Project Blue Book Mariana UFO Incident PDF

Read from the scan by GLM-OCR; expect the odd misread word.

42° off in the vertical direction from the optimal reflective angle. * (This means the flight path would have to be headed 26° more west and the plane rolled 21° for optimal reflection to be achieved.) An assumption implicit in this argument is that the objects were at optimal angle of reflection just as the first frame was taken. The optimum angle didn't occur later as no maximum of intensity is observed (just an approximate monotonic decrease in intensity, cf. figure 6). That the objects were first photographed just at their optimal reflective angle would be fortuitous indeed. Thus 52° represents the smallest angular discrepancy and in all likelihood this discrepancy in the horizontal was greater. The last two facts assume particular importance when it is noted that a typical airplane will reflect only when it is within 10° horizontally and 20° (dim reflection up to 45°) vertically of its optimal angle of reflection †. In fact, assuming that the objects kept a nearly rectilinear course, their brightest sun reflection should have occurred some 30° after they disappeared from view. Fourth, the distance of these hypothetical planes would probably have been over five miles; otherwise on this very clear day (visibility 60 miles) they could have been rather easily identified as planes on the film (at least on the last few frames where the bright flare was very small, cf. figure 10(c)) or by Mr. or his secretary **. This distance, however, seems much too large when one considers the size and intensity of the images on the first few frames. Admittedly these images don't actually portray the real dimension of the reflecting surface (cf. appendix II) but they do give an indication of the relative magnitude of the size. This indication would roughly put the reflecting airplanes between one and three miles from the observer. The fifth consideration which strains the airplane hypothesis is the reported hovering of the UFO's. This might be accounted for by a flight path at a very great distance from the observer or one making a very small angle to the observer so that the traverse component of velocity would be small. The latter possibility is ruled out because of the sun's position relative to the plane and the former would necessitate an extreme decrease in the plane's distance in a very short period of time.

* Optimal reflection is achieved when the angle of incidence of the sun's rays on the object is equal to the angle of reflection to the observer, the angles being taken with respect to the axis of the aircraft.

These facts are confirmed with respect to the F94 Jet and DC-6 airplane configurations. The discrepancy in the sun's angle of incidence vertically excludes reflection from vertical planer surfaces such as tail fins, etc. but still allows some partial reflection from the curved fuselage of the plane. These reflections are less intense and in the vertical plane may be observed up to about $ 4 5^{\circ} $ from the optimal angle of reflection. On the other hand, reflections from the fuselage appear to completely disappear when the angle is off only $ 1 0^{\circ} $ in the horizontal plane, cf. appendix II.

At five miles a typical fifty foot airplane subtends angles of 7' by 2'. The resolving power of the eye is from 1' to 3' (12) while that of the camera set at f/22 is about 1 1/2' (its theoretical resolving power, exclusive of aberrations, is on the order of 40" ), cf. figure 10(b) for the size of an airplane silhouette as it would appear on the scale of the film. These conclusions are borne out by the aircraft recognition silhouette card furnished by the Air Force to the Ground Observer Corps.