Uncrewed Systems Technology 048 | Kodiak Driver | 5G focus | Tiburon USV | Skypersonic Skycopter and Skyrover | CES 2023 | Limbach L 2400 DX and L 550 EFG | NXInnovation NX 100 Enviro | Solar power focus | Protegimus Protection

91 Limbach L 2400 DX and L 550 EFG | Dossier by using an adapter shaft and a rotary vibration damper, as well as the existing connections on the 550’s crank. Limbach’s engineers also made an adapter plate for fastening the housing to the engine. The generator’s housing was then screwed to the adapter plate. Limbach also reports that ePropelled’s iPS (intelligent Power System) and EES (Electronic Engine Starter) module have been installed on the L 550 EFG. The iPS enables consistent transmission, conversion and monitoring of electrical power to onboard systems such as avionics, payloads and batteries. The EES provides the engine starting function while also being able to restart the engine during flight independently of technicians or other crewmembers, if for instance a fault occurs or the engine has been stopped for the aforementioned noise-related reasons. Single-speed gearbox The L 550 EFG’s new gearbox adds roughly 13 kg of weight, for a total mass of 28 kg. In exchange, the end-user gets a torque output at the transmission output shaft and propeller mount of about 96 Nm. That comes through the transmission approximately halving the output shaft’s speed from the crankshaft’s 7500 rpmmaximum continuous rate to 3378 rpm. The gearbox’s efficiency is estimated at around 93%. “Naturally it will be a case-by-case matter that UAV manufacturers will need to decide on, if the higher efficiency for their propeller is worth the extra weight, or if they want a lighter engine and a less efficient prop,” Simmerkuss says. An earlier design of this gearbox was developed in the 1990s for one of Limbach’s carburetted two-strokes. In response to customer requests it has been redesigned and adapted for the L 550 EF. The design features a mounting plate at the rear, through which the L 550’s output shaft is inserted and bonded to a coupling made of high-strength aluminium. Within this initial stage of the gearbox is an iron trigger wheel that serves as an rpm sensor, a toothed gear for engine starting, and an aluminium spacer ring between the two. Simmerkuss adds that in due course the starter gear will be rendered obsolete by the ePropelled starter/generator, although some customers have indicated that they might opt for both starting systems for redundancy. Uncrewed Systems Technology | February/March 2023 The L 550 EFG’s new single-speed gearbox raises its output torque to 96 Nm; the total weight with the gearbox is 28 kg You can put battery energy into the starter/generator and have it function as a motor, to add potentially up to 4 kW extra shaft power to the engine