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Author Topic: Looking for Information on Viscous Timers  (Read 812 times)
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ScienceGuy
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« on: March 02, 2018, 09:32:53 AM »

I am working on an article on viscous DT timers, my experience is somewhat limited but I have been doing some bench testing and searching the Internet for any articles.


This is just a few questions I had you might have seen my blog post on viscous timers: http://scienceguyorg.blogspot.com/2018/02/bad-experiment-in-viscous-dt-timer.html



For example:  What is the history of the Badge/Munson timers? Were they manufactured for model use?

Do they have more of the viscous fluid as they are larger than other timers?

Does the consistency of the timer suffer as the spring gets stretched out even slightly, meaning it doesn't return back to where the coils are tight.

What is the opinion of the Ikara timer?  Building you own from rotary damper?

Do you spin the timer through a couple of times the start of flying session?

Is there a general amount that can be changed for changes in temperature?

Have you tried making a Silly Putty timer?   How does it compare?

Do you feel a fuse is a lot less bother?



Just some ideas, anything anyone can contribute would be Welcome,

Bill Kuhl
scienceguy33@gmail.com
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applehoney
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« Reply #1 on: March 02, 2018, 01:21:40 PM »

>Do you feel a fuse is a lot less bother?

Sure do.    Have tried viscous, clockwork and electronic band-burners ... prefer the fuse.
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ScienceGuy
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« Reply #2 on: March 02, 2018, 01:33:13 PM »

I am finding people either like the viscous DT or they really do not like them.  Think I might be in the middle but giving it another chance.

Bill Kuhl
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RalphS
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« Reply #3 on: March 02, 2018, 03:34:08 PM »

I can give a UK perspective.  I saw an article in an Aeromodeller magazine about the Badge timer - how it had cost a lot in development and was priced at about £15 to £20 each.  At the time I had a small engineering business and used to purchase many nice injection moulded items made by a Dutch company named "Skiffy".  They were imported and distributed in the UK by a importer whose name I forget.  Skiffy produced a lovely small catalogue and used a gifted artist to embellish their product description - think drawing of women wearing earrings made from plastic washers or whatever.  The next catalogue that was sent to me included viscous dampers in various strengths used for damping the closure of flaps and covers, etc.  They looked very like the Badge damper so I asked the importer for a sample and price.  The sample looked interesting when I tried it on a test rig.  I asked for a quote that was for the minimum order of 1000 items and sent an order.  I received the dampers, was invoiced, and I paid at the next due date.  The FF Nationals came up and I took the test rig and the dampers along to see if there was any interest.  I charged 50p (£0.5) each - much cheaper than £15 for a Badge.  I sold about 300 at the Nats. in one day;D

Back at work I had a phone call from the importer who sounded a bit worried.  He said that he had made a mistake and would I return the dampers.  He had charged me 10p (£0.1) each and it should have been £1 each.  Sorry, I said - you quoted, I ordered, you invoiced, I paid - end of the matter.  Even at the full price there was a great saving for essentially the same thing marketed as the Badge timer but I wouldn't have ordered a 1000 at £1 each

My damper timer was featured in one of the Aeromodeller columns and I got orders from Scandinavia, Japan, USA, Australia and some other countries that I forget.

Being busy enough in my business I passed the rest of the items to Freeflight Supplies in the UK who still lists them I think.  Flitehook, another UK supplier had a similar thing made in the Czech Republic.  There must be thousands in use on HLG/CLG and small models.  They can be inconsistent because they need external power - usually rubber bands.  The damper slip rate varies with temperature and we all know how rubber power output varies with temperature.  However, I have found that they always work - eventually.

I think that the Badge people were guilty of overcharging.  I have seen that RDT units are fitted to CLG's in the US.  These are a lot more reliable I suspect but not as cheap.

I wonder how many have been fitted to models all over the world?

Ralph

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ScienceGuy
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« Reply #4 on: March 02, 2018, 05:03:03 PM »

Any idea what issue the article on the Badge was in Aeromodeller, I would like to read that?

Rotary dampers used in a variety of products are mass produced, if it is made by a single person vendor I can see the higher price.

I found this video of rotary dampers being mass produced:  https://youtu.be/PzY1-b4E7BU

Thanks for your interesting story.

Bill Kuhl

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PeeTee
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« Reply #5 on: March 02, 2018, 05:15:17 PM »

Hear hear Ralph!
I used your timers around 20 years ago and very good they were too! Living down south I discovered the timers sold by Flitehook (used by Ikara )and used these instead. I discovered the Ace Controls FRT-E2-400 which were smaller and lighter and were good for CLGs ( I gave some to Phil Ball to use) and these are now used by a US supplier.

Time dims the memory !

Peter
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Yak 52
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« Reply #6 on: March 02, 2018, 06:11:37 PM »

Peter also gave me one to try a few years ago and I ended up doing a bulk buy for our club Smiley You can get them down to about 0.3g and actuate them with fishing pole elastic. There's a little variability with temperature but I have yet to manage anything else quite so light. Used very successfully on a small CLG with a Ralph Ray type pop up wing.

Jon
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atesus
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« Reply #7 on: March 03, 2018, 05:33:34 AM »

If I recall correctly, the gentleman who used to make the Badge timers stopped producing them recently. I heard he had a small workshop in his apartment -on the east coast of US, don't remember the city, could be NYC- where he was manufacturing the timers. Our club used to make bulk purchases  which were then passed on the members at cost. In California, we cannot use fuses since they pose a fire hazard, so Badge timers and Tommy timers are very popular. I'll try to get more details on the Badge timers.

And here's an excellent write-up by our club member Manuel Cisneros on making inexpensive timers out of viscous dampers that might be of interest.

http://www.oaklandclouddusters.org/resources/Documents/Articles/In%20the%20Workshop/Rotary_Damper_Timer_Build.pdf

Best,
--Ates
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RalphS
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« Reply #8 on: March 03, 2018, 05:44:29 AM »

Any idea what issue the article on the Badge was in Aeromodeller, I would like to read that?

I have been retired for 21 years so I guess it was a couple of years before that - say 1994.  I think that it was in one of the regular columns by Trevor Gray or Mike Evatt.  I disposed of my Aeromodeller magazines so can't look it up.

[/quote]Rotary dampers used in a variety of products are mass produced, if it is made by a single person vendor I can see the higher price. [/quote]

Seems a silly route to take if the basic item is commercially available.

I have found one of my original packets containing the damper and instructions.  I will copy or photograph it and post it here.

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cvasecuk
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« Reply #9 on: March 03, 2018, 06:36:02 AM »

In Aeromodeller August 1995 Trevor Grey reviewed the "Button" timer. It was not until April 1996 that another article appeared which included Ralph's details on how to modify a viscous damper.
Ron
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RalphS
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« Reply #10 on: March 03, 2018, 09:42:01 AM »

Thanks for the Aeromodeller dates cvasecuk.  You must have a pile of Aeromodellers!  It used to take some time to get articles into print in those days.

Here are a couple of pics of my original instructions and damper.
 
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Yak 52
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« Reply #11 on: March 03, 2018, 10:02:01 AM »

With PeeTee's Ace Controls damper I found it was possible to simplify things to just a short piece of piano wire CA'd into a hole drilled in the damper spindle. The lugs are cut off, the rear roughened with sand paper and then it's glued straight in. Be careful not to puncture the case though as the goop oozes out  Roll Eyes (The photo shows a version buried in a CLG fuselage faced with 1/64th ply.)

The pole elastic is a 50mm length of 0.98mm Slip System size #5. The thread is Nylbond.

One thing I learnt was not to take it off the shelf and fly it without rotating the damper a few times to loosen it up. And check times against the watch before flying with it. It also makes sense to place the damper somewhere where it can be held easily until you are ready to launch.


Jon
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flydean1
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« Reply #12 on: March 03, 2018, 11:20:34 AM »

I've used viscous dampers as timers for years.  (20+).  Superior to fuse.  When I started to fly Nos Gas in the mid-90's had issues getting quick launches lighting fuses.

There are a few pictures on the Texas Timers website of my Mini-Pearl setup.  I also used a detachable loop of monofilament to make a quick DT, bypassing the timer.  Then removed it for longer DT times.

As mentioned earlier, you must pre-rotate them before flying, and you must calibrate them daily before flying as they vary slightly with temperature.  Never had to fly in really cold conditions in Florida.  Fuse burn times also vary with humidity especially so no real difference there.  Initial setup is a real bother.  I finally went to springs wound from .009 guitar strings.  The problem was; enough tension to hold the stab down vs timer running speed.  This is largely solved with some sort of lever in the DT line, or a 2-spring setup where one runs the timer and the other holds the stab line.  Yes, far more complicated than a fuse, and slightly heavier, but I generally build sleds anyway. Roll Eyes

Using these, my time-to-launch went from a minimum of 30 seconds to a minute, depending on lighting the fuse.  Now from decision to launch 20 seconds is easily achievable.  This is especially useful at a place like Muncie in the afternoon when thermals are smaller and hard to pick.

So you pick your own poison.
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Red Buzzard
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« Reply #13 on: March 03, 2018, 12:15:45 PM »

Hi All,

I have been using the viscous timers (Badge, Button I can't keep track) on rubber models since the mid '90s. In fact I haven't used a fuse since my early FF days in Southern California in the '60s. I have flown them from 2 minute maxes up to 6 minutes but as flydean says, when you get up to the high maxes it is a battle between stab hold down and diminishing tension as the timer unwinds. You can put in a lever or use a capstan to add friction or mechanical advantage. Here are a couple of pics of my set-up. By the way my gas models are all clockwork timers.

The first shows the basic set-up. Of note is the small knot on the monofilament where it joins the first hook. This knot MUST NOT be allowed to go through the slots on the release lever. It can jam the mechanism as it tries to go around the radius as the arm unwinds. Also, I use various sized rubber bands for springs depending on the heat of the day and the length of the max. I have never used the elastic cord that comes with the timer as it, too, can jam the lever as it unwinds. You can of course use the cord as a spring, but not over the lever. In general I follow flydean's procedure of giving the lever a couple of revolutions before a flying session and check the speed through the day as temps change. For me, the timers have always run more slowly in the air than on the ground and I usually anticipate at least 30 seconds long on a max. I have never had one run fast and have never had one fail.

The second image is just a couple of the bands I use. Just commercial bands from the stationary store.

Bill
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