This answer has a lot of images that I shouldn't need to repost here, and is supplemental to this answer to the question Help me understand what Farside, a ten “stage” rockoon looked like? How was it configured?

All available sources quoted in both answers state that Farside is a four stage rocket, with the 3rd stage being four parallel Asp's and 4th stage being a single one. But all images shown in both answers just seem to show the four cores of the 3rd stage topped with what looks like a large badminton birdie which is the payload.

Where is the fourth stage?

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    $\begingroup$ The 4th stage is the central cylinder in the bundle of 5 at the top of the vehicle. In the supplemental answer you posted, the lower right image on the first "page" shows the tip of the 4th stage and labels it as such. It's yellow in the color pictures. $\endgroup$ – Organic Marble May 19 '19 at 11:42
  • $\begingroup$ @OrganicMarble I am slowly getting the picture...,and so I've just asked How common are "parallel stages" in a launch vehicle? $\endgroup$ – uhoh May 19 '19 at 11:58
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    $\begingroup$ Did you see the balloon was made by General Mills? I wonder if it came packed with a toy inside. $\endgroup$ – Organic Marble May 19 '19 at 11:58

Pure speculation (just from looking at the photo): it's within the third stage.

While the cylinders for the first stage are either touching or nearly touching, the cylinders on the third stage are separated by a significant distance. It appears to be sufficient for a similar cylinder to be located within.

I have no idea why you wouldn't simply burn all 5 simultaneously as the third stage, but if that is how it's configured, it would match the numbers given.

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  • $\begingroup$ This really sounds plausible. Wouldn't 4 then 1 rather than 5 at once just be an example of staging? Tsiolkovsky etc.? $\endgroup$ – uhoh May 19 '19 at 9:03
  • $\begingroup$ As long as they're fired sequentially, yes I'd say they're true stages. I was just questioning what reason would be to do so. My assumption is that firing them simultaneously would be better for performance. But that's just my guess, not a calculation. $\endgroup$ – BowlOfRed May 19 '19 at 9:09
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    $\begingroup$ I'm now thinking that rather than the fifth cylinder in the center being captive, is a proper, separate stage that "shoots out" of the structure holding the other four when it's ignition time comes, leaving the four spent elements behind. $\endgroup$ – uhoh May 19 '19 at 9:13
  • $\begingroup$ Yes, it has to be able to release the earlier ones. Staging it separately would be a guaranteed loss if it couldn't drop the dry mass of the previous stage. $\endgroup$ – BowlOfRed May 19 '19 at 9:16
  • $\begingroup$ okay, in that case I can't understand why you said "I have no idea why you wouldn't simply burn all 5 simultaneously as the third stage..." Isn't the delta-v advantage of staging clear? $\endgroup$ – uhoh May 19 '19 at 10:34

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