balloon project - nasawing / parawing info

[Al Johnson]

This came about as a longer term aim for balloon landing, giving the potential
for the payload to fly itself back to a predetermined landing site. However
even with no control it has an advantage over a conventional parachute as it
will be smaller and lighter for a given descent rate. It's for this reason
that they're sometimes used in model rockets.

Wikipedia has some background:
https://en.wikipedia.org/wiki/Parawing

Here's a 2-part article on making a single keel wing for model rocketry:
https://www.apogeerockets.com/education/downloads/Newsletter206.pdf
https://www.apogeerockets.com/education/downloads/Newsletter207.pdf
The author also sells details for a dual keel wing:
https://www.apogeerockets.com/Rocket_Books_Videos/Pamphlets_Reports/
Tech_Pub_7?zenid=u7ur6cui7l26mov2u59k4k38i2

I first came across these as kites rather than parachutes. They split the
bridle lines into 2 or 4 groups to provide control. For 2 lines these are
left and right, which steer it by rolling the wing. The 4 line ones add brake
lines on the trailing edge and/or control of the angle of attack on left and
right. Note that even the smallest of these are considerably larger than we'll
be needing! This site has links to the original NASA research papers, plus a
number of variations for use as kites:
http://2e5.com/
These two in particular cover one of the designs and its construction in some
detail:
https://pdj.home.xs4all.nl/nasaplan.htm
http://www.pawprince.com/pawprince/design/kites/construct/home.htm

ArduPilot includes Rally Points - so you can predefine more than one 'safe'
place to aim for. It has gliding modes, but I don't know if it's been used
with controls as limited as a parachute before. It may just be overkill...
http://ardupilot.org/plane/docs/common-rally-points.html

This old thread shows people have been thinking about it for a while, but I've
not found anything more recent:
http://diydrones.com/profiles/blogs/slightly-of-topic-ardupilot?
id=705844%3ABlogPost%3A58316&page=2#comments

[grant gibson]

Al,

When I broached the subject on the high altitude balloon uk forum the feedback I got was that currently nobody is doing this kind of thing. They said it's totally possible however you need to submit a impact assessment for every possible failure mode to the caa before launch. They then deem whether your proposed recovery method is safe or not however the main caveat I was told was that there is a minimum safe decent rate which is actually quite slow so the controlled kite style decent would need to be made/deployed in such a way that if the electronics failed to operate correctly it can descend safely ideally as vertically as possible. What I think we would need to do is a number of lower altitude flights where we deploy and test the system and then use this data to submit with the risk assessment pack. It would be the same for the dual deployment option. If we need to launch a rocket or two to test the mechanisms I can design one that will go to a couple of thousand feet no problem. Alternatively we could use drone deployment to test it out.

I think if we did it it would make some ripples in the community for sure as it would be novel

Regards

Grant

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[Tony Brookes]

I’m next at the RCMGB on the 21st, and it sounds like you’re skating out phase 2 of the HAB project. Launch 1 & 2 I would like to be simple, L1 Raspi standard & comms, L2 Amateur radio comms standard (if one exists - I don’t speak that stuff (yet, fingers crossed). 

Why not use a kite as the host for the really low altitude stuff & launch within a controlled area - I can think of at least 1 in Derbyshire, but haven’t talked to them yet. Plus we’re likely to find it easier to get permission from 2 other friendly land owners I can think of.

I’ll carry on listening, but please carry on thinking aloud, it’s making my project plan so much easier to write…….

Tony

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[Al Johnson]

This would certainly be for a later phase, once we've some experience with
balloons - especially how much the payload may be spinning/tumbling at burst,
and how a parachute behaves at high altitude.

As for testing, friendly landowners would be good to know, as would anyone
with RC model aircraft.

> > <mailto:al...@adj.org.uk>> wrote: This came about as a longer term aim

> > for balloon landing, giving the potential for the payload to fly itself
> > back to a predetermined landing site. However even with no control it has
> > an advantage over a conventional parachute as it will be smaller and
> > lighter for a given descent rate. It's for this reason that they're
> > sometimes used in model rockets.
> >
> > Wikipedia has some background:
> > https://en.wikipedia.org/wiki/Parawing
> > <https://en.wikipedia.org/wiki/Parawing>>
> > Here's a 2-part article on making a single keel wing for model rocketry:
> > https://www.apogeerockets.com/education/downloads/Newsletter206.pd
> > f

> > <https://www.apogeerockets.com/education/downloads/Newsletter206.
> > pdf>
> > https://www.apogeerockets.com/education/downloads/Newsletter207.p
> > df
> > <https://www.apogeerockets.com/education/downloads/Newsletter207.
> > pdf>>

> > The author also sells details for a dual keel wing:
> > https://www.apogeerockets.com/Rocket_Books_Videos/Pamphlets_Report
> > s/
> >
> > Tech_Pub_7?zenid=u7ur6cui7l26mov2u59k4k38i2
> > <https://www.apogeerockets.com/Rocket_Books_Videos/Pamphlets_Reports/Tech
> > _Pub_7?zenid=u7ur6cui7l26mov2u59k4k38i2>
> >
> > I first came across these as kites rather than parachutes. They split the
> > bridle lines into 2 or 4 groups to provide control. For 2 lines these are
> > left and right, which steer it by rolling the wing. The 4 line ones add
> > brake lines on the trailing edge and/or control of the angle of attack on
> > left and right. Note that even the smallest of these are considerably
> > larger than we'll be needing! This site has links to the original NASA
> > research papers, plus a>
> > number of variations for use as kites:

> > http://2e5.com/ <http://2e5.com/>

> >
> > These two in particular cover one of the designs and its construction in
> > some>
> > detail:
> > https://pdj.home.xs4all.nl/nasaplan.htm

> > <https://pdj.home.xs4all.nl/nasaplan.htm>
> > http://www.pawprince.com/pawprince/design/kites/construct/home.ht
> > m
> > <http://www.pawprince.com/pawprince/design/kites/construct/home.h
> > tm>>

> > ArduPilot includes Rally Points - so you can predefine more than one
> > 'safe'
> > place to aim for. It has gliding modes, but I don't know if it's been used
> > with controls as limited as a parachute before. It may just be overkill...
> >
> > http://ardupilot.org/plane/docs/common-rally-points.html
> > <http://ardupilot.org/plane/docs/common-rally-points.html>>
> > This old thread shows people have been thinking about it for a while, but
> > I've>
> > not found anything more recent:
> > http://diydrones.com/profiles/blogs/slightly-of-topic-ardupilot

> > <http://diydrones.com/profiles/blogs/slightly-of-topic-ardupilot>
> > ?>

> > id=705844%3ABlogPost%3A58316&page=2#comments
> >
> >
> > --
> > You received this message because you are subscribed to the Google Groups
> > "Derby Makers" group. To unsubscribe from this group and stop receiving
> > emails from it, send an email to
> > derby-makers...@googlegroups.com

> > <mailto:derby-makers%2Bunsu...@googlegroups.com>. To post to this

> > group, send an email to derby-...@googlegroups.com

> > <mailto:derby-...@googlegroups.com>. Visit this group at
> > https://groups.google.com/group/derby-makers
> > <https://groups.google.com/group/derby-makers>. For more options, visit
> > https://groups.google.com/d/optout <https://groups.google.com/d/optout>.

[Al Johnson]

Hi Grant,

Thanks for that - I hadn't realised you'd already asked people about it.

I thought there would be a process like that for the CAA, similar to the
safety cases for tests or modifications on the railway. It's been a while since
I was involved in those. The other thing I'd imagine might be an issue is what
they class it as - does having steering and a glide angle turn it into a UAV
that has a whole other set of rules to follow? I know there's been at least
one balloon launched glider controlled by ardupilot, but that was a few years
ago now and rules around drones have changed I think. It's worth finding out
about this early though - it could be a blocker to the whole idea.

I agree on the need for testing. I'd expect this to be developed as a multi-
stage thing in parallel with the balloon side, considered for use only when
we've got enough data to have confidence in it. That would include:

* tests as a kite - to demonstrate stability, tune bridling, measure lift /
drag ratio and get an idea of the range of control input needed for steering.

* drop tests from kite or drone - to test deployment, static steering trim,
descent rate at low altitude etc.

* perhaps fly it as a paramotor under remote control or via ardupilot

I hadn't thought about using rockets for testing, and have no idea about the
rules around them. It might be a viable way of getting enough altitude to test
the guidance though. My kite use is with ~30m lines, so not a lot of altitude
to play with.

So far as making a case to the CAA, it's not a novel parachute design which
should make things easier. I'd avoid mentioning kites at all - it was
originally designed and tested as a parachute.
* Apart from NASA's research there's the model rocketry use, and there's at
least one manufacturer selling them as a fully approved backup parachute for
paragliders.
* The rocketry usage gives descent rate calcs for similar size and loading,
which we should be able to back up with drop test results.
* With static trim for a steady circling it would descend in a similar path to
a conventional circular parachute sized for that descent rate.
* Deployment would be from an unpacked state, as for the conventional circular
parachute in balloon use. That's pretty much a best case scenario.

It would be good to know the rules on descent rate - with a glide angle our
absolute velocity will be significantly greater than the descent rate, so we'd
need to know which it s we need to limit. Having said that, we're almost
certain to be both slower and softer than the glider they've allowed before.

Initial use on a balloon would be passive, with the steering fixed for gentle
circling. That makes it low risk with a path similar to a round parachute, and
we get to see how it deploys and performs without worrying about issues in an
active control system. I'd want to have a video camera pointing up at the
parachute to see what it did at altitude here, as it's not something we could
test easily.

For active control I'd aim to limit turn rate by limiting the range of control
input to something we know is ok if permanently applied. If the steering gets
jammed to one side it would circle down as in the passive case, and the
control system would be set to have this as its fail safe state. Being able to
aim for an unpopulated area can't really be any worse than no control can it?

These are of course the expectations without having built or tested anything -
things WILL change!

On Wednesday, 6 September 2017 21:05:45 BST 'grant gibson' via Derby Makers
wrote: