Master Airscrew (Windsor Propeller) MR Series 12x4.5 Propeller
Series: Master Airscrew (Windsor Propeller) Propellers for drones
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The MR 12x4.5 is a two-blade propeller of the MR series from Master Airscrew (Windsor Propeller, USA) made of glass-fibre-reinforced composite for mid-sized multicopters. The designation gives diameter and pitch: 12 in, 4.5 in. It is offered as a set of one right- and one left-rotating propeller.
The diameter is 12 in, and 304.8 is given as the figure in millimetres. At a good third of the diameter the 4.5 in pitch is flat and laid out for hovering and efficiency at low rotational speed. Two blades keep efficiency higher than a multi-blade layout. The weight is 21.5 g, the bore 6 mm, and the hub is 8 mm thick. The propeller does not fold. Adapter rings for fitting the bore to the motor shaft have to be sourced separately.
The legal framework belongs to the aircraft: multicopters with 12 in propellers fall, depending on equipment, into classes C1 to C3, and the effort grows with the class. C1 and C2 may fly in subcategory A1 or A2, a C2 aircraft keeping 30 m from uninvolved people. From 250 g take-off mass operator registration is mandatory; classes C1 to C3 require direct remote ID.
When buying, the bore counts: 6 mm does not fit every motor shaft, and without an adapter ring the propeller suits only shafts of that size. Glass-fibre-reinforced composite is tough and tolerates ground contact forgivingly. Check blade tips and leading edges for nicks and the hub around the bore for cracks. Because imbalance loads motor bearings and sensors, the set is replaced together.
Technical data
Other data
| Blade count | 2correct |
|---|---|
| Diameter (inches) | 12correct |
| Diameter (mm) | 304.8correct |
| Folding | nocorrect |
| Hub bore (mm) | 6correct |
| Material | Glasfaserverstaerkter Verbundwerkstoffcorrect |
| Pitch (inches) | 4.5correct |
| Weight (g) | 21.5correct |
What to check before buying
- Check the hour meter against the service records — a replaced instrument is the most common gap.
- Compare the data plate and chassis number with the papers.
- Ask about parts availability for this build year — the running costs hang on it.
A general list for this type of machine — no substitute for an inspection or an appraiser.
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