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Blackbird lore
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 |
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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 |
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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. Remove "DELETEME" from my address to reply |
#4
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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 |
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