As industry readies its experimental vertical-lift aircraft for Army evaluation, aviation officials have made clear they do not consider the two Joint Multi-Role Technology Demonstrators (JMR-TD) to be prototypes of future helicopters.

Maj. Gen. William Gayler, chief of the Army Aviation Center of Excellence (AACE) said Bell Helicopter’s V-280 Valor next-generation tiltrotor and the SB-1 Defiant built by Boeing [BA] and Sikorsky will simply demonstrate current vertical lift technology and inform requirements for the follow-on Future Vertical Lift (FVL) family of aircraft that eventually could replace the Army’s legacy rotorcraft.

The Army could choose one or both designs for various mission sets or return to industry with a list of requirements drawn from both internal research and development (IRAD) efforts, Gayler said.

“JMR-TD are not rototypes, they are an experiment of technologies,” Gayler said at a recent Army aviation forum hosted by the Association of the U.S. Army at its headquarters outside Washington, D.C. “It’s going to inform what the final requirements will be. It’s really important … it’s the relationship of the attributes that are important to us.”

“Industry is certainly trying to provide an option, but what industry has right now is not a prototype,” Gayler told sister publication Defense Daily at the event. “It is going to be very informative to the final solution. I think we have to have that. We’ve got to have industry leaning forward. If industry listens to concepts and how we will fight and what combination of attributes will be important to us, it will only help them in the future.”

Gayler also said that FVL will not necessarily consist of one rotorcraft design scaled up and/or down to perform different missions, because certain airframe designs may not scale in the same direction.

“It is absolutely possible for us to envision different aircraft,” Gayler said. “We’re looking for the capability and the relationship of those attributes that provides the best capability in its class.”

“Though they could scale up, down, doesn’t matter,” he said. “It may not scale up better than the one that scales down. … I can envision the introduction of capability of several different variants that look distinctly different.”

Whether the Army would be able to martial the funding necessary to pursue two separate rotorcraft development and acquisition programs at once remains to be seen, Gayler said.

“The challenge is can you pursue those simultaneously? In today’s budget there’s no way without some significant adjustments,” he said.

The two competing designs – though they are not in direct competition yet – are Bell’s advanced tiltrotor, built on experience manufacturing the V-22 Osprey, and the coaxial-rotor technology developed by Sikorsky through its X-2 and S-97 experimental aircraft. Bell is a unit of Textron[TXT] while Sikorsky is now owned by Lockheed Martin [LMT].

Bell completed construction of its first V-280 Valor the week of Sept. 3 and is preparing for ground testing ahead of a first flight in fall 2017.

Sikorsky’s S-97 Raider, a smaller version of the SB-1 Defiant it has pitched for the JMR-TD program, has been flying for more than a year. One of the two existing prototypes suffered a hard landing in August, but the company said the mishap will not hinder the progress of the program, which is meant to validate the coaxial-rotor design.

The Defiant is based on the Sikorsky S-97 Raider, which employs coaxial main rotors and an aft pusher propeller to achieve the same fast-yet-maneuverable capability the Army desires.

The S-97 suffered “substantial damage,” according to a National Transportation Safety Board preliminary report on the Aug. 2 accident in Jupiter, Fla. The preliminary report was published Aug. 11 and shows that both pilots on board suffered minor injuries when the aircraft went down on a clear day while hovering.

The helicopter was recovered from the accident site and retained for further examination, the NTSB report said. Sikorsky plans to get its second S-97 airborne soon to resume flight testing.

Brig. Gen. Frank Tate, director of Army Aviation for the Army Deputy Chief of Staff, G-3/5/7, is closely watching both teams’ flight testing and is eager to continue working with industry to achieve FVL. However, he is focused on the capability certain technologies offer rather than the design of any specific aircraft, he said.

“We continue to look forward and work with industry to do relatively low-cost tech demonstrators, then demonstrate the validity of leap-ahead technologies that take the physics of vertical lift to a whole other level that we need to get to, to get after the capability gaps we have discussed,” Tate said.

“Then you close in on your actual requirements and put that out to industry, now knowing what is … achievable and get to more rapidly an actual product on the street,” Tate added. “We are focused on how we do our requirements process so we can do that much faster and do it in a way that is smart, that will get us what we want, that is not so constraining that you possibly throw away things that are achievable more quickly and are still a giant leap ahead.”