FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1958
1958 - 0187.PDF
197 This sketch is based upon published American descriptions of the X-15. 1, pitch and yaw control jets; 2, advanced instrument display including pictorial information from inertial navigation system; 3, pressure-suited pilot in cockpit with glass windscreen and side portholes; 4, integral tankage, probably for ammonia fuel; 5, internal baffles; 6, 12in-diameter pipe conduit, probably acting as keel member; 7, aerodynamic ailerons with rounded corners; 8, integral tank, probably for liquid oxygen; 9, tank for turbopump gas-genera- tor (probably containing H.T.P. and also feeding the control jets); 10, rudder motor; 11, aerodynamic rudder with 12in-wide trailing edge; 12, jettisonable lower fin; 13, anhedral tailplane; 14, retractable landing skid; 15, blunt trail- ing-edge; 16, H.T.P. catalyst pack (wing thickness about 0.5in); 17, roll control jet nozzle; 18, beryllium-skin over lateral conduit fairing; 19, aileron motor. ings. These were developed with a compressed-air test rig illus-trated in our January 24 article, and are now being evaluated in flight, at Mach numbers up to slightly more than 2, in one ofthe Bell X-1B aircraft flying from Edwards A.F.B. Each of the control jets in the X-15 will be a fixed rocket chamber with a1.5in nozzle fed with H.T.P. decomposed "cold." Instead of the usual control column, the aircraft wUl have small levers on eitherside of the cockpit at the extremities of axial rests for the pilot's arms. Either directly or through an autopilot system these leverswill move the aerodynamic surfaces and switch the H.T.P. control jets on and off. Obviously a great deal of research will be necessarybefore the X-15 control system can be considered safe and developed; it has yet to be determined whether, for example, theroll jets on the wings will be precise enough to be operated indi- vidually or whether both will have to be fired with slightly differen-tial feed. The whole system is reminiscent of the air-bleed jets used in the Rolls-Royce and Soviet "flying bedsteads." Reaction Motors have evolved a singularly neat and lightweightrocket motor for the X-15 with turbopump feed to a single chamber with—so far as one can tell—a fixed thrust line. It is notable thatconventional hydrocarbon fuels have been eschewed in favour of anhydrous ammonia. With liquid oxygen this gives a specificimpulse of about 270 and the modest theoretical combustion temperature of 4,940 deg F. It is possibly the latter figure whichhas dictated the employment of ammonia, since the period of sustained firing (up to six minutes at varying thrust) is exceedinglysevere. The propellants occupy more than half the overall length of the aircraft, the entire body from cockpit to fin forming integraltankage for the two liquids. According to Aviation Week each tank contains baffles "shaped like radar dishes facing forward" to con-trol surging and sloshing and to maintain the aircraft e.g.; how the latter can be achieved by a baffle is not stated. The fairings down each side of the body are essential to takethe numerous pipes and services past the integral tankage. In addition, they help to minimize interference between the wingand body, which can become disastrous at Mach numbers greater than 2. Thermal conditions around these bulges are particularlyrigorous and the skinning is reported to be of beryllium through- out their length. In passing, it is worth noting that an Italianreport has stated that the X-15, together with other American vehicles, will incorporate a certain amount of double skinningwith the intervening 0.5in layer filled with lithium—presumably after the manner of sodium-cooled exhaust valves. It is known 16 that the airframe incorporates a substantial amount of brazedhoneycomb, and North American Aviation have, in fact, recently organized a new department to handle such material. As noted in our January 24 article, the X-15 will be air-launchedat about 40,000ft by a B-52 mother-aircraft. Pilots assigned to the aircraft are Joseph A. Walker of the N.A.C.A. and Captain Iven C.Kincheloe, and the latter will probably be the first to explore the aircraft's performance boundaries. Initial test flying will behandled by North American Aviation's own research pilot, Scott Crossfield, who obtained much experience when he was with theN.A.C.A., being the first man to fly at Mach 2. Crossfield will prove the structural integrity and general reliability of the aircraft,but will probably not exceed about 60,000ft altitude and a Mach number between 2 and 3. Primary responsibility for the productive flying of the X-15swill rest with N.A.C.A. The B-52 will be based at either Edwards A.F.B., Cal., or at Wendover A.F.B., Utah, 485 nautical miles tothe east. The aircraft will be released over the Utah base and will conduct its trials along trajectories between the two points, over aroute which is now being very extensively instrumented and provided with facilities for tracking, recovery and data reduction.Primary navigation will be conducted by a pure-inertial system giving the pilot an accurate three-dimensional transient positionin space throughout the flight. Already the groundwork for the programme is being laid, with regular X-1B and X-1E flights fromEdwards and a great deal of special environmental and physio- logical testing. For at least several months it is unlikely that the X-15 willexceed an altitude of between 50 and 100 miles, but the basic vehicle is potentially capable of being taken by a rocket boostunit to a launching height of perhaps 20 miles (the defunct SM-64 Navaho booster should do admirably), and with such a flying startit is hoped that the X-15 can be established in an orbit. Apart from the considerable psychological strain placed upon the pilot,the chief "human factors" problem of orbital flying is likely to be that of providing sufficient refrigeration capacity. It is also diffi-cult to say how the endurance of the oxygen breathing system can be made adequate unless the main liquid-oxygen tank can betapped. Re-entry poses great technical problems, and the pilot's accurate flying and maintenance of correct re-entry angle willprobably be vital. It has been suggested that the first orbital flight may include a number of unpowered "skips" into the atmosphereand out again, although such a procedure would progressively raise the mean airframe temperature. For the final landing, small skids will be extended from the rearend of the fuselage to preserve stability after touch-down. The latter would probably occur at over 200 m.p.h., the lower fin beingpreviously jettisoned. The landing run will take place on the flat bed of the lake at Edwards, using a braking parachute to reduceairframe damage and friction heating. The pilot will doubtless be relieved to get his feet on the ground once more. THE BRANCKER LECTURE THE author of the fifteenth Brancker Memorial Lecture,arranged by the Institute of Transport for last Monday, was A. Cdre. W. E. G. Mann, C.B., C.B.E., D.F.C., Director-Generalof Navigational Services, Ministry of Transport and Civil Aviation. His subject was The Control of Air Traffic. The main body of the paper was devoted to an expert summaryof the history and present-day position of traffic control; in die final section, A. Cdre Mann looked at future problems. Thoughhe was careful to avoid committing the Ministry, he commented on the big problems ahead in a manner indicative of the directionsin which Ministry policy may lead the air traffic of the future. It is hoped to deal with the paper more fully later: in the meantime,selected points are summarized below. (1) Having outlined a typical jet transport flight-plan, A. Cdre.Mann said: "Today no such flight plan could be given a safe clearance by Control and I doubt if it will ever be possible to doso. I trust that the operators of jet aircraft have taken account of this." (2) Four long-range radar stations could cover the U.K.'scontrolled airspace from a height of 5,000ft to at least 30,000ft. Secondary radar with transponders in aircraft would further increase coverage, particularly in height. (3) "The United King-dom . . . has consistently advocated for many years the inter- national adoption of the British Decca Navigator System in high-traffic-density areas. This would be a solution to the need for increasing traffic control capacity, since aircraft would be navigatedmuch more accurately." (4) "The United Kingdom has encour- aged the development and adoption by airline operators of aBritish self-contained airborne device giving high accuracy, known as Doppler, and has also undertaken the testing and evaluation ofthe ground-based long-range system known as Dectra." (5) "Even when electronically collated and stored, it is difficult to see howthe information [which should be automatically transmitted from the air to record progress of every flight] can be presented toexecutive Control Officers in a three-dimensional form that will clearly indicate the present traffic situation and that about todevelop." (6) "Is there not a happy mean between an approach speed of zero knots [VTOL] and one of 160 knots [big jets]? Ifaircraft could approach at a common speed of the order of 80 to 100 knots, higher landing rates and increased airport capacitiescould safely be achieved."
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
