# Are there standard ground-tether systems for unpowered aircraft?

Do grounding systems have any standards or conventions? Is tethering specified in any way?

I can understand the engineering aspects of the question, but I am wondering about regulation or convention.

.....I have a suspicion that any kind of formal or experimental craft / flyer is probably not regulated, so long as it doesn't 'escape' and remain in the air while it drifts into a controlled airspace.

1. I've participated in many balloon flights, and have never seen anything specific with this, so I suspect the answer is too simple ('no') or that this question is otherwise not well formatted
2. this question may be too close to the history of experimental-craft
3. I would appreciate help with proposing tags for this question
• Would it even qualify as an aircraft if still tethered? Sounds like you're describing a kite. :) Dec 19, 2013 at 8:37
• I am mostly thinking about balloon-craft — but I am also thinking about kites and other tethers systems that incorporate glider / wing / sail. Dec 19, 2013 at 14:12
• Not sure if it qualifies as an "aircraft", but I know in the US the FAA regulates tethered balloons and such, so I'll post an answer in that vein. Maybe the answer will help you with tagging ideas... Dec 26, 2013 at 7:23

In the United States moored balloons (or kites) are governed under Part 101 of the FARs (a much neglected and very short corner of the regulations that also covers amateur rocketry and "unmanned free balloons" -- looking at your profile it's probably a section you'd find very interesting!).

In this particular case you're probably looking for Subpart B - Moored Balloons and Kites.

The FAA is mum on the specific engineering requirements of mooring systems - I expect they anticipate you will work with structural and mechanical engineers to design a tethering system that can safely hold the loads your moored object will place on it (or just tie it to the biggest, most structurally secure thing you can find, with a nice heavy rope and a proper knot).

There are a few things they ARE pretty specific about though.

• Some operating limitations (altitude, size, location, visibility).
• The fact that you have to tell them about it in advance
(At least if it's more than 150 feet AGL, per 14CFR101.15)
• Lighting and marking requirements for the tether(s)
(14CFR101.17, which basically says the mooring line must have pennants (daytime) and/or lights (nighttime) to ensure visibility)
• What happens to Balloons if the tether breaks
(14CFR101.19, which basically says if the balloon breaks free of its moorings you need a "rapid deflation device" that gets it down in a hurry so it's not just wandering around up there).

Interestingly they don't seem to care so much if a kite escapes its moorings.

• Really great sussing that out, particularly FAR pt. 101 . Dec 26, 2013 at 12:46
• @TheWhiteDiamond Its a section I'm pretty familiar with because I used to coordinate rocket launches. Dec 26, 2013 at 17:35
• If kite breaks loose, drag quickly accelerates it to wind speed, but then it's not producing any lift and quickly falls to the ground. So they don't need to care, because kite is not flying anywhere for simple physical reasons. (And if you fly it so close to something that it falls on it and damages it, you are liable from civil law anyway and additional regulation is not needed.) Jun 20, 2014 at 18:40
• @JanHudec "not flying anywhere" is a pretty relative statement: I've seen kites break loose from strings gain quite a bit of altitude (and travel a substantial distance) before they come back down. I could easily see one flying in a park near an airport winding up in the approach/departure path on a breezy day, it's just likely to not stay there very long for the reasons you describe. (In other words this is more airspace management by the "Big Sky Theory" - it's unlikely to collide so it gets ignored.) Jun 20, 2014 at 18:46

Tethering for balloons is largely left up to the manufacturer. Most have specific requirements / recommendations in the aircraft manual.

Most pilots and manufacturers will recommend a 'three-point' tie-off system. This system connects three ropes from the top of the balloon to the up-rights on the basket and then attaches a secondary rope to each of those which is tied to a car or truck. This provides a stable tethering system that 'holds' the envelope in place is very robust.

Manufactures normally also allow three ropes to be connected to the uprights only but if it gets windy this can be very hard on the system. I looked around for the PDF version of my manual but am having a hard time finding it; its even got illustrations.