was like the man said – there’s no abrupt pitch change when exposing the undercard or flap to the breeze, just a feeling as though the Four pauses for a moment, realises it has something dangling in the slipstream, then resumes its descent trying to recapture its trim speed.

Keith flew a short-field (on our request) and captured much the same numbers -100 IAS downwind, undercarriage down, setting 24/2400. Fuel pump ON, two stages of flap (25 degrees) down before turning into finals at 75 indicated. The OAT registered +28 at this time.

On finals, full flap, speed slowing through to 70 on short finals with 60 over the edge. The same firm touch, and the ability to turn off at the first intersection if he’d wanted to. And Pipers say their Four isn’t really a short-field type . . .

Little wonder the Four is proving to be a hard act to follow throughout the flying world today. Australians in the market have already realised that the little Arrow IV is ideal for private use, with special emphasis added for charter or school work.

If the Department of Transport initiates any further heartstoppers (following its actual threatening to do something in the aviation world after Peter Nixon’s departure) in the light of activating its thoughts on making it mandatory for schools to house a retractable single, it’s a safe bet the Four will be there to help Comm licence training along.

The little Arrow has a few characteristics that purists could enlarge upon; some pilots claim the T-tail wags a little in turbulence (and what light aircraft doesn’t?); others say the Arrow wanders vertically after being trimmed out in cruise – but the phugoids are always convergent resulting in a return to the assigned height.

We recommend the Arrow IV with the same enthusiasm as that shown when we tested the much-lamented Rockwell 114. It’s an aircraft for all seasons and reasons, backed by a thoroughly professional system throughout Australasia.