The Walter Regulus was a Czechoslovakian five-cylinder, aircooled, radial engine for powering light aircraft that first ran in 1934. The engine produced 186 kW (250 hp).

Regulus
Type: 5-cylinder radial piston engine
Valvetrain: One intake and one exhaust valve per cylinder
Fuel system: Carburettor
Fuel type: Petrol
Cooling system: Air-cooled
Power output: 186 kW (250 hp)

The Walter Polaris was a Czechoslovakian three-cylinder, aircooled, radial engine for powering light aircraft that was developed in the 1930s.

Applications:
Letov Š-39

Specifications
Polaris
Type: 3-cylinder radial piston engine
Valvetrain: One intake and one exhaust valve per cylinder
Fuel system: Carburettor
Fuel type: Petrol
Cooling system: Air-cooled

The Walter Vega was a five-cylinder, air-cooled, radial engine for aircraft first run in 1929.

Applications:
Aero A.34
ANBO V
Avia BH-11

Specifications:
Type: 5-cylinder radial engine
Bore: 105 mm (4.1 in)
Stroke: 120 mm (4.7 in)
Dry weight: 102.5 kg (226 lb)
Valvetrain: Overhead valve, one inlet and one exhaust valve per cylinder
Fuel system: Zenith Type 50J carburettor
Fuel type: Petrol
Oil system: Pressure and scavenge pump
Cooling system: Air-cooled
Reduction gear: Direct-drive
Power output: 63 kW (85 hp) at 1,750 rpm
Compression ratio: 5.15:1
Power-to-weight ratio: 0.61 kW/kg (0.37 hp/lb)

The Walter Pollux was a Czechoslovakian nine-cylinder, aircooled, radial engine for powering light aircraft that first ran in 1936. The engine produced 335 kW (450 hp) at 1,800 rpm.

The first known use was on the Fieseler F 2 Tiger in 1934.

Variants:
Pollux II
Direct drive engine

Pollux II-R
Geared engine, reduction ratio 0.666:1

Applications:
Aero A.204
Avia B.122
Fieseler F2 Tiger
Praga BH-41

Specifications:
Pollux IIR
Type: 9-cylinder radial piston engine
Bore: 135 mm (5.3 in)
Stroke: 170 mm (6.7 in)
Dry weight: 340.6 kg (751 lb)
Valvetrain: One intake and one exhaust valve per cylinder
Fuel system: Carburettor
Fuel type: Petrol
Cooling system: Air-cooled
Power output: 358 kW (480 hp) at 2,070 rpm
Compression ratio: 6:1
Power-to-weight ratio: 1 kW/kg (0.64 hp/lb)

The Walter NZ 120 was a nine-cylinder, air-cooled, radial engine for aircraft use built in Czechoslovakia by Walter Aircraft Engines in the 1920s. Using common cylinders and parts from the NZ (Novák-Zeithammer) range of engines the NZ 120 produced up to 135 horsepower (99 kW).

Applications:
Avia B.122
Breda Ba.26
Fizir FN
Junkers K 16
Letov Š-218
Praga BH-39NZ
RWD 8

Specifications:
Type: Nine-cylinder radial piston engine
Bore: 105 mm (4.1 in)
Stroke: 120 mm (4.7 in)
Displacement: 9.36 L (571.2 cu in)
Dry weight: 148 kg (326 lb)
Valvetrain: Overhead valve, two poppet valves per cylinder
Cooling system: Air-cooled
Reduction gear: Direct drive
Power output: 99.3 kW (135 hp) at 1,750 rpm (take-off power)
Compression ratio: 4.48:1

The Walter Mikron is a four-cylinder, aircooled, inverted straight engine for aircraft, produced in Czechoslovakia. Since 1999, the engine was again being produced by Parma Technik of Luhačovice, mostly used on ultralight and LSA aircraft.

Variants:
Mikron I
Initial production engines producing 37 kW (50 hp).

Mikron II
The Mikron II, released in 1936, had a bore of 88 mm (3.46 in) and displacement of 2.336 l (142.55 cu in), delivering 45 kW (60 hp) at 2,600 rpm max continuous and 46 kW (62 hp) at 2,800 rpm for short periods. After a hiatus in production during the Second World War, production resumed till 1948, when the Micron III went into production.

Mikron III
With a displacement of 2.44 l (148.90 cu in), it produces 48.5 kW (65.0 hp) at 2,600 rpm.

Mikron IIIA

Mikron M IIIAE

Mikron IIIB
New improved version of the Mikron 56 kW (75 hp) at 2,750rpm for 5 minutes, max continuous power of 51 kW (69 hp) from 2.44 l (148.90 cu in), bore 90 mm (3.54 in), stroke 96 mm (3.78 in), dry weight 69 kg (152.12 lb)

Mikron IIIC
60 kW (80 hp) at 2,800rpm from 2.7 l (164.76 cu in), bore 93.3 mm (3.67 in), stroke 96 mm (3.78 in).

Aster 4A
Licenced Walter Mikron, 60 hp

Applications:
Aerolab LoCamp
Avia BH-1
Alaparma Baldo
Avions Fairey Belfair
Avions Fairey Junior
Bücker Bü 180
Chrislea Airguard
Currie Wot
Isaacs Fury
Jodel D11
Johansen CAJO 59
Koolhoven F.K.53
L-13 SE Vivat
L-13 SW Vivat
Lemberger LD20b
Luton Major
LWD Żak
Podesva Trener
RWD-16
RWD-21
RWD-23
Rogožarski SIM-VI
Rogožarski SIM-VIa
Skandinaviska Aero BHT-1 Beauty
Tipsy B
Utva Trojka
Zlín Z-XII

Specifications:
Mikron II
Type: 4-cylinder inverted air-cooled inline
Bore: 88 mm (3.46 in)
Stroke: 96 mm (3.78 in)
Displacement: 2.336 l (142.6 cu in)
Length: 804 mm (31.65 in) with starter
Width: 342 mm (13.46 in) with fuel pump
Height: 635 mm (25.00 in) with fuel pump
Dry weight: 61 kg (134.48 lb) dry
Valvetrain: One intake and one exhaust valve per cylinder operated by pushrods and rockers
Fuel system: 1 Claudel-Hobson carburettor
Fuel type: 73 octane gasoline
Oil system: Pressure fed, dry sump
Cooling system: Air-cooled
Starter: 1x Walter mecano 4 hand starter
Power output: 45 kW (60 hp) at 2,600 rpm continuous, 46 kW (62 hp) at 2,800 rpm maximum for short periods
Compression ratio: 6:1
Power-to-weight ratio: 0.8 kW/kg (0.5 hp/lb)

The Walter Mars was a Czechoslovakian 14-cylinder, aircooled, radial engine for powering aircraft that was developed in the 1930s.

Applications:
Breda Ba.15
DAR 4
DAR 6
Fizir FN
Focke-Wulf A 33
Letov Š-32
Messerschmitt M 18

Specifications
Type: 14-cylinder radial piston engine
Valvetrain: One intake and one exhaust valve per cylinder
Fuel system: Carburettor
Fuel type: Petrol
Cooling system: Air-cooled

Walter Major was a family of Czechoslovak aircraft inline engines developed by Walter Aircraft Engines in the 1930s. First run in 1934, it was available in either four or six cylinder configuration, with identical bore and stroke of 118 mm (4.6 in) and 140 mm (5.5 in), respectively, the Walter Majors were primarily used in light aircraft. License-built in Poland by the state-owned Państwowe Zakłady Inżynieryjne (as the PZInż. Major 4), the engine was used in, among others, Zlin Z-XIII, RWD-11 and one of the PWS-35 Ogar prototypes.

Applications:
Beneš-Mráz Be-50 Beta-Minor
Beneš-Mráz Be-52
Beneš-Mráz Be-56
Beneš-Mráz Be-250
Beneš-Mráz Be-251
González Gil-Pazó GP-4
PWS-35 Ogar
Rogožarski SIM-XII-H
RWD-11
RWD 20
Spartan Cruiser
Zlin Z-XIII

Specifications:
Major-4
Type: 4-cylinder inverted inline engine
Bore: 118 mm
Stroke: 140 mm
Dry weight: 140 kg
Cooling system: Air-cooled
Power output: 130 hp
Compression ratio: 5.2:1

First run c.1934, the Walter Gemma was a Czechoslovakian nine-cylinder, air-cooled, radial aero engine that was developed and manufactured in the early 1930s by Walter Aircraft Engines.

Applications:
Nuri Demirağ Nu D.36
Praga E-39

Specifications:
Type: 9-cylinder radial piston engine
Displacement: 9.35 L (570.6 cu in)
Valvetrain: One intake and one exhaust valve per cylinder
Fuel system: Zenith carburettor
Fuel type: Petrol
Cooling system: Air-cooled
Power output: 165 hp (123 kW)