Message text written by David Hillam
>What is the extra weight of such cables?
Would it not be better, instead, to put ballast (similar
weight to the extra cable?) as far back in the tail as
possible, where the longer lever arm would have a greater
effect on the C of G? <
Hi Dave
There is one advantage in having a rear positioned battery. It enables an
easy mounting point for an external power connection (well away from the
prop). I have included this for 2 reasons. Firstly for the first (cold
start) of the day it means that you can use a cheap car battery which saves
loading the relatively small a/c battery ensuring you get airborne with a
fully charged battery. Also if you have a battery problem during a landaway
it is a relatively easy matter to effect a jump start (remember that hand
propping a 912 is not possible due to the gearbox).
The cable weight depends on the gauge used. 4 gauge cable is not light (I
have used it in my Europa). I suspect that, because the Rotax starter motor
is relatively small (50A), you could manage with 6 gauge without too much
voltage drop. I might do the calculations sometime to see if I can downsize
my cable. Should you decide to use any 4 gauge cable I have a few spare
metres left of high quality cable (ex C130 generator cable) which I can
pass on at =A33/m or =A31/ft + p&p. It is worth noting that two lengths of 4
gauge cable fit very nicely within the oval cable trunking available from
DIY merchants. It is a quick and easy job to glass this trunking to the
fuselage side.
As you have a Classic Europa doing the new tailwheel mod apparently helps
the trim situation as well as the handling. In my case I suspect this has
been nullified by fitting the VP prop. I am leaving battery fitting until
after the first weight and balance calculation. This will enable me to
optimise the C of G by placing the battery in the appropriate position.
PS. I have just seen Dave Watts' reply. For your info, he got his cable
---From me so it seems that the weight penalty for 4 gauge is not too bad. His
installation may not have included an ext pwr skt so there may be a small
extra weight penalty for that.
Regards
Nigel Charles
|