The SR2 is a development of the SR1, utilising a Tiny Tim solid-fuel booster to greatly increase acceleration in the initial moments of flight.

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The sustainer stage of the SR2 is essentially an SR1, with slightly increased propellant load. As in the SR1(W), the parachute is omitted; the fins are also slightly shrunk to save weight, as the booster stage carries a larger set of fins, while after staging the vessel is fast enough for aerodynamic stability to suffice. The booster burns for approximately 0.6 seconds, during which it accelerates the vehicle up to around 230m/s (515mph) - an acceleration of over 30g.

The lift-off mass of the SR2 is 641kg (1,413lb), of which the booster is 363kg (800lb).

All SR1 launches were from Cape Canaveral, FL. A total of 2 vehicles were launched, both were successes.

The SR2 first flew on February 22nd, 1951, and reached an apogee of 148,136m (92 miles), making it the first man-made object to clear the Kármán line and reach space. At the peak of its trajectory, the atmosphere was too thin to register on the barometer, while the temperature data contained many features intriguing to the eager scientists below.

The descending vehicle was destroyed by Range Safety at 1,200m (3,900ft) altitude.

For its second flight, the SR2 was launched at a slightly greater angle off horizontal; the propellant load was also increased by 20kg (44lb) giving a sustainer burn time of 55 seconds. The vehicle performed nominally, reaching an apogee of 168.8km (104.9 miles) at T+3:44 and providing a good science return. The FTS was activated at T+7:37.

The zero-stage solid booster concept pioneered by the SR2 was subsequently used on the BlueSky 1B.