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 THE FIRST FLIGHT OF YOUR AIRCRAFT

By Chris Heintz

[This article is part o a series! "here aerona#tical en$ineer Chris Heintz

%isc#sses li$ht aircrat %esi$n an% constr#ction&'

(ith the )il% sprin$ "eather #pon #s! it*s ti)e to $et rea%y or that +rst ,i$ht

o yo#r ho)e-#ilt aircrat& The ollo"in$ inor)ation is not crash co#rse on

ho" to -eco)e a prototype test pilot. rather! it*s si)ply instr#ctions on ho"

to peror) that +rst ,i$ht o yo#r aircrat -#ilt ro) plans or a /it&

For )onths yo# ha0e -een har% at "or/ -#il%in$ yo#r aircrat! spen%in$ all on

yo#r ho)e-#ilt aircrat& The ollo"in$ inor)ation is not a crash co#rse on

ho" to -eco)e a prototype test pilot. rather! c#rrent a$ain 1 it*s ti)e to start

$ettin$ rea%y or the +rst ,i$ht o yo#r aircrat&

I yo# eel r#sty! $et so)e %#al! then ,y solo an% re$ain yo#r con+%ence in

an aircrat that*s si)ilar to the one yo#*0e 2#st co)plete%& E0en 3han$ar

,yin$3 can -e #se#l! i yo# can separate the tr#th ro) all the -ra$$in$ an%3-i$ stories&3

O co#rse! yo#r aircrat )#st -e rea%y as "ell! an% this incl#%es4

(ei$ht an% -alance "ithin the %esi$ner*s speci+cations&

See Fi$#re 5

3R#n #p3 o the en$ine as per )an#act#rer*s reco))en%ations& 6This is

especially i)portant "ith the t"o1cycle en$ines that ha0e -eco)e )ore an%

)ore pop#lar recently&7

A chec/ o the po"erplant 6i&e&! en$ine! car-#retor! inta/e an% e8ha#st

)aniol%! re%#ction #nit i applica-le an% propeller7 to 0eriy that it )eets the

)an#act#rer*s static R9:& An easy "ay o chec/in$ the THRUST is to in,ate

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the tires 3har%!3 rest the) on a s)ooth an% ,at s#race 1 ply"oo% "or/s "ell

an% attach a lar$e +sh scale at the aircrat*s tail en%& Start the en$ine! "ar)

it #p! $o #ll throttle an% ha0e a rien%! "itho#t $lasses! rea% the scale& Thr#st

in po#n%s sho#l% -e appro8i)ately o#r ti)es the horsepo"er or a cr#ise

prop! +0e ti)es the horsepo"er or a cli)- prop& Yo# )ay "ant to %o it

se0eral ti)es or -etter acc#racy&

See Fi$#re ; an% <

Re)e)-er! tho#$h! the en$ine coolin$ syste) is not %esi$ne% or in%e+nite#ll throttle on the $ro#n%& =o not e8cee% 5> secon%s #ll open an% allo"

three )in#tes coolin$ at ;?> percent i%le -eore the ne8t test& Also note that

the co"lin$ )#st -e installe% as the -a@in$ only %#cts air past the coolin$

+ns "ith the co"l properly installe%& Yo# can -#rn o#t the aircrat en$ine in

less than 5> secon%s #ll throttle "itho#t a co"l& The co"l is not only an

aesthetic co)ponent -#t also an i)portant part o the coolin$ syste)&

O co#rse! each ti)e the en$ine is r#nnin$ either yo# or a /no"le%$ea-le

pilot )#st -e at the controls& Tie the aircrat %o"n or e8tra preca#tion&

=#rin$ $ro#n% r#n #p o the en$ine! chec/ that no part o the aircrat is

sha/in$ an%or 0i-ratin$ hea0ily 1 chec/ e0ery > rp) ro) i%le to #ll open

an% "atch the tail an% other control s#races as "ell as the -otto) o the

#sela$e&

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It is also 0ital to chec/ that the #el s#pply "ill -e a%e#ate in the )ost

critical con+$#ration 1 at #ll po"er #s#ally in tail lo" attit#%e& The #el

3hea%3! i&e& 1 hei$ht o #el ro) car-#retor to #el tan/ )#st )eet the

)ini)#) le0el or contin#e% operation "ith little )ore than the #n#sa-le #elin the tan/&

At the sa)e ti)e it is i)portant to chec/ the #el #antity $a#$e 6e)pty

e#als "hen en$ine stops r#nnin$ in a-o0e critical attit#%e7 at ;! ;

an% #ll& This is not only i)portant or #el cons#)ption an% ran$e chec/ -#t

also to %etect #ic/ly i s#%%en #n#s#ally hi$h #el cons#)ption %e0elops

6i&e& lea/7&

An%! o co#rse! -y this ti)e yo# either /no" that yo# can easily inspect yo#r

en$ine -eca#se the co"l co)es oD "ith si8 =US asteners or yo# realize

that yo# sho#l% loo/ #n%er the co"l! e0en i it re#ires #nscre"in$

asteners or inspection

 Ta8i Tests

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=o not start ta8i tests #nless the aircrat has ;1;< ho#r #el s#pply an% is

loa%e% 6"ith -allast i re#ire%7 in the )i%1ran$e o its center o $ra0ity

tra0el. it yo# %on*t ollo" these $#i%elines! yo# )ay +n% yo#rsel in the air

-eca#se yo# are not at $ross 6lo"er stall spee%7 an% yo#r error in the

in%icate% air spee% )ay -e si$ni+cant& Re)e)-er! yo# also are in $ro#n%

eDect&

=#rin$ the ta8i r#ns! chec/ the -ra/es! the steerin$ an% $et a)iliar "ith thenoise le0el! seat -elt astenin$ an% release! control position 6car-#retor heat!

#el 0al0e! tri)! )i8t#re! etc&7 an% the i)portant instr#)ents s#ch as air

spee% an% rp)! alti)eter! en$ine te)perat#res an% press#res& (hen yo# %o

ta8i tests at spee%s a-o0e ?> percent o the stall spee% $i0en -y the

%esi$ner! -e prepare% to 6acci%entally7 lit oD& I there is eno#$h r#n"ay let!

throttle -ac/ an% p#t it %o"n a$ain& =o not p#sh it %o"n! tho#$h 1 it*s al"ays

s#ch a sha)e to ha0e to repair a -ran% ne" aircrat

:a/e so)e ;> ta8i r#ns on the r#n"ay to $et the eelin$ o "hen to a-ortta/e oD "ith s#cient r#n"ay to stop "ith )o%erate #se o the -ra/es& This

helps a)iliarize yo# "ith initial acceleration! an% a -it 6only a -it7 "ith ho"

the controls eel 6li$ht! hea0y! sensiti0e! sl#$$ish7& Al"ays tri) at the )i%1

ran$e as yo# are only $#essin$ "here it sho#l% -e set&

O/ay! yo#r en$ine r#ns "ell! -ra/es "or/! instr#)ents see) o/ay! yo#

han%le the aircrat "ith con+%ence on the $ro#n% 6i it*s a tail%ra$$er an% yo#

ha0e little con0entional $ear e8perience that "ill ta/e so)e ti)e $ettin$ #se%

to& A tail%ra$$er is less sta-le on the $ro#n% than a tricycle $ear plane7& It is

0ery i)portant yo# eel co)orta-le an% 3at ho)e3 in the pilot*s seat&

First Fli$ht

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So it is ti)e to $o &&&&

Chec/ once )ore yo#r center o $ra0ity at )i%1ran$e position ro) the #ll

tra0el $i0en -y the %esi$ner& Chec/ yo#r #el #antity! chec/ it physically

"ith yo#r eyes or a %ipstic/! %o not rely on the #el $a#$e #ntil pro0en

relia-le&

O/ay! the aircrat is rea%y! -#t ho" a-o#t yo#

First o all! yo# )#st "ant to %o that +rst ,i$ht 1 %o not let anyone p#sh yo#

into the air! e0en i heshe is a "ell1)eanin$ relati0e or rien%& Secon%! yo#

)#st -e rela8e% 1 yo# )ay chec/ yo#r astrolo$ical si$n or -iorhyth)s i yo#

"ant 1 -#t the i)portant thin$ is yo# si)ply eel this is the %ay An%

%e+nitely not "ith the help o a co#ple o -eers

o"! chec/ the "eather4 There sho#l% -e little or no "in%! $oo% 0isi-ility 6no

haze7 an% at least a 5!>>> oot ceilin$& A0oi% the ti)e aro#n% s#nset i yo#r

acti0e r#n"ay is

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press#re slo"ly to increase the airspee% an% reattach the air ,o" o0er the

"in$& Apply #ll po"er $ently an% cli)- at ;5> percent o yo#r stall spee%&

 Tri) 6this tri) settin$ "ill -e yo#r ta/e oD tri) in this con+$#ration! "ei$ht!

C&G& an% ,aps #p7&

Chec/ the airport 6or are yo# lost -y no"7

:a/e another t"o or three stalls to $et a $oo% a0era$e rea%in$ an% eel

co)orta-le&

o" co)e in or a lan%in$4 Use ;5> percent o stall spee% on -ase an% +nal!

ai) a e" eet a-o0e the r#n"ay entrance an% re%#ce throttle! then spee%

only o0er the r#n"ay an% 2#st hol% her -ac/ #ntil the aircrat settles -y itsel

on the $ro#n% at the stall spee% yo# no" /no" 6%o not 3p#)p3 her %o"n7

(itho#t stoppin$ the en$ine! ta8i -ac/ or another ta/e oD& This ti)e set the

tri) or cli)-! )a/e the ta/e oD rotation at the in%icate% stall spee%!

accelerate to ;5> percent o stall an% let her cli)-! %o"n"in% at 3cr#ise!3

-ase an% +nal at ;5> percent stall as or the +rst lan%in$&

9eror) one or t"o )ore circ#its -eore yo# -rin$ her -ac/ to her tie %o"n&

Correctly %one! the a-o0e e8ercises "ill ta/e ? to M> )in#tes& An% no" yo#

are no lon$er arai% o yo#r aircrat4 Yo# /no" it ,ies an% yo# can han%le it

 Yo#r aircrat "as %esi$ne% an% -#ilt to ,y an% it %oes&

Call the %esi$ner o yo#r aircrat an% share "ith hi) the pleas#re o yo#r +rst

,i$ht 1 -oth yo# as the -#il%er an% he as the %esi$ner %eser0e it&

e8t ti)e yo# ,y! start #sin$ ,aps 6i applica-le7&

e8t )onth "e "ill tal/ so)e )ore a-o#t the testin$ that sho#l% -e

co)plete% %#rin$ those +rst ;? ho#rs o ,yin$ yo#r ne" li$ht plane&

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 The E8peri)ental Aircrat Association has e8cellent reso#rces re$ar%in$ ,i$ht

testin$ yo#r /it aircrat! incl#%in$ the hi$hly reco))en%e% Fli$ht A%0isor

9ro$ra)&

 This article is presente% as part o a series! "here aerona#tical en$ineer Chris

Heintz %isc#sses the technical aspects o his li$ht aircrat %esi$ns in lay)en

ter)s&

 This article "as p#-lishe% in EAA Li$ht 9lane (orl% )a$azine 6:ay ;KNM7&

;KNM! Chris Heintz&

For"ar% ro) EAA Li$ht 9lane (orl% 6?NM74

3Chris Heintz has test ,o"n all o his prototype aircrat to $et the 3-#$s* o#t 1

so that -#il%ers can -#il% a $oo% aircrat "ith con+%ence& Chris* tr#st in

ho)e-#il%ers is sho"n -y the act that he )a%e the +rst ,i$ht o se0eral

plans -#ilt eniths an% o%iacs 65N i his )e)ory ser0es hi) correctly7&

3In the ollo"in$! Chris shares "ith #s so)e o these )ore i)portant points

he chec/s -eore an% %#rin$ that +rst ,i$ht o a plans -#ilt aircrat!1 it*s the)etho% he*s %e0elope% to )a/e that +rst ,i$ht #se#l an% en2oya-le or the

pilot&3

[Bac/' [Chris Heintz =esi$n Colle$e'