By Boran Pivčić
Of course, Cessna is not the only one to have a couple of oddballs in its lineup. Piper ranks high up there as well, with a number of significant or interesting aircraft that had the misfortune of being unjustly forgotten. To make things more interesting, Piper also has a tendency to cram a lot of power into some versions of their popular models, creating fascinating hot ships that are today both very rare and highly prized.
The three aircraft I’ve chosen – again after extensive digging through the Airliners.net database these past few years – represent a mix of singles and twins, both piston and turbine, all variations of some of Piper’s most famous aircraft: the Comanche 400, Pressurised Navajo and the monstrous Cheyenne 400 (I had thought of including the PA-60 Aerostar as well, but that plane is a story in itself 🙂 ).
1. Piper PA-24-400 Comanche 400:
Years produced: 1964
Often called the “Queen of the Comanches”, the 400 was Piper’s attempt at making a high-speed single engine tourer. The subtle clean aerodynamics approach of today’s Lancairs was obviously frowned upon, because the 400 – as it’s name says – sports an incredible 400 HP! The power comes from an engine as unique as the aircraft itself, the eight cylinder Lycoming IO-720. That’s 720 cubic inches of capacity, or an impressive 11.8 liters. Those of you with experience in GA may have already seen that a 400 HP IO-720 nicely divides into two 200 HP IO-360s – one of the most popular four cyl engines of modern times – and you’re right: the IO-720 is basically two IO-360s stuck together at the crankshaft :). Ingeniously simple – though there were some problems with cooling the rear cylinders in flight (unlike other 6+ cylinder non-radial engines which are water cooled, the IO-720 remained air cooled).
To control the extra power, the Comanche 400 was fitted with a strengthened rear fuselage and completely new rear control surfaces taken off the Aztec and Twin Comanche. Fuel tanks were also increased to cater for the thirstier engine and thicker wing skins were provided, but otherwise the rest of aircraft is generally identical to the standard Comanches.
However, the Comanche 400 was not without its problems… it wouldn’t be in this post otherwise. A cruise speed of only 185 knots, when leveled against a fuel consumption of 23 gallons per hour at high cruise power, isn’t all that impressive, which made the aircraft quite expensive to operate even back in its day (though it was the fastest normally aspirated single back then). The aforementioned modern Lancairs have significantly higher cruise speeds (by up to 30-40 knots) with 20-25% less power – and fixed landing gear to boot – which makes them far simpler and cheaper to fly and maintain. But on subjective terms, a 60s tourer with four Cessna 150s under the hood still keeps its charm, and the survivors of the 148 built are in high demand today.
Specs (Plane & Pilot Magazine): http://www.planeandpilotmag.com/aircraft/specifications/piper/1964-piper-comanche-400.html
2. Piper PA-31P-425 Pressurized Navajo:
Years produced: 1970-1984
Another interesting (to me fascinating) and rare aircraft to come from the Piper works is the PA-31P-425, a unique Navajo modification that is the only Piper pressurised piston twin. You’ve probably noticed by now it’s striking resemblance to the turboprop Cheyenne I and II – though they’re not directly related. Same problems warrant same solutions, hence two aircraft that look almost the same. In reality, they were developed almost concurrently from the basic PA-31-350, sharing components to add a pressurisation system, the needed fuselage changes and various structural and landing gear updates to handle the increased weight.
As the pressurisation system saps quite a lot of engine power, the haul itself at a respectable speed the Pressurised Navajo was equipped with massive TGIO-541-E1A engines – turbocharged, geared and fuel injected – producing 425 HP. With all of this power – 850 HP in total – you’d believe the P-Navajo could touch Mach 1, but as mentioned, most of the excess power was spent on spinning the massive turbocharger, which needed to be large enough to both charge the engine and pressurise the cabin with bleed air. But, like the Beech 60 Duke that had a similar system, this led to a highly complex engine (the Duke – which was labelled as very maintenance intensive – didn’t even have geared engines), which consequently kicked the operating price up.
All of this – combined with a production run of only 259 aircraft – make the P-Navajo a prized aircraft with a unique character, pretty much the case as with the Comanche 400. Sadly, if the Airliners.net database is anything to go by, few appear to be flying nowadays.
Specs (Airliners.net): http://www.airliners.net/aircraft-data/stats.main?id=311
3. Piper PA-42-1000 Cheyenne 400:
Years produced: 1984-1993
What better way to finish this post than with the awesome Cheyenne 400 – in a nutshell, the biggest, fastest and most powerful aircraft that Piper has ever built. A modification of the standard PT6-powered PA-42-720 Cheyenne III, the 400 sports two 1,000 HP Garrett TPE331 turboprops, driving imposing four-blade composite propellers, which together give it a cruise speed of an impressive 335 knots – almost 60 knots faster than the equivalently-sized (and far more expensive) Beech King Air 200. At maximum cruise, the 400 can outrun even the Big Brother King Air, the 350, by a comfortable 20 knots.
With almost 30% more power – but only 6% more weight and the same dimensions – than the Cheyenne III, the 400 (originally designated the Cheyenne IV and 400LS) was designed to compete with smaller bizjets such as the Cessna Citation I and II. In the event, only 43 were ever made, making it one of the rarest and unique production aircraft in the world today.
Specs (Rising Up Aviation): http://www.risingup.com/planespecs/info/airplane363.shtml