| Each newsletter it is hoped
to have a different PSS modeller putting forward ideas on
their own views on model design and construction. To
start the ball rolling your editor offers the following views
which I stress are strictly one person's ideas and not
necessarily a consensus of opinion.
Most jet aircraft make suitable subjects
providing they have not too many high drag features. It
may be necessary to slim down air intakes, increase wing and
tail areas, providing alterations are done in moderation the
overall 3-view effect should be acceptable and flying
performance considerably improved.
As a general rule I aim for a wing
loading of around 16 oz/ft sq (1 lb/ft sq.) Models of
lower loading seem better for 5-12 mph windspeed and equally
loadings of 20 oz/ft sq need 18-20 mph plus winds in most
cases. Obviously these are only rough guides since
airfoil section plays a significant part in performance.
The most popular airfoil section for PSS
models appears to be the Eppler 374 semi-symmetrical shape
giving good glide and aerobatic performance.
For more docile models and lighter
winds, the good old Clark Y section and its variations are
still much preferred.
Construction wise I prefer the
foam/balsa thin ply doubler design for fuselages and foam
core/veneer covered wings. Both methods seem to stand
plenty of punishment and repairing is quick and easy without
major weight increase. Heat shrink film of the
Solarfilm/Solartex types provide good quick, smart finishes of
relatively light weight.
For quicker fuselage construction the
fibreglass types are preferable, but be careful weight does
not increase too much if repair work is necessary.
A relatively new finish system is brown
paper onto foam block. The paper is applied to the foam
with PVA paste (thinned and lightly dyed) after the foam has
been filled with a thin coat of Polyfiller well rubbed down
after hardening.
| Whilst the
level of finish is hardly as smooth as heat shrunk film,
it is fairly good particularly when given a finishing
coat of emulsion paint or epoxy paint - give it a try,
you could be surprised at the results - I have seen a
90" span Lancaster finished in this way and I will
be using it on the Nimrod next month. |
Alan Hulme with
his Nimrod - 1986 |
Several extra controls have been seen
operating our PSS models over the last two years. These
include high intensity nose lights, strobe lights, airbrakes,
bomb releases and drogue chutes, smoke trails etc...!!
In future months I expect to see
formation flying and dogfight displays taking place as well as
parachute dropping, target bombing runs and high speed jet
aerobatics. The scope for development is enormous.
Do write in and let me have your latest
news and views.
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