Author Topic: LIVE: Atlas V - X37B Flight 2 - Cape Canaveral - March 5, 2011  (Read 239389 times)

Offline Rocket Science

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I've been wondering about the post-landing center of gravity, based on the landing gear location.  I would have expected more mass on the back end, where the engine is located. 

 - Ed Kyle
Hey Ed!

We have to remember we are dealing with an aircraft in atmospheric flight (not a rocket) in landing mode, so cg is forward of center of lift. Hence the main gear is located about the center of lift (or just rear of). Rocket motors are generally hollow expensive pieces of metal compared to a packed (dense) piston engine. You need to increase AoA at landing as lift decreases allowing a de-rotate and slapdown.

~Robert

http://www.grc.nasa.gov/WWW/k-12/airplane/trim.html

Edit: to add
« Last Edit: 06/19/2012 02:33 PM by Rocket Science »
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Online edkyle99

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Given what we know of the X37's specifications, could you quick-reaction launch an X37 atop an all-solid LV like Minotaur-IV/V or Athena-III?

There is a certain "Athena 3" like possibility that could lift the mass, though I'm not sure it could handle the payload fairing.  It would use a three-segment SRB-like booster, topped by what would essentially be an Athena 2c.  Or variations thereof.  I figure Falcon 9-like capability to LEO, in solid form.  It could fly from KSC, or a new pad at Kodiak.

 - Ed Kyle
« Last Edit: 06/19/2012 02:35 PM by edkyle99 »

Online edkyle99

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I've been wondering about the post-landing center of gravity, based on the landing gear location.  I would have expected more mass on the back end, where the engine is located. 

 - Ed Kyle
Hey Ed!

We have to remember we are dealing with an aircraft in atmospheric flight (not a rocket) in landing, so cg is forward of center of lift. Hence the main gear is located about the center of lift (or just rear of). As you need to increase AoA at landing as lift decreases allowing a de-rotate and slapdown.

~Robert

http://www.grc.nasa.gov/WWW/k-12/airplane/trim.html

Thanks, Robert.  It looks like X-37B has a CG substantially further forward than Shuttle orbiters, based on percent of total body length.

 - Ed Kyle
« Last Edit: 06/19/2012 02:33 PM by edkyle99 »

Offline Rocket Science

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I've been wondering about the post-landing center of gravity, based on the landing gear location.  I would have expected more mass on the back end, where the engine is located. 

 - Ed Kyle
Hey Ed!

We have to remember we are dealing with an aircraft in atmospheric flight (not a rocket) in landing, so cg is forward of center of lift. Hence the main gear is located about the center of lift (or just rear of). As you need to increase AoA at landing as lift decreases allowing a de-rotate and slapdown.

~Robert

http://www.grc.nasa.gov/WWW/k-12/airplane/trim.html

Thanks, Robert.  It looks like X-37B has a CG substantially further forward than Shuttle orbiters, based on percent of total body length.

 - Ed Kyle
Agreed, from what Iíve seen on Shuttle returning hardware was always located aft in the cargo bay.
"The laws of physics are unforgiving"
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Offline Prober

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Offline Prober

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Another X-37B writeup:  China May Be Suspicious of US Air Force's X-37B Space Plane

http://www.space.com/16283-china-x-37b-space-plane-concerns.html

this made Yahoo news but this link is cleaner.
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Offline Ben the Space Brit

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Another X-37B writeup:  China May Be Suspicious of US Air Force's X-37B Space Plane

Heck, there are a lot of people in the west who have their suspicions about the X-37B.  I've ready op-eds from people on both sides of the political divide talking (either negatively or positively) about 'space fighters' and 'space drones'.
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Offline vulture4

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The goal of the X-37 is reusability. Because of the airframe mass its maneuverability in orbit is less than that of a conventional satellite. Fitting it to a DOD mission is tough. One clue to me is the Aerospace Corp. study for DOD which demonstrated that only a fully reusable launch system could significantly reduce the cost of space operations.  http://www.nasa.gov/centers/kennedy/news/beyondnextgen.html
According to study author Jay Penn the DOD is funding studies of a reusable flyback booster stage. A vehicle like the X-37 makes sense as an upper stage for such a reusable launch system.

Offline Jim

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. A vehicle like the X-37 makes sense as an upper stage for such a reusable launch system.

X-37 is a spacecraft and not an upperstage

Offline Jim

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The goal of the X-37 is reusability.

Not true

Offline vulture4

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The goal of the X-37 is reusability.

Not true
Wikipedia:  http://en.wikipedia.org/wiki/Boeing_X-37
"The Boeing X-37 (also known as the X-37 Orbital Test Vehicle) is an American reusable unmanned spacecraft."

Offline GClark

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The goal of the X-37 is reusability.

Not true
Wikipedia:  http://en.wikipedia.org/wiki/Boeing_X-37
"The Boeing X-37 (also known as the X-37 Orbital Test Vehicle) is an American reusable unmanned spacecraft."


What it is is not the same as what its' goal is.

Online edkyle99

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Looking back at various quotes from Air Force and Boeing officials, I find that both typically say that X-37B, especially OTV-2, is a technology demonstrator for reusable space vehicle technologies.  Boeing noted that the demonstration was for "affordable" reusability, while the Air Force said that the return capability was important for low-risk testing of new technologies. 

But note that several years into this program, nothing about the spacecraft itself has, as yet, actually been reused as far as I can tell.  Maybe the payload is the real thing being reused.  Or maybe, as Jim hints, reuse is a ruse.

 - Ed Kyle
« Last Edit: 07/09/2012 01:44 PM by edkyle99 »

Online kevin-rf

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But note that several years into this program, nothing about the spacecraft itself has, as yet, actually been reused as far as I can tell.  Maybe the payload is the real thing being reused.  Or maybe, as Jim hints, reuse is a ruse.

 - Ed Kyle

I believe the up coming X-37b launch will be reusing the first vehicle.

Quick brain fart question, is the OTV designation for the mission or the vehicle.  ie. Will the next launch be OTV-3, or will it be OTV-1 flight 2?
« Last Edit: 07/09/2012 02:18 PM by kevin-rf »
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Offline Kim Keller

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Quick brain fart question, is the OTV designation for the mission or the vehicle.  ie. Will the next launch be OTV-3, or will it be OTV-1 flight 2?

OTV-3 is the mission designation, and it will be a re-flight of the first airframe.

Online kevin-rf

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Quick brain fart question, is the OTV designation for the mission or the vehicle.  ie. Will the next launch be OTV-3, or will it be OTV-1 flight 2?

OTV-3 is the mission designation, and it will be a re-flight of the first airframe.

Thanks, the caffeine had not kicked in yet, I blame the prices at Starbucks.
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Offline Star One

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Looking back at various quotes from Air Force and Boeing officials, I find that both typically say that X-37B, especially OTV-2, is a technology demonstrator for reusable space vehicle technologies.  Boeing noted that the demonstration was for "affordable" reusability, while the Air Force said that the return capability was important for low-risk testing of new technologies. 

But note that several years into this program, nothing about the spacecraft itself has, as yet, actually been reused as far as I can tell.  Maybe the payload is the real thing being reused.  Or maybe, as Jim hints, reuse is a ruse.

 - Ed Kyle

Maybe it's too early into the program for anything definitive to have been decided as per the development of future technologies/vehicles from it?

It's hard for anyone to say when only a limited amount is known outside of DOD circles about the goals & aims of the program.
« Last Edit: 07/09/2012 04:38 PM by Star One »

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