FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1960
1960 - 1070.PDF
94 FLIGHT, 15 July 1960 Recently off the production line at Schiphol is the Dutch royal Friendship, personal transport for Queen Juliana Keeping Friendship Up-to-date FOKKER LOOK AHEAD FOKKER are giving serious consideration to a Friendshipthat is 7ft longer than the present design, weighs 42,0001band would in some versions be powered by Rolls-Royce Dart RDa.lOs. For military use a swing-tail version of the presentFreightship is under discussion. Also projected is another military version with considerably improved field performance. The stretched-fuselage aircraft would be broadly the same asthat being offered to Eastern Air Lines by Fairchild; both factories work in very close harmony on Friendship developments. Thepresent Friendship is not structure-limited and Fokker have realized for some while that for moderate climates a more efficientaircraft would result from an increase in the present Friendship's size and weight. The stretch envisaged would allow another tworows of seats to be installed, to bring the standard total to 48, plus an additional 1-Jft for freight. Broadly speaking, the matchedpowerplant for the Long Friendship (Flight's suggestion for a name) is the Rolls-Royce RDa.7—the engine of the present 200series aircraft—but for hot and high climates performance can be restored by specifying the RDa.10. Eastern's reasons for proposing the RDa.10 powerplant aredifferent; the most powerful Dart would allow them to save an estimated $lm a year by dispensing with water methanol. Thisorder is an important one indeed, not only to Fairchild (see Flight, June 10, I960) but also to Fokker. The Dutch firm will go aheadwith the Long Friendship in any case, but upon the Eastern order will depend how this is done. If an order from Eastern is forth-coming in the very near future, it is to be expected that the airline will ask for the minimum number of structural and installationchanges to complete the stretch. On the other hand, if there are no immediate orders to be filled—but promise of some—Fokker's technical staff hanker after more major design changes that would bring the Friendship thoroughly up to date and allowa number of "state of the an" improvements to be included. Developing structural knowledge might make some retoolingnecessary, and while the airframe as a whole was being recon- sidered, better sound-proofing (by building in anti-resonancedampers) and provision for a dP increase from 4.2 to 5.51b/sq in could be incorporated. The stretched aircraft would have extra length built in bothahead of and behind the wing, but because the tail arm would be increased, no tail changes are likely. On the other hand, the under-carriage would have to be altered, both on the score of additional load and because present Friendships are a shade light on thenosewheel at aft e.g. and sweeping back the wheels would effect an improvement. During a recent Flight visit to Schiphol it was explained thatstretching on a "least-changed" basis might take say, 200,000 engineering man-hours; a full-scale programme could occupythree times as long. What course of action the factory will pursue is, naturally, a major policy decision that will depend uponFokker's other commitments. Fairchild's possible order from Eastern is one of them; Fokker work on the Breguet NATOproject, the Atlantic—for which they are building the centre section—is another. A third might be the so-called "STOL" ver-sion of the F.27, discussed on these pages on June 10, 1960, in relation to Fairchild. Reference to this aircraft (Fokker, whooriginated the idea, call it the F.27S) is made later. Discussion of Friendship improvements leads to questions ofstructural experience with the design after 150,000hr have been flown in service. "The wisdom of hindsight after five years," said There is little evidence here of a slackening in the pace of Friendship production. In the foreground are the fuselages of two Freight ships with large forward cargo door. The aperture is big enough to load a Dutch DAF car, which is about the size of a Mini-Minor I. C. van Meerten, Fokker's chief engineer in charge of the Friend-ship project, "leads us to think that the decisions we took in 1953 were the right ones." He had "no hesitation" in saying that thehigh wing was the correct choice. There was a real aerodynamic advantage, there had been no objections from operators in wintrynorthern latitudes (he cited Wien Alaska) and safety had been proved on the six occasions when, for one reason or another, awheels-up landing had had to be made. Damage had occurred to the fuselage belly, propeller tips and—as ihe aircraft settled—towing tips, but nacelles and fuel tanks had remained untouched. What about the Friendship's structure, particularly the multi-laminated bonded-sheet-metal technique? How did this measure up to the fail-safe knowledge of 1960, seven years or more afterthe Friendship was conceived? "Of course," said Mr van Meerten, "fail-safe knowledge then was not what it is now. We have done alot of work on the structure and it has been made fail-safe with a proven 30,000hr safe life; we used a statically indeterminate struc-ture and the result has been made quite satisfactory. Nevertheless in the light of present knowledge we should look more towardsstatic determination of individual members for fully fail-safe design. We might, for example," he added, "alter the tension sideof the wing structure, and there are some critical detail parts where more fail-safe design could now be applied." About metal bonding Fokker were very happy. Mr van Meertensaid that it was being used on the Breguet Atlantic. But, he said, nowadays greater use would be made on the F.27 (if time could beput back) of chemical milling, which was more refined and might be cheaper, as fewer parts were involved. Fokker had "fullconfidence" in bonding. It was light, could easily be reinforced, and stress-raising rivet holes were practically eliminated. Oncebonding was right (and in the early days of the Friendship it had not been easy to get it right) it stayed right. Independent confirmation of Fokker's belief in metal bondingprimary structures was given by the firm's chief structural engineer. There had, he said, been 36,000 simulated flights on thetest wing/fuselage combination and the fuselage had been put through 125,000 pressure cycles. After a long series of componenttests and crack propagation studies, a non-fatigue-critical airframe had been developed. If the Friendship was started as a newproject now, he said, "we should adopt broadly the same lines as before." Service and overhaul were in some respects not perhapsas easy as they might have been, and for his part he would advocate the adoption of more through-bolted structures. Never-
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
