E-PROPS: DURANDAL & EXCALIBUR Propellers Data Sheet

At E-Props, our team does not offer a "universal blade" that fits everything, that can be cut to size at will, and that is therefore never ideally suited to the aircraft's mission. Every E-Props propeller is designed and developed for the characteristics of the engine and its gearbox, engine cooling airflow, a defined aircraft speed range, the aircraft configuration (tractor, pusher, high/low wing) and its use (cruise, towing, STOL...). E-Props has developed numerous blade models, with several chord widths and airfoils, in tractor and pusher configurations — each model available in 2, 3, 4 or 5 blades. DURANDAL is available in 18 diameters, from 120 to 209 cm; EXCALIBUR from 120 to 194 cm.

Maximum power and rotation speed

Power (Watt) = torque (N.m) × rotation speed (rad/s). The rotation speed of each propeller is indicated on the Identification Sheet supplied with it — example, for E-Props models on Rotax 9-series engines: maximum speed of 2,600 RPM at the propeller (272.3 rad/s), speed at the propeller = max engine speed / reduction ratio.

E-Props has developed an exclusive carbon spacer system, replacing the usual aluminium spacers: 13 times lighter, free of charge regardless of the chosen length, extremely easy to fit (no unnecessary hardware), orders made easy with interactive drawings. See details: carbon spacers.

E-Props spinners are 100% carbon, very strong and ultra-light, available in 15 diameters for the V20 range (from 210 to 380 mm). See details: E-Props spinners.

DURANDAL & EXCALIBUR propellers have a strong ESR effect: their behavior is close to that of an in-flight variable-pitch propeller, with high efficiency across the aircraft's whole speed range. This is why the blade pitch adjustment must be subtle and precise. The ideal engine RPM is measured in flight, not on the ground: because of this ESR effect, static RPM is not a meaningful figure, as these propellers are designed to reach full thrust just after the start of the take-off roll (in static, the blades are slightly stalled). The adjustment depends on the engine type.

How to adjust the blade pitch

The best solution to adjust the blade pitch is to watch the video below. See also the manuals.

E-Props pitch adjustment

Below, how to position the E-Props digital protractor, strongly recommended to adjust the blade pitch:

→ Order the E-Props digital protractor.

Max. pitch tolerance between blades: 0.3° (beyond that, risk of vibration). The protractor must stay switched on throughout the measurement of all blades — if it switches off, the measurement must be repeated for every blade. Trick to keep it on: put it in your pocket between measurements, its movement keeps it from switching off.

Adjustment on Rotax 4-stroke 9-series engines

On Rotax 4-stroke 9-series engines (912, 912S, 912iS, 914, 915iS), the pitch giving the best performance across the aircraft's whole speed range is obtained at 5,500 RPM full throttle, level flight.

Procedure: (1) adjust the pitch to the value recommended on the Identification Sheet or in the propeller's catalog description (a simple indication, not an obligation); (2) on the ground, full power on brakes or chocks — aim for 5,000 to 5,800 RPM (increasing the pitch by 0.6° reduces speed by 100 RPM, and vice versa); (3) in flight, level off at cruise altitude (below 10,000 ft), full throttle: 5,500 RPM (± 50 RPM) means a perfect setting, otherwise land and redo the ground setting.

Example: at full throttle the engine runs at 5,700 RPM against a 5,500 RPM target — a 2×100 RPM gap, so increase the pitch by 2×0.6° = 1.2°. Reaching 5,500 RPM at full-throttle level flight does not mean cruising at that speed: it is only the reference value for the setting.

Adjustment on Rotax 2-stroke 582 engines

On Rotax 2-stroke engines (532, 582), the pitch giving the best performance across the aircraft's whole speed range is obtained at 6,800 RPM full throttle, level flight.

Procedure: identical to the 4-stroke procedure above, targeting 6,000 to 6,800 RPM on the ground (increasing the pitch by 0.5° to 0.9° — depending on the gearbox — reduces speed by 100 RPM, and vice versa), then checking full throttle level flight: 6,800 RPM (± 50 RPM) means a perfect setting.

Example: at full throttle the engine runs at 6,600 RPM against a 6,800 RPM target — a 2×100 RPM gap, so decrease the pitch by 2×0.7° = 1.4°. If values are inconsistent, check that the correct gearbox is fitted (the casing can show a ratio that does not match its internal gears) and that the tachometer (especially a needle type) is properly calibrated.

What makes the plane take off is not engine RPM, but the propeller's thrust.

E-Props propellers, being ultra-light, respect with margin the moment-of-inertia limits set by engine manufacturers; each model's value is calculated then verified by measurement on a test bench (see moment of inertia). Every propeller leaves the workshop perfectly balanced, on a digital frequency test bench (see balancing).

E-Props propellers are certified ASTM F2506-26 (LSA standard), and some are EASA certified — see all TBO durations. In France, if your E-Props propeller is not listed on your ultralight's Identification Sheet, the DGAC requires a major modification: a quick declarative procedure (an exchange of 2 letters with your district) — see details: major modification.

Small leading-edge impacts are easily repaired (epoxy resin, no paint or varnish) — a repair kit is available in this shop, and on the V20 range the Titanium leading edge can be replaced without changing the whole blade. It is also possible to change a single blade. See details: repairs and spare blades.

E-Props runs extensive tests on all its models (see ground tests — example: video of the V20 range test campaign, April 2020, tensile, bending and torsion tests: carbon parts as strong as the Rotax gearbox shaft).

Fixing screws must be tightened with a torque wrench, following exactly the values given in the Manual supplied with each propeller. Maintenance: visual inspection before every flight; screw tightening checked every 100 h and/or 6 months (V20 range), or every 200 h and/or 12 months (Titanium screws); cleaning with soapy water or a multi-surface cleaner.

Installation and maintenance manuals, as well as CAD (stp) files for the blades, hubs, spinners and spacers of this range, are all gathered on the Manuals and Documentation page.