Prop Chart For 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
18x10,20x6,20x8,22x6 18x8 1.80
18x10,20x6,20x10,22x6 20x8 2.00

Prop Chart For Four - Stroke Engines

Alternate Propellers Starting Prop Engine Size
9x5,10x5 9x6 .20 - .21
10x6,10x7,11x4,11x5.11x7,11x7.5,12x4,12x5 11x6 .40
10x6,10x7,10x8,11x7,11x7.5,12x4,12x5,12x6 11x6 .45 - .48
11x7.5,11x7.75,11x8,12x8,13x5,13x6,14x5,14x6 12x6 .60 - .65
12x8,13x8,14x4,14x6 13x6 .80
13x6,14x8,15x6,16x6 14x6 .90
14x8,15x6,15x8,16x8,17x6,18x5,18x6 16x6 1.20
15x6,15x8,16x8,18x6,18x8,20x6 18x6 1.60
18x12,20x8,20x10 18x10 2.40
18x10,18x12,20x10 20x8 2.70
18x12,20x10 20x10 3.00


Propeller Safety


Install the prop with the curved side of the blade facing forward and tighten the prop nut or bolt with the proper size wrench.

Recheck the tightness of the nut or bolt often, especially on wood props which tend to compress and loosen more often.

When starting the engine, keep spectators at least 20 feet clear of the model and out of the path of the propeller.

Keep hands away from the prop as much as possible. Use a chicken stick or and electic starter.

Keep face and body out of prop arc as engine is started and run.

Make all adjustments from behind the prop except on pusher prop installations.

Never throw anything into the prop to stop the engine. Use a kill switch or pinch off the engine's fuel supply.

Discard any prop with nicks, scratches, splits, cracks or any other sign of damage. Never attempt to repair, alter or bend a prop.

Don't run an engine in areas of loose gravel or sand for the prop can throw such material into your face and eyes. It's not a bad idea to wear eye protection.

Keep loose clothing, shirt sleeves, and other such items away from the prop and avoid carrying objects that can fall into the prop such as pens, screwdrivers, etc.

Be sure to keep the glow driver wire out of the prop path.

If a spinner is used, be certain that it's edges are not in contact with the propeller blades.