au khi hoàn thành chương này, sinh viên sẽ xác định độ cao, mật độ các yếu tố ảnh hưởng đến nó, và độ cao mật độ có hiệu lực có hiệu suất máy bay. Mục tiêu cho phép 1,1 1,2 1,3 1,4 Nhớ lại những khí chính của không khí. Nhớ lại những ảnh hưởng của áp suất, nhiệt độ và độ ẩm vào mật độ của không khí. Xác định độ cao áp lực. | CHAPTER ONE THE ATMOSPHERE TERMINAL OBJECTIVE Upon completion of this chapter the student will define density altitude the factors affecting it and the effect density altitude has on aircraft performance. ENABLING OBJECTIVES Recall the main gases of the air. Recall the effect of pressure temperature and humidity on the density of the air. Define pressure altitude. Define density altitude. Recall the effect of temperature and humidity on density altitude. Compute the density altitude using a density altitude chart. Compute the density altitude using the rule of thumb formula. Recall the relationship between helicopter performance and density altitude. THE ATMOSPHERE 1-1 CHAPTER 1 HELICOPTER AERODYNAMICS WORKBOOK THE ATMOSPHERE ATMOSPHERIC PROPERTIES Helicopter aerodynamics is the branch of physics dealing with the forces and pressures exerted by air in motion. The atmosphere the mass of air which completely envelops the earth is composed of varying and nonvarying constituents. The nonvarying constituents include oxygen 21 and nitrogen 78 . The varying constituents include CO2 argon hydrogen helium neon krypton and water vapor which will vary from negligible amounts to approximately 4 by volume 100 relative humidity . Air is a fluid and is affected by changes in temperature pressure and humidity. ATMOSPHERIC PRESSURE Atmospheric pressure at any altitude is a result of the downward pressure exerted from the mass of air above that altitude. The air at the surface of the earth will be under a greater pressure than air further up a given column of air. Pressure altitude is defined as an altitude corresponding to a particular static air pressure in the standard atmosphere. The standard atmosphere corresponds to the temperature and pressure of the standard day 15 C or 10MB psi at sea level . Therefore the pressure altitude of a given static air pressure corresponds to the actual altitude only in the rare case where .
