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Four stroke engines
four cylinder FF-320 four stroke engine by www.osengines.com
Four cylinder engines are the most fuel efficient internal combustion engines. They however have lower vibration and noise levels than the two stroke engines, but have a higher vibration level than a Wankel engine. They also have a lower power-to-weight ratio than a two stroke engine of comparable power output.
ENYA R.155.4C engine from http://www.modelflight.com.au/enya_engines/enya_r155.htm
|
engine |
capacity in cc |
weight in kg |
power output in kWatts |
kW / kg |
J/ccfam |
|
120FS |
19.93 |
0.910 |
1.566 at 11,250 rpm |
1.721 |
0.838 |
|
R.155.4C |
25.42 |
0.960 |
1.86 at 11,250 rpm |
1.937 |
0.780 |
Notes:
- All Enya engines use " glow fuel" : methanol + 5 to 15 % nitromethane + 16% minimum synthetic castor oil lubricant.
- J/ccfam = energy in Joules per cc of fuel-air mixture
- J/ccfam = ( power_in_watts x 60 x 2 ) / (capacity_in_cc x rpm ) = measure of energy efficiency
The Kavan engine: photograph from www.mecoa.com
- Engine capacity = 50 cc
- weight = 2.6 kg for spark ignition version
- power output at 9,200 rpm = 3.28 kWatts , where the fuel consumption was 25 cc per minute.
- power-to-weight ratio = 1.261 kW / kg
- fuel efficiency = 0.856 Joules / cc_fuel_air_mixture
O.S. Engines FS-70 Ultimate high performance, four stroke, engine with a fuel pump.
Photograph from http://www.osengines.com/engines/osmg0875.html
O.S. Engines FT-300 two cylinder engine from www.osengines.com
|
engine |
cylinders |
capacity in cc |
weight in kg |
power output in kWatts |
kW / kg |
J/ccfam |
|
FS-70 Ultimate |
1 |
11.45 |
0.502 |
0.894 at 11,000 rpm |
1.781 |
0.852 |
|
FS-91 S II |
1 |
15 |
0.649 |
1.193 at 11,000 rpm |
1.838 |
0.868 |
|
FS-120S III |
1 |
20 |
0.921 |
1.56 at 12,000 rpm |
1.694 |
0.76 |
|
FT-160 |
2 |
26.5 |
1.1 |
1.49 at 10,000 rpm |
1.354 |
0.675 |
|
FS-200U |
1 |
32.4 |
0.83 |
2.16 at 9,000 rpm |
2.605 |
0.890 |
|
FT-300 |
2 |
49 |
1.828 |
3.0 at 7,000 rpm |
1.641 |
1.050 |
|
FF-300 radial |
5 |
49.7 |
2.673 |
3.0 at 8,000 rpm |
1.122 |
0.905 |
|
FF-320 |
4 |
53.2 |
2.19 |
3.06 at 8,000 rpm |
1.37 |
0.846 |
Notes:
- All O.S. engines use " glow fuel" : methanol + 5 to 15 % nitromethane + 16% minimum synthetic castor oil lubricant.
- J/ccfam = energy in Joules per cc of fuel-air mixture
- J/ccfam = ( power_in_watts x 60 x 2 ) / (capacity_in_cc x rpm ) = measure of energy efficiency
The O.S. Engines FF-300 radial engine from http://www.osengines.com/engines/osmg1300.html
The O.S. Engines FF-320 " flat four" from http://www.osengines.com/engines/osmg1320.html
- from http://www.rotax.com/en/
|
Performance of the four stroke, four cylinder, Rotax 914 F D.C.D.I UAV Engine |
||
|
power |
84.5 kW |
@ 5,500 rpm |
|
maximum RPM |
5,800 |
rpm |
|
displacement |
1211.2 |
cc |
|
generator performance |
250 Watt DC |
@ 5,500 rpm |
|
voltage |
13.5 |
V |
|
fuel usage at 5,400 RPM |
20 kg/hr (25 L / hr) 237 g / kWatt / hour |
AVGAS 100 LL |
|
engine weight |
70 |
kg |
|
weight of optional extras |
6.7 |
kg |
|
power-to-weight ratio |
1.1 |
kW / kg |
|
engine efficiency |
1.55 |
J / ccfam |
This large engine is included to give a data point for a high capacity engine. The Rotax engine has been used in the Predator and other UAVs.
|
SAITO single cylinder engines |
The SAITO 180 engine.
Photograph from http://www.horizonhobby.com/Products/Default.aspx?ProdID=SAIE180
|
Saito Engine |
Capacity |
Weight |
Power |
Power-to-Weight |
min rpm |
max rpm |
fuel efficiency |
|
cc |
kg |
kWatts |
kWatts/kg |
|
|
J/ccfam |
|
|
FA-45S |
7.50 |
0.440 |
0.522 |
1.186 |
2,000 |
12,000 |
0.696 |
|
FA-50 |
8.20 |
0.435 |
0.634 |
1.457 |
2,000 |
12,000 |
0.773 |
|
FA-56 |
9.20 |
0.410 |
0.671 |
1.637 |
2,000 |
12,000 |
0.729 |
|
FA-56F |
9.20 |
0.410 |
0.671 |
1.637 |
2,000 |
12,000 |
0.729 |
|
FA-62a |
10.24 |
0.469 |
0.746 |
1.590 |
2,000 |
12,000 |
0.728 |
|
FA-65 |
10.60 |
0.550 |
0.708 |
1.288 |
2,000 |
12,000 |
0.668 |
|
FA-72 |
11.80 |
0.470 |
0.895 |
1.904 |
2,000 |
12,000 |
0.758 |
|
FA-80 |
13.10 |
0.540 |
0.969 |
1.795 |
2,000 |
12,000 |
0.740 |
|
FA-82a |
13.80 |
0.453 |
1.119 |
2.469 |
2,000 |
12,000 |
0.811 |
|
FA-91S |
15.00 |
0.555 |
1.193 |
2.150 |
2,000 |
11,000 |
0.868 |
|
FA-100 |
17.10 |
0.551 |
1.342 |
2.436 |
2,000 |
11,000 |
0.856 |
|
FA-120S |
20.00 |
0.900 |
1.641 |
1.823 |
1,900 |
10,500 |
0.937 |
|
FA-125a |
20.52 |
0.700 |
1.641 |
2.344 |
1,800 |
10,500 |
0.914 |
|
FA-150 |
25.00 |
0.852 |
1.864 |
2.188 |
2,000 |
10,500 |
0.852 |
|
FA-180 |
29.10 |
0.881 |
2.088 |
2.370 |
2,000 |
10,000 |
0.861 |
|
FA-220a |
36.30 |
1.100 |
2.610 |
2.373 |
1,900 |
10,000 |
0.863 |
Notes:
- All Saito engines use " glow fuel" : methanol + 5 to 15 % nitromethane + 16% minimum synthetic castor oil lubricant.
- J/ccfam = energy in Joules per cc of fuel-air mixture
- J/ccfam = ( power_in_watts x 60 x 2 ) / (capacity_in_cc x rpm ) = measure of energy efficiency
|
SAITO single-cylinder, 36 cc, four stroke, petrol (gasoline) engine |
- from http://www.sussex-model-centre.co.uk/shopexd.asp?id=24406
Saito FG-36 with Muffler, Ignition and Motor Mount
The FG-36 is a new departure for Saito - a 36cc petrol engine! The Saito FG-36 is supplied with a CE approved electronic ignition system and a purpose made aluminium engine mount. The carburettor employs a diaphragm pump for reliable fuel feed in any attitude - even the wildest of 3D stunts! This also means that it is not sensitive to the position of the fuel tank, which allows the tank to be positioned to maximise the CG position. You can use forecourt quality petrol mixed in a ratio of 20:1 to 30:1 petrol to oil. The FG-36 is very clean running and is very economical.
Key Features:
- 4-stroke petrol engine from one of RC's top brands
- 36cc displacement rivals similarly sized 2 strokes
- Includes: Ignition, Muffler, Walbro Carburettor and Motor Mount
- Built for the utmost in reliability and performance
- Brings Saito experience to gas enthusiasts
- Comparable in power to Saito FA-220 glow 4-stroke
- Available in traditional silver case
Specification:
- Type: 4 stroke gasoline engine
- Displacement: 36 cc
- Bore: 35 mm
- Stroke: 32 mm
- Cylinders: Single
- Total weight: 1,760 g for Motor + Mount + Muffler + Ignition
- Engine only weight: 1,252 g
- Muffler weight: 86 g
- Crankshaft threads: 8 x 1.25mm (step up is 10mm)
- Benchmark prop: APC 18 x 6W @ 8,300 rpm
- Prop range: 18"-19" x 8"-9”, 20" x 8" (Bolly or Mejzlik)
- RPM range: 1,700 - 9,000 rpm
- Fuel: gas oil mix of 20:1 to 30: 1 (20:1 for break in)
- Mounting dimensions: 124mm x 85mm x 173mm
- Muffler type: Cast
- Power: 2.6 kWatts
- Cylinder type: Ringed
- Starting system: Saito Ignition 4.8v - 6v (capacity more than 1,000mA
- Carburettor type: Walbro/Saito
- Crank type: Ball Bearing
|
SAITO multi-cylinder engines |
The "vibration-free" SAITO FA-182TD
from http://www.horizonhobby.com/Products/Default.aspx?ProdID=SAIE182TD
The Saito FA-300T twin engine
from http://www.horizonhobby.com/Products/Default.aspx?ProdID=SAIE300TTDP
The SAITO FA-170R three cylinder radial engine.
Photograph from http://www.horizonhobby.com/Products/Default.aspx?ProdID=SAIE170R3
|
Saito Engine |
cylinders |
Capacity |
Weight |
Power |
Power / Weight |
rpm range |
fuel efficiency |
|
cc |
kg |
kWatts |
kWatts/kg |
k rpm |
J/ccfam |
||
|
FA-60T |
2 |
10 |
0.75 |
0.671 |
0.894 |
2 - 10 |
0.895 |
|
FA-100T |
2 |
16.4 |
0.82 |
1.044 |
1.273 |
2.5 - 10 |
0.848 |
|
FA-170R |
3 |
27.8 |
1.3 |
1.491 |
1.147 |
2 - 9.5 |
0.753 |
|
FA-182TD |
2 |
30.0 |
1.04 |
1.864 |
1.792 |
2 - 10 |
0.828 |
|
FA-300T |
2 |
50 |
1.75 |
3.504 |
2.002 |
1.8 - 8 |
1.168 |
|
FA-300TD |
2 |
50 |
1.85 |
3.579 |
1.935 |
1.6 - 8.4 |
1.136 |
|
FA-325R5 |
5 |
53 |
2.41 |
2.834 |
0.971 |
1.7 - 7.5 |
0.951 |
|
FA-450R3 |
3 |
75 |
2.9 |
4.101 |
1.414 |
1.2 - 8 |
0.911 |
The Saito FA-325R5 radial engine, from http://www.horizonhobby.com/Products/Default.aspx?ProdID=SAIE325R5D
Pout scales with engine capacity as Pout = 0.073 * x + 0.031 for Pout in kWatts, where x is the engine capacity in cc.
The average power-to-weight ratio for the above engines is 1.727 kWatts / kg. The superiority of the Saito engines in respect of power-to-weight ratios is clear.
The average engine efficiency for the above engines is 0.813 J / ccfam. For the Saito engines, we notice the engine efficiency saturates for engines with a capacity of 17 cc and above.
© Barnard Microsystems Limited 2006 - 2008