experimental aircraft

The Ins & Outs Of Experimental Aircraft

The popularity of working with one’s own hands to take to flight began long before the Wright brothers ever started experimenting in Kitty Hawk. Flying machines were being thought up, experimented with, and attempted long before the settlers colonized the U.S.

But, unfortunately, those early “homebuilt” machines weren’t always safe. To make these machines safe, the government found it necessary to have some oversight. That oversight began in October of 1952. 

For the first time, the U.S. government included an “experimental” amateur-built category in the Civil Aeronautics Manual. Perhaps not so coincidentally, it was around this same time, in January of 1953, that the Experimental Aircraft Association was founded in Wisconsin.

At Stockton Propeller, we love the challenge of working with our experimental aircraft customers and on their custom aircraft propellers. If you’re looking for someone in the Northern California/Nevada region to work on your homebuilt’s propellers including to repair the propeller blade, contact us today.

What Is An Experimental Aircraft?

“Experimental” is the Federal Aviation Administration (FAA) designation for amateur-built or homebuilt aircraft. The “experimental” identification has been around for over 60 years. 

It’s an aircraft used for non-commercial or recreational purposes, such as education or personal use. The term refers to the FAA category for the airplane’s registration, not the exclusivity of the plane’s design or the aircraft’s use. 

Suppose an individual builds at least 51% of an aircraft. In that case, one may register the plane in the FAA’s “Experimental” or amateur-built category. 

Builders can work from kits (with parts of the airplane fabricated) or plans (where the builder purchases all the pieces and then assembles them). 

These amateur-built, or experimental, airplanes are also commonly referred to as “homebuilts.” The name is obvious because many individuals construct aircraft and custom aircraft propellers at home. Construction often occurs in their garages or other outbuildings.

There are currently over 32,000 amateur-built aircraft licensed by the FAA. They have been registered and flown safely for many years.

Curiously, the FAA’s “Experimental” category also includes approximately ten other subcategories. These include aircraft used for crew training or air racing. They also have historic aircraft (such as World War II military aircraft) flown in air shows and exhibitions.

Experimental aircraft are not the same as “ultralights.” Ultralights are one-person flying machines operating under a completely different set of federal regulations. 

Amateur experimental aircraft and homebuilt custom aircraft propellers are registered with the federal government in the same manner as production aircraft with corresponding “N-numbers” on the fuselage.

Who Builds Experimental Airplanes?

There isn’t just one demographic for those interested in taking on this project themselves. Builders include astronauts, airline pilots, military jet pilots, mechanics, machinists, welders, professional people, and many others.

Why do they build them?

There’s a variety of reasons why someone chooses this particular DIY project. 

  • They could see it as a personal challenge
  • They may want to educate themselves more on the “nuts and bolts” of flying
  • They could be seasoned pilots looking to increase their performance in the skies
  • They may want to invest some “sweat equity” into custom planes and airplane propellers instead of purchasing a manufactured aircraft. 

While a few homebuilt airplanes are custom or original designs, the vast majority of builders use standardized, tried-and-true kits or plans. These plans or kits are constructed successfully by the hundreds, if not thousands.

What Goes Into Building Your Airplane and Custom Airplane Propellers?

Most enthusiasts will tell you that it’s a lot of blood, sweat, and tears.

The cost of building your airplane range may range from under $10,000 to more than $100,000. Many factors contribute to this price variation, including your desired performance characteristics and any optional engine and avionics packages you choose

For comparison, a new factory-built Cessna 172 costs more than a quarter of a million dollars. 

Many homebuilts utilize composite materials that help create lighter, faster, and more fuel-efficient airplanes than similar production aircraft.

It can take a while, however….

Building an amateur aircraft and your custom airplane propellers will take somewhere between 1,000 and 3,000 hours to complete, on average.

Some individuals complete their airplane in less than a year. Others may take a decade or more.

A Few “Extra” Facts About Experimental Aircraft

  • Experimental aircraft are regulated, just like manufactured aircraft. The plane still has to be registered with the Federal Aviation Administration, inspected by an FAA inspector, and issued an airworthiness certificate.
  • An amateur-built airplane is subject to the same condition inspections every 12 months as small production aircraft undergo.
  • You don’t need a license to build your aircraft; all you need is the will fly one! To fly, you must earn and maintain the same federal pilot’s training and ratings as those who fly factory-built aircraft, including Pipers, Cessnas, and Beechcraft. 
  • Also, planes and custom airplane propellers must follow the same appropriate federal regulations during their flights.
  • Experimental aircraft are practically as safe as manufactured aircraft. Studies by the FAA and the National Transportation Safety Board (NTSB) show that experimental aircraft have an accident rate of less than 1% higher than the general aviation community.

Finding The Right People To Work On Your Custom Aircraft Propellers

There are very few surprises or breakthroughs when it comes to experimental aircraft design. 

Much like a relationship, every airplane build is a compromise: If you want a little more of this, you have to give up some of that. And vice versa. 

The freedom to fly something that doesn’t meet standard certification means that an airplane licensed in the experimental category will most likely fly differently than the norm. 

Its performance is optimized toward certain criteria that were important to the designer and builder. You’ll probably see sacrifices in other details to achieve that end.

Homebuilding is about freedom. The freedom to build what you want, use whatever materials you choose, and achieve whatever point you wish to make. Because homebuilders can create, modify, or change their aircraft as they want, there may be a chance for replication.

Then there’s always the freedom of expression. A homebuilt is like a blank canvas. The builder sketches out pretty much anything they want, putting their name on a design. They are free to do so, as long as it doesn’t endanger their life, passengers, or the populace below during flights.

At Stockton Propeller, we love the challenge of working with our experimental aircraft customers and working on their custom aircraft propellers. If you’re looking for someone in the Northern California/Nevada region to work on your homebuilt’s propellers, contact us today.

types of propellers

Types of Propellers : Fixed-Pitch, Ground-Adjustable, Reverse-Pitch, & Test Club

In our last blog post, we discussed Constant-Speed, Controllable-Pitch, and Feathering Propellers for aircraft. In this blog post, we want to finish covering some other types of aircraft propellers. Namely, we’re going to look at fixed-pitch, ground-adjustable, reverse-pitch, and test club propellers.

Stockton Propeller is a full-service governor, metal, and composite propeller shop in Stockton, California. If you need a composite propeller repair or overhaul, contact Stockton Propeller first.

Now, let’s look at some additional types of propellers – and their differences.

Fixed-Pitch Propellers

A fixed-pitch propeller has the angle, or pitch, built into the propeller, as the name implies. The pitch cannot be changed once  the propeller is completed. 

A fixed-pitch propeller is just one piece. Only one pitch setting is possible, and the whole configuration is usually a two-blade propeller. Once built, the pilot cannot change the angle of the propeller. Fixed-pitch propellers are generally made of aluminum alloy or wood.

Fixed-pitch propellers are a compromise of best take-off and climb performance and cruise. Many single-engine aircraft use fixed-pitch propellers. The advantages to these propellers are they are less expensive, and they are a simple operation. This type of propeller does not require any control inputs from the pilot in flight.

Fixed-pitch propellers are further categorized into two categories: metal propellers and wooden propellers.

Metal Propellers

In 1940, the military popularized the use of solid steel propellers. Very few of these still exist, but were very efficient for the time. 

Craftsmen create modern metal propellers from high-strength, heat-treated, aluminum alloy. The result was extremely successful and became the future of the propeller creation. 

Metal propellers are now used extensively for all types of aircraft. The metal propeller’s general appearance is similar to the wood propeller, but the sections are generally thinner. 

Additionally, metal propellers offer significant advantages to wood propellers. Aluminum alloy makes  these incredibly strong and durable propellers. Metal propellers today are heat treated to enhance their natural properties and make them less prone to warping from heat or cold. 

Today, it isn’t easy to find an airplane propeller made of anything but metal, for a good reason!

Wooden Propellers

Before World War II, personal and business aircraft almost exclusively used wooden propellers. 

It’s important to note that a wood propeller is not cut from a solid block. 

A wood propeller is several separate layers of carefully selected and prepared wood. The most common woods used in making these now-vintage wooden propellers were black walnut, sugar maple, yellow birch, and black cherry.

The use of lamination of wood will reduce the tendency for the propeller to warp. For standard one-piece wood propellers, five to nine separate laminations, about ¾-inch thick each, are used.

Because of the advancements in crafting metal propellers, wooden propellers are not common today. 

Ground-Adjustable Propeller

The function of ground-adjustable propellers is similar to that of fixed-pitch aircraft propellers. The pitch, or angle, can only be changed when the propeller is not rotating. 

A clamping mechanism holds the propeller blade in place. Loosening this mechanism allows the angle to be changed. 

After tightening the clamping mechanism, the propellers’ pitch cannot be changed in flight to meet varying flight requirements. With such limitations, present-day airplanes don’t commonly use the ground-adjustable propellers.

Reverse-Pitch Propellers

Additional refinements, such as reverse-pitch propellers (mainly used on turboprops), are included in some propellers to improve their operational characteristics. Almost all reverse-pitch propellers are of the feathering type. 

A reverse-pitch propeller is a controllable propeller in which the pilot can change the angle to a negative value during operation. The reversible pitch feature aims to produce a negative angle that has thrust opposite the normal forward direction. 

Typically, when the landing gear is in contact with the runway after landing, the pilot can move the propellers to a negative pitch (reversed), which creates thrust opposite the aircraft direction and slows the aircraft. As the propeller moves into a negative angle, engine power is applied to increase the negative thrust. 

The negative pitch aerodynamically brakes the plane and reduces ground roll after landing. Reversing the propellers also reduces aircraft speed quickly on the runway just after touchdown and minimizes aircraft brake wear.

A reversible pitch aims to create a negative angle to manufacture thrust in the opposite direction held previously. Propellers may be repositioned to a negative pitch after the plane has landed to come to a complete stop. 

Reversible pitch propellers are also used on floatplanes to allow the plane to be backed out of the docking area. 

Test Club Propeller

A test club propeller tests and breaks in reciprocating engines. They provide the correct amount of load on the engine during the test break-in period. 

The multi-blade design also has the advantage of providing extra cooling airflow during testing.

Even More Overwhelmed? Need Help With Your Aircraft Propeller?

No need to be overwhelmed at all of the different types of propellers and options for your aircraft! Contact the pros at Stockton Propeller for all your propeller repairs and overhauls. They are experts on servicing metal and composite propellers and are happy to assist you in meeting your needs!