Sir - I have lectured for 25 years on flight safety and, with reference to the Viscount article (Flight International, 20 December-2 January, P30), the hot-air anti-ice system does not necessarily supply sufficient heat to the tail-section leading edges in severe icing conditions, unless the fuel flow to engines two and three is increased so much that engines one and four must be throttled back close to idle during approach. Iced leading edges may cause the stabiliser to stall when landing flaps are selected.
I fail to see the reason for research in to developing laminar-flow wings for transport aircraft, because laminar flow must be nearly impossible to maintain in the complex flow region at wing roots and wingtips, and in the turbulence and vibration environment at engine installations and behind propellers. This leaves the area outboard of the outboard propeller tip to a chord distance from the wingtips as a potential laminar-flow region. A few dead insects at the leading edges, leading-edge wear and tear, ice, and other types of contamination would turn low-drag laminar-flow profiles into high-drag turbulent profiles, however.
AAGE ROED
Chief Investigator Of Civil Aviation Accidents, Sweden (ret)
Forslov, Sweden
Source: Flight International
