Manned Aircraft at CReSIS

The Center has successfully designed, fabricated, installed and deployed custom designed and built antenna faring for a variety of platforms. 

In support of the NASA ICEbridge campaign, University of Kansas and DARCorporation researchers equipped the NASA Dryden DC8 and the NASA Wallops P3 with extensive radar arrays comprising accumulation, snow, KU-band, and the multi-channel coherent radar depth sounder (Mcords) antennas. Again, the use of composite structures is required to tailor the distribution of relative permittivity for radar performance, as well as to ensure structural, aerodynamic and aircraft performance requirements are met.

For the NASA DC-8, the two main fairing design drivers were preventing shockwave formation and minimizing aerodynamic drag loads. Due to the transonic flight regime of the DC-8 much care was given to the external shape of the fairing to prevent shocks from forming, and the resulting shapes lend themselves to composite manufacturing. Structural elements above the radiating antennas are electrically conductive, while those below and parallel to the radiating antennas have low relative permittivity. To the best of our knowledge this is the first radar sounder/imager flown successfully over the polar ice sheets on a turbojet aircraft and from high altitude.

For the NASA P-3B, analyses were completed not only to determine the range reduction of the aircraft and the aerodynamic loads used for structural sizing of the fairing, but also to determine the effects of the presence of the fairing on the stability and control of the aircraft. The size of the wing-mounted fairing was limited due to the need for adequate separation between the fairings, the propellers, and the wing tips. The turbulent flow behind the propeller (prop wash) and from wing tip vortices can increase the drag of the fairing and potentially fatigue the structure due to the series of impinging pressure waves. In this case the lower surface of the wing is used as the reflective ground plane, and so structural elements above, below and parallel to the radiating antennas have low relative permittivity. Thicknesses of composite structures are tailored to the local frequencies of the radiating antenna elements. To the best of our knowledge this is the largest ice radar sounder/imager array flown successfully over the polar ice sheets.

Each of these installations involved high-fidelity, physics-based, interdisciplinary simulations for geometry, aerodynamic loads, aircraft performance, static and dynamic structural response, and radar performance. In each case the design and fabrication of the antennas and the aircraft integration structures were undertaken by the researchers at the University of Kansas with significant involvement of graduate and undergraduate students in Aerospace and Electrical Engineering. To date, these aircraft and these instruments have flown more than 48 science flights, totaling more than 440 hours in Greenland and Antarctica, massing in excess of 150,000 flight nm and enabling collection of over 235TB of unique data for ice bed topography and internal layering. We continue to develop new sensors and platforms, and to operate these platforms to develop unique data sets for the broad scientific community.