Bell and Lockheed Martin are teaming up on the V-280 Valor tiltrotor aircraft which the helicopter manufacturer is pitching for the US Army's Future Vertical Lift (FVL) programme.
Bell says additional partners will be announced in the coming months.
"We are very excited about teaming with Lockheed Martin on the V-280," says John Garrison, president and chief executive officer of Bell Helicopter.
Dale Bennett, Lockheed Martin executive vice-president for mission systems and training, says: "Our efforts will allow the US Army to take advantage of the advanced technology and maturity we've achieved in integrated avionics, sensors, and weapons."
The army recently selected the Bell V-280 Valor along with designs from a Boeing-Sikorsky team and AVX Aircraft to enter negotiations for its Joint Multi-Role (JMR) Technology Demonstrator (TD) programme. JMR TD is a precursor to the FVL effort.
Contracts are expected to be awarded this month.