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Aviation History
1939
1939 - 1237.PDF
together with certain radio indicator dials, should be mounted in a standard manner, that suggested being in two rows thus (reading from left to right): top row— A.S.I., artificial horizon, rate-of-climb indicator, V.H.F. beacon receiver course and glide-path indicator, flap and undercarriage position indicator, A.S.I., artificial horizon, rate-of-climb indicator. Bottom row : Sensitive altimeter, directional gyro., turn-and-bank indicator, radio compass (or visual indicator for D/F receiver), absolute atmos pheric pressure meter, sensitive altimeter, directional gyro, turn-and-bank indicator. The compass position is best chosen for freedom from local magnetic and electrical influence, but should be such that comparison with the directional gyros is easy. If an automatic pilot (desirable in aircraft large enough to warrant it) is fitted, it is best placed centrally. Wireless Demands The radio installation must be regarded as an integral part of the aircraft, and not as a necessary evil to be tucked away in any odd corner that can be found for it. The use of R/T should not be countenanced, as it has no real advantages. It can, in certain circumstances be worked by a solo pilot himself, but because such a pilot has quite enough to do in thick weather without work ing two-way radio, this practice should never be adopted. R/T is, of course, entirely out of the question for inter national flying because of the language difficulty. It is in almost all cases slower and less positive than W/T, and is also technically undesirable in Europe (where there is such a shortage of frequencies) by reason of the fre quency spread associated with a modulated carrier. In addition to the usual two-way W/T equipment, there should be installed : — (a) A simple emergency transmitter with a range of at least 50 miles, so arranged that it is entirely independent of the main transmitter as regards current supply, etc. (b) A medium-wave straight and D/F receiver entirely independent of the main receiver, and fitted with an en closed D/F loop. The D/F readings should be obtained on a verge ring which can be set to the course steered, and the visual indicator (which appears to be the most satisfactory means of showing both '' sense and minimum) must be mounted close to one of the directional gyros to facilitate accurate checking of the course at the instant of taking the bearing. This receiver and the loop gear must be within reach and workable by the pilot, so that he, or the second pilot-navigator, can use it on the various medium-wave naviga- A rough sketch indicating the duplication of blind flying instruments and the simplication of other instruments as advocated by Mr. Brent. The instrument panel is "broken" to indicate the absence of a section which might be devoted to engine instruments and other minor necess ities not strictly coming under the heading of flying instruments * FLIGHT. APRIL 27, 1939 The author advocates convenient placing of the radio operator in relation to the pilots. As yet, unfortunately, ordinary airline equipment does not permit such palatial control quarters as those found in the vast Boeing 314 fly ing boat. Here there are a navi gator, two pilots, radio operator and flight engineer, each with his own conveniently arranged sphere of operations. tion beacons, broadcast stations, and medium-wave approach beacons which are available. It is not generally appreciated that D/F on board the aircraft is only practically possible in bad weather if such a separate re ceiver is fitted in this way, for the radio operator must keep continuous watch on the two- way communication frequency to avoid the possibility of missing vital messages. The D/F loop should be care fully swung in flight taking at least three readings at about every 20 degrees round the scale, and making correction curves for all frequencies used (generally a single curve will serve over a range of about 300 or 400 kcs, but this will vary in individual cases). (c) A V.H.F. approach beacon receiver capable of adjustment to cover the frequencies of all beacons which may be used. With this equipment provision is made for most eventu alities, including transmitter or receiver failure—this being essential when it is considered that an aircraft in fog is helpless without two-way radio communication and is a menace to all other machines in the air within a large radius—and in nearly all cases the whole of the radio navigation can be done without burdening the already overloaded communication frequencies with position-find ing signals. There are always new instruments of one kind and another becoming available—e.g., the new R.C.A. radio- compass and the radio "terrain clearance meter"—but these are not yet available here, and the suggestions made are framed with consideration as to what equipment is actually available for use in this country. The three phases of a flight in foggy weather—of course, there may not be fog over the entire route in all cases— departure, journey and arrival, can be considered separately. The extreme case of the take-off is in what is loosely called zero visibility, but this really means in a visibility of not less than 10 metres or so, for it must be possible to see to move about on the ground. It is essential that the pilot be absolutely familiar with all the characteristics of the intended take-off by having made it many times in clear weather in similar circumstances as regards the aircraft and its loading, the direction, and the position of obstructions. In addition to the routine checking of con trols, motors, fuel system, instruments and radio— assumed to be adequate in any case—a further extra check is needed on the functioning of the directional gyros because of the trust that is placed in them. After setting V.H. E R ecelver Undercarriage &. Rate of ^ Glide-path / Flap Indicator Horizon Indicator /AAJ ^..^ ^^ Climb Sensitive Altimeter Turn&.Bank Radio Absolute SensiiiveVturn IBank Indicator Compass , Atmospheric AltimeterX Indicator (or Visual DIE) Pressure \ Directional Directional Gyro Cxyro
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