Post by The EnlightenmentPost by Peter StickneyKuchemann didn't have anything to do with the Area Rule. The
"Kuchemann Coke Bottle" came from n attempt tpo have the fuselage
contours of his swept-wing model match the local flowfield - not the
same thing at all. The idea that overall cross-section distribution
should as closely as possible conform to an ideal shape didn't occur
to him.
I don't see how you could say "its not the same thing at all".
It's quite simple, really, What Kuchemann was doing didn't have
anything to do with the Area Rule.
Post by The EnlightenmentKuechmann came up with a coke bottle shape, the same solution as Whitecombes
area Rule, and it had the same effect.
You lack understanding. The Area Rule has nothing to do with a "Coke
Bottle" shape, per se. The way that it works is that you get the
minimum amount of drag if the overall cross section of your aircraft
approxiates the ideal shape. That doesn't mean "Coke Bottle", but
that's one way of doing it. The F-102A's Area Rule application, btw,
wasn't just waiisting the fuselage. The airframe was dramatically
lengthened, and the Yellow Canary extensions - those pointed fairings
on the aft dside besire the afterburner nozzle, were added at the aft
end. (The Yellow Canary extensions, btwm, were resonsible for the
"Marylin Monroe" apellation for the restrung F-102. It wasn't a
reference to her waist measurement, but to other uh, pointed ogivial
fairings.)
Many aircraft, especially those designed after the early 1960s conform
to the Area Rule without any obvious "waisting".
Post by The EnlightenmentIt was comming from a different 'perspective' but it produced the same
solution albeit with a lower level of understanding.
No, it was an attempt to reduce the interfernece drag between the wing
and the fuselage. That's not the same thing at all. The form drag
doesn't become a factor until up around Mach 0.9 - faster than either
Kuchemann's drawing or any tunnel that existed before 1948-49. (The
Germans did have at least one "bump" tunnel, which allowed a transonic
section without incredibly (And for the Germans after 1943,
impossibly) high power consumption, but they didn't have slotted-wall
tunnels, which prevented choking.
Post by The EnlightenmentAt least two German designes used this primitive flow field area rule which
admitedly wasn't as well elucidated.
Again, that wasn't the Area Rule.
Post by The Enlightenment<http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia
/Wave_drag>
"Fuselage shaping was similarly changed with the introduction of the
Whitcomb area rule. Whitcomb had been working on testing various airframe
shapes for transonic drag when, after watching a presentation by a German
researcher in 1952, he realized that the Sears-Haack body had to apply to
the entire aircraft. This meant that the fuselage needed to be made
considerably skinnier where the wings met it, so that the cross-section of
the entire aircraft matched the Sears-Haack body, not just the fuselage
itself. "
(don't know who the German researcher was)
Adolph Busemann, as a matter of fact. (Busemann, BTW, didn't come up
with the idea of the swept wing - he was a bug un using biplane wings
to cancel the shock wwaves. The swept wing was the idea of a Redia
Aeronautica Gerneral who attended the High Speed FLight conference
where Busemann presented his paper.) Busemann's point, that jogged
Whitcomb, was that at subsonic speeds, the airpflow could be
considereed as a series of tubes with varying cross sections, the
cross section changine with airspeed adn pressure. At sonic speeds,
these "streamtubes" had a constant cross section.
This, combined with the new tools available - the slotted transonic
tunnel built by Whitcombe and John Stack, adn the Schlieren photos that
it could produce, were what allowe Whitcombe to see what was
happening, and dedice the phenomenon. Without that visual reference,
nobody had picked up on what has happening. Not Whitcombe, up to that
point, or Stack, Hayes, Busemann, or Kuchemann.
check out:
http://history.nasa.gov/SP-4219/Chapter5.html
(It helps if you spell Kuchemann's name right.)
Post by The EnlightenmentDietrich Küchemann arrived at the solution by studying airflow, notably
spanwise flow, over a swept wing but even he later commented (now working at
the British RAE at Farnborough) that Whitcomb's statement of the problem,
and solution, was considerably more clear and decisive than his own.
Post by Peter StickneySo, I'd have ot count home out. There was a theoretician (Hale, or
Haley, I think it was) who also had done some work which could have
led to hte propunding of the Area Rule. But neither man was able to
make the conceptual leap that Whitcombe did to develop teh full
principle.
Possibly it could have been Dipl.-Ing. H. von Halem who was Küchemann's
partner?
No, Wallace D. Hayes, in fact.
Post by The EnlightenmentPost by Peter StickneyKuchemann did make a further contribution to tranonic aerodynamics -
the "anti-shock body" or "Kuchemann carrot" - a large canoe shaped bdy
at the trailing edge of the wing, which was supposed to delay shock
formation. Indeed, it did do that, but the drag reduction that it
produced was more than offset by the increased wetted area of the
carrot. Example of the Kuchemann Carrot are teh trailing edge pods of
the Tu-16 and itd derivatives, the pods on the wing of the
H.P. Victor, and the Convair 990 airliner. If, like Tupolev, you had
to have the volume to stick something else in - like the Standard Issue
Soviet Era rough-field landing gear), it wasn't too bad, but it didn't
pay off in practice.
All these aircraft were quite succesfull. These 'carrots' are in fact a
form of the 'area rule' as is the swept wing itself which also leads to a
gradual increase in cross sectional area.
The Tu 95 Bear used them and is still the fastest seving Truboprop (as fast
and high flying as a B52 in some of its versions)
The Yu-95 owes its performance more to the unique and very clever
NK-12 variable-pressure ratio "supercharged" turboprops, which can deliver
sea level power at 40,000', an astonishing reduction gearbox which
turns those props at 750 rpm, keeping the tip speeds manageable, and
crews that don't ming going deaf from the "contra-clatter". The
"carrots" are more thaere to hold the landing gear, I'd say - the
cruiise L/D is much worse than that of a B-52 (More drag), and,
compared with its contemporary Buff, it's down about 100 mph (160 kph)
in speed, and 3,00 miles (5,000 km) in range.
Post by The EnlightenmentThe Convair 990 is still faster than any other airliner.
Not even close - and not even among its contemporaries. The 990
exhibited no measurable performance advantage over the earlier CV-880
(Convair model 22), and was out-run by the Boeing 720 and 727. The
747 was also able ot show it a clean pair of heels. The CV-880 and
990 series were quite uneconomical to run. They had no speed
advantage over their contemporaries, and were small and short-ranged to
boot.
Post by The EnlightenmentOnly the B747 comes close and that is because the famous jumbo 'hump' was
in fact a form of deliberately introduced area ruling. Rather than waisting
the fueselage the designer bulges the fueselage ahead of the wing.
Which would move the maximum thickness distribution too far forward,
and make the nose too "blunt". I'd say tht the 747's hump owes more
to its origins as a C-5 competitor, where the disire was to have a
large, unobstructed cargo hold.
--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster