There is a video under RRC2 mini downloads that show you how to program the unit. Very helpful to get you past the confusion.
As stated it is ready to use out of the box EXCEPT: The mach delay is set at zero [0 default],if you plan on any flights that MAY exceed mach.8 it is advisable to set the mach delay to 4 seconds. [for most flights] Meaning if you put larger motors in your rocket , this comes into play. Since you have not given us the full information on your flight,[ type kit or size,weight diameter, motor flown ] I cannot tell you if you are at risk or not.
What happens is: when rocket begins to enter mach a shock wave develops that can give false readings to the altimeter. Motor burnout is usually where max speed happens. If this coincides with mach or approaching mach, the shockwave can trigger false readings & the altimeter can fire your apogee charge while the rocket is traveling at it's highest speed resulting in very bad things, zipper the airframe, strip the chute etc.
The mach delay postpones any readings for the time set, thus preventing charges from firing. After the 4 seconds[in this case] the unit continues functioning as designed. Hence the term "mach delay" delaying readings until rocket has passed through the mach phase.
The larger the motor and faster the anticipated flight, the longer the mach delay is set. For most beginners flying altimeters I find 4 seconds just about right. This phenomenon requires a lengthily explanation to cover all aspects, I'm just giving you the simple version.
Some altimeters you must set the delay, some are mach immune by design, some use barometric readings to function [like this one] others use accelerometers instead,[they are also mach immune]. There is no right or wrong way, just different approaches to design.
Last edited by blackjack2564; 19th April 2012 at 12:14 AM.
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