NTPT's sales & marketing director Joe Summers discusses the application of thin ply prepregs in the Solar Impulse 2 zero-fuel plane in the May 2016 issue of CompositesWorld magazine.
For this solar-powered aircraft, the essential prerequisite was an extremely light aerostructure, explains CompositesWorld. The raw material that ultimately satisfied this need proved to be very thin composite tapes. The airframe’s main and rear wing spars, fuselage and empennage were constructed from NTPT's thin ply epoxy prepregs. For this project, NTPT™ spread M46J 12K ultra high-modulus PAN carbon tow from Toray to yield very thin 25 g/m2 and 100 g/m2 unidirectional (UD) tape. The UD tapes were resin-impregnated during the process and then converted into ±45° preforms up to 27 m long by 1.2 m wide using NTPT’s automated tape laying (ATL) machine. The preforms for Solar Impulse 2 (Si2) were then shipped to composites manufacturing specialist Decision SA in Switzerland.
As Joe Summers tells CompositesWorld, this project is a big success for all parties involved: “The successful flight of Si2validates the choice of products. Thin ply materials have created a strong, lightweight structure capable of circumnavigating the globe with only solar power."
He adds that the project further refined NTPT’s capability to manufacture, handle and transport large preforms.
Summers also points out that low-power, long-duration flight is opening possibilities in such diverse applications as commercial travel, pseudo-satellites, weather prediction and military purposes. A promising high-performance market for the technology used for Si2 is, in fact, the so-called High Altitude Pseudo-Satellite (HAPS), or solar-powered drones, which need no launch vehicles and are sustainable and, therefore, less costly alternatives to rocket-launched satellites.
NTPT™ is pushing its thin ply technology even further, targeting UD tapes as thin as 15 g/m2, to satisfy these and other high-performance markets.
Additionally, Summers says NTPT™ is constantly expanding the range of high-modulus and ultra high-modulus fibres that can be made into thin ply prepregs: “Higher modulus thin materials are vital for very lightweight and stiffness-critical components for these types of craft.”
For example, NTPT™ can already manufacture thin ply prepregs from Toray’s M55J (540 GPa) and GRANOC YSH70 (720 GPa) from Nippon Graphite Fiber Corp to weights as low as 50 g/m2.
The complete article, Solar Impulse 2: Pulse on the Future, is available on the CompositesWorld website.