A series of articles on electric flight by Rob Ireland
I shall be using this part of the website to introduce aspects of electric flying and electric models. There is nothing odd or worrying about electric models, in fact this first article I thought should provide a bit of an introduction to electric models to seasoned fliers and beginners alike.
To begin with, a listing of the relevant merits of electrics would be in
order and this is included below.
Some of the models I fly (past and present, frequently or otherwise) are shown
here also.
More specific information on each of them will follow later as I use them for
further articles.
Morane Saulnier Type L
Built March 1999, 47 flights.
Precedent Electra Fly
Parky
Built April 2002, 28 Flights
1. Quiet flying. Silent in some cases.
2. Vibration free. No stresses imposed on the plane from the motor.
3. Clean. No oily mess to clean off the model. No fuel to spill in the car
or in the house. No castor oil smell (is this a disadvantage?). Initial flight
testing can be carried out with the minimum of finishing. Without the need
for fuelproofing, electric models can be flown with bare wood!
4. Models will not lose weight in flight. If a tank of fuel is located some
distance from the centre of gravity, then the C. of G. will move as the fuel
is used. No problem with electric. Motor drive battery can be located without
this constraint. It is usual to allow some fore/aft positioning options with
the battery so that the C. of G. can be adjusted without using ballast weight.
5. Crash repairs are easier, but it’s better yet if you try not to crash!
Without fuel and oil soaked into the fabric of the model, most clean breaks
can be fitted back together easily. Splintered edges should line up with each
other accurately and a squirt of glue has it as good as new.
6. Scale detail. Where this is important, the electric plane scores over the
i/c plane in not requiring the butchery to engine cowls, carried out to accommodate
exhausts and cylinder head cooling.
7. No “dead-stick” situations. The little problems which cause
i/c motors to cut in flight do not exist with electric. Without these problems
to contend with, electric flight can be an ideal starting place for beginners
to model flying. (If the drive battery is completely drained the model is still
landing from a glide, just like i/c.)
8. Multi-motored models are easy to fly. Because one motor will perform similarly
to another of the same type, and neither exhibit a desire to “quit” by
itself, multi-motored model subjects offer no more difficulty to fly than a
single motored model. How about a Mosquito, Ju52, Lancaster, Heinkel 111Z,
or a B36 Peacemaker, on 2, 3, 4, 5, or 6 motors?
9. Electric motors can be restarted on demand. The ability to control the electric
motor in these models from full power to stop is no different to the throttle
control of an i/c powered model. The difference is that the electric motor
can be stopped and started as required. This is essential for a powered glider
where flight duration is important, but it is also a useful feature for beginners
and experienced sports flyers where it can avert a disastrous landing!
1. Underpowered? No, not today. This was true 10
years ago when motors, batteries & controllers were not up to the task. Also
there was a multitude of poorly designed
models for electric power which would only result in crashes. There are many
electric plane “package” deals still around today which are wholly
inadequate when it is considered they are primarily aimed at beginners. Fore-armed
with a bit of knowledge, the newcomer to electric flying can avoid these tempting
pitfalls.
2. Expensive? Another fallacy carried over from 10 years ago. Then, the solution
to underpowered electric models was to buy more expensive motors and controllers.
Today, a good electric model can be had in a number of guises without costing
an arm and a leg. Typically they will require a Speed 600 type motor £10,
an electronic speed controller £25, a 7-cell NiCad battery £28,
a suitable charger £15. Total outlay for equipment that an i/c flyer
would not necessarily have is about £78. A second battery is desirable
to allow flying with one pack while the other is charging. Mini servos instead
of “standard” ones
are better. Weighing about 1/3 that of standard servos they cost about £13
each. Suitable “almost ready to fly” models are available to suit
all tastes in a price band of £50 - £100. So, if you are an i/c
power flyer and want to get into electric, you could spend a minimum of £128.
As a complete beginner to model flying, your requirement regarding a suitable
plane ready to fly would run to about £154.
3. They don’t fly for long! Well, how long would you like to fly for?
On any model flat-out performance only comes at the expense of duration. I
am used to flying for shorter flights than can be had with a tank of glow fuel.
But I can also land, change the battery and be back in the air within 30 seconds!
The high efficiency of brushless motors and the improvements in battery technology
have now eliminated this gap, but it costs a bit more. On the other hand, an
electric glider can fly all day!
If you have internet access, here are some interesting sites;
www.befa.org.uk site
of the British Electric Flying Association.
Membership secretary for further information is;
David Andrews,
2 Gainsborough Road, Kibworth Harcourt, Leicester, LE8 0SG (david@kibworth.fsnet.co.uk)
www.ezonemag.com an informative on-line American magazine. Almost too much information!
Next time;
• How to make a successful entry into electric flight.
• Some appropriate models and equipment.