As with other Soviet aircraft as they approached the
end of there useful life because of advances by the opposition, an attempt
was made to increase the performance by fitting ramjets to the under side
of the wings. In this case the Yak 7 was fitted with two Merkulov DM-4C
ramjets of 500mm diameter and a weight of 30 kg. The results were the
increased speed desired, but with very high fuel consumption as well as
high drag which slowed the plane down when the ramjets were turn off.
Tested twice first in 1942 on a Yak-7UTI, and again from March to December
1944 more successfully on a Yak-7B flown by S.N.Anokhin, how ever the
idea was dropped.
A side veiw of the same aircraft