<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> The cases are 1/2" thick STEEL. As stated before, a composite pipe could be placed in the "centerbore". All these issues, are not technologically impossible. Another exo-skeleton for the outside of the case. <br />Posted by kyle_baron</DIV></p><p>What is your pont, other that simply wanting to do things differently ? Making changes to improve performance, reduce cost, or improve reliability makes sense. Making changes that add complexity, increase cost, and increase risk is just plain stupid. Yes it can be done, by people with adequate technical competency. But those same people would not do such a thing, because there is no benefit.</p><p>And no, you cannot just put a composite pipe in the centerbore. First, that would not particularly help the situation, since a composite pipe is not all that strong or stiff in compression. Second it would add a foreign component and material in a sensitive part of the propellant grain, and removal would add a significant hazard -- removal of the original core tooling is a specialized and hazardous operation performed with tooling designed for that operation and also performed remotely for reasons of safety. Third, a composite in the centerbore, even if it could me made to the required tight tolerances (which could not be done practically) would stick to the propellant and create a whole new set of problems -- core tooling is teflon coated and composites cannot take the temperatures required for that process. And no, you could not use grease without damaging the propellant. And fourth, the centerbores are not just a simple hole through the middle of the various segments, and you could not get the pipes out once the segments are joined and the nozzle has been installed.</p><p>And despite your apparent intuition, 1/2 in thick steel is not all that stout, nor is it intended to be. Rocket motor cases are not designed to boiler code, and boilers don't fly.</p><p>Launch systems are relatively complex systems, and there is a very good reason why they are designed by teams of skilled professionals. </p> <div class="Discussion_UserSignature"> </div>