![\"\"](\"http:\/\/www.g8srs.co.uk\/wp-content\/uploads\/2025\/01\/Picture1.jpg\")
<\/a><\/figure>\n<\/div>\n\n\n<\/p>\n\n\n
Higher still?<\/p>\n
Now as the trees I mentioned earlier were large 12-20m (40 \u2013 60 ft.)\u00a0\u00a0 So I looked for alternative ways to get the rope as high as possible.\u00a0 I considered catapults and crossbows but concluded they were unsuitable based on strength to operate and cost. My research led me to some amateur radio sites and a piece of kit called an Antenna Air Launcher. They are very popular in the US where trees are much higher than here.<\/p>\n\n\n
Air Launchers<\/span><\/h2>\n\n\nAn Air Launcher (aka Spud Gun) uses compressed air to fire a projectile into the air. Amateurs have adapted them to attach a lightweight line to the projectile. When fired over a tree a rope is attached to the line and pulled back over and fastened in a loop to be the halyard for an antenna. Dependant on the pressure applied, heights of over 30m (100ft.) can be achieved. The following figures illustrate the sequence.<\/p>\n\n
\n![\"\"](\"http:\/\/www.g8srs.co.uk\/wp-content\/uploads\/2025\/01\/Picture2.jpg\")
<\/a><\/figure>\n<\/div>\n\n\n<\/p>\n\n\n
This caught my attention and further research yielded sites to purchase one ready to use (\u00a3200 -\u00a3300) and kits to assemble (\u00a3100-\u00a3200) or in my case make yourself from published plans (\u00a350).<\/p>\n\n
\n![\"\"](\"http:\/\/www.g8srs.co.uk\/wp-content\/uploads\/2025\/01\/Picture3.jpg\")
<\/a><\/figure>\n<\/div>\n\n\nFigure 1 – Commercial Air Launcher WB6ZQZ[i]<\/strong><\/a><\/em><\/h3>\n\n\n\n
\n\n\n\n[i]<\/a> Commercial Air Launcher from Alan Biocca Engineering (WB6ZQZ)<\/p>\n\n\n\nhttps:\/\/www.antennalaunchers.com\/antlaunching.html<\/a><\/p>\n\n\n\nUK Rules and regulations<\/span><\/h2>\n\n\nIn the UK an air launcher is categorized as an air weapon.\u00a0 To keep within the law it\u00a0 must comply with the UK Firearms licensing law[i]<\/a> and Home Office Guidelines[ii]<\/a><\/p>\n[i]<\/a> Firearms licensing law\u00a0<\/p>\nhttps:\/\/assets.publishing.service.gov.uk\/media\/636a6dbf8fa8f5358665f4b9\/Firearms_guide_November_2022.pdf<\/a><\/p>\n[ii]<\/a> AIR WEAPONS:A brief guide to safety https:\/\/assets.publishing.service.gov.uk\/government\/uploads\/system\/uploads\/attachment_data\/file\/1171973\/Air_weapons_safety_leaflet_6-4.pdf<\/a><\/p>\nThe key points being:<\/p>\n
\n- Must not fire a pellet beyond a boundary of premises<\/li>\n
- Must not have an air weapon in a public place without a reasonable excuse<\/li>\n
- Must not fire an air weapon without lawful authority or excuse within 50 feet (15 metres) of the centre of a public road<\/li>\n
- Must not be used to damage property or endanger life<\/li>\n
- The air weapon muzzle velocity must not exceed 12 foot-pounds[i]<\/a><\/li>\n
- The air weapon muzzle energy must not be more than 1 joule of energy (Guns below this threshold, and qualifying \u201cairsoft\u201d guns, are not regarded as firearms)<\/li>\n<\/ul>\n
[i]<\/a>Calculations relating to a pneumatic launcher<\/p>\n\u00a0https:\/\/www.physicsforums.com\/threads\/calculations-relating-to-a-pneumatic-launcher.981365\/<\/a><\/p>\n\n\nPlans<\/span><\/h2>\n\n\nThere are many plans available on the internet and the \u00a0\u2018Build-it-yourself air cannon plans\u2019 site[i]<\/a> is a good starting point.\u00a0 However, most plans I found were based on US sizes and parts which are not readily available here. Also their standards i.e. pipe fittings and solenoid valves are not compatible with UK British Standard Pipe sizes.\u00a0 In the end I designed my own using UK and or eBay suppliers.<\/p>\n[i]<\/a> Build it yourself air cannon plans<\/p>\nhttps:\/\/aircannonplans.com\/<\/a><\/p>\n\n\n![\"\"](\"http:\/\/www.g8srs.co.uk\/wp-content\/uploads\/2025\/01\/Picture4.jpg\")
<\/a><\/figure>\n<\/div>\n\n\n<\/p>\n\n\n
With the levels of air pressure involved it\u2019s very important to use pressure rated PVC tube and adaptors than can stand high pressure. I chose 3mm wall thickness solvent weld material which would stand up to 7 bar (100 psi). The reservoir is 75mm diameter and the barrel 32mm. A Schrader air valve is used to pressure the reservoir. A \u00be\u201d BSP gas ball valve fitted with a spring release and \u00a0wired to a simple trigger. The spring speeds up the valve opening to apply instantaneous pressure on the projectile.\u00a0 The plumbing is completed with brass 3\/4\u201c BSP fittings and gas quality PTFE tape. The projectile is made using two PVC bottle stoppers to seal a short length of 25mm pipe holding a 5g weigh and a loop to attach a fishing line. The reel is held on a bracket off the barrel.<\/p>\n
CAUTION: When building pressure vessels of this type it is extremely important to follow best engineering practice. Incorrectly built these launchers can be dangerous!<\/strong><\/p>\n\n\nAssembly and Testing<\/span><\/h2>\n\n\nThe PVC pipes and adapters were assembled using solvent weld adhensive. Brass to PVC connections required PVC solvents and epoxy to make air tight joints. Joints were left to cure for 24hrs before being pressure tested.<\/p>\n
Three days before the contest and it was time to see if my home brew launcher would be a success.<\/p>\n
Using a car tyre compressor I put 20psi in the reservoir and with \u00a0100m reel of 10lbs breaking strain fishing line attached to the projectile I pointed the launcher skywards across open ground and pressed the trigger. I heard a pop (sounds like\u00a0 pulling a cork from a bottle) and watched in delight as the projectile sailed some 50ft into the air landing 150ft\u00a0 away. My delight was short lived when I saw the line had snapped at the end of the barrel.<\/p>\n
Changing to 30lbs breaking strain fishing line I repeated the test, this time the line stayed attached.\u00a0 Practice over, it was time to use it on a tree.\u00a0 I repressurized \u00a0the reservoir, aimed above the top of the chosen tree, and fired. To my relief the projectile gracefully sailed over the top towing a helical coil of line and descended to a few feet above the ground.\u00a0 I attached the end of a 50m reel of 4mm dia. rope and pulled back the fishing line. I now had a loop of rope running over a branch 12m high.<\/p>\n\n
\n![\"\"](\"http:\/\/www.g8srs.co.uk\/wp-content\/uploads\/2025\/01\/Picture5.jpg\")
<\/a><\/figure>\n<\/div>\n\n\nAntennas<\/span><\/h2>\n\n\nWith the loop in the tree I was able to hoist (and lower) my antenna.\u00a0 With this arrangement various antennas can be used e.g. end fed sloper, inverted vee, delta loop.\u00a0<\/p>\n
For the RSGB AFS contest I used 40m and 80m inverted vee half wave dipoles mounted as shown. Note the use of an additional tension rope to separate and pull the dipoles clear of the tree.<\/p>\n\n
\n![\"\"](\"http:\/\/www.g8srs.co.uk\/wp-content\/uploads\/2025\/01\/Picture6.jpg\")
<\/a><\/figure>\n<\/div>\n\n\nConclusion<\/span><\/h2>\n\n\nThis article is written solely for amateur\u00a0 radio\u00a0 interest only. The author\u00a0 provides the information in good faith and takes no responsibility for errors therein. Anyone considering building an air launcher must take full responsibility to avail themselves with good engineering knowledge and ensure safety standards are met. Compliance with the law is mandatory.<\/p>\n
My design and manufacture process was evolutionary. Selection of a suitable air valve and making the reservoir airtight took some time to get right. As did choosing and mounting the fishing line so that it does not snag in use.<\/p>\n
Finally, the dipoles worked extremely well each with an SWR of less than 1.5. In the four hours of the RSGB AFS SSB contest 250 contacts were made with some excellent 5,9+ reports and very low reception noise levels.<\/p>\n
Stay safe and keep within the law!<\/p>\n
<\/a><\/figure>\n<\/div>\n\n\n<\/p>\n\n\n
This caught my attention and further research yielded sites to purchase one ready to use (\u00a3200 -\u00a3300) and kits to assemble (\u00a3100-\u00a3200) or in my case make yourself from published plans (\u00a350).<\/p>\n\n
<\/a><\/figure>\n<\/div>\n\n\nFigure 1 – Commercial Air Launcher WB6ZQZ[i]<\/strong><\/a><\/em><\/h3>\n\n\n\n
\n\n\n\n[i]<\/a> Commercial Air Launcher from Alan Biocca Engineering (WB6ZQZ)<\/p>\n\n\n\nhttps:\/\/www.antennalaunchers.com\/antlaunching.html<\/a><\/p>\n\n\n\nUK Rules and regulations<\/span><\/h2>\n\n\nIn the UK an air launcher is categorized as an air weapon.\u00a0 To keep within the law it\u00a0 must comply with the UK Firearms licensing law[i]<\/a> and Home Office Guidelines[ii]<\/a><\/p>\n[i]<\/a> Firearms licensing law\u00a0<\/p>\nhttps:\/\/assets.publishing.service.gov.uk\/media\/636a6dbf8fa8f5358665f4b9\/Firearms_guide_November_2022.pdf<\/a><\/p>\n[ii]<\/a> AIR WEAPONS:A brief guide to safety https:\/\/assets.publishing.service.gov.uk\/government\/uploads\/system\/uploads\/attachment_data\/file\/1171973\/Air_weapons_safety_leaflet_6-4.pdf<\/a><\/p>\nThe key points being:<\/p>\n
\n- Must not fire a pellet beyond a boundary of premises<\/li>\n
- Must not have an air weapon in a public place without a reasonable excuse<\/li>\n
- Must not fire an air weapon without lawful authority or excuse within 50 feet (15 metres) of the centre of a public road<\/li>\n
- Must not be used to damage property or endanger life<\/li>\n
- The air weapon muzzle velocity must not exceed 12 foot-pounds[i]<\/a><\/li>\n
- The air weapon muzzle energy must not be more than 1 joule of energy (Guns below this threshold, and qualifying \u201cairsoft\u201d guns, are not regarded as firearms)<\/li>\n<\/ul>\n
[i]<\/a>Calculations relating to a pneumatic launcher<\/p>\n\u00a0https:\/\/www.physicsforums.com\/threads\/calculations-relating-to-a-pneumatic-launcher.981365\/<\/a><\/p>\n\n\nPlans<\/span><\/h2>\n\n\nThere are many plans available on the internet and the \u00a0\u2018Build-it-yourself air cannon plans\u2019 site[i]<\/a> is a good starting point.\u00a0 However, most plans I found were based on US sizes and parts which are not readily available here. Also their standards i.e. pipe fittings and solenoid valves are not compatible with UK British Standard Pipe sizes.\u00a0 In the end I designed my own using UK and or eBay suppliers.<\/p>\n[i]<\/a> Build it yourself air cannon plans<\/p>\nhttps:\/\/aircannonplans.com\/<\/a><\/p>\n\n\n<\/a><\/figure>\n<\/div>\n\n\n<\/p>\n\n\n
With the levels of air pressure involved it\u2019s very important to use pressure rated PVC tube and adaptors than can stand high pressure. I chose 3mm wall thickness solvent weld material which would stand up to 7 bar (100 psi). The reservoir is 75mm diameter and the barrel 32mm. A Schrader air valve is used to pressure the reservoir. A \u00be\u201d BSP gas ball valve fitted with a spring release and \u00a0wired to a simple trigger. The spring speeds up the valve opening to apply instantaneous pressure on the projectile.\u00a0 The plumbing is completed with brass 3\/4\u201c BSP fittings and gas quality PTFE tape. The projectile is made using two PVC bottle stoppers to seal a short length of 25mm pipe holding a 5g weigh and a loop to attach a fishing line. The reel is held on a bracket off the barrel.<\/p>\n
CAUTION: When building pressure vessels of this type it is extremely important to follow best engineering practice. Incorrectly built these launchers can be dangerous!<\/strong><\/p>\n\n\nAssembly and Testing<\/span><\/h2>\n\n\nThe PVC pipes and adapters were assembled using solvent weld adhensive. Brass to PVC connections required PVC solvents and epoxy to make air tight joints. Joints were left to cure for 24hrs before being pressure tested.<\/p>\n
Three days before the contest and it was time to see if my home brew launcher would be a success.<\/p>\n
Using a car tyre compressor I put 20psi in the reservoir and with \u00a0100m reel of 10lbs breaking strain fishing line attached to the projectile I pointed the launcher skywards across open ground and pressed the trigger. I heard a pop (sounds like\u00a0 pulling a cork from a bottle) and watched in delight as the projectile sailed some 50ft into the air landing 150ft\u00a0 away. My delight was short lived when I saw the line had snapped at the end of the barrel.<\/p>\n
Changing to 30lbs breaking strain fishing line I repeated the test, this time the line stayed attached.\u00a0 Practice over, it was time to use it on a tree.\u00a0 I repressurized \u00a0the reservoir, aimed above the top of the chosen tree, and fired. To my relief the projectile gracefully sailed over the top towing a helical coil of line and descended to a few feet above the ground.\u00a0 I attached the end of a 50m reel of 4mm dia. rope and pulled back the fishing line. I now had a loop of rope running over a branch 12m high.<\/p>\n\n
\n<\/a><\/figure>\n<\/div>\n\n\nAntennas<\/span><\/h2>\n\n\nWith the loop in the tree I was able to hoist (and lower) my antenna.\u00a0 With this arrangement various antennas can be used e.g. end fed sloper, inverted vee, delta loop.\u00a0<\/p>\n
For the RSGB AFS contest I used 40m and 80m inverted vee half wave dipoles mounted as shown. Note the use of an additional tension rope to separate and pull the dipoles clear of the tree.<\/p>\n\n
\n<\/a><\/figure>\n<\/div>\n\n\nConclusion<\/span><\/h2>\n\n\nThis article is written solely for amateur\u00a0 radio\u00a0 interest only. The author\u00a0 provides the information in good faith and takes no responsibility for errors therein. Anyone considering building an air launcher must take full responsibility to avail themselves with good engineering knowledge and ensure safety standards are met. Compliance with the law is mandatory.<\/p>\n
My design and manufacture process was evolutionary. Selection of a suitable air valve and making the reservoir airtight took some time to get right. As did choosing and mounting the fishing line so that it does not snag in use.<\/p>\n
Finally, the dipoles worked extremely well each with an SWR of less than 1.5. In the four hours of the RSGB AFS SSB contest 250 contacts were made with some excellent 5,9+ reports and very low reception noise levels.<\/p>\n
Stay safe and keep within the law!<\/p>\n
https:\/\/www.antennalaunchers.com\/antlaunching.html<\/a><\/p>\n\n\n\n In the UK an air launcher is categorized as an air weapon.\u00a0 To keep within the law it\u00a0 must comply with the UK Firearms licensing law[i]<\/a> and Home Office Guidelines[ii]<\/a><\/p>\n [i]<\/a> Firearms licensing law\u00a0<\/p>\n https:\/\/assets.publishing.service.gov.uk\/media\/636a6dbf8fa8f5358665f4b9\/Firearms_guide_November_2022.pdf<\/a><\/p>\n [ii]<\/a> AIR WEAPONS:A brief guide to safety https:\/\/assets.publishing.service.gov.uk\/government\/uploads\/system\/uploads\/attachment_data\/file\/1171973\/Air_weapons_safety_leaflet_6-4.pdf<\/a><\/p>\n The key points being:<\/p>\n [i]<\/a>Calculations relating to a pneumatic launcher<\/p>\n \u00a0https:\/\/www.physicsforums.com\/threads\/calculations-relating-to-a-pneumatic-launcher.981365\/<\/a><\/p>\n\n\n There are many plans available on the internet and the \u00a0\u2018Build-it-yourself air cannon plans\u2019 site[i]<\/a> is a good starting point.\u00a0 However, most plans I found were based on US sizes and parts which are not readily available here. Also their standards i.e. pipe fittings and solenoid valves are not compatible with UK British Standard Pipe sizes.\u00a0 In the end I designed my own using UK and or eBay suppliers.<\/p>\n [i]<\/a> Build it yourself air cannon plans<\/p>\n https:\/\/aircannonplans.com\/<\/a><\/p>\n\n <\/p>\n\n\n With the levels of air pressure involved it\u2019s very important to use pressure rated PVC tube and adaptors than can stand high pressure. I chose 3mm wall thickness solvent weld material which would stand up to 7 bar (100 psi). The reservoir is 75mm diameter and the barrel 32mm. A Schrader air valve is used to pressure the reservoir. A \u00be\u201d BSP gas ball valve fitted with a spring release and \u00a0wired to a simple trigger. The spring speeds up the valve opening to apply instantaneous pressure on the projectile.\u00a0 The plumbing is completed with brass 3\/4\u201c BSP fittings and gas quality PTFE tape. The projectile is made using two PVC bottle stoppers to seal a short length of 25mm pipe holding a 5g weigh and a loop to attach a fishing line. The reel is held on a bracket off the barrel.<\/p>\n CAUTION: When building pressure vessels of this type it is extremely important to follow best engineering practice. Incorrectly built these launchers can be dangerous!<\/strong><\/p>\n\n\n The PVC pipes and adapters were assembled using solvent weld adhensive. Brass to PVC connections required PVC solvents and epoxy to make air tight joints. Joints were left to cure for 24hrs before being pressure tested.<\/p>\n Three days before the contest and it was time to see if my home brew launcher would be a success.<\/p>\n Using a car tyre compressor I put 20psi in the reservoir and with \u00a0100m reel of 10lbs breaking strain fishing line attached to the projectile I pointed the launcher skywards across open ground and pressed the trigger. I heard a pop (sounds like\u00a0 pulling a cork from a bottle) and watched in delight as the projectile sailed some 50ft into the air landing 150ft\u00a0 away. My delight was short lived when I saw the line had snapped at the end of the barrel.<\/p>\n Changing to 30lbs breaking strain fishing line I repeated the test, this time the line stayed attached.\u00a0 Practice over, it was time to use it on a tree.\u00a0 I repressurized \u00a0the reservoir, aimed above the top of the chosen tree, and fired. To my relief the projectile gracefully sailed over the top towing a helical coil of line and descended to a few feet above the ground.\u00a0 I attached the end of a 50m reel of 4mm dia. rope and pulled back the fishing line. I now had a loop of rope running over a branch 12m high.<\/p>\n\n With the loop in the tree I was able to hoist (and lower) my antenna.\u00a0 With this arrangement various antennas can be used e.g. end fed sloper, inverted vee, delta loop.\u00a0<\/p>\n For the RSGB AFS contest I used 40m and 80m inverted vee half wave dipoles mounted as shown. Note the use of an additional tension rope to separate and pull the dipoles clear of the tree.<\/p>\n\n This article is written solely for amateur\u00a0 radio\u00a0 interest only. The author\u00a0 provides the information in good faith and takes no responsibility for errors therein. Anyone considering building an air launcher must take full responsibility to avail themselves with good engineering knowledge and ensure safety standards are met. Compliance with the law is mandatory.<\/p>\n My design and manufacture process was evolutionary. Selection of a suitable air valve and making the reservoir airtight took some time to get right. As did choosing and mounting the fishing line so that it does not snag in use.<\/p>\n Finally, the dipoles worked extremely well each with an SWR of less than 1.5. In the four hours of the RSGB AFS SSB contest 250 contacts were made with some excellent 5,9+ reports and very low reception noise levels.<\/p>\n Stay safe and keep within the law!<\/p>\nUK Rules and regulations<\/span><\/h2>\n\n\n
\n
Plans<\/span><\/h2>\n\n\n
<\/a><\/figure>\n<\/div>\n\n\nAssembly and Testing<\/span><\/h2>\n\n\n
<\/a><\/figure>\n<\/div>\n\n\nAntennas<\/span><\/h2>\n\n\n
<\/a><\/figure>\n<\/div>\n\n\nConclusion<\/span><\/h2>\n\n\n