As a matter of fact, NATO was very poorly informed about Soviet nuclear air power potential during the mid-1960s.
Construction at five bases in the GDR, Poland and Hungary was noticed almost right away and thoroughly
documented, yet it is not known exactly what was stored there. Once-secret documents from the CIA and USMLM (the
United States Military Liaison Mission in East Germany - see > links) which have since been
de-classified could be of some help here. A US intelligence paper ("Capabilities of Soviet General Purpose Forces")
from December 1964 about Soviet military capabilities contained a surprising summary: "We have only discovered nuclear
weapons in the USSR so far.
If the Soviets did not store such weapons in Eastern Europe (its western part), then
it would be a great logistical and time consuming effort for them."
The designation IAB-500 (Imitatsionnaya Aviatsionaya Bomba - simulation aviation bomb)
also informs us of the weapon's size and specifications. That bomb used the same aerodynamical body as the 8U46/8U47/8U49 tactical
nuclear bombs. The IAB-500 served not only to instruct the loading, transport and guard personnel for
such weapons, but was actually a conventional weapon itself. The contents consisted of a highly explosive mixture
of 150kg of kerosene, 58kg of white phosphorus and 34kg of explosives (TNT and TGA 11).
The explosives that detonated above the target (1)
broke the body of the bomb and freed the phosphorus which, in turn, inflamed the kerosene.
The explosion provoked a fireball followed by a rapidly growing and billowing mushroom cloud (the phosphorus coloured the cloud white for added realism) -
all the tell-tale signs of a nuclear explosion. Witnesses reported clouds of up to 200 meters!
"The two situations differed however in that the August
'67 release resulted in an air detonation of the weapon producing a large grey-black mushroom-shaped cloud, while the
release observed this date resulted in a normal ground burst.' Similar observations were also made with units
based in the south of the GDR, the 559.IBAP at Finsterwalde and the 497.IBAP at Grossenhain. That proved the nuclear
capability of all units equipped with Su-7 "Fitter-A": "On 7 October Finsterwalde-based "Fitter" performed a minimum
of four LABS delivery practice runs. The aircraft passed over the airfield at approximately 2,000ft, pulled up into
vertical climb to 3,500ft, pitched over, flew inverted for several seconds, then rolled over again departing to the
west. A very active program of local navigational, touch-and-go landings, LABS maneuvers, and possible range activity
was flown by Grossenhain-based "Fitter" and "Moujik" on 9 October."
Low-Altitude Bombing System
In order to be able to deliver a weapon with precision during a toss bombing or LABS manoeuvre, the original
weapon system of the aircraft had to be supplemented by an additional switchbox and indicator. The latter was called
PBK (Pritsel dliya Bombometaniya s Kabrirovaniya or toss-bombing sight). On early jets like the Su-7,
the PBK was a separate box which was added to the left side of the instrument panel.
A fixed point had to be selected
on the ground to start the bombing run. That fixed point could be identified visually or it could be a radio beacon put in
place by a commando unit or an helicopter. The PBK box gave to the pilot the informations necessary to complete its final bombing run
(see > Hawk strike). HM.
This chapter is an adaptation of the article entitled 'Nuclear Power' by Stefan Büttner, published in the March 2009
issue of Aircraft Illustrated (Ian Allan Publishing).
notes
(1)
Like the tactical nuclear bombs, the IAB-500 was equipped with a remote or a direct impact fuse that determined the moment of detonation in order to create an aerial or a ground burst.
Tactical nuclear bombs could be dropped using a LABS maneuver or during horizontal flight. In that latter case, a braking parachute was deployed behind the bomb.