E-PROPS HI-TECH CARBON PROPELLERS



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E-PROPS : the most efficient propellers

 

 

 

The E-PROPS are the WORLD's LIGHTEST, STRONGEST and QUIETEST propellers, and they give the best EFFICIENCY.

 

special design eprops

special design = the best efficiency

 

 

For a paramotor use, the propeller must :

- be exactly adapted to the engine and the RPM

- be ultra-light to guarantee a long life to the engine

- give the best thrust

 

The E-PROPS propellers are very different from the other propellers. They have special profiles, patented designs (for example SCIMITAR), and special position of the blades to reduce the blades drag, so to obtain the best thrust.

More data here : PROPELLERS DESIGN

 

 

 

PROPELLERS EFFICIENCY

 

Propulsion efficiency factor is calculated from propeller diameter and engine power. This efficiency factor is the max achievable propeller efficiency. Then, it is up to the propeller designer to come closer to this limit.

 

The E-PROPS design department consists of 5 technicians and engineers. The head of this department is Jérémie Buiatti, who designs propellers since 2006 and has implemented the internal software LmPTR©. This complex software performs a detailed aerodynamic flows analysis and a mechanical behavior analysis of the propeller. It is implemented from an advanced language and contains more than 62000 code lines.


This software allows the team to imagine new propellers concepts, by using particular geometries and profiles developed inhouse. That is why E-PROPS propellers are very different from other propellers proposed at present on the market.

 

E-PROPS has developed an efficiency software => MODELIZATION PROGRAM

This simplified modelization allows a first approach for information purposes. It does not take into account the mechanical aspects imposing on blades a certain geometry. It calculates the propeller's efficiency at a specified point of functioning.

 

When we speak of efficiency, we obviously speak of thrust and also of fuel consumption. A propeller which has a better efficiency allows to reduce the fuel consumption of the engine. The E-PROPS propellers have all a thin chord (the width of the blade). A thin chord generates less drag than a wide chord and leads to a better efficiency of the propeller, so reduces fuel consumption. On average, the use of a E-PROPS propeller allows to save between 6 and 9% of fuel at the same engine RPM (it depends on the blades geometries).

 

 

 

NUMBER of BLADES

 

For a paramotor use (it means low speed), for the same diameter, more blades = more efficiency.

 

It is possible to see this by using our MODELIZATION PROGRAM. A 3-blades has a best efficiency (= a best thrust) than a 2-blades.

Example :

Thrust measured with propellers

for Vittorazi Moster 185 engine red 2,68

all in diameter 130 cm =>

- 2-blades : 82 kg

- 3-blades : 86 kg

- 4-blades : 90 kg

- 6-blades : 92 kg

 

 

 

6-blades eprops

Please note :

This is true if the blade form is exactly adapted to the configuration : a blade of a 2-blades propeller mounted on a 3-blades or 4-blades hub would not give the best performances.

The "universal" blade for any configuration does not exist. Every propeller has a dedicated blade geometry, or the efficiency would not be the best.

At this date (2018-04-18), by E-PROPS, it exists 185 different blades geometries and more than 12 different diameters.

 

 

 

DIAMETERS

 

The increase of the diameter is better for the efficiency, because of the improvement of the pusher efficiency. More thrust is obtained with a propeller with a diameter of 150 cm than with a propeller with a diameter of 125 cm. With the same number of blades, the thrust gap depends on the diameters and on the engine + reducer.

For more information, see here : GENERAL INFORMATION

Examples :

Thrust measured with propellers

for Vittorazi Moster 185 engine red 2,68

all 2-blades =>

 

- diameter 115 cm : 74 kg

- diameter 125 cm : 80 kg

- diameter 130 cm : 82 kg

- diameter 140 cm : 87 kg

- diameter 160 cm : 95 kg


diamètre 150 e-props

E-Props dia 150 cm Nitro 200

Please note :

All sets of engines - reducers can not be equiped with big diameters propellers. One data has to be verified : the peripherical speed (on tips) must not exceed Mach 0,65, or the noise would be very important.

 

 

 

DIVERS

translation in progress

 

1 - Comparatif bipale / tripale : certains disent que le sillage de la 3ème pale d'une hélice tripale croise le sillage des deux autres pales et que cela diminue le rendement.

C'est faux. Les pales ne passent jamais dans le sillage les unes des autres. C'est physiquement impossible, car le sillage des pales est emmené par le souffle de l'hélice.

Démonstration en image :

sillage pales hélice corsair

Les trainées de condensation générées par l'hélice de ce Corsair matérialisent les sillages

On voit bien que les sillages sont poussés à l'arrière par le souffle de l'hélice

 

Il existe un seul cas où le sillage des pales se croise : c'est lorsque l'on inverse le pas des pales sur les hélices à pas variable. On appelle cela "reverse" ou "inversion de poussée". C'est un dispositif permettant d'orienter vers l'avant la poussée exercée par un moteur dans le but de ralentir l'avion et de réduire les distances de freinage lors de l'atterrissage. Pendant la reverse, le bruit des pales passant dans leur propre sillage est très caractéristique.

 

 

2 - Cavitation des hélices d'avions

La cavitation est un phénomène hydrodynamique découvert en 1917, qui peut apparaitre dès qu’un objet solide se déplace à plus de 15 noeuds dans l’eau. Il s'agit de la formation de bulles de gaz et de vapeur dans un liquide soumis à une dépression. La cavitation peut provoquer une perte de rendement, voire même la destruction des hélices marines. Ce phénomène ne peut en aucun cas concerner les hélices qui fonctionnent dans l'air, comme les hélices d'avions. C'est donc à tort que ce terme est utilisé en aéronautique.

En fait, il faut parler de "flutter" (ou couplage aéroélastique), qui est un effet dû à la sur-vitesse d'une pale, et qui entraîne un bruit de ronflement très caractéristique. Sur une hélice, ce n'est pas forcément dangereux, s'il ne dure pas trop longtemps.

 

 

 

 

E-PROPS HI-TECH CARBON PROPELLERS