Designed as a plane that can take off straight up and then fly at 700 miles per hour, the craft has never attained a height of more than a few feet in prototype tests before crashing to the ground.
"There have been four accidents in the last four years," says Congressman Brad Miller, D-N.C. Miller, chairman of the Subcommittee on Investigations and Oversight of the Committee on Science and Technology, will hold hearings on the troubled project tomorrow morning. "The good news is that when it crashes, it only crashed from a foot or two off the ground."
Pentagon documents obtained by the Blotter on ABCNews.com show military analysts have consistently rejected the craft since 1986 as technically flawed.
"We quickly reached a conclusion with substantiation that it was not worth pursing at any level for any amount of money," said John Eney, a retired Navy analyst involved in the initial rejection.
"What they have now has become the laughingstock of the southern California aviation industry," said Eney, who is slated to testify tomorrow before Miller's committee. "I'm embarrassed as a taxpayer and as a 35-year veteran of Naval aircraft engineering."
But the rejection by Pentagon experts did not stop Congress from continuing to pour money into the program, under prodding from San Diego-area congressmen, including Duncan Hunter and Christopher Cox, now chairman of the Securities Exchange Commission.
"They've been the two most consistent supporters," said Anthony DuPont, the president of DuPont Aerospace, the company which designed the craft. DuPont is also scheduled to testify at tomorrow's hearing.
DuPont said Cox, after college, "actually worked on the airplane as an engineer."
Both Cox and Hunter have received substantial campaign contributions from DuPont and others at his company, not connected with the giant chemical company of the same name.
Cox received $18,000 in contributions, according to campaign finance documents reviewed by ABCNews.com. Cox now says the project should have been abandoned. "What I supported was doing the testing to determine whether it could fly. As soon as it failed to meet the test criteria, the plane should have been abandoned," Cox told ABCNews.com.
Hunter has received at least $36,000 from DuPont for his past congressional campaigns and current Republican presidential campaign.
DuPont says his contributions are not connected to the continued support he has received for his project.
Hunter for President bumper stickers can be seen on cars parked in the DuPont Aerospace parking lot at an airport outside San Diego.
Hunter also denies the campaign contributions have any connection with his continued support of the aircraft. He says he makes "decisions on what I think is right for the country" and that he has rejected other projects backed by large campaign contributors, like General Dynamics and Boeing. A congressional source confirmed to ABCNews.com that Hunter is expected to testify at tomorrow's hearing.
Hunter says many of the most important technological advances have been initially rejected by the Pentagon, citing his support for the "X-craft," a new Navy boat that can travel over water at 60 mph.
"The Pentagon does a lot of good things, but they miss some things," Hunter told ABCNews.com.
An animated video produced by DuPont Aerospace shows the craft taking off vertically with 50 troops on board and then flying at 700 mph into Tehran.
"We need to put more money in it, not less," said Hunter. "I think it's very promising technology."
Employees at the San Diego airport, where the prototype of the craft is stored, are not so sure.
"They do fire the engines up, and it moves around the airport -- but on the back of a truck," said a flight school instructor.
DuPont says he has permission from the Navy to continue testing the craft and will do so soon.
This post has been updated.