rr&{w
F-ulL
iloD
BUZZARII
Build this A/O class
glider by Brian
Faulknerand have
some fun with hi-start
The A,zO class glider
ln l99l John Wingateproposeda new sma)l
ficld glkl('r competition,it was acceptedby the
TimDcrlcy committee and a club contcst was
arransctl for the 8th of December.This fun
cventwas inspiredby the Thermic 36 designed
by John Zaic, published in 'Model gl;der
design" by l-rank Zaic. The rules limited the
total projcctcd wing and tail area to 139.5sq
ins with a minimunr weight of 2 1/2 ounces.
l-auncheswcrr to bc made using a 'Histafl'
with 50 ft of thrrad an(l 10 feet of rubber. ltabv
12
Aero Modeller
Baby Buzzard
is an A/O class
glider for use
with hi-start
and ideal for
club
competitions.
It is apable of
a good
perfotmance
so fit a
dethermaliser!
Buzzardwas basedon my A/1 and A/2 gliclers
but with a lower aspectratio lo givc a centre
scctionchordof4" with taperedtips to 3" chord.
A tailplane arca of 24.75 sq ins was chosen
whichis 22%ofthe wingprojected
arcaof 122.5
scl.ins. I.or stabilitythe tail momcnt was 17.25"
giving a lusclagelength oi 26.375rr.
With thrs
gconctry the centre of gravity was predicted
to bc al 55%ol the wing chord fronr thc lcading
cdgc.'l hcsc basicproportjonshavebccn found
satishctory on my A/1 and A/2 gliders
but I wonderedif a small 30rrglidcr
would bc slablc.
climbedto the top of the line, thcn turned right
as thc auto nidder slackenedoff, and thc tow
ring rclcascdleavingthe glided tcrcirclc away.
AJter scvcral more flights acljusiingthc tail
packing and rudder setting to givo a straighl
tow and floating circular glide, tsaby Lluzzar<l
was drifting to the linits of the flying field as
thc wind slrength increased.Sundaythc 8th of
Decomberwasidealfor flying, early frost,clear
bluc sky, a light breezeand by mid claya weak
sun gave sofic light lift. After a few test flights
Baby Buzzardwaslaunchedon the first contest
flighl ancl I was surpised when it caught a
thermal anclclriftcd,gainingheight, acrossthe
trials
park. SinceI had not fitlcd a dethernuliserfuse
I thought it was on a onc way trip to Valhalla.
n ., Lolcl(luuJy day wilh light drizzh
I-uckily Baby Buzzard escapedlhe Thennal
t . l t : t l l ti rn 'l Jj l trl , - .t r't r .il iall- lsclor ].
God ancl lancledaller 3 nlinutcs 11 seconcls.
.' Sometestswith thc'Histart'hadshownon
l' 1' a smallgliderthat l/16r' sq rubbcrwasthe
Fu hcr flights were madc with a D/T fitted,
but by late afternoonthe thermal activily had
-r'idcals;re. 1/8" taking thc glider up too fast
clicd down.
l-. 3:ausingil_1()unhook prematurcly.aid stall
I found thc A/O glider contest a rcal lun
down,landing
usuallyon its nose.R.H.War'ring
givcs this advicc in the Harboroughbook
event, rcquiring a dilft]rent technique to thc
nbr:,ininr
'ModelOlidcrs'Dublished
in the early 1940s. rowlillprlid, r If 1uu \ave ,lilficLrlry
help to launch your glider, or at the field your
With a small inilial strctch ofthe'Histarl', Ilaby
friendsarc too busy llying, lhis Histart'is idcal.
Iluzzardclimbcdvcry fastto halJthelinc lcngth
An extra bonus is thc cnjoyment of watching
then returneclto earth with the line still
your glider climbing on lhe line. It also avoicls
aftachecl.'ll1c
faulty60.{,C(} waslo blamc.More
u r: glrr ur. r'ld 'Ll o l-. n',. e r nr l t he uinlrunning with your hcad down looking out for
rabbitholes.
incidenceincreased.The next launch was
bettcr,bul the towring was rcluctantto release.
Construction
h thc R.lL Warring book, thc A.P.S.gliders
had
Aeolus
and
olhcrs
Sone notes on the constructionmay be
Aegeus, l.cander,
hcll-rIul.Builrl the wings and tail first to allow
torvhooksinclincd at 50 to 60 dcgrccs to the
horizontal axis ol the glider. I have always any warpsto be coniected.-lle original had all
wurrd,r,"lrl t\, rnwrin g* u ulLl . lit , of in a
surfacesflat except the left outef wing pancl
prolraclcd hand low. Howevcr the rcason for
whcre 1/16"washoutwasbuill in (Place1/16"
packing under the left trailing cdgc at lhc lip
these anglc hooks becameclear to nrc, these
gliders were probablylaunchedby 'Histart' or
when building) I1 is suggestedlhat thc spar
slots are cut out aftcr assembly,marked from
Catapultlaunch as it was known in 1942whcn
a steel straight edgc or stretchedcotton. 'Ihe
thc S.M.A.E.rules allowed 75 feet of thread
tip spars are set back lrom the centre spruce
and 25 feet of rubber. Somc long flights were
spars and well ccmcntcd together to grve a
madeusing this launch.for examplea British
rccord of over 20 minutes flown by Mr
strongjoint- I'ick finn slraightwood for the LE
and TE to achicvc a war? free wing and tail.
Chasteneuf.
Choosestiff quartcr grained sheetfor the ribs.
liol1u ately I hacla pair of plier-sin my bag
Cover with light gradc tissue and be sure to
a rrJ. lu' . \ 11I b e| rhc lu \ hu ol'lu lhe J r apcin
stick the tissue down well to the undersideof
sketch 2. This field modification cured the
problemand on lhe next launch Baby Buzzard Lheribs. I have found that thinncd PVA which
October1992
glue is suitablc.Obtain a light hollow GRI'
(fibreglass)or carbon fibrc tapcredrod as sold
for HL gliders. If you arc a rcal do it yourself
modellerbuild one from sprucc.This is placcd
Ilal on the plan then or thc parts51, 52, S:J,54
and FB cut out and locatcd.llpoxy lB l{J the
(lRP boom.Cut to sizc thc 3/1ij" x 1/8" an.l
cementin placelhcsc upright rncmbefsto form
the spine.Remove{rom thc planand building
board then check thc spinc for slraighln{'ss.
Cut out and cernentthe 1/4" rnediumbalsa
sidc nrembersto each side of the spinc. Lul
out and ccmcntin placethe l/16" shecl half
formcrs. Build, fil, cover and dope the fin and
rudder. Bcnd, solder and fit the swinging
towhook, and thc 18 SWG brass pivot tube
which is fittcd, cpoxi.d an.l bounclto a spruce
l/8' sq x 3/4" long closs pkrcewhich is c'ln)xid
to the Llndcrsilc ol thc wing platformWPI and
WI'2. Make sure thc towhook will swing lr-eely
without friction. Now asscnblc th( w;ng and
lailto balancethe glicler.Aclcllcad to the ballast
box to achievethe correct balanccat 55%wrl
thc nosc block in place and the 1/16r srdc
Dieceslemporarily pinned in placc a'rd aftcr
thc 1/4' side menrbers have becn carvcd to
tapertowardsF1. It is advisableat this slajlc to
fit Icss than the lull amount of lead since thc
finalasscmbly,covedngand dopingcoukl makc
the gliclcr nosc hcavy.For this reasorlI set the
balanceat 60%but forgotlo makc a finalbalance
check when complctcd. 'fhc cxtra wcight
amountingto a 2p coin was cut lrom ]cad and
epoxied under the nosc. Aftcr comltcting the
balancingepory the lcad into thc ballastbox,
then cementthe 1/16 shectsidesto thc shapcd
1/,1" SM membors.Thc lusclageca then be
sandedto a streanlincd shapc and thc cabin
added.Finish with sandingsealcr until thc
surfacc is smooth and cover in lightweight
modcl span,dope,then adcl2 coats of banana
orl,
T h e T i m p e r l e y g l i d e r c l a s s A/O i s
intcndcd to be about half the size of the
A / I g l i d e r t o r e d u c e t h e c h a n ce s o f
conti Lralflights oul of small flying fields
and annoying farmers yet provide an
interesting contest wh;ch is pure fun. (iood
flying.