AERO3460 Tutorial FAQs by Zi Wang

What is fore-and-aft load?

Zi_AERO — 2024-02-27 02:58:35 UTC

The fore-and-aft load is force acting along the x-direction of the aircraft. This will happen if the aircraft is accelerating or decelerating.

You don't need to consider both vertical and fore-aft loads together. Treat the two types of loads individually.

What if I did my working in MatLab? Do my calculations need to be in the logbook?

2024-02-27 03:19:57 UTC

Short answer: Yes

Long answer: Your code needs to be verified by hand calculations so you'll still need to take some calculations down. Also in terms of marking, the tutors only check the logbook so some evidence of working needs to be in there.

How many group members in each group?

2024-02-27 03:39:21 UTC

Max 8 per group.

How to model the beam self weight as a distributed load?

2024-02-27 04:40:21 UTC

The beam self weight is = Density of the material X cross section of the beam X length of the beam.

Assuming the density of the beam is uniform, then each slice of the beam weighs Density X cross section area per length.

At this step you don't know the cross section area because you haven't chosen the tube dimensions. You have 2 options:

Keep the cross section area as a variable in the equation. So the reaction loads are expressed as a function of the cross section area.
Choose a tube dimension and work through the steps. This is risky because you may need to change the dimensions later. If you do this in Excel or MATLAB you can automate this process to avoid recalculating everything when you choose a different tube.

Do we need to consider the drag and lift on the beam?

2024-02-27 04:41:01 UTC

No. Neglect any aerodynamic effect on the beam, struts and camera.

In the assignment sheet, it says that the mass of the camera is 140lbs. Is this meant to be the force of the camera, not the mass since mass is in slugs?

2024-02-28 05:24:50 UTC

1 pound mass exerts 1 pound force due to gravity on Earth.

Is there a specific format for the Logbook?

2024-02-29 03:16:42 UTC

There is no specific format. Date the pages and make sure the pages are neat and legible.

Streamlined tube data sheet units

2024-03-05 04:09:34 UTC

Equiv. Round O.D. = equivalent round tube outer diameter in inches

Wall Dec. I = wall thickness in decimal inches

Gage = a wonderful imperial system way to measure diameter

Area is cross section area in square inches, calculated based on the equivalent round tube.

Wt. per ft. = pound per foot, the streamlined tube is heavier than the equivalent round tube per foot

Is Euler buckling the critical failure mode for the main beam?

2024-03-05 04:11:49 UTC

Maybe. The Euler buckling critical load only consists of pure compression load, the compressive stress caused by bending moment should not be included.

When calculating the main beam stress due to bending moment, which y and I should I use?

2024-03-05 04:37:39 UTC

Use the equivalent round tube properties for all your calculations. y is the radius of the round tube diameter, I is the round tube 2nd moment of area.

Yuchen told me my load factors are wrong, which part did I go wrong?

2024-03-07 03:56:36 UTC

Check FAR 23.335(a)(3). "V_c need not be more than 0.9 V_H at sea level."

You can find the definition for V_H in Chapter 1 of CFR 14.

How to predict the worst case loads, little bit confused about that

2024-03-12 00:59:23 UTC

What views do we need to do for the CAD drawings?

2024-03-12 05:52:51 UTC

Can we argue for other design considerations when choosing our strut and or beam sections? Like I might choose a larger one to make it easier to fit a lug in there for example.

2024-03-14 10:52:18 UTC

No. Keeping the MoS between 0.05 and 1 takes the highest priority.

Do we only have to consider the critical FAR 23 load cases while calculating the forces and moments acting on the leg and the resulting internal stresses? Or do we consider all 7 cases?

2024-04-03 10:36:14 UTC

You need to consider all 7 cases, but you will notice some of the cases yield much smaller stresses in the landing gear, and two of the cases yield identical landing forces. To simplify our analysis, only consider the cases that yield the highest stresses. That means there are four cases (highest vertical load, highest drag load, highest +ve side load and highest -ve side load).

What do we need to include in the report?

2024-04-11 04:31:00 UTC

Please follow the formatting requirements outlined in the lectures (title page, TOC, drawings, MoS table etc). For the proofs calculation, you need to include FAR 23 load cases calculation; landing gear analysis (MoS calculation for each failure mode under its critical load case = 4 sets of calculation); bolt connection analysis (MoS calculation for each failure mode under its critical load case = 2 sets of calculation); and landing gear vertical deflection.

MoS: The lecture notes said that we need to keep our MoS > 0.15. Like the last time, do we have a maximum value for MoS as well? Or just keeping it above 0.15 is our main and only priority?

2024-04-11 11:41:29 UTC

The maximum MoS for the critical failure mode should be 1.

Vertical Deflection - Is there a maximum value for this? Or any document we can refer to for determining the acceptable value?

2024-04-13 10:26:50 UTC

The maximum value is the propeller tip ground clearance, which is the distance between the ground and the lowest point of the propeller when the Jabiru is parked on level ground. You can check the technical drawings for dimensions. This clearance is more than 10 inches, and you shouldn't expect a deflection more than 3 inches if your design is reasonable.

Critical Failure Mode - Is limit compression the critical failure mode for the leg?

2024-04-13 10:36:26 UTC

This depends on your SID and material choice. For most students I have checked, tension ultimate is the critical failure mode.