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The handset control unit is very similar to a game
pad and is available in Mode 1 or 2. Mine came with a Mode 2 and,
although I am a Mode 1 pilot, I can happily fly co-axial helicopters
on Mode 2. However, I quickly found that the sensitivity of control
required made anything other than basic hovering a bit dodgy.
Phil at Snelflight, in his usual co-operative and helpful way
was able to replace the handset for a Mode 1 version. The handset
actually has a switch on it that says 1 and 2 but this is nothing
to do with Modes and is basically a 'dual rate' switch that gives
quicker responses on the 2 setting.
The handset requires 3 x AAA batteries while the Jump Jet has
a built-in 3s 140 LiPo pack. This is charged via a dedicated AC/DC
charger unit with a LED indicator light to show when the charging
is complete.
In order to keep the AUW as low as possible the wings and tail
unit are made from thin pre-coloured foam. This is glued to the
cross framework that links the PCBA module and the rotors. This
results in a fairly rigid structure but obviously not particularly
'crash-proof' although it is unlikely that the Jump Jet will be
in situations where 'high speed' impacts occur. If we call unplanned
landings crashes then my Jump Jet has made quite a few, and as
a result has suffered some superficial damage. However, new body
sets are available from Snelflight. None of the crashes was actually
due to piloting errors (honestly!) but due to range issues that
I will come to later.
The electronics used in the Jump Jet are obviously quite complex
as three gyros control the four motors and constantly send them
positioning information. This is quite noticeable in flight as
individual motors speed up or slow down. This built-in control
allows the Jump Jet to hover in a quite stable position, although
like all helicopters, the model will soon 'drift' unless actively
controlled. This is where the pilot becomes necessary!
Flying the Jump let is very exhilarating as it feels different
from a co-axial helicopter and one can imagine you are piloting
a Harrier! Before continuing with the performance report I will
just mention the range situation. The Jump Jet used IR control
and is designed for 'small space', 'room size' flying situations
where the walls and ceilings can reflect the IR beam. It is not
designed for flying in a large hall or gym where, as I found,
the beam can 'get lost' over a distance of far less than the quoted
range of 25 ft. I have had lots of email correspondence with Phil
about this but basically the Jump Jet performs perfectly in the
flying conditions for which it was designed. There is a possibility
of a RF version being developed. Remember there are other factors
that also influence an IR system such as fluorescent lighting,
direct sunlight and the operation of other IR devices like TV
controllers.
With the flight battery fully charged the Jump Jet is put on
a level surface and switched on. This allows the gyros to self-calibrate
and set their zero movement references. When the handset is switched
on the PCBA is activated and a red LED indicates that the Jump
Jet is ready for take-off. The instruction book gives ample information
on how to control the Jump Jet and I personally think it falls
somewhere between a co-axial and a FP/CP helicopter. Certainly
I think having some FP/CP experience is helpful as if over-controlled
the Jump Jet could easily get into the dreaded 'wallowing' state.
Once out of ground effect the flight performance is lively and
as with all helicopters and 3-D aircraft the throttle gets plenty
of use. It is very absorbing to fly but I found it needed maximum
concentration plus a bit and very 'busy fingers'. All helicopter
flying is about anticipation and flying the Jump Jet is just the
same. Nose-in flying needs very sensitive use of controls, as
does flying circuits in a small space.
Flying in our school hall caused more range problems than I had
anticipated and I regularly ran out of range, when this happens
the motors cut and the Jump Jet descends rapidly! On another occasion
I flew the Jump Jet more successfully in the same hall during
the day when there were no lights on. The main point is that it
flies perfectly in the conditions for which it was designed.
Phil emphasised the importance of keeping the AUW as low as possible
and told me of several ways to reduce the weight. I had hoped
to fit an U/C to mine and decided to do this after carrying out
some slimming. All that is required to knock off 5g is to remove
the propeller guards, at your own risk of course! Having done
this and test flown the Jump Jet again I made a lightweight U/C
using some small wheels from a Kyosho Minima Cessna. The Jump
Jet with an U/C actually weighs less than it did with the prop
guards and it just seems better setting it down on its wheels
after a flight.
Without the rings I found that the model turned slowly clockwise.
On Phil's advice I replaced two of the rings and the trim was
corrected. Apparently delicate changes to the motor angles are
required in the setting up process and the rings do help to direct
the prop thrust. If you trim, in theory one could attempt to re-trim
the motor angles but I decided against that course of action!
Spare parts are available and I have obtained a set of 'body parts'
from Phil. I've used these to produce a 'camo' set to turn my
Jump let into an military version, pictures later.
A one-car garage gives just enough room to fly circuits, without
the car there of course! Flying nose-in, particularly in a restricted
space is not easy and certainly sharpens up the reactions!
I have had great fun with the Jump Jet and have found it really
fascinating to fly. Even with plenty of helicopter experience
behind me it has been a new and quite exhilarating challenge.
Now how about a larger version on 2.4 GHz? That would really be
something and might even make me abandon my helicopters, just
imaging flying it around the garden!
Well-done Phil and the Snelflight team for bringing out a new
and very imaginative flying machine.
From Q & E F I magazine - September 2008
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