How Do Bolts Handle Engine Weight and Turbulence in Flight?

[mb85]

A 1800 kg jet engine is fastened to the fuselage of a passenger jet by just three bolts (this is the usual practice). Assume that each bolt supports one-third of the load. (a) Calculate the force on each bolt as the plane waits in line for clearance to take off. (b) During flight, the plane encounters turbulence, which suddenly imparts an upward vertical acceleration of 2.2 m/s2 to the plane. Calculate the force on each bolt now.

I figured the equation to use for part A would be,
F=m(a+g)
= 1800(9.8+0)
=17640 then x 1/3rd
= 5880 N for each bolt

For part B, same equation with addition of the new acceleration
F=m(g - a)
=1800(9.8 - 2.2)
= 10640 then x 1/3rd
= 3546.7 N

I think I am missing some basic concept or understanding of what i am exactly looking for? and what the equation should actually be.

 

[Andrew Mason]

A 1800 kg jet engine is fastened to the fuselage of a passenger jet by just three bolts (this is the usual practice). Assume that each bolt supports one-third of the load. (a) Calculate the force on each bolt as the plane waits in line for clearance to take off. (b) During flight, the plane encounters turbulence, which suddenly imparts an upward vertical acceleration of 2.2 m/s2 to the plane. Calculate the force on each bolt now.

I think I am missing some basic concept or understanding of what i am exactly looking for? and what the equation should actually be.

Your answer to a) is correct. In b) your approach is correct but: ask yourself what the direction of the force on the engine is if the wings are forced upward with an acceleration of 2.2 m/sec^2. Does that add or reduce tensile forces on the bolts?

AM

 

[kyle8921]

Your calculations for both parts A and B are correct. However, there are a few things to consider in regards to the concept and equation used.

Firstly, the equation you used, F = m(a+g), represents the total force on the engine due to its weight (mg) and the acceleration (a) experienced by the jet. In part A, the plane is at rest so the acceleration is 0, and in part B, the plane experiences an upward acceleration of 2.2 m/s^2. So, the equation you used is appropriate for both parts.

However, it is important to note that the force on each bolt is not equal to the total force on the engine. This is because the bolts are not evenly distributing the weight of the engine. In reality, the weight of the engine is distributed unevenly among the bolts, with the bolt closest to the center of gravity bearing the most weight. This is why the assumption of each bolt supporting one-third of the load is just a rough estimate and not an exact representation of the actual forces on each bolt.

Additionally, in part B, the sudden upward acceleration experienced by the plane could also cause additional forces on the bolts due to the change in direction and the inertial forces acting on the engine. These forces would need to be taken into consideration for a more accurate calculation of the forces on each bolt.

In summary, your calculations are correct based on the given information and the equation used. However, in a real-world scenario, there are additional factors that would need to be considered for a more accurate calculation of the forces on each bolt.