Ariane 5 dual launch system

[AlphaKerman]

Why does other launch providers don't use dual launch system as Ariane rocket families do? I know that SpaceX had launch dual Boeing electric propulsion satellite, but it has to be the same type (unlike Arianespace SPELTRA and SYLDA system that basically had two payload room) and they had to find other satellite that agreed to be launched and use the same bus together. 

Edited November 16, 2016 by AlphaKerman

[Nibb31]

When designing a rocket, you typically design it for existing or planned payloads (notable exceptions are Falcon Heavy and SLS, which are both "rockets without a mission"). There is no point in building a rocket capable of sending 10 tons to GTO when most GTO comsats are in the 3 ton range.

Ariane 5 was originally designed to launch the Hermes shuttle. The shuttle was cancelled, but the payload mass requirements were maintained, so it ended up being too large and too expensive for commercial launches, which make up the bulk of its manifest. So they came up with the dual launch capacity as a way to overcome the launcher's market overcapacity.

This has a serious drawback in terms of flexibility. The payloads must both be targetted at a similar longitude (this is only used for GTO launches) and must follow the same launch schedule. If a payload from one customer is delayed, then the other customer is also delayed, which has a huge impact on revenue generated from the satellite. For those reasons, most customers prefer a single launch rather than dual launch, which is why Ariane 6 will be designed with a lighter 2 booster configuration for commercial launches and a 4 booster configuration for some rare heavier payloads.

Edited November 16, 2016 by Nibb31

[AlphaKerman]

18 minutes ago, Nibb31 said:

This has a serious drawback in terms of flexibility. The payloads must both be targetted at a similar longitude (this is only used for GTO launches) and must follow the same launch schedule. If a payload from one customer is delayed, then the other customer is also delayed, which has a huge impact on revenue generated from the satellite. 

Well, yeah i don't think about that. (Indeed that what happened to my country's satellite, PSN 6 has to be delayed as the other customer canceled their satellite). Thanks for your answer. 

But, i also forgot my other question. Does the system is patented (or something like that) so other can't use that system? Well, just imagine Falcon 9 already cheap flights cut into half by launching dual payload and also Proton - M and Atlas V

[Nibb31]

The actual dispenser might be patented, but I don't see that as an obstacle to dual-launching. As I said, it isn't really a market requirement, and launch providers adapt their offering to what their customers want to buy. It's more economical to design a smaller rocket for single payloads than to build a larger rocket for dual payloads that the market doesn't really want.

Falcon 9 doesn't have the payload capability to deliver two typical comsats. It already struggles delivering one.

[wumpus]

Launching multiple satellites to GTO sounds good enough, but there are only roughly 180 GTO slots up there, and only a portion of those are particularly valuable.  Convincing two of those slot owners to replace GTO birds at the same time is easier said than done.  Spacex has the issue that "increasing supply" (by launching cheaply) doesn't seem to increase actual launches, because even LEO satellites are so expensive.  GTO birds tend to be even worse (because of the 180 slot limitation), thus making individual launches make more sense (even if you could offer a "double barrel" launch).

[wumpus]

Am I the only one somewhat surprised that this is even an option?  I'd suspect they would be crowing about being able to launch even bigger (and better) birds into GTO.  Assuming that bandwidth is limited by power (and thus S/N)*, doubling the power of the bird (which I'd assume means at least doubling the number of solar panels and radiators, which should be a significant increase of mass) would allow an increase of bandwidth by ~70%.  While communications over GTO is pretty much "the cheap path" (and not preferred due to high latency), I'd still think that maximizing bandwidth would make sense.

* Pretty much all radios are constrained due to power output by regulation.  Not so satellites (they only overcome background noise within 1 degree of the bird), so all bets are off on what the real limit is (could be noise introduced by adding more power).

[Kryten]

4 hours ago, wumpus said:

Am I the only one somewhat surprised that this is even an option?  I'd suspect they would be crowing about being able to launch even bigger (and better) birds into GTO.  Assuming that bandwidth is limited by power (and thus S/N)*, doubling the power of the bird (which I'd assume means at least doubling the number of solar panels and radiators, which should be a significant increase of mass) would allow an increase of bandwidth by ~70%.  While communications over GTO is pretty much "the cheap path" (and not preferred due to high latency), I'd still think that maximizing bandwidth would make sense.

* Pretty much all radios are constrained due to power output by regulation.  Not so satellites (they only overcome background noise within 1 degree of the bird), so all bets are off on what the real limit is (could be noise introduced by adding more power).

The GTO communications market is pretty crowded and close to saturation already, you can't just put up twice-as-large (and twice as expensive) sat and expect it to get twice as many subscribers. You have to size for the market, and the market right now isn't too healthy.

[wumpus]

14 minutes ago, Kryten said:

The GTO communications market is pretty crowded and close to saturation already, you can't just put up twice-as-large (and twice as expensive) sat and expect it to get twice as many subscribers. You have to size for the market, and the market right now isn't too healthy.

While I wouldn't expect them to replace a satellite that still works, I'd at least assume the ability to add capacity if possible.  I suspect that the real reason is that you want a load that more than a single provider can put into space, although this is more a "make sure you can get into space (any one provider can be grounded for months at a time)" than "have a chance to negotiate" (although I'm sure the later helps).

[Kryten]

1 minute ago, wumpus said:

While I wouldn't expect them to replace a satellite that still works, I'd at least assume the ability to add capacity if possible.  I suspect that the real reason is that you want a load that more than a single provider can put into space, although this is more a "make sure you can get into space (any one provider can be grounded for months at a time)" than "have a chance to negotiate" (although I'm sure the later helps).

The largest sats have only been launchable by Ariane 5 for a while now, (e.g. the ~ 7 metric ton Terrestar-1 in 2009), so that can't be it.

[magnemoe]

15 hours ago, Kryten said:

The largest sats have only been launchable by Ariane 5 for a while now, (e.g. the ~ 7 metric ton Terrestar-1 in 2009), so that can't be it.

Still it has been an growth in comsat size over time, this is an added downside for Ariane 5 in that its harder to find two satellites who fit. 
Also the comsat size is determined by the launcher. 

[AlphaKerman]

On 11/17/2016 at 0:50 AM, wumpus said:

Launching multiple satellites to GTO sounds good enough, but there are only roughly 180 GTO slots up there

I'm not sure it's only had 180 slots available (some slots do have 2,3 or even 4 satellite though separated far enough to not disturb each other) 

Here list of active satellite recently: 

*ps: but i understand what you mean is that we had limited amount of slots 

 

But say only Ariane 5 use it's dual launch system, but i heard that some launch system had the capability to also launch two satellite at the time like Indian GSLV and even Russian Proton M, but i couldn't find the system to launch them. 

 

Btw, thanks for your explanation guys 

 

 

[Kryten]

The dual launches on Proton are small comsats that physically connect together, equivalent to the launches SpaceX have done. PSLV has a DLA similar to Ariana's SYLDRA except smaller, and H-2A does dual launches through an odd stacked fairing system;

Fairing on right stacks onto fairing at left.

[AlphaKerman]

Nice! 

 

Edited November 19, 2016 by AlphaKerman

[Phineas Freak]

Delta II also supports dual - manifested launches. ISEE and STEREO are some of the examples.

[magnemoe]

On 19.11.2016 at 1:39 AM, Kryten said:

The dual launches on Proton are small comsats that physically connect together, equivalent to the launches SpaceX have done. PSLV has a DLA similar to Ariana's SYLDRA except smaller, and H-2A does dual launches through an odd stacked fairing system;

Fairing on right stacks onto fairing at left.

This looks a lot like the Ariane system except they don' use an cover on the upper satellite. 
Wonder if this is more an protective cover on the upper satellite. This way you don't have to do the payload assembly in clean room. 
Cover would also hold the structure in bottom and the bottom part is metal as it has to support top satellite. 

Another way to protect the satellite is to put payload in fairing before putting it on the rocket. 

How do spacex handle the satellite flocks they have released a few times. 

[78stonewobble]

On ‎16‎-‎11‎-‎2016 at 2:09 PM, Nibb31 said:

When designing a rocket, you typically design it for existing or planned payloads (notable exceptions are Falcon Heavy and SLS, which are both "rockets without a mission"). There is no point in building a rocket capable of sending 10 tons to GTO when most GTO comsats are in the 3 ton range.

Ariane 5 was originally designed to launch the Hermes shuttle. The shuttle was cancelled, but the payload mass requirements were maintained, so it ended up being too large and too expensive for commercial launches, which make up the bulk of its manifest. So they came up with the dual launch capacity as a way to overcome the launcher's market overcapacity.

This has a serious drawback in terms of flexibility. The payloads must both be targetted at a similar longitude (this is only used for GTO launches) and must follow the same launch schedule. If a payload from one customer is delayed, then the other customer is also delayed, which has a huge impact on revenue generated from the satellite. For those reasons, most customers prefer a single launch rather than dual launch, which is why Ariane 6 will be designed with a lighter 2 booster configuration for commercial launches and a 4 booster configuration for some rare heavier payloads.

Wouldn't it be more fitting to say that the Falcon Heavy and SLS are rockets without a customer and/or market? They do have a "mission" / purpose... it's just noone has bought it yet...  

[wumpus]

7 hours ago, 78stonewobble said:

Wouldn't it be more fitting to say that the Falcon Heavy and SLS are rockets without a customer and/or market? They do have a "mission" / purpose... it's just noone has bought it yet...  

Elon Musk seems to be also pushing for an advanced "irridium-like" space communications network.  If you are building a constellation of ~4000 satellites (or even 400), then something like the Falcon Heavy (or better yet, the BFR) looks ideal.  These would pretty much require more birds per plane than such a rocket could lift.

[78stonewobble]

1 hour ago, wumpus said:

Elon Musk seems to be also pushing for an advanced "irridium-like" space communications network.  If you are building a constellation of ~4000 satellites (or even 400), then something like the Falcon Heavy (or better yet, the BFR) looks ideal.  These would pretty much require more birds per plane than such a rocket could lift.

I can't blame Elon Musk for wanting to sell the launch of 400 or 4000 satellites... I wonder who will be buying tho... Iridium went bankrupt tho?

[magnemoe]

4 hours ago, 78stonewobble said:

I can't blame Elon Musk for wanting to sell the launch of 400 or 4000 satellites... I wonder who will be buying tho... Iridium went bankrupt tho?

Iridium pushed phone not data and was to early, as I understand it went bankrupt and the US military bought it, not sure if they still own it. 

[Nibb31]

Iridium has been bought back and is about to launch their next generation constellation. In fact, it's scheduled to launch next month on Falcon 9.