Quote from: speedevil on 05/25/2018 03:26 pmQuote from: edzieba on 05/25/2018 02:14 pmThe two main techniques for preventing seawater damage to an object, and the only two that are 100% effective, are a) keep the object out of the seawater and b) keep the seawater out of the object. The fairings need to be porous (vented) to they can be brought from 1ATM or near 0ATM and back without bursting or collapsing, which is at odds with the need to seal them against seawater ingress. Keeping them out of the seawater in the first place is preferable to a complete fairing redesign to avoid internal pockets.The internal pressure in vacuum is only 14PSI, or somewhere slightly over that due to heating.14PSI, in the context of a CF honeycomb structure, may be entirely structurally irrelevant and containing it may be less work than venting it.Do you know if the CF honeycomb is safe in vacuum. Your logic above, alone, is not valid. 14 psi = 10 tonnes/sqm. Which just as convincingly sounds like the sort of force (OK tonnes force is not SI unit) that would expand a honeycomb to destruction!
Quote from: edzieba on 05/25/2018 02:14 pmThe two main techniques for preventing seawater damage to an object, and the only two that are 100% effective, are a) keep the object out of the seawater and b) keep the seawater out of the object. The fairings need to be porous (vented) to they can be brought from 1ATM or near 0ATM and back without bursting or collapsing, which is at odds with the need to seal them against seawater ingress. Keeping them out of the seawater in the first place is preferable to a complete fairing redesign to avoid internal pockets.The internal pressure in vacuum is only 14PSI, or somewhere slightly over that due to heating.14PSI, in the context of a CF honeycomb structure, may be entirely structurally irrelevant and containing it may be less work than venting it.
The two main techniques for preventing seawater damage to an object, and the only two that are 100% effective, are a) keep the object out of the seawater and b) keep the seawater out of the object. The fairings need to be porous (vented) to they can be brought from 1ATM or near 0ATM and back without bursting or collapsing, which is at odds with the need to seal them against seawater ingress. Keeping them out of the seawater in the first place is preferable to a complete fairing redesign to avoid internal pockets.
I have made considerably less advanced honeycomb than this, and the delamination strength would have been well over 140, rather than 14 PSI.
The two main techniques for preventing seawater damage to an object, and the only two that are 100% effective, are a) keep the object out of the seawater and b) keep the seawater out of the object.
Quote from: DistantTemple on 05/25/2018 07:27 pmQuote from: speedevil on 05/25/2018 03:26 pmQuote from: edzieba on 05/25/2018 02:14 pmThe two main techniques for preventing seawater damage to an object, and the only two that are 100% effective, are a) keep the object out of the seawater and b) keep the seawater out of the object. The fairings need to be porous (vented) to they can be brought from 1ATM or near 0ATM and back without bursting or collapsing, which is at odds with the need to seal them against seawater ingress. Keeping them out of the seawater in the first place is preferable to a complete fairing redesign to avoid internal pockets.The internal pressure in vacuum is only 14PSI, or somewhere slightly over that due to heating.14PSI, in the context of a CF honeycomb structure, may be entirely structurally irrelevant and containing it may be less work than venting it.Do you know if the CF honeycomb is safe in vacuum. Your logic above, alone, is not valid. 14 psi = 10 tonnes/sqm. Which just as convincingly sounds like the sort of force (OK tonnes force is not SI unit) that would expand a honeycomb to destruction!14PSI is also 14 pounds per square inch. Or perhaps a couple of pounds per linear inch of aluminium honeycomb edge if that honeycomb has cells around 8mm. It would be quite hard to get a CF/Al joint that bad.I have made considerably less advanced honeycomb than this, and the delamination strength would have been well over 140, rather than 14 PSI.It is unclear if the honeycomb/CF they are using is structurally airtight to 14PSI without extra work - it is at least plausible.If other loads are much larger than 14PSI in the structure, and they likely are, the ability to resist exploding in vacuum may be free.
Quote from: edzieba on 05/25/2018 02:14 pmThe two main techniques for preventing seawater damage to an object, and the only two that are 100% effective, are a) keep the object out of the seawater and b) keep the seawater out of the object. I am wondering, are there any technique that the fairings could be washed clean if they where to be subjected to seawater? I'm thinking of submersion in distilled water until no trace of sodium chloride could be detected? If that is the case one could skip the chase boat and personnel and probably get a even cheaper solution to faring reuse.
The company is already working on a successor for the black panels that it used at the Tesla launch. 'We are working on a hydrophobic version, to keep the pieces afloat when they fall into the sea. Reuse is one of the hobbies of SpaceX. '
From Recticel maakt cruciale onderdelen voor raketbedrijf Elon MuskQuoteThe company is already working on a successor for the black panels that it used at the Tesla launch. 'We are working on a hydrophobic version, to keep the pieces afloat when they fall into the sea. Reuse is one of the hobbies of SpaceX. '
Falcon 9 fairing halves deployed their parafoils and splashed down in the Pacific Ocean last week after the launch of Iridium-6/GRACE-FO. Closest half was ~50m from SpaceX’s recovery ship, Mr. Steven.
Quote from: SpaceXFalcon 9 fairing halves deployed their parafoils and splashed down in the Pacific Ocean last week after the launch of Iridium-6/GRACE-FO. Closest half was ~50m from SpaceX’s recovery ship, Mr. Steven. https://mobile.twitter.com/SpaceX/status/1002268835175518208
In the image under chute, some damage can be seen to the left side trailing edge.
Quote from: Helodriver on 05/31/2018 08:25 pmIn the image under chute, some damage can be seen to the left side trailing edge.I don't see that, could you please circle it for me?
Those brown stripes on the second pic... that's a well-toasted marshmallow.
Yeah, there's a fair bit of damage visible to both parafoils, which really makes how close they got to Mr Steven (in order to get those pre-landing shots) seriously impressive. An extremely resilient design, once they work out the optimum opening sequence to protect them, they'll be on Mr Steven no bother. That many broken lines on a sport canopy and it would be totally unflyable!