Re: Blackbird lore

[Air Force Jayhawk]

On Thu, 24 Jul 2003 16:27:58 -0400, "Lawrence Dillard"
> wrote:

>Dear ng:
>
>Can anyone supply details on NASA's flight profiles when using the
>Blackbird? I am interested in confirming/denying a report I heard/read to
>the effect that to economize on fuel use, NASA would climb the Blackbird to
>a given height, dive it through the "sound barrier" then continue to
>accelerate while climbing to operational altitude. If true, could someone
>detail the height at which the dive began? Thanks.
>

That's a standard technique when trying to minimize your climb time
with a supersonic cruise speed. Trying to climb through Mach 1 is
brutal (Drag rise in the transonic region is tremendous...minimizing
time in that region is the key).

AFJ

[Kyle Boatright]

> > wrote:
>
> >Dear ng:
> >
> >Can anyone supply details on NASA's flight profiles when using the
> >Blackbird? I am interested in confirming/denying a report I heard/read
to
> >the effect that to economize on fuel use, NASA would climb the Blackbird
to
> >a given height, dive it through the "sound barrier" then continue to
> >accelerate while climbing to operational altitude. If true, could someone
> >detail the height at which the dive began? Thanks.

20 years ago, I read an article in Popular Science where the writer got a
backseat ride in an SR. He indicated that they pitched over into a moderate
descent in the low 30xxx foot range to accelerate through the transonic
region where drag is at its maximum.

KB

[Kurt R. Todoroff]

In order to climb to a given altitude in the minimum amount of time, an
aircraft must fly a maximum specific excess power (maximum P_s) profile. This
is often referred to as the Rutowski climb profile. It is unique to each
aircraft type.

On the chart, Rutowski mapped a profile that corresponded to the points where
excess power lines were tangent to constant energy states. The resultant
profile may "appear" counter intuitive, ie. diving to gain altitude, however,
some bits and pieces of the previous posts are actually valid components of a
maximum P_s climb.

I recommend you search for Rutowski. There are a few well written descriptions
of his work and theory.





Kurt Todoroff


Markets, not mandates or mob rule.
Consent, not compulsion.

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[Mary Shafer]

On Thu, 24 Jul 2003 16:27:58 -0400, "Lawrence Dillard"
> wrote:

> Dear ng:
>
> Can anyone supply details on NASA's flight profiles when using the
> Blackbird? I am interested in confirming/denying a report I heard/read to
> the effect that to economize on fuel use, NASA would climb the Blackbird to
> a given height, dive it through the "sound barrier" then continue to
> accelerate while climbing to operational altitude. If true, could someone
> detail the height at which the dive began? Thanks.

That's the dipsydoodle and the USAF started it. You can go supersonic
flying straight and level (i.e. no dipsydoodle) but you'll be out of
fuel fairly quickly. The dipsy just lets you make potential energy
cheaply and then turn it into kinetic energy.

Mary

--
Mary Shafer Retired aerospace research engineer

"A MiG at your six is better than no MiG at all."
Anonymous US fighter pilot