Pilot report - Piper Comanche
[Reprinted from Fliteguide / Imperial Aviation]
Piper was never quite the same after the Susquehanna River
burst its banks and flooded their Lock Haven factory back in June 1972. It wasn't
the first time either, but the 1972 floods caused huge damage and it was the
last straw for Piper. The flood destroyed 100 new aeroplanes and irreparably
damaged many of the company's manufacturing jigs including those used to make
the nearly 8000 Comanches.
Some aergue that the 1972 flood came at a fortuitous moment as it pushed Piper
into replacing the Comanche with the Arrow which cost a lot less to produce.
Indeed, when the Comanche prototype first flew in 1956 the company was going
through a minor engineering revolution (at least for Piper). They were beginning
to rdge out tube and fabric construction for monocoque. The twin engined Apache
of 1954 was the first effort at getting away from fabric fuselages though the
aircraft retained its tubular steel airframe.
It took over eleven years for Piper to catch up with Beech who'd launched their
V-tail Bonanza in 1947. By the time the first 180hp and 250hp Comanche's came
off the line in 1958, the Bonanza was already the clear market leader and had
a decade's worth of monocoque manufacturing experience tucked under its belt.
Cessna were not far behind and they had test flown their first retractable 182
in 1957 later to become the 210. The Comanche was an expensive aeroplane to
produce. A 250hp version cost US$24,500 in 1958 - US$2,000 more than a 1960
Cessna 210 and US$300 more than a J-35 Bonanza. Nevertheless, Piper made five
variations of the Comanche line from the 135 knot 180hp model to the awesome
1964 400hp. In between, the company installed the 250hp engine and a normally
aspirated and turbocharged 260.
Comanche's were liked by their owners for their respectable cruise speeds, big
cabins, useful range, kind handling and trouble-free Lycoming engines. The 260
model was introduced in 1965. The '65 model was identical to the 250 except
in engine power and some Piper buffs consider it the best of the line. The 260
was the inly four-seat carburetted Comanche and thus had an astonishing climb
rate of 1600 feet per minute from sea level. In 1966 Piper stretched the fuselage
slightly and added two more seats. In practice, the extra accommodation was
nothing more than a couple of padded cushions placed in the back with legroom
that allowed for nothing more than small children. The seats were placed in
the luggage area, so if all six places were filled, no room remained for baggage.
Piper also added an extra window each side. The '66 'B' model had its payload
increased by 200 lbs to give a max up all weight of 3,100 lbs. The speed advantage
over the w250 model was negligible and at the same weight the 260 model could
manage an extra four knots.
In 1969 Piper launched the 'C' model - instantly recognized
by its shark nose. The company had to extend the propellor forward to counter
an aft C of G problem after raising the useful load to a handy 1,427 lbs. The
last of the line was the turbocharged 260C which was considered the best of
the lot - better even than the 400hp hotted-up Comanche that wowed Piper fans
in 1964. The 260C turbo was often referred to as being 'turbo-normalised', a
cute description which tried to explain the unusual installation of dual Rayjay
turbochargers which came on line with the application of a separate 'throttle'
mounted on the power quadrant. To operate the turbos pilots would have the extra
throttle closed on takeoff and only opening it during the climb to maintain
manifold pressure. The lever controlled the wastegates, closing them and at
the same time directing more exhaust flow into the turbocharger. It wasn't an
altogether happy arrangement as the process led to some power loss due to the
inefficient induction system when not using the turbos. The turbochargers made
a significant difference when flying over 12,000 feet. They had the added benefit
of quietening the cabin although Lycoming had to beef up the engine to withstand
the higher operating temperatures.
Comanches have always been good looking aeroplanes. One of
the reasons production costs were so high is because of the pretty, tapered
semi-laminar flow wing. Achieving a super-smooth surface in the fifties with
traditional riveting methods was not easy and had to be carried out with supreme
care. Comanche's thus rewarded their owners with pleasant stalling manners.
The aircraft sits low on its undercarriage - a configuration that's led to much
heated debate over its landing qualities. The Comanche has acquired a reputation
for being difficult to pull of greasers. Indeed, those unfamiliar with the type
will be frustrated by its tendency to float and then suddenly plop onto the
runway with a bone-jarring thump. Every Comanche owner will have explored the
landing qualities and come up with his or her favourite method. A universally
accepted way of improving the landing (and takeoff) behavior is to pump up the
main gear oleos and even bleed off the nose wheel strut slightly. This further
reduces the Comanche's tendency to wheelbarrow during takeoff by placing the
aircraft in more of a flying attitude during the ground run.
Comanche's have always been praised for their roomy cabins.
There's a single door on the right hand side of the fuselage which curves some
way into the roof area to make getting in and out fairly easy. Second row passengers
will enjoy the wide comfy seat with good legroom. Those right at the rear will
have to suffer placing their knees close to their chests unless it's fairly
young children occupying the last row. The rear area has a weight limit of 250
lbs which should in theory accommodate at least one adult and some luggage.
A baggage door on the left hand side of the cabin behind the wing trailing edge
means that while items can be stowed from the outside, occupants will have to
clamber over the first row of seats.
The panel is classic sixties - roomy and wide. The primary flight instruments
are placed in a typical 'T' layout with a centre stack of avionics and engine
gauges to the right of the panel sharing space with the fuel and temperature
indicators. Switches are placed along the lower left area and the fuses on the
opposite side. The power quadrant is where it should be - in the middle. The
Rayjay turbocharger extra throttle lies to the left of the primary throttle
and has a specially designed 'stop' to prevent it being advanced further than
the power lever. Suction and EGT instruments are placed below the flight instruments
and the cowl flap lever is underneath the panel to the left of the centre pedestal.
The undercarriage switch and flap control are either side of the quadrant.
Just as the Comanche has idiosyncratic ground handling, Lycoming engines have
frustrated pilots with their fiddly start performance. Like all fuel injected
Lycomings, the IO-540 is best started in the 'idle-cutoff' position. With the
boost pump showing positive pressure via the flowmeter
with the throttle opened a quarter of an inch and the mixture at full rich,
the mixture is then fully retarded and only pushed back in again as the engine
fires. Once started the engine idles with a lumpy resonance so typical of the
bigger Lycomings although as it warms up things get a little smoother which
is a fair indication that the engine is ready for power checks. The Comanche
has a short wheelbase which can be felt with a hard 'pitchy' ride when taxiing.
At the holding point the engine is run up to 1500 rpm and the propellor cycled
before increasing to 2200 rpm for the magneto and temps and pressure checks.
With the fuel pump flicked to the on position and lined up on the runway the
view over the nose is slightly restricted by the aeroplane's tail-low attitude
and lengthy cowl.
Recognising the Comanche's ability to wheelbarrow, the handbook
recommends a light back pressure on the control column during takeoff. Furthermore,
at altitude, the book recommends the manifold pressure be set at 28.8 inches
on takeoff, allowing for a maximum of 29 inches with the ram-air effect using
the second throttle that controls the two Rayjays. The 260C has a maximum takeoff
weight of 3200 lbs which with the tanks full to 60 gallons allows just under
an impressive 1000 lbs of payload - or five adults and 96 lbs of baggage. The
book claims a takeoff run of 2600 feet (795 metres) at gross with a further
700 feet to clear a 50 foot obstacle at a density altitude of 6000 feet on a
30 degree Celsius day.
For the flight test we were two up with about half tanks which weighed in at
nearly 2414 lbs. At this weight the Comanche leapt
off Wonderboom's main runway. Although these aircraft have a respectable field
performance, like most other aircraft at gross weight they need a good distance
to get airborne with Africa's hot and high conditions.
The aircraft is rotated at just over 60 knots and flies itself
off shortly after. Best rate of climb speed is 97 knots. At gross weight a healthy
climb rate in excess of 1000 feet per minute can be expected at a density altitude
of 6000 feet. Maximum angle climb speed is 87 knots. The owner of the test aircraft,
Doctor Jannie Tromp, has had an inflatable door seal fitted and whilst the Turbo
260C is the quietest of the Comanche series, the sound level was even lower,
enabling normal conversation tones in the cruise.
At 7500 feet we set up the aeroplane for cruise, recording 140 knots at a 65%
power setting, 23 inches of manifold pressure and 2300 rpm burning 12 gallons
of fuel per hour. At this height, admittedly lower than many pilots of turbocharged
aircraft will opt for, a manifold pressure of 27 inches, 2400 rpm brought the
speed up to 161 knots for 15 gallons per hour. This Comanche is fitted with
oxygen and on a long trip, pushing the aircraft to 20,000 feet will increase
speed to nearly 200 knots. The aeroplane is certified to fly up to 25,000 feet
so pilots wanting to take advantage of high altitude winds can do so bearing
in mind that the difference between high cruise and economy cruise (65% power)
is about 100 miles.
Those appreciating a fine handling aeroplane won't be disappointed with the
Comanche. Although Piper handling arguably deteriorated over the years, the
Comanche line all had light, crisp ailerons and pleasantly harmonized controls.
The C models were a little heavier than earlier examples
due to an aileron-rudder interconnect. The trim wheel is mounted on the roof
which isn't the best arrangement but followed typical Piper practice until the
appearance of the later Warrior and Arrow models.
At the stall the Comanche behaves impeccably. Piper
installed a visual warning system which alerted the pilot of an impending stall
by a red light mounted prominently on the panel above the airspeed indicator.
Again, this shows little imagination and whilst owners will rarely fly this
aircraft to the point of stall, an aural system is far better and has been universally
adopted by other aircraft manufacturers (including Piper nowadays). The stall
break comes at 65 knots clean with the red light beginning to wink at 73 knots.
With flap and gear down, the break is at 58 knots. There's virtually no tendency
to drop a wing but considerable airframe buffet goes some way to make up for
the lack of an aural stall warning system.
Returning to the field, the Comanche needs to be slowed to
130 knots before lowering the wheels and 110 knots for flaps, The gear is electrically
operated via a cable that drives a worm gear. The system has proved remarkably
reliable. However, in the event of a gear failure, speed has to be brought back
to under 90 knots and the motor disengaged from the drive, whereupon the wheels
drop free and lock down. It is impossible to raise the wheels once the emergency
system has been activated and the aircraft has to be jacked up to restore the
system to fully operational status again.
The Comanche pitches nose down as the gear is lowered - easily countered by
a small turn of the trim handle. Furthermore, there's a noticeable braking effect.
Flap extension provokes even less trim change. Approach speed at gross weight
and no flap is 92 knots, 85 with 15 degrees of flap and just under 80 with full
flap. 85 knots and full flap is perhaps a happy combination and with a gentle
flare the aircraft sits down nicely with little tendency
to float.
Many lament the passing of the Piper Comanche and today the type remains a sought-after
aircraft. The example tested here - V5-JRT is based in Windhoek and is in pristine
condition. The Comanche produces few maintenance surprises but has had its fair
share of Ads. The most serious is the requirement to inspect the main wing spar
for cracks. The AD was issued following a wing separation tragedy after a pilot
had pulled up doing a beat up over a friend's house in Canada. The AD called
for the provision of a wing inspection panel so that the spar can be inspected
every 100 hours. According to the FAA, no cracks have subsequently been found
and it appears the AD has since been changed to a mandatory service bulletin.
The inflatable door seal was introduced as an optional mod to prevent poor door
sealing. Owners could also install an extra latch in the roof to alleviate this
age-old Comanche problem.
[END OF REPORT]
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