E-PROPS : Titanium or Nanostrength Leading Edge Protection
The leading edge of the propellers blades needs a reinforced protection, against stones impact or other projectiles, and sometimes against erosion possibly generated by rain and sand.
E-PROPS proposes two solutions to reinforce its carbon blades : a Titanium leading edge protection and a leading edge protection in Nanostrength shock addtive.
1- TITANIUM LEADING EDGE PROTECTION (V20 RANGE)
2- LEADING EDGE PROTECTION : NANOSTRENGTH® SHOCK ADDITIVE (V12 RANGE) - no longer produced
3- EXTRA PROTECTION : POLYURETHANE TAPE
Since October, 2019, the E-Props propellers V20 range include a Titanium protection on the blade leading edge, 5/10e thick and 40 cm long (on propellers with diameters > 170 cm).
E-Props uses a superplastic forming process of the Titanium, like for the leading edges of the Rafale aircraft.
TITANIUM is the ideal material for blade leading edge protection thanks to its mechanical characteristics :
- specific resistance outpacing Aluminium and Steel
- expansion and elasticity close to carbon – epoxy
- exceptional corrosion resistance (in particular in marine climate)
- Titanium is twice as light as Steel or Inconel
Note:
- if the Titanium leading edge protection is damaged, E-Props can change it, without having to change the whole blade.
- the blades with a Titanium leading edge (V20 range) are specifically manufactured : the mould integrates a place (respecting the blade profiles) where E-Props comes to glue the Titanium leading edge protection. The blades of the V12 range do not have this place and therefore cannot receive Titanium leading edge protection.
The 3-blade Durandal model, full Carbon with Titanium leading edge protection, diameter 175 cm, weights 2 kg only (hub + blades + screws).
E-Props blade with Titanium leading edge protection
Each E-Props carbon propeller which has no Titaniumm leading edge protection has a protection with Nanostrength® additive shock in the epoxy resin.
Made by ARKEMA, Nanostrength® are new innovative additive to reinforce epoxy resin, with high energy absorbing capability.
The resin with Nanostrength® is injected in the leading edge during the manufacturing of blade in RTM (Resin Transfer Molding). It is completely integrated in the blade, without unsticking risks or materials incompatibility, and with a perfect respect for profiles.
This additive has been selected because the leading edge protection of the E-Props propellers range is more resistant as Steel or Inconel 5/10e (see COMPARATIVE TESTS below), and far more easier to repair in case of shocks.
It has been developped for the UAV with Rotax 914 that E-PROPS equips since 2008, and for ultralights and aircraft which are flying in Africa, on non-prepared airfields in laterite.
E-PROPS customers prefer this type of leading edge reinforcement to Steel or Inconel one (we are not talking here about Titanium), because :
- integrated in the blade : no risk of detachment
- no part in Steel or Inconel = no risk of galvanic corrosion
- reinforcement all along the leading edge
- no extra weight on the tips : smaller Moment of Inertia
- possibility to easily repair the leading edge protection, even on a big impact (when a metallic leading edge must be changed - or the whole blade) : every pilot can make this repair himself, with the E-PROPS repair kit (available in this e-shop)
Please note : the V12 range blades have a Nanostrength resin leading edge. They do not have a reserved place to put a Titanium leading edge.
-
In 1901, the French engineer Georges Charpy proposed the "pendulum sheep" still used today.
The purpose of the Charpy test is to determine the impact resistance of materials. It allows to measure their resilience, that is to say the resistance of a material to shocks.
The E-PROPS team has made its own Charpy pendulum :
Some series of tests have been made to compare a Nanostrength® resin leading edge and a 5/10e Inconel leading edge.
Deepth of the maximum impact :
- leading edge Inconel 5/10e = 2,1 mm
- leading edge resin Nanostrength® = 0,9 mm
The tests results show that :
1/ The leading edge resin Nanostrength® present much less important damages than leading edge 5/10e Inconel.
2/ The protection with shock additive is integrated all along the leading edge, because the shocks do not happen only at tips.
3/ The leading edge with Nanostrength® shock additive does not lead either unsticking or electrolytic couple.
4/ The possible impacts are very easy to repair. A repair kit is available on this e-shop.
In some specific cases, for example :
- seaplanes
- very long flights under very heavy rains (like monsoon) at high engine RPM - paramotors : barefoot flights (just above the water surface or the beach) (please note that E-PROPS does not recommend those types of extreme flights) it could be interesting to put an extra protection on the blades leading edge, when they have no Titanium leading edge protection.
in those case, protect the blades leading edge is interesting !
For those types of flights, E-PROPS recommands to add a polyurethane protection tape.
This polyurethane protection tape is made from very high performance elastomer, resistant to erosion, abrasion, punctures, minor impact damage and tears. Its formula is also resistant to ultraviolet light. Its thickness is 0,36 mm.
This specific polyurethane protection tape is used on certified helicopter rotor blades. This protection tape does not impact the aerodynamic performances of the blades. The E-PROPS team has made many tests which all show that the performance gap between a blade with a polyurethane protection tape and a blade without this tape is not measurable.
Since 1rst of January, 2019, E-PROPS equips all propellers blades for Ultralights / Aircraft (when they have no Titanium leading edge protection) with this polyurethane tape (as standard). This option is free.
This tape is clear and adhesive on one side. It can be painted or applied on painted surfaces.
The relative rigidity of this material makes it very easy to install and change.
It is available on this e-shop, in kits of different lengths.
E-PROPS proposes two solutions to reinforce its carbon blades : a Titanium leading edge protection and a leading edge protection in Nanostrength shock addtive.
E-Props blade with Titanium leading edge protection
1- TITANIUM LEADING EDGE PROTECTION (V20 RANGE)
2- LEADING EDGE PROTECTION : NANOSTRENGTH® SHOCK ADDITIVE (V12 RANGE) - no longer produced
3- EXTRA PROTECTION : POLYURETHANE TAPE
1- TITANIUM LEADING EDGE PROTECTION (V20 RANGE)
Since October, 2019, the E-Props propellers V20 range include a Titanium protection on the blade leading edge, 5/10e thick and 40 cm long (on propellers with diameters > 170 cm).
E-Props uses a superplastic forming process of the Titanium, like for the leading edges of the Rafale aircraft.
TITANIUM is the ideal material for blade leading edge protection thanks to its mechanical characteristics :
- specific resistance outpacing Aluminium and Steel
- expansion and elasticity close to carbon – epoxy
- exceptional corrosion resistance (in particular in marine climate)
- Titanium is twice as light as Steel or Inconel
Note:
- if the Titanium leading edge protection is damaged, E-Props can change it, without having to change the whole blade.
- the blades with a Titanium leading edge (V20 range) are specifically manufactured : the mould integrates a place (respecting the blade profiles) where E-Props comes to glue the Titanium leading edge protection. The blades of the V12 range do not have this place and therefore cannot receive Titanium leading edge protection.
The 3-blade Durandal model, full Carbon with Titanium leading edge protection, diameter 175 cm, weights 2 kg only (hub + blades + screws).
E-Props blade with Titanium leading edge protection
2- LEADING EDGE PROTECTION : NANOSTRENGTH® SHOCK ADDITIVE (V12 RANGE) - no longer produced
Each E-Props carbon propeller which has no Titaniumm leading edge protection has a protection with Nanostrength® additive shock in the epoxy resin.
Made by ARKEMA, Nanostrength® are new innovative additive to reinforce epoxy resin, with high energy absorbing capability.
The resin with Nanostrength® is injected in the leading edge during the manufacturing of blade in RTM (Resin Transfer Molding). It is completely integrated in the blade, without unsticking risks or materials incompatibility, and with a perfect respect for profiles.
This additive has been selected because the leading edge protection of the E-Props propellers range is more resistant as Steel or Inconel 5/10e (see COMPARATIVE TESTS below), and far more easier to repair in case of shocks.
It has been developped for the UAV with Rotax 914 that E-PROPS equips since 2008, and for ultralights and aircraft which are flying in Africa, on non-prepared airfields in laterite.
E-PROPS customers prefer this type of leading edge reinforcement to Steel or Inconel one (we are not talking here about Titanium), because :
- integrated in the blade : no risk of detachment
- no part in Steel or Inconel = no risk of galvanic corrosion
- reinforcement all along the leading edge
- no extra weight on the tips : smaller Moment of Inertia
- possibility to easily repair the leading edge protection, even on a big impact (when a metallic leading edge must be changed - or the whole blade) : every pilot can make this repair himself, with the E-PROPS repair kit (available in this e-shop)
Please note : the V12 range blades have a Nanostrength resin leading edge. They do not have a reserved place to put a Titanium leading edge.
-
COMPARATIVE TESTS
Comparative tests have been made between a Nanostrength® leading edge protection and a Inconel 5/10e with a system called "Charpy pendulum" :In 1901, the French engineer Georges Charpy proposed the "pendulum sheep" still used today.
The purpose of the Charpy test is to determine the impact resistance of materials. It allows to measure their resilience, that is to say the resistance of a material to shocks.
The E-PROPS team has made its own Charpy pendulum :
Some series of tests have been made to compare a Nanostrength® resin leading edge and a 5/10e Inconel leading edge.
shocks after the tests
tests results
stone of the maximum shock (1,12 gr)
speed of the stone at impact : 155 m/sec
speed of the stone at impact : 155 m/sec
Deepth of the maximum impact :
- leading edge Inconel 5/10e = 2,1 mm
- leading edge resin Nanostrength® = 0,9 mm
The tests results show that :
1/ The leading edge resin Nanostrength® present much less important damages than leading edge 5/10e Inconel.
2/ The protection with shock additive is integrated all along the leading edge, because the shocks do not happen only at tips.
3/ The leading edge with Nanostrength® shock additive does not lead either unsticking or electrolytic couple.
4/ The possible impacts are very easy to repair. A repair kit is available on this e-shop.
3- EXTRA PROTECTION : POLYURETHANE TAPE
In some specific cases, for example :
- seaplanes
- very long flights under very heavy rains (like monsoon) at high engine RPM - paramotors : barefoot flights (just above the water surface or the beach) (please note that E-PROPS does not recommend those types of extreme flights) it could be interesting to put an extra protection on the blades leading edge, when they have no Titanium leading edge protection.
in those case, protect the blades leading edge is interesting !
For those types of flights, E-PROPS recommands to add a polyurethane protection tape.
This polyurethane protection tape is made from very high performance elastomer, resistant to erosion, abrasion, punctures, minor impact damage and tears. Its formula is also resistant to ultraviolet light. Its thickness is 0,36 mm.
This specific polyurethane protection tape is used on certified helicopter rotor blades. This protection tape does not impact the aerodynamic performances of the blades. The E-PROPS team has made many tests which all show that the performance gap between a blade with a polyurethane protection tape and a blade without this tape is not measurable.
Since 1rst of January, 2019, E-PROPS equips all propellers blades for Ultralights / Aircraft (when they have no Titanium leading edge protection) with this polyurethane tape (as standard). This option is free.
This tape is clear and adhesive on one side. It can be painted or applied on painted surfaces.
The relative rigidity of this material makes it very easy to install and change.
It is available on this e-shop, in kits of different lengths.
