Single Scoop: The Popularity of the Single-Engine
While I got stuck in to writing this feature, it was serendipitous that the television in the background launched into a documentary on the Wright Brothers, trailing the afternoon news. My aviation-senses tingling, I took a quick recess to go check it out. It was good, investigating the Wright Brother’s journey to Kitty Hawk – and my recess suddenly stretched a tad longer into the afternoon.
Naturally, it got me thinking about how far we’ve come in such little time – it’s hard not to wonder at the dizzying pace that sprouted from that fateful day in 1903. But it also got me thinking about the little guys, the single engine workhorses that have weathered the highs and lows of aviation history since day one.
In some sense, it’s the stoic singles that do the heavy lifting for the industry. Whether it’s carrying us into to battle in wartime or faithfully delivering us from point to point in peaceful skies, the piston single, and later the turboprop single, are at the business end of the aviation spectrum, remaining a perennial best seller all this time. This article is dedicated to the single-engine aircraft.
Piston singles began with the Wright Flyer, despite its dual propellers. Although there were other designers in the United States and Europe who were attempting to fly with one engine paired with a single propeller, the Wright Flyer was low on power and even lower in propeller thrust, so the Wright brothers settled on a twin-propeller, single engine design. Shortly after the Wright’s first powered flight, Louis Bleriot, who had been building single-engine prototype airplanes in parallel with the Wrights’ efforts, created the Bleriot XI, built in 1908 which carried him from one side of the English Channel to the other.
A couple of years later, Glenn Curtiss, who was redound for his daredevil exploits on motorcycles, decided to launch himself into the lofty realms of flight. Inspired by his predecessors, Curtiss’ prowess in gasoline engine design and his eagerness to refine powered flight led to his recruitment in the American Experimental Association (AEA) in 1908. Other members of the Association included Alexander Graham Bell and John Alexander Douglas McCurdy, who became the first British subject to fly an aircraft in the British Empire. Frederick Walker Baldwin, a hydrofoil and aviation pioneer was also a founding member of the society.
Between 1908 and 1910, the AEA produced four aircraft, each improving incrementally over its predecessor. Curtiss primarily focused on the design of the AEA’s third aircraft, the famous June Bug, and like a true daredevil, piloted the aircraft for most of its test flights. On July 4, 1908, Curtiss flew 1,550 m to win the Scientific American Trophy and its $2,500 prize. This was considered to be the first pre-announced public flight of a heavier-than-air flying machine in America.
The Wright Aeronautical Corporation, a successor to the original Wright Company, ultimately merged with the Curtiss Aeroplane and Motor Company on July 5, 1929, forming the Curtiss-Wright company. When Curtiss died in 1930, the company he founded continued, producing some of the more innovative high-speed metal monoplanes throughout the 1930s and 1940s. And on 1 August 1914 when the German Empire declared war, it was quickly apparent that aviation would play a major part in the conflict.
All fighters in the war were single-engined, with notable participants like the Fokker D7, which quickly garnered a reputation as the best airplane of the war. The Fokker D3, also known as the Triplane and the Sopwith Camel tied for second place. All three were particularly notable for their manoeuvrability, speed and kill ratios.
Several basic types of piston engines powered the typically fabric-covered biplanes in the early days of the post-war era. In-line engines, with cylinders either aligned in tandem or positioned in a V-type configuration, required a radiator and the circulation of a liquid coolant. Radial engines, with cylinders arranged in a circle around the crankshaft, had numerous small fins on the cylinder that radiated heat to the passing airstream to keep the engine cool. These relatively straightforward piston-engine designs opened up the possibility of long-range flights and ushered in a new era of passenger travel.
By 1924, the US Army had completed plans to undertake the first aerial circumnavigation of the world, sending four single-engine Douglas “World Cruisers” West towards Asia. Piloting flying a single-engine Ryan monoplane, Charles Lindbergh, made his nonstop solo flight in 33 hours 30 minutes from New York to Paris in 1927. His flight demonstrated the essential reliability of improved radial engines.
The 1930’s heralded in one of the most popular private aircraft models in history – the peppy little Piper Cub, a two-seater powered by a 65-horsepower engine that enabled a cruising speed of about 140 km/h. But it wasn’t alone in the rugged single-engine market. The four-seat Cessna Airmaster, powered by a 145-165-horsepower engine enabled a cruise speed of about 260 km/h. Also on the scene was the seven to nine seat Beechcraft Model 18, powered by two 450-horsepower engines that enabled a cruising speed of about 350 km/h. The Cessna and Beechcraft still used radial-piston engines, but Piper relied on a horizontally opposed four-cylinder engine that allowed engineers to design a more streamlined engine nacelle. This type of engine became the preferred style for modern light single-engine designs.
Piper, Cessna and Beechcraft carried the market through the late 1940s and 50s. The trio marketed high-wing monoplanes with two to four seats, enabling short-range flights for the busy, career minded fellow. In 1947 Beechcraft introduced the Bonanza, a stylish all-metal V-tailed machine, with retractable landing gear, higher speed and a roomy four-place cabin in 1947. Various incarnations of the Bonanza remain in production to the present day.
Through the 1960s, piston-engine airliners still played a key role in air travel. In 1969, commercial airliners accounted for about 2,500 transports, with estimates of 122,500 aircraft operating in the general aviation fleet. Mainstays like Cessna’s 172 Skyhawk and 182 Skylane are enduring names that have carved their own chunk out of the aviation history. First flown in 1955, more 172s have been produced than any other aircraft in the world. Measured by its longevity and popularity, the Cessna 172 is the most successful aircraft in history. A 172 was even used in 1958 to set the world record for flight endurance. The record remains standing to this day. The 182 is the second most popular Cessna model behind the 172 which saw a recent revamp in Cessna’s new JT-A model, a diesel-powered alternative for the Turbo Skyhawk, designed to meet the growing demands of environmental regulations across the globe.
Of course, Myriads of piston-powered light planes continue to populate the airways today, but it’s also likely that a new student pilot stepping out onto the tarmac will be greeted with a fresh, purpose built trainer over an older model, depending on the flight school. Based out of Queensland, Jabiru is an Australian manufacture parked comfortably next to the Bundaberg airport. The J170 was developed for flying schools in hotter climates, with longer wings to allow it to climb faster in hot conditions. Sue Woods of Jabiru says that the range of Jabiru aircraft, from trainers to private aircraft, operate under the simple maxim of simplicity and economics. “The J170 is more popular for the flying school market because of the robust and durable airframe [paired with the] economical fuel consumption of the 2200cc, 80 hp engine” she explains “and the 100 kt cruise speed is more manageable for students”.
For the private owner, Sue Woods describes the J230 as the best fit. “Our J230 is the most popular model for the private owner because of the 3300cc, 120 hp engine giving 120kt cruise speed. More power always is an attraction and” she continues “…the slender lines are also pleasing to the eye”. I don’t think anyone disagrees on that one.
But as Gerard Kitt of Tecnam Australia advises, you’ll need to have a clear idea of what you’re after before heading into the single-engine realm. While pilots will always have a soft spot for their first, there are many variables that dictate the perfect fit.
“One of the advantages of a piston aircraft is the operation costs” he explains. “Low fuel burn, low maintenance and low overhaul if you want to zero time the engine. All around there’s clear advantages in the operations of piston engines over turboprops too,” Mr Kitt explains. While other twins and turboprops may pack a punch… they cost a whole lot to run and they cost a lot of money to maintain”.
Generally, most twin piston aircraft do perform better in terms of load capacity than most singles. But one of the most significant attributes that set the single apart from the rest is, as Sue Woods’ emphasised, simplicity. One engine means fewer controls, a simpler fuel system, a simpler vacuum system, a simpler electrical system and so on. With only one engine to feed, you’ll spend less on fuel as well as oil per flight. And with only one engine to maintain, you’ll only shell out on one set of spark plugs, one set of cylinders and one engine to overhaul when the time comes.
Although modern single-engine airplanes can be equipped with redundancy systems, twins have more to work with than singles – in capable hands, twin-engine aircraft are safer because they provide at least the potential of continued flight in many situations in the event of single-engine failure. Mainly because of their size and weight-carrying capability, many twins have more equipment than singles too, including radar and ice protection devices.
However, in a single-engine airplane, if the engine quits, the airplane tends to remain wings level and yaw straight. If an engine quits in a twin, the aircraft will immediately and dramatically begin to diverge from controlled flight in all three axes. It takes rapid, correct and decisive action to prevent losing control of the aircraft. The slower the airplane is at the time of failure, the more aggressive the pilot needs to be. Under some circumstances it will become completely uncontrollable well before the wing stalls, because of limited airflow over control surfaces to offset asymmetrical thrust. A single will tend to keep flying straight ahead as long as the pilot does not resist the airplane’s natural nose-down tendency following power loss.
With these simplified and forgiving attributes, it’s no wonder that piston singles are the first step in a student pilots’ training. Mr Kitt emphasises the importance of an unpretentious, reliable aircraft to get students going at the controls. “Simplicity is a major factor in determining a single trainer… for a training organisation it’s a really obvious choice to have something that students will take to quickly”. Tecnam’s designers focus on stripping the trainer back to the bare bones with shrewd manufacturing, avionics and power. “[Tecnam aircraft] make ideal trainers [due to] their simplicity and forgiving handling qualities”. Our aircraft are…phenomenal in a training environment because they make the learning process complementary to the aircraft”. ‘[A good trainer should be] easy to fly, which reduces the learning curve significantly. [Trainers] aren’t complicated aircraft [with] unforgiving handling qualities”.
But it isn’t just flying that students need to become competent with quickly. Landing safely back on solid earth is another consideration. “Probably the most important part of the learning process is to be able to land too” says Mr Kitt. “Flying a Sierra or even the high wing E30 or P2000, you’ll find that they are light and versatile aircraft to land…but they suit an experienced pilot too, who just wants a nice easy aircraft to fly…”.
The popularity of a particular aircraft available within a fleet such as Tecnam’s can vary in terms of location too. Technam’s aircraft reside predominantly on the east coast of Australia, where an ideal aircraft can be dictated by numerous variables. “Depending on whether you are north or south really has a substantial impact on the popularity of an aircraft…” explains Mr Kitt. “In the southern states, it’s the low wing Sierra aircraft that buyers prefer, whereas in the north, the high wing configuration is in much more demand due to the climate, weather and intensity of the sun”. Overall, Mr Kitt stated that it’s Tecnam’s low wing Sierra P2002 and the high wing P2008 that customers are after. But the priority overall is matching the plane to the pilot. As Mr Kitt says “you’ve got to find an aircraft to suit your needs. You’ve got to ascertain what the mission of the aircraft is before making any final decisions”.
LSA certification has also made a significant impact on the affordability of single piston industry in Australia. As Mr Kitt explains, the choice is pretty clear cut “the acquisition of an LSA is a hell of a lot less than buying a brand-new Cessna or Piper aircraft out of the factory from Europe. Now you can acquire an LSA with all this modern technology and have a brand-new plane for under $200,000”.
“From the point of view of an aircraft buyer [ LSA certification] is quite positive” says Mr Kitt. “people say, “well I’m getting on in life I don’t want to spend half a million or a billion dollars on an aeroplane but I can spend 200,000 with everything I want to get, autopilot, glass panels and ballistic recovery systems… we (now) have these highly equipped aeroplanes at a fraction of the cost of traditional GA aircraft.”
Recently, Tecnam, whose head operations reside in Capua, Italy, announced that it has a newly established corporate presence in Australia, which will be managed by its Australian sales team. Mr Walter De Costa, Tecnam’s worldwide sales director stated through an October media release that “after many years of successful operation, and with a brand-new product line to be offered in General Aviation, Tecnam has decided to confirm its presence in Australia and to sell and support its products directly”. The P2010, a larger, four seat relative of the Tecnam P2008 will be managed by Mr Allan Bligh together with his long-term associate, Mr Spencer Ferrier of Sydney. “We are really proud to commence our corporate presence in Australia with such a strong and capable sales team,” Mr Da Costa said. “The introduction of our heavier aircraft in the VH category will make a strong mark in Australian aviation and we look forward to serving the Australian travelling public with our well-proven, advanced design, economical fleet.”
There is a vast range of LSA aircraft available in Australia, manufactured both here and overseas. Companies like Anderson Aviation, the only distributor for the popular European BRM Bristell range of aircraft have homed in on the LSA market, with fixed or taildragger configurations and a generous bubble canopy. Brett Anderson, owner of Anderson Aviation was inspired to establish a distributorship in Australia for Czech aviation, BRM Aero after purchasing a plane from the company himself.
Smaller interior space is one of the disadvantages often attributed to LSA certified aircraft. But as each generation of aircraft comes to the fore, even the smallest details, like prioritizing comfort can make all the difference. By adding a little more legroom, the interior of the Bristell LSA has garnered a reputation for their deeper, wider cockpit where a goes a long way in terms of precious personal space.
Of course, single-engine aircraft aren’t limited to the piston configuration either. The first mention of a turboprop configuration in the public press was back in the February 1944 issue of the British aviation publication Flight, which included a detailed cutaway drawing of what a possible future turboprop engine could look like. The turboprop has come a long way since then, paired with the elite single-engined aircraft of today.
Turboprops, as mentioned before, are made up of far less parts compared to piston engines. This means that they more reliable mechanically and easier to maintain. Turboprop singles can fly higher, faster and further than piston singles, although the efficiency here drops off when a turboprop is operating at the comparatively low altitude of a single piston. Safety wise, turboprop aircraft have the means to feather the prop in the event of engine failure, a trait that it shares with the piston single, but sets it apart from its turbojet or turbofan relatives. Turboprops also produce considerably more HP than an equivalent piston engine and have a higher power output to weight ratio.
Turboprop engines are smaller and lighter compared to a piston engine, so they can maximise performance during take-off without wasting a whole lot of fuel on the side. But although turboprops fill the gap between pistons and jets – performing at maximum efficiency at mid-level altitudes and airspeeds may be of more expense and performance than most general aviation requirements. Operating altitudes may also add complications en-route, with icing and turbulence conditions that jet aircraft could climb above.
Daher’s TBM series has been an enduring presence in the skies. As a culmination of a collaborative development between Mooney and French company Daher, the design of the TBM family originated from the Mooney 301. In co-developing the larger turboprop design, designated as the TBM 700, the joint venture emphasised the design’s speed, altitude capacity, and reliability.
Upon its entry onto the market in 1990, the TBM 700 held the distinction of being the first high-performance single-engine passenger/cargo aircraft to enter production. TBM 700 quickly garnered success, capitalizing on the marked performance of a modernized turboprop design. This success quickly led to the production of multiple variants and improved models.
In October this year, Daher rolled out its 200th TBM 900 since the introduction of the upgraded 900 family in March 2014. The TBM 900 is the sixth evolution of the TBM 700 and makes no sacrifice in terms of speed. Retaining the title of the fastest GA aircraft to date, the 900 tops off at about 611 km/h. The TBM 930, one of the most recent aircraft offered alongside the 900, adds upgraded interior and avionics, including the Garmin G3000 touchscreen avionics suite. The aircraft is used by both private individuals, corporations and charter and hire companies looking to get to a destination without enduring a ride in economy.
So where is the single-engined aircraft headed in the future? According to Mr Kitt, the foreseeable future is looking pretty green. “I know my kids won’t be flying the same types of aeroplanes that I’ve been flying for the last 10 years” he says. “I reckon within the next 10-15 years we are going to see a big push for single-engine electric aircraft”.
Just this year, Siemens, the largest industrial manufacturing company in Europe used a modified Extra EA-300 acrobatic airplane, the 330LE, to set two new speed records. On the 23 March, the aircraft reached a top speed of around 340 km/h over three kilometres. And the very next day, at the Dinslaken Schwarze Heide airfield in Germany the aircraft also became the first electric glider towing aircraft.
“People keep saying that it’s ages away [but] I can guarantee that the way that technology moves so quickly…it’s only a matter of another decade,” predicts Mr Kitt. “We are going to see really reliable training platform electric aircraft. The technology is there, it’s just making the technology light weight, durable and reliable enough that we can start seeing type certified aircraft for training”. In the long term, Mr Kitt predicts that the electric market will create a big enough to open up the single-engine market “quite a bit over the next decade, especially with LSA because [aviators] are always looking at reducing weight and increasing reliability as well as functionality. If we can develop electric aircraft that are very low cost and are very reliable then it’s certainly going to be the way to go”.