Category: Rare Aircraft

Rare Aircraft – Piper’s Fastest

Posted in Rare Aircraft12 Comments

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

Piper PA-24-400 at Airliners.net
Another PA-24-400 at A.net

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

PA-31P-425 at Airliners.net
Another flying at Airliners.net
PA-31P-425 cockpit shot (with rare, old avionics) at Airliners.net

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.

A rare - and still good looking - Pressurised Navajo operated by the Croatian Air Force, coded 014. The only one of it's type in Croatia, it unfortunately rarely - if ever - flies (photo: myself)
A rare - and still good looking - Pressurised Navajo operated by the Croatian Air Force, coded 014. The only one of it's type in Croatia, it unfortunately rarely - if ever - flies (photo: myself)
One could be fooled into thinking this is a Cheyenne with piston engines...
One could easily be fooled into thinking this is a Cheyenne with piston engines... (photo: myself)

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

PA-42-1000 at Airliners.net
Another 400 at Airliners.net
And another from the same source

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

Rare Aircraft – Cessna’s Oddballs

Posted in Rare Aircraft1 Comment

By Boran Pivčić

Every now and then, I get the urge to dig through the Airliners.net database looking for “oddball” aircraft – aircraft that almost made it to life, made it but sank into obscurity, or simply served as platforms for famous aircraft before being forgotten and discarded. My fascination with the above almost always centers on the Big Three – Beechcraft, Cessna and Piper – big corporations that produced some of the most famous aircraft of all time… and naturally had some upsets along the way.

Cessna – with their diverse line of everything from the 150 to the Citation X – naturally caught my attention first and it didn’t take me long to find three candidates that perfectly fit my criteria. As such, these aircraft had to be mass produced at some point in their lives and sold to civilian customers, but be little known and quite rare today. The list could have gone on for awhile, but I chose the 175 Skylark, 205 Super Skylane and the 336 Skymaster.

1. Cessna 175 Skylark:

Years produced: 1958-1962

Cessna 175 at Airliners.net
Cessna 175A at Airliners.net
Another 175A at Airliners.net
Cessna 172B at Airliners.net
Cessna 175C at Airliners.net

The most common of the three aircraft chosen, the 175 was designed to fill the gap bewteen the Cessna 172 – then still in infancy, with just two years of production behind it – and the larger and significantly more powerful 180. As such, it is an evolution of the 172 designed to accept the more powerful Continental GO-300 engine. Rated at 175 HP (versus the 145 HP of early Skyhawks), this engine was a bit of an oddity for a single engined plane, being geared (the G prefix) rather than direct drive as most piston engines are. A common solution on high-power twins of the era, geared engines had a reduction gearbox between the crankshaft and the propeller, allowing the engine to spin at a higher RPM while keeping the prop at lower speeds. Depending on your wishes, this allowed you to either crank the engine up to a higher speed to give more power while keeping the propeller tips below the speed of sound, or reducing prop RPM to make the plane quieter (or a combination of both as in the case of the 175).

Apart from the engine – and the redesigned cowl to accept the gearbox mechanism – the 175 incorporated some minor differences, but pretty much from the exterior looked like any 172 of the era. A little known fact is that the later, higher-powered 172 versions – such as the 195 HP Hawk XP, the 210 HP Reims Rocket, the military T-41 and the retractable 172RG – were evolutions of the 175 design, rather than the basic 172. Fitted with Cessna’s “Omni-Vision” rear windows and direct drive engines, these aircraft were all based on the later-model 175, but marketed as 172s. Indeed, I’ve personally often been in a position to compare the two, flying 9A-DDD, a stock 172N, and 9A-DMJ, an early model FR172F Rocket. DMJ, being based on the 175 which is based on the 172 and 172A, has the narrower and taller undercarriage and tighter cabin, while DDD, produced when the 172 design pretty much froze, has the wider track and lower main gear and more spacious cabin (when I started flying these two, I’ve often wondered why I couldn’t see as much of the main gear from the cabin in DMJ as I could in DDD).

Despite the increased grunt, the 175 was not a major success, with about 2,100 built. The main culpit was the GO-300, which proved to be a bit unreliable – though many now say that it was more the fault of operating technique than the engine itself.  Many pilots without experience on geared engines ran the GO-300 in the lower 2,000 RPM range common on direct drive engines. Designed for the higher 2,000s – around 2,800 as recommended by 175 type clubs – the engine didn’t get all the cooling it needed, leading to frequent breakdowns and relability issues.  A number of sources say that some owners have even switched to larger-displacement direct drive engines, partly due to the added costs of servicing the gearbox (and the fact that parts and rated mechanics for these nowadays very rare engines are increasingly hard to find).

(of note: unlike today, where both the model number and model name are part of the designation, in the 50s and early 60s, Cessnas designated with just the model number were the basic versions, while those with a model name were the deluxe models. So, the “175” was a cheapo model, while the “175 Skylark” was the full-option version. The same was with the first few models of the 172)

Specs for basic, A and B models (Rising Up Aviation): http://www.risingup.com/planespecs/info/airplane279.shtml
Specs for C model (Rising Up Aviation): http://www.risingup.com/planespecs/info/airplane278.shtml

2. Cessna 205 Super Skylane:

Years produced: 1963-1964

Cessna 205 (210-5) at Airliners.net
Another 205 at Airliners.net
Cessna 205A (210-5A) at Airliners.net

While the 175 is not all that obscure, the next aircraft on the list could certainly qualify – despite being the stepping stone to one of Cessna’s most famous piston singles. With a family tree stretching back to the 182 Skylane, the 205 was essentially a 210 Centurion (itself a beefed-up 182) with a fixed undercarriage and an interior optimised for utility, rather than comfort. Evidence to that is it’s official Cessna designation, 210-5, as well as the chin on the front cowl where the nose wheel would have been stowed on the early 210 models – some sources say this was later used to house radio equipment, though one would wonder about the heat from the engine.

That took the form of the six cyl normally aspirated Continental IO-470 from the 210B, rated at 260 HP, driving a constant speed propeller (usually three-blade, but photo evidence shows a number of two-blade models as well). Like the early 210, the 205 did not have the split rear doors that would debut on its follow-up, the famous 206 Super Skywagon/Stationair (early versions of which still had the cowl chin).

The small production run of just under 600 aircraft over two years meant the 205 was offered in just two versions, the basic 205 and the touched up 205A of 1964. Being a converted tourer, it wasn’t all that practical for utility work and was replaced the same year by the more powerful and purposeful 206.

Specs (Rising Up Aviation): http://www.risingup.com/planespecs/info/airplane233.shtml

3. Cessna 336 Skymaster:

Years produced: 1963-1964

Cessna 336 at Airliners.net
Another 336 at Airliners.net
And another at the same site

A Skymaster you say? But they’re not obscure… despite clearly deserving the “oddball” epythet any way you put it :). Indeed, the 337 Super Skymaster is a relatively common sight today, but it’s predecessor, the “normal” 336 Skymaster, is a first class rarity today as it was during its production run.

On the ground, it’s hard to tell them apart at a single glance (despite the 336 being a tad smaller) and only the most astute will notice a most interesting oddity on the 336 – the fixed undercarriage. An unusual configuration for a twin, I must admit I was instantly interested when I learnt of this a couple of years back – despite the Italian Partenavia (former Vulcanair) P.68 light twin sharing the same trait.

Initially, the 336 was designed as a four seater, built around two 175 HP GO-300 engines, the same as on the Skylark. Only the prototype was built in this configuration however, the design being changed to accommodate six, as well as  new 195 HP direct drive IO-360 engines, before deliveries began. Other changes included larger vertical stabilizers, revised wings and some other minor changes to improve handling.

Like the 205, the 336 had a short life and only 195 were produced in a single version before production switched to the bigger, more powerful – and retractable – 337 Super Skymaster (the Super later being dropped).

Specs and performance comparison with 337s (Skymaster.org.uk): http://www.skymaster.org.uk/perform.asp