Design Materials & CAD CAM
The Design of a Power Screw Flap Actuator
Design brief
In this brief you are asked to design a flap actuator for a light aircraft using the application of
power screws, shafts, gears, etc. The power screw needs to be run using an electromotor and
gearbox which should be designed as a part of this course work. Applying sound engineering
principles, you are required to propose an effective means of applying torque from an
electromotor to the power screw and also hold the load (flap) securely at any position within
the specified stroke.
Power Screws are used for providing linear motion in a smooth uniform manner. They are linear
actuators that transform rotary motion into linear motion. Power screws are generally based on
Acme, Square, and Buttress threads. Efficiencies of between 30% and 70% are obtained with
conventional power screws.
COURSEWORK BRIEF FOR UFMFD8-30-2: 2019/ 2020 ACADEMICSESSION Page 4 of 10
CW1: Design Embodiment
You are required to propose one configuration for your actuator, and to evaluate its viability by
appropriate calculations, and then development into a detailed proposal (this development work
is the CAD task).
Technical specifications for the actuator:
1. Max force (W): 7000 Newton
2. Power screw/actuator linear velocity under load : 10.0 mm/s
3. Reliability 95%
4. Factor of safety: 4-6
5. The actuator should be as compact as possible.
6. Maximum extension of actuator: 200 mm
7. Life: 8 years; assume the motor works 10 hours per day at top speed
8. Maximum temperature: 50° C
9. The power screw used for this application should be self-locking.
10. The gearbox can accommodate any type of Bevel, Spur or Helical gears but not Worm gears.
11. Screw actuator and gears should be made from aircraft grade steel.
12. Maximum size of large gear 150mm
