Henry Mignet HM 300

Mignet HM.300: The Evolution of a Genius Idea

If the HM.14 was the revolutionary spark, the Mignet HM.300 (and its close variants like the 310 and 320) represents the maturity of that idea. Designed by Henri Mignet after World War II, this aircraft is the result of decades of experience. Mignet took his original concept of absolute safety and refined it, creating a machine that was not only incredibly safe but also sleeker, more aerodynamic, and more practical for the amateur builder of the new era. It is the Flying Flea that grew up and was perfected.

Why Is It So Special?

• The Same Safety, Perfected: The heart of the HM.300 is still the stall-proof, spin-proof Mignet system. It retains the tandem wings and the pivoting front wing, ensuring the aircraft self-corrects in low-speed situations, but now with more refined airfoils and overall aerodynamics.

• A More Aerodynamic Approach: Unlike the “box-like” fuselages of the early models, the HM.300 introduces a more rounded, flowing construction. Typically built with a wood frame and fabric covering, its shape reduces drag, which directly translates to more speed and efficiency on the same power.

• Optimized for More Capable Engines: This design was conceived to take advantage of the more reliable and powerful post-war engines that were becoming available. It is the perfect airframe for the legendary air-cooled Volkswagen engine (typically 1200cc), offering an ideal combination of reliability, low cost, and adequate performance.

• The Builder’s Sweet Spot: The HM.300 strikes a perfect balance. It maintains the constructional simplicity of the original (wood, fabric, no complex welding), but the end result is a more “professional” looking aircraft with more useful performance for local flights and short cross-country trips.

Performance and Key Numbers

The HM.300’s figures show a clear improvement over its predecessors, offering more versatility without sacrificing safety.

General Specifications (Typical):

• Crew: 1 pilot

• Front Wingspan: Approx. 19.7 ft (6 m)

• Length: Approx. 13.8 ft (4.2 m)

• Total Wing Area: 130 sq ft (12 m²)

• Empty Weight: 400 – 485 lbs (180 – 220 kg)

• Max Takeoff Weight: 705 – 770 lbs (320 – 350 kg)

• Typical Powerplant: Air-cooled Volkswagen 1200cc (30-40 hp)

Performance:

• Maximum Speed: 87 mph (140 km/h)

• Cruise Speed: 65 – 72 mph (105 – 115 km/h)

• Minimum Flying Speed (No stall): 34 mph (55 km/h)

• Rate of Climb: 600 – 700 ft/min (3 – 3.5 m/s)

• Takeoff Distance: 330 – 400 ft (100 – 120 m)

• Landing Distance: 260 ft (80 m)

• Range: Approx. 185 – 220 miles (300 – 350 km)

In summary, the Mignet HM.300 is the refined and optimized version of a revolution. It is the ideal choice for the builder who loves the Mignet safety philosophy but desires an aircraft with a more classic look and slightly superior performance to enjoy aviation with complete peace of mind.