In late 60's, there was a strong need for a second generation AEW aircraft in the Soviet Union.
Tupolev examined the following options:
Tu-142M, the PVO prefered choice, but the narrow fuselage offered little space.
Tu-126, the best choice for Tupolev, but all the jigs had been thrown away
Tu-154 configuration and endurance proved unsuitable for the role
Analysis indicated that an all-new design would be best and subsequently, the Tu-156 crystalliced.
On 7th August 1969 Il'yushin received a ruling requiring to undertake preliminary development of an AWACS based on the Il-76 project. It was designated Il-70
The Tu-156 proved unacceptable to the Soviet Air Force, which insisted that an aircraft in production should be used. Eventually, they opted for the Il-76 as the basis for the new AWACS.
The Il-76 first flight took place on 25th March 1971.
Il'yushin teamed with with Beriev and the resulting Aircraft was designated A-50.
Tu-156 Project Data:
Length: 52.2 m
Wing Span: 45.8 m
Max TOW: 182.000 Kg
Service range, on internal fuel: 5200 Km
Powerplant: Solov'yov D-30KP turbofan 12000 Kgp
I have no drawings on the type. Just the pics from the model you already know
Saludos
Source:
http://www.amazon.com/s/ref=nb_ss_gw/104-7373509-8501568?url=search-alias%3Dstripbooks&field-keywords=soviet%2Frussian+awacs+aircraft&Go.x=16&Go.y=9&Go=Go