Author Topic: Falcon 9 First Stage booster controlled-descent test video (ORBCOMM OG2 mission)  (Read 62150 times)

Offline Llian Rhydderch

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SpaceX has released chase-plane video of the booster controlled-descent test on the recent ORBCOMM OG2 flight, filmed on 14 July 2014.




Edit:  clarified that this is chase plane video.  The initial video released last month, with the on-board rocket cam views, is .
« Last Edit: 08/14/2014 10:05 pm by Llian Rhydderch »
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Offline moralec

Finally! What an amazing video!

Edit: Added some captures....
« Last Edit: 08/14/2014 10:00 pm by moralec »

Offline Maciej Olesinski

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Touchdown is really nice and smooth. It looks like first stage is taking its time.
I wonder if there is much more of the video that we will never see.

Edit: isn't whole stage black thanks to residues from engine burn?
Edit2: ok now I've finally see the 4x slow motion
« Last Edit: 08/14/2014 09:40 pm by Maciej Olesinski »

Offline Lars_J

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Edit: isn't whole stage black thanks to residues from engine burn?

Difficult to tell from the contrast in the video. Everything looks dark compared to the sky background.

Offline matthewkantar

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Couple of questions, can anyone tell if the legs deploy? Is the stage not plumb to the water or is that a misperception?

Matthew

Offline moralec

Edit: isn't whole stage black thanks to residues from engine burn?

Difficult to tell from the contrast in the video. Everything looks dark compared to the sky background.

It is still possible to see some detail on the booster.... is that the "SPACE X" sign still readable?.


Couple of questions, can anyone tell if the legs deploy? Is the stage not plumb to the water or is that a misperception?

Matthew

The on board video was uploaded a while back and it showed the legs deploying. 
« Last Edit: 08/14/2014 09:42 pm by moralec »

Offline Lars_J

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Here is a contrast enhanced shot, with another one that annotates the outlines. Note the white wedge shape near the bottom, which appears to be the "un-sooted" area of the booster protected by the folded legs.

It is also interesting to note how the LOX tank appears to be relatively clean, while the RP tank is very sooty. (?) There is a very clear border. Perhaps LOX tank was cold, and this prevented the condensation or soot mixture from sticking.
« Last Edit: 08/14/2014 09:59 pm by Lars_J »

Offline guckyfan

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Those two screen captures show quite clearly that the stage is very nearly vertical. It was a misconception that it is not.


Offline moralec

Moderators: Is it possible to merge this thread with http://forum.nasaspaceflight.com/index.php?topic=35243.0 ?

Offline SVBarnard

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So is that what the grid fins are for, to help keep the stage straight as it falls?

Online rcoppola

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Absolutely stunning!

I wish they had attached a figure as to how close they were to their intended landing coordinates. Regardless, they must be getting damn close if CRS-4 is going to go for a barge landing. 

Just stunning how smooth she lands. It looked as controlled and soft as any F9R Dev footage we've seen.

I see now why Elon stated with such certainty that they are ready to land this bird.
« Last Edit: 08/14/2014 10:11 pm by rcoppola »
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Offline Lars_J

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So is that what the grid fins are for, to help keep the stage straight as it falls?

Yes, to keep is straight and be able to aim it without using any propellant. But it was already straight in this video - the fins just add control.

Offline guckyfan

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So is that what the grid fins are for, to help keep the stage straight as it falls?

Actually no. Engine gimballing takes care of that during landing. The grid fins will be able to control the stage in the long flight phase when the engines are not running. They can do precision steering by forcing the stage body to a desired angle against the airflow, creating a steering force.

Offline junk.munk82

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enhanced video:

Offline SVBarnard

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So is that what the grid fins are for, to help keep the stage straight as it falls?

Actually no. Engine gimballing takes care of that during landing. The grid fins will be able to control the stage in the long flight phase when the engines are not running. They can do precision steering by forcing the stage body to a desired angle against the airflow, creating a steering force.

OK so at first when the the engine is not lit the grid fins will allow the stage to effectively glide? And as for this gimbaling, are you saying  the engine bell is able to literally move? I thought it was completely rigid?

like this pic shows?

« Last Edit: 08/14/2014 10:22 pm by SVBarnard »

Offline BrianNH

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Regardless, they must be getting damn close if CRS-4 is going to go for a barge landing. 

CRS-4 will be a water landing.  The two after it will be barge of some sort.

Offline somepitch

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Offline Llian Rhydderch

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So is that what the grid fins are for, to help keep the stage straight as it falls?

Actually no. Engine gimballing takes care of that during landing. The grid fins will be able to control the stage in the long flight phase when the engines are not running. They can do precision steering by forcing the stage body to a desired angle against the airflow, creating a steering force.

OK so at first when the the engine is not lit the grid fins will allow the stage to effectively glide? And as for this gimbaling, are you saying  the engine bell is able to literally move? I thought it was completely rigid?

like this pic shows?

The F9 first stage center engine gimbals. 

You can see it work in one of the early Grasshopper videos SpaceX released.  The links for all of those vids is in the Grasshopper Wikipedia article, under external links.  The gimbal movement was shown in the Ring of Fire (music video), of the 4th Grasshopper test flight.  See it at about 35 seconds into the video, and also shown is the rocket response.
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Offline Ohsin

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Looks like the camera ship is one of these:

http://www.diamond-sensing.com/index.php?id=da42mppguardian

That is one good looking plane light and sharp perfect for job! At 30 sec mark on video they switch to FLIR and zoom in that is why sudden switch to white background and stark black stage.

EDIT : Looks like the landing/splashdown is in Slow motion as well.
« Last Edit: 08/14/2014 11:09 pm by Ohsin »
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Offline cbarnes199

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I thought it was stated by Elon that the next two launches after Asian-6 will be land based not water based.  Wouldn't that include CRS-4?

Offline Kabloona

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Gwynne Shotwell reportedly said that the barge landing attempt could be "as early as" CRS-4.

Offline zlynn1990

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If they don't go for a barge landing on CRS-4, it would be cool if they put out some kind floating bulls eye target. I'm really curious how good their accuracy is without the grid fins. Do they currently have any flight control mechanisms other than the engines and RCS?

Online Chris Bergin

enhanced video:


That's great! There's a few frames of the core gracefully descending into the water there!
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Offline Elmar Moelzer

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Awesome! This looks really good!

Offline meekGee

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The amazing part is that it looks exactly like we've been imagining it.

It falls, it lights up, it lands.  Ho hum.

EDIT: fixed my phone's auto-corrupt.   "imagine king" ?!
« Last Edit: 08/15/2014 05:15 am by meekGee »
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Offline Dudely

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It is gloriously mundane.

Offline Comga

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enhanced video:
[youtube]lQCWQuM6p-w[/youtube]


Another candidate for best first post ever!
Nice work.
Welcome to the forum.


PS It's a lesson to all of us not to get greedy with zoom.  A moderate resolution image with the rocket in it is better than a high res image with the rocket half or fully out, particularly when it's zoomed beyond the resolution of the lens or the seeing like this.   However, it's still great to see what was captured.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Helodriver

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The way the pixels themselves expand during the rapid zoom at the end of the video leads me to believe this is a digital, not mechanical zoom that is applied to the video. It is quite possible this is an editing effect and a non overzoomed video of this landing exists. It is of course, completely up to SpaceX if they wish to release such video, much like they have not been willing to show the post landing "kabooms" of CASSIOPE and ORBCOMM.

Offline Norm38

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So much more detail is visible in the still captures.  We do see the final moments of flight.

Is it just me, or in this photo can we see where, outlined in black, the leg was folded up against the side?
It looks like the lower third is quite blackened by the braking burn, except where covered by the legs.

And after watching the enhanced video, I have no doubt this will come down on dry land exactly as expected.  Almost no difference between the last few seconds there and the F9R flights.  Doesn't look like they'll even need the New Mexico test flights.

Another note, we can see by following the leg mark on the side, that there is no rotation as it settles down.
« Last Edit: 08/15/2014 02:56 am by Norm38 »

Offline Ohsin

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The way the pixels themselves expand during the rapid zoom at the end of the video leads me to believe this is a digital, not mechanical zoom that is applied to the video. It is quite possible this is an editing effect and a non overzoomed video of this landing exists. It is of course, completely up to SpaceX if they wish to release such video, much like they have not been willing to show the post landing "kabooms" of CASSIOPE and ORBCOMM.

If it was digital zoom new details shouldn't emerge and image should degrade. But we only see it get better when it after zoom regains focus.
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Offline RocketGoBoom

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There has to be a lot more video they have not released. I am positive the plane would have flown over that spot, circled and there is tons of video of whatever was left of the rocket floating there. This was the landing where Elon tweeted "KABOOM".

Offline meekGee

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It's a lesson to all of us not to get greedy with zoom.  A moderate resolution image with the rocket in it is better than a high res image with the rocket half or fully out, particularly when it's zoomed beyond the resolution of the lens or the seeing like this.
A pet peeve of mine too...

As for digital zoom, if it was, then did they intentionally pan out the rocket?  That's (again) borderline tinfoil land.  They just missed the shot.  (again....)
« Last Edit: 08/15/2014 05:16 am by meekGee »
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Offline Comga

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It's a lesson to all of us not to get greedy with zoom.  A moderate resolution image with the rocket in it is better than a high res image with the rocket half or fully out, particularly when it's zoomed beyond the resolution of the lens or the seeing like this.
A pet peeve of mine too...
As for digital zoom, if it was, then did they intentionally pan out the rocket?
I see no evidence of digital zoom.
Can you capture a still that has uniformly large pixels as produced by digital zooming, and not just a few blocks like what would be expected for a noisy compressed video?

edit: wrong word corrected
« Last Edit: 08/15/2014 05:05 am by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline meekGee

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There were some concerns that the rocket looked off-vertical, just a second or two before touch-down.

We see here that it is vertical just at the end of the maneuver.

The computers have a guidance solution that is kinda like a launch in reverse.  In a launch (in this sense), the rocket is only vertical momentarily as it leaves the pad, and immediately starts tilting in order to follow its trajectory.

The "divert" maneuver will accentuates that.  It's not that the rocket will hover over point A, then translate over to point B.   It will come falling at an angle so that the instantaneous impact point is at point A (short of the pad) and then after the engine lights up, will shallow up and move the impact point to the pad.
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Offline Guspaz

While it doesn't look like digital zoom to me (the grain does't move outward), if it was, it could easily be the motion stabilization (in post) trying to keep the rocket in frame.

When you do motion stabilization in post, you have two options. Either you show the black borders of the original film shaking around, or you zoom in the image such that all movement of the borders is outside your new crop.

If you have a video with a varying amount of shake, you would change the zoom level/position gradually during the shot to keep everything in frame without cropping more than necessary.

The text in the video does say that they did motion stabilization on the video, but the youtube description also says that the operator was trying to zoom in to capture the "landing" in more detail and lost the shot:

"Towards the end of the video, the camera operator attempted to zoom in and unfortunately lost sight of the stage and was unable to capture the tip over into the water."

Offline Lars_J

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While it doesn't look like digital zoom to me (the grain does't move outward), if it was, it could easily be the motion stabilization (in post) trying to keep the rocket in frame.

When you do motion stabilization in post, you have two options. Either you show the black borders of the original film shaking around, or you zoom in the image such that all movement of the borders is outside your new crop.

If you have a video with a varying amount of shake, you would change the zoom level/position gradually during the shot to keep everything in frame without cropping more than necessary.

The text in the video does say that they did motion stabilization on the video, but the youtube description also says that the operator was trying to zoom in to capture the "landing" in more detail and lost the shot:

"Towards the end of the video, the camera operator attempted to zoom in and unfortunately lost sight of the stage and was unable to capture the tip over into the water."

Yep... That's how it looks to me. Digital zoom to 1) stabilize and 2) change composition. (as the rocket was drifting out of frame)

Offline docmordrid

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The way the pixels themselves expand during the rapid zoom at the end of the video leads me to believe this is a digital, not mechanical zoom that is applied to the video. It is quite possible this is an editing effect and a non overzoomed video of this landing exists. It is of course, completely up to SpaceX if they wish to release such video, much like they have not been willing to show the post landing "kabooms" of CASSIOPE and ORBCOMM.

If it was digital zoom new details shouldn't emerge and image should degrade. But we only see it get better when it after zoom regains focus.

I don't think those are magnified pixels in the zoom but video compression block artifacts.
« Last Edit: 08/15/2014 06:32 am by docmordrid »
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Offline Helodriver

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An artificial motion stabilization could produce the same effect I'm sensing, my background in making my assertion is watching a lot of long range digitally zoomed aerial video captured by USAF drones in various places. This has the same feel of post processing. A stabilization could produce the same effect.

Online ugordan

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The way the pixels themselves expand during the rapid zoom at the end of the video leads me to believe this is a digital, not mechanical zoom that is applied to the video.

It is possible (hard to tell due to Youtube's compression quality setting) that this is a blown-up crop of the original video, but I'm not seeing any digital zooming (that is pixels getting bigger) you see.

It is quite possible this is an editing effect and a non overzoomed video of this landing exists.

That theory might be supported by the Youtube thumbnail image for the video. Note the vignetting around corners indicating this is also a long lens shot. Same video source?


EDIT: replaced with a higher quality thumbnail.
« Last Edit: 08/15/2014 01:21 pm by ugordan »

Offline kevinof

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Wow. Very impressive. I've no doubt space-x could land this thing on a postage stamp if required. Looked very stable and very vertical. Just so weird see a stage coming back down (in a controlled way) again.

Offline JasonAW3

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For those wondering if the legs had deployed, it kind of looks like to me that the had deployed, but the triangular white sections on the hull of the rocket is where the soot from the reentry burn covered the hull.  when the legs deployed before touchdown, it left white triangles on the sides where the main hull was covered.

     At least that's what it looks like to me.
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Offline guckyfan

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For those wondering if the legs had deployed, it kind of looks like to me that the had deployed, but the triangular white sections on the hull of the rocket is where the soot from the reentry burn covered the hull.  when the legs deployed before touchdown, it left white triangles on the sides where the main hull was covered.

     At least that's what it looks like to me.

Why are the legs being discussed? We do have the onboard video showing them deploying.


Offline RoboGoofers

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I would be great to see a mashup of this video with the previous on-board video.

Offline meekGee

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Regarding digital zoom - wouldn't a professional setup like this allow you to fix any digital cropping that has occurred during digital zoom, and recover the panned out portions?   Or is this done on the camera sensor and the panned-out data discarded before there's a chance to record it?
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Offline Elmar Moelzer

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Optical zoom is almost always preferable to digital zoom in regards to image quality. Unfortunately it makes it much harder to keep the object framed correctly.
« Last Edit: 08/15/2014 04:17 pm by Elmar Moelzer »

Offline meekGee

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Optical zoom is almost always preferable to digital zoom in regards to image quality. Unfortunately it makes it much harder to keep the object framed correctly.

For sure - I always viewed digital zoom as something consumer-level cameras do because people are too lazy....

Unless there's a way for the camera sensor to get a higher resolution (or frame rate) by using only a portion of its area, it seems like a counter-productive practice.  And if it was done, then a panned-out object can be "un-cropped" by going back to the full recording.

Getting data on the sensor chip and then discarding it is just a recipe for regret.
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Offline rpapo

Somewhat different item: We notice that the rocket had a pretty much constant angle of attack to its descent in that video.  That begs the questions:

(1) Was this angle of attack deliberate, as a way to more precisely hit a specific target landing point?
(2) If it was deliberate, then how was it maintained?  The RCS doesn't have unlimited fuel.  Mind you, the entire lower atmosphere descent took less than two minutes, so I suppose it is possible.
(3) If it wasn't deliberate, then how did it happen?  Something assymetrical about the airflow around the nozzles?
(4) If it was deliberate, and was used for targeting, then why did the angle remain constant until just before the final touchdown?  Was the rocket still off target for landing, and the system trying hard still to make it to target?

Or was it simply crabbing into a crosswind?
« Last Edit: 08/15/2014 04:53 pm by rpapo »
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Offline OSE

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Somewhat different item: We notice that the rocket had a pretty much constant angle of attack to its descent in that video.  That begs the questions:

(1) Was this angle of attack deliberate, as a way to more precisely hit a specific target landing point?
(2) If it was deliberate, then how was it maintained?  The RCS doesn't have unlimited fuel.  Mind you, the entire lower atmosphere descent took less than two minutes, so I suppose it is possible.
(3) If it wasn't deliberate, then how did it happen?  Something assymetrical about the airflow around the nozzles?
(4) If it was deliberate, and was used for targeting, then why did the angle remain constant until just before the final touchdown?  Was the rocket still off target for landing, and the system trying hard still to make it to target?

Or was it simply crabbing into a crosswind?

Since we don't know the velocity vector of the rocket relative to the freestream air, we have no way to determine the AoA from the video. All we can say for sure is there are not large fluctuations of the rocket's orientation for the brief time we saw it. I think a very likely possibility is that AoA = 0.

Offline Lars_J

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Somewhat different item: We notice that the rocket had a pretty much constant angle of attack to its descent in that video.  That begs the questions:

(1) Was this angle of attack deliberate, as a way to more precisely hit a specific target landing point?
(2) If it was deliberate, then how was it maintained?  The RCS doesn't have unlimited fuel.  Mind you, the entire lower atmosphere descent took less than two minutes, so I suppose it is possible.
(3) If it wasn't deliberate, then how did it happen?  Something assymetrical about the airflow around the nozzles?
(4) If it was deliberate, and was used for targeting, then why did the angle remain constant until just before the final touchdown?  Was the rocket still off target for landing, and the system trying hard still to make it to target?

Or was it simply crabbing into a crosswind?

Or 5) there was no angle of attack (or looked worse than it was) - we are seeing a digital zoom into the corner of an image, where angles can be distorted. This is supported by the rocket not moving sideways.

Offline Joffan


Why are the legs being discussed? We do have the onboard video showing them deploying.


We have onboard video that shows 2 of the 4 legs deploying. I don't, myself, have any reason to expect the other two legs had any special problem deploying - but it's not actually demonstrated that they did deploy from the video you reference.
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Offline JasonAW3

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For those wondering if the legs had deployed, it kind of looks like to me that the had deployed, but the triangular white sections on the hull of the rocket is where the soot from the reentry burn covered the hull.  when the legs deployed before touchdown, it left white triangles on the sides where the main hull was covered.

     At least that's what it looks like to me.

Why are the legs being discussed? We do have the onboard video showing them deploying.

Someone meantioned taht the white triangle on the side of the craft made it look like the legs hadn't deployed.
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Offline Lars_J

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For those wondering if the legs had deployed, it kind of looks like to me that the had deployed, but the triangular white sections on the hull of the rocket is where the soot from the reentry burn covered the hull.  when the legs deployed before touchdown, it left white triangles on the sides where the main hull was covered.

     At least that's what it looks like to me.

Why are the legs being discussed? We do have the onboard video showing them deploying.

Someone meantioned taht the white triangle on the side of the craft made it look like the legs hadn't deployed.

Huh? That would only make sense if the legs were covered with some magic material that did not get dirty.

Offline Mader Levap

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Someone meantioned taht the white triangle on the side of the craft made it look like the legs hadn't deployed.
?? It is evidence of exact opposite. Legs deployed, uncovering parts of stage that didnt get dirted because legs covered this surface, protecting it during launch and reentry.
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Offline Avron

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Someone meantioned taht the white triangle on the side of the craft made it look like the legs hadn't deployed.
?? It is evidence of exact opposite. Legs deployed, uncovering parts of stage that didnt get dirted because legs covered this surface, protecting it during launch and reentry.

and then the sharks eat the stage.. without two of the legs.. or with both.. we don't know how many legs deployed

Offline GregA

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Slowing down the long shots to 1/4 of their speed makes the stage look very slow. I wonder if there's any possibility that "4x" was referring to zoom instead of speed. Then again, it was a long way away

I didn't slow down the final landing shots.

Also, the 1st long shot finishes almost at the horizontal, and the 2nd long shot starts looking upwards - so either there's a shot from a boat, or they've swapped the orders.

Also the mist from the long distance landing shots doesn't align with the exhaust from the side mounted cameras.

So just a draft with that 1/4 speed and order change, side by side with the side mounted camera footage. I haven't cut down anything they supplied, but I'd probably agree with the creative decision to not have it too long :)



Offline mme

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Slowing down the long shots to 1/4 of their speed makes the stage look very slow. I wonder if there's any possibility that "4x" was referring to zoom instead of speed. Then again, it was a long way away

I didn't slow down the final landing shots.

Also, the 1st long shot finishes almost at the horizontal, and the 2nd long shot starts looking upwards - so either there's a shot from a boat, or they've swapped the orders.

Also the mist from the long distance landing shots doesn't align with the exhaust from the side mounted cameras.

So just a draft with that 1/4 speed and order change, side by side with the side mounted camera footage. I haven't cut down anything they supplied, but I'd probably agree with the creative decision to not have it too long :)


I think you slowed down already slowed down footage.  So it went from 1/4 speed to 1/16 speed.

Thanks for all your work on this, I think it does a great job of telling the story. :)
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Offline Lar

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Why are the legs being discussed? We do have the onboard video showing them deploying.


We have onboard video that shows 2 of the 4 legs deploying. I don't, myself, have any reason to expect the other two legs had any special problem deploying - but it's not actually demonstrated that they did deploy from the video you reference.

You'd make a good Fair Witness. Point.
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Offline Lars_J

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I think you slowed down already slowed down footage.  So it went from 1/4 speed to 1/16 speed.
Yeah, at 1/16th speed is does become a bit ridiculous... Nice job though.

Offline Mader Levap

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and then the sharks eat the stage..
I don't think fate of stage was related to leg deployment, but to fact that stage "landed" in water.

without two of the legs.. or with both.. we don't know how many legs deployed
I will assume that all legs deployed untill proven otherwise. Do you have any evidence for this kind of failure?
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Offline Avron

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and then the sharks eat the stage..
I don't think fate of stage was related to leg deployment, but to fact that stage "landed" in water.

without two of the legs.. or with both.. we don't know how many legs deployed
I will assume that all legs deployed untill proven otherwise. Do you have any evidence for this kind of failure?


LOL.. we have been told the legs deployed and the stage went Kaboom.. no sharks where hurt in the stage non-recovery that we know of  :)

Offline meekGee

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Folks - I'm asking this in case someone has the video editing skills to pull it off:

It would be very beneficial IMO to "stabilize" the enhanced video, by forcing the plume to remain in the same spot on the screen.  (thus causing the borders of the video to jump around)

I keep thinking we could tease more information from the sequence if our eyes are not busy tracking the rocket on the screen.

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Offline ChrisWilson68

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here ya go:

Wow, great job!  That's even better than your first enhanced video.

Offline ChrisWilson68

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Optical zoom is almost always preferable to digital zoom in regards to image quality. Unfortunately it makes it much harder to keep the object framed correctly.

For sure - I always viewed digital zoom as something consumer-level cameras do because people are too lazy....

Unless there's a way for the camera sensor to get a higher resolution (or frame rate) by using only a portion of its area, it seems like a counter-productive practice.  And if it was done, then a panned-out object can be "un-cropped" by going back to the full recording.

Getting data on the sensor chip and then discarding it is just a recipe for regret.

There's a big difference between digital zoom for a still and digital zoom for video.  Very few cameras these days record every bit that comes out of the sensor when recording video, so you usually do get some advantage from doing a digital zoom in that more of what you lose is from outside the frame and you get to keep more of what you zoomed in on.

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DM

Offline douglas100

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Yes, well done and an excellent suggestion by meekGee.
« Last Edit: 08/17/2014 04:40 pm by douglas100 »
Douglas Clark

Offline Jcc

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Fantastic job on the video!

It appears to me  they had a small crosswind, going from right to left in the frame, since the water spray/vapor is asymmetrical and the stage was leaning a few degrees into the wind until touchdown. The last frames show the stage vertical, so perhaps the legs contacting the water righted it, or a final engine maneuver is designed to make the stage exactly vertical at touchdown.

Offline meekGee

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Thanks!   This is gorgeous...

I only later realized how much I was asking for...  this is probably a result of frame-by-frame manual panning, right?

---

I think we see a vent on the left side, just before touch down.
I kept hoping I'd see the legs, but I don't think I can.

And like everyone else, I can't wait for the barge-cam footage.   

Once it settles, and given that there's still full telemetry - how soon before ground crews get a green light to approach it?  (Supposing they were in a shelter right near by)
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Offline junk.munk82

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I only later realized how much I was asking for...  this is probably a result of frame-by-frame manual panning, right?

frame-by-frame but in a highly automated way, edit time was just about 10minutes

Offline meekGee

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I only later realized how much I was asking for...  this is probably a result of frame-by-frame manual panning, right?

frame-by-frame but in a highly automated way, edit time was just about 10minutes

:) glad to hear...

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Offline moralec

What an amazing video! Thanks so much junk.munk82!

Offline drjrkuhn

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Beautiful video!

I humbly suggest cropping the left and right sides so that the bouncing frames do not distract as much from the stabilized rocket image.

Offline Robert Thompson

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Excellent. How difficult would it be to draw an interpolated outline when the fov is off? Give the eye an anchor and give the intuition some sense of the angles. Someone else did an outline of the first stage in a sea landing.

Offline JamesH

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Optical zoom is almost always preferable to digital zoom in regards to image quality. Unfortunately it makes it much harder to keep the object framed correctly.

For sure - I always viewed digital zoom as something consumer-level cameras do because people are too lazy....

Unless there's a way for the camera sensor to get a higher resolution (or frame rate) by using only a portion of its area, it seems like a counter-productive practice.  And if it was done, then a panned-out object can be "un-cropped" by going back to the full recording.

Getting data on the sensor chip and then discarding it is just a recipe for regret.

There's a big difference between digital zoom for a still and digital zoom for video.  Very few cameras these days record every bit that comes out of the sensor when recording video, so you usually do get some advantage from doing a digital zoom in that more of what you lose is from outside the frame and you get to keep more of what you zoomed in on.

Exactly. If you have a 16MP sensor, note that HD video is 2MP, that's a lot of 'spare' MP's you can zoom in on without loss of detail. It can also be used for stills - the Nokia 808 camera phone used a 42MP sensor but had a 'digital' zoom in its 5 and 8MP stills mode that had no loss of detail. And the zoom in video modes is particularly impressive. These 'binning' modes also result in better noise reduction as the sensor can average over 2 or 4 or more pixels.

Offline MTom

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...
I kept hoping I'd see the legs, but I don't think I can.
...

Maybe it depends on my display but around 0:07 I could see for a very short time something like the piston on the right side of the rocket...

Offline meekGee

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...
I kept hoping I'd see the legs, but I don't think I can.
...

Maybe it depends on my display but around 0:07 I could see for a very short time something like the piston on the right side of the rocket...
At the his point if I stare at a blank wall for more than a minute, I can see legs deploying.

My wife commented on that during dinner, as my gaze was fixated on the wall opposite, instead of on the TV...

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Offline MTom

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...
I kept hoping I'd see the legs, but I don't think I can.
...

Maybe it depends on my display but around 0:07 I could see for a very short time something like the piston on the right side of the rocket...
At the his point if I stare at a blank wall for more than a minute, I can see legs deploying.

My wife commented on that during dinner, as my gaze was fixated on the wall opposite, instead of on the TV...

 ;)

I tried to capture a frame but none of the frames showing this entirely.
But while playing the video (not in full-screen), between 0:06 and 0:07 there can be seen a straight white line on the right. On the left side there is a plume at this moment, that's why only to see on the right.
Maybe this is not the piston, it could be also the leg, I don't know.
« Last Edit: 08/18/2014 11:15 pm by MTom »

Offline mvpel

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Keep an eye on when the "tan lines" appear on the body, that may help spot the leg on the right side.
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Offline Robert Thompson

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My eyes tell me the prominent tan line belongs to the leg on the right which has deployed perhaps 5 to 10 degrees from the viewer's pov. Look at the center line of the rocket, look at the line connecting plume to center of white band. Then look closely along the left side at the other tan line, from the leg on the left, which is then perhaps 80 to 85 normal to the viewer pov.

Add: And if I do many repeats just before the pov drops down, I can now see the left leg standing out prominently (80 to 85 degrees) as well as the right-MOST leg, not the right-very-center leg, which should be 100 to 105 degrees. Does anyone know the angle of the sun? I am figuring it is from the left.
« Last Edit: 08/19/2014 02:02 am by Hernalt »

Offline wronkiew

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Image stack of some of the frames from the YouTube video, with some extra alignment.

Offline Helodriver

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I'd been thinking about the attitude this stage was maintaining during freefall and if that angle was something being actively maintained by the RCS or was just how something weighted and shaped like that naturally falls through the atmosphere.

I'm beginning to suspect the latter, from an artifact of a different rocket, the first stage of the UKs Black Arrow R3 rocket launched in Woomera.

This stage survived reentry unpowered and freefell onto a cattle station in the outback after delivering the Prospero satellite to orbit, landing largely intact. The stage was liquid fueled with multiple engine bells much like the Falcon 9 v1.1. Upon impact the engine bells and one side of the stage's base show definite directional crushing, correlating with an impact slightly off the vertical, evidence of a Falcon like angled attitude assumed naturally without RCS guidance.

Offline S.Paulissen

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I have a really offtopic request for people who read this thread. 

Can anyone replicate what Junk.Munk did with this video (stabilization) on a different, much shorter video?  I have a scientific need for this and would greatly appreciate help with  stabilizing a video I made of a 3d projection of a cell. 
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Image stack of some of the frames from the YouTube video, with some extra alignment.

Is the dark color at the top of the stage from the 2nd stage ignition or some weird boundary layer heating on the way down.

Offline RanulfC

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I'd been thinking about the attitude this stage was maintaining during freefall and if that angle was something being actively maintained by the RCS or was just how something weighted and shaped like that naturally falls through the atmosphere.

I'm beginning to suspect the latter, from an artifact of a different rocket, the first stage of the UKs Black Arrow R3 rocket launched in Woomera.

This stage survived reentry unpowered and freefell onto a cattle station in the outback after delivering the Prospero satellite to orbit, landing largely intact. The stage was liquid fueled with multiple engine bells much like the Falcon 9 v1.1. Upon impact the engine bells and one side of the stage's base show definite directional crushing, correlating with an impact slightly off the vertical, evidence of a Falcon like angled attitude assumed naturally without RCS guidance.

With the propellant depleated (Black Arrow) or almost depleated (F9) the engines are the most mass and the vehicle "wants" to point with the most mass forward. The main "question" was how does in reenter since an "engines up/TPS covered stage interface down" angle would require active RCS through the point where the vehicle was rotated to an "engines-down" position for final retro-fire, while an "engine-first/down" entry would require much less RCS during the flight but subject the engines to full reentry heating and aerodynamic pressures.

What might have been :) A little more propellant and the Black Arrow might have been the first reusable rocket stage in history, it was robust enough for the job :)

Randy
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Offline nadreck



(snip)... while an "engine-first/down" entry would require much less RCS during the flight but subject the engines to full reentry heating and aerodynamic pressures. ...(snip)



Well, if I were hand waving and speculating wildly about reusable orbital stages (or much higher energy stages than the first stage of a Falcon 9), I would think that an engine designed for re-entry would use some of the residual fuel (not oxidizer except maybe enough to run a pump at very low power) to cool the engine during re-entry forming a protective layer as it vaporizes and heats up. In fact I can't help but think that there was nothing inherently wrong with a variety of schemes based on that like the George Detko ATV.  Some much larger scale versions of that were imagined, including ones that were not purely SSTO but disposed of fuel tanks that were side attached despite the vehicle being cone shaped (this got around the terrific volume penalty of using Hydrolox).
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline RanulfC

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(snip)... while an "engine-first/down" entry would require much less RCS during the flight but subject the engines to full reentry heating and aerodynamic pressures. ...(snip)



Well, if I were hand waving and speculating wildly about reusable orbital stages (or much higher energy stages than the first stage of a Falcon 9), I would think that an engine designed for re-entry would use some of the residual fuel (not oxidizer except maybe enough to run a pump at very low power) to cool the engine during re-entry forming a protective layer as it vaporizes and heats up. In fact I can't help but think that there was nothing inherently wrong with a variety of schemes based on that like the George Detko ATV.  Some much larger scale versions of that were imagined, including ones that were not purely SSTO but disposed of fuel tanks that were side attached despite the vehicle being cone shaped (this got around the terrific volume penalty of using Hydrolox).

ROMBUS, et-al? :)
http://www.pmview.com/spaceodysseytwo/spacelvs/sld017.htm

To be honest the F9 is a bit tall and skinny to gain full advantage of the technique but it could be possible with enough TPS along the sides of the upper half of the stage to ward off the heating. I've pointed to the report before but the wider the base the better the reentry heating and shockwaves are kept away from the upper half of the vehicle.
http://www.spacefuture.com/archive/single_stage_to_orbit_vertical_takeoff_and_landing_concept_technology_challenges.shtml

Since the engine bells don't present a "unitary" surface towards the atmosphere (as a plug nozzle or plug cluster does in the above designs) they wouldn't tend to present the necessary surface to allow a stable shockwave pattern to emerge during reentry. In fact the edges of the engine bells, the thinest and hardest to cool sections of the bell would be exposed to the most heating unless the engines were actually running at a very low throttle to use the exhaust(s) as a virtual heat shield. (Before you go to far down this road recall two things; 1) The M1D/V only "throttles" to 70% so that would be the thrust level of the center engine to create the "spike" and 2) that's going to be using propellant AND decellerating the vehicle at the same time)

IIRC Gary Hudson mostly used water as a heat sink in his designs, though Bono (ROMBUS et-al) and others tended to use the cryo-hydrogen, flowed through the base heat shield and then "dumped" overboard through the nozzles for reentry protection. I don't think RP1 would work as well but since F9 carries no water... :)

I suspect however from discussions that presenting a more "unitary" TPS covered " upper stage cover and using active RCS would eliminate "most" of the problems by giving a much bigger shockwave (shallower angle) so as to protect the lower-stage/engines from reentry heating. Albeit at the cost of more RCS control requirements and active reentry positioning because of the unstable entry angle over the more stable engine first position.

I'm of the belief (and in the minority here) that eventually SpaceX is going to have to go with squater, fatter more capable stages that can reentry "engines-first" to facilitate recovery and landing operations if they every really want to reduce the operational "turn" time for reuse :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline nadreck


(snip)... hand waving and speculating wildly ... (snip) ... I would think that an engine designed for re-entry ...
ROMBUS, et-al? :)

Very et al - lots of derivatives of those ideas out there - including one I had high hopes for in the 90's - the DC-X.

(snip)... I've pointed to the report before but the wider the base the better the reentry heating and shockwaves are kept away from the upper half of the vehicle. ... (snip)

Since the engine bells don't present a "unitary" surface towards the atmosphere (as a plug nozzle or plug cluster does in the above designs) they wouldn't tend to present the necessary surface to allow a stable shockwave pattern to emerge during reentry. In fact the edges of the engine bells, the thinest and hardest to cool sections of the bell would be exposed to the most heating unless the engines were actually running at a very low throttle to use the exhaust(s) as a virtual heat shield. (Before you go to far down this road recall two things; 1) The M1D/V only "throttles" to 70% so that would be the thrust level of the center engine to create the "spike" and 2) that's going to be using propellant AND decellerating the vehicle at the same time)

IIRC Gary Hudson mostly used water as a heat sink in his designs, though Bono (ROMBUS et-al) and others tended to use the cryo-hydrogen, flowed through the base heat shield and then "dumped" overboard through the nozzles for reentry protection. I don't think RP1 would work as well but since F9 carries no water... :)

(snip)

I'm of the belief (and in the minority here) that eventually SpaceX is going to have to go with squater, fatter more capable stages that can reentry "engines-first" to facilitate recovery and landing operations if they every really want to reduce the operational "turn" time for reuse :)

Randy

Yes, I totally agree. Lets imagine a BFR with a squat reusable first stage that puts one of the squat cones from the ATV derivative craft to an altitude where its plug nozzle based aerospike can work.  I think it is a given that the current Dragon TPS is perfectly adequate without cooling for the broad area of the base that we really only have to worry about expending enough fuel through the plug nozzles to keep them safe. By eliminating 300 seconds of ISP and starting in a virtual vacuum the ROMBUS et al designs suddenly are perfectly doable with today's technology(with only a bare minimum of arm waiving).
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline SoulWager

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I'd been thinking about the attitude this stage was maintaining during freefall and if that angle was something being actively maintained by the RCS or was just how something weighted and shaped like that naturally falls through the atmosphere.

I'm beginning to suspect the latter, from an artifact of a different rocket, the first stage of the UKs Black Arrow R3 rocket launched in Woomera.

This stage survived reentry unpowered and freefell onto a cattle station in the outback after delivering the Prospero satellite to orbit, landing largely intact. The stage was liquid fueled with multiple engine bells much like the Falcon 9 v1.1. Upon impact the engine bells and one side of the stage's base show definite directional crushing, correlating with an impact slightly off the vertical, evidence of a Falcon like angled attitude assumed naturally without RCS guidance.

With the propellant depleated (Black Arrow) or almost depleated (F9) the engines are the most mass and the vehicle "wants" to point with the most mass forward. The main "question" was how does in reenter since an "engines up/TPS covered stage interface down" angle would require active RCS through the point where the vehicle was rotated to an "engines-down" position for final retro-fire, while an "engine-first/down" entry would require much less RCS during the flight but subject the engines to full reentry heating and aerodynamic pressures.

What might have been :) A little more propellant and the Black Arrow might have been the first reusable rocket stage in history, it was robust enough for the job :)

Randy
While it's not really relevant for F9, that question is definitely relevant to the upper stage. If the Merlin 1Dvac masses around 700kg, I could definitely see a heat shield, superdracos, and landing fuel outmassing that, so if you put superdracos on the top of the stage you'd get a stable reentry, then land upside down.
« Last Edit: 09/24/2014 08:40 am by SoulWager »

Offline Dudely

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Albeit at the cost of more RCS control requirements and active reentry positioning because of the unstable entry angle over the more stable engine first position.

A rocket is just as stable backwards as forwards is it not? Pendulum fallacy and all that.

Offline Jakusb

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Albeit at the cost of more RCS control requirements and active reentry positioning because of the unstable entry angle over the more stable engine first position.

A rocket is just as stable backwards as forwards is it not? Pendulum fallacy and all that.

Try throwing a dart the wrong way around. The heavy part will attempt to overtake the lighter end. ;)

Online Chris Bergin

Ok folks, resist the temptation to post unless you are bang on topic here.

From this point onwards.
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Ok folks, resist the temptation to post unless you are bang on topic here.

From this point onwards.
Can we get a thread made for nose-first vs tail-first entry modes and have the off-topic material moved there? I think there's some good discussion here, it just doesn't belong here.

Offline RanulfC

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Ok folks, resist the temptation to post unless you are bang on topic here.

From this point onwards.
Can we get a thread made for nose-first vs tail-first entry modes and have the off-topic material moved there? I think there's some good discussion here, it just doesn't belong here.

Advanced Concepts, here or someplace else? Suggestions Chris?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline raketa

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