The first flight of the 787-9, the larger and potentially most popular version of Boeing‘s Dreamliner family, could come Tuesday morning, weather permitting.

Rain is okay, provided visibility is good. Boeing requires at least a 1,500-foot cloud ceiling for the test flight, which will take off from Everett’s Paine Field and land at Boeing Field in Seattle.

The 787-9’s debut offers Boeing a fresh start, a chance to get past the disastrous delays and troubles that bedeviled the first model.

And so far, this newest Dreamliner’s development has gone relatively smoothly and approximately on schedule.

It already features engine upgrades introduced since the original Dreamliner launch to reduce fuel burn.

The structural changes required to fix the flaw in the wing-to-body join that was discovered in 2009 during the 787-8 wing-bending ground tests were incorporated from the get-go into the 787-9 design.

Likewise, Boeing’s solution to the battery overheating problems that grounded the world’s 787s for three-and-a-half months earlier this year is already built into the very first 787-9.

If all goes well in the flight tests and certification process, which should last about nine months, the jet will be delivered to launch customer Air New Zealand next June.

The 787-9 is a 20-foot stretch of the initial 787-8 model with incremental structural enhancements to make it more efficient than the first Dreamliner.

As a result, it will carry around 40 extra passengers and has 23 percent more capacity in the cargo hold, and yet can fly about 350 miles further.

The model has already proved popular with airlines, with 388 firm orders. That’s more than 40 percent of total Dreamliner sales, which now stand at 936 firm orders.

Many analysts believe that this bigger model will be the biggest seller in the Dreamliner family and that many early 787-8 orders will eventually be upgraded to the -9.

While the wing size and overall systems design are unchanged from the first model, the 787-9 includes some subtle technological improvements that are almost invisible.

Structural and configuration changes have reduced weight and improved performance and fuel efficiency.

And the 787-9 tail has a proprietary aerodynamic enhancement that hasn’t been used in commercial aircraft before: Both the horizontal and vertical leading edges of the tail are dotted with pinprick holes that provide what’s called Hybrid Laminar Flow Control.

As the tail moves forward in flight, the tiny holes suck air into the interior of the tail structure, which then exits through a vent. This smooths the flow of air over the tail surfaces, greatly reducing turbulence and drag.

Boeing won’t give any details of the secretive manufacturing methods behind this technology. But back in 1988, then-McDonnell Douglas engineer Kenneth Perun filed a patent for a process that enabled laminar flow by using lasers to make the tiny, precise perforations in the titanium edges of wings and tail.

Boeing inherited that patent from McDonnell Douglas in 1997. Perun, now living in France, has been unsuccessfully petitioning Boeing for some recognition of his work.

All these small improvements in the 787-9 will now face intense real-world scrutiny as engineers montior performance during a vigorous flight test program, when pilots will push the airplane to extremes.

The second and third 787-9s are already in final assembly in Everett and will soon join the first in flight tests.

In 2010, the original 787-8 flight test program was abruptly halted for weeks when a serious fire broke out in flight, the result of a fault in an electrical panel.

Airlines will follow the 787-9 flight tests closely, hoping that this time Boeing can avoid such mishaps and anxious to see if the jet’s performance lives up to the promises.

(c)2013 The Seattle Times. Distributed by MCT Information Services.

Photo Credit: The first 787-9 completed taxi tests Monday in Everett in advance of the airplane's first flight. The Boeing Company / Flickr