AERODROME SIZES.

New Zealand Herald, Volume LXVI, Issue 20438, 14 December 1929, Page 8 (Supplement)

AERODROME SIZES.

HINTS FROM AIR MINISTRY. This memorandum, issued by tbo Air linistry of Great Britain, should prove f very great valuo to those municipal uthorities who are at present contemlating the selection of a landing ground. Besides giving the various sizes necesary for a ground, the report contains illirmation which will save much trouble nd expense, since, for example, i is very easy to purchase a nice ground a summer only to find that aeroplanes ink up to their axles in mud during he winter months. Location I.—A civil aerodrome must o situated as near as possible to the entro of the town it is required to erve, otherwise a very large proportion f the time saved in travelling by air irjll be lost in travelling between the erodroine and one's final destination. 2. It should bo borne in mind that he chief air routes from a town will irobably radiate in only one or two lain directions. In order, therefore, to void the majority of passengers having 0 cover the.same ground twice, i.e., havng to travel from the town to the aeroIrome and then fly back over the town, he aerodrome should, other conditions >eing equal, be situated on the side of ho town from which the majority of he routes radiate. •3. In considering the matter from the ispect suggested in paragraph (2) above, t should, however, be remembered that, (specially in the case of an industrial ;own, the aerodrome should never be iituated on the side of the town over which the smoke, dust and consequent "og is blown by the prevailing wind. 4. An aerodrome situated near a river >r a largo expanse of water will often suffer from fog. 5. A plateau often makes an excellent lite for an aerodrome, as high ground is anaffected by low-lying fog and is usually ;asy to drain. Too high a plateau should iot, however, be selected, as on days ivhen the clouds are very low pilots might suffer from the handicap of entering the cloud almost immediately after taking off from the ground, while it would ilso be very difficult under such conditions, for an incoming pilot to find the aerodrome. 6. The aerodrome should not be situited at the foot of or even near a hill or very high ground as the latter may cause 1 serious obstruction and thus endanger the aircraft. Size. —1. .The dimensions of an aeroirome which is to bo used by the larger types of aircraft should not be less than 500 yards in all (directions and should, il possible, be 800* to 1000 yards. Only n very exceptional circumstances will a site affording in any direction a clear run of less than 600 yards be licensed, and in that case the absolute minimurr will be 500 yards. Should it be necessary to reserve a site measuring less than 300 yards in any direction, all the ground mtside of and within 100 yards of the perimeter of the aerodrome must contair no obstruction higher than the average sft. fence or hedge. 2. For light or small aeroplanes, a lite measuring 400 yards in all directions vill suffice, subject to conditions regarding i clear perimeter contained in paragraph (1) above. Obstructions. —1. A site should not be :hosen which is surrounded by or even idjacent to insuperable obstruction such is church spires, tall chimneys, etc. Ar■angements can usually be made for the •emoval of trees. 2. An obstruction diminishes the availible space for landing and taking off by i distance equal to ten times its own leight from the foot of the obstruction, "f, for instance, in a certain direction, .he aerodrome measures 700 yards and here is a row of tall trees 60ft. high in the border of the aerodrome, the useul available space will be only 500 yards, hat is, 700 yards minus 200 yards (ten .imes 60ft.), Gradient. —1. The surface should be smooth enough to allow a motor-car to 30 driven over ifc at 20 m.p.h. without

2. Failing some artificial covering the surface should be composed of turf and should bo strong enough to withstand a pressure of 1 ton per sq. ft. 3. If tlie surface will not withstand a pressure of 1 ton per sq. ft. it may bo necessary to drain it, and to build runways composed of clinker tarmac or concrete, such runways being 500 yards long and 100 ft. broad. A rough but pood test for any surface is {o drive a fully laden 3-ton lorry across it slowly. If there is no tendency for the wheel of the lorry to sink into the ground, it may ho taken for granted that under ordinary circumstances neither the wheels nor tail skid of any present-day aeroplane will sink in.