After the success of the Unisat 1 Mk 2 Launcher which brought satellites into orbeit around Kerbal, Mun und Minmus, an upgrade to Mk 3 was proposed. Basically fuel tank size was doubled and small solid fuel boosters were substituted by large solid fuel boosters.

At 0:48 the boosters that had been attached to the 'space stage' hit the quadrupple connector and destroyed it - but the system stayed stable for another 2:10 min and at least 90k m of altitude!
At 2:58 the remains of 'orbit stage' destroyed 'space stage's engine and the design of Mk 3 was labelled "improveable"...