Airplane programs traditionally began in one of two ways: either as a conceptual design, such as the Eclipse 500, which the manufacturer used to drum up deposits for future sales; or as a proof-of-concept prototype (POC), which is basically a full-size flying model airplane designed to show off the design’s attributes, and whose would-be manufacturers are also seeking deposits.

A POC is risky, however, because it doesn’t usually take into consideration the reality of certification and volume manufacturing. The prototype might perform and fly similarly to the final product, but under the skin the finished airplane is vastly different, with certifiable systems and structure backed up by stacks of paper confirming test results, all with an eye toward bringing a product to market.

Lately, manufacturers or would- be manufacturers have adopted what they are calling the “concept” airplane, a product intended to gauge the potential market. At last year’s NBAA Convention, Cessna unveiled what it calls the Large Cabin Concept (LCC) jet, although only in fuselage mockup form. The LCC was followed by the Eclipse Concept Jet (ECJ), a sporty-looking V-tail jet single that was flown to this year’s EAA AirVenture show in Oshkosh. The ECJ was displayed on a revolving platform, just like a concept car at an auto show.

The purpose of a concept airplane is to test the marketplace to see if there is sufficient interest to warrant spending the hundreds of millions of dollars needed to bring a business jet to market. Cessna has been evaluating feedback on the proposed LCC for more than a year and expects to launch the large jet shortly; Eclipse says that market response to the ECJ is phenomenal. Embraer too has adopted the concept jet, revealing two new proposed business jets at this year’s NBAA Convention in late September. The MLJ (midlight jet) and MSJ (midsize jet) would fill the gap between Embraer’s Phenom 300 light jet and Legacy 600.

Fielding a concept jet can be cost-effective. Cessna and Embraer spent some money on preliminary engineering and built fuselage mockups, and Eclipse went to the trouble of building an entire, flyable airplane. In building the ECJ, the company was able to use a flight-test engine from its Model 500 program as well as wings, the forward fuselage and most systems and avionics. Eclipse pulled off the first flight of the ECJ in just seven months. Epic also brought a single-engine jet–the Victory–from design to first flight in little more than six months, but Epic doesn’t apply the word “concept” to label any of its airplanes. The Victory is more accurately a prototype, not just for a future certified version but also for an amateur-built program that will let buyers build their own Victory or Dynasty (single-engine turboprop) or Elite (twinjet).

If the concept airplane proves to be a useful tool, expect to see more of them as the business aircraft market continues to fill into every niche imaginable. Not all concepts will make it to market, but that’s the whole idea. The less money spent up front, the more that is available for the hugely expensive and time-consuming certification and production ramp-up programs.