FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1957
1957 - 0944.PDF
44 FLIGHT Handling the Thruxton Jackaroo Impressions of a New and Improved Tiger Moth By C. M. LAMBERT THE Thruxton Jackaroo, which should receive its full Certi-ficate of Airworthiness by next month, is claimed to be thecheapest four-seat private aircraft in the world. In eithercrop-dusting or four-seat version it sells at £1,095 complete, with nil engine hours, ex works at Thruxton, near Andover. Whicheveris bought, a conversion kit to turn it into the other one is available for £150. Practically the whole original Tiger Moth structure isretained intact; and Tiger spares, which are available almost every- where, can therefore be used. The overhaul life of the engine is1,500 hr and overhauls cost £150. The simplicity and robustness of the original Tiger are retained(though the Jackaroo is not aerobatic) but its already pleasant handling characteristics have been somewhat improved byvery simple refinements, such as the sealing of the elevator and fin gaps and the addition of streamlining fairings at the roots of bothupper and lower mainplanes. This is no flash in the pan; orders from abroad for no fewer than 150 Jackaroos are stated to be onhand, 50 of them from South Africa. Last week I was able to fly one of the first two Jackaroos whichare now completing certification trials. The machine I tried was the first crop-sprayer, G-AOEY, which had been specially remadeinto a four-seater, because the prototype was still full of test instrumentation. I had last flown a Tiger about eight years agowhen I made my first solo in one very shortly before converting to Chipmunks; and I was most surprised at the number of charac-teristics which took me straight back to those days; it was like hearing a song hit of so many years ago. The Jackaroo is normally flown solo from the front left seat(Tiger soloists are back-seat drivers). Getting into the front seat presents some problems at first, but two well-placed handles andsome practice make all the difference, and only skirted types might find continuing difficulty. The canopy structure appears strongand rigid and the long doors are strongly hinged and safe in operation. The new canopy, a flattened forward nose decking andan ample single-piece windscreen give excellent visibility on the ground and in the air. I was particularly pleased to see how littlethe wings and the narrow wooden roof panel got in the way, especially during the final approach. Plenty of tinted plastic glazingkeeps the sun off well. Controls and instruments are virtually the same as those of the Tiger, except that the slot-locking lever hasbeen moved out on to a centre-section strut, to be reached by sliding back the side window. The ignition switches are movedto the main instrument panel, which now has room for several more dials. The direct-indicating fuel gauge is still on top of thetank itself and can be seen from the front by leaning some way back in the seat. The original Tiger flying controls and seats are located intandem on the port side; and two small but adequate upholstered seats are added to starboard in the four-seater. They can be quicklyremoved to make room for freight. In the agricultural version, the pilot sits in die rear left seat and has the hopper across the cabinin front of him. The canopy is replaced by a flush decking through which the instruments can still be seen. Maximum payload, inaddition to pilot, in either version is 550 lb. Fuel is sufficient for 3 hours at the normal 1,900 r.p.m. cruising setting, which givesa speed of 85 m.pJi. One of the considerable improvements in handling charac-teristics achieved by fairings and sealing is a barely detectable stall. I seem to remember the Tiger stalling in some reasonablydecisive way, but the Jackaroo gives one or two warning jogs and then goes downhill with its nose firmly up in the air for as longas the stick is held firmly back. Release of backward pressure results in instant recovery in a fairly pronounced dive. At full power a slight climb can be maintained without difficulty at nomore than 28 kt; and position error at this speed is reported to be only one or two knots. The Jackaroo has, under protest, entereda spin to the right when firmly held to it, but "Doc" Stewart of Boscombe Down, who is doing the testing, has not yet succeededin producing a spin to the left at all. Increased frontal area of the Jackaroo fuselage has made limiting speeds very much harder toattain. Since there are no flaps or other moving parts to give large trimchanges the lever-and-spring-bias elevator trim arrangement is effective and its range is never exceeded. "Built-in" drag and avery low engine idling speed produce a very respectable rate of descent during the approach and the very large rudder allowspronounced side-slipping to lose speed and height. Only the length of the pre-touch-down float betrays the absence of lift-spoiling devices. A most intriguing Jackaroo feature is the spring-centring andbiasing device added to the rudder control circuit. It consists of two springs attached to the rudder pedals and located on a movablebar. A hand lever is used to offset the centre position of the springs to provide some rudder trimming. The rudder is thus restrainedduring normal flight and directional stability benefits. Even so, if aileron is applied with the rudder bar free, some rudder movementcan be seen and a good deal of yawing in die opposite direction occurs. But hands-off cruising for long periods is possible. At firs*, I thought that the rate of climb, even with a singleoccupant and less than full fuel load, left something to be desired in view of the possible 550 lb payload. But I soon discovered that,firstly, the climbing attitude was deceptively shallow and, secondly, that the aircraft was very sensitive to climbing speed. Once I wasup in the mist away from misleading ground-references, I found the right climbing speed somewhere around 52 kt I.A.S. andreached 3,500ft in a very short time indeed. An officially observed climb, at full load, from 1,000ft to 2,000ft took 1 min 55 sec,giving 500ft/min. The Jackaroo will climb hands-off. Take-off, landing and taxying present no problems at all. Firstly,the widening of the fuselage has led to a corresponding widening of the undercarriage track which makes the machine very muchmore stable laterally on the ground in comparison with the Tiger. The ride is remarkably comfortable and steering with the tail-skiddoes not seem to have suffered significantly. On landing, the Jackaroo sits down like a lady, apparently with little tendency tobounce. On take-off, the tail can be raised, with a firm forward pressure on the stick, immediately full power is applied, and swingis negligible when running straight into wind. My only real complaint about the Jackaroo was a rather highnoise level, but this is caused, apparently, by the lengthened exhaust pipe which ends just aft of the cabin. It concentrates noisethere and either shortening or lengthening should give considerable relief. But after an hour's flying, most of it at high power settings,I did not feel any undue fatigue. The controls and instruments are so few and so basic that thenon-Tiger man spends most of his pre-take-off checking time trying to find things he feels he must "have forgotten. The TigerMoth's great advantage from every point of view is its simplicity and cheapness; and the Jackaroo retains all this but adds a coveredcockpit for four people and improved controls. Soon, five or six will be produced each month at Thruxton, with Bruntons WireMills, Musselburgh, Scotland, and Bruton Engineering Company, Ltd., of Twickenham, Middlesex, making components. Britten-Norman spraying gear (Flight, March 23, 1956) is to be fitted where appropriate. The Jackaroo seems set for a future it richlydeserves. The agricultural Jackaroo,'left, showing how the widened fuselage accommodates both hopper and pilot under a Hush removable decking This machine, rapidly converted to a four-seater, was flown by the author. Right, the tour-seat cabin is well filled. Top transparencies are tinted and doors open forwards. "Flight" photographs
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
