which produces significant drag. The planing hull form requires relatively flat water and significant thrust to achieve take-off speed. ‘At Regent we aim to reduce this thrust
demand by incorporating three modes of operation: from the hull (float) to the hydrofoils (foil) to the aero-wing (flight). This transition affords us a two-stage drag reduction. The vehicle first reduces wetted area from the hull clearing the water and further reduces all hydro drag as it takes off onto the aero wing. This transition directly impacts our power demands keeping us in a favourable range and weight for current battery technology. Akin to the take-off of an AC75, we concentrate on reducing hull drag via length-to-beam ratio keeping our hull form at a low Froude number. Our front foil positioned closest to our centre of gravity provides the majority of our hydrodynamic lift. ‘We control this lift by actuating
symmetric flaperons on the foils which provide lift and, if articulated at different angles, can control roll. In the most recent America's Cup, several concepts were attempted to add flaps to the hydrofoils. The hinge position, stiffness of the foils, fairness of joints or skins and hydraulic actuation all played a pivotal role in drag reduction, avoiding cavitation at higher speeds and aiding controllability. At Regent, these lessons learned are critical in developing a safe and reliable hydrofoil system. On landing, we rely on the hull to provide our deceleration as the foils will be retracted into the hull body. Again, lessons learned from retraction systems developed on the AC50 provide guidance in reducing mass and delivering a reliable retraction system.’
Aero and hydro: two mindsets Baker and Gaynor bring maritime experience to an impressively experienced and talented team of aerospace engineers. Founders Billy Thalheimer and Mike Klinker are both MIT graduates who worked with chief engineer Dan Cottrell at Aurora Flight Sciences, a research subsidiary of Boeing. ‘The meshing of the aerospace and AC engineers has been really interesting to watch,’ Moore says. ‘In the marine world we are very comfortable iterating designs with real world testing. We stopped putting test pilots up in experimental aircraft to see what would happen a long time ago and for very good reasons. As a result the marine engineers have a deep pool of real-world experience to draw upon but the aircraft engineers have an exceptionally diligent design process of validating their models and simulations to make sure that chances of failure are within very clearly defined acceptable ranges. It was impressive to watch the two mentalities mesh and the result was a very quickly executed vehicle that has been very successful in its mission so far.’ The collaboration has created a system
Above: three of the larger ground-effect craft that came out of the Soviet Union Ekranoplan programme between 1950 and 1984 – fromwhich a development path to the Regent ground-effect craft can be traced. Smaller non-military ground-effect craft continue to be built inmodern-day Russia, but a hugemilitary programme ended with the death in 1984 of DefenceMinister Dimitry Ustinov who was the programme's primary sponsor.When flying within 20mof the land or water, ground- effect dramatically increases effective aspect ratio, allowing for stubby short wings, efficiency improved further with these large endplates. In the Ekranoplan programme initial lift-off relied on deep-V water sheddingmain hulls withmultiple spray rails. Today's Regent designs employ amuchmore efficient small foil, while also benefitting frommuch lightermodern constructionmethods. However... these brutal- looking Soviet craft successfullymet the brief... and some were very very fast. The legendary Caspian SeaMonster (centre) was almost 100min length, weighed over 550-tonnes and could comfortably exceed 400 knots. It also featured as standard a nuclear-capable armaments' delivery system... while you were all sleeping soundly
that is agile with strong checks and balances that ensure both safety and repeatability.
It’s a boat, not a plane Ground effect aeroplanes have been around for a long time but Moore notes that Regent is combining new technology with a fresh approach. ‘Flight control systems have been developing so rapidly in the last few decades. We’ve all seen it in the drones we buy for our kids. You're not actually flying the craft, the computer
is, and you are telling it which way to go. The electric propulsion also adds an interesting element. It allows you to use many small propellers instead of a few big ones. This distributes the flow from the thrust evenly over the wing creating a blown wing effect like apparent wind in sailboats giving more lift earlier and allowing for slower take off speeds.’ Given that Regent’s design is a WIG
that lands on her hull, she is technically a boat and therefore governed by the US Coast Guard. This leads to fewer
SEAHORSE 85 �
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