Author Topic: CRS-2: Dream Chaser Cargo System  (Read 118938 times)

Offline baldusi

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Re: CRS-2: Dream Chaser Cargo System
« Reply #80 on: 03/20/2015 12:01 pm »
While the CRS-2 RFP talks about docking (IDA) and berthing (CBM) being options, it also says that they need a CBM solution in the mix because of its width. See Answer 20 here: https://prod.nais.nasa.gov/eps/eps_data/160022-OTHER-003-001.pdf so that implies that at least SpaceX or Orbital ATK will get chosen.

CRS-2 RFP calls for (among other things) pressurized cargo up/down per-flight range of: M01 bag 0-10; M02 bag 10-TBP; M03 bag 0-6. How those bags fit with respect to NDS, Cygnus mini-CBM and CBM is shown in the attached figure below.

edit: added ISPR.
for some reason the requirement of removable petals was deleted from the IDSS specification. But that would have allowed for a 1200mm circle. Could you draw it?

Offline joek

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Re: CRS-2: Dream Chaser Cargo System
« Reply #81 on: 03/20/2015 04:37 pm »
updated diagram to show ISPR and NDS 120mm with petal impingement.

Offline JasonAW3

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Re: CRS-2: Dream Chaser Cargo System
« Reply #82 on: 03/20/2015 07:18 pm »
Over all, for those worried about issues with Hypersonic buffeting on the folding wings; so long as the wings fully latch into place, in most cases with supersonic, including some HIGH supersonic aircraft, the system is actually more structurally sound than regular wing spars.

The problem is, making sure those wings mechanically latch into place.  There are a number of cheap and simple systems to check that the latches are engaged.  (If not else, lipstick cameras at each latch to make sure they are visually latched.

As a back up, one could always use Nichromium Springs, stretched out while heated, to help pull the wings into place as they cool.  (As a backup to electric servos to move them into place).

The latches could be made of steel and use neodinium magnets on the other side of the latches to hold the latches themselves in place after they have been put into place by electric servos.

Paranoid?  Not really.  I just figure Murphy is an inventive bugger and as many low mass backup systems that can be used (alternative systems) to act as a back up to a primary system, that would not be affected by a failure of a primary system, should be used.  Simple, low mass backups that won't affect the overall performance, are what I think is the safest route to if not foil Murphy, at least make it REALLY difficult for something to go catastrophically wrong.
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Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #83 on: 03/20/2015 09:06 pm »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
"The laws of physics are unforgiving"
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Offline spacetech

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Re: CRS-2: Dream Chaser Cargo System
« Reply #84 on: 03/20/2015 10:37 pm »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.

Offline Robotbeat

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Re: CRS-2: Dream Chaser Cargo System
« Reply #85 on: 03/20/2015 11:54 pm »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.
Deja vu.
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Offline adrianwyard

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Re: CRS-2: Dream Chaser Cargo System
« Reply #86 on: 03/21/2015 12:08 am »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.

This is getting farcical. But somehow I can't resist... See XB-70.

Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #87 on: 03/21/2015 12:26 am »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.
I think you got the wrong guy... :o
"The laws of physics are unforgiving"
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Offline ChrisWilson68

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Re: CRS-2: Dream Chaser Cargo System
« Reply #88 on: 03/21/2015 12:51 am »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.
Deja vu.

Wait, aren't they folded by the ground crew...

;-)

Offline Burninate

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Re: CRS-2: Dream Chaser Cargo System
« Reply #89 on: 03/21/2015 01:12 am »
While the CRS-2 RFP talks about docking (IDA) and berthing (CBM) being options, it also says that they need a CBM solution in the mix because of its width. See Answer 20 here: https://prod.nais.nasa.gov/eps/eps_data/160022-OTHER-003-001.pdf so that implies that at least SpaceX or Orbital ATK will get chosen.

CRS-2 RFP calls for (among other things) pressurized cargo up/down per-flight range of: M01 bag 0-10; M02 bag 10-TBP; M03 bag 0-6. How those bags fit with respect to NDS, Cygnus mini-CBM and CBM is shown in the attached figure below.

edit: add ISPR; edit: add NDS 120cm; add NDS petals; add M03 bag fit through NDS.
Hold on a minute...

Are those petals really the bounding box?  Or are there petals on both androgynous sides of the port, creating an inscribed circle using six petals?  I'm not certain.

Edit: Attached is an image Wikipedia uses for the NDS.
« Last Edit: 03/21/2015 01:28 am by Burninate »

Offline arachnitect

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Re: CRS-2: Dream Chaser Cargo System
« Reply #90 on: 03/21/2015 01:46 am »
While the CRS-2 RFP talks about docking (IDA) and berthing (CBM) being options, it also says that they need a CBM solution in the mix because of its width. See Answer 20 here: https://prod.nais.nasa.gov/eps/eps_data/160022-OTHER-003-001.pdf so that implies that at least SpaceX or Orbital ATK will get chosen.

CRS-2 RFP calls for (among other things) pressurized cargo up/down per-flight range of: M01 bag 0-10; M02 bag 10-TBP; M03 bag 0-6. How those bags fit with respect to NDS, Cygnus mini-CBM and CBM is shown in the attached figure below.

edit: add ISPR; edit: add NDS 120cm; add NDS petals; add M03 bag fit through NDS.
Hold on a minute...

Are those petals really the bounding box?  Or are there petals on both androgynous sides of the port, creating an inscribed circle using six petals?  I'm not certain.

Edit: Attached is an image Wikipedia uses for the NDS.

If I understand correctly, I think what Joek is showing is a situation where the adapter on station has fixed petals, but the VV petals are removed, so the cargo can be threaded through one triad. Is that possible?

Offline joek

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Re: CRS-2: Dream Chaser Cargo System
« Reply #91 on: 03/21/2015 01:53 am »
Are those petals really the bounding box?  Or are there petals on both androgynous sides of the port, creating an inscribed circle using six petals?  I'm not certain.
If I understand correctly, I think what Joek is showing is a situation where the adapter on station has fixed petals, but the VV petals are removed, so the cargo can be threaded through one triad. Is that possible?
Yes, that was the intent... if one set of petals is removed, the potential size increases.  I do not know if it is possible to remove either set of petals.

Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #92 on: 03/21/2015 12:11 pm »
https://twitter.com/jeff_foust/status/577913004425007104

Lindsey: will do a second Dream Chaser glide test by the end of this year (1st was in October 2013).
It's going to be great to see the bird in the air again! :)
"The laws of physics are unforgiving"
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Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #93 on: 03/22/2015 12:47 pm »
I know they would like to sell concept using a “standard fairing” but I’m curious if they ever considered a modified fairing with slots cut-out for the fins. This would eliminate the need for folding fins; if the wind tunnel would confirm it and the faring integrity maintained without hanging on separation...
« Last Edit: 03/22/2015 01:14 pm by Rocket Science »
"The laws of physics are unforgiving"
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Offline A_M_Swallow

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Re: CRS-2: Dream Chaser Cargo System
« Reply #94 on: 03/22/2015 02:01 pm »
I know they would like to sell concept using a “standard fairing” but I’m curious if they ever considered a modified fairing with slots cut-out for the fins. This would eliminate the need for folding fins; if the wind tunnel would confirm it and the faring integrity maintained without hanging on separation...

Yes. Farings are cheap and the spacecraft does not require the faring to be airtight.

A couple of false fins on the opposite side of the faring may improve the aerodynamics by balance things.

Offline Patchouli

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Re: CRS-2: Dream Chaser Cargo System
« Reply #95 on: 03/22/2015 08:56 pm »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.

Making the folding wing joints safe during reentry would not be much different of a problem then making the flaps and landing gear plasma tight.
In fact it's probably easier then then joints on the flaps since it doesn't need to move during reentry so people are pretty much worried about nothing.


« Last Edit: 03/22/2015 08:56 pm by Patchouli »

Offline Rocket Science

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Re: CRS-2: Dream Chaser Cargo System
« Reply #96 on: 03/23/2015 10:28 am »
OK folks, don’t get all “un-hinged” about the folding fin concept... ;D
You do realize that almost every Navy jet has folded wings, including the F/A-18. I'm pretty sure the F-4 Phantom is the fastest jet with folding wings, with a top speed over Mach 2.

Making the folding wing joints safe during reentry would not be much different of a problem then making the flaps and landing gear plasma tight.
In fact it's probably easier then then joints on the flaps since it doesn't need to move during reentry so people are pretty much worried about nothing.
Once again... You too got the wrong guy...  :o I'm not one of those "worried folks", I'm just looking at options to KISS. :)
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline oldAtlas_Eguy

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Re: CRS-2: Dream Chaser Cargo System
« Reply #97 on: 03/23/2015 04:08 pm »
If the wings are unfolded before arrival at the ISS (which should be the nominal procedure of unfolding the wings after payload sep from LV), then any no latching problems prior to departure from the ISS can be solved.

Offline Comga

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Re: CRS-2: Dream Chaser Cargo System
« Reply #98 on: 03/23/2015 05:21 pm »
If the wings are unfolded before arrival at the ISS (which should be the nominal procedure of unfolding the wings after payload sep from LV), then any no latching problems prior to departure from the ISS can be solved.

I am with Rocket Science:  The folding fins are doable, but ignore KISS.  They ARE a complication.
Thinking of having the astronauts do an EVA to fix an undeployed fin is a HUGE complication.  I cannot see that being considered by NASA.  They would more likely just save the download mass for another download vehicle like Dragon.

But I disagree with Rocket Science's idea of fins on the fairing or through the fairing, wihch would still give the vehicle unique aerodynamic properties, as he acknowledged.  More complications.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline vt_hokie

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Re: CRS-2: Dream Chaser Cargo System
« Reply #99 on: 03/23/2015 08:42 pm »
At some point you've gotta accept a little additional complication in order to move forward and gain desirable long-term capability.  Shortsighted, risk averse thinking that would have us flying expendable tin cans ad infinitum is NASA's biggest problem imo, and why we so desperately need the commercial upstarts to disrupt the status quo.

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