Boeing Philadelphia Wind Tunnel Modernization Project
Ridley Park and Eddystone, PA

The Boeing Rotorcraft facility in Ridley Park and Eddystone, PA is the one of the largest employers in Delaware County.  The site produces Chinook tandem rotor helicopters for the U.S. Military and numerous foreign customers, and in a joint program with Bell Helicopters, manufactures the fuselages and other portions of the V-22 Osprey.  This Boeing site also is involved in engineering activities for other aircraft and technical developmental projects.
In 1968 Boeing constructed a 12 Megawatt (16,000 HP) subsonic wind tunnel at their plant in Eddystone, PA. A wind tunnel is an Aerodynamic Development Tool that is used to produce winds at varying speeds within a closely controlled environment.  The Philadelphia Wind Tunnel is truly impressive.  Forty-two tons of air, driven around the 900 foot circuit by a 40 foot diameter, 12 MW fan, approach speeds of 250 mph at the 20 foot x 20 foot test section.  The Boeing Vertical and Short Take-off and Landing Wind Tunnel (BVWT) is a “jewel” in our local economy. It is the largest, privately owned, subsonic wind tunnel in the United States.

The BVWT has directly affected the lives of everyone in the United States. Anyone who has flown on a Boeing aircraft can find a link to this wind tunnel. The BVWT has been used to develop military aircraft that have kept the USA secure; has saved energy by modeling aircraft and vehicles to optimize design, increasing efficiency and minimizing fuel consumption; and it may be used in the future for developing wind energy, lessening our dependence on fossil fuel.

Scale models of helicopters, military aircraft and commercial jets as well as full size vehicles such as automobiles are placed in the test section where instruments record the effects of wind moving over and around a solid object. Uniquely constructed to be a versatile aerodynamic development tool, the BVWT tests fixed wing, rotary wing and ground effects vehicles. The facility is available for contract work to outside organizations.

Construction of the wind tunnel in the latter half of the 1960s was a major addition to technical and commercial capabilities available in the Delaware Valley. Its construction was highly publicized within the engineering community and at engineering colleges. Since it was constructed, the only major modification to the infrastructure of the tunnel prior to this project was the installation of honey comb flow straighteners to improve air flow quality.

The BVWT fan motors, bearings and shaft are located in an aerodynamically shaped nacelle chamber, which is supported by aerodynamically shaped stators (struts). The nacelle chamber is centrally located on the opposite side of the circular tunnel from the test section. Nine, original, custom made wooden blades are connected to the fan shaft.  A 13,200 Volt, 9,600 HP Wound Rotor Motor and a 600 Volt, 1000 HP DC motor were located within a nacelle chamber.

The electrical equipment was original, obsolete, becoming unreliable, and utilized parts that were no longer available.  Increasing, decreasing and accurately controlling the speed of a 40 foot diameter fan was a technical challenge 40 years ago as it was on this project.  The old technology utilized both the DC motor with a DC Drive and the wound rotor motor with a liquid rheostat for speed control. 

This project replaced the old motors, couplings, controllers and control systems with new state of the art technology and evaluated, but did not, replace the original fan shaft bearings. This project also renovated and modernized the BVWT control room.

Once existing equipment was demolished, there was no possibility of putting the wind tunnel back into service. A mistake in the engineering or construction on this project would not only affect The Boeing Company, but could also destroy the unique ability to perform subsonic aerodynamic testing for numerous other customers. 

A key technical requirement of this project was to replace the motors, bearings and couplings and their associated motor controllers, cooling systems and lubricating systems without disturbing the precise alignment of the fan with its wooden blades and the nacelle chamber.

Choosing to use the latest state of the art technology and deciding on a 18 MW (22,000 HP), 6,600V variable frequency drive (VFD) with the serial number “009,” presented technical opportunities and challenges to the manufacturer and engineers.

Engineering for this project required rethinking and redefining how the fan would be powered and controlled with the goal of providing a new motor and drive system that would have quicker acceleration and deceleration times and ultimately had more power.  Engineering work included:

Some of the major technical and construction constraints included:

The new equipment includes:

The new BVWT system is capable of a peak power of 22,000 HP.  To put this into perspective, that is enough power to light almost 22,000 homes, enough power to provide 5.9 watts per square foot to the Empire State Building, 13.1 watts per square foot to the Comcast Building; or 13.6 watts per square foot to the One Liberty Place building,

The new drive system is in operation and working well.  The project was performed within budget and on schedule.  Some of the major benefits achieved by this project include:

LaSalle University Pedestrian Bridge/West Campus Expansion Project
Philadelphia, PA

LaSalle University, located in the West Oak Lane neighborhood of northern Philadelphia, has had an increasing student enrollment as a result of the expansion and growth of its programs over the past twenty years.  A recent particular need was recognized to expand and modernize the University’s science and technology programs to allow it to remain competitive in these areas.

As a first step in this process, Holroyd Hall, the current building dedicated to the science departments, would be completely renovated, updated, and expanded with an 8000-square foot addition of new laboratory and classroom space, to become the new Science and Technology Center.

The University’s nursing program is undergoing a similar transition.  It will be moved into new space in a building that was part of the former Germantown Hospital complex.  This complex is located adjacent to the main University campus, with a busy local street, Wister Street, separating the two.  The existing building would need to be extensively renovated as well to provide for its new function for the nursing program as well as the temporary home of the science program during the two-year renovation of Holroyd Hall.

Existing topography and grades in this area have Wister Street at a lower elevation than the hospital and the campus.  This presented a difficulty since the University’s main walkway, McHale Walk, would need to be extended across Wister Street to access the former hospital building.  This would result in a busy pedestrian crossing of the roadway with less than ideal sight distance and traffic conditions.  It was decided that a pedestrian bridge would be a more effective solution to this problem and would allow direct entrance from the main campus and McHale Walk into the former hospital building.

The pedestrian bridge provides enhanced accessibility between the newly-added West Campus and the remainder of the Main Campus.  The alternative, an at-grade crosswalk with a traffic signal or other control device, would have been less than ideal, as existing topography and grades would have made access to it indirect and lengthy.  This would make it less desirable for users.  The bridge allows pedestrians to cross the street without the interference of traffic, and vehicles are not hindered by students crossing the street. 

Scheduling was a key part of this endeavor since the existing Holroyd Hall could not be closed for expansion and renovations until the hospital building was available to house the programs and classes conducted in Holroyd.  Given the estimated duration of the Holroyd Hall renovation (two years) and its planned start date of May 2008, the bridge would have to be in place once the hospital building was ready for occupancy, since this was the main path that students would use between the building and the remainder of campus.  The project additionally had to be scheduled to allow each component to occur and be completed at key dates, generally dependent on the academic year schedule, to avoid disruption to educational programs and student activities.

Urban Engineers (Urban) was brought into the design team to handle the site survey, environmental compliance, utility assessment and relocation, site grading, stormwater management, and structural design of the proposed bridge.  Ueland Junker McCauley Nicholson (UJMN) Architects was the prime consultant for this endeavor, assisted by Vinokur Pace Engineering Services (VPES), which handled electrical and communication line design and relocation.

The bridge would require the relocation and accommodation of several major underground and overhead utility facilities.  McHale Walk occupies the bed of a former City street which still serves as a utility right-of-way.  Significant Peco Energy and Philadelphia Gas Works (PGW) underground lines and facilities are located in this right-of-way.  The original alignment of the bridge, proposed to cross Wister Street at a 90-degree angle, had to be revised to a slight skew to accommodate underground utilities.  Similarly, the length of the bridge nearly doubled (from 75 feet to 141 feet) because of the skew alignment and the location of the east abutment, which had to clear two underground vaults and two large utility lines.

To minimize the inconvenience to users of Wister Street, Urban specified a prefabricated bridge.  The bridge was shipped to the site in three 45-foot segments and assembled on site immediately prior to being erected.  The erection required a 2-week closure of Wister Street.  Construction of a conventional bridge in this location would have resulted in a street closure for at least three months.  In discussions with the City Department of Streets during design, it was felt that Wister Street could not be closed for such a duration given the limited available and adequate detour routes in the area and the concerns of residents of surrounding areas about diverted traffic on local streets. 

Design was coordinated with the renovation work on the former hospital building.  The building was modified to provide an entrance lobby and outdoor plaza where the bridge would connect directly into it.  Several structural modifications were made on the building to accommodate the bridge.  During design, it was found that provision of a separate column immediately adjacent to the building’s exterior wall would be preferable to the building directly supporting the bridge, so this design revision was made.

Careful coordination was required with the City’s Department of Streets.  In addition to the approval of the street closure noted previously, permits were required for the utility line relocation and the occupancy of the street right-of-way by the proposed structure.  An Ordinance of City Council was needed for this occupancy and this had to be tracked and facilitated with City Council to have it passed during the Council’s legislative season to have in place prior to any construction.

Advance utility work began in April 2008, with the east abutment of the bridge starting in June.  The bridge itself arrived on site in late July and was placed in early September.  The project accomplished the University’s goals to unify the Main Campus with the newly-added former hospital campus on schedule.  The University will continue its expansion and modernization program with minimal environmental and community impact with its planned continuing beneficial use of the former hospital buildings and the several “green” features in the new Science and Technology Center.

Project partners included the design team (UJMN, Urban and VPES), the construction contractor (Seravalli, Inc.), and the bridge fabricator (Contech).