Light Innovative Flying Tiltrotor Tail (LIFTT) will develop and manufacture the tail section of the Next Generation Civil Tiltrotor (NGCTR). Advanced thermoplastic material will be used for the primary structure for which innovative induction welding techniques will be further developed. The NGCTR will become the first flying platform worldwide to demonstrate the benefits of thermoplastics in primary structures.
A clear step beyond state of the art
Through this program first-hand experience on a flying demonstrator can be obtained in near operational conditions. A successful flying demonstrator will open the door for wider application of this technology in commercially operated vehicles of all sorts. This will enable aircraft OEMs to design aircraft with ever lower structural weight and consequently equivalent lower energy consumption and lower CO2 and NOx emissions.
Thermoplastics materials are more ductile than thermosets and are therefore more robust with respect to impact damage. Advanced welding techniques allow a high level of parts integration, eliminating to a large extent the application of costly fasteners, commonly used in traditional thermoset composite parts. Also hot forming processes allow more out of autoclave operations, which results in dramatically more energy-efficient production when with thermoset materials. In economic terms, these technical advantages enable an approximately 10% lower production cost level and 5-10% reduction in maintenance cost.
To develop and manufacture the tail section for the NGCTR, achieving the maximum weight benefits possible for the current state of the art through the application of new thermoplastic materials. LIFTT is aiming for 20% weight benefit for a series production design when compared to aluminium and 5-10% when compared to thermoset composites.
To develop a new design and industrialization methodology, reducing lead time (T), cost (C) and risk (R) in the design phase by at least 50%. In the design steps, changes can be more easily included and reviewed on cost, weight and associated risk before adopted in final design, where KBE tools support the design- and analysis processes.
Activities, induction welding of:
UD CF PEKK laminates, standard lap joints with constant thickness for which several parameter settings are researched and coupons are tested afterwards.
UD CF PEKK laminates, standard lap joints with variable depth/variable thickness for which combinations of a variable welding speed and a variable welding current are researched and coupons are tested afterwards.
UD CF PEKK laminates, without external pressure and heatsink material on top of the laminates.
A vacuum bag and air cooling is used instead.
Demonstrator Development: Preliminary Design Phase
The LIFTT project started officially in March 2018, with a Kick-Off meeting with the project partners in Cascina Costa at the facilities of Leonardo Helicopters. During the Kick-Off meeting we discussed the objectives, scope and time schedule of the project. A few weeks later, the LIFTT team received a requirements list, which was used as basis for the discussions during the requirements review, held in August 2018. In between, the LIFTT team and Leonardo Helicopters organized several technical workshops to work together on the initial concept of the V-Tail, required to enter the PDR phase.
After the requirements review, the LIFTT team entered the PDR entry phase. Leonardo Helicopters supplied the entry and exit requirements of the PDR phase and the LIFTT team matured the concept accordingly. This resulted in the successful closure of the PDR phase in February 2019.
Technology Development: Thermoplastic composites
Within LIFTT, several thermoplastic composites technologies are considered. Some of them will be implemented into the flying tail demonstrator and a few will be developed for implementation beyond this project.
Recycled carbon fiber reinforced thermoplastic hinge covers (flying)
The recycling process consists of several steps. Carbon fibre reinforced polyphenylene sulfide waste material is collected and shredded to flakes with a long fibre length.
The material is heated and mixed in a low-shear mixer and compression moulded to a part. This solution offers the possibility to process long fibre lengths, known to exhibit high modulus, strength and impact properties.
Out-Of-Autoclave press consolidated thermoplastic front spar (flying)
The Hot Forming & Press Consolidation development of AS4D/PEKK supports the production of complex and integrated small to mid-size carbon fibre parts for aerospace applications.
Its intention is to enclose the gap between the benefits of stamp forming (low curing time, high rate, low labour) combined with the larger scale and complex parts which are currently manufactured with an autoclave cycle.
Additive manufactured hinge (not flying)
Currently AM technology has found its first applications in aircraft at non-flight critical parts, mostly applying
well known machining constraints to the shape of the component. In this case, standard calculation methods can be used for substantiation. Next step is to develop a design process supporting the application of flight
critical parts with optimized shapes. By investigating the outer boundaries of the AM technology including
topology optimization and testing (with emphasis on fatigue life) the results, the intention is to derive design principles and calculation methods for robust lightweight design solutions.
Automated fibre placed thermoplastic skin (flying)
The main advantages of Automated Fibre Placement (AFP) of thermoplastic materials are material and
labour savings, quality improvement, and accurate fibre placement at any angle.
AFP technology has been
researched at FAE for many years. The latest status of AFP is the implementation of continuous ultrasonic
tacking of AS4D/PEKK.
GKN Fokker Aerostructures
3351 LB Papendrecht,
NLR – Royal Netherlands Aerospace Centre
P.O. Box 90502
1006 BM Amsterdam
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