SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION

[notsorandom]

It is likely that this increase is coming now because of propellant densification? That is, they wish to keep the same T/W, but with more total fuel available?

That could be but they would see a benefit to their payload capacity even without increasing the amount of propellant. A higher T/W means less time fighting gravity. The Antares launch vehicle is swapping out its engines without a propellant increase and it is getting a better payload capacity. Because engine thrust is pretty tightly correlated with the expense of the engine and tanks and propellant are relatively cheap designers typically have optimized on getting the most out of a given amount of thrust rather then a given amount of propellant. So most rockets without optional add on boosters have a pretty low T/W. The Russians have a few that buck this trend for various reasons.

[2552]

Space News: SES Rethinking Being First To Fly a Full-throttle Falcon 9

“You know SpaceX is introducing into their manifest ... a modification of the current engine, with about a 20 percent increase in thrust," said Martin Halliwell, SES’s chief technical officer. "We’re making a decision internally as to whether we want to be the first to fly it.”

[Zardar]

According to Peter B. de Selding from SpaceNews:
"SES: We have decided to be inaugural customer for enhanced-version SpaceX Falcon 9 main engine, w/ our SES-9 aiming for Q2 launch."

Given CRS-6 in ~April, and CRS-7 in ~June, that would most likely put SES-9 in May?

[TrevorMonty]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines. They did this in beginning of 2014 with a 3D printed part fitted to one of the engines. One of the many bonuses of having multiple engines.

[Zardar]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines. They did this in beginning of 2014 with a 3D printed part fitted to one of the engines. One of the many bonuses of having multiple engines.

Its possible the "upgraded" engine may have flown, but this will be the first time it will have flown with the increased thrust.

And even "upgraded" may be a misnomer, since they may well be the same engines, just qualified for the higher output, along with perhaps control software upgrades and changes to propellant flow/ratios etc.

[FutureSpaceTourist]

According to Peter B. de Selding from SpaceNews:
"SES: We have decided to be inaugural customer for enhanced-version SpaceX Falcon 9 main engine, w/ our SES-9 aiming for Q2 launch."

Given SES' previously stated uncertainty about being the inaugural customer, I think it's interesting why they decided to do it (besides, obviously, being confident in data from SpaceX about any risks). I wonder if Peter B. de Selding's other tweet gives a clue:

SES: What a difference 1 sat makes: If SpaceX launches SES-9 in Q2, 2015-2017 CAGR is 5%. If in Q3, CAGR is 3.5%. Co has 54-sat fleet.

[eweilow]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines. They did this in beginning of 2014 with a 3D printed part fitted to one of the engines. One of the many bonuses of having multiple engines.

Its possible the "upgraded" engine may have flown, but this will be the first time it will have flown with the increased thrust.

And even "upgraded" may be a misnomer, since they may well be the same engines, just qualified for the higher output, along with perhaps control software upgrades and changes to propellant flow/ratios etc.

It will especially be the first time it flies with all nine engines having higher thrust figures.

[Antares]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines.

Wrong

[Robotbeat]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines.

Wrong

Actually, right. They flew a Merlin that had a 3D printed LOx valve on one of their previous flights.

[TrueBlueWitt]

Space News: SES Rethinking Being First To Fly a Full-throttle Falcon 9

“You know SpaceX is introducing into their manifest ... a modification of the current engine, with about a 20 percent increase in thrust," said Martin Halliwell, SES’s chief technical officer. "We’re making a decision internally as to whether we want to be the first to fly it.”

120%? That's 175klb. I don't think we've seen anything over 112% before for the upgrade have we?  This is along with densification would allow enough margin for boost back even with com SATs? How they get to 53t Without cross feed for FH?

[Antares]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines.

Wrong

Actually, right. They flew a Merlin that had a 3D printed LOx valve on one of their previous flights.

Sigh.  I deleted the part about the DMLS valve.  He said he doubts it's the first flight of the engine.  I said wrong.

[Dudely]

Agreed, there is no way for them to test this without doing it to all engines at once. That goes for propellent densification as well as increased thrust.

[LouScheffer]

According to Peter B. de Selding from SpaceNews:
"SES: We have decided to be inaugural customer for enhanced-version SpaceX Falcon 9 main engine, w/ our SES-9 aiming for Q2 launch."

Given SES' previously stated uncertainty about being the inaugural customer, I think it's interesting why they decided to do it (besides, obviously, being confident in data from SpaceX about any risks). I wonder if Peter B. de Selding's other tweet gives a clue:

SES: What a difference 1 sat makes: If SpaceX launches SES-9 in Q2, 2015-2017 CAGR is 5%. If in Q3, CAGR is 3.5%. Co has 54-sat fleet.

Here's my thinking on their thinking, obviously guessing.

From the second SES quote above, a Q2 launch helps their bottom line.  So request a Q2 launch on the old F9, or the enhanced?  Assuming no more fuel, improved thrust helps only gravity losses + a tiny boost to ISP.  Gravity losses are typically 1-1.5 km/sec.  The exact calculations are complex (more power helps a lot at takeoff, but not at all when acceleration limited, drag values go up, etc.) Make a wild guess and say losses are reduced by 10%, or 150 m/s or so.  That gives them 150 m/s more for GTO injection, which translates (not 1:1, but not too far different) to 150 m/s less needed by the satellite.  Since GEO stationkeeping is around 50 m/s per year, that's 3 years of extra life.

So I think that's the gamble - 3 years of extra life vs. extra risk of exploding on the pad.  So which way to bet?   If the satellite lasts for 15 years, then the expected years of life lost is failure probability x 15. So if there's less than a 20% chance of blowing up, go for the extra life.  SpaceX must have convinced them the odds of failure are less than 20%. 

[Eerie]

Agreed, there is no way for them to test this without doing it to all engines at once. That goes for propellent densification as well as increased thrust.

Hmm...

Why not put a new engine in the middle position and run it with increased thrust?

[Barrie]

I was wondering if the recent extra-loud test at McGregor might have been something to do with convincing SES the uprating is safe.

[Zardar]

Here's my thinking on their thinking, obviously guessing.

That gives them 150 m/s more for GTO injection, which translates (not 1:1, but not too far different) to 150 m/s less needed by the satellite.  Since GEO stationkeeping is around 50 m/s per year, that's 3 years of extra life.

Also, with the electric thruster used for apogee-raising on the sat, it takes 4-6 months to raise the sat to GSO.
If a more powerful F9 can lift it higher, not only will it save sat lifetime, it can get into a position to start earning revenue several months sooner. That will pull future revenue into 2015, making the beancounters very happy when it comes to preparing the annual accounts.

[Robotbeat]

I doubt this is first flight of this engine, they have been testing modified engines by flying 1 in F9 along with 8 standard/proven engines.

Wrong

Actually, right. They flew a Merlin that had a 3D printed LOx valve on one of their previous flights.

Sigh.  I deleted the part about the DMLS valve.  He said he doubts it's the first flight of the engine.  I said wrong.

But this is the Internet, so anything you say (or that people think you say) will be picked apart for the most inconsequential, cosmetic flaw.

[TrevorMonty]

Agreed, there is no way for them to test this without doing it to all engines at once. That goes for propellent densification as well as increased thrust.

Hmm...

Why not put a new engine in the middle position and run it with increased thrust?

They can run one at max power and throttle back the ones around it.

[MTom]

According to Peter B. de Selding from SpaceNews:
"SES: We have decided to be inaugural customer for enhanced-version SpaceX Falcon 9 main engine, w/ our SES-9 aiming for Q2 launch."

Given SES' previously stated uncertainty about being the inaugural customer, I think it's interesting why they decided to do it (besides, obviously, being confident in data from SpaceX about any risks). I wonder if Peter B. de Selding's other tweet gives a clue:

I wouldn't be surprised if this was part of a dealing for some discount of the launch price too.

[woods170]

And the full write-up on the SES decision to fly first on the uprated F9

http://spacenews.com/ses-decides-to-take-the-plunge-on-enhanced-falcon-9/