SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION

[Oersted]

Given how good a job BO did of releasing a very slick video after their NS landing

SpaceX showed their landing LIVE, as everyone experienced it. Maybe they learned their lesson, maybe partly as a result of BOs success, but they didn't hide it. I'll take an organic, live video like this over a slick promo anytime.

Absolutely spot on!

[Lars-J]

Given how good a job BO did of releasing a very slick video after their NS landing

SpaceX showed their landing LIVE, as everyone experienced it. Maybe they learned their lesson, maybe partly as a result of BOs success, but they didn't hide it. I'll take an organic, live video like this over a slick promo anytime.

Absolutely spot on!

And I'm sure they will be releasing a slick video within days as well. 

[gadgetmind]

And I'm sure they will be releasing a slick video within days as well. 

I hope so 'cos I'm greedy and want both the live kicks and the "director's cut with extra unseen footage" to keep playing over and over.

[kirghizstan]

Given how good a job BO did of releasing a very slick video after their NS landing

SpaceX showed their landing LIVE, as everyone experienced it. Maybe they learned their lesson, maybe partly as a result of BOs success, but they didn't hide it. I'll take an organic, live video like this over a slick promo anytime.

Absolutely spot on!

And I'm sure they will be releasing a slick video within days as well. 

I'm not bashing BO here, but their video mixed in CGI so it overhyped their achievement

[corrodedNut]

I think the double sonic boom right after touchdown is the best. Every vehicle has it's quirks and personality (I know, shuttle did it too, but way before "wheel stop"), I have a feeling this will become well known as Falcon 9's "calling card"...BUH-BANG...the Falcon has landed! Can't wait for the Falcon Heavy quadruple report.

[ugordan]

I think the double sonic boom right after touchdown is the best.

What intrigued me was that pretty much all amateur videos out there I saw heard a triple sonic boom.

[gregpet]

I think the double sonic boom right after touchdown is the best. Every vehicle has it's quirks and personality (I know, shuttle did it too, but way before "wheel stop"), I have a feeling this will become well known as Falcon 9's "calling card"...BUH-BANG...the Falcon has landed! Can't wait for the Falcon Heavy quadruple report.

How far inland could the sonic boom be heard?

Assuming regular reuse, is there any chance this could become a nuisance (and therefore political issue)?  Didn't the the Concorde have to adjust their routes and destinations (which created inefficiencies) given its sonic boom.

I have never heard a sonic boom so no idea what its effects could be on a community (especially the community that doesn't care about the coolness of this achievement!)

[daveglo]

How far inland could the sonic boom be heard?

Sonic boom projections included in the EIS report for LZ-1, located here: http://www.patrick.af.mil/shared/media/document/AFD-141107-004.pdf

Page 88.

[EchozAurora]

I haven't yet seen anything about where the sonic boom was reported (though I did observe the projections), but as sonic booms were common with the space shuttle I wouldn't expect it to be a major political issue in this area.  I was there to hear it (out at Jetty Park just south of Cape Canaveral AFB so pretty close) and while loud it wasn't exceptionally so.  I would compare it to fireworks... sharp and brief.

[woods170]

And Arianespace workers don't worry because they are quasi-government -- same reason NASA workers don't worry.

You might want to reconsider that line. Arianespace workers are not quasi-government, they are company employees who can be hired, fired and laid off just like any other commercial employee. NASA civil servants aren't guaranteed a job for life, and NASA contractors definitely get nervous around contract expiration time.

sorry, but do you know what it takes for a company to fire an employee in France?      I concede your other points.

Emphasis mine. In fact it does not take all that much. One of my two daytime jobs is working for a French company. During the economic crisis (2009 - 2013) it fired boatloads of employees in France easily. All it takes is to have some evidence showing that the targeted employees are surplus or endanger the economic welfare of the company. That's it.

[woods170]

I think the double sonic boom right after touchdown is the best.

What intrigued me was that pretty much all amateur videos out there I saw heard a triple sonic boom.

Leading end, grid fins, trailing end.

[meekGee]

I'm going to slay this dragon...

SpaceX doesn't need 69 good launches in order to be "as reliable" as Ariane 5.  (or Atlas V, or Delta IV)

This is because SpaceX has access now to its first stages post flight.

Even if each stage will never fly again, you already have the ability to look for marginal design areas - and that's worth tens and tens of empirical flights.

69 is not a huge statistical number.  There can still be components on these rockets that are marginally designed, and nobody knows it.  SpaceX right now can deconstruct the stage, and test each and every component to failure, to see how close it really got.  This is HUGE in terms of validating the design.

Then, once the stages re-fly, then you also get on top of QA issues.  F9 failed because of a badly manufactured strut.  STS-133 almost did the same.  Proton failed because of a badly assembled accelerometer.  When stages begin to re-fly, you now validate each vehicle, not only the design in general.

So give them 1-2 years, and the 69-flight record will become meaningless.

The European launcher does have an edge in reliability that will take some time to beat, if SpaceX can beat it. 69 successes in a row is reassuring when you want to put an 8 or 9 billion dollar telescope in orbit.

Matthew

Ariane 5 had SEVERAL major failures in its first flights. Falcon 9 has had 1 out of 20. SpaceX will beat it in time.

I am familiar with Ariane's teething problems. If Spacex is flawless from here out, it will still be several years before they have 69 successes in a row. The tension between constant innovation and reliability is real.

Matthew

[notsorandom]

I think the double sonic boom right after touchdown is the best. Every vehicle has it's quirks and personality (I know, shuttle did it too, but way before "wheel stop"), I have a feeling this will become well known as Falcon 9's "calling card"...BUH-BANG...the Falcon has landed! Can't wait for the Falcon Heavy quadruple report.

Many including Mr. Musk have said they heard the boom and though the stage crashed and blew up. That is pretty good comedic timing. Had there been a few moments to think about this they would have figured out that if the stage crashed there would be a very noticeable delay in hearing the explosion. It just goes to show both how quickly these things go and how exciting they are that people who understand the sound delay didn't process it.

[ugordan]

What intrigued me was that pretty much all amateur videos out there I saw heard a triple sonic boom.

Leading end, grid fins, trailing end.

Perhaps, but there's roughly a 190 ms delay between the 1st and 2nd boom and around 100 ms between the 2nd and the 3rd in this video: www.youtube.com/watch?v=B5pTDx-hFDc . Yet the fins are vastly closer to the tail end than the engines.

[leetdan]

The shuttle booms could be heard 100+ miles away, depending on the entry path I could hear these growing up in South Florida.  On Monday night we heard 3, about 8 miles from the pad on SR-3 just outside the KSC gates.

[Craftyatom]

What intrigued me was that pretty much all amateur videos out there I saw heard a triple sonic boom.

Leading end, grid fins, trailing end.

Perhaps, but there's roughly a 190 ms delay between the 1st and 2nd boom and around 100 ms between the 2nd and the 3rd in this video: . Yet the fins are vastly closer to the tail end than the engines.

There really isn't much else on the stage to cause that boom, though - the front of the stage should always generate a boom, and the tail end should always generate a boom, so unless the exhaust plume formed its own bow wave ~200ft below the engines, the only third culprit is the fins.

Regarding why the timing difference is 1:2 rather than 1:6 or 1:9 (based on eyeballing), it could just be that the booms don't carry through the atmosphere linearly - I'm no aerodynamics expert, but depending on the angle you hear it from and the distance it travels, there may well be some big differences in arrival time.

I suppose the next experiment would be to compare these timings with the timings from the shuttle, along with the relative lengths of the vehicles.

[TomH]

The shuttle booms could be heard 100+ miles away, depending on the entry path I could hear these growing up in South Florida.  On Monday night we heard 3, about 8 miles from the pad on SR-3 just outside the KSC gates.

The shuttle came in over populated land traveling west to east while performing a series of S turns. A RTLS stage is traveling east to west over the Atlantic Ocean and barely reaches the coastline of a barrier island at the very last moment. The two events are not equivocal. Now a BFR launched at Brownsville that passes over FL and lands at the cape.......that would be a different story.

[ArbitraryConstant]

from the audio track of the linked video

[cscott]

What intrigued me was that pretty much all amateur videos out there I saw heard a triple sonic boom.

Leading end, grid fins, trailing end.

Perhaps, but there's roughly a 190 ms delay between the 1st and 2nd boom and around 100 ms between the 2nd and the 3rd in this video: . Yet the fins are vastly closer to the tail end than the engines.

There really isn't much else on the stage to cause that boom, though - the front of the stage should always generate a boom, and the tail end should always generate a boom, so unless the exhaust plume formed its own bow wave ~200ft below the engines, the only third culprit is the fins.

Regarding why the timing difference is 1:2 rather than 1:6 or 1:9 (based on eyeballing), it could just be that the booms don't carry through the atmosphere linearly - I'm no aerodynamics expert, but depending on the angle you hear it from and the distance it travels, there may well be some big differences in arrival time.

I suppose the next experiment would be to compare these timings with the timings from the shuttle, along with the relative lengths of the vehicles.

The grid fins stick out from the core, which would push the virtual tip of their shock cone toward the nose.

[Targeteer]

I couldn't find this earlier in the thread although it may be in another thread...