shafer@elxsi.dfrf.nasa.gov (06/30/89)
From: shafer@elxsi.dfrf.nasa.gov
I would like to amplify a couple of points that came up in some
recent postings of mine.
I said that the stall/spin/departure characteristics of fighters are
determined by the forebody flow and the stall/spin/departure
characteristics of transport and general aviation aircraft are
determined by the wing flow. It would be more accurate to replace the
word `fighters' with the phrase `aircraft with long, slender, pointed
forebodies' and to replace `transport and general aviation aircraft'
with `aircraft with short, fat, blunt forebodies.' The reason that the
long, slender, pointed forebody has such an effect of the dynamic
characteristic is that powerful vortices are generated by such
forebodies. When these vortices are asymmetric, large asymmetric
forces are generated at the nose of the aircraft. In aircraft with
short, fat, blunt forebodies, only very small vortices, if any, are
generated and the stalling (loss of lift) of the wing provides the
major components of the stall/spin/departure characteristics.
In a later posting, I said that the F-104 didn't originally have nose
cannon or podded cannons for ground attack. This is half right, half
wrong. The F-104 did have a nose cannon right from the beginning, but
the podded cannon were developed later. I was led astray by the F-104N
(N is for NASA).
The F-104N was a model made expressly for the NASA Flight Research
Center (now Ames-Dryden Flight Research Facility) for use as safety
chase and pilot proficiency. They had no cannon, radar, etc, since
these were just extra weight (it's not considered good form for the
safety chase aircraft to shoot down the test aircraft :-)). Three
F-104Ns were delivered. These three aircraft are just about the only
aircraft we ever got brand new, except for some of the X-planes. We
subsequently obtained a number of CF-104s and TF-104Gs--two of the
latter and about five of the former. The armament was removed from
all of these. One single-seater was lost in a crash, one turned into a
reaction-control testbed and is hanging in the National Air & Space
Museum, one is in the Doolittle (?) Museum here at Edwards, and the
others are mothballed here at Dryden. One of the two-seaters is still
flying (it's got about 50 hours left and will then be mothballed) and
the other is mothballed here.
--
M F Shafer shafer@elxsi.dfrf.nasa.gov
NASA Ames Research Center arpa!elxsi.dfrf.nasa.gov!shafer
Dryden Flight Research Facility ames!elxsi!shafer
Of course I don't speak for NASA