A quick query - is the propellor shaft on the T-4 'Booklet' at an angle? It's just that, looking at it, the prop seems at an angle, so unless it's mounted swashplate-like on the shaft (and I don't think that's good for the prop?) or I'm looking at it wrong something's a little amiss...
It is not, it's an allusion created by the blade angles.
BTW all of these are based either on real Russian or (mostly) Chinese concepts.