Which Prop Should I Use?

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All engines produce power. The prop (or to give it its proper name... propeller) is a device that converts this power into forward thrust.
ALL PROPS ARE NOT EQUAL. A more efficient prop will transmit more power, which gives more thrust and produce less noise.

Below is the most common model aircraft prop for use on IC engines.

APC are the most common propellers for sport and "pattern" flying. They are made out of a composite material and are excellent for general use. Graupner are also composite propellers and are well suited to beginners as they are more resistant to the odd "nose over". The square ended type also tend to be on the noisy side. The standard Master Airscrew props are noisy and inefficient propellers, their only redeeming features are their strength and their cost. Master Airscrew produce a good quality, medium noise and low cost prop range called the "Scimitar" range.

What prop should I use? I hear you ask

Below you will find a table for common engine sizes & types. For each engine size there is a "preferred size" this is listed as a good starting point for your model to pass the 82dB(A) limit.

These figures are gestimates - they are intended only as a rough guide

Prop Selection Charts

2 Stroke Engines:

ENGINE SIZE PREFERRED SIZE ALTERNATE SIZE
.049 6x4 5¼x4,  5½x4,  6x3½,  6x3,  7x3
.09 7x5 8x4½,  7x4½,  7x5
.15 8x5 8x4,  8x6,  9x4,  9x5
.19 - .25 8x6 8x5,  9x5,  9x6,  10x5,  11x4
.29 - .30 10x6 10x5,  10x6,  10x7,  10½x6,  11x6
.35 - .40 11x6 10x6,  10x7,  10x8,  11x6,  11x7,  11x8
.45 11x8 11x6,  11x7,  11x8,  12x6,  12x7,  12x8
.50 - .53 12x6 11x8,  11x9,  11x10,  12x5,  12x6,  12x8
.60 - .61 13x11 14x8,  14x10,  15x10,  15x12
.70 14x10 13x11,  14x12,  15x10,  15x12,  16x8,  16x10
.78 - .80 14x10 14x10,  14x12,  15x10,  15x12,  16x8,  16x10
.90 - .91 15x10 15x8,  15x12,  16x9, 16x10,  16x12
1.20 16x10 16x10,  18x5,  18x6
1.50 16x12 15x12,  18x10,  20x8
1.80 16x12 15x13,  18x12,  20x8


4 Stroke Engines:

ENGINE SIZE PREFERRED SIZE ALTERNATE SIZE
.45 - .48 12x6 11½x6,  12½x6,  12x7,  12x8
.60 - .65 12x6 11x7½,  11x7¾,  11x8,  12x8,  13x5,  13x6
.70 12x7 12x6,  12x8,  12x9,  13x6,  13x7,
.80 13x7 12x8,  12x10,  13x8,  13x10,  14x6,  14x8
.90 13x11 12x12,  13x12,  14x10,  16x8,  16x10
1.08 16x6 15x8,  18x5
1.20 16x8 15x10,  18x7,  18x8
1.60 16x10 15x10,  15x12,  16x8,  16x12,  18x8,  18x10
2.40 20x10 18x12,  20x8,  20x12
2.70 22x10 18x12,  20x8,  20x10
3.00 20x10 18x12,  20x12,  22x10

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