(Sometimes Merkoulov or Mercoulov).

Merkulov was a Soviet designer of ramjet and pulsejet engines.

-With the initials DM, Dopolnityelnyi Motor (Supplementary Motor) were a series of motors designed by I.A. Merkulov (Mercoulov sometimes).

-Ramjets like the DM-1 had a diameter of 200 mm, and were tested in 1939. It consumed the same fuel as the piston engine, gasoline.

“DM-2 on I-153”

-Despite the drag or resistance to advance when the ramjet was not running and its own weight, it exceeded the obtained advantages.

-There was installed one below each lower wing.

-The DM-4 engines, ​​or next model that came out, were ramjets.

-We see it in a test tunnel for the Bereznyak-Isaev BI-6 aircraft.

"BI-6 with simulated DM-4 engines"

-The BI-6 normally carried a rocket main engine of Dushkin-Isaev's model D1A-1100 design in addition to the two DM-4s at the wing tips.

-The DM-4, ​​more operational than the previous ones, measured 500 mm in diameter and in 1940 it was tested on a Polikarpov.

“DM-4 on Polikarpov”

-The DM-4 weighed about 30 Kgs. And the engine required ethyl-glycol antifreeze in addition to the gasoline.

“DM-4 on Borovkov-Florov”

-The DM-4C was an improved version of the DM-4 and was tested on the Yak-7B and -7R. With these engines, the total speed of the plane was increased to 318 miles per hour.

“DM-4C on Yak-7B”

-They continued to make variants like the RD-45 that was also tested on the Yak-7 in 1944.

“DM-4 on Yak-7B”

-The Merkulov pulse jets were tested on the Lavochkin La-7, which, like the one in the photo, carried the RD-13s. The aircraft was renamed as La-7PVRD.

“La-7 with pulsejets”

-The Lavochkin La-126 was an upgraded version of the La-7 and also flew with pulse jets, this time the VRD-430.

“La-126 with VDR-430 pulsejets”

“La-9RD with RD-13 pulsejets”

-Lavochkin's La-9 was also altered with the RD-13 pulse jet assembly.

-Another upgraded version of the La-9 was the Lavochkin La-138 that was fitted with the VRD-430s.

“La-138”

-The pulsejets added to all these planes used to give a speed increase of about 40 miles per hour. But the high fuel consumption meant that it only took a few minutes.

-These penalties are added to those mentioned above, resulting in some little operational planes.

-However, these experiences had to be done to continue progressing. (see Bondariuk).

From Appendix 9: Ramjet and pulsejet engines were used experimentally in WWII and shortly thereafter to increase the performance of interceptor fighters, which in this case did not compensate for the increase in thrust with weight and consumption.

-We have received two pictures of engines that are mentioned in the main text, the DM-2 engine. One installed on the Polikarpov I-153 and the other on a monoplane fighter.

"Side view of the Merkulov on an I-153"

"Another view of a DM-2"