
THE LAW

	There are no known laws prohibiting the design or 
construction of rocket engines, rocket vehicles or 
accessories, in the United States. However, certain 
communities do have laws prohibiting the operation of 
rocket motors or engines or the free flight of rocket powered vehicles. 
Prior to actually firing a rocket engine the amateur builder shuuld make 
certain that he is not violating established ordinances. If ordinances 
prohibit local testing, a remote site may be needed.
	The amateur builder should keep in mind that a rocket	
engine,	even a small one, is an extremely noisy devlce. If local ordinances 
permit testing in a populated area, the amateur should consider the effect 
of engine operation on his neighbors before the initial firing. The noise of a 
rocket engine comes from the shearing action between the high velocity exhaust
jet and the surrounding atmospere.  Some of the noise can be eliminated by firing 
the engine into a water-cooled duct.  Ample quantities of water must be sprayed 
into the exhaust duct  to rapidly cool the rocket exhause stream and to 
protect the duct itself.  However, this technique restricts viewing of the 
rocket exhaust plume and eliminates one of the unique features of rocket
engine operation.
