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2015 FAI F3A World ChampionshipsTeam Canada -Technical Report

By Colin Chariandy

Local conditions

The contest was held at the Dubendorf Airbase just outside of Zurich Switzerland from 7 th to 15th August. Climatic and altitude condition changes were relatively benign to our competitors and little effort was required to adapt aircraft set up or flying styles.

Some practice sites available were however significantly different from typical North American sites. Available space in around Zurich is allocated to Farming and the Team had to accommodate smaller runways situated on or adjacent to mountainous areas. This was a challenge all accepted and overcame within the first few flights.

Biplanes

The Biplane proliferation continued at the 2015 WC with the majority of competitors opting to fly biplanes including seven of the top ten finishers. Notable exceptions were the reigning and eight time World Champion, CPLR and the US National Champion, 4th place competitor Andrew Jesky.

Despite significant diversity in the biplane designs the popular choice was the Accuracy Biplane by Naruke. The Accuracy and Seba’s Prometheus represented the mid-size end of the scale for biplanes whereas Brukman’s Sensation and Susuki’s Zebec were smaller and Jason Shulmans’ Epic bipe was on the ‘Mega’ end of the scale.

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The speed envelope for the Biplanes appeared to be more critical than that of the monoplanes particularly for lateral stability. Holding heading even in relatively calm conditions presented an additional challenge to the pilots. The workload required to keep the biplanes pointed in the right direction generally appeared to be greater that that required for the monoplanes.

Naruke’s prototype Accuracy flown by Onda differed from the original model by the addition of significant area on the aft fuselage and reduced wing area, apparently intended to improve lateral stability.

Gernot’s Sensation sported a large add on area below the fuse on the lower edge of the vertical stabilizer. Jason’s Epic simply had the largest stabilizer possible, bordering on IMAC size.

The majority of the Biplane pilots also flew large fast patterns mitigating the effect of lateral instability.

Monoplanes

Though fewer in number at the contest the monoplane exhibited a maturity in design that allowed pilots a significant speed and pattern size range as well as a very stable platform. With the common style being large fast patterns the monoplane design was in no way disadvantaged and several converted the use of the mono to great results.

Although fewer design innovations appeared at this World’s, the monoplane evolved larger and lighter fuselages and CPLR introduced a wing tip design that defies traditional Aero Engineering concepts for aerobatic planes.

Lateral authority has been significantly improved even without the use of T-cans on several designs. The Accuracy Mono introduced the use of fuselage strakes while the Allure by Brian Herbert makes use of a very large light weight fuselage with a ventral strake on the bottom.

Akiba’s combination of a large T-can with a vertical canard appeared to give the Fantasista tremendous rudder authority.

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Aero tweaks

There were several interesting design solutions to aero problems ranging in complexity from stick on vortex generators to complex control systems.

The Hungarian junior added these vortex generators to his Caelestia for added rudder authority.

Akiba’s Fantasista sported inboard Ailerons, stepped wing, vertical and horizontal stab plan forms, flying horizontal stabilizer and a lateral canard that was synchronized with the rudder. The result was a spectacular flying monoplane.

Seba’s Prometheus monoplane added a T-can to the bottom of the fuse and his biplane had a total of eighteen strakes distributed on the bottom of the upper wing panel and top of the lower wing panel. One can only assume that the designer believes the spanwise flow exits only in the area between the wing panels.

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Japans premier designer Naruke introduced flared elevators in the Accuracy designs for improved linearity in pitch control. This is likely to be seen in newer designs coming out of Japan.

Power Systems

The overwhelming majority of the power systems used remained in favour of Electric systems with only two of the finalist running glow motors, YS185DZcdi’s in the case of Onda and Christophe. YS motors ran flawlessly and always appeared to have excess power and torque available.

Plettenberg and Hacker electric motors were the most prolific power systems. The relatively new OS Belt drive system, OS OMR4043, appeared in several airplanes including the Japanese team member’s Suzuki and Akiba. These systems demonstrated good power while being quiet. Akiba flew

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the semi-finals sequence using 4400mAHr packs indicating that these power systems are likely also efficient.

Contra Systems

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The Contra-drive systems performed well under the light wind conditions experienced at this World Championships. The Systems have improved in power output after the last two years of propeller and gear reduction improvements. The Brenner Sharp Contra system was more frequently used but the Hacker CR and new CRS RS (Ralph Schweizer) Systems also made appearances in airplanes including Wolfgangs Matt’s Kunzit.

The CRS RS System was notably quieter than the others while being less mechanically complex internally.

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