﻿AEEONAUTIC 
  RESEARCH. 
  

  

  By 
  Joseph 
  S. 
  Ames, 
  Ph. 
  D., 
  LL. 
  D. 
  

  

  Professor 
  of 
  Physics, 
  The 
  Johns 
  Hopkins 
  University, 
  Baltimore, 
  Maryland; 
  

   Chairman, 
  Executive 
  Committee, 
  National 
  Advisory 
  Committee 
  for 
  Aero- 
  

   nautics. 
  

  

  [With 
  5 
  plates.] 
  

  

  Progress 
  in 
  the 
  navigation 
  of 
  the 
  air 
  is 
  being 
  made 
  constantly 
  

   along 
  two 
  quite 
  distinct 
  and 
  independent 
  lines; 
  one 
  is 
  the 
  art 
  of 
  

   flying 
  and 
  the 
  other 
  is 
  the 
  science 
  of 
  flight. 
  To 
  this 
  last 
  is 
  given 
  

   the 
  name 
  aeronautics 
  ; 
  and 
  by 
  an 
  aeronautical 
  investigation 
  is 
  meant 
  

   a 
  research 
  which 
  has 
  a 
  direct 
  bearing 
  upon 
  our 
  knowledge 
  of 
  the 
  

   properties 
  of 
  solid 
  bodies 
  immersed 
  in 
  a 
  stream 
  of 
  air 
  or 
  moving 
  

   through 
  the 
  air. 
  We 
  wish 
  to 
  know 
  the 
  forces 
  and 
  moments 
  acting 
  

   upon 
  such 
  solid 
  bodies; 
  how 
  these 
  vary 
  with 
  the 
  shape 
  and 
  charac- 
  

   teristics 
  of 
  the 
  bodies, 
  and 
  how 
  they 
  are 
  affected 
  if 
  the 
  velocity 
  of 
  

   the 
  air 
  is 
  changed. 
  Another 
  important 
  inquiry 
  refers 
  to 
  the 
  sta- 
  

   bility 
  of 
  the 
  solid 
  body 
  when 
  in 
  flight; 
  if 
  the 
  attitude 
  of 
  the 
  body 
  

   is 
  changed 
  by 
  some 
  gust 
  or 
  otherwise, 
  does 
  it 
  tend 
  to 
  return 
  to 
  

   its 
  previous 
  attitude, 
  or 
  on 
  the 
  contrary 
  does 
  it 
  continue 
  to 
  depart 
  

   more 
  and 
  more 
  from 
  its 
  original 
  attitude? 
  The 
  question 
  is 
  like 
  

   that 
  referring 
  to 
  a 
  body 
  balanced 
  on 
  a 
  table. 
  If 
  it 
  is 
  pushed 
  slightly, 
  

   will 
  it 
  simply 
  oscillate 
  to 
  and 
  fro, 
  or 
  will 
  it 
  turn 
  over? 
  These 
  

   matters 
  and 
  similar 
  ones 
  make 
  up 
  the 
  subject 
  of 
  aeronautics; 
  and 
  

   in 
  order 
  to 
  investigate 
  them 
  the 
  same 
  methods 
  must 
  be 
  applied 
  as 
  

   in 
  any 
  department 
  of 
  physics. 
  

  

  Experiments 
  must 
  be 
  performed; 
  a 
  theory 
  is 
  evolved; 
  deductions 
  

   are 
  made 
  from 
  the 
  theory 
  and 
  tested 
  by 
  experiment; 
  the 
  theory 
  

   is 
  modified 
  and 
  improved, 
  etc. 
  During 
  all 
  the 
  process 
  knowledge 
  

   is 
  being 
  gained, 
  and 
  the 
  facts 
  being 
  made 
  known 
  help 
  the 
  designer 
  

   of 
  aircraft 
  to 
  make 
  improvements 
  in 
  speed, 
  in 
  carrying 
  power, 
  in 
  

   safety, 
  in 
  stability. 
  

  

  One 
  most 
  important 
  fact 
  should 
  be 
  emphasized, 
  and 
  this 
  is 
  that 
  with- 
  

   out 
  the 
  series 
  of 
  scientific 
  studies 
  just 
  outlined 
  not 
  only 
  would 
  flight 
  

   itself 
  have 
  been 
  impossible, 
  but 
  also 
  all 
  progress 
  in 
  the 
  art 
  would 
  

  

  1 
  Presented 
  at 
  the 
  meeting 
  of 
  the 
  Section 
  of 
  Physics 
  and 
  Chemistry 
  of 
  the 
  Franklin 
  

   Institute 
  held 
  Thursday, 
  Oct. 
  6, 
  1921. 
  Reprinted 
  by 
  permission 
  from 
  the 
  Journal 
  of 
  the 
  

   Franklin 
  Institute, 
  January, 
  1922. 
  

  

  167 
  

  

  