402 Introduction to the Study of Science 



navigation by Lilienthal? 12. Describe the experiments of Hiram 

 Maxim. 13. Why is it not practicable for men to attempt flight with 

 flapping wings ? 14. (a) Give an account of the work of Professor Lang- 

 ley. (6) What principles of aircraft did he discover? 15. Give 

 an account of the progress in aerial navigation made by the Wright 

 brothers. 16. What are some of the records made by airmen? What 

 unusual feats? What do these show as to the control of aircraft? 



17. In what respect does a flying kite resemble an airplane in 

 action? In what respects does it differ? 18. (a) Why does a kite 

 fly? (6) What is meant by the lifting force and the drifting force? 

 (c) From what are the two forces derived? (d) How is drifting pre- 

 vented? 19. What is the importance of surface friction in kite and 

 airplane? 20. What is the form of a vane? In the airplane how 

 is the form important? 21. (a) Explain how equilibrium is main- 

 tained in an airplane. (6) What automatic stabilizers are used? 



22. What difficult conditions does the pilot find in the atmosphere? 



23. In what way is the airplane dependent upon its motor? 



24. (a) Why are size and weight of motor important? (6) What 

 improvements in motors have recently been made? 



SUGGESTIVE QUESTIONS 



1. What aircraft have you seen? Of what type was each? What 

 speed did it make? What length of flight? 2. What would have to 

 be done to make possible a safe and comfortable ascent to altitudes 

 above seven miles? 3. (a) Would it be possible to make a voyage 

 to the moon in an airship ? (6) What conditions of pressure, density, 

 and temperature would be encountered? 4. What attempts have 

 been made to cross the Atlantic in airships? What difficulties would 

 be encountered in such a trip? 5. What advantages do you imagine 

 the use of aircraft would give in Arctic exploration? 6. In what 

 ways could air navigation be of use in our country ? What advantages 

 would it have between New York and Chicago? Los Angeles and 

 New Orleans? 



