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Post by thevon on Sept 5, 2009 7:34:29 GMT 10
There's a thread on RC Groups about 2.4 lockouts, and since we've been discussing it (in the DLG fun thread) it would be good if the guys who've had problems (Sean, Nick, Pij and any others) check the thread and contribute. www.rcgroups.com/forums/showthread.php?t=1106184#post13039380did a bit more looking - lots of rather vitriolic arguing on this one! www.rcgroups.com/forums/showthread.php?t=1096303But it is a worry - the whole issue of lockouts worries me and I'm not happy about the number of problems I've heard of. It would be good for the guys who've had lockouts to post their info on these threads so the manufacturers and general community can get a picture of what's going on.
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Post by sean on Sept 5, 2009 10:27:09 GMT 10
Thanks Andrew, I'll take a look. For the record the only time I've ever had a lockout or even a single glitch on 2.4 was with the AR500 in my Blaster.
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Post by sean on Sept 5, 2009 11:00:44 GMT 10
Just had a look at those posts, and neither shed any light. The first is related to DX7 range issues so I don't know if it's appropriate to post re my lockout. The second is a just bunch of arguing between those who've had problems and those who haven't!
My personal view is I'm happy to stick with Spektrum but I'm going to be ultra careful how I setup the rx - ie perfect antennae alignment (ideally with antennae outside the fuse), I'll always use a good 6v battery, and I'll stick with the better receivers.
The number of recent 2.4 related problems is a big worry, but to be fair I have seen a lot of people crash thanks to problems with 36MHz gear.
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Post by thevon on Sept 5, 2009 12:38:14 GMT 10
Ta. It just worries me that there have been a few of these where there is no suspect or confirmed diagnosis. I have had lockouts on 36meg, but there's usually some sort of reason, eg shootdown, carbon blocking aerial, weird Bald Knob interference, Rx reception problem later detected in range test, etc etc. And with 2.4 the lockouts that you guys have reported have been total and irreversible, whereas with 36 there's usually a transition to glitching before total loss of control, and often you can recover the situation. The only total lockout I've had has been battery shorting.
Therefore with 36 meg problem's you're usually left with something to learn from and try to avoid in future. What worries me with the 2.4 lockout issue is that so far nobody seems to know what to do to avoid it. Sticking to the big name brands is good advice, but I'd like to know what actually goes wrong before I switched to 2.4.
On a side note, I've had just about every type of interference problem known to man, using 36meg. But I don't think I'm exaggerating to say I haven't ever had one glitch since I switched to the Multiplex Cockpit and using the MPX Rx's too (on 36meg). I had some glitches using other receivers when range testing the MPX on the ground in high RF areas, but once up in the air all is OK. Twice I've stupidly launched without extending my aerial and it's amazing what range it flies to before I realize there's a problem!
It was a very different story when I was using the Hitec Optic 6, and Hitec receivers. Lots of problems all the time. What I'm saying is that if I HAD switched to 2.4GhZ and got the improvement and reliability that I'm now getting with MPX, I'd be a total convert to 2.4! Fingers crossed, but the reliability I'm getting is THAT good!
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Post by sean on Sept 5, 2009 12:56:47 GMT 10
While I'm happy to stick with Spektrum, my personal feeling is Spektrum 2.4 is too susceptible to failure if your radio install isn't perfect. The other thing I don't like is when it loses the link - it does it in a big way!
Also I don't think you can go past the fact the short antennae are easy to block with a carbon part even if your plane is mostly glass or another carbon friendly material. The solution is to use an rx with multiple receivers, as is the case with all the more expensive Spektrum recievers.
With my Blaster crash, I had a gut feeling that I'd cut corners with the install (4 cell battery and antennae were just shoved in and not 90 deg to each other), plus I had a feeling the rx had been acting strangely. In retrospect I could have avoided that crash if I'd been a little more careful.
I don't hear of people crashing on Futaba 2.4.... that might be because hardly anyone uses it, or it might be a better system.
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Post by ezza on Sept 5, 2009 13:20:45 GMT 10
I had never heard of a Futaba lockout until Tims' Tragi the other week. His was the full range, Fasst system. Worst thing was it locked out when it was only 50m away from his Tx. It went into ds patterns, so every concievable angle between Rx and Tx, made no difference. After about 15seconds he regained control for a second, and then it dropped out again. He had one antenna running backwards and one forewards, and had flown the Rx in all his other planes no worries. Nose cone is glass but he had painted it. Not sure if that is a problem? When we got to the wreckage everything worked perfectly. Then later in the day he put the Rx in another airframe and had no problems. He took the Rx to a guy who had a tester and there were no concievable issues. Tx antenna was checked, battery pack fine, no dodgy leads, etc,. Final guess was that it was a blanket outage of 2.4??? Still guessing really? Couldn't believe how it happened when he put it into his first expensive 3m ship. Very unfortunate. I have to agree with Andrew on the multiplex gear. I have had two issues with their Rx's. Both were channels that didn't work, straight out of the box. I sent them back and all fixed for free. I think I was just unlucky. Never even had a glitch so far.......touch wood. Multiplex stuff does seem very good. I always loved the Jr RS70 Rx, but did find an occasional glitch with heavily carboned planes. Still have several in most of my airframes, but now switching to Multiplex IPD for all future builds. Eric
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Post by sean on Sept 5, 2009 14:08:49 GMT 10
Bummer! I didn't know Tim was using Futaba. That is a concern. It is suspicious that it was OK in other planes but not in the Tragi.
When I crashed the Blaster it spiralled into the ground so you'd think if it was a blanketed antenna it would have rotated around to give a good signal. As with Tim's crash everything was fine again on the ground. When range testing the AR500 afterward I found when I got to the extreme of range and it lost signal, the time it would take to regain signal was quite random. Sometimes it would be instant, sometimes it took several seconds. Several seconds is enough to lose a fast plane from a pretty decent height.
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Post by thevon on Sept 5, 2009 16:59:30 GMT 10
Ken just came down to have a fly at the Wreck, but the wind was too west. Bummer.
Wow, that is a worry. I wondered whether Tim was on 2.4. And Futaba is the one Ken was saying was probably the most reliable! Aaargh.
Ezza, me too with the JR RS70. I have had 2 instances (one at Bald Knob and one at The Wreck, Woody Point) where range checking failed with them failed and I replaced with a MPX IPD Rx on the spot, and had perfect results.
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Post by skyboyken on Sept 5, 2009 21:44:48 GMT 10
Wow Ezza,
I thought Tim was a Spektrum user?
With a FASST system, the only 2 questions I can think to ask are:
1. did he do a range check before flying, turning the plane in all orientations to the Tx so as to check for range and blanking?
2. How old was the battery pack?
I do know that FASST can have issues with a too-low voltage. All 2.4 systems can (they're all digital). It's just that FASST seems far more tolerant than Spektrum in this regard.
FASST is frequency hopping and spread spectrum, so it is basically impossible to jam unless someone is willing to spend a lot of money and go about it deliberately, or unless you are flying in the centre of downtown Sydney. I know this is a generalisation but I used to do this (jam signals etc) for a living so please take it at face value for now.
I still say that FASST is the most reliable 2.4GHz system on the market. I've done a lot of research before saying this, and I say it based on user reports from the US (lots) , UK (some) and Germany (only a little) as well as on a technical assessment of FASST.
I know for instance that the US and UK guys flying giant scale aerobats with huge metal engines and some carbon are having no blanking problems with FASST receivers (which don't have satellite receivers). Unless Tim didn't get a good range check or unless his paint contains something which absorbs or reflects radio waves the likely culprits are a battery voltage drop for unknown reasons or a faulty Receiver or Transmitter.
Guys, there are lots and lots of pilots all around the world flying expensive planes on 2.4GHz and having no problems at all. I am certain that we will find over time that nearly all the unexplained outages are voltage drop issues, and that once we start doing the right quality of power supply (battery choice, wiring and installation) we will have bulletproof 2.4GHz systems too.
I can't say often enough that momentary and intermittent battery voltage drop is BY FAR the most likely source of any problem with any brand of 2.4GHz system. My personal recommendation is to use a new 5 cell Eneloop pack or 2 A123 cells on any plane you care about, and charge Eneloops at no more than 600mAH. I do this and I also use an LED voltmeter fitted to the plane so I can have a check every time I turn the plane on. This has already saved the Caracho for me once. They cost about $6 from Hobbycity. The big one is that if you don't put a new receiver pack in a 2.4GHz plane then you are playing Russian Roulette, simple as that.
Of course, double and triple check all the wiring and any switches too. I had a chat with Greg Roper today. He bought my Xperience Pro, and when he took the fuselage servos out he found a power wire pinched under one of them. It wasn't that way when I built it, so it has happened because of flexure in the fuse, probably on dork landings. There's another one to watch for.
Servo connectors on battery leads are a well-known source of intermittent contact, because individual connectors can easily slide backwards in the plastic holder. Of course Murphy would have it fail in flight and be fine after the crash when you're trying to figure it out. My plan from now on is to use 2 pin Mini-Deans for my battery connections, but be careful with polarity issues with these.
I have previously posted here about the French device that provides a fully redundant power supply for F3X models. I intend to be using it in any new 3m mouldie I buy, and I recommend it as money well spent. Astan I hope you read this!
From all the above I hope you are getting the message that there's A LOT of ways to get an intermittent voltage drop in our planes, and that both prevention and constant vigilance are necessary to protect your planes. So replace your receiver pack TODAY unless it's new, 5 cell and Eneloop or A123.
And get a decent charger while you're at it. One that has a discharge function so you can cycle your Nimh cells occasionally and easily check their capacity at least 6 monthly. I replace my packs before they get to 90% of original capacity. I use and recommend the iCharger range from Hobbycity. I don't recommend Swallow chargers because the Victorians tell me they put a high amp 40V kick into the pack at the start of the charge, and this can and does damage smaller packs and relatively high resistance packs like Eneloops!! Thanks Andrew for causing me to remember this by asking me about chargers today!
Signal blanking by metal or carbon is probably the next biggest risk. An all-aspect range check with any motor running is the recommended action for this one, and don't fly until it passes. Getting the antenna(s) outside the carbon bit seems to be the go for gliders, but always do a range check.
I apologise for the long post guys. I'm trying to help you save your lovely planes!
Go Great!
Ken.
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Post by ezza on Sept 5, 2009 22:01:24 GMT 10
Hi Ken,
Tim is a Futaba user and has not had a single problem before or since this incident.
1. Yes the plane was fully range checked.
2. It was a new eneloop pack(cycled 4-5 times). Immediately after the crash we hooked up the battery and voltage was good(can't remember for sure but 5.6 rings a bell), even when knocked about, etc,. However it was a 4 cell pack. I believe Tim has always used them and never had a problem before. Battery was tested the next day as well.
The lockout was so long(15 sec), and happened so close to him, it was strange.
Eric
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Post by thevon on Sept 5, 2009 22:31:56 GMT 10
Ken that's a great response, thanks. (for those who don't know, Ken's been involved as part of his MAAA role in reviewing 2.4Ghz systems and he has an extensive history in high-level radio stuff as a Navy radio tech).
I still feel some unrest about 2.4 because when you read the RCG posts it seems that there are a number of cases where experienced guys have been sure all their gear is right and they've had lockouts. Now I know that in such forums people tend to post their problems but not their successes, and also there's an over-representation of crackpots too. But my gut feel is something's going on and there's no cause/effect proven diagnosis yet. I do hope the definitive cause becomes clearer and reliable prevention becomes possible.
I guess in laymans language it sounds like glitching with 36 is like an AM radio - annoying static and crackle but you can still hear the music. Whereas 2.4 seems to be like a PC - a dip in the power supply shuts it down and the system reboots during which nothing works.
Ken the advice on the batteries is good. If it's the key issue then 2.4 is obviously far more susceptible than 36meg and the consequences far more severe. The marketers push 2.4 as being far more "idiot proof" than the old systems. But most of us guys are pretty serious about how we use our gear, and we've still had problems. There are a lot of guys taking up 2.4, and only a proportion would be willing or able to be as careful and rigorous in battery care as the 2.4 systems seem to require.
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Garth
> 100
wings are for wimps
Posts: 188
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Post by Garth on Sept 5, 2009 22:32:23 GMT 10
i use this for all my batteries. never had a problem Futaba BR2000 battery checker Price(each): $69.00 The BR2000 battery checker works on nicads or nimh. It utilises a simple push-button setup for easy programing. Its display shows input voltage, the current its discharging at and the mAhs it has taken form the battery. It inludes multiple leads for use with most batteries. To check receiver packs with the BR2000 Discharger/Cycler modelers simply connect the pack, set for 4.8/6.0/7.2V, and push the button. Red (Danger), orange (Caution), green (Attention) and blue (Safe) zones on the circular graph clearly indicate voltage status. Holding the button down for three seconds initiates discharge function, with a current load adjustable from 1-3 (slow to fast) amps. LCD display is backlit in red when checking; a blue backlight means discharging operation. A built-in fan helps keep the unit cool while discharging. Automatically shuts off when discharging or cycling is completed
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Post by thevon on Sept 6, 2009 7:07:26 GMT 10
A few more ideas being discussed in the RCG thread. Possibility that 1) a faulty servo or 2) battery in the way of Rx could cause problems, and some disagreement about whether microwave paths can cause lockout too (a definite issue at Bald Knob). www.rcgroups.com/forums/showthread.php?t=1106184The battery checker is a great idea Garth. So much better to check voltage under load. You can do it with a Swallow or similar charger by putting it on a discharge cycle and check the voltage, but your gadget is far more convenient.
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Post by skyboyken on Sept 6, 2009 18:24:56 GMT 10
Hi Ezza,
That's great info. For the record I haven't had any trouble on 4 cell Eneloop packs either, but 5 cells are good insurance for Spektrum users and anyone pulling high current out of the Rx pack.
So given the pack is a good one and obviously hasn't had a cell fail, the next place to look is at the wiring, the connectors and any switches. You're looking for an intermittent fault, which any tech will tell you can be impossible to find until it decides to show up while you're testing. That's why upping the standard of our wiring, switches and installations is so necessary - to avoid creating these terrible situations where suddenly the plane stops responding and afterward you can't see why.
Tim's crash is almost certainly the result of a momentary and/or intermittent voltage drop. It could be that a servo had or has a problem which caused it to draw such high current that the voltage dropped too far, to give another of the less obvious causes of such things.
Andrew,
I'm afraid I can't agree with your assertion that serious guys have been having reliable performance from their power supply system on 36MHz.
From all the talks I've had with all the pilots of moulded gliders, BY FAR the most common cause of a crash is power failure. So as I see it, the only difference between 36MHz and 2.4GHz is that on 36MHz the problems or potential problems we have built into our planes don't cause us to crash when they are momentary/intermittent. That probably just looks like yet another glitch. The plane crashes when it gets worse and goes off the air entirely.
In other words, there's nothing new here. It doesn't matter whether your plane is on 36MHz or 2.4GHz, it's going to crash when the power system fails to deliver. It just may happen sooner with a 2.4GHz system.
For me, I have no concerns whatsoever about the radio link between my Tx and Rx on 2.4GHz, so long as I don't fly in the centre of a major city and so long as I have satisfied myself with an all-aspect range check. I also have zero worries about getting shot down by another pilot. That's 2 BIG things less to worry about.
The power system worry hasn't changed as far as I'm concerned. It has just become more visible, which is a good thing (for the long run) except if it costs you a plane.
Ken.
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Post by thevon on Sept 6, 2009 19:34:09 GMT 10
Ken I didn't make that assertion.
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