You
have already seen the first of the prototypes of this new model, but may
not have realised that it was a model under development. I find great
deal of pleasure in building and flying models, also from experimenting
with different type of designs, not necessarily with much in the way of
mathematical equations, and software modelling, but using tried and
tested aerofoils and applying them to a chosen application
and I do like things to be a little
different.
The
Story So Far......
Some time ago, whilst clearing out my attic I came across
an old flying wing I designed many years ago "Wotsit" and I thought that
it could do with seeing the light of day, maybe a bit of a face lift and
put new life back
into the model. The wings were still good, although the fuselage needed
some attention.
A new lost foam fibreglass fuselage with an integrated balsa fin,
using the techniques much like those
used on the SmArt model was made and offered up to the old wing. It
certainly looked the business and needed to be given an outing up on the
slopes.
In the fairly light conditions on the day, the model performance was ok,
but speed seemed slower that I remembered from the old model. Flight
during higher wind speeds on other occasions also left me thinking that an 'ok' performance
wasn't what I was looking for, it could be better. Whilst the model
looked good, I figured that I also
wanted a slightly different look to the model, and after a
little pondering and sketching a number of images I decided to put
the original wing back in the attic.. It served the purpose of getting me
thinking of a new flying wing, something a bit different..... The old
wing will get used again one day;
I now had other ideas. Fuelled by the fact that to create a brand new wing I
didn't have to create templates to cut the foam cores, I just needed to
work out the parameters and enter these into the computer, introduce the
foam to my CNC wing cutter, press the button and wait for the results.
The
fuselage was given a new tapered wing with an MH 61 aerofoil section,
which I have used on a number of flying wings before. The wing went
together well, vac bagged to glue the obechi veneer to the foam then covered with
some left over profilm that
I already had in the model cupboard. Within a couple of weeks, the model was test flown on my local slope
and proved more promising that the initial swept back design. After a
couple more outings, I decided to
take it on holiday to the Long Mynd, a modelling expedition that had been planned for
a couple of months to meet up with my flying buddy, Neil. Our "frostbite"
news article in February 2013 reflects, in part, on flying of this model.
Tweaking the CofG position and more
flying found that a hyper stall situation could develop in normal
flight, seemingly without provocation. The model still wasn't as slippery as I wanted, but it did show
promise other than the pitch oscillations, however, this did not occur all
the time. I experimented with the
CofG position further, reduced the amount of reflex on the wing but again
something was not quite adding up, so it was back to the drawing board.
Currently the model design has undergone
further change. It keeps the same lost foam fuselage now married to yet another new
wing; similar taper but a different aerofoil section thinned to 8.5%
which works much better than the
previous
versions. In fact, I am quite pleased with the outcome. Speed range is
good but not lightning fast and the wing shows no sign of the previous hyper stall tendencies.
It's very manoeuvrable, with no bad vices even when slowed down with significant
control input, It also maintains a true line whilst inverted and
demonstrate in increase of speed with a slight forward stick pressure to
maintain height. Still not as fast as I'd expected, but it probably
needs a higher wing loading to get it to move and maybe a slightly less
cross sectional area to the fuselage to reduce drag a bit more.
Just last weekend (Apr 2015) I flew it
in a variety of conditions from the hill at Roundway, Devizes,
Wiltshire. Conditions started off on the Friday with
around 15mph South Easterly wind with good lift and some thermal activity. The wind speed,
increased throughout the weekend and gradually moved round to Westerly
on Saturday afternoon and back to a South Westerly direction by Sunday
morning.
Sunday saw wind speeds gusting up to 46mph
where most people would not have even considered
flying in the gusty and sometimes unpleasant conditions.
A group of us had planned a long weekend
on the slopes of Wilstshire and we weren't going to be deterred. Yes it was very windy, but some of us had
flown in much worse conditions on other hills. On the day though, I
think that the vertical component of lift was being reduce by the
horizontal wind component as it was
not easy to get much more than about 20ft height above the slope. "Volitan" the
name given to this model design
coped well with the conditions and given its light weight, kept up
with the lead sled mouldies that had been brought out for the occasion.
I
am currently trimming and tweaking the set up to gain more performance,
but pleased with the model so far. Indeed, so please I have now started
to fabricate the plug to make a formal fibreglass fuselage. This will
have a slightly reduced cross sectional area to reduce drag, which I
also think is a contributory factor in improving the overall speed of
the model.
Yes its a lot of effort, but as I said, I like building
and experimenting with different designs and shapes. I
also like the feeling that when you get something right, it looks and
performs well and its something different to frequent the slopes with
that often turns a few heads and gets people talking.
So what's in the name?
Well most people ask what the model is, if
you don't have a name then that's not a good starting point is it. So
what could I call it?
Going on the shape of the fuselage I
initially thought of a name that would reflect its appearance,
especially the shape of the fin. The name of a
number of sharks came to mind; Mako,Tiger, or even the general name of
Predator but other models have adopted these type of names and they seem
a little too aggressive. The Name "Sharky" came to mind, thinking of
Sharky and George the cartoon characters, then of "Bruce" the character
in Finding Nemo (a Great Film!), but I wasn't quite sure. I think I
wanted a name that was a little more subtle. Then the name Sushi came to
mind which seemed fitting, although this may have been a little too
subtle and tenuous in its connection. Whilst Sushi is the name of the rice, it is
more commonly associated with fish, however, I have another new model
which
has yet to be revealed, that I think the name Sushi would suit better.
Looking around the internet for inspiration for a name that I felt had to be
associated with a fish, I found it, "Volitan".
A species of flying fish - rather an apt name I think considering the
shape of the model.
Well, given the actual names of flying
fish, I could hardly go with Exocoetidae, Meaning family of sea fish
more commonly known a flying fish. More specifically, Exocoetus
monocirrhus or Exocoetus obtusiostris, to name but a few species of
flying fish. Like most people, I didn't do Latin at school and hate
those TV programmes that also insist on using the Latin names for most
things like garden plants etc. For one, I wouldn't know how to pronounce
those names or understand what they actually mean, and would it be a
catchy (no pun intended) name, something that most people might
remember?... Sadly No!
So off with "Exocoetus", Latin for Genus
and retain the actual species name, in this case Volitan. I
think even as a Yorkshireman, I shouldn't have a problem with the
pronunciation, although some might think otherwise. That said, I'm going
for a lay down as I've used too many big words today............
There's more to come with the
development of
this model. Watch this space for further updates in the near future ......
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