U-2 selfie with balloon

Baked Potato said:
Wouldn't you also have to know exactly how far away the balloon was?
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Nope. Not in this configuration.

You would need to know whether the plane was pointing so that the sun was exactly at its 9-o’clock position. If so, it’s a dead simple measurement requiring no geometry.
 
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Plot twist. Wasn't spying stuff on the ground. Was waiting for the spy planes to get close to spy on them.
 
Was hoping that pic would get released. So badass.
 
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Baked Potato said:
NoHeat said:
Perfect way to measure the dimensions of the balloon.
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Wouldn't you also have to know exactly how far away the balloon was?
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No, it's more a function of the distance of the light source. If the light source was a mile away, a few hundred feet closer or further would make a difference in the shadow. But the sun is 93 million miles away, and so much bigger than the Earth that the light rays are essentially parallel. Closer or further don't mean much.

Ron Wanttaja
 
wanttaja said:
No, it's more a function of the distance of the light source. If the light source was a mile away, a few hundred feet closer or further would make a difference in the shadow. But the sun is 93 million miles away, and so much bigger than the Earth that the light rays are essentially parallel. Closer or further don't mean much.

Ron Wanttaja
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True, but angles will matter. Which brings me to the comment that I think the pic is fake. Where’s the distortion of the shadow around the spherical shape of the balloon?
 
Dana said:
The picture was taken from the same direction as the illumination, so the distortion cancels out. From any other angle, yes, it would look distorted.
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I think you might be right. I'm not certain though.
 
ok, pulled the globe out into the sun and confirmed you are correct. Also, even at an angle the shadow wasn't as distorted as I was expecting it to be.
 
Thrusters or props maybe. Had to have some hp to overcome prevailing winds aloft I would think.
 
Piperonca said:
Thrusters or props maybe. Had to have some hp to overcome prevailing winds aloft I would think.
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Depending on the direction of the winds at various levels, too. Balloonists have long used varying wind directions to control their flight.

Bit skeptical of using any thrusters for maneuvering beyond some minor capability. The balloon's mass was on the order of 30,000 pounds if they were using hydrogen. Yes, it was lighter than air, but that doesn't mean massless. Whatever propulsion it carried would still need to move the mass.

Next time you're around a conventional hot air balloon, notice what happens if someone tries to pull it around by a rope. Doesn't happen fast, doesn't happen easy.

Ron Wanttaja
 
wanttaja said:
Depending on the direction of the winds at various levels, too. Balloonists have long used varying wind directions to control their flight.

Bit skeptical of using any thrusters for maneuvering beyond some minor capability. The balloon's mass was on the order of 30,000 pounds if they were using hydrogen. Yes, it was lighter than air, but that doesn't mean massless. Whatever propulsion it carried would still need to move the mass.

Next time you're around a conventional hot air balloon, notice what happens if someone tries to pull it around by a rope. Doesn't happen fast, doesn't happen easy.

Ron Wanttaja
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Agree on thrusters, certainly but how to do a figure-eight without some flight control surface? Even if changing altitudes some there has to be some serious F=ma going on, given all that m. Use those big solar array/antennas as sails?
 
Piperonca said:
Agree on thrusters, certainly but how to do a figure-eight without some flight control surface? Even if changing altitudes some there has to be some serious F=ma going on, given all that m. Use those big solar array/antennas as sails?
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Well, for one thing, consider, well... the font size. We're not talking a Pitts doing Cuban Eights in a small aerobatic box. Could make a pretty big "8" and still remain in sufficient contact to do useful intelligence with a ground target 50-100 miles away. I see "figure 8" as a typical dumbing-down of what is actually going on. I think it's more like an integral sign....

The solar arrays are at least an order of magnitude smaller than the balloon envelope itself...so doubt they help. Besides, if you're going to "tack," you need a keel digging into something. The balloon's inertia might serve to a small extend, but only for the most minor of course changes.

Another frame of reference, regarding moving that big 'ol mass: The diameter of the Hindenberg was pretty close to that of the balloon, and the Hindenburg massed about 500,000 pounds. It took four 1,200 HP engines to push it up to just 85 knots. DRAG would be a lot less for the Chinese balloon, of course, at least at altitude.

Ron Wanttaja
 
wanttaja said:
I see "figure 8" as a typical dumbing-down of what is actually going on. I think it's more like an integral sign....
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Was going to accuse you of a tacky comment but will refrain...
Swerves were more likely. Your accurate media at it again.
 
ELINT and/or COMINT capability, unsurprisingly.
 
The physics equations would be interesting to work out. In dead zero winds, a 1HP motor would be sufficient to maneuver the balloon. It would just move very slowly ... at first.

Unclear from the story: is that figure 8 lateral or vertical?
 
Piperonca said:
Was going to accuse you of a tacky comment but will refrain...
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Guess I'm wearing you down. :)

Swerves are more likely, as you say. I don't fault the media (much); this is WELL outside anything like their area of expertise, and for the most part, they don't know where to get better info. Somebody in the Government mutters, "Well, kind of a figure-8, but..." and this gets shortened to a definitive "figure-8".

Ed Haywood said:
The physics equations would be interesting to work out. In dead zero winds, a 1HP motor would be sufficient to maneuver the balloon. It would just move very slowly ... at first.
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It's interesting to note that the balloon had about the same diameter as the Hindenberg. The Zep had almost 5,000 total horsepower to push it up to a maximum of 85 knots. Sure, the balloon at 60,000 feet is going to have much less drag. But motors/fans located on the "gondola" are going to have a tendency to twist the vehicle around, more than push it...
balloon thrust rotate.jpg
Winds at 60,000 are typically pretty light, about 15 knots or so, and of course the air is thin.

Ed Haywood said:
Unclear from the story: is that figure 8 lateral or vertical?
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I was kind of trying to puzzle that out myself. I'm thinking, again, it's more of an integral sign, and is probably vertical.

Ron Wanttaja
 
wanttaja said:
It's interesting to note that the balloon had about the same diameter as the Hindenberg. The Zep had almost 5,000 total horsepower to push it up to a maximum of 85 knots. Sure, the balloon at 60,000 feet is going to have much less drag. But motors/fans located on the "gondola" are going to have a tendency to twist the vehicle around, more than push it...
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Yes less drag, but that means there will be less thrust as well. I really doubt that thing had any thrust capability at all.
 
Hang 4 said:
Yes less drag, but that means there will be less thrust as well. I really doubt that thing had any thrust capability at all.
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I figured the thrusters were to rotate and hold the balloon in certain orientations. Specifically to keep the solar panels oriented towards the sun.
 
TCABM said:
ELINT and/or COMINT capability, unsurprisingly.
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That’s what my late night reading says. Any reasonable person should have assumed that once they saw that apparatus hanging from the balloon.
 
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TCABM said:
ELINT and/or COMINT capability, unsurprisingly.
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And the funny thing is there's not much that they couldn't have gotten of that by driving by, or placing a remote sensor near, the facility. I can think of one signal that might be tricky but there are ways I assure you.
 
Pugs said:
And the funny thing is there's not much that they couldn't have gotten of that by driving by, or placing a remote sensor near, the facility. I can think of one signal that might be tricky but there are ways I assure you.
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This is why the US DoD and related three letter agencies were not that concerned about it.

Tim
 
tspear said:
This is why the US DoD and related three letter agencies were not that concerned about it.

Tim
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Then why do it? Makes no sense…if it’s nothing…and then start shooting down club science projects…are the three letter agencies that screwed up?
 
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