E-PROPS carbon spacers : the best solution

When the engine is inside the engine fairings, usually propellers manufacturers propose aluminium spacers, in order to space the propellers from the fairings.
But aluminium spacers are very heavy (20 g/mm – for example a spacer length 120 mm weights 2,4 kg), difficult to assemble (with many screws and bolts), and expensive.

E-PROPS has developed an exclusive system to replace the usual aluminium spacers : CARBON ESU SPACERS :
✗  The E-PROPS ESU spacers are ultra-light (13 times lighter : 1,5 g/mm instead of 20 g/mm for an aluminum spacer).
✗  The “E-PROPS ESU spacer” option is free of charge, regardless of the chosen length.
✗  E-PROPS ESU spacers are a part of the hub, easy to install (no unnecessary screws and bolts, thus avoiding vibrations).
✗  Orders are facilitated by the interactive drawings published by E-PROPS.

E-PROPS Carbon Spacers (1,5 g/mm)   /   Standard Aluminium Spacers (20 g /mm)
E-PROPS spacer : 13 times lighter !

The hubs of the E-PROPS ground adjustable pitch propellers are simple and light.
They are in 3 parts:
✗  Two flat carbon parts in which the blade feet are positioned, called HHU1 and HHU2.
✗  A carbon spacer that allows the propeller to be fixed to the engine, called ESU, which has a variable length according to the customer’s wishes.

the E-PROPS hub + spacer, an exclusive ultra-light system

The length of the E-PROPS spacer depends on the position of the engine cover and spinner.
The measurement of the E-Props spacers are not the same as the aluminum spacers on other brands of propellers. The position of the spinner is also different. Therefore it is necessary to take the measurements as indicated by E-PROPS.

In leisure aviation, there are not large series as in the automotive industry.
Aircraft manufacturers are used to change somes details on their aircraft, and particularly engines covers. Sometimes the engines come outside the covers, and sometimes are inside. It depends on the versions, and it is difficult for propellers manufacturers to know all versions of all aircraft.

Depending on the aircraft, there are 3 configurations:

A) The gearbox flange reaches the edge of the engine cover
=> you don’t need a spacer. To facilitate the assembly and disassembly of the covers, 5 mm can be added to the spacer. See the interactive diagram in the following paragraph.

the flange of the gearbox is at the edge of the engine cover

B) The gearbox flange is inside the engine cover
=> a spacer is essential. An extended hub or E-PROPS spacer is an excellent solution: lightweight, very strong and economical.
To know which length to choose, see the interactive diagram in the following paragraph

the gearbox flange is inside the engine cover

C) The gearbox flange comes out of the engine cover
=> you don’t need any spacer
If your gearbox flange comes out from the engine cover a lot, the E-Props system allows you to shift the spinner backwards, up tto 20 mm. See the interactive diagram in the next paragraph.

the flange of the gearbox comes out of the engine cover by 20 mm – the cover can go back

Click here => Spacer Length : measure to take


✗  Mass gain
Mass in grams of the E-PROPS carbon spacer V20 range = only 1.5 g/mm, including screws and bolts
. This is to be compared to the 20 g/mm of an aluminium spacer with screws and bolts.
Example for the extension of a 120 mm on the Savannah ultralight :
– mass of the carbon spacer = 120 mm x 1.5 g/mm = 0.180 kg
– mass of an aluminium spacer = 120 mm x 20 g/mm = 2.4 kg
=> a gain of 2.2 kg only on the Savannah’s extension function!

✗  Money saving
E-Props extended hubs are at the same price as standard hubs. So there is no need to buy an extra spacer.
For example, an aluminium spacer for Savannah (120 mm) can cost up to 300 EUR…
=> a nice money-saving for E-PROPS customers.

✗  Exist in 38 lengths
E-PROPS has developed an automatic machine that takes out the spacers at the desired length.
The E-PROPS V20 carbon spacer system is available in 38 lengths, from -20 to +170 mm, in 5 mm steps. This ensures that you will find exactly the right length for your assembly.

✗  Gearbox protection
If too much mass is attached to the gearbox unit, its service life is significantly reduced. Heavy propellers create a high risk of breakage of the gearbox unit.
Reducing the mass of the spacer limits this risk.
ROTAX does not recommend the use of propeller extensions longer than 120 mm.
This of course applies to aluminium spacers, as the weight of the spacer (more than 2 kg) would then be too high for the gearbox.
E-PROPS, with its ultra-light carbon spacers (example: the 170 mm spacer weighs only 255 g), allows solutions to keep the propeller away from the engine fairings up to 170 mm, without risk to the gearbox.

✗  Reduction of vibrations
The propeller is directly centred by the hub. This avoids spacer stacks and the various screws and pins, which often generate vibrations.
A simple and straightforward system like E-PROPS greatly reduces the risk of vibration.

✗  A reliable and durable system
E-PROPS hubs, whether standard or with spacer, are extremely strong.
Material: 100% carbon + high temperature epoxy resin
Injection according to the RTM (Resin Transfer Molding) process
Compact volume hub: for minimum drag and optimised engine cooling
Max TBO : 4,000 hours

✗  Simple assembly
The E-PROPS spacer allows quick and easy assembly, with the minimum number of parts. The centering pins, mandatory on ROTAX 9 series engines, are integrated in the carbon part, whereas they have to be added on the aluminum spacers (weight of the 6 Rotax pins = 125 g).

comparative : carbon spacer / aluminium spacer
E-Props integrated drive lugs

E-PROPS : Light is Right !

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