Starting on one Mag....
Join Date: May 2002
Location: Canada
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Won't most drop the right out anyway ? I'm just thinking in terms of what has been mentioned above (PA28) on the key OFF - LEFT - RIGHT - BOTH - START ??
Toggle switches were always fun. Pilots on a runup would turn one mag switch to off, get a rough running engine and return complaining that the mag on that switch was bad. They were always puzzled when I would go to work on the other mag and fix the problem. Think about it!
Join Date: Jan 2008
Location: lancs.UK
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Mr. Abraham, Post#14
[QUOTE][The degree of impulse coupling retard is directly proportional to crank speed./QUOTE]
Sir, this is a somewhat ambiguous statement...I would suggest that it's FIXED according to crank -speed.
for those who are less into the technicalities,-
The flame-propagation is, to all intents, at a constant speed. the advance is given to ensure the charge is burning BEFORE the piston reaches TDC , but expands AFTER tdc....once an impulse-coupled mag is set, it will always "release" at the same timing-point...flicking the Mag smartly as the spring is "tripped" each impulse-coupling has an "operating angle "between arresting mag-rotation and release......the salient point is that at slower cranking-speeds, there is less rotation and therefore the piston is further down the bore FOR A GIVEN AMOUNT OF TIME......faster crank= piston quicker to reach TDC = fire needs to get lit earlier. (otherwise gas expands before piston/crank goes over top,stops it, and pushes it back AKA "kickback" )
so, a given coupling will always give the same retard on impulse,irrespective of speed(as long as it's below the point at which the impulse disengages)
My very limited experience DOES extend to Armstrong-starting a vintage Aeronca....I was taught to "crease" no more than the first joint of the index -finger over the prop leading edge and NOT hook it....free hand behind back firm ,straight-arm pull and follow-through....great fun and I still have all my fingers
[QUOTE][The degree of impulse coupling retard is directly proportional to crank speed./QUOTE]
Sir, this is a somewhat ambiguous statement...I would suggest that it's FIXED according to crank -speed.
for those who are less into the technicalities,-
The flame-propagation is, to all intents, at a constant speed. the advance is given to ensure the charge is burning BEFORE the piston reaches TDC , but expands AFTER tdc....once an impulse-coupled mag is set, it will always "release" at the same timing-point...flicking the Mag smartly as the spring is "tripped" each impulse-coupling has an "operating angle "between arresting mag-rotation and release......the salient point is that at slower cranking-speeds, there is less rotation and therefore the piston is further down the bore FOR A GIVEN AMOUNT OF TIME......faster crank= piston quicker to reach TDC = fire needs to get lit earlier. (otherwise gas expands before piston/crank goes over top,stops it, and pushes it back AKA "kickback" )
so, a given coupling will always give the same retard on impulse,irrespective of speed(as long as it's below the point at which the impulse disengages)
My very limited experience DOES extend to Armstrong-starting a vintage Aeronca....I was taught to "crease" no more than the first joint of the index -finger over the prop leading edge and NOT hook it....free hand behind back firm ,straight-arm pull and follow-through....great fun and I still have all my fingers
