Prop Sizing Guide

A good guide for selecting the correct prop...



Have you ever built a new plane, or installed a different engine size and were not sure of the correct prop size to use? The following guide lists the correct prop to start with for 2-stroke and 4-stroke engines. It also lists a range of prop sizes you can use depending on engine rpm desired, ground clearance required, and the acceleration or top speed you might like to acheive.

TWO STROKE ENGINES

STARTING PROP

ALTERNNATE PROPELLORS

ENGINE SIZE

6x3

5.25x4, 5.5x4, 6x3.5, 6x4, 7x3

.049

7x4

7x3, 7x4.5, 7x5

.09

8x4

8x5, 8x6, 9x4

.15

9x4

8x5, 8x6, 9x5

.19-.25

9x6

9x7, 9.5x6, 10x5

.20-.30

10x6

9x7, 10x5, 11x4

.35-.36

10x6

9x8, 11x5

.40

10x7

10x6, 11x5, 11x6, 12x4

.45

11x6

10x8, 11x7, 12x4, 12x5

.50

11x7

11x7.5, 11x7.75, 11x8, 12x6

.60-.61

12x6

11x8, 12x8, 13x6, 14x4

.70

13x6

12x8, 14x4, 14x5

.78-.80

14x6

13x8, 15x6, 16x5

.90-.91

16x6

15x8, 18x5

1.08

16x8

16x10, 18x5, 18x6

1.20

18x6

18x8, 20x6

1.50

18x8

18x10, 20x6, 20x8, 22x6

1.80

20x8

18x10, 20x6, 20x10, 22x6

2.00

FOUR STROKE ENGINES

STARTING PROPS

ALTERNATE PROPELLERS

ENGINE SIZE

9x6

9x5, 10x5

.20-.21

11x6

10x6, 10x7, 11x4, 11x5, 11x7, 11x7.5, 12x4, 12x5

.40

11x6

10x6, 10x7, 10x8, 11x7, 11x7.5, 12x4, 12x5, 12x6

.45-.48

12x6

11x7.5, 11x8, 12x8, 13x5, 13x6, 14x5, 14x6

.60-.65

13x6

12x8, 13x8, 14x4, 14x6

.80

14x6

13x6, 14x8, 15x6, 16x6

.90

16x6

14x8, 15x6, 15x8, 16x8, 17x6, 18x5, 18x6

1.20

18x6

15x6, 15x8, 16x8, 18x6, 20x6

1.60

18x10

18x12, 20x8, 20x10

2.40

20x8

18x10, 18x12, 20x10

2.70

20x10

18x12

3.00




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