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An advanced microlight design concept
Part 3- Conclusions, hindsight, publicity and a large
Article by Andrew Gibbs
The project achieved its aims; I had a most satisfying time working on
this project, and I was delighted when the examiners chose to award me
a first class honours degree for my efforts.
Since completing this project more than two decades ago, I have continued
to be interested in aerodynamics and aircraft design, and I've come to
better appreciate the high level of skill, knowledge and experience necessary
to design a genuinely low drag aircraft - skills which I don't have! Nevertheless
I still feel the design concept is of interest, although if I were playing
at being an amateur designer/aerodynamicist a second time around I'd almost
certainly pursue different design concepts. If however I were to stick
with this particular concept, I'd reconsider the following aspects of
a) The wing tips could be changed to a flat plate design
which would be cheaper to make. These might also work better in both aerodynamic
and structural terms.
b) The wings might be better designed as folding rather
than removable structures, making assembly easier.
c) The aspect ratio of the wings could be reduced, making
for a more compact airframe and easier assembly.
d) The aspect ratio of the tailplane should be reduced.
e) Consideration should also be given to giving the tailplane
anhedral so that it would be in the fan wash, making the elevator response
more similar to conventional aircraft, which would add to safety.
f) Rotax engines have become much more reliable over
the years, so I would very likely choose one of these today. To reduce
drag, a cowling should enclose any exposed engine parts such as cylinder
heads to reduce drag. As it stands, the existing air-cooled uncowled engine
would be a source of high drag.
g) A wire brace could usefully run from the base of the
fan duct to the tip of the fin. For a minimal weight and drag penalty,
this would greatly reduce stresses on the boom caused by taxiing on rough
h) As presently designed, the tail wheel would possibly
make ground contact first on landing. To solve this problem, the fin could
be a little shorter.
i) The region where the trailing edge of the lower wing
and the forward face of the intake duct meet form an acute angle, which
would probably generate an area of high drag. This could probably be resolved
using a curved fairing with a design similar to that used to blend the
fuselage/trailing edge junction on a number of WW2 fighters e.g. Spitfire.
j) The shape of the fuselage, particularly the aft portion,
could be reshaped to achieve a lower drag.
At the conclusion of the project, it was displayed at an end-of-year exhibition.
As a result of this, it gained plenty of publicity and further exposure.
For example, it was selected for exhibition at the Design Centre, London.
The project also went to a design exhibition in Japan.
Several magazines featured the project; it appeared prominently
in Design magazine and Engineering magazine and Flight
International both had pieces about White Diamond.
A large RC model
In 1995 a three-page article about the design appeared in Popular
Flying, the Popular Flying Association's magazine (now Light Aircraft
Association). This led to Dr Liam Scott contacting me and asking for permission
to build a large model.
Accordingly, I provided drawings and Dr Scott set to
work at his home in Ireland. One of his first tasks was to build a small
powered (0.049cu in/0.8cc engine) proving model. This flew well and encouraged
him to begin his large Super Tigre 3000 powered example.
At this time, I was enjoying my first ever paid employment
as a pilot, flying a Cessna 207 on survey missions while trying to pay
off my considerable flying debts. One evening it so happened that my employer
had me staying overnight in a hotel in Ireland. Grabbing the opportunity,
I hitch-hiked two hours to meet Dr Scott, discussed and photographed his
fine work and then I hitch-hiked back to my hotel, arrriving just in time
for a short night of sleep before getting back to flying the next day!
Dr Liam Scott built
this 104inch span, 23lb RC model of my design. His
workmanship was of outstandingly high quality.
Dr Scott's model was beautifully built from
moulded glassfibre components. It flew well, but exhibited a minor
pitch stability issue. It ended its days after suffering an elevator
Dr Scott started his
project by building this small powered proving model. It flew well,
and encouraged him to build his large all-moulded model.
The wing tip structure of Dr Scott's model
employed the anti-shear ribs as per my original design.
Dr Scott's work was of astonishingly
high quality. All of these components have been expertly moulded
from carbon fibre.
The model was large and very beautifully built from moulded
carbon fibre components. Dr Scott kindly sent me a video of the model
flying. He reported that it flew well, but exhibited a minor pitch stability
issue. Unfortunately I never witnessed the model flying as it crashed
after suffering an elevator failure before I could travel again to Ireland.
It is unknown whether this failure was connected in any way to the pitch
This realistic shot of White
Diamond has caused many to ask if a full size prototype was built.
One day, perhaps.......