Propellers, like wing spars, are among the few parts on an airplane that absolutely, positively, must not ever break. Under continual stress while absorbing engine power and converting it into thrust, the lowly propeller has to keep performing its function, year in and year out, witha scant attention paid to it. Catastrophic propeller failure immediately produces severe vibration as the engine continues to run with an out-of-balance prop, and the resulting stresses can lead to failure of the engine mount. If the engine departs the airframe, the airplane becomes uncontrollable due to the shift in CG. And yet, most of the time we just give the prop a light caress during our preflight inspection and say “Yep, it’s still there.”
Propellers deserve a little more respect. The design and creation of these exquisitely shaped rotating airfoils is as much akin to art as to science. The efficiency of some propellers can reach into the 90% range, as they screw their way into thin air while pushing or pulling the entire aircraft. Nothing could be simpler—or more complex. The simplest of all aircraft propeller types is, of course, the humble fixed-pitch two-blade airscrew, found on basic airplanes optimized for low-cost operation and uncomplicated piloting.
The term “propeller pitch” refers to the amount of forward motion that could theoretically be achieved in one revolution of the propeller under perfect conditions, assuming that it’s turning in a medium devoid of slippage or resistance. Think of a screw boring itself into soft wood. Usually expressed in inches, a propeller’s pitch is commonly quoted in conjunction with the diameter, as with a 72/56 prop being one with 72 inches of disc diameter and 56 inches of perfect forward movement in one revolution. For aircraft certification, propellers of a certain size and pitch are part of the approved equipment, and a minimum-permissible static (full-power runup) rpm may be specified as part of the limitations. Static rpm proves that the engine and propeller combination is capable of producing the thrust suitable for flight.
Proper choice of propeller pitch is critical to achieve maximum efficiency. There are actually several pitches and blade thicknesses existing in the twisted airfoil along the propeller’s length. The advertised pitch is usually measured at a midpoint blade station about 75% outward from the hub. At the blade’s tip, the speed of the airfoil’s movement through the air is vastly different than it is near the root, thus the tip requires a minimal amount of pitch and thickness as the effective speed nears supersonic flow. Tip speeds in excess of Mach .75 result in loss of efficiency. A propeller with too much angle of attack, or pitch, retards rotation and places an inordinate load on the engine. One with too little pitch, on the other hand, allows the engine to overspeed.
Changing airspeed away from a designed peak performance target results in less efficiency. At low speed, engine rpm may be limited by the large bite of a high propeller pitch, as in “high angle of attack,” while at a high diving speed, the rpm may rise to beyond redline as the engine becomes unloaded. Owners of airplanes with fixed-pitch propellers sometimes exchange props to maximize one or the other edge of the performance envelope, referring to a “climb prop” as one with a low pitch angle allowing extra rpm for takeoff, or a “cruise prop” with a higher pitch to optimize speed rather than climb.
The Best of Both
Obviously, it would be desirable to be able to change a propeller’s pitch, giving the best of both worlds without having to swap between two or more propellers. The first efforts to do this were ground-adjustable arrangements, with the blades held in a hub that permitted their shank to be rotated for pitch change. Such propellers are still available today.
In-flight pitch changing came next, using various methods of “shifting gears” from climb to cruise. The Koppers Aeromatic propeller, used on light aircraft of the 1940s, balanced centrifugal force against airspeed to adjust pitch for best performance without cockpit control. Aeromatic props may be returning to at least the experimental market; the rights to the design are now owned by Tarver Propellers in Fallon, Nevada.
Simple manual propeller-pitch shifting, adjusted by pulling or pushing a control to shift from a low-pitch takeoff/climb setting into a higher-pitched cruise position, was incorporated in the Hoffman Dimona motorglider I flew back in the 1980s. One idled the Dimona’s Limbach engine to reduce stress when making the change, and when the engine was shut down for soaring, a third position could move the blades into feather.
Controllable propellers, with variable pitch adjustment using an electric motor or oil pressure to position the blade angle, were developed in the 1930s to allow the pilot full control of optimum engine power, although rpm still varied with airspeed because the propeller was essentially in a fixed-pitch setting once adjusted. This shortcoming was alleviated by coupling the pitch-change mechanism to a governor that operated to automatically maintain a constant rpm, the constant-speed propeller in use today.
How Many Blades?
The best number of blades to use, frequently two blades versus three blades, is a frequent topic of discussion. With lower horsepower engines, adding an extra blade is largely a matter of sex appeal and noise conversion; all things being equal, a two-blade propeller is more efficient than an equivalent three-blade, although the three-blade prop will boost thrust at low airspeed during takeoff and climb. However, with increasing horsepower, extra blades will be needed to absorb the additional power. Both the disturbing quality of the perceived noise and the noise level itself are reduced by adding blades. And, adding a blade allows the same thrust to be developed with a shorter blade length, reducing tip speed to a quieter level.
Yes, there was a single-blade propeller. Built by Sensenich for the Everel Propeller Corporation in the 1940s, it was reportedly the most efficient propeller design. But its weird look, with a counterbalancing weighted stub on one side of the hub, kept it from becoming popular.
In experimental aviation, we are permitted to build any part of the aircraft, and that includes carving our own propeller; some dedicated individuals have done just that. Unless you are particularly gifted or inclined toward propeller fabrication, however, it makes more sense to purchase a ready-made prop from the dozens of suppliers specializing in them. A simple laminated-wood propeller is no longer sufficient for most homebuilts; carbon fiber blades, ground-adjustable pitch angles, and even in-flight controllable and constant-speed governing are available to maximize the performance envelope of our homebuilts.
Use of a non-certified propeller, even if the Lycoming or Continental engine is bone stock, usually requires an expansion of the Phase I flight testing period from 25 hours to 40 hours, just as would a non-certified engine. The effect of any pitch adjustments or other changes needs to be documented as part of the testing regimen.
Picking a Prop
As with choosing a certified Continental, Lycoming, or Rotax engine, there are a limited number of suppliers of certified propellers, perhaps five or six, which is the reason one finds Hartzell, McCauley, Sensenich, and MT propellers attached to most of the world’s certificated airplanes. Hartzell has been in the propeller business for over 100 years, and Sensenich isn’t far behind. Even the new kids on the block have a long history behind them.
However, the lower-horsepower kit and E/A-B airplanes can be equipped with propellers from a large number of companies. Some are handcrafted by cottage-industry entrepreneurs, each with their own following and specialties. Laminated wood predominates as the medium of choice for low-performance aircraft, but many prop builders are turning to composite materials as well.
A buyer’s guide of any type is bound to have some flaws in it, but we’ve attempted to cover the propeller industry as thoroughly as we can. In the accompanying tables, certified propellers are listed first, followed by the burgeoning list of non-certified propeller manufacturers. The tabulation includes contact information, the date of the company’s founding, types of construction, and horsepower range available.
Some of the larger propeller companies concentrate on type-approved props for certified engine applications, while the smaller firms market to the experimental non-certified user. And some are doing both, offering a line of certified props but also more than willing to build a custom non-certified propeller for a specific project.
Established propeller manufacturers may sell their products through a distributor or dealer network, through suppliers like Aircraft Spruce, Univair, Wag-Aero and SportairUSA, and aircraft kit makers may have distributor arrangements to supply props to their customers.
Certified Propeller Companies
Founded in 1969, GT has produced over 30,000 propellers. At last count, more than 200 propeller variations were available.
GT fixed-pitch propellers and variable-pitch propeller blades are made from a variety of laminated hardwoods that are reinforced with composite laminations. Many models comply with JAR/EASA 21P Rules.
Ground-adjustable LSA props are made with monolithic carbon technology and incorporate a metal strip to protect the leading edge. Two- and three-blade configurations are available for engines up to 110 hp. On ground-adjustable propellers for larger engines, GT uses the same blades found on their variable-pitch props.
GT also makes “old style” propellers for replica aircraft and original aircraft that date back to the 1920s-1940s. Although they follow original drawings, these props are often updated with modern airfoils.
Hartzell Propeller, Inc.
Hartzell has been in the propeller business for almost as long as airplanes have been flying. Robert Hartzell and Orville Wright were near neighbors in Dayton, Ohio, when the company made its first airplane propeller in 1917. Today, Hartzell supplies certified constant-speed propellers for nearly any propeller-driven airplane, including turboprops with six-blade configurations.
In addition to forged-aluminum blades, Hartzell has been making structural composite propellers since 1978 and is now building ASC-II (Advanced Structural Composite) propellers with carbon fiber laminates and a stainless steel shank. The Hartzell Trailblazer composite props feature a swept tip and are now available for 17 aircraft models, including the Bearhawk 4-Place and Patrol; CubCrafters XCub, Carbon Cub, and Top Cub; Glasair Sportsman; and Vans RV-8.
Sensenich Propeller Company
The venerable Sensenich Propeller Company, established in 1932, now operates as two divisions: the original company based in Lancaster, Pennsylvania, which makes only metal props, and a division in Plant City, Florida, that builds wood and composite propellers, established in 1999 to better serve airboat propeller customers.
Sensenich does just about everything in propellers; it still makes fine laminated wood props, it has ground-adjustable composite propellers for experimental and ASTM-certified LSA airplanes, and it builds aluminum two-blade fixed-pitch models for both homebuilt and certified applications.
The McCauley Propeller Systems division of Textron Aviation originated in 1938, introducing its first forged aluminum propeller in 1946. McCauley was purchased by Cessna Aircraft Company in 1960, hence its present ownership by Cessna parent Textron, which also owns the Beechcraft and Hawker brands. McCauley’s sales and engineering offices are in Wichita, Kansas, while manufacturing takes place in Columbus, Georgia.
Long a builder of certified aluminum-blade props in both fixed-pitch and constant-speed variants, McCauley is also experienced with composite propeller construction, supplying the composite two-blade propeller for the Cessna 162 Skycatcher Light Sport airplane. Among the composite prop projects on McCauley’s plate is a Black Mac Carbon five-blade reversible constant-speed propeller that will be on the Cessna Denali turboprop single.
MT founder Gerd Muehlbauer began working with composite propellers in 1968 and founded his company, MT-Propeller Entwicklung GmbH, in 1981. Based in Germany, MT propellers are well supported in North America by a service center in Deland, Florida, and other locations. Although primarily known for its “natural composite” propellers, some MT applications have an aluminum blade option.
MT-Propeller has extensive experience providing propellers for Experimental/Amateur-Built aircraft, from RV-4s to Lancair Evolutions. The company has supplied certified propellers for engines of 5000 hp, incorporating up to six-blade hub systems. In addition to hydraulic constant-speed propellers, an ELCOPROP electrically controlled propeller is available for engines up to 350 hp.
Non-Certified Propeller Companies
As would be expected, the world of propellers built specifically for experimental aircraft is expansive and active. The freedom to innovate and modify designs means a lot of choices are out there, in both materials and execution. Some propeller manufacturers have been in the same location for decades, others are more recent start-ups or continuations under new ownership.
Airmaster Propellers, Ltd.
New Zealand-based Airmaster offers a wide range of options in electrically controlled constant-speed propellers for experimental and ultralight-type aircraft. Their unique mode selector allows the pilot to dial in preset takeoff, climb, and cruise pitches, after which it holds the desired rpm with little interaction. Two- and three-blade hubs hold a variety of blade styles; Airmaster builds no blades of its own, providing complete propeller systems in collaboration with existing blade makers. U.S. resellers include Custom Flight Creations, The Airplane Factory, Kitfox LLC, RANS Aircraft, Kaolin Aviation Services and Arion Aircraft.
Arrowprop Company, Inc.
Primarily a builder of fixed-pitch wooden propellers for ultralight and light experimental airplanes, along with other specialty props, Arrowprop supplies props up to 72 inches in diameter. The Oklahoma-based company has been in business since 1961.
Based in South Australia, Bolly Propellers first established itself in RC (radio control) model aircraft as a supplier of wood and composite props, then branched out into full-size aircraft. Specializing in ground-adjustable carbon fiber blade construction, Bolly propellers are available in five Optima Series models for increasing horsepower ratings, using two-, three- and four-blade hub styles.
Craig Catto started Catto Propellers in 1974, building two- and three-blade fixed-pitch props for a variety of non-certified applications. Construction utilizes a wood core encapsulated with structural composite overlay. Catto Propellers has achieved ASTM certification to equip Light Sport Aircraft with its props. Optional electro-formed nickel leading edges create a durable leading edge for the blades.
Competition Aircraft, Inc.
Also known by its primary product name, Ultra-Prop, Competition Aircraft has long been a builder of ground-adjustable composite props for ultralights, trikes, gyrocopters, and powered parachutes with engines up to 50 hp. It is now producing the Ultra-Prop II, a carbon fiber reinforced propeller for applications of 25 hp per blade at about 2500 rpm, making it suitable for engines up to 100 hp. The 66-inch diameter Ultra-Prop II can be furnished in two-blade to six-blade configurations.
Valley Engineering, suppliers of Culver Props, bought the Culver propeller company in 2000 to complement its line of ultralight and light E/A-B airplanes. The two-blade fixed-pitch props are available for engines up to 300 hp, using laminated maple, mahogany, birch, and cherry wood. Much of Culver Props’ expertise is devoted to replica propellers for WW-I and antique airplanes, including scimitar shapes favored by those early planes.
The DUC line of forged-carbon composite propellers from France carries European Aviation Safety Agency certification and is available for a wide range of ultralight and experimental aircraft up to 140 hp. DUC Hlices’ ground-adjustable propellers come in “Swirl” and “Windspoon” models, the former reportedly giving a constant-speed effect for higher speed airplanes, while the Windspoon is designed for slower aircraft.
Based in British Columbia, Canada, GSC makes its Tech Series wood propellers in fixed-pitch and ground-adjustable styles, and it also builds a GSC-GTA in-flight adjustable-pitch prop, using a mechanical adjustment. The GSC-GTA can be supplied with either GSC wood blades or Warp Drive composite blades. An 18-degree adjustment is possible. Fixed-pitch propellers are available in 32- to 72-inch diameters. GSC focuses largely on Rotax engine applications, including powered-parachute propellers.
Ivoprops are widely known for the torsion rod embedded in each blade, allowing pitch adjustment by tightening or loosening the adjustment rod to slightly twist the blade. The Ivoprop Magnum propeller can be manually adjusted on the ground or fitted with an electric in-flight variable-pitch control in the cockpit. Ivoprop’s latest innovation is an electronic governor for constant-speed operation. Blade construction is carbon fiber composite, finished with black gelcoat and a stainless steel leading edge. Two-, three-, or six-blade systems are available.
Performance Propellers USA, LLC
Frank Johnson’s Performance Propellers company supplies two- and three-blade CNC-cut laminated wood propellers for experimental and aerobatic aircraft. Custom tweaking is provided, allowing the customer to test-fly and return the prop for changes after static and max rpm are verified. A rainproof leading edge and fiberglass tips are then installed, along with a clear finish.
Powerfin builds ground-adjustable carbon fiber propellers for a variety of light experimental aircraft, primarily for Rotax engine installations. Hub styles for up to five blades are available, and the company is working on a six-way hub for drone use. Powerfin denotes its products as “professionally designed, handcrafted,” with over 20 years of experience producing propellers.
Prince Aircraft Co.
Lonnie Prince has been in the propeller business since 1979, building custom props for everything from ultralights to NASA wind tunnels. Prince props are created from rock-hard laminated maple and carbon fiber laid over a wood core, and feature a scimitar shape that produces an aerodynamic pitch change as speed increases, reportedly a four-inch change in pitch from takeoff to cruise. The famous P-Tip option remains available, delaying the tip vortices by curling the prop tip to create the effect of a longer blade length.
Oregon-based Jeff Bertuleit has been carving fine wood propellers since 1984 for homebuilts and ultralights. He focuses primarily on two-blade fixed-pitch props for E/A-B airplanes up to 260 hp. Props, Inc. propellers are made from laminated eastern maple and are up to 35 pounds lighter than a constant-speed prop. As Bertuleit points out, wood’s natural damping avoids having rpm restrictions.
Ed Sterba started carving handmade propellers in 1980, initially focusing on props for converted Volkswagen powerplants, and he’s still producing his beautiful laminated wood two-blade fixed-pitch propellers. Sterba Propellers are available for engines up to 200-hp, as used in the RV kit aircraft series.
The legendary Aeromatic propeller, with its automatically shifting blade pitch and blade construction using wood core and laminate overlay, has a long history dating from the 1940s. The Aeromatic’s principle of aerodynamic shifting of propeller pitch, with no pilot interaction required, was popular for postwar planes until the general aviation collapse in the late 1940s. The rights to the Koppers design is now owned by Kent Tarver of Fallon, Nevada. At this point, no certified production is planned, but new Aeromatic props for the experimental aircraft market are under development, with one currently flying on a VariEze for testing.
Tennessee Propellers, Inc.
Although it’s now based in Georgia, just outside Chattanooga, Tennessee Propellers continues to supply two-blade fixed-pitch wood props for ultralights and small experimental aircraft, along with propellers for airboats and other users. Construction is of rock-hard maple, using resorcinol-type glue and finished with a two-part polyurethane coating.
Warp Drive, Inc.
Warp Drive propellers have been in production since 1989. They are well-regarded ground-adjustable props with solid carbon blades. Many of the Warp Drive blades are fitted into other brands of ground-adjustable hubs. Warp Drive markets primarily to ultralights, trikes, gyrocopters, powered parachutes and light experimental planes, along with airboats and other users. Two-, three-, and four-blade styles are available.
WhirlWind Propellers Corporation
WhirlWind Propellers makes carbon fiber ground-adjustable propellers for the experimental aircraft market in two- and three-blade styles. Whirl Wind Aviation is the company’s constant-speed propeller division. WhirlWind blades are used by some other brands of ground-adjustable props, showing the esteem to which they are regarded in the industry. The company also offers such diverse products as replacement blades for Russian Vperod propellers on the M-14P engine.
We trust that you’ll find this overview of the propeller industry useful. Help us keep it up to date by passing along changes or corrections to firstname.lastname@example.org.
|Company||Year Founded||Construction||Horsepower Range|
|GT-Propellers||1969||Wood and composite||30 to 2500 hp|
|+39 0541 693399|
|Via del Commercio, 7 47838 Riccione (RN) Italy|
|Hartzell Propeller, Inc.||1917||Metal and composite||up to 2,180 hp|
|One Propeller Pl, Piqua, Ohio 45356|
|McCauley Propeller Systems||1938||Metal and composite||100 to1,200 hp|
|10511 East Central, Wichita, KS 67206|
|MT-Propeller USA, Inc.||1981||Natural composite||up to 5,000 hp|
|1180 Airport Terminal Dr, Deland, FL 82424|
|Sensenich Wood Propeller Co.||1932||Wood and composite||50 to 275 hp|
|2006 Wood Ct, Plant City, FL 33563|
|Sensenich Propeller Mfg. Co. Inc.||1932||Metal||65 to 200 hp|
|14 Citation Ln, Lititz, PA 17543|
|Company||Year Founded||Construction||Horsepower Range|
|Airmaster Propellers, Ltd.||1999||Metal/composite||80 to 200 hp|
|20 Haszard Road, Massey, Aukland 0614, New Zealand|
|+64 9 833 1794|
|Arrowprop Company, Inc.||1960||Wood and composite||up to 100 hp|
|P.O. Box 610, Meeker, OK 74855|
|Bolly Aviation||1978||Composite||15 to 180 hp|
|Hangar 1 Calvin Grove Airfield, Virginia, South Australia 5120|
|+61 8 8380 8396|
|Catto Propellers||1974||Composite||65 to 300 hp|
|Jackson Westover Airport|
|12370 Airport Rd, Jackson, CA 95642|
|Competition Aircraft, Inc.||1984||Composite||up to 100 hp|
|10925 Shire Ct, Grass Valley, CA 95949|
|Culver Props||1983||Wood||up to 300 hp|
|15685 Co. Road 7100, Rolla, MO 65401|
|DUC Helices||1997||Composite||100 to 160 hp|
|Aerodrome de Villefranche-Tarare, 289 Avenue Odette & Edouard Durand, 69620 Frontenas, France|
|+33 0-4 74 72 12 69|
|GSC Systems, Inc.||1984||Wood||35 to 115 hp|
|#8 2440B 14th Ave., Vernon, BC Canada V1T 8C1|
|Ivoprop Corporation||1986||Composite||up to 700 hp|
|2615 East 67th St, Unit E, Long Beach, CA 90805|
|Performance Propellers USA, LLC||2009||Wood||50 to 300 hp|
|466 Pr 5832, Donie, TX 75838|
|Powerfin Propellers||2008||Composite||up to 160 hp|
|705 S. 5300 W., Ste 4-5, Hurricane, UT 84737|
|Prince Aircraft Company||1979||Wood and composite||100 to 300 hp|
|6774 Providence St, P.O. Box 2669, Whitehouse, OH 43571|
|Props, Inc.||1984||Wood||up to 260 hp|
|354 S.E. 2nd St, Newport, OR 97356|
|Edward Sterba Propeller Company||1980||Wood||30-200 hp|
|9660 Southeast 72nd Ave, Ocala, FL 34472|
|Tarver Propellers||2003||Wood/composite||up to 170 hp|
|15009 Rio Vista Dr, Fallon, NV 89406|
|Tennessee Propellers, Inc.||1981||Wood||28-100 hp|
|7031 Highway 157, Rising Fawn, GA 30738|
|(see Competition Aircraft)|
|Warp Drive, Inc.||1989||Composite||up to 180 hp|
|1207 Highway 18 East, Ventura, IA 50482|
|Whirlwind Propellers Corp.||1973||Composite||80 to 400 hp|
|1860 Joe Crosson Dr, El Cajon, CA 92020|