Status 

The actu ator mech anical u nits for the flight test v ehicle have been  fabricate d and installe d (Figure 14).  Some fun ctional testin g wa s succe ssfully compl eted with the u nit installe d in th e vehicl e bef ore th e proje ct  was termi nated. A flight-desi gn a ctuator qualifi cation unit was su ccessfully  tested by t he drive unit  contracto r, Moog, in a loa ded test stand that simula ted the full ae rodyna mic lo ad. Initial co mpone nt leve l  testing of th e seal sho wed promising succe ss, but later te sting i ndicated some seal a brasion problems  that remain to  be resolved.  

The thermal seal  system and actu ator thermal  protection syste m reached only comp onent level prototype  fabrication be fore the p roject was termi nated. Detaile d desi gn of th e thermal p rotection shell for the lo wer  arc a nd of the se al mou nt to fuselag e skin interfa ce were n ot compl eted. T he flight unit flaps we re  installe d on the vehicle, but wit hout using the flight desi gn fasten ers. Th e vehicle lo wer skin wa s  temporarily removed fo r integratio n of the flaps a nd actuators, but wa s nev er reinst alled , which wo uld  requi re temp orary remova l of the fla ps and actuators. T he flight  unit controlle rs were used fo r testing, but  with tempo rary mounts and  wire routing s.     Conclu sion 

Despite th e prematu re termination  of th e X-3 8 V-201 proje ct, the fl ap actuato r developme nt team l earned   a numbe r of valuabl e lesso ns. 

Concerns regarding the feas ibility of constructing and in stalling the arc with suffi cient accuracy to permit   smooth o peration of the actuato r beset the team from the be ginning of the rede sign, yet it ultimately  function ed pe rfectly. Ho wever, with little experien ce to serve as a  guide, all of the part s were desi gned  and fabri cated to the tightest po ssible tolera nces a nd weeks of effort were spent to align the flaps a nd  actuato rs as close to the theoretical lo cations a s possible (i ncluding offsets for known errors). Also, many   element s of t he system were devised t o reduce free play b etwee n the components a s much as possible   since it wa s unkno wn ho w mu ch woul d be a ccepta ble. Such ext reme effo rts adde d substantial expen se  and in the future it woul d be instru ctive to explore the toleran ce for errors of this actuato r configuratio n. In  particula r, the fabri cation of the large I nconel p arts became fa r more difficult  than a nticipated an d onl y  succeed ed af ter multiple fa iled attempts,  the det ails of  which exce ed the scope o f this paper. 

Altogether, creating the a ctuator system utilized at least five di fferent com puter aide d desig n (CA D)  systems. Three separate systems were used for th e design: on e each by the flap sup plier, the drive u nit  supplier, an d the vehicle in tegration tea m. The int egration team al one al so use d two other systems, one   for stress a nalysis and o ne for the rmal analysi s. Kee ping all of th e different m odels syn chronized was a  signifi cant p roblem th at was seriously comp ounded by the g reat difficultie s of tran slating  betwee n the   different pa rametric, solid model CA D systems. T he difficulties of transl ating be tween h uman langua ges,  different syst ems of mea surem ent, and  coordinatin g across world wide di stances were trivial comp ared to  the pro blems and the va st amount s of lo st time tran slating bet ween the CA D system s. In retrosp ect, mo re  effort sh ould have be en m ade to stand ardize on a single system as the practical state of th e art in CAD  transl ation le aves mu ch to  be desi red. 

Somewhat o utside  the scope of this discussio n of the a ctuato r, but wo rth noting, was the difficulty of  installin g and  alignin g the flap syste m. The hin ge design had fa r too many d egrees of fre edom betwee n  all of the pa rts and required an i nordi nate amou nt of time to integrate on th e vehicl e. Fu ture p rojects  would do well to re duce the num ber of deg rees of freedo m during i nstallation a nd design into  the  hardware too ling that allows for o ptimal mech anical positionin g adju stment. Elements a s delicate and   expen sive as hot cont rol surfa ces should not b e left to ha nd-clam ping system s for mecha nical  adjustments and installatio ns. 

Although in complete, pro gress to date  on the seal system  has identified a d earth of suita ble techn ology  for flexible, hi gh temp eratu re and oxidati on resistant  material s that are sufficie ntly robu st to form el ement s  of a m echani cal syste m intended  to o perate i n the hypersoni c environme nt. Several i ntriguing concepts  389