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HomeAircraftHelicopterHelicopter Main Discussion › 33,000 ft vertical flight in a Drone
03-20-2018 01:17 PM  7 months agoPost 1
Heli_Splatter

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USA

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I really did not think that this was possible.
https://fstoppers.com/aerial/small-...tm_source=quora

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03-20-2018 01:43 PM  7 months agoPost 2
ssmith512

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Indianapolis, IN USA

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Whoa!
Heli_Splatter
I really did not think that this was possible.
I did not either.

Steve

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03-20-2018 03:13 PM  7 months agoPost 3
GyroFreak

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Orlando Florida ...28N 81W

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In the old Russia (Cold War Days) he would be tracked down by the KBG as a spy, sent to Gulag labor camp in Siberia or executed.
Man, how things have changed.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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03-20-2018 03:30 PM  7 months agoPost 4
Richardmid1

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Leeds, England

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Holy s***! -50C up there! I'm surprised the gyros etc still work at that temp!

60% of the time, it works every time!

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03-20-2018 03:44 PM  7 months agoPost 5
wjvail

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Meridian, Mississippi

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Friggen Russians have all the garden spots.

"Well, Nothing bad can happen now."

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03-20-2018 05:06 PM  7 months agoPost 6
wjvail

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Meridian, Mississippi

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Richardmid1
I'm surprised the gyros etc still work at that temp!
My guess is that the electronics, motor, RX, ESC, etc, loved the cold. I'd also guess that the battery had some form of heater and insulation. A thin covering of insulation and a chemical hand warmer would help a lot.

The gyros are another story. I'd have to study how MEMS gyros respond to extreme cold. Further, I have to believe the PID settings that work at zero feet would be less than optimal at altitude. The system control and damping at altitude would likely be wildly different than the extremely heavy air at the surface area.

https://www.metrology-journal.org/a...ijmqe130059.pdf

https://aip.scitation.org/doi/pdf/10.1063/1.5005260

"Well, Nothing bad can happen now."

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03-20-2018 05:30 PM  7 months agoPost 7
helitom

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Pine Grove, Calif, USA

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A question bigger than the low temp problems is, did this really happen? - it is a Russian source.

The older I get, the fewer things seem worth waiting in line for.

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03-20-2018 10:26 PM  7 months agoPost 8
Heli_Splatter

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USA

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Watching the video, the quad tumbled upside down a couple of times. It was able to right itself. At the end I was amazed how much power was left to fly back to point of origin. It has had me thinking all day.

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03-21-2018 12:01 AM  7 months agoPost 9
JuanRodriguez

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The Villages, Florida

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helitom
A question bigger than the low temp problems is, did this really happen? - it is a Russian source.
My sentiments exactly !

Been there, done that and old enough to know better.....

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03-21-2018 01:43 AM  7 months agoPost 10
wjvail

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Meridian, Mississippi

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Heli_Splatter
Watching the video, the quad tumbled upside down a couple of times. It was able to right itself.
My guess is that it was power off and was simply free falling. Most of my drones will right themselves given enough altitude.
Heli_Splatter
At the end I was amazed how much power was left to fly back to point of origin. It has had me thinking all day.
I assume it was a 4S 8,000mAh battery. At least that is what the telemetry suggests. If so it was very nearly dead when it landed and would suggest why they might have let it free fall for at least some of its decent.

"Well, Nothing bad can happen now."

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03-21-2018 01:57 AM  7 months agoPost 11
jbjones

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Columbus, Mississippi

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wjvail
I assume it was a 4S 8,000mAh battery.
He used 3 packs:

"4S with three packs in parallel"

So, what's the benefit of 3 smallish batteries, rather than 1 ~8Ah battery? Redundancy? I'm not up to speed on electric models.

J. B. Jones

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03-21-2018 02:17 AM  7 months agoPost 12
wjvail

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Meridian, Mississippi

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jbjones
"4S with three packs in parallel"
Oops. It does say that in the text. My personal drone uses a 4S 8Ah battery so it was easy to guess that might be what they uses. As for why they chose a 3P configuration, I couldn't say. Maybe it fit on their drone.?.? Maybe that's what they had?.?.

I can't see redundancy as a reason. You are more likely simply creating more failure points. You now have 12 cells instead of 4.

They landed with about 3 volts per cell and showed a total battery usage of 7,500mAh so I assume they were very close to dead, flirting with damaging their battery(ies) and started with a total capacity of 8,000mAh. I suppose it's possible they started with 3 x 3,300mAh packs for a total capacity of 9,000mAh but because of the temperature, they didn't see that capacity.

"Well, Nothing bad can happen now."

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HomeAircraftHelicopterHelicopter Main Discussion › 33,000 ft vertical flight in a Drone
03-21-2018 12:07 PM  7 months ago •• Post 13 ••
Richardmid1

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Leeds, England

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Another thing is the batteries will have been warming up as the temperature fell. I doubt the pack would have worked at all if they had started at -50C!

I personally thought he had gone inverted on purpose to drive the drone back down more quickly, it's difficult to descend quickly with a drone without losing prop speed and therefore stability. Descending upright, although at lower prop speed may have taken too long and therefore used more capacity.

60% of the time, it works every time!

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03-21-2018 01:54 PM  7 months agoPost 14
wjvail

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Meridian, Mississippi

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Richardmid1
I personally thought he had gone inverted on purpose to drive the drone back down more quickly, it's difficult to descend quickly with a drone without losing prop speed and therefore stability.
At first I also though they may have purposely flipped it over to make it descend faster - but if you look at it, they are descending at -30m/sec or more. That's 60+ miles an hour. My guess, it's free-falling and the props are windmilling. I don't think you could spin the props fast enough to add velocity to the decent.

I can't explain why the current doesn't go to (near) zero. Possibly the controller is still trying to stabilize itself even though is simply falling?

"Well, Nothing bad can happen now."

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03-21-2018 02:17 PM  7 months agoPost 15
Richardmid1

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Leeds, England

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wjvail
I can't explain why the current doesn't go to (near) zero. Possibly the controller is still trying to stabilize itself even though is simply falling?
I would say it definitely was otherwise it would be tumbling etc.

If the props were 'wind milling', I wonder if any charge gets fed back into the packs? I know on my DIY e-bike the pack voltage starts increasing when coasting down hill with zero throttle! Hey I wonder if the SAB mini comet does this in an auto?!

60% of the time, it works every time!

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03-21-2018 02:25 PM  7 months agoPost 16
wjvail

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Meridian, Mississippi

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Richardmid1
If the props were 'wind milling', I wonder if any charge gets fed back into the packs? I know on my DIY e-bike the pack voltage starts increasing when coasting down hill with zero throttle! Hey I wonder if the SAB mini comet does this in an auto?!
I wondered the same. I don't see the current go negative and I don't see capacity reverse. That could just be a telemetry limitation. If there was "regenerative windmilling" (yes I just created that term) I don't know if the props would be spinning that fast. The brake function on the ESC of my airplanes is powerful enough to spin the props off.

"Well, Nothing bad can happen now."

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03-21-2018 02:59 PM  7 months agoPost 17
GyroFreak

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Orlando Florida ...28N 81W

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While the brushless motors can act as 3 phase AC generators, the ESC is not designed to rectify and reverse the current flow to the battery. To do so would add greatly to the complexity (and reliability) for the tiny bit of regeneration achieved.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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03-23-2018 05:47 PM  7 months agoPost 18
GMPheli

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W. Bridgewater, MA USA

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Bl-heli esc's have a feature called "damped light" or "active braking". It alows the flight controller to maintain control when inverted under low power by using braking. So it allows you to have control while inverted. With this enabled voltage spikes are an issue. Voltage regulators or caps are required to stop fpv gear from frying from the momentary over voltage.

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