Autonomous Glider Ballooned to 10 km Altitude, Lands Safely 200 km Away

[Winston]

Autonomous Glider Ballooned to 10 km Altitude, Lands Safely 200 km Away
30 May 2018

https://hackaday.com/2018/05/30/autonomous-spaceplane-travels-to-10-km-lands-safely-200-km-away/

The goal of this project was to drop a glider from the edge of space using a high altitude weather balloon. The glider is entirely homemade and uses the opensource Pixhawk flight controller + a Raspberry Pi Zero to disconnect at the desired altitude and fly to a predetermined landing location. There is no direct radio contact with the aircraft, but we included a GPS tracker made for cars in case the glider didn’t make it to the landing site.

We tested the glider by first dropping it from a homemade quadcopter. This took 6 test-flights. Satisfied that everything was working properly, we prepared to launch the glider from the balloon. Although our target was 30km, we only had a few free days to launch, and on every day predictions showed that strong stratospheric winds would blow the glider hundreds of miles into the ocean if we launched from that height. We settled for a 10km launch altitude, and set the Pixhawk to land at a location within 20km of where the predictions estimated it would end up if it simply free-fell from the balloon.

We inflated the balloon, tied the glider to a long string to minimize swinging, and let it go. It was a two hour drive from the launch site to the landing location, and when we got there the glider was sitting on the ground roughly 10m from the target!

Max Altitude: 10.048km, 6.243mi
Max Speed: 95.5m/s, 212.5mph
Time Aloft: 2hrs 8min 18s
Dist Traveled: 195.95km, 121.76mi

THE GLIDER:
The glider is built from foamcore with coroplast for winglets and control surfaces, and laminated with colored tape for water-proofing. It carries two mobius cameras, two servos, a pixhawk flight controller with GPS, and a separate GPS/GSM tracker. Critically, all the electronics are inside the fuselage, which we packed with handwarmers and sealed shut before the flight to keep anything from freezing. Two 5200mAh 3s batteries provided more than enough power for a two hour flight (we were hoping to fly longer and higher). The takeoff weight was ~1300g.

THE FLIGHT CONTROL:
We used a Pixhawk for flight control. A Raspberry pi zero is connected to the pixhawk via USB and communicates with the Pixhawk using the Mavlink protocol. A simple python script on the Pi sets the flight mode on the Pixhawk to MANUAL on startup to prevent the servos from moving and wasting the battery during ascent. The script continuously checks the altitude, and when it reaches the target, triggers a solid state relay to burn a short piece of nickel-chromium wire, disconnecting the glider from the balloon. The script then sets the flight mode to AUTO, so the Pixhawk will direct the glider to a single target waypoint.
Source code: https://github.com/IzzyBrand/spaceplane

THE BALLOON:
The ballon is an old military surplus balloon I bought off ebay for $60. Not sure what the actual size was, there was little documentation. It came with a skirt which we cut off to save weight. We inflated it with half a K-tank of helium, though we probably could have gotten by with an S-tank. At launch, the balloon was generating a lift force of ~3000g. We used the https://habhub.org/ predictor to estimate the flight path and select a disconnect altitude of 10000m.

[video=youtube;q10gKcguXW0]https://www.youtube.com/watch?v=q10gKcguXW0[/video]

 

[r66astro]

Cool!

 

[Charles_McG]

Paper airplanes from space:
https://www.theregister.co.uk/2012/02/17/paris_guiness/
https://regmedia.co.uk/2010/05/18/paris_mission_summary.pdf

and

https://www.theregister.co.uk/2014/09/23/paris_record_broken/

and

https://www.theregister.co.uk/2015/09/03/paper_plane_launch_record/

 

[georgegassaway]

Very neat project. Pretty much anyone who knows how to use a Pixhawk Flight Controller (useful for both airplanes and multicopters) can program it to fly to a specific place and circle once there, even to do "autoland".

Using a different fiight controller with the same programming, I once set up an electric sailplane to fly itself back "home" and circle once back. Then in flipping a switch on the transmitter it did an autoland sequence, flying a pre-set landing approach pattern (base leg, crosswind leg, final approach) flying thru programmed aerial gateways (GPS coordinates at pre-set altitudes).

However, since this flew so high, into airliner territory, they may get contacted by the FAA about this if they did not have a waiver (not very likely there). Especially if the plane weighed over 250 grams (and it probably was well over that).

FAA absolutely monitors Youtube videos and goes after people whose videos self-incriminate that they flew illegally.

Of course, we see videos of people, even schoolkids using balloons to carry non-model things (toys, dolls, food, etc) plus cameras to document it up to what they often bogusly claim to be "space", without FAA approval. The balloon plus plus payload just as much danger (sometimes far more so) to manned aircraft than a multicopter flying at 500 feet could be, but I do not recall FAA going after any of them. FAA goes after modelers.

UPDATE: Perhaps they did have a waiver. In the comments section someone points out the FAA problem, and then a reply to that which may be by one of the people who did this says:

We had a NOTAM issued by the FAA for the airspace when it was flown.

Here's a video by Dave Windestal, of his "Space Glider" At least in the details he says "edge" of space. Anyway, he did this 5 years ago. But it was manually flown using FPV Video that had very high gain long range video. Nonetheless he lost video signal before the balloon popped at about 20 miles up (had intended to sep before it popped). By the time it got low enough for him to see it (regaining FPV video signal), he released the popped balloon, but the balloon ripped off an antenna which cut the range to 25% and he lost video again for long while. When he finally got good vidoe again, it was too low and too far away to make it across an enormous lake, so he landed it far away, near the side of a road. He was incredibly lucky to get it back. I'll also say for the record that Dave Windestal was among the pioneers of making COOL Multicopter videos.

Oh he did NOT get into trouble with the FAA. Because he lives in Sweden, and broke no laws there.

[video=youtube;rpBnurznFio]https://www.youtube.com/watch?v=rpBnurznFio[/video]

 

[Winston]

]Oh he did NOT get into trouble with the FAA. Because he lives in Sweden, and broke no laws there.

Back in 2013 when he flew was before the ridiculous drone hysteria hype, so there wouldn't have been any draconian RC aircraft rules anywhere in the free world that I know of to abide by and in the US there wouldn't be much more than the "fly nothing over 55 POUNDS without special permission" and "don't fly near airports" rules.

But, you know, the MASSIVE number of casualties from RC aircraft over the entire history of the sport has led to the 250g limit in many places (since other countries, idiotically in this case, blindly copy the FAA), a limit which anyone who read and understood the "study" used to determine it could see was a ridiculous WAG pulled from nether regions... just as the MASSIVE number of casualties from the millions of "igniters" shipped throughout the history of model rocketry has led them to be regulated, reformulated, and renamed as "starters".

This doesn't mean that I in any way endorse irresponsible behavior like RC flying anywhere near an airport or launching balloons without proper notification of the FAA and a radar retroreflector if required by the US free flight balloon regs. Idiots who violate rules and common sense ruin it for everyone because their actions usually lead to overregulation.

I believe I've posted previously here quite some time ago a video from some guys who did a high altitude glider balloon launch, but landed successfully back at the starting point in a US desert area.

 

[Winston]

If I had to list the most impressive amateur balloon accomplishment I'm aware of, it would be this great feat accomplished with something so small and inexpensive:

Balloon Flight B-66 / M0XER-6, 15 July 2014

https://www.leobodnar.com/balloons/B-66/index.html

Self-made plastic foil envelope. Circumnavigated the Earth 3 times.

Most of the last lap data is missing due to failing battery. B-66 stopped transmitting over Russia and appeared again over Atlantic near Ireland having travelled East. The track maps show this segment replaced with shortest path which might look confusing as it is "on the other side of the world."

Payload weight - 11 grams.
Downlink mode - 434.500MHz USB Contestia 64/1000 and APRS on regional frequencies. 10mW transmitter.
Start time: 15th July 2014 14:17 UTC
Last known position: 18th September 2014 18:35 UTC
Flight duration: 65 days (1564 hours)
Minimum track distance: 69583km (projected onto geoid, missing sections replaced by shortest path)

Payload and envelope are similar to B-64

 

[Winston]

The balloon flight seen below was in full compliance with the interesting FAA free flight balloon regs found here:

https://www.overlookhorizon.com/flight-safety/

[video=youtube;Cla34QzgbKc]https://www.youtube.com/watch?v=Cla34QzgbKc[/video]

 

[Winston]

Researchers say FAA is really overblowing risk posed by small drones
Small drones would damage aircraft once every 1.87 million years
3/15/2016

https://arstechnica.com/tech-policy...eally-overblowing-risk-posed-by-small-drones/

The Federal Aviation Administration has pushed forward strict rules for the operation of small consumer drones. Drones weighing more than 250 grams (a little more than half a pound) will have to be registered with the FAA, and there are restrictions on where they can be flown. The regulations are largely prompted by fears that the toy-sized flyers will pose a danger to commercial and civil aircraft—fears that new research suggests are unfounded. That research, shown in a study just published by George Mason University's Mercatus Center, was based on damage to aircraft from another sort of small, uncrewed aircraft—flying birds.

Much of the fear around drones hitting aircraft has been driven by FAA reports from pilots who have claimed near-misses with small drones. But an investigation last year by the Academy of Model Aeronautics (AMA) found that of the 764 near-miss incidents with drones recorded by the FAA, only 27 of them—3.5 percent—actually were near misses. The rest were just sightings, and those were often sightings that took place when drone operators were following the rules. The FAA also overcounted, including reports where the pilot said explicitly that there was no near miss and some where the flying object wasn't identified, leading the AMA to accuse the FAA of exaggerating the threat in order to get support for its anti-drone agenda.

There hasn't yet been an incident in which a drone has struck an aircraft. But bird strikes (and bat strikes) do happen, and there's a rich data set to work from to understand how often they do. Researchers Eli Dourado and Samuel Hammond reasoned that the chances of a bird strike remain much higher than that of an aircraft hitting a drone because "contrary to sensational media headlines, the skies are crowded not by drones but by fowl."

The researchers studied 25 years of FAA "wildlife strike" data, reports voluntarily filed by pilots after colliding with birds. The data included over 160,000 reported incidents of collisions with birds, of which only 14,314 caused damage—and 80 percent of that number came from collisions with large or medium-sized birds such as geese and ducks.

Despite the rise in reported bird strikes over time (largely driven by improvements to the FAA's reporting system), the number involving damage has remained relatively constant, numbering in the hundreds per year—a statistical blip, considering that there are approximately 27,000 commercial aircraft flights per day in the US. And in 25 years, there have been only 37 incidents of wildlife strikes that caused injuries or death. The most dramatic of them, the water landing of US Airways Flight 1549 in 2009, was caused by a flock of geese being sucked into both the plane's engines. The one commercial aircraft fatality was caused not by a bird strike but by a collision with a pair of deer during landing in 2000.

"On average, only 3 percent of reported small-bird strikes ever result in damage, compared to 39 percent of large-bird strikes," Dourado and Hammond reported. "Given the voluntary nature of strike reporting, the true percentage of strikes causing damage is probably much lower, as strikes that do not cause damage can be either missed or underreported."

Using the FAA data and bird census data, the researchers calculated the probability of airborne wildlife striking an aircraft. "In 2014, there were 13,414 reported collisions with birds and flying mammals, counting incidents in which flocks of birds hit an aircraft as a single collision," the researchers noted. "As there are on the order of 10 billion birds in US airspace, this means that plausibly 1 bird in 1 million collides with an aircraft every year."

Birds spend much more time in the air than consumer drones, which have a short battery life. Birds also don't necessarily avoid areas where airplanes are apt to hit them. Based on usage statistics, compared with bird behavior, the researchers estimated that for every 100,000 hours of flight time for drones weighing up to 2 kilograms, there would be 0.00000612 collisions causing damage to aircraft. "Or to put it another way," the pair wrote, "one damaging incident will occur no more than every 1.87 million years of 2kg UAS flight time."

And the frequency of injuries caused by drone collisions, they estimated, would be another two orders of magnitude smaller—happening once every 1.87 million years of operation. "This appears to be an acceptable risk to the airspace," they concluded.