Choose The Right Propeller For Your Engine
By Chris Hinds
 

While all engines produce power the Propeller is essential to transmit this power. A more efficient propeller will transmit more power to the air. In the UK the most commonly available propellers for I/C engines are:

  • Master Airscrew
  • Bolly
  • Kyosho
  • Graupner
  • APC
  • Precedent (Smart & Airflow)
  • Menz 'S' and 'Ultra'
  • Mjenlik

Of these propellers Menz 'S' and Precedent's 'Smart' range are suitable for large engines, these are wooden propellers so tend to break more easily than composite propellers. Mjenlik propellers are also suited to large models and are Carbon Fibre propellers. APC propellers are composite propellers and are excellent for most uses, they are not robust enough for beginners however. Graupner and Kyosho propellers are also composite propellers and are well suited to beginners, as a matter of preference I prefer a Graupner propeller. Kyosho props are a mildly quieter design than Graupner however. Master Airscrew props are noisy, inefficient propellers and their only redeeming feature is their strength against ground impacts - only buy if there is nothing else.

A table of my suggested propeller sizes follows.  It would be fair to say that my recommended props are often much larger than those typically used in the USA but this helps significantly with noise reduction and therefore I will go with a larger prop.  The engines will not bog down with these props, they just won't quite develop all the power they could.  Though to be fair we do overpower anyway.  Prop sizes are only slightly above US recommendations.  If you field is noise sensitive (as many are) then head for one of the large sizes.

Engine Size
Ideal Prop Size
Propeller Size Range
Engine Type
Ideal RPM Range
0.10
7x4
7x4~6, 8x4
2-Stroke Glow
14000~16000rpm
0.15
8x4
7x5~6, 8x4~6
2-Stroke Glow
14000~16000rpm
0.25
9x5
9x4~6, 10x4~5
2-Stroke Glow
12000~15000rpm
0.32-0.36
10x5
9x6~8, 10x5~6, 11x4~5
2-Stroke Glow
12000~15000rpm
0.40
11x5
10x6~8, 11x5~7, 12x5~6
2-Stroke Glow
11000~12000rpm
0.46
11x6
10x7~9, 11x6~8, 12x5~7
2-Stroke Glow
10000~12000rpm
0.53
11x7
10x8~10, 11x7~9, 12x6~8
2-Stroke Glow
10000~11000rpm
0.61
13x6
12x8~10, 13x6~7, 14x5~6
2-Stroke Glow
9500~11000rpm
0.75
13x7
12x9~11, 13x7~8, 14x6~7
2-Stroke Glow
9500~10500rpm
0.91-1.08
14x6
13x10~11, 14x6~8, 15x6~8
2-Stroke Glow
9000~10000rpm
1.20-1.35
16x8
15x8~10, 16x8~10, 17x8
2-Stroke Glow
8500~9500rpm
1.40-1.80
18x8
17x8~10, 18x8~10, 20x6~8
2-Stroke Glow
8000~9000rpm
2.10
20x10
20x10, 22x8
2-Stroke Glow
8000~8500rpm
 
Engine Size
Ideal Prop Size
Propeller Size Range
Engine Type
Ideal RPM Range
0.26-0.30
10x6
10x5~7, 11x4~5
4-Stroke Glow
10000~11000rpm
0.40-0.45
11x6
11x6~7, 12x5~6
4-Stroke Glow
10000~11000rpm
0.48-0.56
11x7
11x7~8, 12x6~7, 13x5~6
4-Stroke Glow
10000~11000rpm
0.63-0.72
12x7
12x7~9, 13x6~7
4-Stroke Glow
10000~11000rpm
0.80-0.91
14x7
13x8~11, 14x7~9, 15x5~7
4-Stroke Glow
10000~11000rpm
1.00-1.20*
14x8
14x7~8, 15x6~10, 16x6~8
4-Stroke Glow
9000~10000rpm
1.40-1.50**
16x8
16x8~12, 17x8~10, 18x6
4-Stroke Glow
8500~9500rpm
1.80-2.00
17x8
16x10~12, 17x8~10, 18x8
4-Stroke Glow
8000~9500rpm
2.40
20x8
18x10~12, 20x6~8
4-Stroke Glow
7500~8500rpm
2.70
20x10
20x8~12, 21x8~10
4-Stroke Glow
7500~8500rpm
3.00-3.20
21x10
20x10~12, 21x8~10, 22x8
4-Stroke Glow
7500~8500rpm
 
Engine Size
Ideal Prop Size
Propeller Size Range
Engine Type
Ideal RPM Range
1.40-1.80
16x8
16x8~10, 17x8~10, 18x8
Gas
8500~9500rpm
40cc
20x8
18x10~12, 19x10, 20x8~10
Gas
6500~7800rpm
45cc
20x10
20x10~12, 21x8~10, 22x8
Gas
6000~7500rpm
50cc
21x10
20x12, 21x10~12, 22x8~10
Gas
6000~7200rpm
60cc
22x10
22x10~12, 24x8~10, 26x8
Gas
6000~7200rpm
75cc
24x10
24x12, 26x10~12
Gas
6000~6800rpm
100cc
26x10
26x10~12, 28x10
Gas
6000~6500rpm
150cc
32x12
30x10~12, 32x10~12
Gas
5500~6000rpm
200cc
34x11
32x12~14, 34x10~12, 36x10
Gas
5000~6000rpm

*The Yamada FZ120 is very powerful so a 16x8 is advised as a minimum, 15x10 being an alternative.

**The Yamada FZ140 Limited is more powerful than a Saito 180 so use the 1.80-2.00 prop sizes as a guide.

The figures are merely estimates - do not take them as gospel they are merely a rough guide.  As aside notes:

  1. The 3W and Desert Aircraft petrol engines are very powerful for their size and larger props should be used such as a 28x10 on a 100cc Twin from these manufacturers.

  2. I generally like to prop the engine in the RPM ranges above, to develop power without excessive noise levels.  In order to meet the UK limits a sensible mounting system (I like the Dubro Mounts) and an APC or similar propeller should be used, provided the manufacturer's silencer is adequate.  Of the engines I have come across, O.S., Irvine and MDS Silencers are adequate without extra silencing fitted.  The O.S. silencers are the best of the standard silencers though.