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Phil Barnes
100 Posts |
 Posted - 09/13/2004 : 09:14:20 AM
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CASA Open 2004:
With nine rounds of flying and 42 contestants on saturday the winches must have performed over 350 launches on 800' launch lines. Only one winch related problem occured; The solder joint to one of the "hot" brushes failed. That was my fault, I must have done a poor solder job on that connection the last time that winch was overhauled. No delay to the contest resulted as the other two winch stations handled the launching duties while I replaced that winch with the fourth ESL winch which was in reserve.
I tore down the broken winch once the day's flying ended with the intention of installing new brushes only to find that the soldering iron I had brought to the field had quit working. I was forced to take the winch home and fix it on the bench that evening.
On Sunday we flew 8 rounds with 31 contestants for another 240 or so launches. Late in the day, an electrical burning smell was noted and eventually traced to the solonoid mounted underneath one of the winches. This is the first ever solonoid failure on any of the ESL winches. The bad solonoid will be replaced prior to the LISF contest in two weeks.
There is one other concern with the winches. I have always been paranoid about stripping out the threads in the aluminum "Real Balls" endcaps when tightening the two long case bolts that hold the winch motors together. These motore get rebuilt two or three times every season so these threads get a lot of use. It finally happened on one of the winches so now that winch only has one case bolt holding the end caps on. I will try to find a fix for the problem. A slightly longer bolt may be able to reach some new threads in the endcap since the old bolts did not go all the way into the threaded hole. Failing that, it may be possble to run a bolt or threaded rod all the way through the endcap and put a nut on the outside of the endcap. In the end it may be necesary to buy a new "Real Balls" end cap but that is an expense I would hope to avoid. Especially since I might expect the problem to eventually recur with other endcaps.
There were essentially no line related problems all weekend. Two things have happened which have almost completely eliminated winch line breaks. Number one and most importantly, was that the guys in the DBSF club (Terry Luchenbach, Dale Hart, Ron Bates ???), a year or two ago, discovered some nicks on the inside edge of the winch drums that were cutting the winch line. They filed those rough spots away. The second thing was that we switched to even heavier line than what we had been using. We used to go through about two cases of winch line in a season and suffer through numerous line breaks every contest. This season we have a case of winch line which has been almost untouched all season.
We did have one "line break" on Saturday which I did not personally see and was not able to determine the cause of. It didn't look like a classic line break and was quickly repaired. The broken end was only about 1/4 of the way to the turnaround. No other trips towards the turnaround were made all day on Saturday.
On Sunday we had one airplane which remained attached to the launch line when it should have released. That plane rode the launch line all the way to the ground and required a trip out to the turnarounds to clear the lines. We had one retriever bridal which broke on launch and did a great imitation of a line break. What actually happened was that the knott to one of the welded rings broke. This was not a "line break" just a failure of the knott where the heavy bridal line was tied to a steel ring. No other trips out towards the turnarounds were required.
I was kept busy on Saturday with the CASA retrievers. These are not ESL equipment items but are well known to contestants who fly many of the ESL contests. There are six CASA retrievers, all built by the late Don Clark betweeen 1984 and 1992. In those days the CASA Open drew around 100 contestants and six sets of equipment were needed. The problem with the CASA retrievers is that the wiring is old and the retrievers tend to be left out in the rain or morning dew a lot. So there is a lot of corrosion in the wires/connections. I hope to find the time to completely rewire/rebuild these retrievers someday. Until that happens I have to rely on the current system which involves finding the bad spopts in the wiring by just using the retrievers at the big Open contest. The hard hammering the retrievers get with the fast launch pace quickly reveals the bad spots. When the retrievr begins to run slowly. we just feel around all of the connections and wiring for a hot spot. Once found, it only takes a minute or two to swap out that retriever with another (the luxury of having six CASA retrievers) and then Take a few minutes to clean up a bad connection or cut out the corroded wire end. All of the bad spots were fixed on Saturday and the retrievers ran without trouble on Sunday.
Of course, the biggest reason for the smooth operation of the launch equipment at the CASA Open is the excellent crew of experienced operators that we have at CASA. No other ESL club has as many experienced and dedicated workers who are willing to sit out all weekend in the sun to run a retriever and help set up and tear down equipment. We all owe a huge debt of grattitude to Henry Elliot, Chuck Kayser, Stoney Jasper, Antonio Quesada, and Kerry Cochral for their hard work and dedication. Skip Schow and Bert Magin also took time away from their scoring and CD duties to fill in when the regular operators took time out to fly.
Phil |
Edited by - Phil Barnes on 06/13/2005 09:12:36 AM |
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paul
13 Posts |
Posted - 09/13/2004 : 3:42:09 PM
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| and we forgot to mention Phil's dedication and hard work throughout the weekend. paul |
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pjschlit
1 Posts |
Posted - 09/15/2004 : 10:07:07 AM
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The stripped holes can be fixed using the Heli-coil method. I would be willing to deal with the stripped end caps over the off-season.
The entire lot would benefit from this treatment, if they are repeatedly disassembled .
Pete
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raschow
8 Posts |
Posted - 09/15/2004 : 1:39:40 PM
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AMEN, Pete. I will check local auto parts sources & advise Phil on near term fix of the bad one. Bolt thread size is 1/4x20 I think?
Good Lift! Skip PS: In CASA we NEVER forget Phil's dedication and hard work, thnx again, Phil!
Good Lift! |
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Phil Barnes
100 Posts |
Posted - 06/13/2005 : 10:16:32 AM
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LASS 2005
The Lancaster contest was small this year, a little under 20 contestants. They ran three winch setups. It was a small contest but the winches got a hard workout anyway due to the fact that at least five of the contestants have F3J aspirations and seamed intent on honing their F3J launch skills. An F3J launch is a rather brutal afair requiring extreme launch line tension and a massive zoom. To simulate this on a winch requires the plane to keep its agressive F3J launch setup. This agressive launch setup will cause the plane to launch at a very steep upward angle and to avoid stalling the plane on launch a very large winch line tension is required. The required launch line tension is just a little shy of what is available from a Ford long shaft winch motor being run on from an old battery and is just about the max tension available when using a stronger battery.
I timed for Tom Kiesling all weekend and soon learned a couple things. First was that the old ESL winch batteries were in need of replacing. The extremely agressive launches quickly depleted the batteries and the chargers were unable to keep up with the drain. Tom got some valuable experience dealing with awkward attitudes on launch as the model veered from side to side due to the lack of line tension that the winch could provide from the old batteries. The winch motor would be completely stalled for a large part of the launch. Later in the day after the winch batteries were swapped out with some better batteries from the Lancaster club, Tom's launches became a little less eratic but the winches just got hammered even more.
So the winches took a real beating that weekend. A few F3J hardcore types doing maximum winch stalling launches and, of course, most of the other contestants emulating that behaviour. The second lesson learned from this experience was that it is indeed possible to over stress one of my Aegea Mantis wings using the ESL winches. Dave Walter and John Nilsson have now embarked on a project to repair center section creases in their Aegea wings. The lesson for the rest of you Aegea wing owners is that you should not engage in this sort of winch stalling maximum line tension launching. Ordinary hard launches should be OK, just avoid the peer preasure to keep up with the winch stalling type launch should that behaviour show up again at an upcoming ESL contest.
There was one winch failure at this contest. A major internal short circuit ocurred which completely fried the winch. The primary failure apeared to be the little insulator that isolated the brush holder bolt from the end cap. The "hot" brush holders are attached to the end caps with two small bolts. these brush holders need to be electrically isolated from the end caps and from the two small bolts. There are fiber insulators between the brush holders and the end caps. The bolt is isolated with a little piece of heat shrink tube over the bolt and a fiber washer under the bolt head. When that little piece of heat shrink failed, the bolt then contacted the brush holder and an electrical short ocurred. The bolt (a little 6-32 bolt) became the weak link in a dead short and immediately melted in half. This allowed the brush holder to pivot around the remaining bolt until some part of the brush holder assembly contacted the winch frame. The new weak link became the little coil spring that provides preasure to hold the brush in contact with the armature, the coil spring melted in half. the fireworks finally stopped when the solder joint between the hot brush and the field coil heated up and melted which disconnected the brush holder assembly from the hot side of the circuit.
I took that winch home and repaired it Saturday evening. The fried brush holder bolt was melted/sheared off flush to the end cap so I had to grind a slot in the bolt end with a dremel cutoff wheel and then use a small screwdriver to remove the bolt. Fortunately, the bolts are a loose fit in the end caps and it does not take much to remove them. We have a supply of the little insulators obtained from the armature shop so I was then able to locate a spare bolt from my culch collection and re-assemble the brush holder to the end cap. I replaced the melted brush spring with one taken from a personal winch. I'll try to get some spare springs from the armature shop next trip there.
This malfunction actually happened once before about two years ago. That is why I happened to already have a supply of the little insulators on hand.
The rest of the winch rebuild was just the same as an ordinary rebuild; new brushes and a freshly turned armature. Total job took about two hours and the winch was returned to service on Sunday. |
Edited by - Phil Barnes on 06/13/2005 10:17:27 AM |
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Phil Barnes
100 Posts |
Posted - 06/13/2005 : 11:00:33 AM
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SKSS 2005
The Silent Knights Soaring Society hosted a contest with about 20 contestants.
Four new winch batteries were available for use. The only winch related problem during the contest was that the batteries became depleted towards the end of Saturday. The batteries were kept on charge with a generator and battery chargers. My only theory as to why the batteries became discharged is that the battery chargers were of the automatic rather than manual type. Automatic chargers have some sort of circuitry to detect when the battery is fully charged and shut off the charge at that time. I wonder what the circuitry would do when confronted with the unanticipated electrical environment of a winch launch, perhaps the automatic chargers were shutting down after each launch. Based on this theory, the SKSS guys switched the chargers around and put manual chargers on the winch batteries on Sunday. The batteries remained fully charged all day Sunday.
Paul Bell packed up the winch equipment to take it to Long Island for the LISF contest in two weeks. I asked Paul not to charge the batteries if they remained above 12.5 volts. I did some research prior to buying this new set of batteries. Common wisdom seems to be that these batteries are damaged by overcharging or by extended periods of inactivity where they become discharged. I talked to one guy where I bought the batteries and his advice was that a fully charged battery will indicate 12.5 - 12.9 volts and that 12.0 volts indicates a battery that is half charged. I have been monitoring the voltage of these batteries since I bought them and so far they are following that pattern. When bought new with a full charge they all read right at 12.6 volts. I hooked each up to an automatic charger to see if they would take any additional charge. The charger would shut off after just a few minutes. Immediately after disconnecting the charger, the batteries would read 12.9 volts. Within 30 minutes of disconnecting the charger, the batteries would read 12.6 volts again.
I took one winch back to my shop for a rebuild. The hot brushes had worn down to a point where I wasn't sure that they would last through an entire contest day at Long island. John Hauf runs a contest format that requires all four winches to be used simultaneously so I did not want to run the chance that this winch would die half way through Saturday. You would not normally expect a winch to need rebuilding after just two small contest weekends. I think that this one winch was used disproportionately more than the others. The other three winches had lots of brush material left. I will deliver the rebuilt winch to LISF when I arrive saturday morning. |
Edited by - Phil Barnes on 06/13/2005 11:02:43 AM |
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