This the text from a QFI review
that I did back in 1998 (or thereabouts). Things have since moved on and now we have an
EPP 60" pylon league in the UK. The Enigma is no longer the only choice on the market
and it is not the best out there, so choose carefully. Anyway, the Enigma...
For a while now I have been keen to
see the unique properties of EPP foam be utilised beyond combat models as there are
several other areas of our sport that could benefit from the increased durability that EPP
provides. Stan Yeo of Phoenix Model Products has had the foresight to introduce the EPP
Synergy aerobatic model into to his range and recently he has succumbed to public pressure
and brought out the subject of this review, the Enigma 60" EPP pylon racer.
The model was conceived as an
efficient, robust and quick build racer/aerobat providing its pilot with performance
touching on that of non-EPP models yet retaining the benefits of EPP construction.
It’s my job to see whether or not it achieves this rather tall order.
What you get 
All the bits arrive neatly packed
in a compact cardboard box that should withstand the rigours of most postal systems. I
wonder if any manufacturer has ever had a complaint that an EPP kit was damaged in the
post?
Examination of the contents reveals
that not only are you supplied with most of the accessories that you’ll require to
complete the plane but also vast quantities of black EPP dust especially for your spouses
enjoyment.
Once you’ve vacuumed
everything closer inspection shows that the major components are all very good quality.
The EPP wing cores and fuselage sides are CNC cut and the benefits can be seen especially
with the wing which definitely exceeded my expectations when it came to reproducing the
RG15 airfoil. Ply doublers are nicely die cut and the ailerons are from well-matched balsa
of the right weight for the job. The Correx V is neatly cut out and in practise has proved
to a very durable item. Accessories are snakes, threaded metal snake end adapters, a few
stickers as well as plastic horns and clevis’.
Please forgive my lack of
constructional photographs. I had a camera problem and no way was I going to delay
throwing the Enigma together whilst my photographic tackle was being doctored.
In practise the construction is so
straightforward that with a little care, patience and the benefit of Stan’s
instructions no problems should be encountered. In the event of any difficulties Stan is
never further than a telephone call away.
Getting it together
Much of the construction is
completed using Evo-Stik impact adhesive or similar and I confess to being surprised quite
how well suited to the task it is, although ventilation is highly recommended! The
instructions are reasonably comprehensive so rather than give you a step by step account
I’ll focus on the areas where I either deviated or think a little extra clarification
may stop you seeking solace in the Evo-Stik!
Fuselage assembly takes an hour or
so and Stan guides you through the process painlessly. The only area where I saw fit to go
my own way was at the tail end.
The instructions show each elevator
having a separate snake which are then joined together at the servo. On my example the
snakes provided were a little sticky and were discarded in favour of a single pushrod.
When doing this it makes sense to move the elevator servo to the rear of the under wing
bay so that ballast can be added without interfering with the pushrod.
Bearing in mind
that I wanted to squeeze every last mph of performance from the airframe I also made the
elevator linkage internal. This was easily achieved by mounting the V tail in the fuselage
top decking rather than the underneath it. This gives plenty of room for the pushrod to
run freely underneath the V tail. Although often perceived to be a tricky task the
mechanical link to the elevators was easily accomplished using piano wire torque rods
fitting directly into ball links. The photograph shows the linkage except for the buried
torque rod ends, which were remarkably easy to install into the Correx. The internal arm
of the rods should go the depth of 3 or 4 flutes into the elevator and be secured with
5-minute epoxy.
The instructions call for the one
piece V tail to be scored chordwise in the middle and folded. Some triangular balsa
cyanoed at the join gives the required reinforcement and V angle. I found that it was hard
to relieve all the stresses when folding the Correx which meant twists were more likely to
creep into the surfaces. The simple cure was to cut the Correx totally in two and cyano it
to the balsa. The balsa is simply located on one surface at a time and the cyano wicked in
from each side, it works beautifully. The finished tail is glued to the fuselage using
good old Evo-Stick which, along with the tape covering, provides a more than adequate
bond. The elevator servo was simply wrapped in masking tape and glued to the fuselage ply
doubler, after it had been abraded of course.
Wings next and following the instructions produces a
fine set of surfaces in an evening or two. The spars are Evo-stuck into the ready made
slots. The instructions advise that the slots may need a few minutes work to get a perfect
fit. This is simply achieved by wrapping some medium grit wet and dry paper (used dry!)
around a piece of the spar material and running it through the slot a few times. The rest
is straightforward enough although I must admit to using 5-minute epoxy to secure the
front and back wing braces rather than Evo-Stik.
My only other deviations were that
I opted to mount the two wing servos behind the main spar and not in front as the
instructions suggest. My reasoning revolves around collision resistance and less drag
although I have no doubt that Stan’s method would work fine. A small trough is
scalpeled into the bottom surface for the servo wiring to be run underneath the tape
covering to the centre. The kit includes some plastic reinforcement to stick to the top of
the centre section of the wing to stop the rubber bands damaging the EPP. I was slightly
dubious of the durability of the plastic so substituted it for some good old ply that
I’d soaked for a few minutes and then dried wedged up against a radiator to put a
curve into it. This has worked fine but Stan has assured me that the plastic does too, so
it looks like I wasted my time!
The ailerons are triangular balsa
items that are very nicely weighted for the job. It did cross my mind to sand a cusp into
the underside to more accurately reflect the RG15 section but decided that the chances of
doing it accurately enough to make a significant difference did not warrant the effort
involved. Or alternatively I couldn’t be bothered, make your own mind up!
Finishing off
Just a few evenings work had
resulted in a fuselage with correx V tail attached and a set of wings with servos
installed and some ailerons waiting to be hinged. Around two hours in front of the TV was
all it took to cover the airframe, first in the supplied glass reinforced tape and
secondly with the vinyl tape that can be bought from PMP as an accessory. Personally I
wouldn’t entertain the idea of building an EPP model without the vinyl tape as a few
hours in the sun is enough to leave the glass tape looking like an old crisp packet
that’s been poorly stretched over the wing. I can understand manufacturers not
supplying vinyl tape as standard as there are a number of colours available but I would
certainly recommend ordering some with your kit. I have had a glass tape/vinyl tape
covered foamie for over a year that has seen some serious airtime and the covering is
showing no sign of UV degradation causing delamination with the EPP.
The ailerons are top hinged during
the covering. For durability I would recommend taping the top first followed by bending
the surface right back and then taping the underside also. Before doing this make sure
that you have sanded enough off the aileron to allow plenty of down going movement. I
would also recommend investing the extra hour or so to seal all the hinge gaps and the
ends of the correx flutes using diamond tape. Both of these will give a noticeable drag
reduction.
Instead of using the supplied
plastic control horns (I always find them a little flimsy) for the ailerons I made some up
from printed circuit board, long servo arms also work well providing you glue them in the
surface adequately. The photograph shows that where the aileron servo cables exited the
underside on the wing they were taped over so that they emerge at the leading edge. This
has the effect of stopping the wires getting caught in the wingseat as well as preventing
them from dangling around inside and being interfered with by the ballast and elevator
servo. It also lines everything up nicely when the wings are banded on as the wing wiring
plug sits nicely in the RX bay ready to be connected. Instead of using two standard servo
connectors I prefer to use a single 5 pin Multiplex item with the connections soldered and
then potted in epoxy for durability. Experiences show this type of set up fairs well when
the inevitable wing detachment occurs.
With the 600mah 2/3 AF pack in the
nose and the switch embedded in the hatch to save room (see photo) only a little lead was
required to balance the model in accordance with the instructions. Ready to fly weight
came out at 2 ¼ lbs. which flying tests have proven to feel about right, it certainly
would not benefit from being any lighter, so please don’t skip the vinyl tape,
you’ve been warned…
Flying
Initial flight tests were early in
the new year and definitely explored the upper end of the envelope. Winds gusting to 50mph
make the airframe feel awfully light even with the inclusion of all the ballast. Any
worries were completely dissipated when a clubmate volunteered to fly his trimmed Enigma
first. Damn sporting especially considering he’d left his ballast at home! 
To the surprise of both of us his
penetrated well and didn’t resent the lack of ballast at all. Suitably inspired my
Enigma plus full ballast was hurled aloft and cut through the slope edge blowback
effortlessly. As with many of the first flights I have with new models it was a fairly
brief affair. I see no reason to fly a plane set up with responses I don’t like for
any longer than I have to! Time enough to check the CG, control response and
elevator/spoileron mixing and it was back to earth.
Let the refinements begin! Some
weight out of the nose, more down elevator, less up elevator, less snapflap, more down
elevator compensation for the spoilerons and open up the differential menu so that it can
be adjusted in flight. Two minutes later the Enigma was hurled up again and was
sufficiently tailored to my own peculiar tastes to start feeling comfortable with.
Time to have FUN. I have to be
honest and admit that I wanted to enjoy the Enigma but never expected that this quick
build production EPP 60" racer would achieve the levels of refinement that it has.
The second flight started off with some mock pylon racing. First impressions were that I
was flying a pylon racer. A bit draggier maybe and a little uglier definitely but there
was no getting away from the fact that it is accurate enough to fly a pylon course in
complete confidence and provide enough feedback to ask to be fine tuned further.
I really didn’t expect to
spend so much time tailoring the settings in the same manner that I would with a
"normal" pylon racer. I suppose deep down lay a bit of snobbery leading me to
believe that an EPP aircraft could not be refined enough to warrant such attentions.
Sometimes it’s good to be wrong!
A few more landings and adjustments
left me with the Enigma feeling every part a pylon racer, fast, responsive and capable of
changing direction quickly and without undue energy loss.
Anyone who’s ever flown a good
pylon racer will tell you they are also usually potent aerobats and thus it is with the
Enigma. Rolls, point-rolls, loops, square loops, all kinds of eights, rolling circles even
faked stall turn manoeuvres (no rudder remember) were all taken in it’s stride.
What’s more the bouncability of the airframe encourages the pilot to push it in a
manner not often done with more frangible airframes. Indeed for a year or so now when
sport flying in good lift I usually aim to complete a rolling circle using four point
rolls and although I’ve managed it on a few occasions the attempts to success’
ratio is stunningly poor. This is exactly where a model like the Enigma shines as the
fear/cost/breakability factor allows angst free exploration of previously unchartered
territory.
It happened that the first League
BMFA 60" Pylon race of 1999 fell within the period of this review and one of my
clubmates and travelling companions, Paul Jewell, had nothing to fly. Letting him baptise
the Enigma, all be it in a composite environment which it wasn’t really intended for,
seemed like a sensible idea. In time honoured fashion race preparation involved a data
transfer between transmitters immediately prior to the race and a 2 minute
"familiarisation" flight before the off. To cut along story short Paul came
eighth out of 22 competitors and was very pleased.
My Eliminator was involved in a
terminal (for that day anyway) mid-air in the very first turn of my first round (cheers
Adrian!) so I used the Enigma all day as well. In fact by the end of the day another
clubmate was also taking his turn following the demise of his composite ship. All three of
us placed in the top ten despite several more midairs, all of which were shrugged off by
the Enigma.
For me the most telling flight was
the one where I knew all the variables except how they would compare with each other. In
this race there were only two up, Mark Passingham who was flying an Eliminator and myself.
I rate Marks and my own flying skills as pretty evenly matched and I know the Eliminator
to be an extremely competitive racer. The result was almost exactly as I had expected. At
the end of the ten laps Marks Eliminator had nearly, but not quite, lapped my Enigma.
Although the result on paper is definitive I saw this as an exceptionally encouraging
result for the Enigma. To be upwards of 90% as effective as a specialised racer, at less
than half the price and building time yet with much increased durability is quite an
achievement.
Enough performance has been
attained to elevate the Enigma from it’s intended usage in all EPP racing to what I
would consider an invaluable back up racer in standard racing.
One thing that I was expecting to
have to do but it was never necessary was to reinforce the Correx V tail after a mid-air.
Either the tail miraculously escaped contact in all of the Enigmas airborne encounters or
more likely it flexed but didn’t crease. Shame in a way because I’d taken along
some 4mm diameter carbon rods to pop down the correx flutes to reinforce any creases. Oh
well, I’m sure they’ll get used soon…
One final word about ballasting. My
Enigma is set up to accept 12oz of ballast that puts the all up weight to 3lbs. At this
weight the Enigma can be flown in just about anything and in my opinion 3lbs would
represent a sensible weight limit for an all EPP pylon race. For sport flying there is no
reason to exceed 3lbs although for racing in a standard 60" race on a ballistic day
the Enigma feels as though it would happily carry more lead.
I have found that my racing set-up
varies significantly from that given in the instructions and have included my control
movements below so you can take your choice between the two. It should be noted that this
is the racing set up and whilst giving reasonable aerobatics better results are obtainable
with slightly less differential and slightly more snapflap.
Summing up
No designer would envy the prospect
of juggling build time, performance and durability to arrive at a suitable compromise but
in my opinion Stan Yeo has done the job superbly. He has produced an excellent quality set
of components that can be assembled in a week or so of evenings by a relative novice using
the instructions to produce a very practical and rewarding aircraft. Those prepared to
spend the few extra hours sealing gaps, making internal linkages, shrouding wing servo
linkages etc can reward themselves with that little bit less drag and the associated
performance benefits.
I can think of few models with such
a broad appeal. Relative newcomers wanting to try aerobatics or take a step up the
performance ladder from their combat model. Pilots wanting to try pylon for the first time
without the cost or worry of a conventional airframe. Hardened pylon competition pilots
jaded at the thought of yet another re-build. Aficionados sat on the side of a hill
wondering whether the lift is good enough to launch their scale masterpiece desperately in
need of a slope tester.
Personally I hope that model
achieves it’s primary design goal and introduces pilots to the fun to be had pylon
racing. Whether the Enigma is flown in a conventional pylon race or in an all EPP 60"
race you are guaranteed to enjoy the experience.
Specifications:
Span: 1520mm
Wing section: RG15
Construction: EPP, balsa and Correx
Controls: Elevator and flaperons (single aileron servo option shown in instructions)
Servos: Micro’s or mini’s (micros preferred)
Control movements used for racing:
Elevator: 10mm up / 9mm down
Elevator spoileron compensation: 2mm down at full brake
Aileron: 12mm up / 10 mm down
Snapflap: 1mm down / 0mm up at full elevator
Spoileron: 20mm up aileron at full brake
Thermal flap: max 3mm down, proportionally adjust to conditions
The Enigma costs £52.95 inc. P & P and along with other models and accessories is
available from:
PHOENIX MODEL PRODUCTS
3 Salisbury House
Salisbury Road
Newton Abbot
Devon TQ12 2DF
Tel/Fax +44 (0) 1626 332287
E-mail mail@phoenixmp.com
For another Enigma review try Mike
Shellim's excellent pages.
