F15-4 Pro Series II 29mm Engines for Model Rockets (2) (EST10031)

The Estes F15-4 is a 29 mm model rocket engine designed for larger single-stage rockets weighing up to 21.0 ounces or 595 grams. Its sustained thrust and four-second delay make it well suited for heavier models that benefit from a smooth, extended boost followed by a moderate coast period before recovery system deployment.

Each package includes two F15-4 engines, two starters, and four starter plugs, providing the essential ignition components needed for multiple launches with compatible model rocket equipment.

The F15-4 delivers a total impulse of 49.61 N-sec with a maximum thrust of 25.26 Newtons or 5.7 pounds. Its thrust duration is approximately 3.45 seconds, followed by a four-second delay before ejection. This combination provides a long, steady ascent and predictable recovery timing for compatible rockets.

Each engine measures approximately 4.5 inches or 11.4 centimeters long and has a 29 mm diameter. The engine weighs approximately 3.59 ounces or 101.8 grams and contains approximately 2.12 ounces or 60.0 grams of propellant.

The F15-4 is a practical choice for compatible larger model rockets, including suitable Pro Series II models, and for hobbyists moving up from smaller D- and E-class engines. Its long burn duration and balanced delay make it suitable for high-performance sport flying and other applications that require sustained thrust. Always verify the rocket manufacturer's recommended engine configuration before use.

Purchasers and users of Estes model rocket engines are responsible for following all applicable local, state, and federal laws, regulations, and safety standards. Model rocket engines must be handled and used only as intended and in accordance with established model rocketry safety practices. Estes Industries, LLC disclaims liability for personal injury, property damage, or other loss resulting from misuse, improper handling, or unauthorized use of its model rocket engines.