Type B IV 2-seated sportplane developed from B II B IVa 2-seated sportplane developed for record attempts
Engine 1 Wright L4
Dimensions Length 6.25 m, span 9.15 m,  wing area 11.20 m2,  aspect ratio 7.5 Length 6,25 m m , height  ,  span 9,00 m m , wing area  11,00  m2, aspect ratio 7,25 ,
Weights Empty 300 kg, fuel 106 kg, oil 4 kg, crew 150 kg, luggage 15 kg, load 275 kg, flying weight 575 kg, wing loading 51.43 kg/m2 Empty  295 kg, fuel 106 kg, oil 4 4 kg, crew 150 kg, luggage 45 kg, load 305 kg, flying weight 600 kg, wing loading 54 kg/m2
Performance Max. speed 211 km/h, cruising speed 180 km/h, climb to 1000 m 6 min., , ., service ceiling 6780 m, range 1000 km, landing speed 85 km/h Max. speed 215 km/h, cruising speed 180 km/h,    service ceiling 7000 m,climb to 1000 m 4,5  min range 1200 km, max. range 2000 km, landing speed 80 km/h
Type Werk.Nr Registration History
B IV Sausewind II 104 ? D-885 Bäumer Aero GmbH. Total damage 30.3 1927 at Berlin
B IV Sausewind III 105 D.1158 Bäumer Aero GmbH. To DVL Adlershof in October 1927. Dismantled in October 1936, transferred to the "Deutsche Luftfahrt-Sammlung"
B IVa Sausewind IV
 106 D-1414 Bäumer Aero GmbH. In March to Luftverkehr Gesellschaft  Hamburg, To E. Petersen Hamburg in April 1930. To Hubertus Graf Reventlow-Criminil Hamburg. Total loss 14.5 1931 at Travemünde
In 1925, Paul Bäumer, after analyzing the success of the B.II and the failure of the B.III, decided to continue work on improving the Sausewind. The main areas of modernization were to increase the comfort of the crew, ease of control (decrease the sensitivity of the rudders), increase the flight speed and reduce the landing speed.

As a result, in 1926 by Baumer Aero GmbH. a light sport aircraft Bäumer B.IV Sausewind (W.Nr. 104) was built. The main differences of the new aircraft were the dual-control cockpit and the new wing profile. Thanks to innovations during testing, it was possible to reach a maximum speed of 210 km / h, which made the B.IV the fastest aircraft built in Germany at that time. And the low control sensitivity and lowering the landing speed to 85 km / h made it possible to control the machine even for not very experienced pilots.

A total of two copies of the B.IV were built, which received registration numbers D-885 and D-1158 (W.Nr.105). The first crashed in March 1927, and the second was made in the summer of the same year. This instance set several world records at once.

On July 8, 1927, the B.IV broke the world altitude record for aircraft of this class - 6782 meters. And two days later, the speed record for the class of "light two-seat aircraft" was broken - a distance of 100 kilometers was overcome at an average speed of 191.2 km / h.

July 15, 1927 Paul Bäumer crashed while performing a demonstration flight of the Ro.IX Rofix fighter. The brothers Gunther, Walter and Siegfried (Walter, Siegfried Günter) took up the further development of the project.

In September 1927, another copy of the B.IVa (W.Nr.106, D-1414) was completed with smaller wingspan. On October 4, 1928, another world record was broken on it (speed record in class "C" of the 1st category (double) - 214.5 km / h. However, for unknown reasons, the FAI did not recognize it.

In March 1929, the aircraft was acquired by the Hamburg GmbH airline. Already on behalf of this company, B.IVa was put up to participate in the "Challenge International d'Avions de Tourisme 1929" competition. After the bankruptcy of the company, the aircraft changed several private owners until it crashed in May 1931 and was never restored.