In 2016 it was not tested on a sub (that was planned only for 2017). DRDO also lists it only for ASW ships. But other articles talk about developmentof a sub launched version and of orders for launching against sub and shipsAnujan wrote:There were articles hinting that varunastra was only for ships and not subs
So the status of the sub launched version has conflicting reports. And the lack of the capability in 2016 may explain the 2016 report.
However, SUT is from the U-209 stock. And it is a heavyweight torp for both surface and underwater target (and can be fired from land, ship and sub).
Similarly Blacksharkis for all threats (surface/underwater) from land,ship and sub and has wire, acoustic and wake follow guidance modes. and swim out and push out modes. This is the one India wanted for Scorpene but was banned.
Because only ASW (anti submarine) was mentioned for Varunastra and because numbers didn't seem enough for 6 Scorpenes and ships, I implicitly assumed that there would be other heavyweight torpedos also to be bought for use from subs. Possibly with some of those advanced modes.
Now I'm wondering about the sub launched varunastra status and utility of a sub torpedo that is only ASW.
In any case Atlas Electronik will likely offer a version of itsDM2/Sehaketorpedo which has all swim out etc modes, wake homing, etc guidance and fibre optic wire .
While the French Naval group F21torpedo also has all these. Of course, there will be differences including propulsion chemistry, ECCM etc.