Colin Anderson Posted August 22, 2022 Share Posted August 22, 2022 A little while back, as a matter of nostalgia, I built a KK Invader. Visiting various model shows I’ve searched for a way of getting it aloft. As a kid I’d run like hell and tow my glider up; but I was never very good at it and not much better at running - I’m still not good at running! Then I heard of bungee launching and this seems to me the perfect solution. I know people use surgical tubing and it can be acquired on the internet - certainly I can’t find it at any shows - but it seems rather expensive for such a small model, such as the Invader (and in any case I prefer to see what I’m buying - especially when I’ve little idea of what I actually need. Today I was advised to use 10 metres of 1/8 silicone fuel tubing attached to fishing line. Now I would never have imagined this was possible. Is silicone fuel tubing that stretchy? I don’t want to rip my model apart! Has anyone tried it? I’d like to make doubly sure before buying such. Quote Link to comment Share on other sites More sharing options...
Shaun Walsh Posted August 22, 2022 Share Posted August 22, 2022 Not sure I'd recommend a bungee for a free flight model, it works for rc gliders because you can control the model as it goes up. I've seen a couple of gliders launched with the receiver turned off and it doesn't end well. At least with a manual tow line you get to stop running and abort if it goes pear shaped. Quote Link to comment Share on other sites More sharing options...
Colin Anderson Posted August 22, 2022 Author Share Posted August 22, 2022 Ah, thanks for that Shaun. I’m glad I asked then. Having only recently learned of the technique I’ve no idea. Quote Link to comment Share on other sites More sharing options...
John Muir Posted August 22, 2022 Share Posted August 22, 2022 https://www.youtube.com/watch?v=ZGGclmTpRwY This video has details of the bungee they're using near the start if it's any help. My father told me he used to launch his Invader single handed using a line staked to the ground and some pulleys attached to a handle. He said he just had to walk backwards to get the plane in the air. I never did figure out the details of the arrangement but maybe somebody on here knows how it works. Quote Link to comment Share on other sites More sharing options...
Colin Anderson Posted August 22, 2022 Author Share Posted August 22, 2022 Now that was illuminating, John. They seemed to go up pretty effortlessly and they were all FF. On just 1/8” flat rubber going by the captions - that ought to be readily available and I’m guessing would place less strain on a light, fragile model than fuel tubing. I’ve come across the pulley method many years ago and seen it used on full size (don’t know if it’s still used); never seen it being used for models though. Quote Link to comment Share on other sites More sharing options...
John Wagg Posted August 22, 2022 Share Posted August 22, 2022 1 hour ago, John Muir said: https://www.youtube.com/watch?v=ZGGclmTpRwY This video has details of the bungee they're using near the start if it's any help. My father told me he used to launch his Invader single handed using a line staked to the ground and some pulleys attached to a handle. He said he just had to walk backwards to get the plane in the air. I never did figure out the details of the arrangement but maybe somebody on here knows how it works. That's how we used to launch our gliders before we went onto bungees. Line attached to a stake in the ground. run line round a hand pulley and back to another pulley at the stake. Line then attached to plane using a ring and a small chute. Walk backwards and plane will accelerate at twice walking speed. If you have a helper/launcher then you don't need the second pulley as helper walks in opposite direction with hand pulley away from stake. Quote Link to comment Share on other sites More sharing options...
Colin Anderson Posted August 22, 2022 Author Share Posted August 22, 2022 Thanks John. 👍😊 Quote Link to comment Share on other sites More sharing options...
PatMc Posted August 22, 2022 Share Posted August 22, 2022 I used to use 3/16 rubber & fishing line to bungee a single channel, rudder only KK Chief. Also when there was an onshore breeze slope soared it over the local dunes. When my lad was about 7 or 8 I made an O/D FF glider a bit smaller than the Invader. I used to tow it up with a Fox 15 powered Boddo Tyro then release the glider for my son & his mate to chase after & retrieve. The Tyro was rudder, elevator control with a short dab of full down also releasing the tow line at the glider's nose via a double line arrangement. We had about 60% success getting the glider towed to a decent height & always managed a clean release even during aborted tows. The two lads thought it great fun but did get bored when the engine didn't start quickly. Quote Link to comment Share on other sites More sharing options...
PatMc Posted August 22, 2022 Share Posted August 22, 2022 The pulley tow launch method was used in some glider competitions (IIRC including F3F international events). There was a fatal accident when one of the stakes came loose during a launch & struck the tower's head. I don't know if the practice was banned in comps after that. Quote Link to comment Share on other sites More sharing options...
MikeQ Posted August 23, 2022 Share Posted August 23, 2022 (edited) Hi Colin bungee launching FF model gliders is as old as the hills. Until i irretrievably planted my RC assist KeilKraft Caprice in the top of a tree sticking out the top of a cliff i used a strip of 1/8 flat TanII rubber from a ‘spent’ mini vintage FF duration model (Dinamite) and some fishing line. Went up great. Best if there is a slight breeze to ‘kite’ into. If you are into models of that type check out hippocket aeronautics forum. There will be plenty of help there. https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=21523.0 MikeWoodhouse at FreeFlightSupplies might be worth tapping up for rubber motor off cuts if you dont have a tame FF rubber duration flier near you. I doubt you’d ever go through an entire box of ‘motor’ rubber 😀 cheers mike PS i can send you some rubber if you PM me your address. Edited August 23, 2022 by MikeQ Quote Link to comment Share on other sites More sharing options...
Colin Anderson Posted August 23, 2022 Author Share Posted August 23, 2022 (edited) Thanks, Mike. That’s very kind of you. I checked out the link you gave and have now registered to it. Looks like a very interesting and useful forum. I’m sure I ought to be able to find the rubber now I have a better idea of what to seek. Probably I can get some from someone like free flight supplies; looks like they sell 16 foot lengths for very little money - do you think that’d be long enough for the little Invader? But failing that I might take you up on your very kind offer. 👍😊 Calm wind and clear skies! 😊 Edited August 23, 2022 by Colin Anderson Quote Link to comment Share on other sites More sharing options...
MikeQ Posted August 29, 2022 Share Posted August 29, 2022 (edited) Hi Colin i tried various combinations of bungee but started with the SAM35 rules.. http://sam35.org.uk/wp-content/uploads/2018/08/glider-hi-start-rules.pdf think i went to double the rubber and 3 times the fishing line (10Ib) breaking strain ... its what i had in my fishing tackle box at the time 🙂 Ive got 1/8, 3/16 and 1/4 Super Sport from Woodhouse from dabbling in FF Mini Vintage and Open Rubber duration. Let me know if you need a length or two. mike Edited August 29, 2022 by MikeQ Quote Link to comment Share on other sites More sharing options...
Colin Anderson Posted September 14, 2022 Author Share Posted September 14, 2022 Thanks, Mike. Sorry for the late reply - notification went into my spam folder. I’ve got some flat 1/8” rubber from FF supplies. 👍😊 Quote Link to comment Share on other sites More sharing options...
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