These days unfortunately, I feel that the conventional helicopter has been, or is rapidly being replaced by the drone. The "dragon ship" is a prime example.

One would think that once there was enough altitude & forward momentum, the vertical takeoff rotors would somehow retract or "fold up" into something more aerodynamic. Alternatively, the main rotors may booster both velocity & altitude albeit with much more powerful engines than the smaller rotors which only propel the craft forwards.

What a huge might have been helicopter. I am not sure that such a unit could flight correctly. But I wish I could find a 1 /72 model kit Who said ?

they provide vertical takeoff

World most beautiful & powerful workhorse.
Now do you have an agent in Malaysia.

Brautiful

The Ulitimate Blinder

Judging from the model, what theoretical speed could be obtained in foward flight?

To morko:

Not really! they would provide lift during autorotation! Heavier load for a smaller and stiffer wing. U.S. Cartercopter is a similar concept design!

General comment:
Rather cancelled due to complexity. Soviet Union realy focused in simple designs suitable for mass production.

Wonder if they ever built any of these and whether (Or) Not they actually had "Flying!" examples?

Yeah I don't know how well this would fly but it sure looks cool

wouldn't that huge vertical rotors only provide drags in cruising flight ?