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Old 06-26-2017, 01:50 AM
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Default New F9 grid fins!

Hello All,

The Iridium satellites-carrying Falcon 9 that flew from Vandenberg Air Force Base today (this article also includes a video of the launch and Stage 1 landing: http://spaceflightnow.com/2017/06/2...et-in-two-days/ ) was the first to fly with the new titanium grid fins (see: http://spaceflightnow.com/2017/06/2...ts-fin-upgrade/ and also the attached photograph below). Also:

These new, maintenance-free fins—which will be necessary on the triple-barreled Falcon Heavy—don’t self-ignite during re-entry as the original aluminum grid fins have. Their slightly larger size and scalloped profile improve their control authority, enabling stages to land in heavier winds. (This higher-wind landing capability was amply demonstrated today, as the descent and landing portion of the video shows--the first stage shook violently and its grid fins were very active, as it fought the low-altitude winds to land on the heaving deck of the drone ship!)
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Old 06-26-2017, 07:54 AM
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They are getting so good it's becoming "old hat" to some folks like the shuttle launches. I'm looking forward to seeing Falcon Heavy.
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Old 06-26-2017, 02:51 PM
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A user on nasaspaceflight posted a link to an interesting paper dealing with the design of those scalloped leading edges of the new grid fins Novel High-Performance Grid Fins for Missile Control at High Speeds: Preliminary Numerical and Experimental Investigations . The link is a pdf, the image comes from that pdf. Those peaks help with supersonic flow through the grid.
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Old 06-26-2017, 10:36 PM
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Quote:
Originally Posted by tbzep
They are getting so good it's becoming "old hat" to some folks like the shuttle launches. I'm looking forward to seeing Falcon Heavy.
That's exactly what Elon Musk hopes for (as he said, "Oh--another landing."), because that will mark the point at which rockets and spaceships *really* become part of the everyday world, instead of their flights being viewed as stunts. No one who sees one fly in person (or who, as we do here, understands how challenging those "routine" events really are) will ever become blasé about launches and space flights. (Having seen, heard, and *felt* the Saturn IB of Apollo-Soyuz lift off from across the Banana River, I can say from experience that such intense light, noise, and artificial seismic activity are impossible to take for granted--ditto for the Black Brant VB, Taurus-Orions, and Black Brant 12s that I saw from a much closer vantage point at the Poker Flat range!)
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Old 06-26-2017, 10:47 PM
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Quote:
Originally Posted by rocketguy101
A user on nasaspaceflight posted a link to an interesting paper dealing with the design of those scalloped leading edges of the new grid fins Novel High-Performance Grid Fins for Missile Control at High Speeds: Preliminary Numerical and Experimental Investigations . The link is a pdf, the image comes from that pdf. Those peaks help with supersonic flow through the grid.
Thank you for posting the paper and the illustration! I had suspected that the modified planforms of the new grid fins' elements would improve their transonic and supersonic performance ("flat" grid fins "choke" and produce a lot of drag when the local airflow within the 'waffle gaps' reaches Mach 1, and the airfoils' shallowly swept-back shock waves interact within the gaps; until the local airspeed increases significantly, the grid fins act almost like flat plates).
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Old 06-27-2017, 08:30 AM
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Quote:
Originally Posted by blackshire
Having seen, heard, and *felt* the Saturn IB of Apollo-Soyuz lift off from across the Banana River, I can say from experience that such intense light, noise, and artificial seismic activity are impossible to take for granted--ditto for the Black Brant VB, Taurus-Orions, and Black Brant 12s that I saw from a much closer vantage point at the Poker Flat range!
Having experienced a 9 inch by 144 inch solid from about 150 feet distance, it is enhanced by proximity!

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Old 06-28-2017, 12:42 AM
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Quote:
Originally Posted by Jerry Irvine
Having experienced a 9 inch by 144 inch solid from about 150 feet distance, it is enhanced by proximity!

That looks (and sounds, "dimensions-wise") like a Thiokol Tomahawk motor or a very similar "derivative"--Arthur C. Clarke's comment about the "ringing silence" after a burn sounds like what such a close-up experience would be like.
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http://www.lulu.com/product/cd/what...of-2%29/6126511
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