>
>Sorry to see the return of the 1/4" plywood packing is that really a factory
>recomendation?. Quite a few people called me with tales of problems of bent
>Also is there any chance of any technical information on the material from
>which the blocks are made, colour we are told about but these are not
>fashion accessories so the colour is about the last thing I need to know
>about the material unless it is used as an identifier to defrentiate between
>two different spec' materials. IF that is the case then I for one would
>like to see the different specs of the two materials. It may well confuse
>me but we can read and may eventually be able learn enough to make more
>informed decisions about our future actions concerning the u/c if we knew
>the characteristics of the materials we are using. In particular I would
>like to see any feature of the specification which would quantify its
>ability to disipate energy and thus tend to dampen the ocillations of the
>swinging arm. At worst we might be able to decide if, or not, a red block
>with a 1/4" spacer is the equivalent of a black block without packing.
>
>Also many of us have already carved a V into our blocks with black blocks
>is that required or not and if anyone ( I know there are some ) has a red
>uncut block and wish to fit damper kits should they still cut Vs in addition
>to the holes they have to cut from the blocks to fit the dampers?
>
>Is there a sheet explaining the 9 degree ground angle or have I missed it.
>
>Ron S No 33.
>
>
Your E-mail message to us has been sent to all and sundry as opposed to our
1/4" packing
------------
The original shock absorber required a pre-compression to bring the
dimension betrween the centres of the top and bottom plate bearings down to
5". The weight of the aircraft then compressed the rubber further, bringing
the top and bottom plates quite close to the limit stops. To allow further
compression of rubber to take place and not compromise propeller clearance
we added a spacer. Following the drop tests we decided to reduce the amount
of pre-compression such that the distance between the plate centres would be
The materials of the red and black blocks are the same: polyurethane grade
RHS/204/all weather 75=B0 Shore hardness to standard commercial tolerances.
The black block is 3/8" deeper than the red to accommodate the extra 1/4"
required between the top and bottom plate mounting centres.
The reason for the colour change of the block is that we have changed the
manufacturer. The first gave no choice of colour, the second allowed a
(a) to ease identification of the changeover,
(b) as it is in a muddy environment a light colour may be
considered inappropriate.
We don't consider that the rubber block has any ability to dissipate energy
(although of ocurse it will to a degree) which is why we have introduced a
damper system. The red block plus spacer will be slightly stiffer than a
black block without, but when you try to quantify the difference in the real
world i.e. on an aeroplane during a landing, you'd need a very sensitive bum
to be able to feel it.
Since the modification which calls out the requirement to cut the Vees in
the rubber blocks (Mod no 16 dated 7 November 1995) was issued, the tooling
for these blocks was altered so that those later recipients of fuselage kits
had the mod done for them.
The Vee shapes and the dampers are not related. All blocks must comply to
Mod 16, with or without dampers, as otherwise there is the possibility of
over-stressing the reaction plates.
When the shock absorber has been set up correctly and the aircraft is sat on
the gorund ready for flight, the fuselage will be in a nose up attitude of
around 9=B0. Fuel, people, baggage, etc. will all alter this figure. Use it
as a double check if you have an inclinometer handy.
Andy
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Web Site at www.europa-aviation.co.uk
Fax No 44 1751 431706
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