ORDLB-RP (9 Nove mbe r 1967) SUBJECT: UFO Observation, 9 Octobe r 1967 U . S . Army Engineer Division, Ohio River; Ohi o Rive r Division La =~tories, Cincinnati, Ohio 17 J anuary 1968 TO: Headquarters Foreign Technology Divisio n (nFSC), Attn: TDET/UFO, Wright-Patterson Air Force Base, Ohio 45433 1 . In the basic letter, four questions we r e aske d con- cerning the flying obj ect (UFO} report and the inclosed photo- gra~hs and soil sample s . The following information wa s devel o ped i n r9ply to the four questions and ma y be l1elpul in your eval- 2 . With referen c e to the first question concerning a feasible explanation for the caus e of the impressions in the s a:-.:, the following paragraphs d escribe the limite d l aborator y study which provided r elevant information. Site Information a . These Laboratories have on file numerous Corps o f Engineer Conditio n Survey or Airfield Pavement Evaluation r e po::ts of Davis- Honthan Air Force Base. Although the infor- matio~ in these reports primarily relates to the airfield, general observations of soil and climatic conditions ap}?ly to t~e ~ocation of the UFO observance. b . The cli mate in the area is generally arid. in the f all m~nths average s about 0 .75 inches per ?ree grou~d 'va~er is rarely found at depths less than c . Tnc ~a~ural subgrade soils in the area consist main:...!' :.:: sa.:1d (SC-S~l) , gravel (GP) , and sandy clay (CL) in var~o .... ..:. ,?::-cportions with an appreciable filling of lime c arbonate . Sand'i clays occur in many areas to depths of at least six feet, and c~:iche materials, ranging from a loose to medium d ense str e.are of common occurrence at depths varying from three ORDLB-RP (9 November 1967) 17 January 1968 SUBJECT: UFO Observation, 9 October 1967 d . The strength of these dry soils is low in their nat'"..l.:al uncompactcd s tate. The modulus of subgrade reaction is 0:1 the order of 100 psi per inch. This measure of soil stre~gth is significant because of the way in which test values ar: obtained. The test procedure involves applying a static load to a 30-inch diameter plate and observing the indentation bel:>w the ground surface. Air Force Photographs e . For convenience in discussion, the Air Force photographs have been assigned the arbitrary numbers Al through f . Photographs Al through A3 show many footprints in cating sandy material that is both dry and loose. The footprints near the impressions indicate a sinkage of about 1/2 inch which implies a material that could be easily dis- turbed by shovelling. Static loading on a circular footing of approximately 24-inch diameter would induce a heaving failure including a raised lip outside the footing. Hm-1ever, the cross section of the lip would show a rounded rather than a sharply peaked shape. Photographs A3 through A6 indicate areas immed- iat~ly adjacent to the depressions that appear smooth. The overall appearance suggests a flattening of the loose surface ma~erial bv a fla~ board or the back of a shovel. h . The shape o f the raised lip (Photographs A2, A3, 3.::~ ~-6) is sl:a:-_?ly peaked. This sharp lip is not char- ac~-:~:~:c of soil =ailure due either to static surface loads or :~ ;~2~ta fro~ high-velocity impact. Photographs A2 through ~6 reveal disturbances on the inside of the depressions which further rule out static loadi-:::;. These disturbances are aligned along a diameter of (9 November 1967) lst Ind 17 January 1968 SUBJECT: UFO Observation, 9 October 19G7 ea=~ depression and consist of a -ridge of material built up o~ = inside surface of each depression. The ridge is not u =~rm in height but is divided and curved as shown by Photo- s;:::::t_:--.:-ts A3 through A6. The inside sur face of the depression ct:--::r than the ridge appears smooth but less compacted than th.: ground surface of the immediate vicinity. Sir .... lation Tests j . In an effort to simulate the observed depressions, th2se Laboratories conducted a limited series of tests based on e hypothesis that some mechanism other than static or dy- na c loading produced the unique appearance. standard sieve analysis completed on the ma- terial sent to us from the site revealed a sandy material similar ~n q=adation to bank run sands present in the Cincinnati area. -~ g.: ~vel pit near t:i1e Laboratories has sand of similar gradation co the Arizona sand and was selected as a site for field testing. 1 . The ridges in the left-hand depression of Photo- gra:;?~"1 A6 appear to be the result of a rotational digging ac t:i.on. To t est this hypot"hesis, simulation tests in the laboratory and in t:--:e field were co:<1pleted and recorded on Photographs 01 through 07. Photographs Ol through 03 were taken in the laboratory using d::y s ?-'1d. The re:::ai!::..ng photographs were taken at the nearby g!"ave:. :9it. m. The device used to make depressions in the labor- at:.:.-: -.,,~.s a steel p:::.a'.:.e measuring 6" x 7" x 1/2". Photographs Ol :.: .:: G '1 shO\v t:-.e _?a"':tern developed after standing the plate o~ ~::E = fo::ci~; i t , corner foremost, into the sand and tu=~---:~ counte~c~oc~vise. The sand was level and smooth at ~:-: 2 :.a=t of each test . The raised lip with its sharp crest was cz.\.:5e d by spillage around the leading edges of the plate and no~ by displacement. The ridge was formed by simply stopping ORDLB-RP (9 Novembe r 1967) 1st Ind 17 J anuary 196 8 SUBJECT : UFO Observation, 9 Octoher 1967 the rv~a":.ion and removing the plate vertically. However, the resul~ant ridge appeared too large in compurison with the A::izor:a disturbances. Photograph 03 shows that .the volume of the r_dge can be reduced whil e s till retaining the sharp peuked toro al lip. This depression was started in the same way as the ? vious tests except that several h~ndfuls were scooped fro:n :he bottom of the depression after which the steel plate was a :iain rotated. The 7 -inch edge of the plate was parallel to th: ground surface during the rotation which was completed after ~he scooping operation. n . Photographs 04 through 07 record the tests com- pletej in the field. The large piece of pl~1ood shown on Photo- graph OS produced all depressions in this test series. The principle difficulty with these tests was the existing natural '"ater content of the sand. The material did not flow as readily as th: dry sand tested in the laboratory and left marked striations alo:1g the sides of the depression. We were unable to obtain photo- graphs of the freshly made depressions because of malfunctioning equip~ent. Photographs 04, 06, and 07 were, howeve r , made a ~eek after testing and indicate a softening of the material due to \ve~thering. Photographs A4, AS and A6 shmv some breakdown in structure a long the lip presenting the possibility of the star":. of weathering. Photograph AS was made during the second visit. ":.o the gravel pit and shows the effect of moisture on the cor.fi ation of a freshly-dug depression. All of these de- press~o~s approxima~ed the dimensions of the Arizona disturbances. The ~o oms of the ceo~essions in each case contained loose rna- ? . T.~e s pe and depth of the depressions rul e out the ?~53- lity of e~tner static or dynamic loading applied throug~ 2~-inch diamet e r footings. p . The general appearance of the depressions can be dup~i~a~ed by rotating a vertically oriented, f lat plate in loo3:: s and. ORDLB-RP (9 November 1967) 1st Ind 17 January 1968 Su3JZCT: UFO Observation, 9 October 1967 3 . With reference to the second question concerning 7 weight necessary to make an impression of the size re- ~c ed, the strength of dry soils can be base d on a static lcz.:l test on a flat plate. The estimated modulus of subgrade r::a>. ::tion for the general area is about 100 psi per inch. If a o-foot diameter plate is loaded statically on such a material, af:roximately 500 psi would be required to produce the observed pe-.::tration of 4 inches bel ow the ground sur ace. The loading i nsity and penetration depth corresponds to a tota l static lo.:d of about 230,000 pounds. Assuming that each pad or vehicle su~port carried thg same load, the total weight of the object \lo-_:.d be about 460,000 pounds. If the observed object \vas solid ste~l, t h e required vehicle size (volume) would be still over ni~e times larger than the 4-foot diameter by 8 -foot high object described. The estim~ted modulus of subgrade reaction of about 100 psi per inch used above was the minimum found for the area in -::~e site data. The soil sample furnished and assuming a low moisture content for the soil, based on the photographs, would incicate that the ~odulus of subgrade reaction would be in the range of 300 psi per inch. The higher the actu a l modulus, the grea~er the weight woul d have to be to produce the observed pcne- tra on. On site t ests coul d provide a more accurate value , if nec:ssary, for the nodulus. 5 . As desc=i~ed in paragraph 2m and 2n, the depressions t:-:;.-:: e produced l:: the laboratory and in the field were made :::.:: ~ :;~:--::;le indiv:.:l.;al whose height and weight are 5 p:J..:~ . .:~. This pe=s~n required moderate effort to turn and embed ~. ~7i th re:fe=ence to the third question of ~.-Jhether it woul:: ::: :feasible for a two-legge d object of the shape described to :;.a :e the depressions, the object sketched would be inherently unst~::::.2 unless it contained some sort of stabilizing mechanism or t'-..e ~.,o legs penetrated deeply into the soil. ORDLB-RP (9 November 1967) lst Ind 17 January 1968 UFO Observation, 9 October 1967 7 . With reference to the fourth question of whether it uld be possible for a vehicle to make a deep depression anc leave a lip like those in the photographs, the results of :.ne laboratory study provide some insight into ways the dep~ession can be duplicated. Dased on required weight and sta~ility, it does not seem reasonable that a vehicle would produce the depressions. Such depressions , hov-1ever, were re- pro ced with little difficulty by a single individual. IU! Pt..Y TO DEPARTMENT OF THE AIR FORCE HEADQUARTERS FOREIGN TECHNOLOGY OIVISION <AFSC) WRIGHT. PATTERSON A I R F O RCE BAS E . OHIO 4!!433 ~ -. ')'oservo:tion, 9 October 1967 .:::: ..) Ri.ver Division Ln.borutory 5:51 t!.ar:i.emont Avenue ~.n.rier:tont, Ohio 45227 1. The Aerial Phenomena Branch is in receipt of an unidentified :-: .. .:.ng object (UFO) report that occurred on 9 October 1967 at Tucson, k -::.zona; a copy of tbi.; report is attached. ::>. From the inclosed photographs and soil samples, wonld it o~ possiole to give us a statement as to what could have po3sibly cr.,.:. sed the impressions i n the s anJ? b . Could you give us inforrn:..ttion on the \Ieight that Hould be necessary to make an i~.prcssion this size? c . Hould it be feasible for ?. t\IO-J.eggcd object to make thi::> type of ir:1presslon? d . Would it ha~e b~en possible for a vehicl e to make a deep de?-::ession and leave a lip lik~ those :ln the pictures? 2 . Your assistance :b providing any information on this case will be hel ul in our eval tion and i s appreciated. Please return the a::~::-::hed ca.se and yo:.tr reply to the foll O'-ling address: ?':'D ( TDET /UFO) ;.~rial Phenomena Br a nch J,FB, Ohio 454 33 ace File, 9 Oct 67, Tucson , J\riz.onu On 12 !"ebr.Jary 1963 ,_.e forw1ird~d tbe copy of our cese file o n the tJ?O l a noing of 9 Octobe r 1967, Tucson, Ariz . we inadvertently forwarded you our only copy of an in- ':Ot!ling ~essage from Davis-tl.onthan AF'B,., Ariz. The :nessuge .. as unclassifieC:!, cite 18023, 11 Oct 67. \.Je would tp,9reciate your returning the original messa~e. If you -..tsn to !ilake a copy of it there, go ahead , o~hen;ise, ~ ~.,1.11 meke a Xerox here and send 1 t to you. ~a you for your assistance in ~trieving our lost :.:te s sage ':.l-P AFB, Ohio 4 5!.o2G - UNIVtRSITY 0 f COLOH~1DO SUBJECi u !="0 LANDING OF 9 OCT. 67, TUCSON, ARIZ RE: YOUR MEMO OF FEBRUARY 17, 1968. ENCLOSED PLEASE FIND THE ORIGINAL MESSAGE.