﻿SOARING 
  FLIGHT 
  KLEMPEEER 
  235 
  

  

  Much 
  ingenuity 
  has 
  been 
  displayed 
  in 
  facilitating 
  disassembling 
  

   and 
  road 
  transport. 
  This 
  feature 
  was 
  a 
  great 
  asset 
  for 
  the 
  con- 
  

   testants 
  after 
  long-distance 
  glides 
  in 
  the 
  hilly 
  country. 
  

  

  In 
  the 
  glider 
  field 
  the 
  question 
  of 
  monoplane 
  or 
  biplanes 
  has 
  

   been 
  rather 
  decidedly 
  settled 
  in 
  favor 
  of 
  the 
  monoplane. 
  Extremely 
  

   large 
  aspect 
  ratio 
  ( 
  = 
  span: 
  wing 
  chord) 
  became 
  some 
  sort 
  of 
  a 
  

   dogma. 
  The 
  production 
  of 
  lift 
  by 
  wings 
  is 
  inseparable 
  from 
  evok- 
  

   ing 
  induced 
  drag, 
  proportional 
  to 
  the 
  square 
  of 
  the 
  load 
  per 
  wing 
  

   span. 
  In 
  the 
  glider, 
  all 
  protruding 
  structures 
  being 
  carefully 
  

   avoided 
  to 
  a 
  much 
  greater 
  extent 
  than 
  is 
  possible 
  on 
  a 
  motor 
  air- 
  

   plane, 
  the 
  more 
  the 
  ideal 
  of 
  the 
  nothing-but-wing 
  machine 
  is 
  ap- 
  

   proached, 
  the 
  more 
  the 
  induced 
  drag 
  becomes 
  decisive 
  for 
  efficiency. 
  

   Theoretically 
  this 
  was 
  quite 
  well 
  understood. 
  It 
  was 
  the 
  merit 
  of 
  

   the 
  gliders 
  to 
  have 
  practically 
  proved 
  the 
  correctness 
  of 
  the 
  theory 
  

   of 
  aspect 
  ratio 
  and 
  induced 
  drag 
  in 
  full 
  size. 
  Wing 
  spans 
  con- 
  

   sequently 
  grew 
  wider 
  and 
  wider 
  and 
  wings 
  spanning 
  twelve 
  times 
  

   their 
  chord 
  became 
  quite 
  common. 
  A 
  gliding 
  angle 
  of 
  1 
  : 
  20 
  was 
  

   reached 
  with 
  them. 
  Of 
  course, 
  in 
  order 
  to 
  accomplish 
  this 
  it 
  is 
  

   essential 
  also 
  to 
  avoid 
  struts 
  and 
  external 
  bracing, 
  with 
  their 
  para- 
  

   site 
  resistance. 
  Structurally, 
  it 
  is 
  quite 
  a 
  task 
  to 
  build 
  a 
  light 
  wing 
  

   spanning 
  30 
  feet 
  from 
  root 
  to 
  tip 
  on 
  the 
  cantilever 
  principle, 
  having 
  

   only 
  5-foot 
  base 
  depth 
  or 
  less, 
  at 
  the 
  root. 
  Responsible 
  designers 
  

   of 
  the 
  old 
  school 
  were 
  quite 
  hesitating 
  to 
  risk 
  something 
  like 
  that, 
  

   so 
  it 
  took 
  the 
  boldness 
  of 
  college 
  students 
  to 
  demonstrate 
  that 
  it 
  

   can 
  be 
  done. 
  The 
  idea 
  of 
  the 
  large 
  wing 
  span 
  was 
  in 
  the 
  course 
  of 
  

   events 
  perhaps 
  exaggerated 
  and 
  overemphasized 
  by 
  amateurs. 
  A 
  

   few 
  accidents 
  due 
  to 
  wings 
  failing 
  by 
  torsion 
  or 
  vibration 
  happened, 
  

   although 
  none 
  of 
  serious 
  consequences 
  to 
  the 
  pilots. 
  They 
  had 
  the 
  

   welcome 
  effect 
  of 
  stimulating 
  research 
  on 
  wing 
  flutter, 
  which 
  since 
  

   then 
  has 
  greatly 
  increased 
  knowledge 
  for 
  its 
  prediction 
  and 
  avoid- 
  

   ance. 
  

  

  The 
  tapering 
  of 
  wings 
  toward 
  the 
  tips 
  has 
  been 
  demonstrated 
  to 
  

   contribute 
  enough 
  to 
  structural 
  and 
  aerodynamic 
  efficiency 
  to 
  justify 
  

   the 
  manufacturing 
  complication. 
  The 
  gliders 
  have 
  done 
  much 
  to 
  

   demonstrate 
  the 
  merits 
  of 
  the 
  thick 
  and 
  semithick 
  wing 
  sections, 
  

   and 
  the 
  advantages 
  of 
  well-rounded 
  leading 
  edges 
  for 
  a 
  wide 
  useful 
  

   range 
  of 
  angles 
  of 
  attack, 
  whereas 
  the 
  particular 
  merits 
  of 
  one 
  or 
  

   another 
  special 
  wing 
  section 
  are 
  often 
  overemphasized. 
  

  

  Nowhere 
  can 
  the 
  suppression 
  of 
  parasite 
  resistance 
  be 
  carried 
  to 
  

   such 
  a 
  perfection 
  as 
  in 
  the 
  modern 
  glider. 
  Some 
  of 
  them 
  resemble 
  

   a 
  bird 
  in 
  a 
  striking 
  manner. 
  There 
  is 
  nothing 
  but 
  a 
  wing, 
  a 
  tail, 
  

   and 
  a 
  stream-lined 
  body, 
  just 
  large 
  enough 
  to 
  tightly 
  house 
  the 
  pilot. 
  

   Every 
  aviator 
  will 
  agree 
  that 
  the 
  field 
  of 
  vision 
  from 
  a 
  glider's 
  cock- 
  

   pit 
  is 
  perfect, 
  incomparably 
  better 
  than 
  from 
  that 
  of 
  any 
  regular 
  

  

  