Towline material?

[Anonymous]

Next season, I intend to upgrade to a bunter fron normal zoom models. Currently using Klaus Salzer towline, but I’m wondering if there is something more easily available that will handle a mid-performance F1A bunter? Thanks in advance.

[OLIVER CAI]

Hi Hueydriver,

I usually use a 200lb test Kevlar towline. Usually kevlar towlines are for high performance F1A’s and F1H’s. You can buy a 50 meters of kevlar for $11 or 1000 ft for $55 from Jim Bradley. His website is http://www.members.aol.com/bmp4carbon/
and you can email him at bmp4carbon@aol.com.

[Anonymous]

I have used the Bradley Kevlar 200 lb, 120 feet with 40+ feet of yellow 80 lb. monofilament, .038 inches or a little under a millimeter in diameter. Don’t like the knot at the junction, but it works for high performance bunters.

I have also used clear polyester line from M/K. 164 feet of one material.

I am going to do some stretch tests with the full line of Bradley yellow 80 lb monofilament vs the polyester. See which gives me the most stretch.

The pull test is 5 kilograms, but the models pull about 20 kilograms in flight, so you can get a lot of stretch out of the line, and maybe an extra meter at launch. The stretchy materials also release a lot more energy at release. But you don’t want the line to take a permanent set after each launch so that you have to keep shortening the line to make the 164feet and 5 kilogram pull test.

So it should be fun to compare the monofilament against the polyester.

With all of these lines, you really need a larger diameter reel than is currently available.

I was setting up a brand new line at the US team trials when someone well known ran their motor bike right over my line and got it all tangled in their chain. This was right through the pull test /line checking area. Needless to say that line was instant junk.

[Anonymous]

Huey—

I different point of view from Dave.

The high performance bunters are using low stretch line. Low stretch line converts more of the Pull Down” energy into velocity– ie higher launches. It also makes for more consitant launches because the zoom rudder and other launch time related actions happens more directly to the flyer’s input.

Flyers have used solid steel line but this has not become popular due to the saftey and lack of practicality.

The most practical is the Russina Rod. M&K (I can help if you want some) and Victor Stamov (Brian VanNest can help). This line stretches about 8 inches at 5 kg.

I use 150lb spectra with a 30 foot monofilment leader. There are many spectra lines in the fishing and kite sports. I’m continually trying new brands. For windy weather I use a “soft” 150 lb american monofiliment. Stretches about 16 inched at 5 kg. For calm, I use the M&K as a leader- stretch is about 4 inches. I have found it best to use a small ring (1/4 inch- single piece– fishing shops) to attach the spectra to monofiliment line.

I have stretch numbers at 40 lbs but don’t know them off the top of my head.

I like a bit of stretch in wind and thermals to prevent premature unlatch- I will lilely change to low stretch leader line as I get more comfortable with my eHook.

My son, like many eastern flyers, uses Spectra with a 3/32 or 1/8 nylon-dacron line. Does not coil and tangle as the monofiliments do.

A couple of flyers use all spectra line but wear gloves to prevent line cuts.

Probably more than what you wanted to hear. Kevlar works– the 80 lb mono is too stretchy for my liking but could work OK for moderate launches.

Jim Parker

[Anonymous]

Thanks all. The Russian Rod…what type of material is it? I’m looking to fly a windy weather zoom model and one mid performance bunter for calmer weather so will have two winches at all times. From what I read above, the 80 lb mono would be good for the zoom model and the russian rod or kevlar combo good for the bunter? Remembering I’m relatively new to F1A and that flying (flight control) ability would be favored over performance.

[Anonymous]

I just made up 2 new lines today.

#1 M&K 1mm, 040″ diameter polyester

#2 Jim Bradley .038 diameter monofilament, yellow in color

The Russian rod I think someone referred to is the .040 polyester.

At 11 lbs pull the polyester stretches 8″, the monofilament 5 feet.
So a monofilament line would have to be set up at 159 feet to meet the 5 kilogram pull test, and the polyester, 163′ 4″.

At 25 lbs pull, the mono stretches 10 – 12 feet and takes a permanent set of maybe 4″ with each pull. The polyester stretches about 12 inches and does not take a set.

So if you wanted to get the most stretch, you could get an additional 5 to 7 feet over the allotted 164 with the monofilament.

To be legal, you would have to go back and cut some off after each flight.

In practice, no one measures line length during a contest, or after a contest, so the monofilament might give you an additonal 10 feet after 7 flights. But your line length could be contested.

I have an altimeter on my #1 F1A, quite accurate. So I can measure bunt height during every flight.

I am going to the Sierra Cup to fly F1A on October 14 at Lost Hills, and plan to test the 2 lines for performance. My feeling is that the polyester may not have as much stretch, but releases more energy at launch.

I flew with the M&K polyester last year during the team finals, and felt that I got much better launches with the polyester, until I had to go to my backup line. The backup line is 140 feet of braided kevlar, with 22 feet of yellow mono. The backup line did not do as well.

The reason I had to switch was that I was having trouble winding up the line quickly, and left the line to chase my model in a big boomer. Upon return, had a big ball of polyester line.

If you have a good line, make sure and wind it up well after each flight.

While test flying here in Minnesota at the sod farm, I leave the line out, and just drag the flag back to my launcher prior to retrieving.

I use a plastic tube launcher, and rarely have anyone with to launch.

[rivers]

Question for Jim: What is an ehook?

Question for Dave: Am I right in reading that the M&K line (Russian rod) is .040 dia. solid (monofilament), not .040 dia. braided (multifilament)?

[Anonymous]

This is my observations of towlines. Yea, the Russian Rod is stiff stuff, but there are other materials out there if you just take a minute to look. I have found Spectra to be the stiffest test pound per test pound.(least amount of stretch). And after all, isn’t that what we’re looking for? Anyway, the people that are using the most current style bunters. I use two lines…..one is 100# Spectra, high visibility yellow, with 200#, high visibility yellow Dacron at the lower 30′ or so. Then the other is 150# Spectra, phantom red, with 250# fluorescent orange Dacron, in the lower section. I also have some really cool secret stuff that I haven’t been able to measure any significant stretch in.

So, if any of you out there might be interested in getting the highest quality towline……just let me know….and I will be glad to make a towline or two for you. Of course, there will be a slight fee…..LOL 😛 So just write me and I’ll give you a quote. Jeff

[Anonymous]

I have to appologize for my previous post……I forgot to mention, Kevlar, though it is tuff…..keeps stretching. In other words, you’ll have to keep trimming your line length as time goes by. And then one more thing about Spectra…….the diameter is super small…….like the 100# is the same as what you would find 20# monofilament. Which equates to less drag during, highly accelerated launches.

Again, anyone wanting a towline, drop me a note and we can discuss what you would like. Jeff 8)

[Roger Morrell]

An e-hook is a circle tow hook where the line latch is controlled by a servo on the hook. On a traditional circle tow hook there is a spring loaded latch that when the required tension is reached the hook opens and the line can fall off. This is a one way action.

On an e-hook the latch can be closed if the launch fails. They have a unlatch and relatch tension. When the ‘timer’ senses the unlatch tension the hook is opened. However if the model is not launched and the tension drops below relatch point then the servo closes the latch and cicrle towing can recommence.

There clearly some big advantages but significantly increased complexity. In Jim’s posting he talks about handling gusts in very windy conditions. These hooks will relatch under these conditions but I recently added a gust debounce feature [as a result of customer input] this means that the relatch tension must be held for a extended period of time to smooth out wind gusts or sportsman tripping.

My timers support two ways of detecting hook tension, electronically with a hook mounted strain gage or with a spring and switch. For the electronic sensor hook the position of mounting of the strain gage as well as the bonding to the hook is very critical.

Roger Morrell – Magic Timers

[Anonymous]

Dave says “In practice, no one measures line length during a contest, or after a contest”. Nonsense. CDs measure lines at most World Cup and championship events including the MaxMen; its a requirement. So you need to ensure your line is legal at all times. People do get disqualified for illegal line lengths.

I have used M&K rod, kevlar, Salzer line, cat gut and weasel fur amongst others but its an individual thing. Jim is right, you need a low stretch line to get the best height gain from a model and the M&K is probably best. However, I find it slippy without gloves, it can coil and is difficult to knot although there are ways around these problems I guess. I use a 100lb spectra line with a orange dacron cover which is manufactured for kites. It stretches a little more than the M&K rod but I find it is much easier to hangle, you can find it in the long grass easier and it matches the colour of my eyes. I can send you details if you like.

As I said, its an individual thing. I’d suggest you start with something cheap of at least 100lb test with something at the bottom end to increase grip. Also use gloves or tape over your fingers unless you like cuts.

[Author]

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