A Scale Model Investigation of Rocket Exhaust Effects on an Improved Saturn V Booster Utilizing Solid Propellant Strap-Ons

Missions currently being considered by NASA beyond the Apollo manned lunar landing will require a larger payload capability than is available with the current generation of Saturn boosters. An attractive method of achieving the desired payload increase consists of adding large solid propellant rocket motors (strap-ons) to existing boosters to augment the thrust from the basic booster liquidpropellant engines. The soundness of this approach has already been demonstrated by such vehicles as the Titan III-C and Thrust Augmented Thor/Delta, where significant performance increases have been obtained within current state of the art and at minimum cost, while simultaneously retaining the proven reliability characteristics of the previously developed basic booster. The possibility of increasing the performance of the Saturn V booster through the addition of previously developed 120-inch solid-propellant rochet motor strap-ons to the S-IC first stage is currently being evaluated by the Marshall Space Flight Center of NASA. One of the items of concern with such a configuration is the possibility of a detrimental alteration in the base environment of the S-IC from that which will exist with only the basic complement of five F-l liquid propellant rockets. For example, interactions between the liquid propellant and/or solid propellant rocket exhaust plumes (a total of nine rocket exhausts are involved) may result in increased flow recirculation and attendant increases in base pressure and convective heating. Further, radiant heating to the base may also be significantly greater because of the presence of the aluminized solid propellant exhaust plumes. In addition to these potential flight problems, consideration must also be directed toward the launch stand environment. Rocket exhaust recirculation from the flame deflector can produce a severe thermal environment in the booster base region during the ignition and lift-off sequence, Launch stand components must also be suitably protected to withstand the 5000 °F exhaust gas impingement as the booster lifts off