I am developing an unpowered paraglider system that will return the payload from a weather balloon to one of a few clear/open landing areas.  The idea is that depending on where the balloon bursts the Pixhawk will autonomously choose the best landing point (based on a pre-calculated prediction from software before ascent).  There are two main problems: the parafoil lacks any controls other than ailerons, and path planning to avoid being carried away by the wind.

Ideally, the Pixhawk would know to point itself into the wind, reducing ground speed to burn off excess altitude with minimal change in horizontal travel (basically keep heading into wind and GPS track towards target). As I understand it, the autopilot would instead try to head directly to the landing point and loiter down to it, pitching down to fight any overpowering wind.  This is a problem since there is no elevator and the parafoil would get carried away if the wind speed is greater than its cruise airspeed.

Are there any options within Mission Planner to achieve this result?  I assume I will need to edit the firmware to implement this new model, but I am unsure of where to start in the code.

I’m new to Ardupilot so any help is greatly appreciated!

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Hi Colin !

I'm currently working on a similar project, have you had any luck with your project ?
I'd be really interested discussing any progress you've made.

Jim

Since weather balloons fly against jet streams it's a good chance to have aerodynamic cell structure of your parafoil inflated by the wind.

You can read wind speed from GPS tracker coming with every weather balloon but need to precalculate safe descent trajectories to work for you if the balloon bursts.

Reversing your concept may give good results.

If you want to burn altitude using a parafoil, use a spiral dive (look for paraglider spiral dive on youtube). You will drift with the wind but will get to lower altitudes where wind speeds will be less extreme. Depending on the conditions and your flight envelope, it might be best to drift but spend less time in the high wind region than to waste time fighting against it. Of course, another way to increase your speed is to increase your wing loading, if your payload is reasonably robust, just use a small parafoil.

Regarding the software, have a look here. I don't think there is any stock firmware that handles parafoils but, if you feel like coding a bit, you might be able to just use an Arduino with GPS without needing a full blown Pixhawk.

@Andreas Gazis 

", another way to increase your speed is to increase your wing loading,

increase or decrease the speed ?

To solve the M$M worth problem how to save a payload in case weather balloon bursts

I work with operation research, heuristics, AI and live weather/ jet stream data.

Spiral dive is always uncontrolled, so a risk of failure is 99%

what may work and is reliable is built in stratospheric parachute

If your fly your weather balloons over unpopulated regions you don't need to care for clear/open landing area since you get landing place geolocated remotely.

Try to collect burst altitude for a type of weather balloons you fly

https://www.bing.com/search?q=weather+balloon+burst&qs=n&fo...

Always use recovery parachute, as advised below

https://www.basicairdata.eu/knowledge-center/design/introduction-to...

"The parachute will slow down the payload descent when the balloon explodes, during the ascent, the parachute is already exposed and hangs from the rigging.

Increase. Higher weight -> higher speed.

Spiral dive is never uncontrolled or it wouldn't be used as a standard descent manoeuvre in paragliding so your risk of failure is damn small. What you don't have control over is direction while doing it (you are just going in circles), since you are in a spiral so you drift with the wind (like you would with a normal parachute). However, you can exit whenever you feel like and then you have your foil's forward speed to point wherever you want to.

A complication you might have is deployment at altitude. Deployment from a stationary platform in the troposphere is no big deal, check out videos for paraglider D-bagging. However, trying it in super thin air, is an unknown. You might need to consider a pilot chute for stability until you are low enough to deploy the foil.

" can exit whenever you feel like

you are not correct

twist dive can be controlled at low speed only

https://www.bing.com/images/search?q=twist+dive&form=HDRSC2&...

BTW

deleting comments turns this thread into time-waster

Um, what?

What is a twist dive and what does it have to do with anything? I am talking about a spiral dive, see here:

https://xcmag.com/news/dive-dive-dive/

one of the most basic rapid descent tricks any paraglider pilots learns.

As to how much control one can have over the exit, please have a look at the following video:

https://www.youtube.com/watch?v=nH__8UbK1S8

(don't try this at home, chances are, you don't have enough space)

Not sure what you mean by deleting comments but I had been using the forward and back button in my browser before replying so that might have had unintended results. If that is the case, sorry, won't happen again.

I meant this reply have been deleted

Rescue parachute is pretested, verified and certified technique to save playload in  case of balloon's burst.

If you launch $100T+ weather balloons project you have to get insured against any risk ( all risk must be contained).

In case of paragliding, I recall my friend Alain from France, who have joined paragliding 40+ years ago and in that early days of paragliding,  half of a paragliding team of his friends already died in crashes.

Humans can control a dive, sensing more valuable data and processing the risk rescue as a number of interactive procedures and activities, actions.

I remember Pixhawk drones crashing frequently due to bug in software and in hardware, analyzing black boxes.

Watching  expert paragliders on video is not a real life.

Rescue parachute is a reliable technology, what you try to implement is high risk electronics + high risk mechanics, which can easily  fail at high altitude.

You need to invest your own money into your I Can Do It Project and take all the risks on yourself.

It may take years for such project to succeed to get weather balloon + payload insured, get all required certificates.

If your payload is worth $100 you risk nothing

If your payload is worth $100T  ( cameras, spectrometers, radiation sensors, computers ..) you risk everything

https://www.basicairdata.eu/knowledge-center/design/introduction-to...

"Descending Balloon

At the balloon bursts, the probe will initiate to fall back to Earth. To avoid mushing of the payload the recovery parachute should be correctly sized. Reusing ascending equations and replacing the parachute coefficient of drag C_{dd} instead of the balloon C_d we get the expression of vertical descending speed.

(4)   \begin{equation*} W_d=\sqrt{{2m_t} \over {C_{dd}A_d\rho}} \end{equation*}

Where A_d is the area of the parachute. Equation neglects the contribute of the payload drag, likely we will overestimate the descending speed.

Check your local regulations

follow up

did you count failed landings in your video (jumping into water) ?

https://www.youtube.com/watch?v=nH__8UbK1S8

Darius you are so wrong.....again. Deaths in paragliding have nothing to do with the discussion at hand and do not support your point in any reasonable manner. The spiral dive is a well tried and tested manoeuvre in the sport and is taught to all students, it's safe and controllable when used correctly and is highly effective in loosing height quickly whilst maintaing control. The evidence is available easily for anyone who cares to look for it. Try staying on topic and talking within your knowledge level.

d j said:

I meant this reply have been deleted

Rescue parachute is pretested, verified and certified technique to save playload in  case of balloon's burst.

If you launch $100T+ weather balloons project you have to get insured against any risk ( all risk must be contained).

In case of paragliding, I recall my friend Alain from France, who have joined paragliding 40+ years ago and in that early days of paragliding,  half of a paragliding team of his friends already died in crashes.

Humans can control a dive, sensing more valuable data and processing the risk rescue as a number of interactive procedures and activities, actions.

I remember Pixhawk drones crashing frequently due to bug in software and in hardware, analyzing black boxes.

Watching  expert paragliders on video is not a real life.

Rescue parachute is a reliable technology, what you try to implement is high risk electronics + high risk mechanics, which can easily  fail at high altitude.

You need to invest your own money into your I Can Do It Project and take all the risks on yourself.

It may take years for such project to succeed to get weather balloon + payload insured, get all required certificates.

If your payload is worth $100 you risk nothing

If your payload is worth $100T  ( cameras, spectrometers, radiation sensors, computers ..) you risk everything

https://www.basicairdata.eu/knowledge-center/design/introduction-to...

"Descending Balloon

At the balloon bursts, the probe will initiate to fall back to Earth. To avoid mushing of the payload the recovery parachute should be correctly sized. Reusing ascending equations and replacing the parachute coefficient of drag C_{dd} instead of the balloon C_d we get the expression of vertical descending speed.

(4)   \begin{equation*} W_d=\sqrt{{2m_t} \over {C_{dd}A_d\rho}} \end{equation*}

Where A_d is the area of the parachute. Equation neglects the contribute of the payload drag, likely we will overestimate the descending speed.

Check your local regulations

@ d j: Sorry, I do not understand where the assumption for super expensive payload comes from. This site is DIY drones, we discuss anything that is remotely capable of autonomous movement.

The OP asked about getting a parafoil to return from a balloon, presumably bursting at high altitude. There was no mention of payload price. The meteo community are using tried and tested methods because their equipment is expensive but that is their problem, this is a forum on DIY vehicles and these push the boundaries of what is currently available. A few years ago, we didn't have multirotors. Now they are fashionable and development is feverish. Before multis, we had airplanes and then multis became super fashionable and overtook them. Boats, sailboats and subs are possible but not so mainstream either. The focus of development is not necessarily dictated by what is possible but includes many factors.

Regarding the videos, the pilots ending up in the water are NOT failing. They are concluding their acro routine with gusto, over a lake, as part of an acro competition. A lot of them end up in the lake, irrespective of whether they decide to do a ground spiral or not (check out how small the landing platform is, they are flying small surface area, heavily loaded wings designed for extreme manoeuvrability). Incidentally the ground spiral is discouraged because of the high risk of the wing snagging on something on the ground, not so much of a problem over water but if you go all the way and touch a wingtip to the surface you are really asking for refreshing dip. What I am trying to demonstrate is that the spiral exit is VERY controllable, you are talking about a manoeuvre that can reach descent rates of 20 m/s (plenty fast to crunch your bones on impact) and yet competent pilots exit it with a margin of error of a couple of metres. Our use case here would be fine with a margin of error of a few hundred metres!

As to how easily an unmanned platform can perform it, have a look here at an RC paramotor going bananas:

https://www.youtube.com/watch?v=HTNVsTEmv70

The RC pilot is pulling off a complete acro routine, far beyond a simple spiral dive.

You said:

" spiral dive is a well tried and tested manoeuvre in the sport

exactly

weather balloon has nothing to do with any sport

weather baloon is not human controlled apparatus

But you are free to test and show us results of your tests, applying spiral dive rescue procedure to weather balloon when burst.

Watching carefully the video above you can easily see yourself that target landing failure rate by master sportsmen is high and risk is not contained.

I am always on topic: WEATHER BALLOON > RESCUE LANDING



RM Aviation said:

Darius you are so wrong.....again. Deaths in paragliding have nothing to do with the discussion at hand and do not support your point in any reasonable manner. The spiral dive is a well tried and tested manoeuvre in the sport and is taught to all students, it's safe and controllable when used correctly and is highly effective in loosing height quickly whilst maintaing control. The evidence is available easily for anyone who cares to look for it. Try staying on topic and talking within your knowledge level.

d j said:

I meant this reply have been deleted

Rescue parachute is pretested, verified and certified technique to save playload in  case of balloon's burst.

If you launch $100T+ weather balloons project you have to get insured against any risk ( all risk must be contained).

In case of paragliding, I recall my friend Alain from France, who have joined paragliding 40+ years ago and in that early days of paragliding,  half of a paragliding team of his friends already died in crashes.

Humans can control a dive, sensing more valuable data and processing the risk rescue as a number of interactive procedures and activities, actions.

I remember Pixhawk drones crashing frequently due to bug in software and in hardware, analyzing black boxes.

Watching  expert paragliders on video is not a real life.

Rescue parachute is a reliable technology, what you try to implement is high risk electronics + high risk mechanics, which can easily  fail at high altitude.

You need to invest your own money into your I Can Do It Project and take all the risks on yourself.

It may take years for such project to succeed to get weather balloon + payload insured, get all required certificates.

If your payload is worth $100 you risk nothing

If your payload is worth $100T  ( cameras, spectrometers, radiation sensors, computers ..) you risk everything

https://www.basicairdata.eu/knowledge-center/design/introduction-to...

"Descending Balloon

At the balloon bursts, the probe will initiate to fall back to Earth. To avoid mushing of the payload the recovery parachute should be correctly sized. Reusing ascending equations and replacing the parachute coefficient of drag C_{dd} instead of the balloon C_d we get the expression of vertical descending speed.

(4)   \begin{equation*} W_d=\sqrt{{2m_t} \over {C_{dd}A_d\rho}} \end{equation*}

Where A_d is the area of the parachute. Equation neglects the contribute of the payload drag, likely we will overestimate the descending speed.

Check your local regulations

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