Message text written by "Brian Tarmar"
>I am attempting to complete Classic 055 - A kit started by John Grant of
Norwich in '94 and bought by me in July 2000, when John began suffering
---From the dreaded epoxy allergy. 055 was an early conversion to trike, with
an approved (the second I believe) lowering to the rear of the central
tunnel. I hope to fit a WAM 120 if weight can be kept within reasonable
bounds.
Having reached the stage of planning cable routes which separate as much as
possible power from feeders, can I mount the transponder aerial/antenna in
an outer underseat stowage? Either totally within the airframe or
protruding.
I believe this position offers the shortest cable run (in line with design
requirements) and keeps costs down if the more expensive RG400 co-axial is
to be used. I hear tales of "frying the family jewels" with RF (perhaps
the aerial should go under the passenger seat!) and blanking by the engine
when the interrogating station is ahead. Your thoughts please.
<
I wish you luck with your WAM 120 engine. It looks a super piece of
engineering but IMHO it is likely to be rather heavy for the Europa. I
tried to find out the empty weight of the only Europa with the WAM 120
fitted but it seems to be a closely guarded secret which makes me think it
is heavy. I would be pleasantly surprised if it is lighter than the Subaru
variant and some of those reach MTOW with 2 adults and full fuel leaving no
spare weight for baggage.
For the price of a few extra feet of RG400 I would mount the aerial in the
rear fuselage. Any decent transponder can cope with any cable length that
we are likely to use in the Europa. This will leave the underseat stowage
for things that need to be more accessable. Make sure you have a ground
plane of at least 125mm diameter. An easy way to achieve this is to layup 4
layers of 'bid' with a layer of tinfoil in between the third and fourth
layers. Leave a gap in the 'bid' on the fourth layer in the centre to allow
electrical connection. If you make the lay up straight on one edge and bend
it over the edge of the work surface during construction it will provide
its own bracket which can be Reduxed to the fuselage side wall.
Alternatively you could use a piece of aluminium sheet but to make it rigid
enough to stop it flexing with vibration it will be heavier.
Nigel Charles
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