FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1956
1956 - 1824.PDF
FLIGHT TEST OF FRIENDSHIP (Left and right) The Rolls- Royce Dart Mk 511 and the electrically de-iced Roto/ 12ft propellers. The nacelle cross- section is oval, with the gener- ators and other accessories grouped well aft at the wing leading edge and corered by a single hinged panel (just visible on the right). not to mention water/methanol tanks, cabin luggage racks and agood deal of air ducting—all these are of plastic. Such lightly- stressed parts can be made simply and lightly in glass plastic,allowing a much-improved skin contour and greatly increased ease of manufacture, particularly where complex compound curvaturesexist. In the control of the Darts a single power lever is used forboth engine power and propeller pitch. In all routine work away from the circuit the indication of power delivery is taken from ther.p.m. gauge. Because of operating requirements the engine is set to run at a minimum speed of about 10,000 r.p.m. in flight.If engine power is reduced below that normally used at this speed, propeller pitch will automatically fine-off in an attempt to maintainthe minimum r.p.m. In this process there comes a time when the propeller will fine-off completely and give tremendous discingdrag, which would prove fatal if it occurred in the air. A mechanical fine-pitch stop is therefore set at 21 deg. Once thepropeller can no longer hold the 10,000 r.p.m. at 21 deg pitch it acts virtually as a fixed-pitch unit giving a certain amount of wind-milling drag. For starting purposes, however, and for various conditions on the ground, the propeller must be allowed to fine-off completely to zero deg. Micro-switches are therefore fitted on the main undercarriage units to withdraw the flight idling stopand allow pitch to go to zero deg when the weight of the aircraft rests firmly on the mainwheels. The engines are started at zero deg and, when power is appliedon the ground, engine speed very soon increases to the 10,000 r.p.m. mark. Taxying is usually done at this r.p.m. During anapproach and landing, when the propellers are against the flight- idling stop, r.p.m. is obviously no longer an indication of powerdelivery and reference is made to the torquemeters, which are mounted immediately below the r.p.m. gauges. As soon as theaircraft touches down the propellers can come back to the zero- degree ground fine-pitch position and there is a noticeable increasein r.p.m. a few seconds after touch-down. A good deal of discing drag is then available to reduce the landing run. The torque-meters, of course, continue to give an indication of power delivery in all flight conditions but, under cruising conditions, they aremostly disregarded. When I flew with Mr. Burgerhout and Mr. Moll I was unfor-tunately not able to make any take-offs or landings because, with the low cloud-base and poor visibility then obtaining, two Friend-ship-qualified pilots were necessary to cope with the traffic control and radio procedures in force at Schiphol. I therefore stoodbehind the flight engineer as he sat in the jump seat, which unfolds from the floor in the flight-deck doorway. We had no sooner taken our places than the starboard enginebegan its characteristic starting-up whine. Immediately after- wards the port engine was started. Very short checks, mainlylisting items in the electrical system, were carried out. The ground generator trolley was waved away and we began to taxi. Mr.Burgerhout used nosewheel steering and braking, with the engines at a little over 10,000 r.p.m. The ride was comfortable and visibility trom the cockpit excellent; we consequently naa notrouble in negotiating some gateways and taxi-way marker boards which were scattered in some profusion over the first part of ourroute to the runway. The take-off run, at full load, lasted about 15 sec and wasfollowed by very quick wheel retraction and a good steep climb straight into cloud. At this point I sat in a seat next to theautomatic recorder installation, and right in the line of the engines. I had two main impressions; firstly, that the quality of the noisewas remarkably similar to that in a Viscount passenger cabin during take-off; and secondly (and as stated earlier), that despitethis first prototype's lack of proper soundproofing, furnishing and pressurization, the noise-level was not at all excessive. We were soon clear of broken cloud tops and climbing in brightsunshine when Mr. Burgerhout handed over control to me. Initially I had a little difficulty in bringing the seat forward againafter getting into it, since the catch simply unlocks the seat on its rails; and, during the climb, it kept sliding firmly to the fullyback position each time I unlocked it to slide forwards. I could have saved myself a lot of jerking and leaping if I had simplyused the obvious hand-hold on the anti-glare shield to pull myself further forward. We were climbing at 120 kt and making goodabout l,400ft/min rate of climb at 13,600 r.p.m. I climbed to about 6,000ft and levelled off, leaving a high powersetting to take us comfortably to 205 kt I.A.S. Both A.S.I.s were of the sensitive type with hundreds of knots shown in a veederwindow and units and tens indicated by a single needle. These instruments are fitted for test purposes. Engine r.p.m. response topower-lever movement was slightly delayed, resulting in a tendency on my part to over-control initially. To synchronize engine speedsI had to adjust one of the power levers very slightly until the needle of the synchronization indicator ceased to revolve. If the needlewas spinning clockwise, starboard engine power had to be increased; if anti-clockwise, the opposite. No "beat" was hearduntil one engine ran several hundred r.p.m. faster than the other. The simple pneumatically retracted undercarriage folds backwards into the wheel bay. It has twin Dunlop wheels, pneumatic disc brakes with Maxaret, and Dowty shock-absorbers. ' Dowty and Dunlop also feature in the nosewheel assembly, which is pneumatically steered. A great deal of the Friendship's equipment is British-made.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
