Historic GALCIT 10 Foot Wind Tunnel to Close Its Doors After 68 Years of Service

Gerald Landry, 3 March 1997

The historic GALCIT 10 Foot Wind Tunnel at Caltech ends its operation after 68 years of service to numerous aircraft and automobile companies, as well as many government agencies and other private sector businesses.

Caltech receives $300k for aviation

A newspaper article dated August 1926 states that the Daniel Guggenheim Fund provided a gift to Caltech to establish the Guggenheim Laboratory of Aerodynamics and Aeronautical Engineering. Dr. Robert Millikan, then President of Caltech, approached the Guggenheim Foundation to request the funding for the new school of aeronautics.

Ground breaking for new school of aeronautics

May 1927 saw the ground breaking for the new Guggenheim Aeronautical Laboratory building and wind tunnel. The building and the wind tunnel were built at the same time, but on independent foundations. In an effort to save space, the wind tunnel was built vertically and housed within the new structure. The wind tunnel required a space 46 feet tall, 100 feet long and 25 feet wide. At one time, the wind tunnel and its balance and run systems took up most of the five floors of the new building's south side.

By November 1929 the building and wind tunnel were ready to begin their lives together. Many months were required to get all the machinery in working order, as well as completion of the velocity surveys, energy ratio runs, "tuning" of the air path to reduce turbulence, and balance the propellers. The work was accomplished by a number of faculty and staff members. The list of members included professors Theodore von Karman, the "father of aerodynamics," Clark B. Millikan, A. L. (Maj.) Klein, William H. Bowen, Ernest E. Sechler and W. Baily (Ozzie) Ozwald.

During this time, the new balances were being designed and built on campus for the new wire rigging system. The new electro-mechanical balances consisted of a moving poise weight driven by malt machine motors, via a lead screw. The balance beam was pivoted on knife edges by the aerodynamic forces acting on the wire rigging system that was attached to the airplane model in the working section of the tunnel.

By November 1930, the first of over eleven-hundred commercial tests was ready to begin. A page out of Bowen's notebook, dated 1 November 1930, reads: "Installation of the Goodyear Air Wheel for gross drag determination (16 hours)." This first test was run from 5 November through 11 December 1930. In noting the dates listed for work accomplished during this period, it appears that these men were working seven days a week.

Concrete and steel, with some wood thrown in for sound deadening

Concrete and steel were the primary materials used to build the new tunnel; however, a 37 foot section of the upper leg which includes a portion of the venturi, working section and diffuser were constructed of wood with steel staves. The wood used in this section was 2" thick redwood.

Not often seen in newer wind tunnels, the GALCIT 10 Foot Wind Tunnel was circular throughout. The internal dimensions varied from the 10' diameter working section, 12' diffuser, 15' fan section, and the 20' settling chamber, with a 4:1 contraction ratio.

Turning vanes are located at each of the four corners of the tunnel circuit. These vanes help direct the air flow within the tunnel. The turning vanes located at the west end of the circuit also served as cooling vanes. These vanes once had water flowing through them. This would draw off the heat generated by friction and the big electric submarine motor.

Submarine powered

An electric 750 horsepower prototype WWI submarine motor built by General Electric powered the big wind tunnel throughout its life. Originally, the ex-submarine motor and a four-bladed wooden propeller drove the wind velocities up to 200 mph in the working section. Propeller configurations changed many times over the years. Beginning with four blades, changes included three blades, six blades, and back to three blades.

At the time of decomissioning, a three-bladed propeller was in use. Maximum velocities of 160 mph were the norm. Each of the blades in the last propeller was made of aluminum, and weighed 190 lbs. That's a lot of mass in motion at 800 rpm. During a test in 1962, while running at maximum velocity, the propellor hub failed, allowing various pieces of hub and blades to find new resting places. It has been said of that incident, "The shaking was so bad that the Seismology Laboratory registered it as a small local earthquake."

First complete airplane model to be tested at the new GALCIT wind tunnel

On 18 December 1930, the installation and testing of the first complete scale airplane model was about to begin. GALCIT Wind Tunnel Report No. 102 made history. This was Northrop Aircraft Company's first all metal, stressed skin monoplane. The new airplane was to be named the Northrop "Alpha." Extensive wind tunnel time was spent developing wing fillets, as well as the "pants" to streamline the fixed landing gear. This six passenger airplane was later sold to TWA Airlines and the U. S. Army. An example of this airplane hangs from the ceiling of the Smithsonian Institution's National Air and Space Museum. The "Alpha" model was donated to Caltech's aero department for future studies. The model was in storage at Caltech for many years, and returned to Northrop's Western Museum of Flight in Hawthorne, California, eight years ago. It has been restored by the museum staff, and is displayed in a place of honor at the museum.

Wind tunnel declared ready

A statement from William H. Bowen's notebook, dated 20 January 1931, tells the news: "Tunnel turned over to Aero department as in condition to operate." It took many long hours, by many dedicated people, to bring the wind tunnel to a productive life.

Rigid airships to be tested at the GALCIT tunnel

Installation of the airship model "Akron" began on 24 July 1931. Goodyear-Zeppelin Company was to design and build two airships for the U. S. Navy. They would be known as the ZRS4 Akron and the ZRS5 Macon. Wind tunnel tests were still being conducted at the GALCIT facility when the Akron made its maiden flight on 23 September 1931. The design of both airships was unique in that it provided internal space for five airplanes that could be launched and retrieved while the airships were in flight.

Both airships met untimely ends. The Akron was lost in a storm over the Atlantic on 4 April 1933, and the Macon, which first flew on 21 April 1933, crashed in the Pacific on 12 February 1935.

The First Decade

The wind tunnel's first ten years proved its usefulness. Test activities resulted in som 287 separate reports. Of these, 19 were research papers by faculty and students. The following is a list of users of the facility in the early years and into the fugure: Aireasearch, Airover, Airplane Development Corporation, Bendix, Boeing Aircraft, Consolidated Aircraft Corporation, Crosby, Curtiss-Wright, Davis, Douglas Aircraft Company, Fokker, Goodyear-Zeppelin, Goodyear Tire and Rubber Companies, Hughes Development Company, Lobil, Lockheed Aircraft Company, Martin Aircraft Company, National, North American Aircraft Company, Northrop Aircraft Company, Odor, Svenska, Transair, Vultee Aircraft Company, and Zap. This is an impressive list of names; unfortunately, most of them have been lost to history.

World war

WWII found the tunnel and her staff ready, willing and able to perform yeoman service in the development of a wide range of much needed military aircraft. The wind tunnel staff were stretched to the limit. Seven day weeks, up to three shifts a day. There was a need for many more people now. During this period of national crisis, the wind tunnel employed up to 60 people. These were the cream of the crop in a variety of disciplines. GALCIT's students were also involved. Many of our alumni worked in the wind tunnel during this time. These women and men provided a much needed service.

Army Air Corps, and U. S. Navy personnel were also being trained at GALCIT during these years. Along with their classes, they accomplished hands-on engineering by working at the wind tunnel.

Over 47 different aircraft and their variants were developed and tested at the wind tunnel through the end of the war. During that time, early jet aircraft were also under development. Aircraft types ranged from trainers, pursuit, and amphibious to medium and heavy bombers. The list of aircraft is quite long. Some of the better known were: B-17 Flying Fortress; B-29 Super Fortress; C-47 Commando; C-47 Dakota; DC-1 through DC-4; A-20 Boston; B-24 Liberator; P2V-1 Neptune; AT-6 Texan; B-25 Mitchell; P-38 Lightning; P-51 Mustang; P-61 Black Widow "night fighter."

New model suspension system required for quick model changes

With the war years upon us, and an urgency to develop high performance aircraft, there was a need to develop and build a new rigging system. Theodore von Karman selected A. L. (Maj.) Klein and Peter van Horn Serrell to design the new system.

By August 1941, the new system was ready. This system allowed model changes to take place in a minimum of time. The work load required this. Time was of the essence if we were to stay ahead of our enemies. The new system used rods, links and flexures to transmit the aerodynamic loads to the existing balances, rather than wires. This system proved to be very reliable and strong. One of the problems with the wire system was if a wire was put in compression, typically the model would break loose and fly down the tunnel to destruction. With the new system, this problem was eliminated.

Hundreds of aircraft were tested using this new rigging system, including the Douglas DC-6 through DC-10, and the HK-1 Spruce Goose. Other items included ship antennae, street lighting fixtures, automobiles, motorcycles, parachutes, missiles, projectiles, and even 2x4s and water pipe over the tunnel's 46 years of service.

October 1987 brought an end to the rigging and balance system. An earthquake centered in Whittier rolled through at about 6:55 a.m. This was not the first earthquake the wind tunnel had experienced; however, it was one of the most destructive. I weathered the initial shock at the corner of Hill and California. I was standing at the foot of the north platform ladder when the first aftershock hit. Although there must have been a lot of noise around me, I didn't hear a thing. I was watching the wave go through the building and wind tunnel. My vision was so overwhelmed by the activity that my hearing must have shut down. The wind tunnel looked like an inchworm, bending and rolling with the wave. I've never seen anything that big move that much and not break. It was easy to understand why the rigging was destroyed. Broken parts were everywhere, as was oil from the dashpots holding the counterweights.

The system sustained $50,000 of estimated damage, and funding was not available for repairs due to the overall effect campus wide. The system was removed in 1990. The wind tunnel was no longer in the airplane business. It was the end of an era.

Rocket and jet aircraft development begins in 1944

With the development of the jet engine, new airplanes were on the drawing boards. The future would be fast and noisy. Although the early jet airplanes were fast, there was at least one propeller driven airplane that could outmaneuver and out fly most of them. This was the latest version of the P-51 Mustang. As with most things given the opportunity to evolve, they get better and faster; however, the P-51 still holds people spellbound when they are near.

Early rocket planes under development at the wind tunnel included the Douglas D-558-I Skystreak and the D-558-II Skyrocket. Early jet aircraft included the Douglas XB-43, Consolidated Vultee XB-46, and Convair Aircraft XP-92 Delta Wing Airplane.

Post war and beyond

Aircraft development continued to be the mainstay of the wind tunnel right up to the 1987 earthquake; however, others felt the wind tunnel could be very useful in developing more aerodynamic and stable automobiles. With that, we began a long-term relationship with General Motors in 1953 with the testing of early Corvettes. As time went on, more and more car companies joined in the search for more efficient and aerodynamically stable cars. Our contractor list reads like a who's who of automobiles. We have had long-term relationships with not only General Motors, but with Honda, Nissan, Toyota, VW America and Volvo.

We have been involved in the development of speciality vehicles, such as the Sunraycer solar electric car, GM Impact and EV-1 electric cars, Volvo's ECC hybrid electric car, Summers Brothers land speed record car, Demi Electrics electric land speed record car, Safety Vehicles, Delorean, the Bill Freeman Can-Am car, as well as the development of many racing motorcycles.

A wide variety of other vehicles and items have also been tested in the Ten Foot Wind Tunnel over the years. These include: Super tankers; war ships; sail boats; trains; trucks; external aircraft stores; rubber wings; scaffolds; radio telescopes; deep space network antennae; tow flags and targets; motorhomes; drone aircraft; gliders; Deep Submersible Rescue Vehicle; life rafts; street lighting; freeway barriers; Olympic bicycles; buildings and building clusters; soap box derby cars; stack gas flow; Venus Probe; sea-based oil drilling platforms; baseball and football stadiums; wind mills; wind turbines; water turbines; airport towers and radomes; aircraft landing skis; Olympic luge with rider; speed skiers; and various Mattel toys.

The wind tunnel has also been sought out for inclusion in the making of commercials; the PBS film "The Plane that Changed The World," The 50th anniversary of the DC-3; a bicycle safety film; Life Magazine Olympic bicycle shoot; ABC's Nightline "Hurricane Hugo;" Merlin Olsen's TV program on hurricanes; and most recently, Huell Howser's "California Gold" for PBS.

With such a varied diet of work, one would find it difficult to become bored with this job. I have found my job of 24 years at the wind tunnel to be very rewarding and satisfying in many ways. Where else could you work with such a diverse group of people? I have interacted with many students, faculty and staff at the Institute, as well as all of the different groups of outside contractors from many companies and government agencies. All of these people have left their mark. They have educated me, helped me, given me support when needed, and most have given me a reason to smile. I could not have asked for a nicer group of people to be with all these years. The work at the wind tunnel has been, in a word, "rewarding." Since August 1985, the wind tunnel has been a one-person operation for the most part. Being the last one to operate such a historic test facility as this, also leaves its mark. It is with a great deal of sadness that I watch this facility go. Those things that will bring back the smile are remembering the tours of the facility with the young and old school kids, girl and boy scouts, VIP visitors from local and foreign governments, visitors from Japan, China, Germany, Russia, Australia, Hawaii, Taiwan and Africa.

Most of the people I take on tour of the wind tunnel turn into kids. A walk through the wind tunnel circuit does that to people. Some can't get enough of it and come back for seconds. The small children don't miss a thing. They seem to thoroughly enjoy the time they spend going through the place, and they ask some really good questions that keep me on my toes.

A special thanks to all who have made this job special to me.

The last test was conducted on 25-26 February 1997. The power will be turned off on 7 April 1997, and on 30 April we will have a formal decommissioning ceremony with a fly-by of vintage aircraft. Demolition begins 16 June.