|Tosh McCaber||12/08/2020 12:44:33|
|192 forum posts|
My old 1/4 dia bungee surgical rubber tubing finally perished after many years of (ab)use. So, after a lot of fruitless looking, I bought 30m of rubber tubing from China (advertised as 30m- but it came in 3 10m lengths, which I joined together) about 11/2 years ago.
Haven't used for the past 9 months- to find now that the exposed outer windings round the reel have completly perished and hardened! Even though it's been lieing in a dimly lit room.
Does anyone know of a source for good quality latex bungee rubber?
|robert chamberlain||14/08/2020 01:27:16|
|160 forum posts|
Tosh, I got mine at a medical supple house.
I am interested to know just how big a model ( weight/ wingspan) you could launch with the 1/4 inch tubing? I was just gifted a reel of 25 feet and 100 feet of string. Here in the "fly over states" the only option is to go electric launch.
|Tosh McCaber||14/08/2020 07:35:20|
|192 forum posts|
For the many years that I used my old 1/4" rubber, I recall that it was used on anything up to 120" wingspan- quite powerful.
|Tosh McCaber||14/08/2020 07:36:02|
|192 forum posts|
Just wondered if anyone has purchased any recently?
|191 forum posts||
Tosh, I suspect the answer to that is, no. Using a Hi-Start is a niche interest rarely discussed on this forum. When I came to model aircraft a couple of years ago with a high start launched balsa glider I was met at the field with incredulity.
In the absence of suitable lengths of latex tubing I made my first Hi-Start with silicon rubber tubing bought from HobbyKing. It was far too viscious for my light weight 'plane, more of a catapult than a smooth pull skyward. I found something I think came from Graupner, a sort of thread covered elastic that was intended for models up to 500g weight. I still use this.
The supplier of choice for the 'money no object', off the shelf solution was emc-vega in Germany. They have a range of products.
|3031 forum posts|
My old glider and silent flight only club in the 1980s used to struggle to get decent surgical rubber for bungees even back then, and it was often the case that what we bought from various suppliers at a big expense differed greatly in performance and durability. When we did source an example that was of the required quality it would quite quickly degrade in performance and begin to deteriorate over only a few months' use despite TLC with storage. What I assume was natural latex rubber was the only stuff to get and as such it didn't last long, whether used regularly or not. It would start out as a nice light straw colour but would soon darken to brown as it aged and hardened. I'm sure Dick Edmonds secured a supply of good stuff for a while, but eventually even that dried up. We did use tow lines, but as we got older and lazier - no young members to press into running a line either - electric winches were used for a while but they also had their problems but I'd moved over to power flying by then.
Dogs chewing the rubber didn't help either when it was laid out, but on public land there wasn't much we could do about that - still a potential problem now if you fly in a park. The black, so called 'silicon rubber' tube was hopeless and of course the cotton covered multi-stranded stuff was also quite useless. It's not just in the initial stages that a good height is gained, but with decent rubber the surgical bungee can be re-stretched using the wind (often having the model go behind your launch point) by tacking left and right but not so much that you get greedy and ping off or start to sink. With practice and in favourable conditions I had some huge launch heights using this technique - very satisfying!
Tosh M.......Considering how efficient, inexpensive and convenient electric systems are for gliders of all sizes and needs, I can't fathom why the old Hi-start would be of interest these days. A bit like going back to a starting handle for your car? I doubt if suitable rubber is available now anyway. The emc-vega stuff looks interesting but it's expensive, looks to be very dark in colour and without actually testing an example I'd be reluctant to spend out on it.
Self launching may well even open up smaller flying areas that would be quite unsuitable for a line and rubber where the risk of getting caught on trees or fences might be a problem if the wind shifts.
Best of luck, will get back to some pure (electric launch) silent flying in the future myself.
Edited By Cuban8 on 14/08/2020 10:36:26
|Martin Harris||14/08/2020 10:47:01|
9497 forum posts
Regarding storage, I seem to recall stories of full size glider bungees (Y shaped cotton covered rubber shock cords pulled by 3 or 4 people on each "arm" being stored under water to avoid degredation.
We did have one at our gliding club which was just stored in a dark but dry room - I have no idea how old it was - which we got out one very low cloud day and took turns launching and briefly hopping a Grunau Baby from a small ridge on the airfield. It seemed quite effective after what must have been an extended storage period.
We've got an old cotton covered bungee at our model flying club - at least 20 years old to my knowledge and may be considerably older - which was still serviceable last time it emerged from its cupboard 3 or 4 years ago.
Edited By Martin Harris on 14/08/2020 10:48:28
|Tosh McCaber||14/08/2020 10:51:43|
|192 forum posts|
Thanks for your opinion, Cuban. Sorry- I disagree. I'm not going to electrify my squadron of older- (even newer)- gliders, probably not practical. I'm not only going to use them on the slope- some are flat field anyway.
I sometimes take a glider with me when we go on holiday (hmm- remember holidays??) Not every club has an electric winch. Our club actually has "Soarers" in its logo! And the electric winch ain't always available.
I may have to revert to more Chinese "rubber"! Unless anyone has any leads?
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