SpaceX Falcon 9 : Iridium NEXT Flight 2 (June 25, 2017) : Discussion

[russianhalo117]

Yeah that makes sense. Maybe analogous to leading edge vortex generators.

http://www.aerochapter.com/notes.php?name=Module%208&inst=1&nid=6&top=99

correct its very similar approach. Missiles with grid fin for stability and steering use varying designs and the technology was later transferred to aircraft for noise reduction and fuel efficiency.

[old_sellsword]

Well as we've now seen it's a block 4 & not 3 which makes more sense to me as far as using the new fins is concerned.

Where have we seen that this first stage is Block 4? New grid fins doesn't mean it's a new Block.

Read the posts just up above my OP for the evidence.

They talk about the new grid fins, as far as I can tell (always helpful to quote relevant comments).

New grid fins do not imply that this first stage is Block 4.

[Star One]

Well as we've now seen it's a block 4 & not 3 which makes more sense to me as far as using the new fins is concerned.

Where have we seen that this first stage is Block 4? New grid fins doesn't mean it's a new Block.

Read the posts just up above my OP for the evidence.

They talk about the new grid fins, as far as I can tell (always helpful to quote relevant comments).

New grid fins do not imply that this first stage is Block 4.

Not easy to use weblinks in Tapatalk.

Hope this works ok.

http://forum.nasaspaceflight.com/index.php?topic=42097.msg1694589#msg1694589

[russianhalo117]

Well as we've now seen it's a block 4 & not 3 which makes more sense to me as far as using the new fins is concerned.

Where have we seen that this first stage is Block 4? New grid fins doesn't mean it's a new Block.

Read the posts just up above my OP for the evidence.

They talk about the new grid fins, as far as I can tell (always helpful to quote relevant comments).

New grid fins do not imply that this first stage is Block 4.

Not easy to use weblinks in Tapatalk.

Star, just list the reply numbers for him so he can scroll up and look it up himself since you cant link..

[Confusador]

Well as we've now seen it's a block 4 & not 3 which makes more sense to me as far as using the new fins is concerned.

Where have we seen that this first stage is Block 4? New grid fins doesn't mean it's a new Block.

Read the posts just up above my OP for the evidence.

We have indicators that the *second* stage is block 4 (the raceways), and there are new gridfins.  I don't think we even know what indicators of a block 4 first stage would be. 

[Star One]

Well as we've now seen it's a block 4 & not 3 which makes more sense to me as far as using the new fins is concerned.

Where have we seen that this first stage is Block 4? New grid fins doesn't mean it's a new Block.

Read the posts just up above my OP for the evidence.

They talk about the new grid fins, as far as I can tell (always helpful to quote relevant comments).

New grid fins do not imply that this first stage is Block 4.

Not easy to use weblinks in Tapatalk.

Star, just list the reply numbers for him so he can scroll up and look it up himself since you cant link..

Thanks put a link now.

Boy is Tapatalk a nuisance sometimes!!!

[docmordrid]

Did a zoom/crop/adjustment to better see the horizontal and vertical grid fin cutouts. ISTM they should make for a bumpy leading edge profile.

[old_sellsword]

...I don't think we even know what indicators of a block 4 first stage would be.

Indeed, we have no idea what Block 4 S1 has in store.

Thanks put a link now.

Boy is Tapatalk a nuisance sometimes!!!

No worries! As Confusador pointed out, the upper stage is Block 4, but the first stage is still Block 3.

[Star One]

...I don't think we even know what indicators of a block 4 first stage would be.

Indeed, we have no idea what Block 4 S1 has in store.

Thanks put a link now.

Boy is Tapatalk a nuisance sometimes!!!

No worries! As Confusador pointed out, the upper stage is Block 4, but the first stage is still Block 3.

They are as bad as Apple for putting the model on things.

[russianhalo117]

Tweet Elon and SpaceX and see if its either confirmed or denied or if its and Block 3 mid evolution upgrade.

[FutureSpaceTourist]

On the S1 block 4 question, Gwynne was clear on the space show that block 4 is an intermediate step between 3 & 5 (i.e. has some but not all block 5 changes) and was due to fly soon. She also said it would take too long to explain all the differences.

So the issue reduces to whether SpaceX will introduce all the block 4 changes at once or more incrementally. I think SpaceX's MO is to do it step by step as soon as items (like titanium grid fins) are ready. However, there's the impact on FAA licensing to consider. There's no new licence for this launch (unless the FAA are slow to publish it) but I can believe that changing grid fin design, which only affects booster recovery, isn't a licensing issue and thus it wouldn't surprise me if this is a block 3 S1 with new grid fins.

[gongora]

It's not clear to me that block changes have any effect on the validity of the FAA license.  The previous flight-by-flight licensing may have been due to them being a newer launch provider with a little bit heavier oversight, and the large number of different orbits (they've gotten multi-flight licenses now for Iridium, CRS, GTO where additional flights shouldn't require all new analysis to be done.)

[intrepidpursuit]

We know the grid fins are put on at the launch site at the same time they are integrating the stages and can be omitted as well. That indicates that they are basically a standalone item, just as S2 is separate from S1. It is entirely plausible that they can put different grid fins on without making any other changes to the stage.

The grid fins do nothing either way to tell us the block number of the booster.

[old_sellsword]

We know the grid fins are put on at the launch site at the same time they are integrating the stages and can be omitted as well. That indicates that they are basically a standalone item, just as S2 is separate from S1. It is entirely plausible that they can put different grid fins on without making any other changes to the stage.

The grid fins do nothing either way to tell us the block number of the booster.

This is especially relevant considering they didn't even have to change the latch point for what was the bottom edge of the fin. You can see how they sacrificed the consistency of the pattern to keep that same location on the first stage.

[Ictogan]

It's not clear to me that block changes have any effect on the validity of the FAA license.  The previous flight-by-flight licensing may have been due to them being a newer launch provider with a little bit heavier oversight, and the large number of different orbits (they've gotten multi-flight licenses now for Iridium, CRS, GTO where additional flights shouldn't require all new analysis to be done.)

The Iridium licence is for "Falcon 9 version 1.2", not for any other version of F9.

[old_sellsword]

It's not clear to me that block changes have any effect on the validity of the FAA license.  The previous flight-by-flight licensing may have been due to them being a newer launch provider with a little bit heavier oversight, and the large number of different orbits (they've gotten multi-flight licenses now for Iridium, CRS, GTO where additional flights shouldn't require all new analysis to be done.)

The Iridium licence is for "Falcon 9 version 1.2", not for any other version of F9.

And Blocks 1, 2, 3, 4, and 5 all classify as "Falcon 9 version 1.2"

[edkyle99]

And Blocks 1, 2, 3, 4, and 5 all classify as "Falcon 9 version 1.2"

Not clear to me that this is true.

 - Ed Kyle

[edkyle99]

Here are same-angle comparisons of F9-30 and F9-38, the two Iridium Next launch vehicles.  Clear differences on Stage 2.

 - Ed Kyle

[JoerTex]

The music has started on the webcast.

[sevenperforce]

To the topic of re-entry profiles (from a few pages back)...

In situations where you have more than enough fuel for ASDS but not enough for a full RTLS, I don't think it would make any sense to do a "partial boostback" to kill horizontal velocity. The only reason for the immediate boostback is to decrease the amount of time you're headed downrange, saving boostback propellant. If they have extra prop, they'd save it for a longer entry burn. Oberth and all that.