F-22A #91-4008 makes the first GBU-39 SDB drop at supersonic
Photo: Lockheed / Kevin Robertson
7/17/2008 - EDWARDS AIR FORCE BASE, CA -- On July 11, the 411th
Flight Test Squadron passed a milestone as an F-22 Raptor travelling
at supersonic speed dropped a GBU-39 Small Diameter Bomb for
the first time.
The first supersonic SDB drop was part of a safe separation
test currently being performed to integrate the bomb with the
The SDB is a 250-pound class precision guided munition capable
of destroying high-priority stationary targets from Air Force
fighters and bombers from stand-off distances.
"An SDB has never been dropped from a supersonic aircraft,"
said Maj. Michael Starr, 411th FLTS test pilot. "Supersonic
separation testing will give the F-22 the ability to drop the
SDB at supersonic speeds, which synergistically enhances the
Raptor's air-to-air mission."
This was a critical step in achieving the goal of employing
a "fully operational small-diameter bomb," said Capt.
Chris Smith, 411th FLTS flight test engineer. The 411th FLTS
is planning on performing more supersonic drops as part of this
For safety purposes, the team based its test on a build-up
approach, gradually increasing the aircraft speed and altitude.
"At first, we had to make sure the aircraft could carry
the small-diameter bombs," Captain Smith said. "We
performed ground vibration testing to ensure that any conditions
wouldn't excite any structural modes of the F-22 and the bomb.
We also did three rounds of pit tests, where we placed an F-22
over a specifically designed stores separation pit and performed
numerous drops to verify safe separation of the bomb from the
aircraft and to ensure we did not structurally overload the
Performing ground testing ensured everything was in proper
order before performing separation testing in the air, said
Nicholas Chung, 411th FLTS air-ground weapons integration engineer.
"We started dropping small-diameter bombs from the F-22
at a speed of 0.8 Mach," Mr. Chung said. "We also
performed eight subsonic drops prior to this milestone."
Currently, the F-15E Strike Eagle is the only aircraft outfitted
with the SDB weapon system. Meanwhile, the F-22 carries two
1,000-pound Joint Direct Attack Munitions for its global strike
"Because of the size of the small-diameter bomb, the F-22
can carry more munitions at a time," Mr. Chung said. "Now,
we are looking at carrying eight SDBs compared to just two JDAMs.
This will allow the aircraft to strike up to eight targets at
The team is performing the testing at Edwards because it is
the only Air Force facility that performs developmental flight
test on F-22s.
"Edwards has the resources in terms of both assets and
test expertise," Mr. Chung said. "We really have an
emphasis not just on the technical aspect but also the safety
aspect of the testing."
Following a series of additional supersonic drops and after
the 411th FLTS determines safe separation of the bomb from the
aircraft, testers will begin dropping guided weapons, Mr. Chung
said. This is to determine not only safe separation of the SDB
from the aircraft, but also to see if pilots are able to guide
it to the target.
"This capability is essential to give the F-22 further
combat capability for the Global War on Terror," Major
"Through Herculean effort and incredible skill, the (411th
FLTS) engineers, flight test engineers, civilians and government
contractors did an unparalleled job showcasing the fact that
the F-22 Raptor is, and will remain, the world's most dominant
Source: USAF Edwards AFB Press Release by Senior Airman
Julius Delos Reyes