I was up on my fourth flight of the day with my FourStar 40. I did a low pass downwind and pulled up at the end of the runway and got about 300ft up to do an immelman. Just when I was at the top of the turn when the plane was inverted and in a full dive attitude I noticed I lost total link with the RX because I had no control of any surface and it went into failsafe (I noticed that the RX cut the throttle as I have programmed in my failsafe mode). This lasted about 2-3 seconds but I cannot really tell, I was very nervous. I gave it full aileron to level it and it finally recovered link and it leveled but it hit some trees with the wing and I finally managed to land it fairly well in a tall grass spot. The plane is already fixed and ready to fly again but I'm now very paranoid as to what caused this glitch and want to be certain before I fly again. I must say that I've already flown this plane with this exact same setup for about 2 months and this is the first time I get some glitch like this. The antennas are set up per manual instructions. The only thing that makes me wonder are the issues related to these receivers (the infamous Futaba heat issue). The RX is strapped on top of the battery pack so it might get a little hotter than usual but it was 15°C (59F) that day, nowhere near the failure point that has been made public by several users for this RX even if the battery got unusually hot during flight. I also tested the power switch by wiggling it and so but I couldn't find any abnormal behavior. Also worth saying, the battery showed little discharge when I load tested it after the crash. This glitch happened as I was just on top of some minor power lines that sit conveniently at the beginning of the runway which means that everyone who flies at my field goes over that spot at least 20 times each flight and no one has had any issues that have been related to those lines (although some have crashed into the lines themselves but that's another story). Just so anyone who might be able to help, here's the complete setup: O.S 46AX, Futaba 3004 on all surfaces, Futaba 10C transmitter, Futaba R6014FS receiver, 1200mAh NiCd battery pack.


Any ideas? I don't want to risk this plane again.

hmm, receiver straped to battery pack... dont sound like a good idea to me[]

It's not the optimum setup but the space in the FourStar is really tight plus I've flown this plane exactly like this on much hotter days with no issues at all. The battery is wrapped in thick latex foam so the heat is rarely noticeable.

Might want to check in the radio forums, there were some things being discussed about losing link that I read, but I can't for the life of me find any now. One guy was discussing having a problem with a servo that would cause enough voltage drop to make the Rx reboot, or something similar to that.

Maybe some of the people that boast go 2.4 and you will never had another problem can help you. I know how you fill, I have thrown rec. and crystals away because of a glitch I could not explain.

Did you load test the Rx pac prior to your
4th flight ?

Bob

No, I tested it after the crash with all surfaces attached and it had plenty left.

I was thinking along the line of 300 mAh's per
flight time 4 equals 1200. JMO

Bob

I assume you checked the receiver battery with an expanded scale volt meter that applies a slight load? You may want to go even further and monitor the battery in action. Watch it while moving the controls for a while. Maybe even put a slight weight or other restriction on the surfaces to simulate actual flying conditions. Maybe you can catch the battery falling off under heavy load.

You may also want to check for voltage drop across the switch or connectors.

After an incident like you had, I personally wouldn't trust the battery, switch or receiver unless I found the exact cause.

I'm not sure about the drain that each flight takes from the battery although I've used it safely for 6+ flights of 10 minutes before and it would still pass a loaded test afterwards.

Yes, I checked the battery right after the flight with a loaded voltmeter and I moved the surfaces just as you suggested and it still had plenty of juice. I'm gonna get a new switch to take that out of the equation. I thought of cycling the battery with an Accucycle to see how much charge will the battery take but its fairly new (less than 6 months) and I'm very careful with my batteries so I wouldn't be surprised if the battery is OK. The RX is also new, it came with the 10C which I've had for roughly 4 months and has never crashed until this time. I don't know how to determine if the damage is within the RX.

I don't know if this all could be related to an odd servo issue I had two weeks ago. Its [link=http://www.rcuniverse.com/forum/m_8412574/anchors_8412574/mpage_1/key_/anchor/tm.htm#8412574]HERE[/link]. I must add that the servo I talk about in that thread has been tagged DAMAGED and is not on the plane any more.

I've just set up the plane exactly as it was the day of the crash. Here's a picture so if anyone has any ideas, pleas pitch in.

By the way Ken, Minn you're the knowledgeable guys around here, no ideas?

Thanks guys.

Have you tried doing a range check or anything like that to see if you can get it to reproduce the lockout?

I did just after the crash. I even had someone take the plane out far near the place of the incident and I stood with the Tx where I was standing at the time it failed. I couldn't reproduce it.

Just a thought. When that person was holding the plane for the range check, did you have them move the plane around in different orintations to the radio?

Yes he did, he's the field owner and instructor so he had that trick in his book.

I have no idea. I wish I could help. Is the battery fully connected, the switch working well, etc?? I mean, you'll need to check EVERY connection. Even from the wires to the little spikes (sorry I don't know the names) within the Futaba-J connectors. Those cause problems (not just Futaba-J, btw). A faulty battery connection will make you go to failsafe mode.

Another observation is that that is an incredibly powerful, expensive receiver for such a simple plane. Boy do I wish I had a couple of those to put in 4-channel planes! Nice set-up on your antennae...but I'd try keeping the bottom part of the antennae at 90* angles, not just the tips.

I have already tested the power connections and they appear to be solid. I will be replacing the power switch just in case. I use that receiver because it came with my 10C and couldn't afford another Rx so I guess its a little overkill but I can't afford any equipment right now. As you said, I've been experimenting in ways in which the antennae can remain completely extended but the space in that plane is tight. The manual specifies that the important part is the silver tip but it does advice not to turn the rest of the cable in small radii which I might be doing with this setup. Other user at the radio forum has suggested that I place one of the antennae upright in terms of the plane's orientation so I'll be trying to get that done too.

I think if the battery lost connection, it wouldn't go into failsafe. It would merely freeze the servos where they were. If the connection was in and out intermittent, it may go to failsafe since when you first turn on the rx it is basically in failsafe till it detects the tx.

But if the battery or any power connection is faulty and the power supply gets interrupted during split second but it then comes back, then the result would be those 2-3 seconds while the Rx locks the link again, wouldn't it?

I meant intermittent connectivity. If that were true, it could've pissed off the receiver just long enough for it to go into failsafe...and then he could've lost complete power and it would've gone in, in "fail safe" mode (or close enough to it). Plus, the immelman could've easily been what did the final "pissing off" of the battery cable. It's just an idea...I haven't heard any better ones yet!

PLUS what plugin said

We had a club member that was experiencing random glitches on 2.4. He finally lost a plane (never told anyone about the glitches till the plane went down). Turned out that the connection from the transmitter motherboard to the antenna was loose. It would intermittently lose contact, causing theplane to go into fail safe. This transmitter was relatively new, but I don't remember what brand it was.

Your best bet is to send the transmitter and reciever to Futaba, explain to them exactly what you experienced, and have them inspect.

Brad

What was suggested over at the radio forums makes some sense to me.



The [link=http://www.rcuniverse.com/forum/post.asp?do=reply&q=1&messageID=8465325&toStyle=tm]thread[/link].

I wish I could do that but I'm located at Bogota, Colombia, South America. The shipping costs would come up to the price of a new Rx.

This problem could be in the switch. I have seen vibration cause a switch to make intermittent contact. Turn the plane on and tap on the switch housing. See if you can make it jump.

David