Acro Sport Junior Ace: Classic Aerobatic Trainer

The Acro Sport Ace Junior Ace is a fascinating aircraft that holds a special place in aviation history, particularly within the home-built aircraft community. Designed by Orland Corben and later adapted by Paul Poberezny, the Junior Ace represents a blend of simplicity, functionality, and the spirit of aviation enthusiasts who take pride in building and flying their own planes. This article will delve into the rich history of the Junior Ace, its technical specifications, performance capabilities, and its enduring legacy in the world of sport aviation.

Part 1: The Origins and Development of the Junior Ace

The Ace Junior Ace was originally designed by Orland Corben in the early 1930s as a two-seat sports aircraft. Corben’s vision was to create an affordable, easy-to-build airplane that could be assembled by aviation enthusiasts at home. At the time, this concept was revolutionary. The idea of home-built aircraft was still in its infancy, but Corben’s design laid the groundwork for what would become a thriving subculture within the aviation community.

The Junior Ace was marketed by the Ace Aircraft Manufacturing Company, which Corben founded to promote his designs. The company offered plans and kits for homebuilders, allowing them to construct their own aircraft from scratch or from pre-fabricated parts. This democratization of aviation was a significant step forward for amateur pilots who wanted to experience the thrill of flying without the financial burden of purchasing a factory-built plane.

In its original form, the Junior Ace was adapted from Corben’s earlier design, the Corben Baby Ace, which was a single-seat aircraft. The Baby Ace had already gained popularity among homebuilders for its simplicity and ease of construction. However, recognizing the demand for a two-seat version that could accommodate both a pilot and a passenger, Corben modified the design to create the Junior Ace.

Paul Poberezny’s Influence

One of the most notable figures associated with the Junior Ace is Paul Poberezny, a legendary figure in sport aviation and the founding president of the Experimental Aircraft Association (EAA). Poberezny played a crucial role in promoting home-built aircraft and fostering a community of aviation enthusiasts through the EAA. He saw great potential in Corben’s designs and worked to refine and popularize them.

Poberezny’s involvement with the Junior Ace helped solidify its place in aviation history. His passion for experimental aircraft and his leadership within the EAA organization brought attention to homebuilding as a viable path for aspiring pilots. The EAA provided resources, support, and camaraderie for builders, helping to ensure that projects like the Junior Ace were successful.

Maiden Flight and Early Success

The first flight of the Junior Ace was piloted by Captain Bud Judy, who demonstrated its impressive capabilities during its maiden flight. The aircraft showcased several key features that made it well-suited for sport aviation:

• Short-field capabilities: The Junior Ace could operate from small airstrips thanks to its low stall speed and responsive handling.
• Low stall speed: This characteristic made it easier to land on shorter runways or less-than-ideal surfaces.
• Simple construction: The aircraft’s straightforward design made it accessible to amateur builders who might not have extensive experience with complex engineering.

The success of this maiden flight helped establish the Junior Ace as a reliable and practical choice for homebuilders looking for an affordable two-seat aircraft.

Part 2: Technical Specifications and Design Features

The Ace Junior Ace is known for its relatively simple yet effective design, which has remained largely unchanged since its inception. It is a monoplane with a parasol wing configuration—meaning that the wing is mounted above the fuselage on struts or pylons. This configuration offers several advantages, including improved visibility from the cockpit and enhanced stability during flight.

Airframe and Structure

• Fuselage: The fuselage is constructed from chromoly steel tubing, which provides strength while keeping weight to a minimum. The tubular structure is covered with fabric, which further reduces weight without compromising durability.
• Wing: The wooden wing has a wingspan of 7.92 meters (25.98 feet) and is supported by cabane struts or pylons attached to the fuselage. The wing spars and ribs are made from spruce wood—a lightweight yet strong material commonly used in aircraft construction.
• Landing Gear: The landing gear is conventional (taildragger), with chromoly steel tubes forming the main gear legs. Coil spring shocks are used to absorb impacts during landing, making it more responsive on rough or uneven surfaces.
• Tail Assembly: Like much of the rest of the airframe, the tail assembly is also constructed from chromoly steel tubing covered with fabric.

Cockpit Configuration

The Junior Ace has a tandem cockpit layout, meaning that one seat is positioned directly behind the other. This arrangement allows for better weight distribution during flight and provides both pilot and passenger with excellent visibility out of either side of the aircraft.

The cockpit can be either open or closed depending on preference—an option that adds versatility depending on weather conditions or personal taste. In many cases, builders choose to install an open cockpit for an authentic “wind-in-your-hair” flying experience reminiscent of early barnstorming days.

Engine Options

One of the defining features of home-built aircraft like the Junior Ace is their flexibility when it comes to engine choices. While many builders opt for engines from well-known manufacturers like Continental or Lycoming, there are several options available depending on budget or performance requirements.

• The most common engine used in modern versions of the Junior Ace is the Continental C85, which produces 85 horsepower.
• Other available engine options range from 85 hp up to 120 hp depending on builder preferences.

Performance Specifications

The performance characteristics of any aircraft are crucial when considering its suitability for various types of flying activities—whether it’s recreational flying or cross-country trips:

These performance figures make it clear that while not designed for high-speed travel or long-range flights, the Junior Ace excels at short-distance recreational flying where maneuverability and ease-of-use are more important than raw speed or altitude capabilities.

Weights & Dimensions

In terms of weight capacity:

• Maximum Takeoff Weight: 606 kg (1,336 lbs)
• Empty Weight: 367 kg (809 lbs)
• Maximum Payload: 170 kg (375 lbs)

These figures indicate that while relatively lightweight compared to modern factory-built aircraft, there’s still enough capacity for two occupants plus some additional baggage or cargo if necessary.

In terms of dimensions:

These compact dimensions make it easy to store in smaller hangars or garages when not in use—a key consideration for many amateur builders who may not have access to large storage facilities typically required by larger planes.

Citations:
[1] https://en.wikipedia.org/wiki/Ace_Junior_Ace
[2] https://aerocorner.com/aircraft/acro-sport-ace-junior-ace/

Part 2: Performance and Capabilities of the Junior Ace

The Ace Junior Ace is a versatile aircraft that offers impressive performance for its size and class. Although it was designed in the 1930s, its capabilities remain competitive within the realm of home-built sport aircraft. This section will explore the performance characteristics of the Junior Ace in detail, including its speed, range, fuel efficiency, and handling.

Engine and Powerplant Options

One of the defining features of the Junior Ace is its ability to accommodate a range of engines, allowing builders to tailor their aircraft to their specific needs. The most commonly used engine for this aircraft is the Continental C85, a reliable piston engine that produces 85 horsepower. However, builders can opt for engines with power outputs ranging from 85 hp to 120 hp depending on their performance requirements and budget.

• Common Engine Options:
• Continental C85: 85 horsepower (63 kW)
• Continental O-200: 100 horsepower (75 kW)
• Lycoming O-235: 115 horsepower (86 kW)

These engine options provide flexibility for builders who may want to prioritize fuel efficiency, power, or ease of maintenance. The Continental C85 is a popular choice due to its balance between power and fuel consumption, but those seeking more performance might opt for higher-powered engines like the Lycoming O-235.

Speed and Range

The Junior Ace is not designed for high-speed flight; rather, it excels in low-speed maneuverability and short-field performance. Its maximum speed is 113 knots (209 km/h), which is respectable for a two-seat sport aircraft built primarily for recreational flying.

• Maximum Speed: 113 knots (209 km/h)
• Cruise Speed: 91 knots (169 km/h)

The cruise speed of 91 knots makes it ideal for leisurely flights or short cross-country trips. The aircraft’s relatively low stall speed also contributes to its versatility in different flying conditions, particularly when operating from small or unimproved airstrips.

In terms of range, the Junior Ace can travel up to 217 nautical miles (402 kilometers) on a full tank of fuel. This range makes it suitable for regional flights or day trips without needing frequent refueling stops.

• Range: 217 nautical miles (402 km)

The combination of moderate speed and decent range ensures that the Junior Ace can cover significant distances without sacrificing comfort or safety.

Fuel Efficiency and Tank Capacity

Fuel efficiency is another important consideration for home-built aircraft like the Junior Ace. With a fuel tank capacity of 24 US gallons (91 liters), the aircraft strikes a balance between endurance and weight. The relatively small engine size—typically around 85 to 120 horsepower—ensures that fuel consumption remains manageable even during longer flights.

• Fuel Tank Capacity: 24 US gallons (91 liters)

For builders who prioritize fuel economy over raw performance, opting for an engine on the lower end of the power spectrum (such as the Continental C85) can result in more economical operation without sacrificing too much in terms of speed or range.

Service Ceiling and Rate of Climb

The service ceiling of an aircraft refers to the maximum altitude at which it can operate effectively. In the case of the Junior Ace, this ceiling is set at 10,500 feet, which is more than sufficient for most recreational flying scenarios. While it may not be suitable for high-altitude operations like mountain flying, it performs well at lower altitudes where most sport aviation takes place.

• Service Ceiling: 10,500 feet

The rate of climb—how quickly an aircraft can gain altitude—is another critical performance metric. The Junior Ace has a rate of climb of 600 feet per minute (3 meters per second), which allows it to reach cruising altitude relatively quickly without putting undue strain on the engine.

• Rate of Climb: 600 feet per minute (3 meters per second)

This rate of climb makes it easy to take off from shorter runways or grass strips, further enhancing its versatility as a sport aircraft.

Takeoff and Landing Distances

One of the standout features of the Junior Ace is its ability to operate from short airstrips. This characteristic makes it particularly appealing to pilots who may not have access to long paved runways or who enjoy flying into remote locations.

• Takeoff Distance: 107 meters (351 feet)
• Landing Distance: 137 meters (449 feet)

These short takeoff and landing distances are made possible by the aircraft’s low stall speed and lightweight construction. The conventional taildragger landing gear also contributes to its ability to handle rougher surfaces, making it suitable for grass strips or other unpaved runways.

Handling Characteristics

The handling characteristics of an aircraft are crucial for pilot confidence and safety. The Junior Ace is known for being relatively easy to fly, even for less experienced pilots. Its parasol wing configuration provides excellent visibility from the cockpit, while also contributing to stable flight characteristics.

The aircraft’s low stall speed—around 49 knots—makes it forgiving during landings and takeoffs. This low-speed handling capability is particularly beneficial when operating from shorter runways or in less-than-ideal weather conditions.

Weight Capacities

Weight is always a critical factor in aviation, especially when dealing with smaller home-built aircraft like the Junior Ace. The maximum takeoff weight (MTOW) for this aircraft is set at 606 kg (1,336 lbs), which includes both occupants, fuel, and any baggage or cargo being carried.

• Maximum Takeoff Weight (MTOW): 606 kg (1,336 lbs)
• Empty Weight: 367 kg (809 lbs)
• Maximum Payload: 170 kg (375 lbs)

With an empty weight of just under 370 kg, there is ample room for two occupants plus some additional baggage or equipment. However, builders must be mindful not to exceed the payload limit when planning flights with full fuel tanks or additional cargo.

Citations:
[1] https://en.wikipedia.org/wiki/Ace_Junior_Ace
[2] https://aerocorner.com/aircraft/acro-sport-ace-junior-ace/
[3] https://www.eaa.org/eaa/aircraft-building/kits-and-plans/00—c/corben-ace-and-junior-ace
[4] https://scauwg.org/aviation-events-calendar

Part 3: Construction and Design Philosophy of the Junior Ace

The Ace Junior Ace is a testament to the ingenuity and passion of aviation enthusiasts who prefer to build their own aircraft. One of the most appealing aspects of this plane is its straightforward construction process, which makes it accessible to amateur builders without requiring advanced engineering skills. In this section, we will explore the materials, design choices, and construction techniques that make the Junior Ace a popular choice among homebuilders.

Materials and Structural Design

The Junior Ace’s design is a combination of traditional materials and simple construction techniques that have stood the test of time. The primary materials used in its construction are chromoly steel tubing for the fuselage and wood for the wing structure. These materials were chosen for their strength-to-weight ratio, ease of use, and availability.

Fuselage Construction

• Chromoly Steel Tubing: The fuselage is built using chromoly steel tubing, which provides a lightweight yet strong framework. Chromoly steel is an alloy that includes chromium and molybdenum, making it both durable and resistant to corrosion. This material is commonly used in aircraft construction due to its high tensile strength and relatively low weight.
• Fabric Covering: Once the tubular frame is assembled, it is covered with fabric. The fabric covering not only reduces weight but also provides aerodynamic smoothness. Builders typically use modern synthetic fabrics such as Dacron or Ceconite, which are durable, lightweight, and easy to apply.

The fuselage design is relatively simple compared to more complex aircraft, which makes it easier for homebuilders to assemble. The use of fabric covering also allows for easier maintenance and repair compared to metal-skinned aircraft.

Wing Construction

The wing of the Junior Ace is constructed from wood, specifically spruce wood for the spars and ribs. Spruce has long been a favored material in aviation due to its excellent strength-to-weight ratio. The wing has a parasol configuration, meaning it is mounted above the fuselage on struts or pylons. This design provides several advantages:

• Improved Visibility: The parasol wing allows for better visibility from the cockpit compared to low-wing aircraft.
• Stable Flight Characteristics: The high-mounted wing contributes to stable flight characteristics, making the Junior Ace easier to control at low speeds.

The wing has a wingspan of 7.92 meters (25.98 feet), providing enough surface area for good lift while keeping the overall size manageable for storage in smaller hangars or garages.

Landing Gear

The Junior Ace features conventional landing gear—also known as a taildragger configuration—with two main wheels positioned forward of the center of gravity and a smaller tailwheel at the rear. This type of landing gear was common in early aircraft designs and remains popular among sport aircraft due to its simplicity.

• Chromoly Steel Tubing: Like the fuselage, the landing gear legs are made from chromoly steel tubing, providing strength without adding unnecessary weight.
• Coil Spring Shocks: The landing gear is equipped with coil spring shocks, which help absorb impacts during landings on rough or uneven surfaces. This feature enhances the aircraft’s ability to operate from grass strips or other unpaved runways.

The taildragger configuration requires some additional skill during takeoff and landing compared to tricycle gear (with a nosewheel), but many pilots enjoy the challenge and feel that it adds to the overall flying experience.

Tandem Cockpit Layout

One of the distinctive features of the Junior Ace is its tandem cockpit layout, where one seat is positioned directly behind the other. This arrangement has several benefits:

• Improved Weight Distribution: By placing both occupants along the centerline of the aircraft, weight distribution remains balanced even when flying solo.
• Enhanced Visibility: Both pilot and passenger have excellent visibility out of either side of the aircraft thanks to this seating arrangement.

The cockpit can be configured as either open or closed depending on personal preference. Many builders opt for an open cockpit design to capture the nostalgic feel of early aviation, but closed cockpits can be installed for those who prefer protection from wind and weather during flight.

Customization Options for Builders

One of the key attractions of building a home-built aircraft like the Junior Ace is the ability to customize various aspects of the plane according to personal preferences or specific performance goals. While some builders choose to follow Corben’s original plans closely, others take advantage of modern materials or technologies that were not available when the plane was first designed.

Engine Selection

As previously mentioned, builders have several engine options when constructing their Junior Ace. While many opt for tried-and-true engines like the Continental C85 or Lycoming O-235, others may choose alternative powerplants based on availability or desired performance characteristics.

For instance:

• Builders seeking better fuel efficiency might choose smaller engines with lower horsepower ratings.
• Those looking for more power might install larger engines capable of producing up to 120 horsepower.

This flexibility in engine choice allows each builder to tailor their aircraft’s performance based on their intended use—whether it’s leisurely weekend flights or longer cross-country trips.

Modern Avionics

Although originally designed with minimal instrumentation in mind—consistent with its role as a simple sport aircraft—modern builders often equip their Junior Aces with updated avionics systems. These systems can include:

• GPS navigation
• Digital flight instruments
• Radios for communication with air traffic control

While these modern avionics add convenience and safety features that were not available in earlier versions of the plane, they also increase complexity during construction and add weight to the final build.

Interior Finishing

Another area where builders can exercise creativity is in finishing the interior of their Junior Ace. Although many prefer a minimalist approach that keeps weight down (and stays true to Corben’s original vision), others may opt for more luxurious touches such as padded seats or custom upholstery.

Ease of Construction

One reason why so many aviation enthusiasts are drawn to building their own Junior Ace is because it’s relatively easy compared to other home-built aircraft projects. The plans provided by Corben (and later refined by Poberezny) are detailed enough that even those with limited experience can successfully complete their build with patience and attention to detail.

Some factors contributing to ease-of-construction include:

• Simple airframe design: The tubular steel frame requires basic welding skills but does not involve complex curves or difficult joints.
• Wooden wing structure: Working with wood is often less intimidating than working with metal components; many builders find it easier to shape spars and ribs using hand tools rather than specialized machinery.

Additionally, there are numerous resources available within organizations like EAA (Experimental Aircraft Association) where builders can seek advice from experienced members who have completed similar projects.

Part 4: The Legacy and Impact of the Junior Ace in Sport Aviation

The Ace Junior Ace has left an indelible mark on the world of sport aviation, particularly within the home-built aircraft community. Its simple design, coupled with its performance capabilities, has made it a favorite among aviation enthusiasts for decades. In this final section, we will explore the broader impact of the Junior Ace, its role in the home-building movement, and its continued relevance in modern aviation.

The Home-Built Aircraft Movement

The home-built aircraft movement has its roots in the early 20th century, but it truly gained momentum after World War II when surplus aircraft parts became widely available. During this time, many aspiring pilots and aviation enthusiasts sought affordable ways to take to the skies without purchasing expensive factory-built planes. The Ace Junior Ace, with its straightforward design and affordability, became one of the pioneering aircraft in this movement.

The Role of the Experimental Aircraft Association (EAA)

A significant factor in the success of the Junior Ace and similar home-built aircraft was the establishment of the Experimental Aircraft Association (EAA) in 1953 by Paul Poberezny. The EAA provided a forum for aviation enthusiasts to share ideas, resources, and support for building their own planes. Poberezny himself was deeply involved with the Junior Ace, recognizing its potential as a reliable and accessible aircraft for amateur builders.

The EAA’s annual event, EAA AirVenture Oshkosh, has since become one of the largest gatherings of aviation enthusiasts in the world. Many home-built aircraft, including numerous examples of the Junior Ace, are showcased at this event. The EAA also offers technical advice and resources to help builders navigate the complexities of constructing their own planes.

The Influence of Paul Poberezny

Paul Poberezny’s influence on sport aviation cannot be overstated. As both a pilot and an engineer, he saw great potential in home-built aircraft like the Junior Ace. His work with Corben’s designs helped refine them for a new generation of builders while maintaining their original simplicity and functionality.

Poberezny’s vision extended beyond just building airplanes; he wanted to create a community where aviation enthusiasts could come together to share their passion for flight. This vision was realized through the EAA, which continues to support builders around the world today.

Enduring Popularity Among Builders

Even though it was first designed in the 1930s, the Junior Ace remains popular among modern-day builders. Its enduring appeal can be attributed to several factors:

• Affordability: Compared to factory-built aircraft, building a Junior Ace is relatively inexpensive. The cost of materials is low, and builders can often find used engines or other components at reduced prices.
• Simplicity: The straightforward design makes it accessible even to those with limited experience in aircraft construction. Many first-time builders choose the Junior Ace as their initial project because it does not require advanced engineering skills or specialized tools.
• Customization: Builders have significant flexibility when it comes to customizing their Junior Ace. Whether it’s choosing an engine or upgrading avionics systems, each builder can tailor their aircraft to meet their specific needs.

For these reasons, many pilots who build a Junior Ace feel a deep sense of accomplishment when they complete their project and take to the skies in an airplane they built with their own hands.

Modern-Day Relevance

Despite being nearly a century old in design, the Junior Ace continues to be relevant today due to its adaptability and timeless appeal. In an era where many pilots are drawn to high-tech glass cockpits and advanced avionics systems, there is still a strong contingent of aviators who appreciate simplicity and hands-on flying.

Low-Cost Recreational Flying

One reason for its continued popularity is that it offers an affordable way to experience recreational flying. Many modern factory-built planes come with high price tags that put them out of reach for casual pilots. In contrast, building a Junior Ace allows pilots to enjoy flying without breaking the bank.

Additionally, operating costs are relatively low compared to larger or more complex aircraft. The small engines used in most Junior Aces are fuel-efficient, and maintenance costs are manageable due to the simplicity of the design.

Nostalgia and Classic Aviation

For many builders and pilots, flying a Junior Ace is about more than just getting from point A to point B—it’s about experiencing aviation as it was during its golden age. The open cockpit (in many configurations), parasol wing design, and taildragger landing gear evoke memories of barnstormers and early aviators who flew for the sheer joy of being in the air.

This connection to aviation history is one reason why so many pilots are drawn to classic designs like the Junior Ace. It offers an authentic flying experience that modern planes—despite their technological advancements—cannot replicate.

Notable Achievements and Pilots

Over the years, several notable pilots have flown or built their own versions of the Junior Ace. One such pilot was Captain Bud Judy, who piloted one of the first successful flights of this aircraft during its early development stages. His demonstration of its short-field capabilities helped establish its reputation as a versatile sport plane capable of operating from small airstrips.

In addition to individual achievements by pilots like Captain Judy, countless amateur builders have successfully completed their own versions of this iconic plane over decades—each contributing to its legacy within sport aviation.

Challenges Faced by Builders

While building a Junior Ace is generally considered easier than some other home-built projects, it is not without challenges:

• Time Commitment: Building any aircraft from scratch requires significant time investment—often hundreds or even thousands of hours depending on skill level.
• Technical Knowledge: While plans are detailed enough for most amateur builders to follow successfully, some technical knowledge (such as welding or woodworking) may be required.
• Regulatory Compliance: In most countries—including the United States—home-built aircraft must meet certain regulatory standards before they can be flown legally. Builders must ensure that their plane complies with local regulations regarding safety inspections and airworthiness certifications.

Despite these challenges, many builders find that completing their own airplane is one of life’s most rewarding experiences.

Future Prospects for Home-Built Aircraft

Looking ahead into future trends within sport aviation suggests that home-building will continue playing an important role—especially as technology advances make components more accessible than ever before:

• Advances in materials science (such as carbon fiber composites) could lead future builders towards lighter yet stronger airframes.
• New engine technologies—such as electric propulsion systems—may offer alternative powerplants better suited towards environmentally-conscious aviators looking reduce emissions while still enjoying recreational flying.

However futuristic developments may unfold though—it seems certain that classic designs like Corben’s original Baby & Junior Aces will always hold special place hearts those passionate about DIY approach personal flight!

Conclusion: A Timeless Classic in Aviation History

The Ace Junior Ace represents more than just an airplane—it symbolizes freedom creativity inherent within spirit flight itself! From humble beginnings back 1930s right up present day—it continues inspire generations aviators around globe who dream building piloting machines soar skyward under own power ingenuity determination alone!

With blend simplicity elegance combined rugged performance capabilities—it remains beloved choice anyone seeking taste old-school adventure coupled modern-day practicality affordability unmatched anywhere else world sport aviation today!