Land on the net, or crash?

[red_gol]

We tested different "net landing" on the past weekend.

We installed a 6x6 meters net on Saturday. From the video, you can see it works ok for small size planes. We tested both e-powered foam plane and a 40 size trainer. They are light so they can hang on the net. But our twin boom pusher UAV is a 15kg big one, the landing gear may be broken on such net.

So, on Sunday, we made a new "net" ourselves. It actually has vertical ropes only. And the UAV's fuselage can pass the net without hurting the landing gear, and the vertical ropes will stop the wings. We got this idea from watch a video of an Israeli UAV.

We used a 40 class trainer to test this one. We used very strong force to make the upper horizontal straight, so that the vertical ropes can be stretched. But you can see from the video, the horizontal rope was broken by small force. It will never work for a big UAV.

We are seeking for better desgins.

Test Video 01 (http://www.youtube.com/watch?v=XIAqwCjL-Jg)

Test Video 02 (http://www.youtube.com/watch?v=McWnEKkHQOU)

Test Video 03 (http://www.youtube.com/watch?v=rVX4DFRxh3g)

[Michael_UAV]

The vertical line net has been around for a very long time, mainly with the aircraft from IAI (read Pioneer UAV shipboard recovery). It's a good design and helps to mitigate any risk to the aircraft when "slamming" into the net, however violent it may appear.

Good work. Keep it up.

[pitviper51]

i can see this as useful on a slope.. but for a power plane .. it shows lack of flying skill when not being able to land.. or takeoffs are optional landing are manditory wouldnt be a valid phrase... cool way to retire a net tho haha
mike

[infopimp]

Why not try adding a lower line... anchor one or more fishing reels in the ground in front of the net... attach mono line from the reel(s) to the lower net line.

As the plane hits and the lower line is drawn out, it would slow the net down and dampen the oscillation, giving a wider "slowdown band" and reducing snap back.

The nice thing about the fishing reel idea is that they are available, cheap, and with their bail mechanism you can "dial in" different drag for different planes... maybe some planes don't need as many reels attached to the net, or any at all.

//armchair Quarterback with no motivation to try this, but you asked... so theres my idea

[Unterhausen]

my idea is to approach the net just a little faster than stall speed. But that's because I don't have an unlimited amount of money.

[clolson]

i can see this as useful on a slope.. but for a power plane .. it shows lack of flying skill when not being able to land.. or takeoffs are optional landing are manditory wouldnt be a valid phrase... cool way to retire a net tho haha
mike

I'm just guessing, but I think the point of the net over the ground is to work out the kinks in the process before trying to go out on a ship or some other environment where a traditional landing is not possible. Just a guess ... I do usually get in trouble though when I try to think and make assumptions. :-)

Curt.

[Unterhausen]

seems like a lot of people want to use nets, landing is the hardest part of flying. Then you can use untrained pilots. Of course, then you need to design for crash loads.

[clolson]

seems like a lot of people want to use nets, landing is the hardest part of flying. Then you can use untrained pilots. Of course, then you need to design for crash loads.

Now that you mention it, I have noticed that the first question I always get when doing a demo is "can it take off and land by itself?"

People seem to want (or almost expect) a room full of autonomous aircraft that fuel themselves up, maintain themselves, taxi out to the take off point by themselves, take off, fly, land by themselves, process all the data by themselves, put themselves away in the hanger by themselves, etc. etc. We should only need one part time person to run a fleet of 100 UAV's that are in the air full time, right? :-)

Curt.

[Unterhausen]

I asked one of our robotics guys what application he could think of that involved UAV's. Basically, he wanted the planes to be completely autonomous, including refueling. His robots can't do that. Of course, it isn't outlandish to expect a plane to land itself, but autonomous refueling is R2D2 stuff. But my understanding is that fielded autonomous systems are rare to nonexistent, fielded systems are pretty much all teleoperated.


Now that you mention it, I have noticed that the first question I always get when doing a demo is "can it take off and land by itself?"

People seem to want (or almost expect) a room full of autonomous aircraft that fuel themselves up, maintain themselves, taxi out to the take off point by themselves, take off, fly, land by themselves, process all the data by themselves, put themselves away in the hanger by themselves, etc. etc. We should only need one part time person to run a fleet of 100 UAV's that are in the air full time, right? :-)

Curt.

[toxicmouse]

ScanEagle has a pretty good recovery device, not quite a net- more of a vertical rope.

has anyone ever tried parachutes?

[CDN-uavpilot]

There is a company specializing in aircraft arresting systems. For their net system, see the link

http://esco.zodiac.com/index.cfm/navid-101

[Unterhausen]

I thought about parachutes, but that is a lot of weight. I saw an analysis that showed you need a very heavy parachute to get your plane down at a reasonable speed.

I was just thinking about this problem, and came up with a unique solution. The Stevens Aero SQuiRT is known for it's flat spin landings. http://www.stevensaero.com/download/video/squirt400_0001.wmv
Doesn't take much space, but I don't know how easy it would be to convince the autopilot to do that.