Author Topic: Fairing reuse  (Read 478056 times)

Offline obi-wan

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Re: Fairing reuse
« Reply #1620 on: 05/18/2018 09:31 PM »
I'm skeptical about the merit of fairing reuse. It is something every other launchers can implement at any time. The development cost is not prohibitive, there is nothing that would prevent its development. But nobody has try in space flight history.
 I guess it's just a marketing gimmick by elon musk. The question would be how much added cost they can tolerate rather than how much it can save.

Wrong in a bunch of ways. 

1.  a)SpaceX fairings are significantly different from other manufacturers'.  Because of the way that SpaceX has chosen to horizontally integrate the encapsulated payloads with their rockets, their fairings are built to support much higher forces than is normal (i.e. weight of the payload is, at times, supported by the fairing).  This means that they are much more rigid (as well as heavier).  And as a result, they may have a distinct advantage over other fairings in controllably surviving reentry without as much modification.  To see this difference, watch how wobbly/flappy other fairings are on jettison.
{rest snipped because this is what I'm replying to}

I know this has been discussed before on this site, but no, no, NO!!! The fairing DOES NOT _EVER_ support the payload, on any vehicle, for any reason! Check out the payload user's guides for any launch vehicle, including F9. ALL the loads for the payload are taken through the payload attach fitting (PAF), which is the ring at the top of the upper stage to which the payload attaches (typically with a Marman band or other low-shock separation device). The payload volume is defined as a dynamic envelope which the payload can never exceed under the worst case loading. That's because the payload fairing will never enter that volume under its worst case loading. If the payload fairing ever touches the payload, you have an indeterminate loading condition where the payload is assuming some of the fairing loads, or vice versa. There is no way to predict the loads in that case, so there's no way to qualify the payload or fairing if that happens.

When the F9 is horizontal, the payload is cantilevered from the PAF. The fairing is cantilevered from its mounting fixture around the upper stage. Most launch providers have a very large piece of GSE that will hold the integrated fairing/payload cantilevered from the mounting face for integration to the launch vehicle if they use horizontal integration.

I can't say categorically that SpaceX does not use the fairing as a lifting point for payload integration, although that would require either that every fairing is designed for the mass and inertia of its specific payload, or that every fairing is designed to take the loads of the heaviest payload F9 is capable of flying, either of which would be surprising as compared to just making some GSE to take the loads. But I will say categorically that the payload never, ever touches the inside of the fairing, as payload designers would find it impossible to definitively calculate those loads and verify against the (nondeterministic) models.

Offline deruch

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Re: Fairing reuse
« Reply #1621 on: 05/19/2018 09:29 AM »
I'm skeptical about the merit of fairing reuse. It is something every other launchers can implement at any time. The development cost is not prohibitive, there is nothing that would prevent its development. But nobody has try in space flight history.
 I guess it's just a marketing gimmick by elon musk. The question would be how much added cost they can tolerate rather than how much it can save.

Wrong in a bunch of ways. 

1.  a)SpaceX fairings are significantly different from other manufacturers'.  Because of the way that SpaceX has chosen to horizontally integrate the encapsulated payloads with their rockets, their fairings are built to support much higher forces than is normal (i.e. weight of the payload is, at times, supported by the fairing).  This means that they are much more rigid (as well as heavier).  And as a result, they may have a distinct advantage over other fairings in controllably surviving reentry without as much modification.  To see this difference, watch how wobbly/flappy other fairings are on jettison.
{rest snipped because this is what I'm replying to}
I can't say categorically that SpaceX does not use the fairing as a lifting point for payload integration, although that would require either that every fairing is designed for the mass and inertia of its specific payload, or that every fairing is designed to take the loads of the heaviest payload F9 is capable of flying, either of which would be surprising as compared to just making some GSE to take the loads. But I will say categorically that the payload never, ever touches the inside of the fairing, as payload designers would find it impossible to definitively calculate those loads and verify against the (nondeterministic) models.

This is what I was talking about.  Not that the payload ever touches the fairing but that loads are carried through it when, post encapsulation, they break it over from vertical to horizontal and then integrate it with the rocket.  Once it is integrated, the loads are either entirely or almost entirely carried by the rocket.  But SpaceX doesn't (or at least didn't in the past) use a specialized bit of GSE to keep all the forces running through the PAF.  They used the HIF cranes with lift points on the fairing which means the load path partially runs through the fairing.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Comga

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Re: Fairing reuse
« Reply #1622 on: 05/19/2018 08:25 PM »
I'm skeptical about the merit of fairing reuse. It is something every other launchers can implement at any time. The development cost is not prohibitive, there is nothing that would prevent its development. But nobody has try in space flight history.
 I guess it's just a marketing gimmick by elon musk. The question would be how much added cost they can tolerate rather than how much it can save.

Wrong in a bunch of ways. 

1.  a)SpaceX fairings are significantly different from other manufacturers'.  Because of the way that SpaceX has chosen to horizontally integrate the encapsulated payloads with their rockets, their fairings are built to support much higher forces than is normal (i.e. weight of the payload is, at times, supported by the fairing).  This means that they are much more rigid (as well as heavier).  And as a result, they may have a distinct advantage over other fairings in controllably surviving reentry without as much modification.  To see this difference, watch how wobbly/flappy other fairings are on jettison.
{rest snipped because this is what I'm replying to}
I can't say categorically that SpaceX does not use the fairing as a lifting point for payload integration, although that would require either that every fairing is designed for the mass and inertia of its specific payload, or that every fairing is designed to take the loads of the heaviest payload F9 is capable of flying, either of which would be surprising as compared to just making some GSE to take the loads. But I will say categorically that the payload never, ever touches the inside of the fairing, as payload designers would find it impossible to definitively calculate those loads and verify against the (nondeterministic) models.

This is what I was talking about.  Not that the payload ever touches the fairing but that loads are carried through it when, post encapsulation, they break it over from vertical to horizontal and then integrate it with the rocket.  Once it is integrated, the loads are either entirely or almost entirely carried by the rocket.  But SpaceX doesn't (or at least didn't in the past) use a specialized bit of GSE to keep all the forces running through the PAF.  They used the HIF cranes with lift points on the fairing which means the load path partially runs through the fairing.
Please read the previous post with more care.
Your statements are false.
« Last Edit: 05/19/2018 08:26 PM by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline deruch

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Re: Fairing reuse
« Reply #1623 on: 05/20/2018 05:34 AM »
This is what I was talking about.  Not that the payload ever touches the fairing but that loads are carried through it when, post encapsulation, they break it over from vertical to horizontal and then integrate it with the rocket.  Once it is integrated, the loads are either entirely or almost entirely carried by the rocket.  But SpaceX doesn't (or at least didn't in the past) use a specialized bit of GSE to keep all the forces running through the PAF.  They used the HIF cranes with lift points on the fairing which means the load path partially runs through the fairing.
Please read the previous post with more care.
Your statements are false.

Here's the lift and breakover of the Jason-3 mission.

https://www.flickr.com/photos/nasakennedy/23776528834/
Quote
KSC-20160111-PH_TNN0001-0006

In the SpaceX Payload Processing Facility at Vandenberg Air Force Base in California, the Jason-3 satellite is fully encapsulated in its payload fairing. With this step complete, Jason-3 will be mated to a SpaceX Falcon 9 rocket at Vandenberg's Space Launch Complex 4. Built by Thales Alenia of France, Jason-3 will measure the topography of the ocean surface for a four-agency international partnership consisting of NOAA, NASA, Centre National d’Etudes Spatiales, France’s space agency, and the European Organization for the Exploitation of Meteorological Satellites.

https://www.flickr.com/photos/nasakennedy/24322264661/
Quote
KSC-20160111-PH_TNN0001-0007

In the SpaceX Payload Processing Facility at Vandenberg Air Force Base in California, the payload fairing containing the Jason-3 satellite has been rotated to horizontal in preparation for mating to a SpaceX Falcon 9 rocket at Vandenberg's Space Launch Complex 4. Built by Thales Alenia of France, Jason-3 will measure the topography of the ocean surface for a four-agency international partnership consisting of NOAA, NASA, Centre National d’Etudes Spatiales, France’s space agency, and the European Organization for the Exploitation of Meteorological Satellites.
Photo credits: NASA/Thiep Nguyen and Christopher Wiant

Maybe things have changed or, for heavier payloads, they do things differently but we haven't seen any evidence of this [excluding Dragon which is treated differently and does have a unique breakover fixture].  When coupled with the manner that they support the fairings during roll-out and while the rocket is horizontal on the pad prior to being erected, I think the point about load paths still stands.  Of course, if you have any evidence of relevant changes (even if it's just passed along info from those who have first hand knowledge) I'd be very interested to see/hear it.
« Last Edit: 05/20/2018 05:53 AM by deruch »
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline OxCartMark

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Re: Fairing reuse
« Reply #1624 on: Today at 03:17 AM »
So I saw that the fairings went up and I saw them fall back down and I see that Mr. Steven is in port.  Those are the basic facts.  Can anyone fill in the details?

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