Australia eats satellites
Australia: 2 (Skylab was the first)
A drone that Airbus once flew for 25 days without landing and suggests as either an airborne communications platform, or a stratospheric spy, broke up after its automation failed in rougher-than-expected weather. So says the Australian Transport Safety Bureau, which yesterday released its investigation into the September 2019 …
I've actually seen the Zephyr platforms, and they are incredibly fragile. A strong person could easily lift one up if they wanted to, but a weak person could, with the slight assistance of a length of 2-by-4, just as easily render one fit for nothing but a scrapyard. This is a common problem for all HAPS; I was once involved in flight trials on another platform that could not be launched on the expected day because it was far too windy - 5 mph being consider far to windy for that platform.
fragile air frame, the down side of having to make it uber-lightweight for solar panels to power it.
(back to the drawing board, or in their case, probably a cube farm of workstations running CAD software)
I bet there were similar design problems with that human-powered aircraft from a while back. It took many tries before a "working" one could be built [and I think it actually flew on ground-effect]
there are probably some interesting "exotic material" possibilities with making it even lighter weight than before, so that the rest of the airframe could be 'beefed up' a bit... hybrid materials involving carbon fiber, boron, aluminum, and so on. Maybe even use SMT tech inside the motor [example, a 'folded' inductor] and some kind of uber-light-weight electronic solder for the electronics (like maybe conductive glue?) Dunno if they're doing those things.
yeah, a soldered circuit board weighs quite a bit more than one without any solder on it... especially when soldered by someone who thinks "the bigger the blob, the better the job"
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First time I heard about HAP/HAPS/etc. ideas was something like mid 1990s. The concept failed after some considerable amounts of R&D funds were wasted - and after that the same idea have resurfaced 1-2 times before these latest developments.
It seems like this is some kind of perpetual machine - all the lessons learned are forgotten in less than decade and someone (sufficiently influential) comes up with "new bright idea" and the cycle starts all over again.
> It seems like this is some kind of perpetual machine
Err, one that has an input voltage from the solar cells covering it to power control systems and some form of propulsion (2x props, from the looks of the pics) to take it from ground to 70,000 feet and assist in maintaining altitude.
Perhaps it failed in the 90s, but materials science has no doubt come a long way in providing a lightweight airframe from which you can hang a payload of electrical gubbins
Technology changes as alternatives are proposed and tried in the real world. If YOU flap your arms and jump off a cliff then it's quite likely YOU won't learn but OTHERS will. The lessons they take away might differ. Sometimes it's a breakthrough application of new technology, others more experience, more understanding and improved tools.
I dunno, I had a car salesman recently tell me that the regen braking on the new electric Renault Zoe was, and I quote, "So good that if I took it for a short drive I'd end up with more battery charge than when I set off"...
"So" I asked innocently, "if I split my long journey up into lots of short ones I wouldn't need to recharge?"
long time ago, really far far away, I did a complete circuit without turning more than 30 degrees. Steady strong wind, increasing at height in a flat, flat wheat growing area above isolated airfield. It is weird "backing" an aircraft downwind but interesting easy challenge. No, no-one else up that day.
I hope you're not talking about the mythical "stall while turning downwind". Because as far as flight (and not navigation) is concerned, an airplane is completely oblivious to the direction and speed the surrounding air is moving relative to ground.
If you crash a powered aircraft you RUN from the wreck to avoid the fireball when the kerosene in the fuel tanks explodes. Or, you rescue other people on the plane and take the risk.
As for my instructor, it was last millennium, and I was learning to fly gliders in a place over 100 miles from the sea. In any case touching down on water one not expect to have to swim, but step into a boat or onto a wharf, though I acknowledge that Capt. 'Sully' did a pretty good one on the Hudson River a few years ago.
Every aircraft has a Va - max maneuvering speed. Above that speed, normal control inputs can result in structural damage. There is also Vne - never exceed where structural damage can occur without maneuvering.
To keep the weight down for flying at low density altitudes, the drove would be quite fragile and turbulence could easily go above Va or Vne.
The spin is as old as airplanes. Some are more susceptible than others, but an unrecoverable spin is always on the cards and the G forces can get high. As this would appear to be a somewhat lightly built airframe, the outcome is not entirely unexpected.
Err, not quite correct. If G-forces increase until the airframe breaks up, the aircraft is in a spiral dive, not a spin. Spiral dives, if not corrected, always end up destroying the airframe, usually by disintegration as airspeed exceeds VNE (the maximum rated airspeed) or by impact with the ground.
Spins are totally different to spiral dives: they are a more or less stable state, which is why they killed so many in the early days of flight: the pilot must take action to stop a spin, but in the early days: nobody knew how to do that. This is why spin recognition and recovery is, or should be, an essential part of pilot training.
In a spin, one wing, the one the plane is turning towards, is fully stalled while the other wing is generating lift, so the descent is relatively slow. What happens if the spin as allowed to continue depends in the aircraft: a few will self recover (e.g. an SZD Junior glider with a light pilot), with some (a Puchacz aerobatic glider after 10-12 rotations) the rotation rate increases and the descent rate slows because both wings are now lifting (this is known as a flat spin) while other aircraft continue to spin at the same rate until they hit the ground.
Because a spin is fairly stable, the pilot must take action stop the spin, and to do that one has to know how to stop a spin as well as to recognise spin entry and to take action while still high enough to avoid hitting the ground during recovery.
Bottom line: the Zephyr broke up it the air, so it either hit turbulence strong enough to overstress it or got tipped into a spiral dive which its control systems failed to recover it from before it broke up.
Yeah, every glider pilot knows that and is expected to demonstrate it during flight test. But do power pilots learn it? Anything as big and fragile as these drones needs to be flown more like a glider than a Cessna 150, even though most gliders are actually built quite strongly.
These things are probably fine at 70,000 meters where the wind is generally pretty clean. Getting them up there involves lots of potential problems. I'd imagine once you can get one to fly on pv for several weeks then you can make loads and clutter up the skies losing a few on the way up and down because the wind will just tear something that fragile apart. Any experienced pilot will have a story of some kind involving clear air turbulence.
> The nice thing about unmanned is you get to decide
Except that there's still 100KG of drone potentially arriving unannounced on someone's head if it's not a controlled descent. Yeah, the GAFA* is pretty empty but this is just the testing phase - real deployment is going to be from places slightly more populous.
[*] Great Australian Fuck All
"real deployment is going to be from places slightly more populous."
With an "up to" 90 day flight time and being very, very delicate, most places you want them will not have suitable launch conditions frequently enough so you'll probably launch from somewhere likely to have nearly constant, or at least predictable, calm weather and then just fly to the required part of the world.
It was a dead end, nobody wanted to part with enough cash to keep the project going*.
Also there must only be about 2 days a year when launching this from the UK is possible.
*This is completely opposite to the normal UK flight development practise of going over budget, delivering late and then being cancelled just as soon as everything is made to work properly.
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