Messerschmitt M 23
Type
a   Two seat sportplane
a   Two seat sportplane
b Two seat sportplane
b   Two seat sportplane
b  Two seat sportplane
Engine
1 ABC Scorpion II
1 Salmson AD 9
1 Sh 13
1 Armstrong-Siddeley
Genet 1
1 ADC Cirrus III
Dimensions
Length 6.65 m, height 2.30
m, span 11.80 m, wingarea
14.40 m2
Length 6.65 m, height
2.30 m, span 11.80 m,
wingarea 14.40 m2
Length 6.50 m, height
2.30 m, span 11.80 m,
wingarea 14.40 m2
Length 6.66 m, height 2.30
m, span 11.80 m, wingarea
14.40 m2
Length 6.43 m, height 2.30
m, span 11.80 m,
wingarea 14.40 m2
Weights
Empty 220 kg, fuel 70 kg,
load 220 kg, flying weight
440 kg
Empty 250 kg, fuel 70 kg,
load 230 kg, flying weight
480 kg
Empty 325 kg, fuel 70 kg,
load 270 kg, flying weight
595 kg
Empty 285 kg, fuel 70 kg,
load 250 kg, flying weight
535 kg
Empty 355 kg, fuel 70 kg,
load 245 kg, flying weight
600 kg
Performance
Max. speed 130 km/h, climb
to 1000 m 13 min., service
ceiling 3300 m, range 920
km, landing speed 60 km/h
Max. speed 140 km/h,
climb to 1000 m 10.5
min., service ceiling 3700
m, range 810 km, landing
speed 62 km/h
Max. speed 162 km/h,
climb to 1000 m 5.5 min.,
service ceiling 4800 m,
range 800 km, landing
speed 66 km/h
Max. speed 165 km/h,
climb to 1000 m 5.7 min.,
service ceiling 5600 m,
range 800 km, landing
speed 65 km/h
Max. speed 180 km/h,
climb to 1000 m 5.0 min.,
service ceiling 5300 m,
range 700 km, landing
speed 68 km/h
Type
b   Two seat sportplane
b  Two seat sportplane
b  Two seat sportplane
c  Two seat sportplane
c  Two seat sportplane 
Engine
1 ADC Cirrus  Hermes
1 Sh 14
1 BMW X
1 Argus As 8
1 Sh 14a
Dimensions
Length 6.43 m, height 2.30
m, span 11.80 m, wingarea
14.40 m2
Length 6.35 m, height
2.30 m, span 11.80 m,
wingarea 14.40 m2
Length 6.50 m, height
2.30 m, span 11.80 m,
wingarea 14.40 m2
Length 7.00 m, height 2.40
m, span 12.00 m, wingarea
14.40 m2
Length 7.00 m, height 2.40
m, span 12.00 m,
wingarea 14.40 m2
Weights
Empty 360 kg, fuel 70 kg,
load 240 kg, flying weight
600 kg
Empty 370 kg, fuel 70 kg,
load 300 kg, flying weight
670 kg
Empty 308 kg, fuel 70 kg,
load 292 kg, flying weight
600 kg
Empty 320 kg, fuel 70 kg,
load 280 kg, flying weight
600 kg
Empty 400 kg, fuel 70 kg,
load 200 kg, flying weight
600 kg 
Performance
Max. speed 185 km/h, climb
to 1000 m 4.5 min., service
ceiling 6000 m, range 700
km, landing speed 68 km/h
Max. speed 185 km/h,
climb to 1000 m 5.0 min.,
service ceiling 5200 m,
range 1000 km, landing
speed 70 km/h
Max. speed 140 km/h, 
Max. speed 175 km/h,
climb to 1000 m 4 min.,
service ceiling 6150 m,
range 750 km,
Max. speed 220 km/h,
cruising speed 185 km/h
climb to 1000 m 2.2 min.,
service ceiling 6500 m
The BFW M.23,[1] the M standing for its designer Willy Messerschmitt, was developed in response to a specification issued in 1929 by the German Aero Club for the Ostpreussenflug (East Prussian Circuit) competition. The result was an improved version of the M.19, with seating for two, and wings that could be folded for transport or storage.
The M.23 was a small conventional low-wing cantilever monoplane. It had a fixed undercarriage, the main-wheels mounted on a cranked axle plus a tailskid. The fin and rudder assembly was broader and shorter than that of the M.19, though the shape varied with sub-type. A wide variety of engines were fitted, powers ranging from the 28 kW (38 hp) ABC Scorpion two-cylinder motor to the 112 kW (150 hp) of the seven-cylinder Siemens Sh 14a radial.
The first of three production variants, the M.23a used low-powered engines and had a very angular vertical tail. The M.23b had curved upper fuselage decking and a more rounded tail and was produced with a large range of engines, both inline and radial. The length depended slightly on the engine fitted. The final version, the M.23c had an enclosed cockpit, the most powerful engines and was slightly larger (200 mm/8 in in span, around 500 mm/20 in in length) than the earlier varieties. Its tail was again different, more rounded at the top and missing the elevator cut-away of the earlier models. At least one M.23b appeared on floats.
M.23bs won both the 1929 Ostpreussenflug (Genet-powered) and the Circuit of Europe (Siemens Sh 13-powered) races. The M.23c was developed for, and won, the Circuit of Europe the following year with seven of them entered.
Production numbers are not certain, but 74 appear on the reconstructed German civil aircraft register;53 of these are M.23bs and 11 M.23cs. Many were bought by flying clubs for basic and acrobatic training. Other went to individual owners, with some familiar names amongst them like Ernst Udet (who made well publicised flights to Africa and to Greenland, the latter with Leni Riefenstahl as a passenger) and Rudolph Hess. In 1933, Erwin Aichele and his wife flew trouble-free for 13,000 km (8,000 mi) around the Mediterranean.
The corresponding Romanian registers show 26 more M.23bs, 14 of them locally built by ICAR (Intreprinderea de Constructii Aeronautice Romanesti, "Enterprise for Romanian Aeronautical Constructions") under licence from Messerschmitt. These were distinct from the Romanian modified version known as the ICAR Universal. The licensing deal was part of Messerschmitt's successful attempt to save a small core of staff from BFW when it went bankrupt in June 1931, a group that became Messerschmitt-Flugzeubau GmbH and survived until the reformation of BFW under the Nazis in 1933.