I posted this on the Military thread. .. .Impingement of rocket motor debris (remnants of the plug and pieces of the solid propellant) on the tail rotors of helicopters is an old problem. On the Cheyenne they were concerned about not only the tail rotor but also the pusher propeller being hit by debris so they placed deflectors on the exhaust end of the missile carrier to deflect the exhaust downward. But, being of ribbed construction much of the exhaust was allowed to pass through while eliminating the solid parts, which were deflected downward. This was for the TOW missiles.. .. .When the Apache was designed it carried TOW missiles and FFAR rockets and I suggested that they incorporate the same deflectors on the TOW missile carriers and they refused. The Hellfire Missile was made available to the Apache designers later in the design process and the TOWs were eliminated.. .. .Much later while working on the Agusta A-129 I suggested that they incorporate the deflectors on the TOW/HOT missile tubes and they complied. Later on the 129 was equipped with a sighting system similar to the Apache and Hellfire missiles were installed. I do not know if the deflectors were retained.