Author Topic: Fairing reuse  (Read 543051 times)

Offline IainMcClatchie

  • Full Member
  • ***
  • Posts: 328
  • San Francisco Bay Area
  • Liked: 183
  • Likes Given: 309
Re: Fairing reuse
« Reply #1560 on: 04/26/2018 11:48 PM »
It looks like the sound insulation is applied in the form of individual panels which have some kind of bright reflective edging.  Does anyone know why that would be?  The more obvious way to do it would be to spray foam on the inside, as was done on the outside of the Space Shuttle external tank.

I'm impressed that there appears to be almost no charring.  They're down to the last 50 m/s.  Pretty nice.

Online nacnud

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 2241
  • Liked: 385
  • Likes Given: 191
Re: Fairing reuse
« Reply #1561 on: 04/27/2018 12:48 AM »
The foam on the outside of the ET is thermal insulation rather than sound insulation. I don't know about the fairing insulation but I guess it is much lighter than ET foam and can only be made in sheets that need to be cut up to fit on the fairing inner surface.

Edit: This is what they use on Ariane 5 https://www.plasticsportal.net/wa/plasticsEU~ro_RO/portal/show/common/plasticsportal_news/2006/06_494?doc_lang=en_GB
« Last Edit: 04/27/2018 12:56 AM by nacnud »

Online wannamoonbase

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 3056
  • Denver, CO
    • U.S. Metric Association
  • Liked: 710
  • Likes Given: 1179
Re: Fairing reuse
« Reply #1562 on: 04/27/2018 01:31 AM »
It looks like the sound insulation is applied in the form of individual panels which have some kind of bright reflective edging.  Does anyone know why that would be?  The more obvious way to do it would be to spray foam on the inside, as was done on the outside of the Space Shuttle external tank.

I'm impressed that there appears to be almost no charring.  They're down to the last 50 m/s.  Pretty nice.

Then edging and face maybe to hold the material together.  The very light and whispy insulation is certainly for absorbing sound and vibration.  I was on a project once where we had to do a ton of acoustic testing. A lot of it feels like pure magic, but there is science behind matching material to the types of frequencies you want to absorb. Surface area for high frequencies.  Mass for low bass frequencies. 
Jonesing for a copy of 'Tales of Suspense #39'

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 10174
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 7035
  • Likes Given: 4814
Re: Fairing reuse
« Reply #1563 on: 04/27/2018 03:50 PM »
Off topic (after Chris asked to stop) aetherized
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 4822
  • Michigan
  • Liked: 1919
  • Likes Given: 1
Re: Fairing reuse
« Reply #1564 on: 05/02/2018 06:07 AM »

Online Lars-J

  • Senior Member
  • *****
  • Posts: 4049
  • California
  • Liked: 3344
  • Likes Given: 2110
Re: Fairing reuse
« Reply #1565 on: 05/02/2018 06:09 AM »

Offline mattstep

  • Member
  • Posts: 53
  • Iowa, USA
  • Liked: 21
  • Likes Given: 1962
Re: Fairing reuse
« Reply #1566 on: 05/02/2018 11:58 AM »
New instagram post from Elon Musk:

https://www.instagram.com/p/BiQ5qXnA_OM/?taken-by=elonmusk

Is it traveling wrong-end-first? I had pictured the top of the fairing headed into the wind.

Offline Alastor

  • Full Member
  • **
  • Posts: 266
  • Liked: 147
  • Likes Given: 314
Re: Fairing reuse
« Reply #1567 on: 05/02/2018 12:04 PM »
New instagram post from Elon Musk:

https://www.instagram.com/p/BiQ5qXnA_OM/?taken-by=elonmusk

Is it traveling wrong-end-first? I had pictured the top of the fairing headed into the wind.

You can't necessarily choose.
Or it may be intentional, acting as a low aerodynamic surface to brake. This way it's probably easier to catch it while having a pretty well controlled descent.

It can even be a little bit of both : It sometimes flips if you plan for it not flipping, so it's better to try to have it always flip that way it's more reliable.
I can easily imagine the fairing taking a low aerodynamic position being one of the reasons for the early failures, where the parafoil would suddenly not be enough any more to keep the fairing in the air. 

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32333
  • Cape Canaveral Spaceport
  • Liked: 10987
  • Likes Given: 327
Re: Fairing reuse
« Reply #1568 on: 05/02/2018 01:58 PM »
It looks like the sound insulation is applied in the form of individual panels which have some kind of bright reflective edging.  Does anyone know why that would be?  The more obvious way to do it would be to spray foam on the inside, as was done on the outside of the Space Shuttle external tank.

Yeah, that would make a nice and clean environment for spacecraft

Offline JamesH65

  • Full Member
  • ****
  • Posts: 807
  • Liked: 529
  • Likes Given: 8
Re: Fairing reuse
« Reply #1569 on: 05/02/2018 02:04 PM »
New instagram post from Elon Musk:

https://www.instagram.com/p/BiQ5qXnA_OM/?taken-by=elonmusk

Is it traveling wrong-end-first? I had pictured the top of the fairing headed into the wind.

You could look at that image either as moving left to right or right to left. Depends on the angle from the camera.

Online Lars-J

  • Senior Member
  • *****
  • Posts: 4049
  • California
  • Liked: 3344
  • Likes Given: 2110
Re: Fairing reuse
« Reply #1570 on: 05/02/2018 04:08 PM »
New instagram post from Elon Musk:

https://www.instagram.com/p/BiQ5qXnA_OM/?taken-by=elonmusk

Is it traveling wrong-end-first? I had pictured the top of the fairing headed into the wind.

You assume a direction of flight into the center of the frame. But it might as well be heading out of frame.

Offline kevinof

  • Full Member
  • ****
  • Posts: 572
  • Dublin/London
  • Liked: 345
  • Likes Given: 408
Re: Fairing reuse
« Reply #1571 on: 05/02/2018 04:11 PM »
My assumption (as a sailor), was that it's moving left to right, with the nose rigged purposely high in the event it still has forward velocity when it lands. That way is minimizes water intake into the inside.

New instagram post from Elon Musk:

https://www.instagram.com/p/BiQ5qXnA_OM/?taken-by=elonmusk

Is it traveling wrong-end-first? I had pictured the top of the fairing headed into the wind.

You assume a direction of flight into the center of the frame. But it might as well be heading out of frame.

Offline Skybert

  • Member
  • Posts: 5
  • Norway
  • Liked: 3
  • Likes Given: 2
Re: Fairing reuse
« Reply #1572 on: 05/02/2018 06:07 PM »
Long time lurker, first time poster...

I'm a paraglider pilot and my first reaction to the instagram photo is that it is travelling out of frame. A paraglider has a curved leading edge and often a more or less strait trailing edge. The curved leading edge gives the glider inherent yaw stability.

I think we can see the curved leading edge in the photo.

Offline Swoopert

Re: Fairing reuse
« Reply #1573 on: 05/02/2018 06:43 PM »
Long time lurker, first time poster...

I'm a paraglider pilot and my first reaction to the instagram photo is that it is travelling out of frame. A paraglider has a curved leading edge and often a more or less strait trailing edge. The curved leading edge gives the glider inherent yaw stability.

I think we can see the curved leading edge in the photo.

Freefall parachutes tend to the opposite, to aid opening at terminal velocity, which is a characteristic I would expect this parachute to share. Having said that, I agree that this one does look like it's travelling to the right in this picture. I don't think that we can resolve enough of the image to determine the shape of the edges in this case  (maybe its my bias showing, but i actually see an elliptical trailing edge on the left), but I would bet that the slight triangular bulge on the lower side at the right is the right-hand stabiliser, a non load bearing piece of material that ensures the parachute flies straighter as it opens.

Offline Jnkb

  • Member
  • Posts: 1
  • Liked: 0
  • Likes Given: 2
Re: Fairing reuse
« Reply #1574 on: 05/03/2018 05:11 AM »
New instagram post from Elon Musk:

https://www.instagram.com/p/BiQ5qXnA_OM/?taken-by=elonmusk
Do we know from which mission is that landing?

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7475
  • Everyplaceelse
  • Liked: 1121
  • Likes Given: 7541
Re: Fairing reuse
« Reply #1575 on: 05/03/2018 06:36 AM »
It looks like the sound insulation is applied in the form of individual panels which have some kind of bright reflective edging.  Does anyone know why that would be?  The more obvious way to do it would be to spray foam on the inside, as was done on the outside of the Space Shuttle external tank.

Yeah, that would make a nice and clean environment for spacecraft

A pair of sarc tags probably would have helped here, but I see the software deletes them automatically.:(

Spray on foam is fine for a) Covering large complex areas cheaply b) Not being too worried if any of the surface chips off.
However the insides of payload fairings are (relatively) small and foam fragments dropping into a mechanism (like one of the myriad that control antenna or cell array deployment) are a serious risk to the payload working properly.  Foam insulation is wanted, but at the same time you want the surface to be protected, hence the metal foil.
TBH I'm not really sure how effective that foam really is. It probably cuts the temperature range a bit and some high frequency noise, but a lot of the rocket noise is low frequency, long wavelength stuff. Below 1KHz a foam layer would be 13 inches thick to be 1 wavelength thick.
IMHO they'd be better off evacuating the shell and soft mounting the satellite (such techniques were developed originally for launching payloads on re-purposed ICBM stages with notoriously harsh rides. Soft mounts are used a bit but evacuation never took off. Presumably the tolerances were too tough for a single use object. But a reusable fairing...).
« Last Edit: 05/03/2018 06:42 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline speedevil

  • Senior Member
  • *****
  • Posts: 2291
  • Fife
  • Liked: 1133
  • Likes Given: 1263
Re: Fairing reuse
« Reply #1576 on: 05/03/2018 12:02 PM »
Below 1KHz a foam layer would be 13 inches thick to be 1 wavelength thick.
This assumes the speed of sound in porous absorbers is 340m/s.

This thread claims 111m/s or so may be more realistic, and gives some references I haven't chased up in the literature.

As another point, filling the fairing with Xenon about halves the speed of sound, and filling it with R22 approaches a third.

Evacuation makes the fairing unfortunately heavier.
For a 5.4m diameter fairing, that's around the equivalent stresswise of the whole rocket sitting on it, admittedly symmetrically, but it's going to get quite a lot heavier.

Offline Sohl

  • Full Member
  • **
  • Posts: 241
  • Liked: 77
  • Likes Given: 215
Re: Fairing reuse
« Reply #1577 on: 05/03/2018 04:19 PM »

As another point, filling the fairing with Xenon about halves the speed of sound, and filling it with R22 approaches a third.


Isn't Xenon pretty expensive?  Would filling that big volume cost more than the fairing itself, and not be recoverable?

Offline IanThePineapple

Re: Fairing reuse
« Reply #1578 on: 05/03/2018 05:29 PM »

As another point, filling the fairing with Xenon about halves the speed of sound, and filling it with R22 approaches a third.


Isn't Xenon pretty expensive?  Would filling that big volume cost more than the fairing itself, and not be recoverable?

Xenon is very heavy and very expensive

Offline speedevil

  • Senior Member
  • *****
  • Posts: 2291
  • Fife
  • Liked: 1133
  • Likes Given: 1263
Re: Fairing reuse
« Reply #1579 on: 05/03/2018 06:35 PM »

As another point, filling the fairing with Xenon about halves the speed of sound, and filling it with R22 approaches a third.


Isn't Xenon pretty expensive?  Would filling that big volume cost more than the fairing itself, and not be recoverable?

It's pretty expensive, yes, $1M/fairing. It was more of an aside than a serious suggestion. R22 in principle is nearly free, as a well as almost as nonreactive if that is a concern.

Liftoff weight would increase by around a ton, but as it would mostly be gone by 10km altitude, penalty is limited.

The main point was you probably can't assume speed of sound in air is identical to speed of sound in your foam.

Tags: