More than two years after opening its centerpiece display hall, the National Museum of World War II Aviation plans to begin construction on an expansion that will double the hall’s size as its celebrates its 10th birthday.

Site preparation began late last year on the 40,000-square-foot addition to the museum’s Kaija Raven Shook Aeronautical Pavilion with construction scheduled for this fall, CEO Bill Klaers said. The timetable will depend on fundraising — the museum has raised about a third of the $7.5 million needed to complete the addition, though new cost estimates on materials are not yet finished and could significantly increase the cost, he said.

“We have substantial commitments from foundations and other donors, but before we take that money, we want to make sure that we can start and finish the building,” Klaers said. “Our plans for phase two of the pavilion are the same as phase one — our exhibits are wrapped around a story line that is wrapped around the aircraft in our collection, and the story line for the next phase is already written.”

The museum, on the west side of the Colorado Springs Airport, opened in 2012 and will celebrate its 10th birthday in October. The facility houses 20 World War II aircraft, many of which are displayed in the pavilion, and emphasizes the key role aviation played during the war and afterwards, including the creation of the Air Force from what had been the Army Air Corps and the growth of airlines and the air cargo industry.

“We haven’t finished what we started — we still have more of the story to tell,” Klaers said. “The story starts with what the Army Air Corps looked like before the war started; we started out behind both Germany and Japan, but ended the war as the ‘Arsenal of Democracy.’ We talk about how long it took to train a pilot (one year) and what happened to them after the war — how aviation made the world much smaller.”

Klaers estimated construction on the addition would take about a year to complete and would make room to house more of the museum’s aircraft collection and other aircraft that donors would give to the museum if it had room to display them. Most of the collection had been assembled by Jim Slattery, the museum’s chairman and founder of a San Diego company that specializes in prescription drug monitoring, screening, and genetic testing.

Most of the collection of rare vintage aircraft was meticulously rebuilt by WestPac Services, a company Klaers started in the early 1980s near Los Angeles to restore World War II planes, that moved to Colorado Springs in 2009. The museum opened in adjacent hangars before moving to the pavilion, which is named for a major donor, when it was completed and opened in late 2019.

Another major expansion is planned after the addition is complete. The museum hopes to build a 86,000-square-foot Aviation Hall that will house most of the its interactive exhibits, visiting aircraft as well as an education center and event space. The hall, estimated to cost $31.5 million, would allow the museum to host larger meetings and events to generate revenue for its operation and education programs. Construction would start within three years of the addition opening and be completed two years later.

“We kind of started backwards because the need came up to house the aircraft that had been donated to the museum,” Klaers said. “Once the aviation hall is built, you will enter the museum through that building and then go through the pavilions to see the aircraft, and all of the educational programs now housed in the pavilion will be moved to new education center attached to the hall.”

The pavilion had been open just a few months when a state stay-at-home order designed to slow the spread of the COVID-19 pandemic forced the museum to shut down for more than three months and then operate with capacity restrictions for much of the rest of 2020. However, the museum rebounded last year, attracting 44,000 visitors and hosting several large events to help generate revenue, Klaers said. The facility also sponsors monthly lectures and fly-in events that attract up to 700 visitors.

“If you take out 2020 due to the COVID restrictions, we reached the first-year visitor forecast in the market and feasibility study Summit Economics had conducted for us,” said Mark Earle, a member of the museum’s board of directors. “We are on track with those forecasts, and that study calls for 90,000 visitors by 2027, when we expect to be in full operation with all of our facilities. We expect we will exceed those projections.”

The museum plans to expand its operations in April from 10 a.m.-5 p.m. five days a week to the same hours six days a week and add a seventh day of operations in May. The board plans to maintain that schedule until November, when the museum would return to five-day-a-week operations for the winter months. To accommodate that expansion, Earle said the museum is recruiting additional volunteers beyond the 160 volunteers that now serve as its primary staff.

Admission charges for the museum are $17 for adults, $15 for seniors or military personnel and $12 for children ages 4-12 with discounts available for prepayment. World War II veterans are admitted free. The admission charges help to support the museum’s education programs, which use stories from the museum’s exhibits to get children interested in aviation and careers in science, technology, engineering and math (STEM).

The museum plans to host Pikes Peak Regional Air Show Sept. 24-25 featuring the Air Force F-35A Lightning II Demonstration Team, aircraft from the museum’s collection and other vintage aircraft. The event, which will be similar to the 2019 version of the same show, will benefit the museum as well as the Peterson Air & Space Museum at Peterson Space Force Base and the 4th Infantry Division Museum at Fort Carson.