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LT-40 large silver window sticker have metallic ink on it? Radio glitches

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LT-40 large silver window sticker have metallic ink on it? Radio glitches

Old 08-24-2017, 08:49 AM
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Ghia
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Default LT-40 large silver window sticker have metallic ink on it? Radio glitches

Im having radio glitches in this plane that Im trying to sort out. Im a LONG time RC heli pilot but never soloed a rc plane before, so i built a LT-40 from a kit and trying to get it flying reliably. i have had quite a few radio glitches so far. I have in this plane:

Futaba 9C radio
XPS 2.4ghz 8channel rx
dual A123 6.6v 2300mah RX packs in parallel
$10 hitec servos
webra 55C heli engine

My radio brand offered me great support and asked about any metallic stickers?? Im not sure on that as its a Sig factory sicker! They said move my RX as servo conrods/ moving servo wires around the RX can detune the signal in flight causing glitches! My radio failsafes are set to: elevator up, rudder left, and engine to idle upon signal loss. I have moved my rx to new location as high up in the plane as I can (RX antenna almost touching roof now) and I will secure ALL wires so no movement in flight. I havent flown these changes yet. new pics here:
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Last edited by Ghia; 08-24-2017 at 09:09 AM.
Old 08-24-2017, 08:53 AM
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Ghia
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Here is a video that Im glad had this plane on buddy box with a instructor that day!

Old 08-24-2017, 10:19 AM
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Hydro Junkie
 
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Okay, where do we start?
I know tech support is trying to blame the metallic window stickers but I'm not totally buying that since we use metallic paint on scale hydroplanes quite often without issue. Also, was the plane's orientation to the transmitter the same every time it glitched? If the whole plane was covered with the metallic covering, then I might say they have a point but if it's only simulated windows, I'm not buying it
You said you are using a Futaba 9C, who made the 2.4 module you're using? I have a 9CAP myself and it's never glitched using a 75MHz module and 168DP receiver
What are you using for pushrods?
Was the antenna anywhere close to servo leads?
What way was the antenna pointed in relation the the receiver and airplane? Was it sharply bent, slowly curved or straight?
Old 08-24-2017, 10:28 AM
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Hi!
The sticker isn't the problem!
The problem could be the servos that cant cope with the high 6,6 voltage from a LiFe 4 battery or servos with worn potentiometers.
Question...Why using such large batteries and in parallell?? A single 4,8V-6,0V battery (NiMh) of 1500-2000mAh is enough for many 10-15 minute flights.
Old 08-24-2017, 11:00 AM
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I run a 1/8 scale unlimited hydroplane for three to 6 heats of roughly 5 minutes each on a single Futaba 4.8 volt flat receiver battery pack and that's running two power hungry digital servos, one of which is a high torque type. That has me thinking something else:
How are your battery packs secured inside the plane?
Since Jaka brought up battery output, let's take this a little further. What actual servos are you using? Telling us you used $10 Hitecs is like saying "I drink cheap wine", giving us nothing to go on as far as what the servo can handle.
I wasn't able to tell what was a glitch and what wasn't in the video. The camera wasn't always on the plane so knowing what the plane was doing was just guesswork as far as I'm concerned

Last edited by Hydro Junkie; 08-24-2017 at 11:05 AM.
Old 08-24-2017, 02:29 PM
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Ghia
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Ok first it flew with RX and wires like this in that above glitch vid. I have hitec hs311 servos all around:

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Then I rotated the RX and cleaned up my wires mounted batts under fuel tank and flew it like this pic:

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That hellish flight was almost its last! Plane still glitched/ failsafed 3 times. Damn! I thought i had it fixed!

I fought it each time with my failsafes trying hard to lose altitude and crash me each glitch! My instructor Brett couldnt get my neck strap disconnected so he asked to fly it and just stepped in, grabbed my Tx, and pulled my face over his shoulder and landed between glitches! We was two grown ass men standing WAY too close to each other!

I cant thank him enough though for doin what was needed to quickly save my plane! My nerves were fading fast during that flight and i have never landed a rc plane before! I had sure had a few heart attacks during that last flight.

So now IM totally moving my RX to my first post post(radio system is XPS) and will change out RX. I dont think its futaba 9c as its rock solid 10+ years in my large helis. I used parallel packs as I needed nose weight and figured more flight time instead of lead weight and redundancy. I appreciate any help as it has been quite a ride! I will solve this though!

Last edited by Ghia; 08-24-2017 at 02:45 PM.
Old 08-24-2017, 05:18 PM
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So who's transmitter module are you using? If it's not Futaba, I'd get one AND a Futaba receiver compatible with it. After what I just found, I'd trash the XPS stuff really quick. Here's a cut and paste of what I found:

Why some XPS users are hopping mad

WILL IT OR WON'T IT HOP?

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This article was written before XPS effectively conceded that its system was insufficiently frequency-agile to cope with real-world interference.

The XPS system now appears to be as good as any and better than some - but I'm leaving the following online to act as a piece of history.

ORIGINAL ARTICLE

When the XPS module-based 2.4GHz system was announced there was a flurry of excitement.

In fact the claims being made for this revolutionary system were almost too good to be true.

Not only was it compatible with virtually every RC transmitter on the market but it would provide all the benefits of other 2.4GHz systems and more.

Telemetry, a 5-mile range, the ability for thousands of systems to all run simultaneously without interference -- these were just some of the bold claims being made.

Well after almost 18 months some of the long-promised features still remain undelivered but in the meantime many model fliers have been using XPS without problems.

Unfortunately a growing number of formerly satisfied users have also suffered from unexplained crashes in which their models stop responding to the transmitter. XPS has pointed to a number of possible causes for these crashes and in a number of cases the problems were proven to be caused by poor installation, faulty batteries and other factors outside XPS's control.

But recently a number of people (including myself) decided to put one of XPS's more important claims to the test -- it's claimed ability to hop away from potential interference by automatically changing its frequency.

Despite the best efforts of myself and several others, there is no evidence that the XPS 2.4GHz system is able to change frequencies once it has been turned on, and that's worrying more than a few people.

For their part XPS now claim that their system will only hop under very specific circumstances - which must be even more worrying since those conditions represent a very tiny range of possible interference types.

Whereas Futaba's FASST system is constantly hopping and therefore remains almost unaffected by interference that can cover as much as half the 2.4GHz band -- and Spektrum/JR operates on two widely spaced channels so as to have some backup if one of those channels is hit by interference, XPS has no safety net.

It could be that at least a few of the mysterious crashes attributed to XPS are due to this lack of safety net. If a burst of strong noise does happen to appear on the channel XPS is using the system appears incapable of sidestepping it in the way JR/Spektrum and Futaba do.

Naturally this situation has left some XPS users hopping mad.

When they bought their systems they did so in the belief that it would automatically change frequencies to avoid potential interference and now they find that even XPS themselves can't provide testers with a scenario where this happens.

In my opinion, anyone considering the shift to 2.4GHz would be well advised to stick to either of the big-names in the industry. The claims being made for these systems are well proven and both appear to offer higher levels of resistance to interference than XPS.

The best analogy I can use is to suggest that XPS is like a fast car without seatbelts or airbags.

So long as you don't encounter some unexpected obstruction on the road, you'll never miss these safety devices but sooner or later, many people will find that belts and bags can be a lifesaver.

And so it is with 2.4GHz RC systems. If you never encounter any significant levels of interference on 2.4GHz then your XPS system will likely work as well as those from Spektrum/JR and Futaba. However, if interference does appear, the big-name systems have an inherent ability to dodge what XPS can't.

Your choice.
Old 08-24-2017, 09:08 PM
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Ghia
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Thanks Hydro I have seen that article and its very outdated. Xps has been a full hoping system like FASST almost 10 years now. here's what Xps said about that article many years ago. https://www.rcgroups.com/forums/show...06&postcount=1

i have been flying xps in my helis for years with never a glitch. Im doing something wrong in this plane as it my first I believe. I dont think its the factory Sig sticker being metallic causing my glitches either, but I was curious. I have moved my RX location up high and away from metal/wires. Next I will install a different RX and I have ordered a hitec A9 radio after 15years of solid service on the front lines my 9c might be the prob though it looks solid as usual. Before I fly this plane again I will do extensive range check.
Old 08-26-2017, 07:16 AM
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Extensive range checks before flying are a good idea anyway. Had you done that with this one, you'd likely have discovered the problem on the ground. I'm not saying that to beat you up mind you, just to communicate best practice.

I'd be leery of that receiver because it doesn't have dual antennas.
Did you happen to notice if the glitches happened with the plane in a certain attitude relative to you? With that single antenna pointed up, its weakest reception will be when the plane is banked either toward or away from you.
I'm curious if you've used that receiver successfully in anything else before? Has it been in a helicopter and flown successfully?
Have you flown other things with this radio since these problems started?
Has this receiver ever been in a crash?

Your setup looks fine overall. We generally want receivers as far as possible from servos or any long, straight metal pieces. Yours looks as good as any of mine.
Old 08-26-2017, 10:19 AM
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Hi!
The first thing I would do is to change the battery pack to a 4,8V 1500-2000 mAh NiMh battery!
Second; replace the servo/servos that glich!
Old 08-29-2017, 04:18 AM
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Hi Ghia, I like the way you bundled your servo leads using a tie inside a piece of fuel tubing. I'm Gonna use that technique from now on.

Calvi
Old 08-29-2017, 03:00 PM
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Looking at your set up I see one potential problem. It looks like your throttle cable could hit the ELEV pushrod under certain conditions. The piece of foil on the window is not the issue on it's own. The RX is where I would start. I have seen servos cause a hit under certain conditions but not on modern radio gear. You might also wire around the switch for one flight to rule it out.

David
Old 08-30-2017, 05:08 AM
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Its a process of elimination lots of reasons you can get a glitch even with today's radios. I had a model that would go into wild gyrations for no apparent reason after many years of uneventful flying with the same gear. It traced down to a broken wire on the throttle gimble in the transmitter. First bind a different (known to be good) transmitter to the installed receiver. If it still glitches install the matching different receiver. If it still glitches chances are the installation of the other electronics in the model is the problem. Each time you make a change that does not solve the problem leave it in place until you find the problem. Then reverse the order and reinstall the original equipment checking for glitches each step of the way.

In the model I would bypass the on/off switch with a short aileron extension.
Try a different battery pack 4 or 5 cell nicad or nickel cells.
Unplug one servo at a time but plug in any good spare servo to give some type of load to that port.

In earlier days with am and later fm and narrow band chasing down glitches especially with early gas motors was a sort of black magic and guys worked out a variety of methods that seemed to work. This is what worked for me then and what I like to use even today. I can only hope it helps

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