SpaceX F9 : Starlink v1.0 L8 Rideshare : June 13, 2020

[Norm38]

A static fire also adds a thermal cycle to the booster, with all the flexing and stresses that entails.  That may not matter much for an expendable booster, but for a reusable booster, that effectively doubles the thermal cycling.  10 launches equals 20 cycles.  I'd rather it be 10 cycles for 10 launches.
They may be reaching the point where static fires do more harm than good.

[FutureSpaceTourist]

https://twitter.com/spacexfleet/status/1270883267290554374

"Of Course I Still Love You" droneship has arrived at the landing zone for the Starlink mission - NET June 12th.

The droneship is ~629 km downrange.

[CorvusCorax]

A static fire also adds a thermal cycle to the booster, with all the flexing and stresses that entails.  That may not matter much for an expendable booster, but for a reusable booster, that effectively doubles the thermal cycling.  10 launches equals 20 cycles.  I'd rather it be 10 cycles for 10 launches.
They may be reaching the point where static fires do more harm than good.

That might be even more critical for the engines.
Even jet engines have a limited cycle count before overhaul, because temperature and load cycling eventually leads to fatigue cracks in the turbine blades. That must be much worse for the merlin's turbopumps, dealing with cryogenic temperatures and more severe loads.

Granted, the cycle load is uneven. While for 6 of the 9 engines that only burn in the boost phase, the static fire doubles the cycle load , for the remaining 3 engines - especially the center one, the static fire cycle is almost benign - compared to the horror trip of launch, boost-back, entry and landing - all in rapid succession.

[Ken the Bin]

Per this NGA NOTMAR, the launch is pushed back from the 12th to the 13th, with a new backup day of the 14th:

110221Z JUN 20
NAVAREA IV 499/20(11,26).
WESTERN NORTH ATLANTIC.
FLORIDA.
1. HAZARDOUS OPERATIONS, ROCKET LAUNCHING
   130846Z TO 131044Z JUN, ALTERNATE 140824Z TO
   141022Z JUN IN AREAS BOUND BY:
   A. 28-37-00N 080-36-05W, 28-50-00N 080-24-00W,
      29-12-00N 079-56-00W, 29-11-00N 079-53-00W,
      28-36-00N 080-24-00W, 28-30-06N 080-32-51W,
      28-31-46N 080-33-39W.
   B. 32-02-00N 077-02-00W, 33-09-00N 075-58-00W,
      33-23-00N 075-36-00W, 33-23-00N 074-56-00W,
      33-15-00N 074-37-00W, 32-48-00N 074-35-00W,
      32-29-00N 074-59-00W, 31-40-00N 076-42-00W.
2. CANCEL NAVAREA IV 484/20.
3. CANCEL THIS MSG 141122Z JUN 20.

[blach]

Granted, the cycle load is uneven. While for 6 of the 9 engines that only burn in the boost phase, the static fire doubles the cycle load , for the remaining 3 engines - especially the center one, the static fire cycle is almost benign - compared to the horror trip of launch, boost-back, entry and landing - all in rapid succession.

Actually, given that they use three engines for entry burn, I'd assume those were three outer engines. Landing is then done with the center engine. If they're also doing boost-back (it's been a bit) I assume they do that with 3 engines that aren't involved in the other two burns leaving just 2 engines that haven't done a landing-related burn. Merlins can also be removed afaik as well, so they could rotate the engines if needed.

[AndrewRG10]

Granted, the cycle load is uneven. While for 6 of the 9 engines that only burn in the boost phase, the static fire doubles the cycle load , for the remaining 3 engines - especially the center one, the static fire cycle is almost benign - compared to the horror trip of launch, boost-back, entry and landing - all in rapid succession.

Actually, given that they use three engines for entry burn, I'd assume those were three outer engines. Landing is then done with the center engine. If they're also doing boost-back (it's been a bit) I assume they do that with 3 engines that aren't involved in the other two burns leaving just 2 engines that haven't done a landing-related burn. Merlins can also be removed afaik as well, so they could rotate the engines if needed.

Landing is only ever done with only centre engine on RTLS F9 flights. There's several types of landing, there's the 16 second, 20 second, 24 second and 30. All except the 30 second burn uses three engines at some point

[blach]

Granted, the cycle load is uneven. While for 6 of the 9 engines that only burn in the boost phase, the static fire doubles the cycle load , for the remaining 3 engines - especially the center one, the static fire cycle is almost benign - compared to the horror trip of launch, boost-back, entry and landing - all in rapid succession.

Actually, given that they use three engines for entry burn, I'd assume those were three outer engines. Landing is then done with the center engine. If they're also doing boost-back (it's been a bit) I assume they do that with 3 engines that aren't involved in the other two burns leaving just 2 engines that haven't done a landing-related burn. Merlins can also be removed afaik as well, so they could rotate the engines if needed.

Landing is only ever done with only centre engine on RTLS F9 flights. There's several types of landing, there's the 16 second, 20 second, 24 second and 30. All except the 30 second burn uses three engines at some point

I don't think this is true, or maybe we're talking about different things. Here's a bit from the November Starlink mission where they explicitly state that the landing burn is a single engine burn:

Same from the most recent mission:

[AndrewRG10]

Granted, the cycle load is uneven. While for 6 of the 9 engines that only burn in the boost phase, the static fire doubles the cycle load , for the remaining 3 engines - especially the center one, the static fire cycle is almost benign - compared to the horror trip of launch, boost-back, entry and landing - all in rapid succession.

Actually, given that they use three engines for entry burn, I'd assume those were three outer engines. Landing is then done with the center engine. If they're also doing boost-back (it's been a bit) I assume they do that with 3 engines that aren't involved in the other two burns leaving just 2 engines that haven't done a landing-related burn. Merlins can also be removed afaik as well, so they could rotate the engines if needed.

Landing is only ever done with only centre engine on RTLS F9 flights. There's several types of landing, there's the 16 second, 20 second, 24 second and 30. All except the 30 second burn uses three engines at some point

I don't think this is true, or maybe we're talking about different things. Here's a bit from the November Starlink mission where they explicitly state that the landing burn is a single engine burn: ...

Same from the most recent mission: ...

I'm thinking of landing like you, it's a fact that the 16 second and 20 second landing burns use 3 engines, 24 second used soley on Starlink flights except the most recent one might use 1 engine but I'm just stating the facts I know.
Here's a 20 second landing burn.


If you want to discuss this more, not this thread, talk to me elsewhere.

[Vettedrmr]

Actually, given that they use three engines for entry burn, I'd assume those were three outer engines. Landing is then done with the center engine. If they're also doing boost-back (it's been a bit) I assume they do that with 3 engines that aren't involved in the other two burns leaving just 2 engines that haven't done a landing-related burn. Merlins can also be removed afaik as well, so they could rotate the engines if needed.

First, welcome to the forum!!  So much quality on this site, I learn something just about every time I visit.

Second, there's a lot of info to be had, but short version is: there are only 3 engines on a 1st stage that have the capability of restarting.  Those 3 engines are used for the entry burn, the center engine for the landing burn.  Boostback burns I assume are 3 engine burns, but I'm honestly not sure.

Third, look into subscribing into the L2 section.  Lots of stuff in there that's a lot of fun to dig into, and it helps NSF fund this site.

Have a good one,
Mike

[FutureSpaceTourist]

L-2 launch weather forecast for Saturday, now 70% GO

[FutureSpaceTourist]

twitter.com/spacex/status/1271116917420388352

Targeting Saturday, June 13 at 5:21 a.m. EDT for launch of 58 Starlink satellites and 3 @planetlabs spacecraft – the first SpaceX SmallSat Rideshare Program launch

https://twitter.com/spacex/status/1271116918871609344

The booster supporting this mission previously launched Dragon’s 19th and 20th resupply missions to the @space_station

[FutureSpaceTourist]

https://twitter.com/planetlabs/status/1271125796313280512

Launch day is nearly here for SkySats 16-18! The sats will be hitching a ride on @SpaceX's Falcon 9 on June 13 - their 1st Starlink Rideshare Program launch. Check out our blog for info on these SkySats and how they’ll compliment our 15 already in orbit. go.planet.com/spacexskysatla…

[Zpoxy]

Granted, the cycle load is uneven. While for 6 of the 9 engines that only burn in the boost phase, the static fire doubles the cycle load , for the remaining 3 engines - especially the center one, the static fire cycle is almost benign - compared to the horror trip of launch, boost-back, entry and landing - all in rapid succession.

Actually, given that they use three engines for entry burn, I'd assume those were three outer engines. Landing is then done with the center engine. If they're also doing boost-back (it's been a bit) I assume they do that with 3 engines that aren't involved in the other two burns leaving just 2 engines that haven't done a landing-related burn. Merlins can also be removed afaik as well, so they could rotate the engines if needed.

The three engine burns utilize the center engine, and two outer engines, always the same two outer engines, forming three in a row. Those are the only engines plumbed with the inflight TEA-TEB starting fluid, no choice.
 

[karanfildavut]

Based on the fact that they actually removed two Starlinks for the planet satellites even with all the space in the fairing, is it safe to say that starlink launches are fundamentally mass limited and that any rideshare will end up in a reduction of starlink count for that launch? I can see see SpaceX charging by the starlink-equivalent for such a case.

[ZachS09]

Given that the Starlink sats each weigh 260 kg, and each SkySat weighs 110 kg, the total payload mass is 15,410 kg not including the SkySat dispensers.

https://directory.eoportal.org/web/eoportal/satellite-missions/s/skysat

[cppetrie]

Based on the fact that they actually removed two Starlinks for the planet satellites even with all the space in the fairing, is it safe to say that starlink launches are fundamentally mass limited and that any rideshare will end up in a reduction of starlink count for that launch? I can see see SpaceX charging by the starlink-equivalent for such a case.

I’m virtually certain somewhere up thread it was said that this is a full batch of 60 Starlink sats plus the 3 ride share sats.

Edit: nevermind - the tweet says 58.....missed that when reading it. Seems reasonable in that case that the cost of launch is maybe 50% above the share of the launch cost for those two Starlink sats. The extra going towards integration plus some profit. Internal
Launch cost of $15 million so $500k for those two sats. Launch probably cost the ride share about $750k, perhaps a million. That’s a pretty good deal I’d think.

[ajmarco]

Based on the fact that they actually removed two Starlinks for the planet satellites even with all the space in the fairing, is it safe to say that starlink launches are fundamentally mass limited and that any rideshare will end up in a reduction of starlink count for that launch? I can see see SpaceX charging by the starlink-equivalent for such a case.

I don't think that the removal of 2 starlink satellites was due to mass limitations. Looking at the image of all the satellites in the faring it looks like that the adapter that was designed by Planet takes the place of those 2 starlinks (1 layer of satellites) so that the entire stack is still held in place by the tension rods that are used on a standard starlink launch.

[gongora]

https://twitter.com/TSKelso/status/1271245673879355392

CelesTrak has generated SupTLEs for the #Starlink-9 launch attempt set for Jun 13 at 0921 UTC. This launch will include 58 Starlink & 3 SkySat satellites. Deployment is set for Jun 13 at 09:47:23.210 UTC.

Expected deployment this time will be later in the mission and should occur over Southern Europe.

[Thunderscreech]

Launch TFR is up. 

https://twitter.com/SpaceTfrs/status/1271226973516296192

[Tomness]

Based on the fact that they actually removed two Starlinks for the planet satellites even with all the space in the fairing, is it safe to say that starlink launches are fundamentally mass limited and that any rideshare will end up in a reduction of starlink count for that launch? I can see see SpaceX charging by the starlink-equivalent for such a case.

I don't think that the removal of 2 starlink satellites was due to mass limitations. Looking at the image of all the satellites in the faring it looks like that the adapter that was designed by Planet takes the place of those 2 starlinks (1 layer of satellites) so that the entire stack is still held in place by the tension rods that are used on a standard starlink launch.

Elon said they could do more but at the cost  of recovery. So this does show they could pack more. I want to see a FH with extented fairing hopefully with 100 to 120 Starlink launch before precursor to Starship.