Starting Propellor sizes are mid range pitch props that should fly just about any plane designed for that size engine. Use these first as in most cases they will be close to being the correct size. Then use trial and error to try and fne tune the maximum performance from your model by trying to alternate props. If none work better stick with the recommended starting prop.

Four Stroke Engines

Alternate Propellors Starting Prop. Engine Size
9x5, 10x5 9x6 .20 - .21
10x6, 10x7,11x5, 11x7, 11x7.5, 12x4, 12x5 11x6 .40
10x6, 10x6, 10x8, 11x7, 11x7.5, 12x4, 12x5 11x6 .45 - .48
11x7, 11x7.5, 11x8, 12x8, 13x5, 13x6, 14x5,  14x6 12x6 .60 - .65
12x8, 13x8, 14x4, 14x6 13x6 .80
13x6, 14x8, 15x6, 16x8, 17x6, 18x5, 18x6 14x6 .90
14x6, 15x86, 15x8, 16x8, 17x6, 18x5, 18x6 16x6 1.20
15x6, 15x8, 16x8, 18x6, 20x6 18x6 1.60
18x12, 20x8, 20x10 18x10 2.40
18x10, 18x12, 20x10 20x8 2.70
18x12, 20x10 20x10 3.00

Two - Stroke Engines

Alternate Propellors Starting Prop. Engine Size
5.25x4, 5,.5x4, 6x3.5, 6x4, 7x3 6x3 .049
7x3, 7x4.5, 7x5 7x4 .09
8x5, 8x6, 9x4 8x4 .15
8x5, 8x6, 9x5 9x4 .19 - .25
9x7, 9.5x6, 10x5 9x6 .20 - .30
9x7, 10x5, 11x4 10x6 .35 - .36
9x8, 11x5 10x6 .40
10x6, 11x5, 11x6, 12x4 10x7 .45
10x8, 11x7, 12x4, 12x5 11x6 .50
11x7.5, 11x7.75, 11x8, 12x6 11x7 .60 - .61
11x8, 12x8, 13x6, 14x4 12x6 .70
12x8, 14x4, 14x5 13x6 .78 - .80
13x8, 15x6, 16x5 14x6 .90 -.91
15x8, 18x5 16x6 1.08
16x10, 18x5, 18x6 16x8 1.20
18x8, 20x6 18x6 1.50
18x10, 20x6, 20x10, 22x6 18x8 1.80
18x10, 20x6, 20x10, 22x6 20x8 2,00
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