FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1950
1950 - 1368.PDF
FLIGHT, 20 July 1950 AMERICAN NOTEBOOK By Stanley H. Evans, F.R.Ae.S., A.F.I.Ae.S. Glenn Martin have a comfortably filled order-book for the 4-0-4, a 40-passenger, pressurized and lengthened version of the 2-0-2, a type which has had a somewhat chequered career. MARTINS' RETURN With wizard fleetness flashing over, under,Bursts from the gloom the Spring's blue-breasted wonder. ("Vision of Spring": F. 1. Douss, 1920.)O NE proverbial swallow '' twittering from the straw- built shed" may not make a summer, but the poet and the ornithologist (and, possibly, an odd aircraft designer or two) might agree that 65 martins go a long way towards it. And when the Martins happen to be Type 4-0-4 winged transports worth some $35 million on the order- book, the count of 65 must produce quite a cheerful twitter in the counting-house of the Glenn L. Martin Co., of Baltimore, Md. Doubtless, in closing the biggest U.S. twin-engined transport deal in three years, some twittering was also felt in the breasts of Martin's competitors in this field—Convair and Douglas. This $35 million deal for the Martin 4-0-4 comprises two airline transactions, 35 aircraft going to Eddie Ricken- baker's Eastern Air Lines and 30 to Howard Hughes' Trans- World Airline (T.W.A.) run by Ralph Damon. The new model 4-0-4 is a 40-passenger pressurized and lengthened development of the existing 2-0-2 model on which the Martin treasury has taken a very severe financial beating, only 31 being sold, of which 24 are in operation by North- west Airlines. Due to inadequate prototype development, the 2-0-2 ran into a patch of bad luck, suffering a fatal wing structural failure in flight, with subsequent grounding for extensive and expensive alterations. However, these 2-0-2 losses have now been written off and the company are back in the black after a couple of very bad years in the red. In 1947-48, for example, the net losses totalled nearly $36 million, whereas last year's operations turned in a net income of $5.1 million. Inasmuch as actual deliveries of the new model 4-0-4 will not begin until the spring of next year, T.W.A. in the meantime have made arrangements with Martin for the lease of 12 of the current 2-0-2 design, with delivery start- ing any moment now-. As these 2-0-2S are delivered, they will supplant the slower pre-war Boeing Stratoliners in T.W.A.'s fleet. What will be the final nesting place of the 2-0-2S on expiry of the lease is problematical at this time, but since, presumably, the parts were already fabri- cated and the tooling was available, no doubt both parties to the deal were able to consummate a mutually satisfactory bargain. Apart from pressurization—with cabin air conditioning designed for sea-level pressure at a cruising altitude of 12,oooft—the main engineering changes to be introduced into the 4-0-4 model will be an increase of gross weight to 43,000 lb and a 39-inch-longer fuselage to accommodate the extra row of four seats. (The 36-passenger 2-0-2 mode] is certificated for a gross weight of 39,900-40,600 lb, the higher figure being permissible with a wet-boosted take- off.) Power plant of the 4-0-4 will be two of the latest type Pratt and Whitney R-2800-CB16 18-cylinder twin- row radials, each normally rated at 2,100 h.p. and deliver- ing 2,400 h.p. with water injection for take-off. Airscrews will be Hamilton-Standard auto-feathering, reverse-pitch, paddle-shaped three-bladers of 13ft lin diameter. Martin publicity pundits predict a top speed of 312 m.p.h. at 14,000ft for the 4-0-4. Seeing that the maximum speed of the 2-0-2, apparently with the same power output, is officially quoted as 311 m.p.h. at 14,000ft and 35,000 1b gross weight, the engineering analyst will no doubt be intrigued with this result—bearing in mind the higher gross' weight of the 4-0-4 and the increase in wetted surface-area of its longer fuselage. A near-300 m.p.h. cruising speed has also been somewhat loosely reported in the U.S. avia- tion papers. Our own slide-ruling on the 4-0-4, based on a gross weight of 38,000 lb and a similar power output to that currently specified for the power plant of the 2-0-2 (namely, 1,690 b.h.p./engine at 14,000ft and 1,400 b.h.p./ engine at 12,000ft), turns up a performance of 308 m.p.h. (maximum) at 14,000ft and 283 m.p.h. (cruising) at 12,oooft. (The corresponding minimum parasite drag co- efficient is estimated at 0.021.) Since, however, no drag penalty has been charged against the longer fuselage, a more prudent estimate would bring down these figures to 305 and 280 m.p.h. A pretty fair idea of the climb performance can also be assessed from the current 2-0-2 specification. With the wet- boosted take-off power of 2,400 b.h.p./engine and a per- missible gross weight of 40,600 1b, the 2-0-2 takes off over a 50ft obstacle in 1,565ft and has an initial climbing rate of 2,200ft/min. If the take-off gross weight of the 4-0-4 is certified at 43,000 1b, the corresponding take-off gross run is increased to 1,750ft and the initial climb reduced to 2,000ft/min, based, of course, on the same power output as the 2-0-2. The 33,000ft full-power service ceiling of the 2-0-2 will drop off to approximately 30,000ft for the 4-0-4. With a capacity payload of 36 passengers and baggage, plus 1,000 1b of cargo, the normal operating range of the 2-0-2, exclusive of reserve fuel for 200 miles plus 45 minutes, is officially quoted by Martin as 830 miles, while the maxi- mum range with capacity fuel of 1,010 U.S. gallons and no reserves is given as 2,020 miles. The corresponding ranges for the 4-0-4, carrying 40 passengers, baggage and 1,000 lb of cargo, are estimated at 750 and 1,890 miles. The certified stalling speed of the 2-0-2 is quoted as 76 m.p.h. at a landing weight of 38,000 lb, which is tanta- mount to a claim of practically 3.0 for the flap-down maxi- mum lift coefficient. This is an unusually high value for partial-span flaps, but in view of the improved type of double-slotted flap design employed and the long span o-f these flaps extending over some 70 per cent of the wing span, it appears perfectly feasible. On this basis, then, the 4-0-4 may be expected to stall at around 79 m.p.h. at a landing weight of 41,000 lb, while the landing distance over a 50ft obstacle is estimated at r,850ft, as against 1,720ft for the lighter 2-0-2. Design for maintenance and serviceability start on the drawing-board and a detailed study of the Martin transport shows how well this aspect has been " designed-in " to cut down the ground time to a minimum. These virtues are much too numerous to detail in these notes, so a tvpical example seen in the structural treatment of the fuselage
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
