Avicraft Ltd

Propeller Selection Chart

To select a propeller for your engine, Look at the cu-in value of the engine and cross reference the possible prop sizes, the left hand props are smaller, higher revving props where as the right hand props are larger and slower revving. If you have the instructions for your engine there should be information in there that will help with the selection.

The propeller numbers represent the diameter vs the attack of the prop so a 7 x 3 prop is 7 inches diameter and would theoretically move 3 inches forward in one revolution.

Larger props tend to be used for 3D and aerobatic flying as they give the ability to act as a break whereas the smaller props tend to be used in speed applications - the ideal prop for normal club flying would therfore probably be somewhere in the middle.
As an example, for a . 2 stroke engine on a trainer or 2nd model, we would normaly recommend a 11 x 6 or 11 x 7.
As a word of caution - not all props are created equal !, the same size prop from different manufacturers can act differently in use so there is always an element or trial and error.

If your unsure which would best suit your application, please call the shop.

TWO-STROKE PROP CHART
Engine (cu. in.) vs Propeller selection

0.049	5.25 x 4	5.5 x 4	6 x 3.5	6 x 4	7 x 3
0.09	7 x 3	7 x 4.5	7 x 5
0.15	8 x 5	8 x 6	9 x 4
.19 - .25	8 x 5	8 x 6	9 x 5
.29 - .30	9 x 7	9.5 x 6	10 x 5
.35 - .36	9 x 7	10 x 5	11 x 4
0.4	9 x 8	11 x 5
0.46	10 x 6	10 x 7	11 x 5	11 x 6	11 x 7	12 x 4
0.5	10 x 7	10 x 8	11 x 7	12 x 4	12 x 5
.60 - .61	11 x 7.5	11 x 7.75	11 x 8	12 x 6
0.7	11 x 8	12 x 8	13 x 6	14 x 4
0.9 - .91	13 x 8	15 x 6	16 x 5
1.08	15 x 8	18 x 5
1.2	16 x 10	18 x 5	18 x 6
1.5	18 x 8	20 x 6
1.8	18 x 10	20 x 6	20 x 8	22 x 6
FOUR-STROKE PROP CHART
.20 - .21	9 x 5	10 x 5
0.4	10 x 6	10 x 7	11 x 4	11 x 5	11 x 7	11 x 7.5	12 x 4	12 x5
.45 - .48	10 x 6	10 x 7	10 x 8	11 x 7	11 x 7.5	12 x 4	12 x 5	12 x 6
.60 - .65	11 x 7.5	11 x 7.75	11 x 8	12 x 8	13 x 5	13 x 6	14 x 5	14x6
0.8	12 x 8	13 x 8	14 x 4	14 x 6
0.9	13 x 6	14 x 8	15 x 6	16 x 6
1.2	14 x 8	15 x 6	15 x 8	16 x 8	17 x 6	18 x 5	18 x 6
1.6	15 x 6	15 x 8	16 x 8	18 x 6	18 x 8	20 x 6
2.4	18 x 12	20 x 8	20 x 10
2.7	18 x 10	18 x 12	20 x 10
3.0	18 x 12	20 x 10

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