Product Test – Tri-Vector Nav Plotter

calculator market is the Tri-Vector, born and developed in Sydney.

First launched in Australia, the Tri-Vector is finding a ready market and has already sold in quantity as far away as Alaska is a growing export drive.

The Tri-Vector story began when its co-designer, University of NSW staffer Barry Wing got caught in thickening weather near the Blue Mountains while on a routine flight.

Heavy cloud buildups necessitated quick heading alterations to stay VFR. Came an added complication Barry’s destination airfield notified closure through cloud. A quick diversion was the order of the day.

Barry told AADR he was thoroughly trained on the disc type calculator, but mounting pressures on that flight had him landing at the end of his sortie telling himself there must be a better way.

His first task the following day was to discuss the problem with co-worker Dick Frost, a mathematician with no flying experience.

First off the rank was a study of flying training stats., which brought to light some startling and not-too-happy facts:

• About 50 per cent of all those who start flying training drop out before completion of their course. Industry evidence and opinion supported the view that most of these dropouts were because of the inability to cope with navigation, not with flying – a generally accepted fact, with, in our opinion failure in meteorology as·a strong supplementary cause.

• Particular greyness-centred round wind vector problems, and corrections. (We would privately take issue with this latter assertion; any school worthy of the name always makes damn’ sure that ALL students fully understand ALL nav. problems, with emphasis on triangles of velocity, before going on with anything else).

Dick, with Barry’s factual presentation, eventually met the prime objective to produce a device, small enough to be managed e in a light aircraft cockpit, capable of handling all the common VFR problems, and give a much clearer the portrayal of the vector forces arising from wind – preferably so the user can see the effect of these forces directly on a WAC chart.

Dick produced the prototype computer. Barry immediately recognised it as a quantum leap forward in ease of use, learning and understanding. Unisearch, the company operated by the Uni. of NSW for the commercialisation of research efforts spawned within the Uni., secured the idea with international patent protection.

Exclusive manufacturing licence was eventually granted to the Victoria-based firm of W & G Precision Instruments, which filled requirements in the fields of precision work, export markets’ access and professional product. Final development criteria included ensuring that the product incorporated every desirable feature possible, and that the instruction book accompanying the device would be clearly understood by the newest trainee as well as by experienced pilot navigators.

What eventually hit the market has been a clear plastic a device consisting of three major components; a track fan, airspeed link and wind protractor linked by a metal swivel and adjustable circular nut.

With the marketing came clear design features:

Completeness: all normal VFR problems can be rapidly solved by the Tri-Vector – or by reference to the instruction book. The device makes no assumptions about the user’s prior knowledge of navigation. When device, instruction book and WAC chart are used together, they user can become proficient in VFR nav. concepts and practice. The TriVector is easy to learn and leads to solid understanding of the process of navigation.

Ease of Use: Tri-Vector can be fitted into a pilot’s shirt pocket and used with one hand if necessary. We took issue with these claims. Trying to fit the device into our shirt pocket left most of the track fan sticking way out like a plastic dress hankie and it fell on the cockpit floor more than twice when we bent forward.

Single-handed use – most student pilots who start their vexes (and indeed some PPL holders) leave the traditional 30 per cent of their brains and one hand on the deck when they take-off. We found it difficult in our in-flight evaluation in a moderate chop, to precisely position all the relevant parts with one hand, chart clipped onto a clipboard and balanced on our thighs.

The claim that all details superfluous to VFR conditions have been removed to help speed up interpretation, and leave the clearest view possible of the WAC at all times, was justified. So were other more minor claims.

Durable: All markings and graduations have been engraved into the plastic, and enamel-filled for long readability. All plastic surfaces have been separated so they only rub on areas irrelevant to Tri-Vector operation. We noticed that the spindle nut on the wind protractor had left very distinct scratch marks over the vital time curve scales, after an hour or so’s use during our evaluation.

Approaching the device with an open mind – and trying to forget our upbringing with Douglas, Kane, a myriad old WACs crisscrossed with painstakingly drawn triangles of velocity during bygone days, and our currently-used and eminently satisfying Sifeba plotter – we found that an hour’s honest study and practice produced definite results in the the flight planning phase, using the Tri-Vector.

The instruction book is indeed comprehensive, and prefaces the whole exercise with an admirable glossary of terms used in navigation.

The claim that this device has been the nett result of more than two years’ input from practising pilots and mathematicians is fully apparent.

The Tri-Vector’s track fan is etched with a distance scale (for WAC measurements), a ground speed scale graduated from 40 to 220, and a further G/S scale for vector problems.

Across the fan are time curves. Swivelling freely from the fan’s base is an airspeed link for reading either true airspeed (TAS) or indicated airspeed (IAS).

A wind speed scale is attached to the airspeed link by a spindle nut.

Sounds complicated, but the device is amazingly compact for the information it feeds.

Simple exercises solved by the Tri-Vector include the straight-out reading of distance, and ground speed calculation plus calculation of flight time along a course leg.

Wind vector triangle solutions are arrived at without fuss.

Our only argument with the device at this stage was that degree graduations were too rough for us to make really accurate readings – but as mentioned before, we were dragged up in an atmosphere of absolutely pinpoint and hair’s breadth navigation as only the RAF can inculcate. . .

Finding heading and ground speed, given the desired course and wind vector was likewise no trouble. We took issue with the word “course” when in fact we knew it as “track”, in the instruction book’s glossary and explanations – but times are changing every tick of the clock.

Course (track?), speed and position location, given heading and wind, was another easy exercise, as was finding a new wind.

All in all, we found the Tri-Vector to be a worthy entrant in the Nav. Stakes. Its strong points are undoubtedly in the flight planning and navigation training spheres; we had some trouble in keeping departure and destination points aligned with the device in practice, in flight, and unless one has the instruction book handy (presuming you’re a sprog pilot) it’s a bit of a lottery lining up the correct wind vector without a really accurate degree-by-degree compass rose on the wind protractor.

And after all, if you don’t teach trainees really accurate work from the outset, they’re more prone to adopt sloppy methods in later flying. At a recommended retail price of $24. 50 at the time of testing, we feel the Tri-Vector is a worthwhile addition to anyone’s flight bag and look forward to the Mk 2 Tri-Vector with modifications.

A rider to this evaluation is a standing ovation for whoever designed the instruction book. It backs up the TriVector most admirably, with words of two syllables, plus boasting a height/temperature correction scale for IAS – something the Tri-Vector doesn’t do.