Thursday, November 6, 2014

Build-Your-Own Aircraft: SR-71 Blackbird! (Aerospace Education #1)

By 2d Lt Karin Hollerbach, photos by 1st Lt Pat Bitz

Airplane parts.
On 14 October, 1st Lt Pat Bitz held the first in a series of Aerospace Education classes.  In this class, participants built a simple model SR-71 Blackbird reconnaissance aircraft from everyday household materials and objects.

1st Lt Bitz, photo by
Lt Col Juan Tinnirello

Airplane builders hard at work.
Lt Bitz talked about the functional pieces of the model the class was building – including wings, engines, and stabilizers. Then participants worked from a template, traced and cut out control surfaces from a Styrofoam dinner plate, and assembled the fuselage and engines from foam tubes normally used to insulate hot water pipes using a hot glue gun.  A clever bit of rubber band and wire-ties allowed the aircraft to be reusably launched and recovered using human power. Most were able to fly their creations for across-the-room distances.

Comparing design variations.
The second class in this 6-part series will be held at Squadron 188’s headquarters at Oakland Airport on Tuesday 11 November. Members of other squadrons are welcome to participate.

Blackbirds were used for their advanced photographic and electronic sensor systems, which collected intelligence for the Air Force and other federal agencies from the late 1960s through the 1980s.

The following information is extracted from a NASA factsheet about the SR-71:

Still hard at work!
The Blackbird design originated in secrecy during the late 1950s with the A-12 reconnaissance aircraft that first flew in April 1962 and remained classified until 1976. President Lyndon Johnson publicly announced the existence of the YF-12A interceptor variant on Feb. 29, 1964, more than half a year after its maiden flight. The SR-71 completed its first flight on Dec. 22, 1964. More than a decade after their retirement the Blackbirds remain the world's fastest and highest-flying production aircraft ever built.

Almost done...
The Blackbirds were designed to cruise at Mach 3.2, just over three times the speed of sound or more than 2,200 miles per hour and at altitudes up to 85,000 feet. The extreme operating environment in which they flew made the aircraft excellent platforms for conducting research and experiments in a variety of disciplines: aerodynamics, propulsion, structures, thermal protection materials, high-speed and high-temperature instrumentation, atmospheric studies, and sonic boom characterization.

Finally… airplanes! 
Two Pratt & Whitney J58 axial-flow turbojets with afterburners, each producing 32,500 lb of thrust, powered the Blackbirds. Less than 20 percent of the total thrust used to fly at Mach 3 was produced by the engine itself, however. During high-speed cruise conditions the balance of total thrust was produced by the unique design of the engine inlet and a moveable conical spike at the front of each engine nacelle. Under these conditions, air entering the inlets bypassed the engines, going directly to the afterburners and ejector nozzles, thus acting as ramjets.

The airframes were built almost entirely of titanium and other exotic alloys to withstand heat generated by sustained high-speed flight. Capable of cruising at Mach 3 continuously for more than one hour at a time, the Blackbirds provided a unique research platform for thermal experiments because heat-soak temperatures exceeded 600 °F.

Blackbirds being tested.
The aircraft was 107.4 feet (32.73 meters) long, had a wingspan of 55.6 feet (16.9 meters), and stood 18.5 feet (5.63 meters) high (from the ground to the top of the rudders when parked). Gross takeoff weight was about 140,000 lb (52,253 kilograms), including a fuel weight of 80,000 lb (29,859 kilograms).

Aerodynamic control surfaces consisted of all-moving vertical tail fins above each engine nacelle and elevons on the outer wings and trailing edges between the engine exhaust nozzles.

Additional information about the SR-71 Blackbird can be found at the following links:
YouTube videos of Blackbird flights
NASA gallery pictures of the Blackbird

Class #2 – Tuesday 11 November – 7 PM at Squadron 188
Build and Launch:
1.  AlkaFuji rocket - aka "Fizzy Flyer"
This activity illustrates Newton's Laws of Motion.

2. Build -"The Goddard Rocket"
We will introduce Dr Robert Goddard, the man who pioneered liquid propelled, controlled rocket flight, and build a flying model of his 1931 rocket.

Take home two rockets, then re-launch with your family and friends demonstrating Newton's Laws.

No comments:

Post a Comment