Author Topic: SpaceX Falcon Landing legs - General Discussion Thread  (Read 248109 times)

Online meekGee

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #40 on: 01/12/2014 11:21 pm »
Close up with details.
@Lar: the leg should be where I've put the black area.
Why don't you think the tab circled here in red is the anchor for the legs? It looks right to me.
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

I think it is 45 degrees off.

The hold-downs are along the principal directions of the FH.  (That is, there are 8 hold-downs.  3 on each side core and 2 on the center core)
The legs are along the 45-degree directions, so that they don't interfere with each other while stowed.
This means the leg anchor points are back along the principal directions.

* There is an additional small amount of clocking on the side cores, as seen on SpX's FH page, on the bottom view.  I'd love to see that assembly first hand.

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Offline Comga

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #41 on: 01/13/2014 12:43 am »
Close up with details.
@Lar: the leg should be where I've put the black area.
Why don't you think the tab circled here in red is the anchor for the legs? It looks right to me.
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

I think it is 45 degrees off.

The hold-downs are along the principal directions of the FH.  (That is, there are 8 hold-downs.  3 on each side core and 2 on the center core)
The legs are along the 45-degree directions, so that they don't interfere with each other while stowed.
This means the leg anchor points are back along the principal directions.

* There is an additional small amount of clocking on the side cores, as seen on SpX's FH page, on the bottom view.  I'd love to see that assembly first hand.

That makes no sense to me.  The basis of the Falcon 9 is the octoweb, with eight fold rotational symmetry.  Any distinction of 45 degrees would involve very fine details.

Your discussion of the Falcon Heavy has no bearing on what is in the image. It appears that there are four hold-downs on this Falcon 9, not eight.  The two in the image seem to be at right angles.  It makes great sense that the leg mounts, of which there are also four, are offset by 45 degrees to avoid interference. 

We would all like to see the assembly details.  What we will actually get to do is to pour over launch photos like these.
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Offline AncientU

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #42 on: 01/13/2014 01:08 am »
Close up with details.
@Lar: the leg should be where I've put the black area.
Why don't you think the tab circled here in red is the anchor for the legs? It looks right to me.
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

I think it is 45 degrees off.

The hold-downs are along the principal directions of the FH.  (That is, there are 8 hold-downs.  3 on each side core and 2 on the center core)
The legs are along the 45-degree directions, so that they don't interfere with each other while stowed.
This means the leg anchor points are back along the principal directions.

* There is an additional small amount of clocking on the side cores, as seen on SpX's FH page, on the bottom view.  I'd love to see that assembly first hand.

That makes no sense to me.  The basis of the Falcon 9 is the octoweb, with eight fold rotational symmetry.  Any distinction of 45 degrees would involve very fine details.

Your discussion of the Falcon Heavy has no bearing on what is in the image. It appears that there are four hold-downs on this Falcon 9, not eight.  The two in the image seem to be at right angles.  It makes great sense that the leg mounts, of which there are also four, are offset by 45 degrees to avoid interference. 

We would all like to see the assembly details.  What we will actually get to do is to pour over launch photos like these.
meekGee was referring to the FH holddown scheme
« Last Edit: 01/13/2014 01:09 am by AncientU »
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Offline Joffan

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #43 on: 01/13/2014 01:26 am »
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

There should be some structure at the point where the telescoping piston attaches to the body. That's what I understood "D" to be referring to.
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Online meekGee

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #44 on: 01/13/2014 02:20 am »
Close up with details.
@Lar: the leg should be where I've put the black area.
Why don't you think the tab circled here in red is the anchor for the legs? It looks right to me.
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

I think it is 45 degrees off.

The hold-downs are along the principal directions of the FH.  (That is, there are 8 hold-downs.  3 on each side core and 2 on the center core)
The legs are along the 45-degree directions, so that they don't interfere with each other while stowed.
This means the leg anchor points are back along the principal directions.

* There is an additional small amount of clocking on the side cores, as seen on SpX's FH page, on the bottom view.  I'd love to see that assembly first hand.

That makes no sense to me.  The basis of the Falcon 9 is the octoweb, with eight fold rotational symmetry.  Any distinction of 45 degrees would involve very fine details.

Your discussion of the Falcon Heavy has no bearing on what is in the image. It appears that there are four hold-downs on this Falcon 9, not eight.  The two in the image seem to be at right angles.  It makes great sense that the leg mounts, of which there are also four, are offset by 45 degrees to avoid interference. 

We would all like to see the assembly details.  What we will actually get to do is to pour over launch photos like these.

Right - go back and look at the holddowns of the F9, and infer from that on the FH.

In principle, there are two options.

a) Have two "end" hold-downs along the long axis of the base (x) and then 2 more (side) on the short axis (y) for each core - so a total of 8.   (Looking like the schematic for a Propane molecule.... :)

b) Have 4 hold-downs per core, at 45 degrees to the principal axes.  But then the two inner hold-downs of each of the side cores would interfere with those of the center core.

From the picture, it looks like option A.

If that's the case, then the legs (as depicted in the drawings) will attach at the same angles as the hold downs.

So why are there 8 attachment points?  Perhaps in order to transfer the rocket from one setup to another.  Imagine that the T/E has to register and hold the rocket somewhere, so when it is erect, the other 4 bracket match the hold downs - right?
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Offline Avron

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #45 on: 01/13/2014 02:24 am »

So why are there 8 attachment points?  Perhaps in order to transfer the rocket from one setup to another.  Imagine that the T/E has to register and hold the rocket somewhere, so when it is erect, the other 4 bracket match the hold downs - right?

Take a look at cambrianera's pics a few posts back.. I think he nailed it.. octaweb handling attachments during assembly

Online meekGee

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #46 on: 01/13/2014 03:24 am »

So why are there 8 attachment points?  Perhaps in order to transfer the rocket from one setup to another.  Imagine that the T/E has to register and hold the rocket somewhere, so when it is erect, the other 4 bracket match the hold downs - right?

Take a look at cambrianera's pics a few posts back.. I think he nailed it.. octaweb handling attachments during assembly

yup - nice detail in these picture.  During assembly though, conceivably you could use just the 4 "regular" attachment points meant for the hold-downs. (as you, for example, attach the engines to the octa-web)

But when you have a full rocket, and you want to attach it to the hold-downs - where do you hold it until the attachment is made?  You need to have a second set of attachment points in order to do the hand-off.

It is pretty elegant.
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Offline cambrianera

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #47 on: 01/13/2014 08:27 am »
Found this pic, courtesy of Lars_J: http://forum.nasaspaceflight.com/index.php?topic=32930.msg1100855#msg1100855
Shows things clearly.

About the "straight" eyetabs, using them during assembly means you aren't stressing the holddown eyetabs (I mean, you really don't want dents or wear on them).
GH2 in the pic had a different, simplified octaweb assembly and has no "straight" eyetabs.
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Offline Avron

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #48 on: 01/13/2014 10:51 am »
Found this pic, courtesy of Lars_J: http://forum.nasaspaceflight.com/index.php?topic=32930.msg1100855#msg1100855
Shows things clearly.

About the "straight" eyetabs, using them during assembly means you aren't stressing the holddown eyetabs (I mean, you really don't want dents or wear on them).
GH2 in the pic had a different, simplified octaweb assembly and has no "straight" eyetabs.


Thats a great job, the attachments really stick out with that color coding..  So the vertical tabs are part of the holddown system. That is different to the pin into Vehicle of F9.0

I wonder if they may also serve as part of the core attachment system of FH.. or is that taking an elegant system to a whole new level.

Offline cambrianera

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #49 on: 01/13/2014 11:45 am »
So the vertical tabs are part of the holddown system. That is different to the pin into Vehicle of F9.0

I wonder if they may also serve as part of the core attachment system of FH.. or is that taking an elegant system to a whole new level.

That's what I believe, they are very strong attachment points.
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Offline Garrett

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #50 on: 01/13/2014 01:10 pm »
Everyone seems to be focused on the bottom parts.   I'm more interested in Parts B & D in this photo.
Attached is a photo from the CASSIOPE launch. I've circled an area in red that might be the point you marked 'B', i.e. the telescope attachment point. It's about 1 meter higher than in the image you posted. Don't pay much attention to the "SpaceX" decal as it's not in the same position or of the same scale in either image.
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This is a really good thread.

I'll do my part by seeking official answers, for the purpose of an article.

Offline RedSky

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #52 on: 01/13/2014 03:34 pm »
Remember when SpaceX released the video of the fairing separation test?  Does anyone think they might reveal a similar test video of leg deployment prior to an F9 v1.1 being seen with legs attached? (even if it will not land on land that first mission).  They must have tested deployment of at least one leg on some type of mockup.  I would think such a video would skyrocket interest in that launch by the general public and news media.

Offline MP99

Yes, they might do RTLS but with a target in the ocean a few miles out from the shore - before going for a land landing.
Perhaps, but Musk was quoted saying they were seeking permission to land back at the Cape for CRS-3.

He was saying that a few months ago, yes. But without any GH2/F9R-1 test flights in McGregor or NM, I think that is a very remote possibility at this point. A couple of GH2 hops will of course change that if they happen.

Judging based on the post launch Q&A of Orbital; the company knows 2014 plans extremely well.   Moving this thinking over to the SpaceX side.   Legs or no legs, landing etc. should have been all timed out Sept-Oct 2013.

So the only information we will get is once SpaceX wishes to reveal it.   Don't believe a couple of hops would make any difference regarding CRS-3.

ISTM more likely that they are still doing development and / or build work towards their RTLS goal, and they'll fly legs if they happen to be ready in time not to delay that flight. (And NASA doesn't object).

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Offline cambrianera

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #54 on: 01/13/2014 06:03 pm »
Everyone seems to be focused on the bottom parts.   I'm more interested in Parts B & D in this photo.
Attached is a photo from the CASSIOPE launch. I've circled an area in red that might be the point you marked 'B', i.e. the telescope attachment point. It's about 1 meter higher than in the image you posted. Don't pay much attention to the "SpaceX" decal as it's not in the same position or of the same scale in either image.
What you marked as "telescope attachment point" is too high on the stage. That is the place of the tip-latch.
Someone posted in another thread a nice animation from KSP, I don't remember where.
In the meantime, get this one, simplified but clear (I hope).
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Offline MTom

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #55 on: 01/13/2014 06:31 pm »
Found this pic, courtesy of Lars_J: http://forum.nasaspaceflight.com/index.php?topic=32930.msg1100855#msg1100855
Shows things clearly.


Found a better image.
This could be ok for the legs --> red line is the axis for one leg.

http://www.neowin.net/forum/topic/1167603-spacex-updates-thread-4-f9-fh-dragon/
« Last Edit: 01/13/2014 07:54 pm by MTom »

Offline MTom

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #56 on: 01/13/2014 07:03 pm »
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

Not at the "D" Label. It should be at the high of "D".
The attachment point  of the telescope - and the telescope itself - is covered from the leg in closed position.


Offline Lars_J

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #57 on: 01/13/2014 07:10 pm »
I don't see anything at the "D" label.  That seems to be for the dimension.  What is it you think you see there?

Not at the "D" Label. It should be at the high of "D".
The attachment point  of the telescope - and the telescope itself - is covered from the leg in closed position.

That picture is not necessarily a good way to judge how high up the telescoping cylinder will attach. A measurement of the base points to the start of the groove in the leg (for the cylinder in its collapsed form) would be much more accurate. You need to imagine how this leg will be attached to the core when it is folded up.
« Last Edit: 01/13/2014 07:12 pm by Lars_J »

Offline WmThomas

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #58 on: 01/13/2014 07:20 pm »
I'm curious as to whether the legs will have some other material on the foot-side. Surely some kind of flexible and strong footing will be needed. Carbon Fiber isn't that great at handling hard impacts, is it?

I'd be happy to learn more.

Offline cambrianera

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Re: SpaceX Falcon Landing legs - General Discussion Thread
« Reply #59 on: 01/13/2014 07:31 pm »
I'm curious as to whether the legs will have some other material on the foot-side. Surely some kind of flexible and strong footing will be needed. Carbon Fiber isn't that great at handling hard impacts, is it?

I'd be happy to learn more.

This is a close up of the pic posted by MTom few min ago: you can see the metal structure that clearly is the body of the foot.
I think also the contact pad on the tip can be hardened metal (something like ball bearing steel).
« Last Edit: 01/13/2014 07:33 pm by cambrianera »
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