kthmarks

Both my father and I have DX-7 systems. We both experienced loss of signal while flying on Fathers Day. And both lost our planes. Both planes were in relatively the same area of the field and both lost aileron control. His is a DX-7 TX with an AR6100RX, mine is a DX-7 TX with an AR7000 RX. I did not check his battery condition after the crash as he was flying an electric. My batteries however were in good condition. The RX was a 5 cell 2000 mah that read 90% with a 300 mah load. The TX was at 10.3v.

I know of one other person who lost signal that day using a DX-7 but am not aware of his circumstances. In addition there were two other pilots who lost signal on non Spektrum systems that morning.

Below is a link to our flying site. The incidents occurred directly north of the west end of the runway perhaps 200-300 feet at pattern altitude.


Needless to say, we're both concerned and are looking for advise.


http://maps.google.com/maps?f=q&hl=e...,0.011673&z=17

krayzc-RCU

My Feedback: (31)

wow it seems every week someone is going in let along the people who don't read these forums who don't have a voice...

teryn1

My Feedback: (77)

So, would we be seeing this post if this accident happened with your 8103 or 10X? Probably not.

krayzc-RCU

My Feedback: (31)

the difference is with your old radio you know why you wrecked,
ie dumb thumbs
lost a crystal
turned on by someone in the pitts
battery faliure


to many post were people just don't know what happened, yes it can happen with any brand or style of radio but u be your own judge....

post from some were else:

Well guys here's how today's maiden flight went. NOT TO GOOD!!!!!!!!!!!!!! All range checks exceeded stated minimums. The plane took off beautifully. Nice and level up to about 15 feet then it went into a high rate left roll and plowed into the ground. We don't know what caused it at this point. I'll have to send in the equipment to see if there is a failure of some kind that will explain it. CRAP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I'll let you all know what I find out.

rino

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rino

My Feedback: (121)

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JCINTEXAS

kthmarks,
Do you think there is a problem with the 2.4 GHz radio that caused the crashes? With all the 2.4 GHz phones which are widely used, if this could
cause interference problems? Also, some microwave towers operate on
2.4 Are you hearing about other problems like this around the country?
Perhaps there is a problem with the frequency? If so, we all need to know
about it now and so do the radio manufacturers.
Regards
JC

teryn1

My Feedback: (77)

You need to research and LEARN how the technology works. Yes, it takes effort and is hard but it will benefit you much more than posting these kinds of things here.

kthmarks

I was under the impression this was a forum to get advise and direction from the manufacturers rep. Which is what I am hoping to do. I do not know how to take a few of the responses above but I anxiously await comments from Danny.

dsnyder

What exactly happened when the incidents occured? If you suspect the system, please send them in for a check up.

kthmarks

Danny,
Thanks for your response.
We have not been in RC long so I appologize in advance for not being very knowledgeable on the subject.

Both incidents occurred at the end of the down wind leg about to make a left base turn for final. So, straight and level when they rolled. One into the ground, the other was recovered briefly, made final approach then rolled into the ground on final. There was undoubtedly interference that day because there were non spektrum radios having issues as well.

The power company recently installed high tension power lines not far from the field. Would this have have a negative effect on our reception? I assumed with the binding capabilities of the Spektrum system that it was a remote possibility of interference. Is there anyway to know for sure? I read once about a devise called a "snitch". Would that help to find out if and how much we're being affected?

Newc

Keith -

I'm curious about what you meant when you said Does this mean that the voltage was reading 5.4 volts (90% of 6.0 volts)?

kthmarks

Voltage is what I was referring to. The checker I have will show a 5 cell, 6v battery @ 100% = 6.42v. 90% = 6.3v, 80%= 6.19v, etc. It's an Expert V300.

colecaz

I suggest you get an AM radio and walk out to the area of the crashes. Turn the radio to an unused spot on the dial and listen to it. Do you hear any "frying" or "popping" sounds. Walk away from the area while listening and see if the sound changes. If you get loud static or "frying" noises, contact the power company and tell them what you found. Ask them to make an "RFI" (radio frequency interference) survey of the area to see if the power lines are generating the noise. Loose or intermittent electrical connections can create all sorts of interference, even up to the the 2.4 GHz range. Not often, but not impossible.

If strong enough, interference can overload a receiver and desensitize it to the point of loss of signal, even if the interference frequency is far removed from the receiver frequency. Since you had both 2.4 GHz and 72 MHz plane go in, overload is the first thing that comes to mind.

You might even see if your cell phone works in the suspect area..

rino

My Feedback: (121)

I've actually had EMF fry several 72 Mhz RX's from high-tension lines. You have to get pretty close though for this to happen.

pepatrick

I fly at the same field and had 4 flights this Saturday (23rd) on Spektrum and did not have a single problem. GMA field has not really been known for interference. I was a little concerned about the power lines, but have not had any issues with them. They have only been up now for a couple of months, but have not seemed to cause a problem yet.

dsnyder

Power lines should have no affect on system performance.

kthmarks

I know the things that happened that day we caused by something. I have not been flying RC long enough to have a feel for what a reasonable failure rate is for batteries, airframes, etc.

I suppose all we can do is keep an eye open and monitor the frequency of these occurrences and see if there are any trends that develop.

Thanks

vanguard

My Feedback: (25)

Woukd be nice to know what kind of planes they were flying. It almost sounds like it could have been a plane problem rather than a radio problem. If they were flying too slow when they made their final turn they could have easily given too much elevator coming out of the turn and caused the plane to snap/roll into the ground. Since they stated that they were relatively new to the hobby they may not have realized exactly what led up to the crash.

jetstuff

Yep...that sounds more likely....there are many reasons why models crash........nearly all of them pilot induced [] either through incorrect installation, (airframe or radio) or incorrect application of appropriate Tx stick command. Properly installed, radio failure is the least likely. Interested to know why you feel the need for 6.0Volts to operate an aeroplane though.....or does the 2.4GHz need it?....... JR Rx (and many servos) are designed for 4.8V I believe.
Been doing this sport for about six years this time around....and crashed many times...but never through radio problems.... be more self critical.......happy days[8D]

John

Tired Old Man

My Feedback: (1)

If you went below the rated voltage of your battery pack you have a great place to start looking for a cause.

kthmarks

Novice or not, planes that roll by themselves during straight and level flight is either airframe failure of some type of a glitch in the radio signal.

It's easy to be an arm chair quarterback and blame these types of things on pilot error when you weren't there. But believe me when I say, the same appx. location, two planes, straight and level attitude went crazy. As did several other planes that day.

The reason for my post was to ask Danny the possibility of interference and if some type of device (a snitch) could help us determine if newly erected power lines could be contributing to our problems.

I believe he answered my questions and at this time I would like to close this thread.

vanguard

My Feedback: (25)

Usually the first thing heard when a plane crashes is "I got hit" be it a novice or experienced pilot. Done it myself so believe me I know. Our field is located right next to a line of high voltage/tension lines and we have had no interference on FM or 2.4ghz.

kthmarks

Just to keep up......we lost another plane this past weekend (7/15/07). The same place, almost exactly as the other two. This one we were not able to retrieve as where it went down was an area that is so dense in trees and underbrush we could not search thorough enough. Or, it went down across or into the stream.

For those of you who have said it's pilot error....I don't think so. Three planes down in the last two months, same place.....no way. It has to be radio interference.

Nathan King

Just my .02

Yes, radio failure is erroneously blamed for pilot error ~90% of the time, but I highly doubt this was caused by multiple instances pilot error. Besides the great coincidence, when an airplane stalls it acts very different than if the airplane suffered radio failure/interference. You can almost always "tell" from the discreet visual clues, even when watching someone else.