Hamid,

It was a pleasure meeting you a couple years ago when I had the pleasure
of flying Brent's IV-P for the Chelton video.

Q. Just curious why you made these changes?  What were you trying to achieve?  A. Drag reduction.

Q. What kind of engineering analysis did you do on the strength of the fuselage after the modifications?
A. Analyze the materials removed for the repair.  Q. What kind of aerodynamic analysis did you do?
A. Until they destroy all the wind tunnels because computational methods
are accurate enough, we'll have to do with the past experience of others
and educated guesses.  Marketing probably had a bigger influence on the
fuselage than any aerodynamic analysis.

Q. What were the qualifications of the person doing the analysis?
A. I have neither degrees in aerodynamics or engineering, but I do have
friends who do.   As far as the structure is concerned, I talked to Carsten Sundin
about my proposal prior to cutting, and to make a very long conversation
short, "Treat it as a repair".  There are standards for repairs and
there is probably very little in the composite world that cannot be
repaired, including changing the materials.
I talked to Greg Cole who designed the wings and tails about the
mod.  Paraphrasing, "You can only be assured of a reduction in drag
based on the surface area removed, because you can't quantify the
reduction in the coefficient of drag you will surely gain".  I believe
we also came up with the standard external com antenna costing a minimum
of 3 knots at normal Legacy cruise.
Before I purchased my kit I also talked to Greg about concerns I
saw for the existing wing/tail/fuselage junctures.  He agreed that it
visually appeared that the fuselage was probably tapering to rapidly
near the trailing edge of the wing.  They later tufted the fuselage and
came up with mods that Andy Chiaveita is marketing to fix those problem
areas.  Andy was kind enough to share the info with me.
Burt Rutan is not the kind of guy that accepts, "It can't be
done", and neither am I.  Burt had told me not to do any of the mods
that I suggested to him for the Vari-Eze I wanted to build.  Years
later, after I passed his re-engined Defiant, we spent a lot of time
looking at and discussing all of those changes.  Mike Melville later
wrote of my Vari-Eze as being the fastest in the world.  It was
certainly the lowest drag.
Gary Hubler's Cassutt, Mariah, is the reigning formula one
champion.  He and his father came to me a few years ago wanting to solve
a stability problem.  "A new tail would fix it, but a new wing would
also get them into the gold heats at Reno".  Here's the secret folks.
Don't forget that to  fly the tight course, more than half the race is
in excess of 3.5 G.  I can't take the credit, though.  Gary flies the
course so well he would probably win with the second place airplane.
Now, if I could just get them to through away that draggy old Cassutt
fuselage, they'd finally top John Sharp's records.

The need for speed and capable steed will get you a nick-name.


John "Boom Boom" Chambers

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