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The image on the right shows a series of windscreens on an aeroplane - Leaving Cert DCG - Question C-3 - 2021
Question C-3
The image on the right shows a series of windscreens on an aeroplane. Fig. C-3 shows the plan and elevation of a set of similar windscreens on a model aeroplane. A... show full transcript
Worked Solution & Example Answer:The image on the right shows a series of windscreens on an aeroplane - Leaving Cert DCG - Question C-3 - 2021
Step 1
Draw the plan and elevation of the surfaces A, B, C, and D.
Answer
To draw the plan and elevation of the surfaces A, B, C, and D, start by interpreting the provided figures in Fig. C-3.
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Plan view:
- Begin with the base line XY.
- Mark points A, B, and C in their respective positions based on the dimensions provided in the plan.
- Decide on the orientation of each surface, ensuring the angles make sense considering the aerial perspective.
- Connect the dots to outline the shapes of surfaces A, B, C, and D.
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Elevation view:
- Using the same line XY, plot points A, B, C, and D.
- Maintain the heights of each surface as specified, drawing the vertical lines from the points created in the plan view.
- Ensure all dimensions and angles are accurate for a precise representation.
Step 2
Determine the dihedral angle between the surfaces A and B.
Answer
To determine the dihedral angle between surfaces A and B:
- Identify the line of intersection between A and B using the projections along XY.
- Draw a horizontal line parallel to XY from point B.
- Establish a new line Y1 perpendicular to the line of intersection.
- Calculate the angle formed between these two lines using trigonometric functions or geometric methods: angle = an^{-1} rac{h}{b} where h is the vertical height and b is the horizontal distance between surfaces.
Step 3
Draw a one-piece surface development of the surfaces C and D.
Answer
To draw a one-piece surface development of surfaces C and D:
- Begin with surface C:
- Visualize its features and dimensions to develop its true shape.
- Transition to surface D:
- Make sure to connect and align it appropriately to ensure it rests flat in the development.
- Use drafting tools to ensure lines are straight and dimensions are accurate,
- Each edge should match with the joint between C and D.
Step 4
Draw the projections of the line PQ.
Answer
To draw the projections of line PQ:
- Assess the inclination of line PQ at 45° to the horizontal plane:
- Use a protractor to ensure accurate projection.
- Determine the correct orientation of line PQ in the plan. This requires understanding how the angle affects where the line will meet the surfaces in plan view.
- Project PQ onto both the horizontal and vertical planes, ensuring that the lengths correspond to the inclination. The projections are represented as dashed lines to indicate they are not visible in this face.