From kls Tue Jan 26 23:47:07 1993 Newsgroups: sci.aeronautics.airliners Path: news From: raveling@Unify.com (Paul Raveling) Subject: Nose-down attitude X-Submission-Date: Tue, 26 Jan 93 03:31:11 GMT Message-ID: Approved: kls@ohare.Chicago.COM Organization: Unify Corporation (Sacramento) Sender: kls@ohare.Chicago.COM X-Submission-Message-Id: Date: 26 Jan 93 23:47:07 PST Last week, while various combinations of our news server and network were in shambles, Geoff Miller wrote... > The fuselage of the DC-8 has a pronounced nose-down attitude on the ground, > which is especially noticeable with the stretched Super 60 and -70 models. > Does anyone know the reason for this? It occurs to me that the designers > might have had the possibility of a fuselage stretch in mind, ... Without knowing actual engineering history, I'd note that the DC-8 is among the more long-legged airliners and would speculate that these could be reasons for that choice: 1. Safety: Having a nose-down attitude on the ground reduces the wing's AOA on landing rolls. This puts more weight on the gear, which enables better braking action... [braking force = coefficient of friction * vertical force] and the difference probably is most significant on wet, icy, or snowy runways. The same effect helps directional stability as well as braking. 2. Economics: A shorter nose gear is lighter. In the DC-8's case it probably translates to either (a) ability to carry a couple extra paying passengers or (b) leaving behind a proportional amount of fuel, which reduces gross weight some more. 3. Safety (minor): A nose-down attitude improves visibility over the nose slightly for taxiing, admittedly a very minor effect though. ------------------ Paul Raveling Raveling@Unify.com