>Also anything that accelerates the cranking engine quickly through
and clear of the resonant band should help (i.e. powerful battery, good
contacts, high torque motor). <
This is another good reason for the use of external power for start when
available. I use a car battery rated for diesel use for all my starts from
my base airfield. This gives plenty of current for the starter. I don't
recall having any kickbacks when external power has been used but it has
happened quite often with starts from the internal battery especially on
cold starts when the cranking speed is not quite so high.
For those still building it might be worth considering including a
convenient external power connection point. If your C of G is such that an
aft mounted battery is required mounting a socket just aft of the wing (a
good place for safety) is very straightforward. If you have the battery in
the engine compartment a little more planning is required. For monowheels
aft C of G's are beneficial for take-off and landing as it helps to ensure
directional control with the tail on the ground. It also slightly reduces
drag in the air due to reduced tailplane downforce. The only penalty is the
weight of the extra wire from the battery to the starter (about 1.5lb).
Nigel Charles
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