Is this a Chinese spy balloon?

I would think all those ropes are there to give the gas bag some rigidity and to distribute the thrust evenly.

Not thought about it before, but as a wild stab in the dark, I'd guess the "dangling" ropes are for stability against roll.

The rope hanging off the downward side will apply its worsenning torque at a distance equal to the craft's radius times cos(roll).
The rope hanging off the upward side will apply a restoring torque from the still-free-hanging part with a distance equal to the craft's radius, and the rest of it at distance greater than that times cos(roll) (indeed greater than (1+cos(roll))/2) times the radius.

The latter always dominates the former. Therefore a restorative force is always present. Having longer ropes ensures that the majority of the restorative force has lever distance equal to the radius. (And note, I said "present", not "sufficient" :) )

This looks similar to the effects of the dihedral angle in winged craft (downside gets full lift, upper side gets less lift).
I may be far off but I think the dangling ropes are for mooring the aircraft before take-off, when they are untied or cut at ground level and left dangling in flight
The NASA Helios prototype solar powered UAV used very efficient wide chord propellers that were optimized for high altitude (upwards of 100k feet). It's possible something similar was utilized here.
Helios has 14 engines and not much drag, the Chinese balloon has 4 and a lot of drag. On the other hand, Helios is faster, which increases air resistance.
The wing span is 75m, twice the diameter of the balloon.
I see 48 separate solar panels.

Assuming those panels generate 350w to 600w each, that's roughly 17kw to 24kw of power generation. That's quite a bit of power.
Peak power? In winter, 2/3 of that power is spent charging the batteries during the day. So the average power draw would be 8kW at most; an 8kW engine has 10 horsepower. For comparison, the smallest engine in this B22 Bantam (Gross weight: 430 kg=948 lbs) has 48 kW.
Helios's engine power is 14×1.5kW; if China copied the design, 4×1.5kW seems sustainable by the solar power installed on that balloon.
Besides motors, what else would require that type of power?
if it's using air as ballast, the ballast pump would be a big low-pressure pump.
Passive ELINT receivers generally don't draw a lot of current (transmitters on the other hand...).

I'm not disagreeing with you necessarily, it's just another thing to think about.
How much power would be needed for heating?
As for bringing the solar cells into a better angle to the Sun... Wouldn't rotating the props eat up more power than the slight increase you'd get by adjusting the angle? Wouldn't they just add reserve generation capacity by adding more cells? The additional weight would be supported by a bigger balloon and the "free" lift.
Adjusting the angle horizontally would be mostly frictionless.
Single-axis trackers follow the position of the sun as it moves from east to west. These are usually used in utility-scale projects. A single-axis tracker can increase production between 25% to 35%. [...] Dual-axis trackers can increase energy production by about 40%.

I wonder if the platform is intended to be reusable. The typical "drop it on a parachute" method of returning the equipment back to ground seems a bit rough for a structure that big. If that balloon can land (on a calm day) by ballasting, the engines would certainly help it hit its designated landing spot.
I wondered about that as well. Not that difficult to install a severance system, like a ballistic guillotine or explosive bolt, to release the payload. Initiating it from a great distance via a radio link would be the more difficult part of such a design, but that challenge shouldn't be insurmountable.

Of course we won't know until the payload is recovered/analyzed, but it's doubtful there is advanced technology the Chinese would worry about being compromised if found by an adversary. Ditching it in deep, open water would make it far more difficult to recover, and almost impossible for that adversary to prove it's purpose was spying, however.

This is some high quality analysis, thanks for sharing that.

I guess I am going to revive this thread as I am getting off topic hits when I talk about it in the larger shootdowns thread (which ARE connected).

There is currently still debate regarding a few things re. the China Spy Balloon.

1. Was it a spy balloon or a weather balloon?
2. Was it "blown off course" and accidently flew directly over North America?
3. Did it collect signals intelligence and was it able to transmit that back to China?
4. Why was it not shot down BEFORE it traveled across the country?
5. What equipment was on the balloon?
5. Did it intentionally loiter over sensitive military bases using some propulsion/navigation mechanism?

Yesterday (12/6/2023) Congressman Russell Fry introduced legislation to get answers to these questions.

“The Biden administration sat on their hands and let this spy balloon freely fly across the country before shooting it down off the coast of my hometown of Surfside Beach — putting our country’s national security at risk and projecting weakness on the world stage,” said Congressman Russell Fry. “Almost a year later, we still don’t know the consequences of this administration’s lack of action. This legislation will provide Congress and the American people with answers on the effects this spy balloon had on our country’s national security.”
Content from External Source
Congressman Russell Fry introduces Chinese Spy Balloon Assessment Act
2. Was it "blown off course" and accidently flew directly over North America?
A Chinese balloon being blown off course predictably flies across North America, it has nowhere else to go.

3. Did it collect signals intelligence and was it able to transmit that back to China?
After the Navy raised the wreckage from the bottom of the Atlantic, technical experts discovered the balloon's sensors had never been activated while over the Continental United States.

4. Why was it not shot down BEFORE it traveled across the country?
We did assess that it was large enough to cause damage from the debris field if we downed it over an area. We had been looking at whether there was an option yesterday over some sparsely populated areas in Montana. But we just couldn't buy down the risk enough to feel comfortable recommending shooting it down yesterday.
Content from External Source
1. Was it a spy balloon or a weather balloon?
It's been termed a "surveillance balloon". It definitely was bigger and had more equipment on board than a "weather balloon", such as are released daily from many locations, would have. It's clearly a "high altitude platform" designed to operate at high altitudes fof exrended periods of time.

The Chinese claim it's a civilian balloon, while the DoD claimed its route showed that it was intended to collect military intelligence. If we have evidence on this, I missed it.

5. What equipment was on the balloon?
A better question would be, what equipment was recovered? This may remain classified. We do know that some of it seems to have been US-made.

Did it intentionally loiter over sensitive military bases using some propulsion/navigation mechanism?
From reviewing the press briefings, I doubt the balloon loitered. The DoD said that it overflew sensitive sites, and that it had the capability to manoeuver. I expect that if it had loitered, they would have mentioned that.
4. Why was it not shot down BEFORE it traveled across the country?
This was addressed at length back in February.
Q: And I have a follow-up question. Could you give us an estimate of how big the balloon was? We saw that it had solar panels and it could also potentially had a recording device on it.

GEN. VANHERCK: Yes, so the balloon assessment was up to 200 feet tall for the actual balloon. The payload itself, I would categorize that as a jet airliner type of size, maybe a regional jet such as a ERJ or something like that. Probably weighed in access of a couple thousand pounds. So I would -- from a safety standpoint, picture yourself with large debris weighing hundreds if not thousands of pounds falling out of the sky. That's really what we're kind of talking about.

So glass off of solar panels potentially hazardous material, such as material that is required for batteries to operate in such an environment as this and even the potential for explosives to detonate and destroy the balloon that -- that could have been present.

So I think that would give you an idea of the perspective of the balloon and the decision-making process along the way.

STAFF: Thank you, sir.

Q: Thank you.

STAFF: Let's go to -- let's go to Jennifer Griffin, Fox.

Q: Thanks, General VanHerck. Can I just ask you, on the record again, because there's been a lot made in recent days still about why this was not shot down after it crossed or neared the Aleutian Islands? Can you just explain what you were watching then, what you were thinking then? What the decision-making process was. And why it -- you didn't have enough time to do so, if that was the case?

GEN. VANHERCK: Thanks, Jennifer. It wasn't time. It -- the domain awareness was there as it approached Alaska. It was my assessment that this balloon did not present a physical military threat to North America, this is under my NORAD hat. And therefore, I could not take immediate action because it was not demonstrating hostile act or hostile intent. From there, certainly, provided information on the status of the whereabouts of the balloon. And moving forward, kept the department and the governor -- the government of Canada in the loop as my NORAD, I have a boss in Canada as well. Over.

Q: (inaudible), I'm still having trouble understanding the decision early on. You — you just said seven miles of debris. I mean, there must be parts of the Aleutian Islands and — and Canada that are so — so sparsely populated that there are fewer civilians per square mile than there are off the East Coast of the United States. So was it really just what might happen to people on the ground or was — was it the fact that you weren't ready to take a shot early on?

SENIOR DEFENSE OFFICIAL: I'll say that we were consistently assessing the threat that this ballooned posed. At the point that we thought that it posed a potential threat to us here in the continental United States, we started developing options. And at that point we decided that the risk-reward was not worth taking it down over land. And we waited for it to go over more.

Q: But that — that sounds like it was — it was too late to take a shot by the — by the time you realized it was an intelligence threat to the United States.

SENIOR DEFENSE OFFICIAL: We — we assess that it was not a considerable intelligence threat to the United States, because we don't think the technology on this balloon provided significant value-added over and above what the PRC already had. And we also took additional mitigation steps along the path of the balloon.

So we were constantly assessing the threat that this balloon posed to civil aviation, to anybody on the ground, to the intelligence value. And doing the risk-reward, about whether it was worth bringing this thing down over land, we ultimately decided it was the least risky option to bring it down over the water, and that's what we did successfully today.

STAFF: Thank you.

Ladies and gentlemen, we only have time for a couple more questions. The next question will go to Jennifer Griffin, FOX.

Q: Thanks. I just need — I'm really confused about why not take — I understand why not take it down over land after January 31st, but after January 28th, when it crossed over Alaska, and then it's my understanding it crossed over water again, why not take it down over the water at that time before it entered the continental United States?

SENIOR DEFENSE OFFICIAL: The options presented to us were to take it down over the continental United States or over the water.

Q: So does that suggest you only began — when did you begin tracking this balloon?

SENIOR DEFENSE OFFICIAL: The balloon entered the ADIZ north of the Aleutian Islands on January 28th. It then entered Canadian airspace on January 30th. It entered the continental United States airspace on January 31st, just in northern Idaho. And I would kick it out to our senior military official for any additional operational detail.

SENIOR MILITARY OFFICIAL: Thank you. Jennifer, I would say that it really didn't go back out over the water. Once it entered over Alaska, it stayed over Alaskan physical territory, traversed east across the northern part of Alaska and then into the Northwest Territories in the far northwest portion of Canada before it came back south into the Idaho area.

So there was not really a specific water shot there, opportunity at that point.

Note that of the 3 objects shot down subsequently, 2 were shot down over water as well, and the one that was shot down over land was over a largely uninhabited region of Canada, and it was much smaller.
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