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.
Some propeller manufacturers equip the leading edge of their blades with metal reinforcements.
Thanks to innovative and efficient products, E-PROPS has chosen another solution. This solution equips thousands of E-PROPS propellers sold since 2008 all over the world.
E-Props blade with internal leading edge protection
LEADING EDGE PROTECTION : NANOSTRENGTH® ADDITIVE SHOCK
All carbon E-Props propellers have a leading edge 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 a stainless steel 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.
Comparative tests have been made between a Nanostrength® leading edge protection and a stainless steel 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 inox leading edge.
shocks after the tests
stone of the maximum shock (1,12 gr)
speed of the stone at impact : 155 m/sec
Deepth of the maximum impact :
- leading edge inox 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 inox 5/10e.
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.
EXTRA PROTECTION : POLYURETHANE TAPE
In some specific cases, for example :
- very long flights under heavy rains 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.
In those cases, 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.
This tape is claer 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.