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

[dante2308]

Just a quick question about viewing this launch since I happen to be in Pasadena. Does anyone in area know the best bet for a good viewing around this area or is it best to trek out to the coast?

[russianhalo117]

Just a quick question about viewing this launch since I happen to be in Pasadena. Does anyone in area know the best bet for a good viewing around this area or is it best to trek out to the coast?

Answers can be found in the pinned SpaceX Falcon 9 - Vandenberg - Launch Viewing Thread (http://forum.nasaspaceflight.com/index.php?topic=41995.0).

[old_sellsword]

And the difference between the raceways signifies what changes between Block 3 and Block 4?

From what we can physically see, yes. NROL-76 also performed a successful long coast test after payload separation, and both flights thus far have used the faster LOX loading procedure.

[sevenperforce]

And the difference between the raceways signifies what changes between Block 3 and Block 4?

From what we can physically see, yes. NROL-76 also performed a successful long coast test after payload separation, and both flights thus far have used the faster LOX loading procedure.

So the different raceways are associated with a different internal flow/coolant/pressurant configuration to enable faster LOX load times and some different coasting/persistence capabilities?

Does anyone outside of SX know what the different configuration is?

[intrepidpursuit]

And the difference between the raceways signifies what changes between Block 3 and Block 4?

From what we can physically see, yes. NROL-76 also performed a successful long coast test after payload separation, and both flights thus far have used the faster LOX loading procedure.

So the different raceways are associated with a different internal flow/coolant/pressurant configuration to enable faster LOX load times and some different coasting/persistence capabilities?

Does anyone outside of SX know what the different configuration is?

Raceway visibility isn't directly related to any of the other block 4 changes as far as we know, they just indicate block 4. I haven't seen any info on what the changes are other than generally better performance, faster loading, and theories on how those might be related.

[Jim]

And the difference between the raceways signifies what changes between Block 3 and Block 4?

From what we can physically see, yes. NROL-76 also performed a successful long coast test after payload separation, and both flights thus far have used the faster LOX loading procedure.

So the different raceways are associated with a different internal flow/coolant/pressurant configuration to enable faster LOX load times and some different coasting/persistence capabilities?

Does anyone outside of SX know what the different configuration is?

Unrelated to LOX load times

[old_sellsword]

And the difference between the raceways signifies what changes between Block 3 and Block 4?

From what we can physically see, yes. NROL-76 also performed a successful long coast test after payload separation, and both flights thus far have used the faster LOX loading procedure.

So the different raceways are associated with a different internal flow/coolant/pressurant configuration to enable faster LOX load times and some different coasting/persistence capabilities?

Does anyone outside of SX know what the different configuration is?

Unrelated to LOX load times

Would you be able to elaborate on what the raceway changes are related to?

[Skylab]

You know the launch business has changed when an article mentions "a previously-unflown first stage".

[Scylla]

What is the purpose of the spiky bits?

[docmordrid]

What is the purpose of the spiky bits?

ISTM they serve a similar function as the tubercles on the flipper of a humpback whale: flow control. It should cause different parts of the fin to see transonic flow at different times.

[punder]

What is the purpose of the spiky bits?

I would guess they are just cutaways where metal isn't needed for strength. Like lightening holes in a wing rib.

[russianhalo117]

What is the purpose of the spiky bits?

Transonic flow/shock/sound reduction is the reason its used on latest generation aircraft (primarily engines but it testing for leading edges et cetera) but probably serves a different purpose on this rocket.

https://www.nasaspaceflight.com/2017/06/spacex-falcon-9-iridium-next-2-launch/

The larger size of the fins, along with other improvements to their aerodynamics, increase the force they can apply to control the rocket’s course and improve the amount of lift they provide relative to drag. This improves the gliding ability of the booster, reducing the amount of fuel that needs to be reserved for bringing the core home. The new fins will also aid Falcon Heavy’s side boosters for their return.

[matthewkantar]

Wow. At first I thought the design had changed very little. Was I ever wrong! Looks much more aero.

Matthew

[Scylla]

Fins have a much more complex curved surface than old fins. Might that be to improve transonic flow?

[punder]

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

[Jarnis]

They basically look... Grid Fin Claws! 

[AC in NC]

They basically look... Grid Fin Claws! 

[Star One]

The grid fins are dark. So no more protective coating. Must really be the new ones.

Seems unlike as I thought these were part of block 5 upgrades.

They're not going to just fly a rocket with 50 new things someday. A lot of block 5 stuff will probably be rolled into earlier models. Things like the new grid fins will need some software tweaking and maybe a few mods and they might want the official first block 5 to have all that in it's final form.

But it seems unlikely they would put them on this as I thought this was a block 3. Surely if you wanted to phase stuff in you'd start with the block 4.

This first stage is both Block 3 and debuting the new grid fins.

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.

[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.

[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.