If there is only one group, then the null tested is that the underlying probability of success is p , or .5 if p is not given. The alternative is that the probability of success is less than, not equal to, or greater than p or , respectively, as specified by alternative . A confidence interval for the underlying proportion with confidence level as specified by and clipped to [0,1] is returned. Continuity correction is used only if it does not exceed the difference between sample and null proportions in absolute value. The confidence interval is computed by inverting the score test.
A propeller that turns clockwise to produce forward thrust, when viewed from aft, is called right-handed. One that turns anticlockwise is said to be left-handed. Larger vessels often have twin screws to reduce heeling torque , counter-rotating propellers , the starboard screw is usually right-handed and the port left-handed, this is called outward turning. The opposite case is called inward turning. Another possibility is contra-rotating propellers , where two propellers rotate in opposing directions on a single shaft, or on separate shafts on nearly the same axis. Contra-rotating propellers offer increased efficiency by capturing the energy lost in the tangential velocities imparted to the fluid by the forward propeller (known as "propeller swirl"). The flow field behind the aft propeller of a contra-rotating set has very little "swirl", and this reduction in energy loss is seen as an increased efficiency of the aft propeller.
#2 The prop hub end of the stock VW crankshaft has a rather large threaded hole bored down the middle of it to retain a bolt for a pulley on the VW engine in the automotive configuration. This hole
goes fairly deep into the crankshaft ….on the outside of the crankshaft (same end) is a keyway groove cut into the OD of the crankshaft …..there is an area of this end of the crankshaft where the threaded hole down the center and the keyway groove almost meet, There is approx 1/8th
of an inch of crankshaft metal between the keyway groove and the threaded hole. The prop hub is slipped right over crankshaft but
does NOT cover this weakened area,
it basically stops right even with this weakened area of the crankshaft. The area I am talking about is just in front of the crankshaft oil slinger disc ….when you install the prop hub you press it right up against the oil slinger disc …..a nice
clean place to break is provided, and that is where they break,
approx. 1/8th of an inch in front of the oil slinger. The crankshaft is almost designed to break here, but this is by accident, NOT intentional, it’s just an automotive part not designed to carry this kind of load. The good
thing is that the metal the crankshaft is made from is very rugged …and you have to create
a situation for it to crack …
and we do just that …read on.