After viking 7, the viking rockets were totally redesigned to carry a larger amount of fuel and a heavier payload. Fully loaded the new viking weighed 6.800 kg against the 4.500 kg of the viking 7.
The diameter of the body was increased, the fins were delta shaped and equipped with small roll control jets.
On June 18, 1953 an attempt to launch the Viking 10 went wrong, when the engine section exploded. Some how the rocket team managed to salvage their burning rocket and on May 7, 1954 they were able to launch the viking 10. The viking 10 reached an altitude of 219 km (136 miles) - about the same altitude as viking 7. One of the viking 10 most distinct feature was to large antennas, which were used in an experiment to probe the ionosphere. Along with this Viking 10 carried some other experiments.
The viking program ended with viking 12. It was simply too expensive to use so large sounding rockets.
But that wasn´t the last chapter in the rockets story. The viking rocket was used as the first stage of the vanguard launcher.
About the model:
Eric Truax has made a mod-kit for this model, so it can be fitted with a mmx-rocket-engine:
How to make a flying model of Viking 10
Books and other sources:
The viking rocket story (1955) by Milton W. Rosen
"Science with a vengeance - how the military created the US space sciences after world war II" by David H. DeVorkin:
Rockets of the world by Peter Alway,
NAR drawing 106 by G. Harry Stine
Beggs aerospace - The viking rocket
White Sands missile range museum
NASA Sounding Rockets, 1958-1968, A Historical Summary
Rocket rivalries - Smithsonian Institution