Arianespace launch thread

[Kermann Nolandung]

8 hours ago, CBase said:

Scott Manley has a nice recap of the APU failure and why it was successful to show orbital capabilities while failing short on one important selling point

On his comment about the steep ascent that reaches 470 km, this is not the usual profile at 200-250 km, but we can notice the flight is not at its usual inclinaison.

For this part of flight I guess the launcher must keep communication with the ground. The video shows the coverage of the tracking stations.
After Kourou, the next one is Santa Maria of the Azores 4500 km away.
Coincidentally, the flight peaked at 470 km at mid distance and 470 km is the height above surface for a distance to horizon at 2500 km (a little more than half distance).
This is most likely the constraint imposing the 470 km peak.

[magnemoe]

On 5/25/2024 at 12:37 AM, tater said:

What makes Ariane 6 really tick (hint: it's the same special sauce as SLS/Orion):

Wait no common bulkhead on none of the stages? Thought any modern rockets had common bulkhead and only old designs used separated ones. 
Without it you need an interstage between them and an extra bulkhead. Yes you can use this space for stuff but you also has the interstage and engine bay. 

[darthgently]

3 hours ago, magnemoe said:

Wait no common bulkhead on none of the stages? Thought any modern rockets had common bulkhead and only old designs used separated ones. 
Without it you need an interstage between them and an extra bulkhead. Yes you can use this space for stuff but you also has the interstage and engine bay. 

Wouldn't the liquid hydrogen freeze the oxygen or something like that?

[Kermann Nolandung]

Ariane 5 used common bulkhead on its main stage.

Ariane 5 and 6 are heavy-lift launchers, heavy because  they were designed to be able to launch two payloads in GTO.
But the today's market is looking for more versatile missions, Ariane 5 is usually too heavy for a single payload.

Therefore in a redesign, the payload mass criteria can be loosened in an optimisation study.
A64 lifts more mass than A5 but less than the abandonned A5 ME with the Vinci engine

Separate tanks are easier, cheaper  than a single tank with a common bulkhead, at the expense of higher dry mass.
We can notice that the boosters are now attached to the intertank structure ; the LOX tank is no longer pulled but pushed by the boosters.
For the second stage, I guess they repeat the same industrial process (it is the same contractor) ; that leaves room for optimisation in the event of futur need.

[magnemoe]

10 hours ago, darthgently said:

Wouldn't the liquid hydrogen freeze the oxygen or something like that?

Looks like you are correct, many hydrolox rockets don't use common bulkheads. Still think an common bulkhead with isolation would be lighter. 

Edited July 13, 2024 by magnemoe

[tater]

Last Vega was apparently yesterday (tobe replaced with Vega C).

Didn't watch as Arianespace launch coverage is pretty tedious.

[tater]

Some fireworks testing:

 

[de Paor]

On 5/18/2023 at 9:27 PM, tater said:

The core stage dry mass is ~15t, Stage 2 is ~3.5t.

 

Where does Stage 2 = 3.5t come from.

This figure is not quoted anywhere else online or in literatrue.
Did you give an old number from Ariane 5 as a placeholder?

[tater]

8 hours ago, de Paor said:

Where does Stage 2 = 3.5t come from.

This figure is not quoted anywhere else online or in literatrue.
Did you give an old number from Ariane 5 as a placeholder?

Wow, 2 years ago... um dunno, lemme see if I can remember

[darthgently]

I’ve been wondering the same thing for two years.  I’m glad someone stepped forward to collect the receipts

Edited Tuesday at 11:47 PM by darthgently

[tater]

9 hours ago, de Paor said:

Did you give an old number from Ariane 5 as a placeholder?

Looking at the back and forth, exoscientist was using a 40t prop load and a 10% dry mass (4t). I found out the prop load was 31t, so I used 10% (including prop residuals) as dry mass, and slopped it up from 3.1 to 3.5 for the  engine mass (550 kg) and the PAM on top, plus unknowns.

But yeah, a guess since they don't publish that.

[tater]