The exhaust on a PT6A adds additional thrust, not total waste, whereas exhaust on a piston engine thrust is negligible. 12 built as new-builds by Canadair for RCAF as CC-109 in 1960 for £436,000 per-aircraft. Second- turbine engines produce their work differently and tend to need more fuel per horsepower because of how the engines work. Where the process of combustion in a piston engine occurs in individual, distinct ignition events, a turbine engine is ingesting and compressing air, accepting fuel, and igniting that mixture continually—a piston engine might be considered a ‘rapid explosion’ device, while a turbine is a ‘continually exploding’ power source. It operates at much higher temperatures, and the turbine spins as fast as 45,000 rpm, so a turboprop engine must be constructed of extremely heat-resistant metals and be very well balanced to handle rotational forces. Predictably, converting a piston airplane to turbine power wasn’t exactly a slam dunk. Shorten block-time up to 25%. High altitude or low, it’s vital you fly the aeroplane precisely. The 36 Model Bonanza introduced in the late 1960s is the foundation for the Tradewind conversion. As one measure of the quantum leap in complexity, count the circuit breakers in even a pressurised piston twin, and compare that to the number in a SETP. When transitioning, then, you’ll need to become comfortable and capable in a medium- to high-altitude environment. Great avionics, Garmin 430W, GTX 345, STEC 55 … The approach is almost as old as powered flight: improve a proven airframe by grafting on a better powerplant. But there are significant differences in the way you’ll fly a turboprop—and only some of them are related to the engine itself. In a turboprop you are still a pilot, but you are just as much a systems manager. That’s simple enough to grasp. Higher altitude equals lower power. Save my name, email, and website in this browser for the next time I comment. Even without converting this to distance in centimetres, you can visualise a wide variety of performance and handling with variations within the allowable centre of gravity envelope. The new IO-550A engines improve single-engine service ceilings as well as improved rate-of-climb and cruise airspeed. For decades, the drumbeat has been steady—turbine airplanes are unobtainium as private aircraft. Going to turboprop from piston involves some interesting balancing acts because of different aspects of the engine going in and the engine coming out. In a turboprop, by contrast, exhaust is the primary product. For example- compared to the piston powerplants they replace- turboprop engines generally weigh less per horsepower delivered. And that per-hour basis should be nicely offset to a per-mile degree by the higher true airspeeds available. Both engine types propel their airframes with greater fuel efficiency up high than down low. More information from www.tradewind-bonanza.com. Complete Strip and Paint, 3 Stage Pearl Paint. With that in mind let’s take a quick look at the types of mishaps that have occurred in our three sample turboprop marques from the ATSB record: You can see that the things that lead to crashes in SETPs are not much different from the factors involved in piston aeroplane crashes. But typically the turbine engine makes far more power – particularly flying low – and doesn’t achieve its best economies until up high. Following- we’ll look at three of the betterknown and longer-running conversions on the market- recognizing that others exist – and that more will be coming in the future. Interestingly- the difference in fuel consumed by the piston original making 235 knots and the Royal conversion’s best cruise amounts to a mere 10gph. Finally- the time to overhaul for piston aircraft generally comes far earlier than in turbine engines- adding a significant attraction to the appeal of turbine engines. A Colemill conversion is much more than an exchange for more powerful engines. Some jet thrust is also produced by exhaust leaving the turboprop engine. Rocket Engineering’s most popular mod is the JetProp DLX conversion of the Piper Malibu and Mirage, which replaces the piston engine with a Pratt & Whitney PT6. A turbopropeller engine (turboprop) is similar to the piston engines with which you’re likely familiar, in that both types are internal combustion engines. Going to turboprop from piston involves some interesting balancing acts because of different aspects of the engine going in and the engine coming out. It needs about 2-550 feet of take-off space to clear a 50-foot obstacle and climbs at about 1-200 fpm. Weight and centre of gravity range. The advantage at altitude is what gives turboprops such appeal. Sign up for free aircraft sales alerts and digital aviation magazines now. Currently you have JavaScript disabled. For more information view our updated Privacy & Cookie Policies. As the aeroplane climbs and power output decreases, you may be able to advance the power lever to maintain or even increase power in climb, as long as the engine stays within all three of its limits. In aviation- the quest never ends to make airplanes better- more efficient- more capable- and always faster. Wing loading is the weight carried by its wing area. Turboprop Aircraft (0) Piston Single Aircraft (3) Piston Twin Aircraft (0) Like piston twin aeroplanes, SETP propellers are featherable. And while the more-powerful engine may offer the ability to lift more- a higher operating weight can introduce issues into the capacity of the landing gear- wings and other airframe structures. The P-51H (NA-126) was the final production Mustang, embodying the experience gained in the development of the XP-51F and XP-51G aircraft. In some instances- converting to a different brand engine or to a different type provides the same benefits. The Colemill Bearcat conversion for the Cessna 310R improves the aircraft's performance significantly. And if a twin-engine piston is more what you were thinking O&N offers those same Rolls-Royce turboprops in a pairing on the Cessna 340, converting the piston twin … Thomas P. Turner describes how to lift your game to match the demands of the ultimate propeller-driven aeroplane type. But that price differential no longer remains consistent or reliable. The airframe modifications to the Malibu are largely limited to those required to accommodate the engine and its fuel needs that make it a JetPROP DLX. The base airframe converted provides the main foundation for the success of the JetPROP DLX: a strong single with a pressurized cabin. With their abundance of power, both airplanes are bucking against their respective redlines at lower altitudes. While not something widely embraced- the customer-base has proven large enough over the years to support some long-term programs. With that mastery you should be able to avoid accidents, right? More information from www.royalturbine.com. The TBM900’s allowable CG range varies by 24 centimetres. Turboprop Power by Rolls-Royce Today’s highest performing and most economical general aviation aircraft are the single engine turboprop (SETP) class. The problem that accompanies this idea stems from the fall-off in engine output as altitude increases. Sometimes it is also called a prop-jet. It was successes like those with the DC-3 that helped inspire developers to design turboprop conversions for a wide range of airframes with strong appeal to the owner-pilot business aviator. Lower air pressure reduces the efficiency of engine-inlet pressures- which cuts power output. Over successive generations of conversions- the DC-3 and its military variant- the C- 47- received new leases on life- thanks to the improved performance available: Higher speed- greater lift- better runway performance – all the points that hold appeal for pilots and operators- particularly those operating in remote areas where aviation gasoline remains rare to non-existent even today. The Tradewind Bonanza turns in 220 knots true at 15-000 feet- with range potential out to 900 nautical miles. Piston twins, he added, are capable but get a bad reputation. You’re about to transition into a single-engine turboprop (SETP). The power of a turboprop is measured in shaft horsepower (SHP). Besides the great equalizer of human stupidity (insufficient fuel, improper procedures, flying into bad weather, etc) the piston twin doesn't have a lot going for it. Original designed and built during the WWII era and equipped with radial engines, it was converted to turboprops some 40 years ago . Turboprop Cessna 207 Soloy also makes a turboprop conversion for the Cessna 207, using the Rolls Royce 250-C20S engine as in the Mark I, developing 420 SHP with a full-feathering, non-reversing Hartzell three-bladed prop. JetPROP got its DLX to market ahead of Piper’s launch of its turboprop remake of the Malibu (the Meridian) and they both compare closely in some areas. The higher the wing loading the higher the stall speed. The condition lever controls engine speed and fuel flow. The approach is almost as old as powered flight: improve a proven airframe by grafting on a better powerplant. Take-off and landing speeds increase, and climb speeds decrease, as a result. Piston engine power is measured in horsepower (HP) and is determined by manifold pressure, propeller speed and fuel flow. Fixed shaft turboprops, in which the propeller is directly connected to the engine and rotates any time the engine is running, use a power lever (sometimes called thrust lever) and a condition lever. First flight February 9, 1955. Runway performance improves dramatically as you’d expect from the higher climb performance- and the speed difference and range potential both improve greatly- as well. Compare that to the Malibu’s 350 maximum horsepower- which drops about 20 percent at cruise altitude. It is also very useable at altitudes that require oxygen up to 25-000 ft. Studies on hypoxia, supplemental oxygen use, high-altitude navigation and meteorology are just as important in your studies as the aeroplane’s flight manual. GETTING PLACESFor many a year- Jet-A sold for less than aviation gasoline- adding to the appeal of going to a jetprop engine. Once a turbine engine starts, the igniters are turned off; ignition is constant as air and fuel are continually fed to the engine and the fire continually burns. Cost for the conversions was £160,000 per-aircraft. From 1970 to 1984, Frakes converted 8 Mallards while in Texas. For example- climbing to the Tradewind Bonanza’s optimal altitude will take the Bonanza more than 15 minutes- while the converted airplane needs less than five. In order to post comments, please make sure JavaScript and Cookies are enabled, and reload the page. As noted just above- the fuel requirements increase for same-distance trips- so somehow the converted aircraft needs to offer greater fuel capacity – and more fuel means accepting more fuel weight - a factor complicated by the heavier weight per gallon of Jet-A. Between these differences and other issues the difference in fuel needed may work out closer to 25-30 percent on a per-hour basis. While rare in piston aircraft- however- engine failures are statistically even lower in turbine aircraft- providing yet another element that helps compel the buying decision for some. Let’s look at the variables to get at least a basic idea of the differences. You’ll reverse the propeller by pulling the power lever all the way aft and over a stop. Everything you do (and are supposed to do) in piston aeroplanes—airspeed control, attitude control, rudder coordination, systems knowledge, checklist use—is even more important when you fly a SETP. The reality, however, is that knowing how the engine works is a small part of flying a turboprop. Higher altitude equals lower drag. Several companies tackled such conversions over the years- among them Bassler in Oshkosh- Wisconsin- and Conroy Aircraft in Santa Barbara- California. Also, you will lose flexibility: in a piston-powered PA46 you simply fly a lot lower if on FL250 you'd have have an 80-knot headwind blowing. The CG range of the Cessna 208 Caravan, a true freight hauler, is 55.7 centimetres. It’s usually beneficial to compare what you’re learning to what you already know. In aviation- the quest never ends to make airplanes better- more efficient- more capable- and always faster. And the ones to succeed and build a market generally enjoy strong- loyal followings from their customers. By using our site, you consent to our use of cookies. For example- compared to the piston powerplants they replace- turboprop engines generally weigh less per horsepower delivered. Individually, piston engines are far less reliable than turboprops. What this means is converting to a turbine from a piston with equal horsepower requires carriage and use of more fuel – in the 20 percent range- horsepower-for-horsepower. Most, but not all, SETPs are pressurised. The Royal Duke employs the D60 airframe produced between 1974 and 1982- and the conversion involves either the PT6A-21 or -35 engines- with new props- as per the other conversions covered here- and other changes to cover the engines’ fuel and monitoring needs. Free turbine engines have three engine controls: the power lever, setting pressure or torque output; a propeller RPM control, adjusting propeller speed (generally much slower than piston propeller speeds, usually 1500 to 1900 RPM); and a condition lever that is basically on ON/OFF control for the fuel. And it always ignored a couple of realities of turbine operations: First- kerosene- Jet-A and the like boast heat contents far lower than gasoline - so all other things being equal- an airplane powered by Jet A needs more fuel to produce the same amount of work. THE TRENDSETTERAn early target of propjet conversions back in the 1960s – when turboprop engines were coming of age – was an aircraft plentiful and well-regarded: the Douglas DC-3- arguably the world’s first successful airliner and a backbone machine for ops from Normandy to the Outback. AND THEN THERE’S APPROVAL…Finally- once the developer of such an upgrade feels the issues have been worked out satisfactorily- the revised airplane must emerge from the rigors of earning a Supplemental Type Certificate. There are several characteristics of most SETPs that cause them to fly differently than the piston aeroplanes with which you’re more familiar. In 2002, Conrad and Sadler launched into a development program to replace everything from the firewall forward on the prototype Duke. Piston Engine Aircraft vs Turboprop Engine Aircraft Piston engine, or reciprocating engines, are related to the steam engine, which was first introduced in the early 17th century. The piston engines on the Duke are expensive maintenance hogs. Higher wing loading increases stability and reduces the impact of turbulence, but it often also results in higher stick forces—the aeroplane ‘feels’ heavy, and it takes more effort to manoeuver. The conversion installs a Pratt & Whitney PT-6A turbine engine and a Hartzell four-bladed reversible propeller. The Bonanza does need considerably more fuel capacity- and Tradewind accomplishes that with a set of distinctive tip tanks with integral winglets for efficiency. Interestingly- however- the JetPROP DLX compares favorably with the Meridian in most areas- including speed- range- maximum altitude and payload- at 350 pounds. TRADEWIND TURBINES: TRADEWIND BONANZAThe honors for longest production run for a civilian airplane go to the Hawker Beechcraft Bonanza- which started life as the Model 35 in 1947. Performance with the 250 turboprop engine marks a dramatic break from that of the piston-powered Bonanza. N46CS has 4650TT with 1850 since the Turbine Conversion 365 since HSI. The conversion costs for a Malibu owner makes the proposition a well-below-one-million way to own a fast- comfortable- flexible turboprop single. Notify me of follow-up comments by email. Familiar piston aeroplanes have fairly narrow CG ranges. Aeroplane stability and performance are determined in part by the location of its centre of gravity (CG). Unlike its singleengine kin- with full fuel the Royal Duke remains a genuine hauler- with 750 pounds of payload available. Shaft horsepower is a function of propeller RPM and the force (torque) applied to the propeller shaft. So let’s compare and (primarily) contrast piston-engine and turboprop engines. A turbopropeller engine (turboprop) is similar to the piston engines with which you’re likely familiar, in that both types are internal combustion engines. Performance achieved with a Rolls-Royce Turboprop Engine conversion by Soloy Aviation. Join Date: Nov 2001. During engine start you must watch for a ‘hot start’ condition, that is, exceeding temperature limits, and immediately shut down the engine if it overtemps (the term is the same, but this is completely unrelated to ‘hot starts’ in fuel injected, piston engines). In some instances- converting to a different brand engine or to a different type provides the same benefits. But the 3-600-hour engine overhaul cycle for the P&WC powerplants is more than twice as long as the Duke’s original engines. - Airfleet Capital Finance Offer - US only. Work-arounds to these two factors have often involved longer engine mounts so the lighter engine works within the weight-andbalance needs. Neither the Malibu nor the JetPROP DLX win any contests for the full-fuel payload needed to cover their 1-000-mile maximum leg. A piston engine’s ignition system operates the entire time the engine is running, providing spark to the cylinders. Tradewind picked the highly regarded- light and compact Rolls-Royce Allison 250- flat-rated to 420 horsepower- and since the Bonanza lacks pressurization- Tradewind focused on providing a performance increase with the Rolls-Royce Allison due to it's low fuel consumption at non-pressurized altitudes. Fillipini counters, “For trips under 500 miles or to access to runways not accessible to jets, a turboprop or piston aircraft is often the preferable and sometimes the only option.” He notes, “For these short hops, the speed advantage of a jet is nullified by the fact that the aircraft doesn’t spend much time at cruising altitude. Superchargers- driven by the engine itself- and exhaust-driven turbochargers both have the benefits and their devotees. Jet thrust usually accounts for less than 10% of a turboprop’s total power output. Engines used were Rolls-Royce Mk. By comparison- the Bonanza with its piston engine can cover only about 730 nautical miles in the same time needed by the Tradewind-converted Bonanza to fly 900. The Preferred Turbine -3 conversion takes this great airplane and makes it even better.With increased speed, higher payload and technical advancements, the Preferred Turbine -3 will get the job done safely and efficiently. Add them together and you odds for … An issue piston and turbines also share involves fuel efficiency. In a turboprop engine, a turbine (jet) engine shaft is connected to a reduction gear box and propeller governor, which in turn governs propeller speed and operation. Power loading. Textron Aviation’s new unpressurized Cessna turboprop twin can be configured for up to 19 passengers or all-cargo operations. Congratulations! Since turboprops generally have much more power than piston engines, however, they still tend to outperform turbocharged piston aeroplanes at most altitudes. That gives the airplane the ability to fly more than 1-000 statute miles in under 4.5 hours. Leaning is not required in any turboprop engine, but is controlled automatically when the pilot sets the power lever. The PC-12’s CG range is from 27% to 44% of the MAC. It spins turbines that in turn drive gears spinning the propeller (to generate thrust) and the engine’s compressors (for combustion). Both the JetPROP and Piper turboprops employ the wildly popular PT6A turboprop engine from Pratt & Whitney Canada: the DLX got the PT6A-35 flat rated to 560shp; for the Meridian it’s the PT6A-42 flat rated to 500shp. The higher the power-to-weight ratio, the faster the aeroplane will accelerate, climb and cruise. As with the Mark I, cruise RPM is 1810. And that’s what we examine this month: converting to turboprop power from a piston airplane - or from one propjet brand to another. You'll find economy cruise power settings commonly at and below 65% of total power in piston airplanes. Unlike piston aeroplanes, in which ‘full throttle’ is almost universally correct for take-off, in turboprops it is almost never appropriate to push the power lever to the forward stop. Turbine engines are remarkably compact and lightweight compared to piston mills. However, the Duke has a problem – er – two problems. Great reading on the differences between piston engine and turboprop aircraft but with their inherant similarities given they are both internal combustion engines which also have some rather different operational characteristics! There are limits on reverse thrust, so you’ll have to use this capability carefully. 1. 3. Maintenance, including airframe, engine and APU, is estimated to cost $447.55 per hour. Nope, only corporations and the well-to-do can burn Jet A. JetPROP- LLC developed the DLX around the long-running Piper Malibu/Mirage- sporting a 350-horsepower piston engine with dual turbochargers- providing breathing for its high-altitude abilities and cabin pressurization. Piston engines are controlled by throttles, propeller RPM, and fuel mixture controls. It’s important for you to know, however, that turboprop aeroplane performance decreases with increases in density altitude. It’s been said that everything about flying light aeroplanes applies to heavier ones, but not everything about heavy aeroplanes applies to lighter ones. Click here for instructions on how to enable JavaScript in your browser. 1979 Cessna 182Q, 2800TT, Full Restoration In 2015, 200 Hours Since. New cowls- streamlined exhaust stacks- engine instrumentation- and other modifications give the converted Royal Duke significant performance potential: 292 knots true burning 67gph fuel at FL270. But whatever the decision- the added load must also work within the weight-and-balance envelope. A problem for them is the maintenance involved and the excess temperatures produced by the act of compressing the air. A comparison of the wing loading of familiar piston-powered aeroplanes, the Cessna 172 and Beech Baron 58, and popular SETPs, the Cessna 208 Caravan, TBM 900 and Pilatus PC-12, tells us that performance and handling will be noticeably different when you transition to turboprop aeroplanes. You’ll be required to complete stringent training before you’ll captain a SETP. It’s the only twin-engine turboprop on this list, so it burns more fuel than the others at 101.7 gallons per hour, which, at $5 per gallon, is $508.50 per hour. Video: Field of dreams: Daher TBM’s latest  SETPs, the TBM 930 and 910 at Oshkosh, in the US. The Meridian received far more rework en route to its transition from the Malibu – even though they are quite similar in appearance. For the pilot without a Malibu- the cost can vary and still beat those of a new Meridian by several hundred thousand dollars – though the panel of a new Meridian may have the JetPROP devotee thinking about spending some more to gain similar technology and capabilities on top of the basic DLX package. “Turbocharged” refers to piston engines only, whereas a turboprop is a jet engine that turns a propeller. At first you might think the added power of a turboprop means you can get away with a little sloppiness, especially during take-off and landing. This permits you to direct thrust forward, instead of rearward, to dramatically shorten landing distances. Therefore, as the aeroplane goes up in altitude and the ambient air pressure decreases, the turboprop’s power output decreases as well—turbines are normally aspirated engines. Downtime during aircraft conversion “There’s also the downtime of the aircraft to be considered,” Nel explains, saying that If the operator is converting from an older model turboprop to a newer turboprop that’s roughly the same physical size, it usually takes about a month to conduct the conversion … Beginning in 1970, the late J. Fred Frakes began engine conversions from early radial piston power to Pratt & Whitney turbine engines. Turbine Bonanzas suffer from limited payloads because of the extra fuel required to feed the turboprop; with full … THE CONSIDERATIONSFor decades back- aircraft engineers and designers recognized that putting aircraft in higher- thinner air offered the potential to fly faster. New Hartzell 3 Blade Prop 50 Hours Since Installed. Wing loading. You have entered an incorrect email address! Turboprops come in two basic designs: fixed shaft and free turbine. All turboprops are more efficient above 10,000 feet. A turbine engine compresses air, but the amount of compression is usually fixed. 510 and Dart turboprops- and the Pratt & Whitney Canada PT6 line coming into vogue. I'm also familiar with some of the drawbacks that are generally associated with piston to turbine airframe conversions, and while I don't dispute that those drawbacks often do exist, I'm not particularly concerned with generalization drawn from the whole of the turboprop conversion fleet. In contrast- the Bonanza makes its 170-knot best speed at about 7-500 feet- and by 13-000 the speed available is off by more than 30 or more knots. Turbine engines suffer from the same power-loss phenomenon- but because of how they work they continue to provide strong power to altitudes that let them eke out the maximum in speed while driving the airplane. Since then, Rocket has shifted to turbine conversions, realizing that avgas for piston engines may someday become extinct. Turboprops have strict operating limits of torque, internal temperature and rotational speed. The first difference is the engine. The reality is that even flown precisely, turboprops typically use more runway than piston aeroplanes. This aircraft, with minor differences as the NA-129, came too late to participate in World War II, but it brought the development of the Mustang to a peak as one of the fastest production piston-engine fighters to see service. 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