Details of the Cyclon .40 PR Pylon Racing Engine
Performance Data
Propeller Dia Thrust Coeff. Power Coeff. RPM Density Power Thrust
Ct 0
Cp 0
P 0
T 0
R1 Rüdiger Keck 0.185 0.1249 0.0697 25050 1.195 1295 30.1
0.185 0.1249 0.0697 25600 1.205 1394 31.8
0.185 0.1249 0.0697 26000 1.208 1464 32.8
F1 Olivier Allais 0.182 0.1298 0.0899 17000 1.205 492 13.8
F1 (Nelson engine) 0.182 0.1298 0.0899 25900 1.208 1744 32.1
S1 Sasha Smoletsev 0.178 0.1353 0.0946 25200 1.208 1512 28.9
A1 Ranjit Phelan 0.187 0.1249 0.0923 24000 1.208 1610 29.2
V1 Verano Copy 0.188 0.0999 0.0820 26000 1.205 1887 28.2
0.188 0.0999 0.0820 25600 1.208 1806 27.4
0.188 0.0999 0.0820 25800 1.208 1849 27.9
0.188 0.0999 0.0820 25890 1.195 1848 27.8
0.188 0.0999 0.0820 26000 1.208 1892 28.3
- The trailing "0" means "static condition" i.e. v = 0.
- The engine was running on 80/20 FAI fuel during all my tests.
- Weather conditions were close to standard conditions, corrections were below measurement accuracy.
- the propeller coefficients were determined by wind tunnel tests.


Performance Chart
My test results and another performance curve, taken from a japanese web site (forgot to bookmark that page, though).

The test data matches the performance curve found on the japanese web page quite well. The data was taken using propellers, which were calibrated in a wind tunnel. It is possible, that the calibration data of the R1 prop are a bit on the low side concerning power input, due to Reynolds number differences.

Some Technical Data
Engine 375 g
Tuned Pipe 70 g
Exhaust 172°...180° (non-horizontal edge shape, raised center)
Transfer, center 128°  
Transfer, side 128°...132° (non-horizontal edge shape)
Rotary Valve 232° 200° ATDC ... 432°ATDC


Mounting Dimensions

Dimensions of a plate to mount the Cyclon 40 on my test bench.

Photo Gallery (click on the photos to enlarge)

The cyclon after an explosion...

Note the asymmetrical oil channel to the lower lug and the shape of the transfer ports.

The piston has been machined from solid material. Barely visible: the shape of the exhaust port.

The heart of the engine: sleeve, piston and crankshaft. The fit between crankshaft and rear bearing seems to be a bit too loose. The counterweight of the crankshaft is open towards the rear and closed by a disk on its front side.

The engine comes with spinner assembly and two precision wrenches (the lower one is needed to remove the screw-on head.

On top of the crankcase you can see the thread for the head.

The disk rotor comes well balanced (drill marks on bottom and milled area on top) and the crankcase cover has small recesses to reduce friction between rotor and casing.

The rear bearing.
The cylinder head, a screw-on cap design, fits Nelson style glow plugs.
The engine with its nice pipe, as manufactured by Kalmykov (in very good quality, maybe a bit expensive).

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Last modification of this page: 21.05.18

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