UK - British Electric Flight Association - ef

ELECTRIC FLIGHT U.K.
ISSUE No. 90 AUTUMN 2007
THE MAGAZINE OF THE
BRITISH ELECTRIC
FLIGHT ASSOCIATION
56
E.F.-U.K.
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– MAIL ORDER –
SPORTS ELECTRIC FLIGHT
FANS AND GEARBOXES
www.fanfare.f9.co.uk
GEARBOXES
FANS
THE HOME OF ....
Morley ‘Jet Elec’ Fan .............................. £15.00
WeMoTec Micro-Fan (280/300/330) ..... £14.00
WeMoTec Mini-Fan (400/480) ............... £28.00
WeMoTec Midi-Fan (540/ 600/930) ....... £38.00
MOTORS
MPJet Brushless motors; 9 motors; outrunners,
inrunners & geared; 280 to 700 .... £40.00 to £58.00
WEP Turbo 10 ....................................... £55.00
Fanfare Silver 16T & 20T ...................... £34.00
Fanfare Powermax 40T ........................ £38.00
Speed 600 8.4v BB SP .......................... £17.00
Speed 600 8.4v Race ............................ £22.00
RE 380 / Rocket 400 ................................ £5.00
Speed 480 BB ........................................ £21.00
Pro 400 .................................................... £5.00
Pro 480 HS ............................................... £6.00
Pro 480 HS BB ......................................... £8.00
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Areas for all types of glider, electric, fuel planes plus car and
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Galleries of hobby photos from modelers all over the world
E-Flight mailing list – thousands of members world wide!
Classified ads
MOTORS / GEARBOXES
Speed 400 FG3 ..................................... £17.00
SpeedGear 400 4:1 Inline ...................... £38.00
SpeedGear 480 3.45:1 .......................... £55.00
SpeedGear 600 2.8:1 ............................ £51.50
SpeedGear 700 2.7:1 9.6v .................... £70.00
SpeedGear 700 Neo .............................. £92.00
Mini-Olympus & RE380 .......................... £12.00
Olympus & 540 ...................................... £19.00
Jamara 600 2.9:1 ................................... £24.00
Jamara 650 2.9:1 ................................... £26.00
PROPS
M.A. Folding
M.A. Wood Electric
CHARGERS
Speed 1 Pulse / Pk
Det 4-8 cells ........................................... £27.00
Speed Ex Digital
as above with discharge ...................... £55.00
Simprop 25 cell .................................... £100.00
Carbon Folders
(Perkins)
Slimprops
APC Electric
(full range available)
Wheels, Wire, Servos, Fuses, Caps,
Powerpole, 4mm & 2mm gold conns.
Three Separate In-depth Webzines…
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Max Neo 13Y 1430 rpm/v ................... £160.00
Max Neo 13D 2470 rpm/v .................... £160.00
Maxu 35D, 21 Cell Controller ............... £140.00
Maxu 35C, 25 Cell Controller ............... £180.00
Superbox 1.6 to 4.28:1 ......................... £50.00
Monsterbox 4 to 6.8:1 .......................... £60.00
Motor Mount ........................................... £12.00
Master Airscrew - 2.5, 3, 3.5:1 ............................. £16.00
MP Jet Planetary - 3.33 & 3.8:1 - 400 / Pro 480 ...... £28.00
MP Jet Planetary - 3.33 & 3.8:1 - Speed 480 ........ £28.00
MP Jet Planetary - 3.33 & 3.8:1 - 540 / 600 ............ £28.00
MP Jet Plastic BB - 4 & 5:1 - 280 / 300 ...................... £8.00
MP Jet Plastic BB - 3, 3.5 & 4:1 - 400 / Pro 480 ......... £8.00
MP Jet Plastic BB - 2.33, 3.5 & 4:1 - Speed 480 ..... £10.00
MP Jet Plastic BB - 1.75, 2.33 & 2.8:1 - 540 / 600 .. £15.00
Mini Olympus ............................................ £8.00
Olympus ................................................. £12.00
EZonemag.com - rcpowermag.com - liftzone.com
Regular columns and HOT NEW PRODUCT reviews in all areas of RC
YEARS of articles archived
12x8 ................ £14.00
15x12 .............. £15.25
10x6/10x8 ......... £4.25
11x7/11x9 ......... £4.50
12x8/12x10 ....... £5.00
13x8/13x10 ....... £5.25
7x4 .................... £6.00
8x4 .................... £6.00
11x8 .................. £9.00
8x4, 8x6, 9x6 .... £3.50
5½” - 12” dia . £3 to £4
13” - 20” dia £5 to £15
Selection of Graupner & Aeronaut
folding & fixed props.
FANFARE • 18 HILLSIDE ROAD • TANKERTON • WHITSTABLE • KENT • CT5 3EX
‘Sports Electric’ Helpline - Phone / Fax: (01227) 771331 - E-mail: john.swain1@virgin.net
Now online at - www.fanfare.f9.co.uk
www.rcgroups.com
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B.E.F.A. Sales
BEFA Round, Coloured Rub-down Decals - Ultra-thin & light - 50p each
EF-UK Back Issues - Issues 71 to 73 and 75 to 85 are available to BEFA members at £3.00 each,
or £5.00 each to non-members. These prices include UK P&P, overseas rates on application.
Reprints of earlier issues may be available to special order at slightly higher cost, contact the Editor
for details (see page 4).
EF-UK Index. A comprehensive index of EF-UK, from issue 28 to date, is available by sending
a £1 coin to cover copying and postage cost.
Binders:- are available to hold 8 to 12 issues of Electric Flight U.K. Produced in dark blue with
gold lettering on the spine, these cost £4.50 each including U.K. postage. Please add £1 for
European postage and £2 for Worldwide postage.
Please send all orders to The Editor of EF-UK at the address on page 4.
Sweat Shirts & Tee-Shirts: Stock of these is now almost all gone - please contact Robert Mahoney
regarding remaining stock, sizes and prices.
PLEASE REMIT IN STERLING ONLY,
WITH ALL CHEQUES MADE PAYABLE TO B.E.F.A.
Electric Flight - U.K.
Issue 90 - AUTUMN 2007
"To Encourage and Further all Aspects of Electric Model Flight in
the British Isles and Elsewhere" - B.E.F.A. Constitution
CONTENTS
BEFA Committee 2006/7 ......................... 4
Chairman's Chatter ................................ 5
Current Lines ........................................ 5
BEFA Technical Workshop ....................... 6
New Venue BEFA Technical Workshop ....... 7
Efficiency Problems ................................ 8
Pillerton Hersey Fly-in ........................... 11
V for Vengeance ................................... 20
New-2-U ............................................. 23
A Dayin the life of an ‘Aeromuddler’ ........ 32
TLC from your TLO .............................. 36
A Cautionary Tail ................................. 41
FlyCat by Haoye Model - Part 1 ............. 42
Electric Flight Calendar ......................... 46
Wings and Wheels ................................ 50
For Sale / Wanted ................................ 49
Wanted by the Editor ............................ 52
New to Electric Flight? Start Here ........... 53
BEFA Sales .......................................... 54
Advertisers Index ................................. 54
Cover Photo: Taken by Robin Andrew at the Pillerton Hersey Fly-in
Advertisers Index
Next Issue: The copy date for the Winter 2007 issue is 20 December2007 with
the magazine due for publication by January2008.
BEFA Sales ....................................................................................... 54
Fanfare .................................................................. Inside Back Cover
For Sale / Wanted ............................................................................ 49
New-2-U ............................................................................................ 23
RC Groups / E-Zone .........................................Inside Front Cover
Traplet ................................................................ Outside Back Cover
EF-UK advertising rates are £25 per inside or outside cover page,
£20 per full page, £10 per half page, all per issue.
Contact the EF-UK Editor for more details (see page 4).
54
E.F.-U.K.
DISCLAIMER
B.E.F.A. and Electric Flight U.K. wish to point out that the content, techniques and opinions expressed
in this magazine are those of the individual authors and do not necessarily represent the views of
either the Editor of this magazine or B.E.F.A. and its committee.
© All information in this magazine is copyright of the authors. Any request to use information
from this magazine is to be made to the editor (contact details overleaf).
All reasonable care is taken in the preparation and compilation of the magazine, but B.E.F.A. and
its committee cannot be held liable for any error or omission in the content of this magazine or
any subsequent damage or loss arising howsoever caused.
To allow proper appreciation of the photographs used, colour copies of them will be
posted on the B.E.F.A. website after publication of this magazine. If you can, check
them out at www.befa.org.uk
3
E.F.-U.K.
BEFA Committee 2006/7
Chairman
Robert Mahoney
123 Lane End Road, High Wycombe, Bucks. HP12 4HF
Email: robert@rlmahoney.co.uk
Secretary
Webmaster
South West Representative
Jan Bassett
111 Plantagenet Chase, Yeovil, Somerset BA20 2PR
Tel. 01935 472 743
Email: sec@befa.ef-uk.net or webster@befa.ef-uk.net
Treasurer
Membership Secretary
Northern Representative
Bob Smith
1 Lynwood Avenue, Tollesby, Middlesborough, Cleveland. TS5 7PD
Email: bob.smith007@ntlworld.com
EF-UK Editor
Jill Day
6 Starboard Walk, Littlehampton, West Sussex, BN17 6QL
Email: editor@befa.ef-uk.net
Events Co-ordinator
Terry Stuckey
31 Dysart Avenue, Kingston-upon-Thames, Surrey. KT2 5QZ
Email: terrystuckey@blueyonder.co.uk
Midlands Representative
Roger Winsor
14 Butler Gardens, Market Harborough, Leics. LE16 9LY
Email: Rogerwinsor7@aol.com
Welfare Officer
Southern Representative
Dave Chinery
251 Station Road, Hayes, Middx. UB3 4JD
Email: DavidDchinery@aol.com
Indoor & Free-Flight Rep.
Gordon Tarling
87 Cowley Mill Road, Uxbridge, Middx. UB8 2QD
Email: gordon.tarling@ntlworld.com
Technical Liaison Officer
Alan Bedingham
17 Highcliffe Close, Wickford, Essex. SS11 8JZ
Email: bbba18333@blueyonder.co.uk
Public Relations Officer
John Thompson
19 Park Avenue, Liversedge, West Yorks, WF15 7EQ
Tel. 01924 515 595
Email: johnty99@ntlworld.com
Safety Adviser
David Beavor
34 Chestnut Close, Brampton, Huntingdon, Cambs., PE28 4TP
Email: wbeavor@connectfree.co.uk
Please enclose an SAE with all correspondence to the committee.
4
E.F.-U.K.
New to ELECTRIC FLIGHT?
START HERE . . . . .
You may be taking up Electric Flight for the first time or you may be converting from another
discipline. Whatever your situation, help and advice is available. BEFA has prepared an information
sheet which details further sources of information which you may find useful when just joining
the hobby. To receive a copy, please send a Stamped Addressed Envelope (S.A.E.) to Robert
Mahoney, address on page 4.
BEGINNER'S GUIDE
A Beginner’s Guide to Electric Flight is available, which explains many of the ‘Mysteries' of
Electrics’ and will, hopefully, set you off on the right foot. Please send £3.00 per copy required to
The Editor of EF-UK at the address on page 4. Please add £1.00 extra for overseas postage and
remit in Sterling. Cheques should be made payable to BEFA.
TECHNICAL HELP SERVICE
Technical help is now available again for the use of all members. We regret that no telephone
service is available, but all questions in writing (or email) will be answered by our Technical Liaison
Officer (TLO). Please refer your queries to our TLO, to the postal or email address on page 4. If
sent by post, please ensure that you include an S.A.E. for a reply.
CONNECTIONS SERVICE
Requests are frequently received from members who wish to be put in contact with other members
living in the same area. The easiest method of doing this is to place a free 'wanted' advert in the
classified section of this magazine. Alternatively, a request may be made IN WRITING to the
Membership Secretary who is allowed to divulge such information to members ONLY. Please
supply as much information about your location as possible and please remember to include an
S.A.E. for your reply.
B.E.F.A. MEMBERSHIP
Membership of the Association is open to all. Those who are not members of BMFA (our
national controlling body) will have a subscription to EF-UK membership with none of the other
benefits. Overseas members are very welcome and will be classed as full members if they belong to
their own national controlling body.
CONTACT
For full details, please send an S.A.E. to the Membership Secretary (address on page 4) requesting
a membership application form. Those with Internet access may visit the B.E.F.A. website at
www.befa.org.uk where you will find all the membership information you should require and a
application form.
E.F.-U.K.
53
Wanted by the Editor
any of the following (see page 4 for contact details):
•
General / Technical Articles.
•
Hints & Tips.
•
New Product notifications.
•
Product Reviews.
•
Photographs of your models.
•
Electric Flight Event Reports.
•
Any other item of interest to electric model aircraft flyers.
Please send colour Digital photos or photographic prints (6” x 4” or
bigger) to the editor. If possible, please do not send inkjet prints as too
much quality is lost during the printing and scanning process.
If you have no way to email or write the files to a CD, please contact the
Editor for other options.
Photographic prints supplied will be returned, unless specified otherwise
(as long as you give a return address).
Digital photos should be sent at the highest resolution possible, in
colour, and preferably uncompressed. Where compression is
unavoidable the camera should ideally be set to the lowest compression
possible and at the maximum resolution. Digital photographs can be
emailed to the Editor at editor@befa.ef-uk.net
Readers always like to know what equipment is fitted to models so they
know what combinations work well (or not so well). Therefore please
include as many details of the models in the photographs as possible,
but ideally at least wing span, wing area, motor(s), gearbox(es),
propeller(s) or fan(s), battery pack(s) used & the flight performance.
Where articles are produced on a word processor package, please send
an electronic copy - it make the Editors job much easier and quicker.
Ideal formats are Microsoft Word (any version), Works word processor,
WordPad or Notepad. Other formats can be accommodated, but please
contact the Editor first.
52
E.F.-U.K.
Chairman’s Chatter
Welcome to our second internet issue of
Electric Flight UK. I was going to ask Jill,
your editor, to use the following in place of
my chairman’s speak for this issue.
This page is intentionally left blank
You may ask why I am being flippant as to
the above statement. Well at this year’s
BMFA Nationals and other events (and
loads of phone calls), I was asked by
members why they had not received their
copy of the latest magazine. When I asked
if they had read the last posted copy of it,
they all said no! I do understand that some
members are not on the internet and I am
printing a few at great expense to the
association.
I would like to say, we would all like the
hard copy of the magazine dropping
through the letter box four times a year, but
to date we
haven’t found
a rich
benefactor (any
idea’s folks) to
help in paying
the printers
invoice!
I have just applied to Middle Wallop, for
the 2008 dates for our weekend of flying,
on possibly the best site for flying in
Europe.
I hope to see you all at the Technical
Workshop in November, where you are
welcome to chat to myself, or to any of the
committee members, who will be there.
Please remember, it will be at a new venue
in Kenilworth.
Keep the watts up and safe flying
Robert Mahoney
Current Lines
Welcome to the second electronic version
of your magazine. As always there is
something for everybody, including a spot
of poetry, and a report from Robin
Andrew, on the 23rd Pillerton Hersey fly-in,
which includes some superb photographs.
Of course there are the always popular,
and regular contributions, from the
‘resident’ experts.
very important
BEFA Technical
Workshop. This
is being held on
Sunday 4th
November
2007. Please
also make sure
you watch out for the change of venue!
Do make sure you look on pages 6 and 7,
as full details are now available for the
Enjoy the read
Jill Day
E.F.-U.K.
5
BEFA Technical Workshop
Sunday 4th November 2007
NEW LOCATION!
BEFA Technical Workshop at Kenilworth School and Sports College, Leyes Lane,
Kenilworth Warwickshire CV8 2DA (see website for location details).
The OS Grid Reference is SP3072 and you can use this at
www.ordnancesurvey.co.uk/oswebsite/getamap
The doors will open for traders to set-up their stands at 8am, with the doors opening to
the public at 9.30am. All the usual features:
Technical Presentations: There are three talks organised, “The Black Art” by Graham
Iredale, “BMFA and Electric Flight” by Manny Williams/Dave Phipps, and “Battery
Testing for Competition Flyers” by Paul Bardoe.
Traders’ Fair: The invitations for traders are being processed, we will put an updated list
on the website. Any traders wishing to attend that have not received an invitation should
contact the Secretary, Jan Bassett secretary@befa.ef-uk.net for details and to reserve
tables.
Bring & Buy Stall: As usual the Bring & Buy stall will be run. Items can be registered
and left at the stand from 9.00am, but trading starts only once the main doors open. If selling
items please complete a copy of the registration form available on website. Please do not
complete a separate form for each item, although multiple forms can be used if more space is
needed. It is also essential that items are labelled with a minimum of your name & the
asking price.
Wings and Wheels 2007
Raffle: The raffle will take place as normal, with prizes being supplied by the traders.
The draw will take place immediately prior to the last technical talk.
Tickets: We have kept the ticket prices the same for this year.
The 2007 prices are:
*£7.00 in advance £9.00 at the door.
Mail orders for advance tickets must include an SAE for return of the tickets. Please also
include a contact telephone number in case of queries.
Mail order requests should be sent with a cheque payable to B.E.F.A., to:
TWS Tickets, 111 Plantagenet Chase, Yeovil, BA20 2PR.
Alternatively advance tickets may be purchased using the PayPal button on the
website. Other online payments methods are available, contact
Jan Bassett sec@befa.ef-uk.net for details.
6
E.F.-U.K.
Wings and Wheels 2007
E.F.-U.K.
51
Ticket orders received before 29 October 2006 will be posted. After that date the tickets
will be available for collection at the door as they may not arrive on time otherwise. Any
questions on ticketing should be made to Jan Bassett secretary@befa.ef-uk.net
*There is an additional charge of 25p per ticket and a handling fee of 50p per order for online
tickets. This additional charge is due to the fees payable to PayPal and to cover postage of
tickets. This still represents a good saving especially as you you’d have to pay 2 lots of
postage if applying by mail.
2008 DATE ANNOUNCEMENT
The Organisers’ of Wing & Wheels Model Spectacular would like to announce
dates for the 22nd event to be held on
Saturday and Sunday 28th & 29th June 2008
at North Weald Airfield, Nr Epping, Essex. England.
As many of you already know this event was first held at North Weald Airfield in
1986, and has become on of the most respected and popular model shows in
the UK Wings& Wheels. It has a well deserved reputation for organising an
exciting show with increasing numbers of spectators, display pilots and Traders
returning year after year.
TECHNICAL WORKSHOP 2007
Sunday 4th November
CHANGE OF VENUE
Although the Royal Spa Centre has served us well for the last few years it has become
too expensive for our limited finances. Your Committee therefore decided to seek a more
economic location and have found one only a few miles to the North at Kenilworth
School and Sports College.
The address of this location is
Upper School, Leyes Lane
Kenilworth
Warwickshire, CV8 2DA
This is a sketch map of the location
As usual the 2008 show will boast magnificent Model Flying Displays – Jets,
Helicopters, Scale, Electric, Indoor Flying Displays in a large marquee, a HUGE
Model Trade attendance, Model Boat Pool and marquee with displays,
probably the countries biggest and best Bring & Buy for modelers
and loads more.
Watch the Model Press for more information over the next few months.
For more information you can contact us on: Tel/fax: (Int. ++ 44) (0)1480
462265 or email: Email:wingsnwheel@dial.pipex.com
Or visit our Web Site: www.wingsnwheelsspectacular.com
Designaction Limited, PO Box 284, Huntingdon, Cambs PE28 9WT, England
For more information check the Events Diary and the BEFA Website
50
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7
FOR SALE / WANTED
Efficiency Problems
By Bob Smith
M
ost modelers (and electric
modelers in particular) realise that
the energy we use to power our
model aircraft is limited. It is limited in
several areas, but these limitations usually
manifest themselves in terms of flight
performance and duration. In electric flight
we use an on-board battery to provide the
energy to drive a system which results in
the rotation of a propeller (or fan or rotor
etc.) which in turn provides the thrust
essential to flight.
One of the disadvantages of early electric
model flight was that we had VERY limited
amounts of energy available in our flight
batteries, and we therefore had to be very
careful not to waste any. Even now, with
batteries, motors, etc. which are many times
better than in the early days, it is good
practice to minimise losses so far as is
possible. The way in which most technical
systems are assessed for energy waste
(including your home for example) is by
expressing the numerical values in a
percentage figure which we normally refer
to as “Efficiency”. It then follows that the
higher this value, the less are our losses,
and since most of the energy losses are
converted into heat, the cooler will our
power-train (battery, ESC, motor etc.)
operate.
It is possible to theoretically calculate the
efficiency of the power-train, and you may
have seen some examples of this type of
calculation, but it is a very complex
relationship to analyse. Even if you deal
with each component in turn and then
combine the results it is not a simple
process. You have probably seen graphs
which, for example, plot the efficiency of a
motor against some other variable such as
Member's Sales & Wants
FOR SALE
WeMoTec Midi-fan fitted with an Aveox 36/24/2 sensorless brushless motor Price £70
Contact Jim Horne HORNEGb@aol.com or phone 01388 819 638
21 Jun 07 - JETI FM 7 Channel Receiver (REX 7 MPD), excellent condition, 3 months
old used for 15 min flight (no crashes), £25. Light weight (Microprocessor Pulse
Decoding).
Contact Keith Day kday1@sky.com or phone 01903 714 711
...and WANTED
Wanted by Ray J Donno (Exeter) , Maxcim N32-13Y motors, Maxcim 35C-25NB controllers
and Maxcim motor mounts.
Contact Ray rd018b4702@blueyonder.co.uk or phone 01392 666 912
Dave is trying to find a pair of William’s Brothers, 6" diameter, vintage style wheels
(faired-over spokes). Not necessarily new but must be in good condition. Fair price paid.
Money waiting!
Contact Dave Chinery daviddchinery@aol.com or phone 0208 573 4687
If you have an electric flight event you want to have
included, please send an email giving the details to
webmaster@befa.ef-uk.net
8
E.F.-U.K.
E.F.-U.K.
49
INDOOR R/C FLYING2007/8
Provided by the BMFA Northern Area
GARFORTH SQUASH & LEISURE CENTRE
Ninelands Lane, LS25 off the A63 Leeds-Selby Road
Saturdays
2.15 to 5.15 pm
Oct 6th; Nov 3th; Dec 1st;
Jan 5th(2to5pm); Feb 2nd; Mar 1st
2.15 to 5.15 pm
5 badminton court size with high ceiling
Licensed Bar, refreshments available
No smoking
Separate slots for
Slowfly
Aerobatic
Scale
SMALL Helicopter Sub 150
and equivalent brushless motors only
Any legal frequency
Proof of BMFA membership essential.
No free flight or IC
Spectators welcome on the observation balcony
Pilots £5.00 Juniors £2.00
Spectators (on balcony) £1.00
RPM or power input, with the suggestion
that the motor should be set up so that it
operates at the peak of the curve and
hence at maximum efficiency.
There are certain advantages in doing so,
such as the cool operation mentioned
above, and you will certainly prolong the
power-on duration of the system i.e. the
flight time, but the disadvantage is that the
model performance is likely to be
disappointing, and this is the crux of the
matter. To put it into common parlance,
“Efficiency is cool man, but power is
exciting!” Most of us fly model planes
because we enjoy doing so, and the more
exciting the flight, the more enjoyable it is
(excluding crashes of course). Even those
of us who do not take part in competitions
and are not trying to climb higher or fly
faster (or even, in some cases, fly longer)
than others still want our models to
perform with authority. We may not want
to fly flat-out all of the time, but we usually
want to be able to do so when the
occasion arises.
Power to the People.
Remember that efficiency curve? What
happens if we change the parameters so
that we move along the curve and away
from the peak? We already know that
operating at the peak will only provide us
with moderate power so there is no point
in moving to the left of the peak as this will
reduce the power even further as well as
reducing the efficiency. If, however, we
move to the right then we are increasing
power and RPM, and the model is starting
to fly with authority. We are operating at a
reduced efficiency (which generally means
more losses in the form of heat and the
components in the power train will get
hotter) but the magnitude of the reduction
in efficiency depends on the shape of the
curve. If the system has a steep efficiency
curve (typical for a brushed motor) the
reduction can be significant. In extreme
cases the reduction in efficiency can be so
Contact
John Thompson 01924 515595
johnty99@ntlworld.com
or
http://www.na-bmfa.org/
48
E.F.-U.K.
Photo: Robin Andrew
E.F.-U.K.
9
large that you are using more power but
getting less performance.
If the efficiency curve is flat (typical for a
brushless motor) then the loss of
efficiency can be so small that it can be
more or less ignored. Now you know one
of the reasons why brushless motors are
more flexible than brushed (i.e. they will
operate efficiently over a much wider range
of RPM), and also why they tend to run
cooler at the same power levels. You
should still arrange for a flow of cooling air
over the power train components, high
temperatures can be a killer and should be
avoided if possible. Of course the situation
is complicated by the fact that the electromechanical design of brushless motors
means that they have higher efficiencies
than brushed motors in general, but the
principle still applies.
I know, I know, principles have a habit of
letting you down on the landing approach,
but that’s where good pilots replace
principles with reflexes (better known as
experience for us more senior citizens). I
did not set out here to give a lecture in
electric power train theory (stand up that
person at the back who laughed out loud!)
but just to plant a few seeds regarding the
dissemination of knowledge. You never
know just when these might come in
handy.
Bob Smith
membership essential. No free flight or IC.
Spectators welcome on the observation
balcony. Pilots £5.00, Juniors £2.00,
Spectators (on balcony) £1.00. For more
information
Contact:John Thompson 01924 515 595
email: johnty99@ntlworld.com or
www.na-bmfa.org
balcony. Pilots £5.00, Juniors £2.00,
Spectators (on balcony) £1.00. For more
information
Contact: John Thompson 01924 515 595
email: johnty99@ntlworld.com or
www.na-bmfa.org
2008
Kenilworth School and Sports College,
Leyes Lane, Kenilworth
Warwickshire CV8 2DA
Please note the new location
January
5 BMFA Northern Area Indoor RC Flying
at the Garforth Squash & Leisure Centre,
Ninelands Lane, LS25 (off the A63, LeedsSelby Road). Saturdays 2 to 5 pm. 5
badminton court size with high ceiling.
Licensed Bar, refreshments available. No
smoking. Separate slots for Slowfly;
Aerobatic; Scale & SMALL Helicopter
(Sub 150 and equivalent brushless motors
only). Any legal frequency. Proof of BMFA
membership essential. No free flight or IC.
Spectators welcome on the observation
balcony. Pilots £5.00, Juniors £2.00,
Spectators (on balcony) £1.00. For more
information
Contact: John Thompson 01924 515 595
email: johnty99@ntlworld.com or
www.na-bmfa.org
February
2 BMFA Northern Area Indoor RC Flying
10
E.F.-U.K.
24 BEFA Annual General Meeting 2008
March
1 BMFA Northern Area Indoor RC Flying
at the Garforth Squash & Leisure Centre,
Ninelands Lane, LS25 (off the A63, LeedsSelby Road). Saturdays 2.15 to 5.15 pm. 5
badminton court size with high ceiling.
Licensed Bar, refreshments available. No
smoking. Separate slots for Slowfly;
Aerobatic; Scale & SMALL Helicopter
(Sub 150 and equivalent brushless motors
only). Any legal frequency. Proof of BMFA
membership essential. No free flight or IC.
Spectators welcome on the observation
balcony. Pilots £5.00, Juniors £2.00,
Spectators (on balcony) £1.00. For more
information
Contact: John Thompson 01924 515 595
email: johnty99@ntlworld.com or
www.na-bmfa.org
November
at the Garforth Squash & Leisure Centre,
Ninelands Lane, LS25 (off the A63, Leeds- 16 BEFA Technical Workshop 2008 at
Kenilworth School and Sports College,
Selby Road). Saturdays 2.15 to 5.15 pm. 5
Leyes Lane, Kenilworth
badminton court size with high ceiling.
Warwickshire CV8 2DA
Licensed Bar, refreshments available. No
Please note the new location
smoking. Separate slots for Slowfly;
Aerobatic; Scale & SMALL Helicopter
(Sub 150 and equivalent brushless motors
only). Any legal frequency. Proof of BMFA
membership essential. No free flight or IC.
Spectators welcome on the observation
47
E.F.-U.K.
The 23rd
Pillerton Hersey Fly-in
Electric Flight Calendar
If you would like details of your event to appear in these pages please send full details to
the Editor EF-UK, contact details on page 4. Please bear in mind that this magazine is
quarterly so ensure that the details are sent in good time.
For last minute information on events please check out the events list on the BEFA
website www.befa.org.uk. Dates, times and, even locations of events can change at the
last minute. You are strongly advised to check on events with the given contacts before
setting out on your journey to any event.
All BEFA flying events require proof of BMFA (or equivalent) insurance and an ‘A’
Certificate to fly. For fixed wing models, any of the fixed wing ‘A’ certificates are
acceptable. For helicopters, a helicopter ‘A’ certificate is required.
All flying models must have been satisfactorily flown at least twice since build or repair
before flying at a BEFA event.
NO TEST FLIGHTS ON THE DAY
Standing Events
1 Sunday of every month - The Brighouse
Vintage MAC have been using the small
airfield at Tockwith, near Wetherby,
Yorkshire for several years, but have
recently had noise problems. The field is
now all electric & any BMFA Member is
invited to fly there on the 1st Sunday in
each month from 10 - 5pm for a small fee.
Do not be put off by ‘Vintage’ they fly
anything! There is a concrete runway
available and details of the site can be
obtained
Contact: Derek Haviour 01422 204 472
November
3 BMFA Northern Area Indoor RC Flying
membership essential. No free flight or IC.
Spectators welcome on the observation
balcony. Pilots £5.00, Juniors £2.00,
Spectators (on balcony) £1.00. For more
information
Contact: John Thompson 01924 515 595
email: johnty99@ntlworld.com or
www.na-bmfa.org
By Robin Andrew
T
he 23rd Pillerton Hersey fly-in had 44
cars turn up for good weather,
although it got more windy as the
day went on. Bob Mahoney brought his
lovely big 9ft ARONCA C2 and put in two
scale looking flights, so good that he won
the Scale Cup.
Dr Mike Payne arrived with his 6ft scale
Swordfish and flew it as if there was no
wind problem. Eric Sutton flew a Koysho
F16 and new Illusion very well. Josh Speirs
entertained us with his usual good
stunting displays.
There were some lovely cabin jobs
brought by Dick Blenkinsop and Tony
Long, but it was too windy to fly them.
Colin Prior brought his 6ft white Boeing
bipe and an EDF Delta which flew well.
Dave Chinery flew a large biplane with
RAF Roundels on it, and that too went
well. John Davies flew his lovely looking
Spitfire to good effect. The fastest model
of the day was a RAZ FAZ which went
ballistic. I brought my 6ft B24 version
called an ‘ARMARDA Leader’ which is
white all over the wings but has coloured
spots on the fuselage. See photos on
pages 10, 11 - 19.
Altogether a grand day out. Our thanks go
to farmer John Lewthwaite and helpers,
who promises a special DO on the 25th
anniversary.
So see ya all again next year.
Your scribe
Robin Andrew
4 BEFA Technical Workshop at a new
location, the Kenilworth School and Sports
College, Leyes Lane, Kenilworth,
Warwickshire, CV8 2DA. See Page 6,7
Please note the new location
December
1 BMFA Northern Area Indoor RC Flying
at the Garforth Squash & Leisure Centre,
at the Garforth Squash & Leisure Centre,
Ninelands Lane, LS25 (off the A63, LeedsNinelands Lane, LS25 (off the A63, LeedsSelby Road). Saturdays 2.15 to 5.15 pm. 5
Selby Road). Saturdays 2.15 to 5.15 pm. 5
badminton court size with high ceiling.
badminton court size with high ceiling.
Licensed Bar, refreshments available. No
Licensed Bar, refreshments available. No
smoking. Separate slots for Slowfly;
smoking. Separate slots for Slowfly;
Aerobatic; Scale & SMALL Helicopter
Aerobatic; Scale & SMALL Helicopter
(Sub 150 and equivalent brushless motors
(Sub 150 and equivalent brushless motors
only). Any legal frequency. Proof of BMFA
only). Any legal frequency. Proof of BMFA
46
E.F.-U.K.
E.F.-U.K.
11
I weighed the airframe before and
after painting and I had applied a total
of 13.7g (0.48 oz.) of paint to the
FlyCat.
However, I’ve estimated the weight
of the supplied decals at 6.6g
(0.23 oz.). The net weight growth is
therefore only 7.1g (0.25 oz.). I think
that is pretty good considering the
appearance.
The underside of the complete airframe
In the next issue, I’ll complete article
including finishing the FlyCat along with
ground testing figures and a flight review.
Jan Bassett
The fan & duct straped to the mount
12
E.F.-U.K.
The painted FlyCat with decals applied
E.F.-U.K.
45
I spent ages making masks from Frisket
masking film so that the separate colours
could be airbrushed in sequence. The effect
of the mask for the yellow centre on the lower
wing skin is shown below.
Having sprayed the silver, yellow, red, blue
and black paints through the appropriate
masks the painting was complete.
Silver upper wing surface & rear booms
The servo leads were extended and then the
servos were fitted and covered with labels
to give a better surface for the paint to adhere
to. The optional carbon spars were also fitted
and glues in place.
As a compromise I decided that the white
outline of the bulls could be omitted on the
upper wing surface as it wouldn’t be much
lighter than the silver anyway.
Having painted everything, the airframe is
completed by gluing the fuselage to the wing
and then fitting all the remaining equipment.
The decals were printed on a colour laser
printer on to standard labels, cut out and
stuck in place to finish off the paint scheme.
Some artistic licence was necessary due to
the slightly different shape, but I think it
works.
Water based paints were used throughout
after they were tested on a piece of scrap
EPS to ensure they didn’t dissolve the
plastic. Most of the paints were sample pots
from my local DIY store.
The upper wing surface and rear of the tail
booms were sprayed silver to start. For the
other colours masks of some sort would be
required.
The painting of the wing assembly is
complete, just a few decals needed
The yellow centre on the lower wing skin
44
E.F.-U.K.
E.F.-U.K.
13
TheBefore and After sanding
controller in this position I had to extend the
wires from the speed controller to the motor.
I also made sure that there was an air passage
to allow cooling air through and enlarged
the air duct in the bottom of the nose a little.
The next task was to lightly sand the surfaces
of all the moulded EPS components to
remove the small moulding pips from the
surface. The wing edges also need sanding
to remove the raised edge left by the mould
join lines. The mould injection points were
then filled to leave a nice smooth profile as
can be seen above.
The FlyCat was then test fitted together to
ensure it would not need any rework after
painting.
14
E.F.-U.K.
As the FlyCat has a number of similar features
to the de Havilland Sea Vixen I decided that
a scale paint finish would be nicer than
finishing the model with the decals provided.
I hunted around the internet and spotted the
Red Bull Sea Vixen and thought that is
superb, but a lot of work. Finding nothing
else suitable, the Red Bull paint scheme it
was to be.
For ease of painting I decided that the booms
and tailplane would be glued to the wing,
but the fuselage would be left unattached.
The control surfaces would be fitted in place
but only using cardboard hinges as a
temporary attachment; they could be
removed if it was easier to spray something
with them off.
E.F.-U.K.
43
FlyCat by Haoye Model - Part 1
by Jan Bassett
The FlyCat is made by Haoye Model in China
(www.haoyemodel.com) and is sold under a
number of different names by several
suppliers. It is also available for pusher
propeller or Electric Ducted Fan (EDF)
propulsion and with differing amounts of
equipment.
It is supposed to be available moulded from
Expanded Polystyrene (EPS) or from
Expanded Polypropylene (EPP), however,
I’ve never seen the EPP version for sale.
The FlyCat has a wing span of 25.6" (650 mm)
and is 30.2" (767 mm) long when completed.
It has a wing area of 165 sq. in. (10.66 dm²)
and a flying weight of 15.2 oz. (430g).
This weight gives a Wing Cube Loading
(WCL) of 12.3 which is the normal range for
a scale model, pretty low for a small EDF
model. For more on WCL see www.efuk.net/data/wcl.htm
The plane is sold in the UK by Al’s Hobbies
(www.alshobbies.com) as the Ally Cat and
is currently £40 plus P&P for the model, fan
and brushless motor. Al’s Models have their
own set of instructions (on the website)
which make the building much easier for
those with less building experience.
I bought my EDF version from United
Hobbies (www.unitedhobbies.com) with the
brushless motor, fan, speed controller and
battery included in the package for $80
(~£40). The postage was around $40 but the
order did include several other heavy items.
The instructions supplied with the kit were a
single sheet of, poorly copied, paper and
really of little use. Having said that the
model is simple to build and all the important
information can be made out.
The photograph below shows the contents
of the kit. The airframe is constructed from
seven components moulded from EPS; 2
fuselage halves, a canopy, 2 booms, the
tailplane and the wing.
Also included is all the hardware required,
the 56 mm diameter fan with motor preinstalled, a parallel duct extension tube, a
25A speed controller, a 3S 1500 mAh Lithium
Polymer battery pack and a tube of glue and
a motor mounting if the pusher propeller
configuration is to be built.
The fan is held on to the model using a thick
plastic strap, wrapped around the fan and
bolted to a motor plate at the rear of the wing
(photo overleaf). The motor plate for fan
use is a 1/16" (1.6 mm) ply plate. The narrow
ply tongue helps to transfer the thrust to the
model and is fairly lightweight.
In the original design the equipment in
the fuselage is all mounted in the nose
compartment. The receiver is mounted
at the front followed by the speed
controller and finally the battery pack. I
decided that the speed controller should
be between the pack and motor to
minimise the leads lengths. To allow this
I hollowed out a void in the fuselage for
the speed controller, just behind the nose
compartment. Even with the speed
Contents
42
E.F.-U.K.
E.F.-U.K.
15
A Cautionary Tail
I took my Majestic Major to the local flying site,
Well the rain had ceased, the weather started looking really bright.
I checked it out and filled it up, (I flew I/C at the time,)
And to cut a long tale short, took off and watched the ‘Major’ climb.
She looked so very graceful, a relaxing plane to fly,
So much so, that I failed to notice how much time passed by.
The fuel ran out, the engine stopped with loads of height in hand
And I brought her round to bring her in on the landing run I’d
planned.
I called ‘Dead stick’ and my companion kept his model clear.
I continued my descent knowing no-one else was near.
The only other person there was miles away from us,
Walking with his Boxer dog: I could land without due fuss.
As I lost more height he released his dog, he let it off the lead,
And it saw my plane, ran after it, quickly gathering speed.
It was going to be a race to see who reached the model first
For if the Boxer beat me, the model would come off worst!
I steepened up the landing run to get it on the ground
With ‘fido’ close enough behind to catch it with one bound.
The plane swept past and flared to land a dozen yards away.
The dog was going to get there first: Not my lucky day!
I ran across to grab the plane as it came to a halt
To prevent the canine carrying out it’s dastardly assault.
It thundered past and got there first, and now it couldn’t fail!
Ken Leach
16
E.F.-U.K.
E.F.-U.K.
41
and discharge currents with no risk of fire
at all. The metal case also makes them
physically rugged. The bad news is that
they don’t have the energy density of Lipo
and the nominal voltage is somewhat lower
at 3.3V instead of 3.7V.
Have a look at the pictures above. The
A123 pack is 2300mAh and weighs 8
ounces, the 8 cell 2400mAh NiCd pack
weighs 18 ounces. The A123 pack has a
very slightly higher nominal voltage at
9.9V versus the NiCd at 9.6V, in other
words, pretty well equivalent in electrical
terms but 10 ounces lighter. Cell
dimensions are 65mm long, 26mm diameter
and weight 70 grams (about 2.5 ounces)
each.
OK, a Lipo pack would be lighter and
smaller, but…
You can charge the A123s at 5 Amps and
they don’t even get warm. I’m discharging
them at 38 Amps in my Vermont Belle and
they come out of the ‘plane only slightly
warm to the touch. Even the NiCds used to
be almost too hot to hold. The ‘plane now
has almost unlimited vertical performance,
not surprising really, it’s got the same
power and is 10 ounces lighter.
There’s a guy in Italy whose been running
charge/discharge tests on a single cell at
5A and 40A respectively for a thousand
cycles so far and it’s only lost 5% of
capacity.
The bad news is that the charge cut-off
voltage is 3.6V as opposed to 4.2V for
Lipo, so Lipo chargers are a bit too high a
voltage. The good news is that Schulze
have apparently added these cells to their
Chameleon chargers, the bad news is that
you have to send them back to Germany to
be upgraded. The good news is that tests
have been run using the Li-ion setting of
4.1V with no problems, so that’s what I’m
using. So far, so good.
As you may have gathered, I’m pretty
impressed with these cells, I just hope they
get around to producing some smaller
ones for the smaller ’planes. As it is, if
you’re running sub-C NiCd or Nimh cells,
these new cells are certainly worth a look.
Don’t let the smoke out!
The rated discharge is 70 Amps
continuous, 120 Amps peak! I can almost
see the F5B fliers salivating.
You can discharge them down to 2V per
cell with no damage. What this means is
that you don’t need a special ESC to avoid
over-discharge, the low voltage cut-off
that the old NiCd ESCs used is well within
limits. I’ve accidentally run them down to
cut-off twice so far with no ill effect.
40
E.F.-U.K.
E.F.-U.K.
17
for more than a few seconds at a time! On
a GWS 9x5 and 3s Lipo it pulls just over
130 Watts. These two motors neatly show
how kV affects the size of propeller you
can use and that weight is a good indicator
of how much power you can put in.
This motor was just displayed as a 400
Watt motor with no other data at all. I
bought because it was cheap! It weighs
140 grams so should be able to handle
somewhere between 280 and 560 Watts. I
worked out the kV by taking data from
various propellers using a Hyperion
Emeter and putting it into the motor
calculator in Drivecalc, it came up with 743.
Compare this with a similar motor like the
AXI 2820/10 with a kV of 1100 and you can
see that this motor suits either a bigger
propeller than the AXI or more cells. And
so it turned out, I was running it on 5s
Lipos versus the 3s for the AXI on similar
size propellers pulling 410 Watts. The idea
was to cut the current from the Lipos to
give them an easier life, which worked after a fashion. The important point is that
the numbers are right again.
the best part of a year now; a long time I
know, because they weren’t readily
available in this country. They were
originally developed for power tools where
the relative fragility and somewhat
incendiary nature of Lipo cells would have
been a bit of a concern. Early supplies
were available as ten cell packs for US
Milwaukee power tools that cost £150 in
this country. Now they’re available as
single cells or made up packs from
Robotbirds and others. I bought three
cells at the Nationals and have been flying
them as much as I can. So what’s all the
fuss?
The cells were developed at MIT in the US
specifically to address the flammability
issue with normal Lithium ion cells using
something called nano-phosphate Lithium
ion chemistry. They can take high charge
So there you have it, a relatively simple
way to choose a motor (or compare
motors) without getting into all the grief of
meaningless part numbers.
Just work out how many Watts you need,
which will tell how heavy the motor should
be, and figure out a kV suitable for your
application. Go buy a motor!
A123 Lithium Cells
I’ve been keeping an eye on the
development of the A123 Lithium cells for
18
E.F.-U.K.
39
E.F.-U.K.
Now you’ve got a good handle on how
many Watts you need, you can work out a
weight range for the motor you need.
Taking that 400W ‘plane, you’d be looking
for a brushed motor weighing in the 350 to
550 gram range, an outrunner in the 100 t0
200 gram range and an inrunner in the 90 to
160 gram range. The heavier motors would
be working more within their capacity and
have an easier life. Easy eh?
Maybe some examples would help, all
Chinese motors that came with very little
data.
This is one of the so-called bell motors –
called that because the outer can was
originally a bicycle bell! It’s called a BM
2408-21 (whatever that means) and the kV
KV is a little bit more tricky, but you can
cheat a bit. If someone else has built a
‘plane like yours, you can look at the
motor they’ve used and search for a motor
with a similar kV.
You’ll find that, once you know the sort of
weight of motor you’re looking for, that the
range of kVs available is limited, and it just
becomes a case of deciding if you want to
use a big propeller (say for a glider), which
means a lower kV, or, for a smaller propeller,
a higher kV. Extremely high for ducted
fans! Low kV motors can be used with
higher cell counts as well, another factor to
bear in mind.
38
is quoted as 1750. It weighs 46 grams.
Using the 2 to 4 Watt per gram number for
an outrunner, it should be able to handle
92 – 184 Watts. I’m running a GWS 7x6 on
3s Lipo at 160 Watts, which is near the top
of the range for it.
This motor is called a Suppo A 221/13 and
weighs the same as the bell motor, the only
difference is that the kV is 1000. I wanted
to use a bigger propeller in the little 3D
model it’s fitted in to get plenty of static
thrust for hovering – which I still can’t do
E.F.-U.K.
E.F.-U.K.
19
V for Vengeance
(oops! Sorry, I mean Voltage)
By Bob Smith
H
ow’s that for a Freudian slip? As I
started to write this I was reminded of
an occasion when I was due to
receive a prize at school speechday (very rare,
believe me). The prizewinners were given
book tokens and sent out to the local WH
Smith to choose a suitable textbook. I got
diverted into the fiction section and started
to read the Dennis Wheatley novel “V for
Vengeance”. This was a just a few years after
WW2 and I got so interested in the story that
I exchanged the token for this book instead
of the expected text on Geometry. The
Headmaster was much put out by my lack of
academic responsibility but it was too late to
change things so I inadvertently struck the
first of what later became a series of protests
against authority.
Back to voltage then. When we were all
running Nickel based batteries and brushed
motors it was amperage that was king, the
more amps you could pull then the better your
plane flew, or so it seemed at the time. Now
that we are all brushless and into LiPos, the
emphasis has changed to voltage, though in
a more subtle way.
Firstly there is the cell voltage. 3.7 volts per
cell is a big jump from 1.2 volts per cell and we
generally now work with smaller cell numbers
but higher voltages. The second area, and
the one which is the basis for this article, is
the change in cell voltage as we discharge
them. When we used Nickel cells we knew
that they were so robust that we did not need
to worry about voltage levels. The voltages
could be increased to 1.5 volts/cell in fast
charging and down to very low values (0.5
Going through Ken’s data, it turns out that
there is a linear relationship between how
many Watts an electric motor can take and
it’s weight, providing you compare motors
of equal efficiency. I must admit, I was a
little surprised at this, expecting to have to
include surface area, how many cooling
holes it’s got etc., etc. It’s a straight line
with a fair bit of scatter either side, but it’s
close enough to give us a pretty good
guide to the sort of weight we will need.
Ah, you say, what about the efficiency bit?
Well, we know that ferrite brushed motors
are the least efficient, rare earth brushed
motors and outrunners are about in the
middle of the range, and inrunners are the
highest. If I group the weight required into
those categories, the efficiency problem
goes away. One snag with this plan is that
rare earth brushed motors may be efficient,
but they are relatively heavy because of the
brush gear, so they have to be lumped in
with ferrites.
Be aware, with all the assumptions and
gross simplifications, this is never going to
be an accurate way of choosing a motor,
but it will be a way to get a feel for whether
a motor can do the job or not, and help you
to narrow down your choices.
The numbers you need to know are :Brushed motors 0.7-1.2 Watts per gram
Outrunners
2–4
Watts per gram
Inrunners
2.5 - 4.5 Watts per gram
(I’ve used grams for the motor weight,
because that is what most manufacturers
seem to quote.)
20
E.F.-U.K.
Stands back in triumph waiting for the
rapturous applause for this amazing piece
of information that’s never been published
before, only to be met with a blank stare.
(Some recognition would be nice - the odd
Nobel prize wouldn’t go amiss for a start. I
know how Einstein felt when he showed ‘er
indoors E=MC^2 and she just smiled and
said “Yes dear, what do you want for
dinner?”)
OK, so how do you use this astounding
revelation?
The first job with a new ‘plane is to try to
estimate how many Watts you’re going to
need to make it go.
If you come from an oily fan background
then you can say to yourself, what size
engine would I put in this? Then multiply
the displacement of this engine in cubic
inches by a thousand and there you are that’s how many Watts you’ll need as a
minimum. For instance, if you think it needs
a 0.40 glow, then you’ll need at least 400
Watts. (By the way, I invented this rule as
well. Do I get any credit? Do I heck! I
don’t know why I’m surprised, 40 years of
marriage should have taught me how fair
life is.)
Another way is to take the empty weight of
the plane, add about 30% for the electrics
and the radio and use 50 to 80 Watts per
pound for stooge around models, 100 Watts
per pound for good performance, even more
if you’re a hooligan like me.
E.F.-U.K.
37
TLC from your TLO
By Alan Bedingham
O
ne of the things I’m forever ranting
about is the incomprehensible
numbering system most motor
manufacturers use. I know I’m not alone, I
quite often get questions from members
about motors that I’ve never heard of and
there’s very little I can do to help without
more specific data than just the part
number. Ideally, I like to know the motor
constants and it’s weight so that I can stick
it into one of the motor prediction programs
and see what it’ll do. (As an aside, there’s
a rather nice free one available at
www.drivecalc.de that does a good job,
read the instructions though, it’s not that
intuitive to use.) This sort of information is
rarely available, especially for the flood of
cheap Chinese motors that are coming on
the market. With the help of Ken Myers of
the Electric Flyers Only club in Michigan
USA, I think I can see a way forward. What
Ken did was tabulate in a spreadsheet a
huge pile of data for models with their
motors and batteries, which he kindly let me
have a copy of. Going through all this, an
idea began to emerge.
You’ve got a plane and you want to use an
electric motor to power it, but which one?
The first stage is to work out how much
power you need.
The second stage is to work out a set of
numbers for a motor that will do the job,
preferably numbers that practically all the
manufacturers quote.
36
It turns out that you only really need two
numbers, kV (the abbreviation for rpm per
Volt) and the weight of the motor.
Let me explain – kV is important because it
gives you some idea of how fast the motor
wants to run and also how many cells it
wants to see. A high kV (2000-3000) tells
you the motor is meant for a low cell count
and a small propeller. A low kV (400-600)
tells you the motor is designed for either a
very big propeller on a few cells or a more
normal size propeller on a lot of cells. As
you can see, this number is not enough on
it’s own.
This is where the weight comes in. Apart
from a vague feeling that the bigger the
motor, the more power you can put into it,
I’d never really had a clear idea of the
relationship until I started analysing Ken
Myers’ data. Think about it this way, most
of the good motors we use have efficiencies
in the 75% range, which means that 25% of
the power we’re putting in comes out as
heat. This sounds pretty poor until you
realise that your car engine is only around
30% efficient, the other 70% of the energy
you’ve paid good money for is dumped as
heat from the exhaust and the radiator! The
only way the heat generated in an electric
motor can get away is via the mass of metal
that is the motor itself and thence into the
airflow around it. It is pretty obvious that a
big motor can dissipate more heat than a
little motor, but how much?
E.F.-U.K.
volts/cell) both during and at the end of
discharge. We did not realise how lucky we
were with these cells and when LiPos
appeared it took us a while to appreciate that
we had to be much more careful. LiPos have
to be kept within a band of voltage throughout
their usage, nominally 3.0 volts minimum to
4.2 volts maximum, and this is for every
individual cell in the pack, not just the pack
as a whole. If we look at this more closely,
then we are concerned about several separate
stages in our use of the batteries.
Charging LiPos.
This part is the easiest part to control. If you
have a good charger then those clever
electronic/computer engineers have sorted it
all out for us. The algorithms programmed
into the unit means that the charging rate can
be maintained at the recommended 1C over
the first stage until the pack voltage reaches
the product of the cell count and 4.2 volts.
Once this point is reached the charger holds
the voltage constant and allows the current
to fall away until it is down to around 10% of
1C. The problems of ensuring that each cell
follows an identical charge pattern are
covered by the use of a balancer, either builtin to the charger or as a separate unit, and
that, basically, is it for charging.
Discharging LiPos.
Although we sometimes need to discharge
our packs under controlled bench testing
conditions, the vast majority of our
discharges take the form of a flight with a
model. The fact that the load on the pack
can vary during this process is not important
and we can look at the situation as if the
discharge was at constant current. The
voltage is critical in three forms. Firstly as a
result of the magnitude of the load (i.e. of
the current drawn). As this increases the
voltage of the pack and the cells decreases.
The specification of the pack will include a
recommended maximum discharge (e.g. 20C),
but like all specifications, this is not an
optimum value. The pack voltage can easily
be dragged down to below the critical value
at high loads and it follows that they will
perform much better at lower load rates
whichallows the voltage to be maintained at
a higher level.
E.F.-U.K.
21
The second feature affecting voltage is
temperature. As the pack gets hotter the
internal resistance reduces and the voltage
rises. This can be a secondary reaction to
higher current draw as this causes the pack
to heat up and this can show up as discharge
proceeds. The secret is to take advantage of
the effect but not to excess, as the pack will
begin to deteriorate if the temperature gets
too high. If you are not trying for the ultimate
performance then it might be wise to prefer
the safety and longer life of a pack kept cool
throughout the discharge.
The third aspect of voltage to concern us is
the voltage of the cells at the very end of
discharge. In this area, say the last 10% of
the discharge, cell voltages begin to drop
more rapidly and can quickly drop below the
critical value. Since all this is happening
during a flight it is difficult to check but there
are ways. There are a number of “discharge
protection” units (such as the Leton, the
FMA, the Schulze and the Dimension
Engineering units) available, which fit
between the ESC, the receiver, and the pack
balancing lead. The best of these allow you
to set the minimum individual cell voltage so
that when any cell reaches that value the
power supply is reduced or cut-off. This then
prevents any cell damage although it does
not give you information as to which cell (or
cells) is the problem and by how much. What
we need is a protection module which is also
a data logger and records the cell voltage
reduction values for every cell during the
flight. There is a Custom Electronics logger
which records the individual cell voltages
but does not have a safety cut-out function
so we need someone to combine these
features into a single bit of kit.
Voltage Graphs.
Just to help illustrate why voltage readings
are so important to the use of LiPos, I have
drawn some graphs of the critical features. I
hope you will be able to see from these that
it is voltage which counts with LiPo batteries,
and that the well-being of your packs
depends on controlling the voltages of the
cells during both charging and discharging.
To paraphrase it, “look after your volts and
your volts will look after you!”.
All the pieces fluttered down
The view I took was dim!
He said it was my fault
While I was blaming him!
More wasted months of labour
More money down the drain.
Now, where’s the b***** bin bag,
And here we go again.
The wife looks at me sorrowfully:
‘All that work you did,
The patience needed making them
And hell! Four hundred quid!’
She really riled me when she said
‘Why don’t you give up?’ ‘What!
Me give up aeromodelling?
It’s the only pleasure I’ve got!’
Ken Leach
Photo: Keith Day
22
E.F.-U.K.
Sussex Model Flying Club
E.F.-U.K.
35
I flew a couple of circuits
And as I brought it round
Half the tailplane came adrift
And fluttered to the ground!
Immediately I lost control
And panic then took root
As with throttle fully open
The rest just followed suit.
We wandered to the crash site
And it was then I found
The trowel came in handy
To dig the engine from the ground.
The bits were scattered widely
It was really quite a drag
To pick up every fragment
And shove it in the bag.
New-2-U
A brief round-up of new items of interest
by Bob Smith
If you are a manufacturer, importer, or retailer who has something new
you wish to bring to the attention of the readers,
please send details to me at the address given on page 4
The all-new “Smart Guide” series of
brushless speed controllers from Thunder
Power. Available initially in 18A, 25A, and
30A versions.
These controllers utilise “Balanced
Discharge Monitoring & Protection”
(BDMP) technology. This innovative new
system provides real time monitoring of the
discharge voltage of each cell in your lipo
pack. Since each cell is monitored and
protected by the ESC, you can expect an
even longer service life from your packs as
you fly with increased confidence.
During programming the ESC the user
selects the individual cell cut-off voltage at
either 2.75v 3.00v or 3.25v and the controller
will automatically sense the pack voltage by
multiplying the cells it has detected. i.e. if
you set 3.0 volts during programming, and
connect a 3-cell pack, the ESC will sense
Two hundred quid and months of work
And all a total loss!
Forget the work, two hundred quid
Did not amuse the ‘boss.’
I had taken a second plane along
‘Twas a shame to waste the weather:
So my mate and I decided
That we’d try to fly together.
We took off and formated,
The models looked just fine
Until he reversed his turn
And flew his into mine!
34
E.F.-U.K.
The Thunder Power TPE-25SGB3 Smart Guide Controller
E.F.-U.K.
23
there is a 3-cell pack connected, and set its
pack cut-off voltage to 9.0v. If any of the
cell voltages drop below 3.0v during the
discharge the ESC will automatically drop
into BEC.
All “Smart Guide” controllers have heli
governor mode, and a special heli “very
soft” start up mode. The “eZ” programmer
is also available if you wish to program
your controller directly rather than using
the transmitter.
Spec for 25Amp version shown: Model
TPE-25SGB3, Cont. Current 25A, Burst
Current ( >10s) 35A, BEC Mode Linear,
BEC Output 5V/2A, Li-ion Li-poly » 2-3,
NiMH NiCd » 5-12, User Programmable
YES, Balance Discharge Protection YES,
Weight 27g, Size (LxWxH) 45x26x11mm
I drive down to the airfield
To meet up with the boys,
We traipse across to the flight line
Where we play with our toys.
After the flying is over
I head back to the car
Then head for home, which in my case
Really isn’t very far.
I unload all the ‘bits and bobs’
And stow it in the garage.
The wife can read me like a book
After umpteen years of marriage.
‘How did the flying go?’ she asks.
(I’m not a happy bloke!)
It immediately dawns on her
She wished she hadn’t spoke!
The Thunder Power eZ Programmer Card
The Latest style of Schulze Chargers
www.westlondonmodels.com
Again available from West London Models, number of modifications made to improve
these are the latest versions of the welleven further their versatility and reliability.
established and respected range of charge/ There are four models currently available
dischargers from Schulze. Originally
(6.30-5, 6.30-5plus, 7.36-8, and 10.36-8car)
marketed under the “Chameleon” label
with the top-end 20.36-14 expected early
these units have been re-named “New
next year.
Generation”. The styling has been
The outline specification includes charge/
completely remodelled and, although the
discharge of Ni-Cd, Ni-MH, Lead-, Li-Poly,
outstanding qualities of the Chameleon
Li-Ion and Li-FePo4 batteries with
range have been retained, there are a
integrated balancing; a 5V-SIO port for
24
E.F.-U.K.
I’d put a bin bag in the car
In fact I’d taken two
Essential kit for modelers
And I took a trowel too.
‘Well,’ I told her, ‘in the rush
I made a slight mistake.
In loading my big floater,
I thought I heard something break.’
There was no sign of damage
So no reason to despair:
I filled the tank and started up
And it rose into the air.
E.F.-U.K.
33
CellShield is a low voltage cut-off device
which provides cell-by-cell protection for
lithium battery packs. By monitoring each cell
individually, CellShield prevents individual
cell overdischarge due to pack imbalance or
cell variations. It also provides a soft cut-off
when the lowest voltage cell of the pack
reaches the set minimum voltage. The
minimum voltage is adjustable from 2.5v/cell
to 3.5v/cell. This lets you set the proper cutoff voltage for your specific pack. For
example, 8-10C cells typically use a 3.0v/cell
cut-off, while 20C cells work better with a
3.2v/cell cut-off. CellShield’s cut-off voltage
is set with an easy-to-use potentiometer.
There are no programmers to buy or
complicated programming procedures. With
CellShield, you turn the arrow to the cut-off
voltage you want and go fly.
CellShield also features optional thermal
probes, which prevent pack damage due to
overheating. When using the thermal probe,
if the battery temperature rises above 65 ºC,
CellShield will reduce the throttle command
sent to the ESC in an attempt to bring the
battery temperature back down. If the battery
stays above 65 C, CellShield will enter soft
cut-off mode. When using the thermal probe,
CellShield alerts the user to temperature faults
by flashing the red Temp light. The thermal
probes are extremely thin, and can often be
inserted between the innermost cells of the
pack, where pack temperature is highest.
detailed interfacing with a PC: patented
automatic current calculation for Nickel
batteries; dual-language menu: English /
German. Default language English; Software
updates and upgrades will be available on
the Schulze website for downloading; Large
graphic screen with white backlighting and
128 x 64 pixels; Integral ultra-precise Power
Boost balancer; 8 voltage measurement
inputs for monitoring individual cells in a
battery; Incorrect polarity protected power
input and charging outputs.
Bob Smith
At the time of writing there is no UK dealer in
these items but they are available direct by
ordering on the internet.
A DAY IN THE LIFE OF AN ‘AEROMUDDLER’
(But not me of course - Ken Leach)
The phone rings and you pick it up
A voice sounds in your ear:
The winds are light, no rain about,
The sky looks pretty clear.
Front view of the Schulze 7.36-8 New Generation charge/discharger
Do you fancy going flying mate?
I look. The sun is bright
It’s rather cold I’m thinking,
But then again, I might.
I fast charge all the batteries
And assemble all the gear,
I stow the models in the car
And check that it’s all here.
32
E.F.-U.K.
Side view of a Schulze New Generation showing cooling fan
E.F.-U.K.
25
Bantam Mains/12 volt charger and Checkmaster
www.bantamtek.com
The Bantam range of electric flight goods is
starting to become readily available in the
UK under the eStation banner. OverTec and
BRC models stock this brand of increasingly
popular units.
The E-Station BC6.
This is a mains/12 volt DC charger which is
ideal for use in the workshop to charge a set
of LiPo batteries intended to provide a days
flying without field re-charging. It has a
built-in balancer which is a much more
compact arrangement than using a separate
balancer, and it also has specific
programming for lithium iron phosphate cells
such as A123 cells. These are the nanophosphate lithium cells which have slightly
differing specifications to lithium polymer
and lithium ion cells but are by far the safest
version of lithium battery technology to be
available to modellers.
26
The unit has optimized operating software.
When charging or discharging, BC6 has an
‘AUTO’ function that sets the feeding
current or the cell count of Lithium battery
automatically. Especially for Lithium
batteries, it can prevent the over-charging
can lead to an explosion by users fault. Every
program in the unit is controlled with mutual
links and communication for every possible
error so it introduces a maximum safety.
These can be set at users’ option.
The outline specification for this unit is as
follows:- it will operate with 1 to 15 nickel
cells and 1 to 6 lithium cells; it has a maximum
charge current of 5 amps, a maximum
discharge current of 1 amp; it will record data
for up to 5 repeated charge/discharge cycles;
it has a built-in LiPo balancer, a battery
temperature sensor, and a USB computer
interface/software; it is 140 x 130 x 45 mm
and weighs 920 grams; it has an LCD readout screen with 2 lines of 16 characters.
The Bantam eStation BC6 Mains/12 volt DC charge/discharger
E.F.-U.K.
Dimension Engineering Products
www.dimensionengineering.com
This is a range of electronic and electromechanical products for the hobbyist.
Dimension Engineering was founded in
Akron, Ohio in 2004. They aim to sell easy
to use, competitively priced products
without compromising on quality. All of
Dimension Engineering’s products are
designed, assembled, tested and packaged
by them. Their range already includes a
number of items of interest to the electric
flyer, particularly their Liposhield and
Cellshield units.
The Liposhield is a low voltage cut-off
device which enables any ESC to be used
with lithium battery packs. It installs easily
between your receiver and ESC and provides
a reliable 3.0V per cell cut-off to prevent overdischarge damage to your expensive lipo
packs. LipoShield is a soft cut-off, so it is
appropriate for any plane, even 3D types.
The soft cut-off gradually reduces power to
the motor allowing you to make a controlled
landing.
The Dimension Engineering Liposhield and Cellshield units
E.F.-U.K.
31
Tornado Enrichpower NiMH cells and Packs
www.enrichpower.com.cn
One of the sad effects of the surge in the use
of LiPos in electric flight is the relative demise
of NiMH. This is very unfortunate in many
respects as the development of these has
continued at possibly a greater pace than
before and although they will never approach
the energy density of LiPos, they are cheaper,
safer, and much more robust. New
manufacturers have appeared on the scene
(mainly of Chinese origin) and they have
matched (and in some cases exceeded) the
products of the well-established sources.
Enrichpower is one such organisation
(produced actually by Shenzhen Vigor Power
Battery Co., Ltd.) and Overtec have packaged
these under their Tornado Professional label.
The units included here are 2/3 AF size (17
mm diam. X 27 mm long) and have a rated
capacity of 1500 mAh (it was only a few years
back that the famous Sanyo 500AR of the
same size had a capacity of only 500 mAh).
Not only that, but according to the
manufacturers specification this cell can
sustain discharges up to 30 amps. They are
an excellent power source, particularly in
applications which do not demand very high
power outputs or extended duration. Their
application in sports flying is still well
justified and they remain an economic
approach to this area.
The Bantam Checkmaster
This is a multi-tester designed for electric
and general aeromodelling applications in
both workshop and field situations. It has
a wide range of features including:- Precision pulse generation to test servos.
You can test any brand of servo for
displacement, deflection, neutral point, and
bandwidth. It does not need a separate
battery to operate servo (it has an internal
supply). It indicates the servo operating
current continuously and hence allows
you to choose an appropriate RX battery
for your model based on the summation of
all servo current loads.
- Watt meter up to 100A. You can establish
the ideal motor/propeller match for
optimised current. The wattmeter can be
also be operated with the tachometer to
optimise thrust. The unit has automatic
voltage/amp calibration. Supply voltage
does not need calibration, even if the
internal source drops below 4.5V. .
- Propeller tachometer. A precision
tachometer for up to 6 blades and
34000RPM. Up to 10 incremental RPM
values can be stored to the memory.
- Temperature sensor. A solid-state
temperature sensor operated via contact
with the component to be checked.
- RX battery checker/discharger. RX
battery performance can be accurately
checked under load for NiCd 4.8/6.0/9.6V
and Lithium 7.4V with 100 to 1000mAh
current load. After checking, the standing
voltage and the capacity remaining are
A 9.6 volt pack of the Tornado Professional Enrichpower 1500 mAh cells
30
E.F.-U.K.
The Bantam Checkmaster
E.F.-U.K.
27
The Cyclon Plug & Fly Motors
www.cyclonbrushless.com
A new range of outrunner motors from this
French manufacturer designed so that the
motor incorporates the ESC into the same
housing. This is not entirely a new idea as
some of the older brushed motors used it,
but this is a fresh development in
brushless motors. Three sizes are
available, 30, 40 and 50 ratings (300, 400,
and 500 watts nominal), all 44 mm diameter
with weights of 185, 220, and 280 grams
respectively. The Kv values are 1310, 880,
and 680 rpm/volt and the motors can drive
propellers in the 12/13 inch range mounted
on 5 mm shafts.
The controller is mounted onto a plate at
the rear of the housing (the stationary
portion of the motor), which also provides
the motor mounting flange, and the case is
ventilated to ensure that this part of the
combined unit does not overheat. The
advantages of this system are several but
the major features are the performance
matching of the motor and controller, and
the space saving aspect of this
combination. Although the motor is
perhaps 10 mm longer overall you do not
need to find space to fit a normal ESC and
its cables.
A view of the controller position on the Cyclon P&F
The Dualsky Outrunner with combined ESC
www.dualsky.com
A strange coincidence, but at the same time
as the Cyclon motor above becomes
available, so does this unit with the same
principle but at the opposite end of the
motor size range. Intended for park and indoor
flyers, this unit is also a combined outrunner/
ESC based on the established Dualsky XM
2812CA-27 turn outrunner with a 6-amp
controller built into the back. The combined
unit has a Kv of 1780 rpm/volt, uses a 2S
LiPo, and can turn 7.5 to 8.5 inch diameter
propellers.
With a total weight of a minute 28 grams this
tiny motor/ESC will get lost on the front of
many models but is still capable of flying
models up to 200 grams total weight.
Although not yet available at the time of
writing it will certainly be in stock at Als
Models by the time you read this.
A Cyclon Plug and Fly brushless outrunner
28
E.F.-U.K.
The Dualsky combined brushless outrunner and ESC
E.F.-U.K.
29