Engineering, 20.09.2019 22:30 Turtlelover05

Acurrent problem in the u. s. army is the neck/shoulder fatigue experienced by helicopter pilots. to be able to fly missions at night, the pilots wear night vision goggles, which are attached to the front of the helmet. unfortunately, these are fairly heavy, causing a large downward torque of the head, which must be counteracted by the neck muscles, which then fatigue. to alleviate this problem, many pilots have started attaching random lead weights to the back of the helmet. find the appropriate weight that would best balance the head and minimize neck fatigue. assumptions: a) cg of goggles is 8 inches in front of neck pivot point, b) goggles weigh 2 lbs., c) max volitional neck torque is 480 in lbs., d) cg of lead weight is 5 inches behind neck pivot point, e) bare helmet weighs 4 lbs., and f) cg of helmet is 0.5 inches in front of neck pivot.

Answers: 2

Show answers

Another question on Engineering

Engineering, 03.07.2019 14:10

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Answers: 3

Answer

Engineering, 04.07.2019 18:10

Afour cylinder four-stroke in-line engine has a stroke of 160mm, connecting rod length of 150mm, a reciprocating mass of 3kg and its firing order is 1-3-4-2. the spacing between cylinders is 100mm. i. show that the engine is in balance with regard to the primary inertia forces and primary 3. a and secondary inertia couples. li determine the out of balance secondary inertia force ii. propose ways of balancing this out of balance force and discuss the challenges that will arise

Answers: 3

Answer

Engineering, 04.07.2019 18:10

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk

Answers: 1

Answer

Engineering, 04.07.2019 18:10

Aturning operation is performed with following conditions: rake angle of 12°, a feed of 0.35 mm/rev, and a depth of cut of 1.1 mm. the work piece is aluminum alloy 6061 with t6 heat treatment (a16061-t6). the resultant chip thickness was measured to be 1.0 mm. estimate the cutting force, fc. use shear stress of 207 mpa and coefficient of friction on the tool face of 0.6.

Answers: 1

Answer

You know the right answer?

Acurrent problem in the u. s. army is the neck/shoulder fatigue experienced by helicopter pilots. to...

Questions