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Author Topic: Flier seeks help re rubber  (Read 713 times)
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tomtflyer2019
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« on: April 04, 2019, 05:30:57 PM »

Hi all,
First of all, apologies for intruding on your outdoor forum.
I am a 77 yr old flier who has flown all disciplines since 1958. For the last 20 years or so I have concentrated on indoor rubber duration with a fair degree of local success including National Champion in F1M (UK).
I am stuck in my progress because I can't find any good rubber (May 99 esp).
It occurred to me that outdoor fliers might have some very short lengths left which are of no use to them. A metre would go a long way in my world!
I would be happy to pay for the rubber and postage if you had any short lengths (even just one!)
Again.. apologies for intruding, I don't mean to offend and will understand if I receive no replies.
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calgoddard
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« Reply #1 on: April 04, 2019, 11:52:30 PM »

Tom -

No apologies are needed.  I believe that your inquiry is a reasonable one and will be warmly received on this forum.  

Congratulations on your indoor flying success.

I fly both indoor and outdoor rubber powered free flight.

Over the past ten years, I don't recall ever recall seeing, or hearing about, outdoor fliers using May 99 TAN II for flying outdoor models.  It seems as if it is too rare and too valuable.  I know that at least one flyer on the U.S. F1D team flies exclusively with May 99 TAN II.  But an F1D model only uses 0.4 gram motors. As you know, Wakefield (F1B) models use 30 gram rubber motors.  I have seen a few top notch F1B fliers fly their models. They only use each motor once in competition. They wind to the absolute maximum limit. So I am not sure their discarded rubber motors would be all that good for indoor flying.  As to remnants in making up rubber motors for outdoor flying, I don't know what those fliers do with them.  It seems to me that only serious F1B, F1G (coupe) and P-30 outdoor fliers would be all that concerned with having the very best rubber.  All other outdoor rubber free flight fliers, including those that fly scale, FAC and sport models, don't seem all that concerned with having top notch rubber. They seem more concerned with optimum trimming and motor sizing, winding and picking thermals.

It is my understanding that pretty much every batch of Tan Super Sport rubber starting in 2009 is very good. Some batches of Tan Super Sport rubber are better than others, of course.

You might have some luck purchasing some TAN II rubber on eBay, but I doubt anyone would sell May 99 TAN II on eBay.  I was able to purchase some TAN II rubber on eBay several years ago, but it was not May 99.  I found its performance in connection with my indoor stick duration models (including Limited Penny Plane, A-6 and Wright Stuff) to be no better than the performance of the better batches of Tan Super Sport rubber.

I wish you luck in your search. Please let me know if you could share any extra May 99 TAN II rubber with me.  I would gladly pay you market price and shipping for the same.  

Welcome to the Hip Pocket Aeronautics community. I look forward to your future posts on this website.

« Last Edit: April 05, 2019, 12:02:54 AM by calgoddard » Logged
BG
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« Reply #2 on: April 05, 2019, 09:38:41 AM »

Re. May 99 ... get in touch with Tony Matthews. I think he has some short pieces for sale (maybe).

Re. modern TanII: Tan II is not "all good". Some batches are significantly better than others. For example April 2016 was a particularly good batch, although not every segment in the batch was good it did seem to yield a lot of very good rubber. Of course as a B flier I am concerned with the performance of 30g segments so I can't speak to how it looks at higher resolution.

The person who has tested most of the TanII batches in recent years is Tom Vaccaro. He might be able to give some insight into what would work well for indoor needs.

BG
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F1B guy but its not my fault, Tony made me do it.
tomtflyer2019
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« Reply #3 on: April 05, 2019, 11:25:30 AM »

Thanks for the helpful replies. No success yet, but I'm hopeful....Cheers!
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adanjo
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« Reply #4 on: April 06, 2019, 04:40:31 AM »

Don't you have any other competitive batches like Mar 02?

Aki
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tomtflyer2019
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« Reply #5 on: April 06, 2019, 06:19:07 AM »

Just running out of my last little bit and trying succession planning!!
Thanks for the interest.
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kkphantom
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« Reply #6 on: April 11, 2019, 09:01:17 AM »

I have almost a full, 1lb box of May'99 tan II. I don't fly indoor, and I bought it from the local hobby store who was selling it at 60c per metre. I have no way of testing it to indoor standards and it may well be past its prime.
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cglynn
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« Reply #7 on: April 11, 2019, 09:07:37 AM »

For what its worth, the 6/16 batch of Tan Super Sport is reputed to be very good rubber.  In testing, it has shown to have a higher energy capacity than 5/99 Tan 2, but that occurs right at the top end of the torque curve.  For flying indoor with 6/16, that means a longer loop of the same length to get the turns and torque you need.  For outdoor flying, where the goal is to launch as high as possible, I would think that the 6/16 rubber would work very well.  Also, as of now, it has not reached the astronomical prices that 5/99 has.

I have also heard that the modern batches of Tan Super Sport are fairly consistent, so should be similar in performance to one another.  I cannot however confirm that as I have been flying on several batches of rubber, and have not purchased any of the newer stuff.  

If you check out the indoor forum, there is all sorts of discussion about rubber, testing rubber, and quality of different batches.  
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tomtflyer2019
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« Reply #8 on: April 11, 2019, 09:12:46 AM »

Thanks for the reply. I'd have to take the risk on storage/ condition.
Would you be prepared to mail me directly with a price which you think is fair.?
Cheers
Tom
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kkphantom
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« Reply #9 on: April 11, 2019, 09:29:25 AM »

PM me with your address and I'll put a metreof it in the post for you, gratis. Do what you like with it and if it's what you're after we'll discuss further. I'm coming to the UK in May for the nats  and all my rubber is coming with me along with all my other crap er stuff!
Gary
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calgoddard
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« Reply #10 on: April 11, 2019, 02:00:59 PM »

Let me further muddle the situation.

I have a good friend who is a world class flyer.  Certainly he is one of the best free flight flyers in the United States.  He has been flying for 50 years, and competitively for at least 40 years.  He is very, very meticulous.  It is virtually impossible for anyone to beat this flyer in a contest unless he encounters rare bad luck.

Anyway this friend tested what I believe was 5/15 TSS rubber with his very methodical, detailed, rigorous scientific test which involves stretching, winding, and measuring torque at specific intervals, recording the data, and analyzing the same. He said that the sample of the 5/15 TSS rubber was the single best rubber he had ever tested.  I assume that he was including various batches of TSS, TAN II, Pirelli, and whatever came before Pirelli.  He did say something similar to what cglynn said about 6/16 TSS rubber, namely, that the 5/15 TSS rubber had a particularly good high end on the torque versus turns curve.  So I am not sure if 5/15 TSS would be good for indoor flying. It would certainly be good for Wakefield, coupe and P-30 competition where many flyers want a huge burst of torque upon launch to reach max altitude.

Note that the box containing the 5/15 TSS rubber was not marked with that date in the usual fashion.  But the rubber obviously came from FAI Model Supply and the TSS batch date was determined from the shipping label. It would be nice to know if there was in fact a 5/15 TSS rubber batch. Does anyone know the answer to this question?  Thank you in advance for your help. Sorry for going off topic.

tomtflyer2019 - I am glad you found some May 99 TAN II.
« Last Edit: April 11, 2019, 02:18:14 PM by calgoddard » Logged
Tapio Linkosalo
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« Reply #11 on: April 12, 2019, 01:39:46 AM »


I was about to suggest the same - some batches of Super Sport are about as good in energy return as the best Tan II, so it might be worth trying them out. Moreover, the -99 vintage of Tan II is now 20 years old, and may be past its prime. I still fly with some July -99 rubber, and I have found out that all my motors break on 2nd or 3rd wind latest, which to me indicates that the rubber is turning brittle. May batch seems a bit better in this respect, but I expect that it will be over the hill shortly, too.

Granded, Super Sport has different torque curve - stronger peak and flatter, lower cruise, so the usable energy for indoor may be less (if you need to back off that torque peak). And in any case it would require different setup for the prop. For myself, I intend to build new props for the classes I fly and adjust there for Super Sport only, as I feel I need to prepare for the day that my Tan II turns to be too brittle to use. I think I will see that day soon, and I want to be prepared for the Super Sport takeover!
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tomtflyer2019
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« Reply #12 on: April 12, 2019, 07:10:53 AM »

First of all, I'd like to thank members of the forum for such a good welcome. I'm hopeful that I may get a small  amount of good rubber from one or more of the kind contacts I've had.
I can see that inevitably the discussion is turning to the relative performance of different rubber and I am not really qualified to offer "expert" analysis, so I will follow the discussion from now on, rather than lead it.

What has been fun and interesting for me is to be reminded of the different needs of indoor and outdoor fliers in terms of torque distribution from a motor. This is esp. true in the UK where our halls are much lower than some other countries. There is also the issue that the number of turns available is probably more crucial to an Indoor model like an F1D as it doesn't have a "glide" phase. So no help from thermals to speak of (hall conditions can slow the come down, but usually the model lands with the last few flicks of the prop). As I would be trying to get something like an average of 45 rpm from the prop in flight, I can get a good estimate by dividing the number of turns by 45! The weight of an F1D is 1.4g including a 18" dia (ish) VP prop and the rubber allowance is 0.4g. No energy to waste at all! Maximum efficiency in terms of rubber energy is vital. I have found that the shape of the turns/torque curve is more important than max torque available, with more useful work under the cruise phase, rather than the high torque. The top UK fliers like Tony Hebb and Mark Benns extract amazing performance from all factors. They spend a lot of time minimizing power off "glide" sink rate. They also get max turns on the motor and spend a lot of time tuning model/motor prop combinations.
Using a motor which has high torque output, which then falls off quickly results in a fast climb to the ceiling, spinning off turns quickly, followed by short cruise/descent. Increasing prop pitch/diameter to counteract this brings its own problems. A bigger prop requires a shift to maintain the CG position, risking  the wing being very near the prop arc and adding weight which can't be afforded. In my own limited tests of rubber, based on actual flight (nothing as sophisticated as some contributors), I have found the following:

October 97 has too much high end torque, doesn't take as many turns and seems to be to be getting brittle.
March 02 is a shade thinner than other rubbers, isn't as good as May 99, but is really resilient with a good torque/cruise distribution. It takes more hard winds before getting tired.
Mixed results with Super Sport. I tested a batch (undisclosed year!) for a friend and it was as good as May 99, but would only take 2 hard winds before breaking. Other batches have only been good for sport flying.
From the VERY small amount of May 99 (I was gifted by John O'Donnell), I found that it gave significant performance increase, peaking on the third wind, following a break in wind to 65%
I hope this doesn't sound like teaching my Grannie to suck eggs!
Thanks for all your help.
Tom

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calgoddard
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« Reply #13 on: April 12, 2019, 10:14:01 AM »

Tom -

What a beautiful F1D you have indeed.

Your insights on the qualities of rubber best suited for indoor duration models are very astute.

I am a jack of all trades when it comes to free flight.  I fly both indoors and outdoors, everything from coupe, P-30 and Old Time Rubber, to FAC models, to Limited Penny Plane (LPP), and A-6.

As previously noted in an earlier post of mine, in outdoor free flight the quality of rubber is not as important as it is in indoor free flight, for a lot of reasons.  I must admit that I have gotten the best performance with my best LPP with May 99 TAN II.  I estimate that the performance of this LPP with that rubber over dozens and dozens of flights is roughly 5% better than with any other rubber it has been flown with.  I had so little of that rubber that I used the same motors in several different contests and it got excellent results with maybe as many as nine hard windings, about three per contest spread out over several months. As you are well aware, eventually all indoor rubber fatigues to the point that it is no longer competitive to fly with the same.

I wanted to relate a little history of rubber used in free flight as I understand it from hearsay. I have no credible sources that I can cite. You may already be familiar with some, or all of this history.  I may be misinformed as to some aspects that I will relate.

In the 1960’s free flight model airplanes were flown with Pirelli rubber. Thereafter, supposedly a dedicated free flight modeler worked with a rubber manufacturer and developed TAN rubber. Somehow TAN rubber was related to the rubber used to wind the cores of golf balls. An improved formula was developed and sold for many years known as TAN II rubber but the quality of this rubber varied significantly from batch to batch. Eventually golf balls converted to a solid core and the key ingredient used to make TAN II rubber was no longer available. An ever diminishing amount of TAN II rubber still exits and can sometimes be purchased on eBay or acquired from estates. Sometimes other flyers will sell or give away quantities of TAN II rubber.  The May 1999 batch of TAN II rubber is legendary for its quality and many indoor records have been set using this rubber.  I have observed that our club’s own Kang Lee, a two time world F1D champion, flies exclusively with May 1999 TAN II rubber. Shortly after the manufacture of TAN II rubber was discontinued, Tan Sport rubber was introduced. Then an improved rubber known as Tan Super Sport (“TSS”) was introduced. It is currently sold by FAI Model Supply. By 2005 its batches were reasonably good, but not as good as the best batches of TAN II rubber.  I understand that TSS rubber is a hybrid of natural rubber and synthetic rubber.  To the best of my knowledge the formula for TSS rubber is a trade secret. TSS rubber is the only rubber that is currently manufactured and sold that is suitable for free flight, at least as far as I know.

According to experts, including Don DeLoach, since 2009 all batches of TSS rubber are “good.”  

Tom, you are obviously an expert and know a lot about testing rubber and what makes rubber good for indoor duration flying. The following discussion will hopefully help others who have not achieved your level of expertise.

So why bother testing your rubber?  The answer is that you may have old rubber in your inventory that needs testing to see if it is still worth flying with.  Rubber deteriorates over time, especially if it has not been properly stored. Moreover, just like wine, all batches of rubber are not equal.

A crude test for rubber quality is the hand stretch test.  Pull a short segment of the rubber between your two hands.  Based on your experience, if it does not feel “real stretchy” it is probably no good.  In other words, if it feels like a Staples® office rubber band, consider pitching this batch of rubber into the trash.  As a general rule of thumb, the rubber used in free flight should be capable of stretching at least 6 - 8 times its relaxed length.  I have read that some rubber can be stretched up to 10 times its relaxed length.  Make up a single loop of the rubber that you want to test that is one foot long.  Secure one end of the loop to a winding stooge. Lay an extended tape measure out in front of the stooge.  If the loop won’t stretch to at least 6 - 8 feet in length, the quality of the rubber is suspect.

A more scientific approach to testing rubber involves winding a rubber motor made from a given batch of rubber that is the size you intend to fly with, e.g. a P-30 motor. My preferred P-30 rubber motor is a 6 x 1/8 inch 9.8 gram rubber motor that is approximately 19 inches long.  Lube the rubber motor. Stretch it 6-8 times its relaxed length.  Put in about half the estimated max turns with the rubber motor fully stretched. Then put in the remaining estimated max turns as you gradually walk in until the wound motor has a length equal to the hook-to-hook or hook-to-peg distance.  Keep winding until the motor breaks.  Compare the number of turns that caused the rubber motor to break to the data set forth in the graphs made by Don DeLoach and Dr. George Mansfield.  Preferably this winding test should be done with a torque meter and both the breaking turns and breaking torque should be recorded.

Serious fliers determine the energy storage capability of rubber in terms of foot pounds per pound of rubber. The precise formula is set forth in an article entitled “A Quick Rubber Test” by Hank Cole published in a July/August 2003 edition of The Southern Louisiana Indoor Modeling Journal.  I am sorry I am not able to reproduce the formula here.

Super serious F1B and F1G fliers stretch rubber on a motorized jig, and plot the forces on a computer display both as the sample is stretched and as it is relaxed.  The curves are of course similar in overall shape, but different in important respects.  Indoors I understand that that "flat" part of the curve during the unwind is the critical portion where most of the duration is achieved.

There is one more tidbit I wanted to add.  The hysteresis of the rubber we fly with and its capabilities for storing and yielding energy vary with temperature. It is my understanding that you will get better performance of the rubber in terms of powering a model airplane in higher temperatures.  Someone told me that in the olden days, flyers used to heat their rubber motors used in in outdoor flying. The practice was supposedly banned due to safety concerns.    

  

  
« Last Edit: April 12, 2019, 11:32:53 AM by calgoddard » Logged
Sharbonda
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« Reply #14 on: April 14, 2019, 10:01:52 AM »

Nice history, but you forgot the dark fai rubber between pirelli and tan which was very nice and forgiving!
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flydean1
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« Reply #15 on: April 14, 2019, 11:07:14 AM »

Right.  I call it Black Champion.  I think FAI stocked it too.  Still have some that I use for testing using oversized motors wound to no more than 50% torque.  Also use it for catapult gliders as it is "stiffer" than Tan SS so easier to come to max stretch for my short arms.
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