Hello again, CR4!
It's moorec74 back and ready for action.
As you may remember from my previous blog entries, I'm an aeronautical
and mechanical engineering major at RPI.
When people hear "aeronautical," they often associate my degree with
airplanes – but this isn't necessarily the case.
This semester, I've been taking a class called
"Rotorcraft Performance, Stability, and Control" to prepare myself for my
capstone project in the spring – so I've learned about helicopters far more
than airplanes. The main criterion that
distinguishes a rotorcraft from a regular airplane is that it is capable of
VTOL (vertical take-off and landing). Recently,
I researched the Black Hawk helicopter and found it so fascinating that I
thought I'd share a bit with you.
We
need more fire power!
In 1972, during Vietnam War, the United States
realized that it needed a more reliable and survivable attack helicopter to
perform military missions. The Pentagon proposed the UTTAS competition, or the
Utility Tactical Transport Aircraft System contest.
Sikorsky rose to the challenge and entered its Black
Hawk design into the fray. A prototype was built in 1974, and was selected as the
winner by the U.S. Army in 1976. The Black Hawk beat several innovative
designs, including Boeing's Vertol YUH-61. The Black Hawk, designated as the
UH-60, replaced the UH-1 Iroquois (the "Huey") and entered service in
1979.
The
Introduction of the Black Hawk
The Black Hawk is the military-model member of the S-70
family. Its purposes include but are not limited to the transport of troops,
electronic warfare, and aeromedical evacuation. There are many other variations
of this specialized helicopter for different uses. Some of the most common
variants of the Black Hawk include the Seahawk, Pave Hawk, and Jayhawk. Other
countries continue to use the design, too, including Columbia, Israel, Mexico,
and Turkey.
The UH-60L, the model that I'll discuss for the
remainder of this blog entry, can carry 14 troops or 6 stretchers with a crew
of two pilots. Empty, it weighs just
over 10,000 pounds; loaded, approximately 22,000 pounds. It can take off at a
maximum weight of 23,500 pounds.
The main rotor consists of four fully-articulated blades
with a standard swash plate. It includes elastomeric bearings and blade
dampers. The 53.67-feet diameter blades are made of titanium and fiberglass,
giving it a disc area of 2,260 square feet.
The tail rotor, designed to be a pusher type, also has four blades made
of similar materials.
Because it is meant to be carried aboard the C-130
Hercules airplane, the Black Hawk has a long, low profile so that it can fit
manageably. Its foldable tail boom and other easily-stored limbs make it an
excellent fit as well. The Black Hawk's fuselage (therefore not including the
rotors) is under 65-feet long, less than 8-feet wide, and stands just over 16
feet high.
 It's
a bird! It's a plane! It's a…Black Hawk?
While the Black Hawk can almost reach 160 knots, it usually
cruises around 150 knots. It can climb at a rate of 700 ft/min and with power
to mass ratio of 0.192 hp/lb. Its maximum range is also 1,400 miles, and has a
combat radius of 368 miles. It can climb as high as 19,000 feet.
Ready
for War
The Black Hawk has some intriguing mechanical features. Its
main landing gear system can absorb a crash landing of up to 38 ft/s. Its active vibration control system
mechanically generates vibrations that are out of phase with the main rotor to
decrease the noise felt at the hub of the blades. It has a ballistically-tolerant
flight control system, and its structure and drive system are obviously rated
for warfare. Every gearbox on the craft can even sustain flight for 30 minutes
without oil! (Imagine if your cars could
do that?)
The fuel system and pilot seating are very crashworthy;
valves, fuel lines, and fuel cells will breakaway from the helicopter to avoid
explosion. In case severe damage does occur during flight, the cockpit doors
are jettisonable – the entire doorframe will fall away from the vehicle if the
pilot believes it is necessary for survival.
And the Black Hawk's IHIRSS (Improves Hover Infrared Suspension System)
offers better survivability from heat seeking missile attacks.
And of course, it carries plenty of gun power. The Black
Hawk can hold machine guns, mini-guns, or gatling guns with an optional VOLCANO
minefield dispersal system. Stub wings
are located on the fuselage as an external support system. They can carry extra fuel tanks or more
armament, depending on the mission at hand - even rockets or laser-guided
missiles.
While airplanes are very appealing, I have found
helicopters (and particularly the Black Hawk) to be very interesting pieces of
machinery. I hope you have enjoyed this blog entry. Next semester, I'll be back
with my adventures of designing my own rotorcraft!
References:
Leishman, J. Gordon. Principles of Helicopter
Aerodynamics. Cambridge Aerospace Series. 2002.
"UH-60 Black Hawk."
Wikipedia. 2009.
http://www.sikorsky.com/
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Re: The Sikorsky UH-60 Black Hawk
