when you look at it, there is an unusual shaped fuselage for a
start, a nice elongated teardrop with the ends chopped off,
also plenty of wing area: - yes, this looks like a good
the history of the Boulton Paul P.111A, the Boulton Paul
deltas were the first in Britain to be designed purely for
academic research into the delta planform, to determine the
basic aerodynamic stability of the delta shaped wing.
This was due to the research data gained from the Germans
after the war. Interest was shown into the advantages inherent
in the delta wing. The first flight took place in
October 1950. The wing was designed with the ability to
increase the span by adding two other sections giving three
different spans to the wing, this 34ft, very nearly to a point
at the tip.
first encounter with this model was in the late fifties, when
P E Norman who was one of the first in building ducted fan
models, produced a plan for an I.C. powered ducted fan model
of the P.111A (he also produced a very nice MiG 15).
When asking around if anyone had a copy of this plan I had no
luck, so I had to start from scratch, but as you all know any
good modeller will have some reference
books to hand. After a good three view was obtained this
was scanned into the computer and a working drawing produced
scale? Well I was
looking for the model to be one
piece but small enough to fit in the back of the car; after a
debate how much room we had for transporting 5-6 models to PSS
events, 1/10 scale was chosen as this gave me the following
sizes: span 36" length 32" (the middle of the three
on the full size). This is a handy
scale as you have a good chance of
locating commercial parts i.e. pilots and transfers .
The target weight was 2.251b, which gives a wing loading of
15oz sq.ft. I like to have all my PSS models in the range
14-19 oz/sq.ft as this works best for the type of jets
that I have designed.
main problem was on which wing section to use, fully
symmetrical or a reflex as we'd normally choose for a delta
wing, on the slope don't we! Well I did not, why you ask
because it didn't look right, as it faired into the fuselage,
so I used Eppler 182 for the root and my all-time favourite
Eppler 374 for the tip, with no wash out. By the way
these were not chosen scientifically as I'm not that
knowledgeable; I just, as they say, go with the flow - i.e. if
it looks right it is O.K. [pun intended]
thing to consider built up wing or foam, well as this was
going to be two different wing sections this really meant
using foam. Pink or white, well as I had just acquired a
nice block of foam, no it was not nicked!. Just check
out your local building sites and ask the site foreman nicely
any waste in their skips, it's amazing the sizes they throw
wings were hot wired by using the method common for cutting
delta shaped cores. Put a nail into the building board
attach cutting wire and stretch out about 36" for an
18" core the other end is attached to 1" dia. dowel
this now allows you to swing through an arc, hey presto a set
these were covered with 1.6mm. balsa.
fuselage was made from a central elongated box to carry Rx and
servos, the 3mm formers being attached at approx. 4"
stations up to where the wing leading edge would be.
These formers now had the stringers attached after the two
servos had been installed to provide elevon control and then
skinned with 2.4mm balsa. The front section was hot
wired from pink foam and sanded to shape and skinned with
1.6mm balsa; this was then attached to the remainder of the
fuselage. The wings were now slotted at the appropriate
points and pushed into the central box giving plenty of gluing
area, now it was time to glue on the front end. The fin
was built up to a symmetrical section and also skinned with
it came to the point of what colour scheme to use you have two
choices. The first prototype was all silver and the
second was all yellow with some black trim, and nice large
roundels. I chose the bright yellow one, easy to see in
all conditions as has been proven at the last two events, when
there was some thick mist, so I was still able to follow the
model. Which brings us to the main point - WILL IT FLY
the answer to that one is fantastic! It will fly on the
right slope in 6 mph winds and up to 40 mph if you can stand
upright, inverted is as good as upright !
Conway holds aloft his Boulton Paul P.111a at the Hole
here we have a true delta, that performs on the slope, when a
lot of people thought it would have too much drag but it has
proven to be good at pylon racing also.
thing that was still required was some reflex, not a lot, as
Mr Daniels might say, but I still think I MADE THE RIGHT
DECISION REGARDING WING SECTIONS.
have only one bad comment and this is my own standard of
finish to this model as I had covered it with film and this
was just not right, but I now have an opportunity to rectify
this as I had a nasty crash into a fence post at the last PSS
event. That's the thing with these early jets, they did
not have post-avoidance radar. I hope this has been an
insight into the meanderings of an old modeller.
hope we have a better season next year.