Comment by Rory Paul on April 27, 2009 at 12:23pm

I heard that a transponder solution costing no more than $150 a unit, small enough to be flown on RC size aircraft was proposed and rejected as too costly by AOPA. They did not like the idea of forcing their members flying $500K planes to fork out $100.

Moderator Comment by Gary Mortimer on April 27, 2009 at 12:55pm

Well trouble is that transponder does not exist. At least to my knowledge, I just had my portable Mode S one for work serviced and that cost a cool £3000, about $4.50 at the current exchange rate.

Its also a little big for our use.

But for a bigger drone I would have thought it a must.

Amazed they dont have them already, and dont they have radio repeaters so that the pilot can operate just like a real pilot with voice comms to ATC on them there Predators??

I think the key for our game is weight, sub 7Kg and no flights outside of line of sight.

If you think its going to get better than that in the near future then you had better be sent to stores for a long wait.

Other than sense and avoid, the other phrase you need to think about is that for larger UAV's authorities will require aircraft safety standards better than or equal to current manned flight rules.

Cheap chinese servos and brushless motors might not cut the mustard!!

All that said, I am sure Predators and my own personal fav, the Scaneagle, which has just completed more than 150,000 hours in service are more than upto the job.

Not getting a fleet of them over task is just plain silly.

Maybe the pilots could have used a thing called a phone and coordinated with each others levels they might use. All of us above 10,000 Navy you do 12000, Army you do 14000, Airforce 16000.

I bet those service guys were hacked off!

Comment by Paul Mace on April 27, 2009 at 12:56pm

You assume AOPA+GA Mfgrs.+FAA simply want to solve the problem. ADS-B is arguably less technically complex than Ardupilot. But airspace regulation and control is a $mega-billion industry with a stunning diversity of stakeholders. They thrive upon controversy and delay. The perfect, here, is the archenemy of the possible, and each stakeholder clings to their view of perfection.

Comment by Marc Ramsey on April 27, 2009 at 2:33pm

Here is what Condor is referring to:

http://www.mitre.org/work/tech_papers/tech_papers_08/07_0634/

This ADS-B UAT transmitter is constructed using $150 US worth of cellphone RF components (the frequency bands are adjacent), I believe the prototypes run for 12 hours on 4 AA batteries and can be received by other aircraft and ground stations upwards of 100 miles away. Estimated price of a production device is well under $1000 US. They've since come up with a similar transceiver design that could sell for under $1200. AOPA, EAA, SSA would all love have such a device, the problem is that the FAA proposed regulations for ADS-B will not permit devices such as this to be certified, instead they are fixated on IFR solutions which presently cost upwards of $10000 to purchase and install, require several large boxes (including an IFR certified GPS unit), need a significant amount of power, plus they are still planning on requiring a Mode C transponder ($3000 to $5000 installed).

Comment by Mike Bakula on April 28, 2009 at 10:52pm

Um, I think he discussion so far is mistaking the problem. Whle there is some concern that a passenger jet could run into a UAV and have a problem, it's far more likely that a UAV will run into a private plane that doesn't have a transponder or radio. (FAA-speak for this situation is "non-cooperative aircraft".) Any system asking to be certified would have to demonstrate that it could sense and avoid 'ol Bob out for a VFR flight in his Fly-Baby).

Bob's not required to have any kind of radio on board, if he's not flying into controlled airspace (he doesn't, he hates talking to towers), and since the Fly-Baby doesn't have an electrical system, there's no lights or transponder either. The plane's mostly wood, so it doesn't give much of a primary return on radar.

That's the problem the FAA is posing.

Comment by Marc Ramsey on April 29, 2009 at 12:10am

As a glider pilot who flies in the Reno, Nevada area, I'm acutely aware of this problem. We operate at up to 18000 feet (and in certain designated areas, even higher), and due to the lack of an engine-driven electrical system, we are not required to have transponders. Near-misses with airliners and general aviation aircraft approaching or departing Reno are not uncommon, as a result many (but not all of us) have voluntarily equipped with Mode C transponders (primarily to trigger TCAS in larger aircraft). Three years ago there was a collision at 14000 feet, 40 miles out from Reno between a business jet on approach and a glider with a non-operating transponder. The jet crash landed at a small airport nearby, the glider pilot had to use his chute, luckily no one was hurt. Our big worry is that next time it might be, say, a 767, and we won't be quite that lucky.

In reality, the pilots of airliners and IFR GA aircraft are pretty much heads down during the approach and departure phases of flight. Gliders are nearly impossible to see even from a short distance, unless you know precisely where to look. An airliner climbing directly towards you is almost impossible to pick out against the ground clutter. An airliner descending from above and behind at 250 knots will usually be heard before it is seen (and believe me, just hearing the sound is enough to ruin your day).

In other words, "see and avoid" is not working in this situation, and there are many other such situations around the country (not all involving gliders). We are pretty much equivalent to UAVs in that sense. Mode C transponders are not well suited to glider installation, due to size, weight, and power consumption. Small, low cost, low power UAT devices, in conjunction with a fully deployed ADS-B system, would make it possible for gliders, paragliders, hang gliders, skydivers, light sport aircraft, Bob in his Fly-Baby, and even UAVs, to safely integrate with each other and IFR aircraft in increasingly congested Class E and G airspace.

The real problem is that the FAA is dragging its feet on ADS-B, particularly in the VFR realm, mostly because the radar folks still call a lot of the shots...

Comment by Mike Bakula on April 29, 2009 at 11:25am

That's true. But (short of a catastrophe that could have been avoided by universal transponder usage,) FAA isn't going to give up on the sense and avoid concept. So it's up to us to figure out how to see Bob, gliders and other non-cooperative traffic.

Since we're generally into small systems, ground-based observation is probably easiest to start with. Optical sensing is probably feasible, but target discrimination is not easy. Maybe a scanning thermal sensor? Most aircraft (even gliders) can be discriminated by temperature.

Comment by Paul Mace on April 29, 2009 at 11:49am

RF advantage is transparency to weather and to host aircraft [when antenna properly positioned]. Solution may incorporate other sensors [while obtaining 3D view adds cost and complexity] but must include at least passive RF. [Fly-Baby Bob emits lots of RF in the magneto range]. Assume turbine aircraft never actually ever "see and avoid" smaller aircraft outside Bravo and Charley airspace;they rely on ATC traffic alerts, transponder/TCAS and BigSky Theory. How do we make smaller aircraft always avoid flying RF sources--with optics and thermal for last-ditch, close-in, do or die maneuver ?

Comment by Paul Mace on April 29, 2009 at 11:54am

...and yes, let's not forget doppler/sound signatures, which could be very effective--at anything less than transonic airspeeds.

Comment by Stephen Carlson on September 28, 2009 at 11:16am

I had been thinking about the sense and avoid issue, and I had settled on the idea of passive transponder "ping" detection around the 1060Mhz range where they operate. But recently, I've had the idea of just listening for aircraft just like birds do. Sounds impossible as the UAVs motor has to be turned off to hear anything, right? What if a micro-controller could filter or cancel out the noise from the motor on the UAV? Then listening for the airplane would presumably be easy, right? Have two or three mics, one specifically to pick up the noise from the motor, perhaps mounted to the motor. The other two mics would be placed on opposite sides of the aircraft as far apart as possible. This would be for further noise cancellation and for direction determination of the threatening/approaching airplane.

-Steve

Comment

• ‹ Previous
• 1
• 2
• Next ›
• Page