In AirborneWindEnergy forum, Robert Copcutt wrote:
> . ... I think it is reasonable that tethered craft look out for
untethered craft and make sure they get out of the way. ... >
"Sense & Avoid" is a basic pending sUAS
requirement sure to prevail for many years. Pending state-of-the-art
requires a human VO (visual observer) who will also use hearing to early
detect local air traffic. Automated Sense & Avoid systems cannot soon
compete with the human eye/ear/brain. Aviation ATC/transponder
capability is only a partially open network, but the system is to be
overhauled for NextGen.
Ground based radar will probably prove the
ideal method for Sense & Avoid. It can serve double duty of monitoring a
kite array and local air traffic. GPS on every kite does not have this
double function and is subject to jamming, power loss, and other
failure-modes. Radar will also operate in fog and at night better than
human senses. Development of a radar-based AWE tool is an attractive
Once a sensed event elevates to a hazard,
the avoid function is fastest and easiest by use of "kite-killers," with
soft kite elements able to fall harmlessly to earth in an incident.
~Dave Santos April
Comment and development of this topic will be occurring here.
All, send notes, drawings, and photographs!
Terms and aspects:
Commentary is welcome:
- There may develop an aviation environment that is more loaded with
tethered systems than with untethered systems. Aerial cableways.
Free-flight tethered AWECS. Aerial homesteading. Massive tethered kite
energy systems performing a myriad of tasks. Cost of avoidance of
collision for untethered craft might be miniscule compared to the cost
of avoidance performed by tethered systems. Efficient skies and waters
might respect the net costs as rules and decisions are made. There maybe
tethered systems that take a year or more to deploy with design intent
never to be absolutely decommissioned, only maintained; such might
transport people and goods around the world by windpower; a single-place
ultralight could know where that tethered system is and avoid collision;
the tethered system would be seen by other aircraft and watercraft
through a variety of systems for redundancy. One does not move the
Empire State Building to get out of the way of any other user of the
airspace. ~ JoeF
- Joe, Good point but let's take the first
steps first. The job of the aviation
authorities is to protect people and they do it very rigorously because
mishaps are extremely newsworthy and threaten the whole aviation
industry. Newcomers like AWE need to prove they have an important need
and cause no extra danger. Promising to make every effort get out of the
way will smooth the negotiating path. And why not? It is possible.
Tackling the issues of your more ambitious proposals need to come later.
- Dave S,
A combination of ground based radar, infra red cameras and microphones
would detect aircraft before any human, and pinpoint their position and
trajectory more accurately. One observation station could serve for many
AWE systems in a cluster or farm.
I agree GPS will have limited use. However, it is interesting to compare
that technology with what AWE needs to achieve. A GPS unit needs to scan
for suitable satellites and then measure incredibly accurately how long
the signals take to arrive from each. It then needs to do very complex
calculations to work out its position based on that of the satellites.
It then overlays that information onto a detailed map. To think that all
that functionality can be put into a tiny unit that costs a few hours
wages is to me a major reassurance that AWE can be automated.
Kite position can be determined with simpler sensors with faster
responses. For instance the sensors from a humble computer mouse could
determine exactly how far the tethers have been released. Other sensors
would measure the angle of the tether leaving the reel. More would
measure the tension in the tethers. That information together should
locate the kite better than GPS, and more quickly. GPS and video can be
used to confirm the primary measurements and detect faults.
Rather than letting kite elements fall to the ground where they are
likely to be damaged would it not be better to reel them into a
protective docking station.