The use of external human resources is well known as outsourcing (outside resource using) and is practiced since many years e.g. in book-keeping, accounting, legal systems, patent business etc. Why not to use outsourcing for R&D and applications engineering tasks?
I'm offering my freelance work in cases of project management. There's no reason for fear concerning loss of internal knowledge because of my objective, serious and independent work.
There are many possibilities for working on projects; the following list gives a short overview:
Road-mapping (examination of influences and key factors, scenario techniques for the design of future products and technologies)
Ecological examination of building materials and constructions, studies on the ecological aspects to develop "eco-intelligent" products
Product development and technical marketing support
New measuring methods development
Information supply (patents, materials, literature etc.)