from Hacker News

Pneumatic Antenna Launching Systems

by pubby on 6/4/23, 7:58 PM with 23 comments

  • by gorgoiler on 6/5/23, 10:30 AM

    I’ve always loved the topography of friction savers / cambium savers:

    https://m.youtube.com/watch?v=sKEfLm066-4

    It’s such a clever idea using the emergent properties of gravity, stiction, and geometry.

    A friction saver is a thick strap with two eyelets in it. With the strap placed over a limb, you can then run a thick rope through the eyelets instead of running the rope over the limb, which would otherwise abrade the rope and tree surface.

    But how do you get the friction saver up there in the first place? To install, once you have a throw line over a limb you then add the friction saver as a segment to the end of the throw line but with the throw line also threaded into the eyelets of the friction saver. Once the friction saver is over the limb it will stick with a sticktion much stronger than the throw line is stuck to the friction saver.

    Getting it back down is another clever trick which relies on one of the eyelets being larger than the other. To understand that (er, or indeed the whole system, as this is quite hard to explain) … watch the video.

  • by 1letterunixname on 6/5/23, 6:22 AM

    There's no diagram or visual of what the heck it was for.

    Apparently, it launches a lead line over a high tree branch on the end of a tennis ball to hoist up wire for an antenna. PVC potato gun in Stinger form-factor.

    I'm curious why they didn't use fishing line considering it's much lighter.

  • by tyingq on 6/5/23, 12:39 PM

    That's pretty interesting. I used normal long wire antennas, anchored to a mobile tower that was pretty fast to erect in the military. I'm somewhat surprised a launcher like this wasn't an existing option. Maybe it is for the highly mobile, "first in" type comm+other units (like ROMADs in the USAF)?

  • by voxadam on 6/5/23, 7:53 AM

    My ham father built and uses one functionally similar to this one. It's slightly more involved than using a wrist-rocket/slingshot but it's also far more effective at reaching high branches.

  • by yardie on 6/5/23, 1:30 PM

    Be careful using PVC with compressed air.[0] It can shatter into hundreds of tiny daggers flying through the air.

    [0] https://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-...

  • by resters on 6/5/23, 2:47 PM

    For anyone who is interested in amateur radio but hasn't had much experience yet, please note that getting some wire high up into a tree is a great way to make HF operation more fun especially when running a low power transmitter.

  • by aaron695 on 6/5/23, 12:02 PM

    This is circa 2003. (2006 archive- http://web.archive.org/web/20060619223222/https://antennalau... )

    That's close to pre-internet society.

    As others point out, the tech and consensus is way different now.

    Cheap throw bags on eBay or Aliexpress for instance, no need for sinkers - https://www.aliexpress.com/w/wholesale-throw-bag-Arborist.ht...

    The world of confiscated Monkey's Fist's at ports is an interesting one - https://www.portskillsandsafety.co.uk/news/confiscated-monke... You can add it to your dangerous knots list.