Any reason for the longer burn? Special request by SES? Does it result in better data being collected (vs a 3 second burn)? If yes, why not make 5 second burns standard?
Quote from: hans_ober on 03/27/2017 06:06 pmAny reason for the longer burn? Special request by SES? Does it result in better data being collected (vs a 3 second burn)? If yes, why not make 5 second burns standard?I think I remember someone saying the 5 sec burn allows them to get a better checkout of the turbopumps.
Quote from: rockets4life97 on 03/27/2017 06:19 pmQuote from: hans_ober on 03/27/2017 06:06 pmAny reason for the longer burn? Special request by SES? Does it result in better data being collected (vs a 3 second burn)? If yes, why not make 5 second burns standard?I think I remember someone saying the 5 sec burn allows them to get a better checkout of the turbopumps. Which does kind of revalidate the question... why not do this for all? I honestly have no idea. Might be off topic for a mission specific thread. Maybe we need a "how long to static fire" thread! Or a poll. (KIDDING)
Quote from: Lar on 03/27/2017 06:33 pmQuote from: rockets4life97 on 03/27/2017 06:19 pmQuote from: hans_ober on 03/27/2017 06:06 pmAny reason for the longer burn? Special request by SES? Does it result in better data being collected (vs a 3 second burn)? If yes, why not make 5 second burns standard?I think I remember someone saying the 5 sec burn allows them to get a better checkout of the turbopumps. Which does kind of revalidate the question... why not do this for all? I honestly have no idea. Might be off topic for a mission specific thread. Maybe we need a "how long to static fire" thread! Or a poll. (KIDDING)As they've only done (to my memory) the prolonged static fire for the two SES missions to date, I'd place good money on it being a customer request.
Quote from: ChrisGebhardt on 03/27/2017 06:46 pmQuote from: Lar on 03/27/2017 06:33 pmQuote from: rockets4life97 on 03/27/2017 06:19 pmQuote from: hans_ober on 03/27/2017 06:06 pmAny reason for the longer burn? Special request by SES? Does it result in better data being collected (vs a 3 second burn)? If yes, why not make 5 second burns standard?I think I remember someone saying the 5 sec burn allows them to get a better checkout of the turbopumps. Which does kind of revalidate the question... why not do this for all? I honestly have no idea. Might be off topic for a mission specific thread. Maybe we need a "how long to static fire" thread! Or a poll. (KIDDING)As they've only done (to my memory) the prolonged static fire for the two SES missions to date, I'd place good money on it being a customer request.So whats the TEL umbilical damage like for A static fire? Does the longer burn do more damage?
I assume none as it never contacts the exhaust. It's only (?) as the stage climbs off the pad that the heat and exhaust impacts the tel and causes damage.Quote from: rsdavis9 on 03/27/2017 06:48 pmQuote from: ChrisGebhardt on 03/27/2017 06:46 pmQuote from: Lar on 03/27/2017 06:33 pmQuote from: rockets4life97 on 03/27/2017 06:19 pmQuote from: hans_ober on 03/27/2017 06:06 pmAny reason for the longer burn? Special request by SES? Does it result in better data being collected (vs a 3 second burn)? If yes, why not make 5 second burns standard?I think I remember someone saying the 5 sec burn allows them to get a better checkout of the turbopumps. Which does kind of revalidate the question... why not do this for all? I honestly have no idea. Might be off topic for a mission specific thread. Maybe we need a "how long to static fire" thread! Or a poll. (KIDDING)As they've only done (to my memory) the prolonged static fire for the two SES missions to date, I'd place good money on it being a customer request.So whats the TEL umbilical damage like for A static fire? Does the longer burn do more damage?
As they've only done (to my memory) the prolonged static fire for the two SES missions to date, I'd place good money on it being a customer request.
Quote from: ChrisGebhardt on 03/27/2017 06:46 pmAs they've only done (to my memory) the prolonged static fire for the two SES missions to date, I'd place good money on it being a customer request.If this static fire is meant to mimic the ignition and hold down of a real launch, does that mean they intend to hold the vehicle down for 5 seconds after ignition on the 30th as well? The downside is 2 seconds less prop at the end of a first stage burn but my guess is it lets them characterize the engine performance prior to hold-down release better once you get further away from start-up transients and they operate at steady state. Might be that's why this is a "customer request" because the customer is getting 2 seconds less margin (about 500 kg of fuel, right?)
Can someone double check my math?By my count, the current record for pad turnaround for launches on either LC39A/B is 17 days (STS- 51-D to STS-51-B, launched from LC39A). Not to start Go-fever or anything, but if SpaceX launches on Mar 30, thats 14 day turnaround. Sound correct?
No. Sequence on launch day will result in nominal release time at T0.
Quote from: ChrisGebhardt on 03/27/2017 08:01 pmNo. Sequence on launch day will result in nominal release time at T0.I would agree, clamps release at T-0, but would ignition sequence start earlier?It's a good question because I thought the "only" thing different between static hold-down fire pre-launch was that they didn't let go (I know that's oversimplified). Or is the static fire a modified sequence that only mimics the pad operations and fuel loading profile for the launch through to engine ignition, and not necessarily a mirror of the last 5 seconds prior to T-0?
How many seconds between ignition and T0?
Quote from: mn on 03/27/2017 09:30 pmHow many seconds between ignition and T0?See background here: https://www.google.com/search?q=Falcon+9+ignition+sequence
How many seconds between ignition and T0?Is this time consistent or has anyone noticed that number moving around on various launches?
