Interesting research. Flatau and the guys who worked with/for him at Edgewood Arsenal and Guilford are an interesting topic. Below are the quotes I found in your link. I have seen the Flatau airfoils in 45 ACP and in 40mm (grenades) and discussed both with the guys at Edgewood in the mid-1980s (hoping to find that they made airfoil loads in 9x19mm-answer was “no”) but had not heard of the RAP loads. If there were 500K made some should have shown up somewhere. Does anyone have a photo?
"TITLE: TechBeat Winter 1998
Subject: Technology, Law Enforcement, Police
Published: January 1998
NIJ Takes the RAP
It was the late 1960s, the era of the Vietnam War,
and Abraham Flatau was an aeronautical engineer
working for the U.S. Army, a young man full of
energy, curiosity, and bright ideas. He knew the
soldiers in Vietnam were having problems with
their rifle-fired grenades. Their grenades
required a high trajectory, which made them
impossible to use in the thick canopy of the
jungle. The heavy foliage invariably caused them
to blow up short of their target.
Flatau knew the solution was a projectile with a
flat trajectory, something that would fly straight
and fast, without the typical ballistic arc. He
also knew there were only two methods to achieve
this flat trajectory: increase muzzle velocity or
find a way to create aerodynamic lift in the
projectile. His solution lay with the latter
method. The result was the ring airfoil grenade, a
small explosive metal ring that looked like a
donut and spun like a bullet. Because it generated
lift while it flew in a low-drag mode, it had a
near straight-line trajectory. Flatau’s theory was
sound enough that a prototype was developed.
However, the Army never pursued it.
It was not until the 1970s, following the
shootings at Kent State University, that the
subject of the ring airfoil grenade came up again.
Like many law enforcement and military officials,
Flatau saw a need for a nonlethal device that
would give military police and law enforcement and
corrections officers more control over crowds
without the possibility of killing anyone.
Many of the crowd control devices at that time–
rubber and wooden bullets, for the most part–had
serious problems. They had to be skip-fired
(ricocheted) so they would hit people in the legs,
not in the head. This meant that even the smallest
piece of gravel or rock could bounce the
projectile in the wrong direction. At long range,
these weapons were disturbingly inaccurate, and at
short range, they could be lethal.
Flatau had the solution. He turned his explosive
ring airfoil grenade into the nonlethal ring
airfoil projectile (RAP), a 2-inch-diameter rubber
ring weighing about 1 ounce and banded with a
special paper wrapping designed to hold the shape
until impact. It was fired by a launcher-adapter
that fit over the barrel of an M-16A1 rifle and
propelled by a 5.56mm low-grain blank cartridge.
The RAP flew at 200 feet per second, spun at 5,000
revolutions per minute, and delivered about 39
foot-pounds of energy. Flatau created two
versions: the sting RAP and the soft RAP.
The sting RAP was of particular interest to
military police, who requested that it be accurate
enough to hit a man-sized target from 40 to 50
meters, just outside of rock-throwing range, and a
group of three people from 60 meters. Because one
sting RAP could be used repeatedly, simply by
rebanding it, it looked like a financially
feasible tool, whether it was used for crowd
control, in hostage situations, or as a training
device. The sting RAP has the potential to stop a
person, cause him to drop a weapon, or deter him
temporarily to buy time for officers to respond to
the situation. Biophysics testing showed the RAP
could not break bones or injure internal organs,
no matter how it was fired. It could, however,
break double-pane glass, which was an advantage if
one had to hit a subject inside a building.
Ironically, although the sting RAP was approved
for military use, it was never used. The Army
produced 500,000, but then left them on the
shelves where they remained for more than 15
years. The second version, dubbed the soft RAP,
offered a little extra punch–it had 18 cavities
embedded with tear gas that was released on
impact, but it was never produced.
Enter Lt. Col. Matt Begert, who specializes in
finding new technologies for the U.S. Marine
Corps, including information on nonlethal weapons.
It was during his research that Begert learned
about Flatau’s invention. And while making a
presentation on promising new technologies to a
group of research and development personnel,
Begert mentioned the ring airfoil grenade and its
more modern incarnation, the RAP. To his surprise,
Flatau was in the audience. Begert and Flatau
later got together, took the device off the Army’s
shelf, and fired it. It worked perfectly.
“It is as less-lethal as you can get,” Begert
says. “You can fire it pointblank and it won’t be
lethal. It won’t knock you down, and it’s round
[donut shaped, larger than an eye socket], so it
can’t poke your eye out. What it will do is get
your attention, and on some people, it will leave
In 1997, the RAP came to the attention of the
National Law Enforcement and Corrections
Technology Center (NLECTC)-West in El Segundo,
California, where Begert and Flatau demonstrated
it to law enforcement and corrections officers. It
made such an impression that the National
Institute of Justice (NIJ), as part of its
continuing search for viable nonlethal devices,
has funded research into updating and adapting the
RAP for use by corrections and police agencies. A
grant to Guilford Engineering, of Guilford,
Connecticut, is expected to produce several
things: designs for a handheld, stand-alone RAP
launcher that will not look like a deadly weapon;
the development of a soft RAP embedded with
oleoresin capsicum (OC) that will release a 3- to
4-foot cloud on impact; and a design for a
pistol-like configuration such as a flare
“This whole thing is going to be an engineering
feat. The device is elegantly simple, but these
new designs are going to be a lot of work,” Begert
In the interim, existing RAPs have been taken off
the shelf and are being tested by three agencies.
The Los Angeles County Sheriff’s Department plans
to demonstrate and possibly employ them
operationally. The Federal Bureau of Prisons has
obtained some for testing, as has the Royal
Canadian Mounted Police.
For more information about the ring airfoil
projectile, contact Sandy Newett at the National
Institute of Justice, 202-616-1471."