Yesterday I was flying my trainer, and I was gonna land cause the batteries was getting low (known i had enough to land with). Then I gave ailerons to turn to land, but the plane just keep flying nice and level. Had no ailerons, elevator, or throttle. Then it got to a point where I got the plane back under control. landed it fine.

Couple of months ago my dad was in a slow dive and went for a little bit in the dive. Then he didn't have it under control. The plane started to spiral and started to level out then after a couple seconds the plane got back under control. landed fine

Last week I was flying and I was in a same maneuver my dad was, but i was closer to the ground. Didn't have it under control. Then it was in a death spiral and all i could do is pull up and it finally let me have a little control of it before it kinda nosed it in.

But what could it be bad radios systems or interference cause i haven't seen anyone else have problems. just with us and channel 54.

Nathan

And how did you KNOW you had enough battery power to land with? It only takes a couple of seconds for a load on almost-discharged nicads to drop them below operating volatage. I'm gonna vote for flying with not enough battery power as the first reason for your and your dad's problems. Another POSSIBLE reason is your radio (you didn't say which one you had) went into fail-safe because of interference. That's why I don't use fail-safe, you lose all control for a few seconds. The plane will usually fly through intermittent interference. Constant interference will crash your plane in any case, fail-safe or not. A third possibility could be you flew your plane directly off the tip of the TX antenna for a few seconds. The RF signal is weakest in this position. Low batteries would complicate this situation.

Dr.1

have you checked your crystal in the receiver to make sure it is not loose? make sure the antenna on your transmitter is tight and out all the way. all connections clean?.
If this happens again ensure the antenna is longwise to the airplane, the signal is transmitted from the long side of the antenna and not the tip, normal tendency is to point the tip at the airplane

The battery on the TX was like 9.8 and i usually dont fly under it and thats where it was. It has be lower then that before but just to be on the safe side. On pointing the tip of the antenna, i usually have it straight out from me and just turning my head to follow the plane. When it happened the plane was about 60 degrees with the antenna on my right side.

nathan

But what was the voltage UNDER LOAD on the RX battery?

My vote stands - low battery.

Dr.1

I'll vote for radio hits.

I've had the same thing happen on several channels when a local pager tower starts yapping.

Either I'll loose all control for a few seconds, or the plane will violently change attitude.

For me this primarily happened with Single Conversion 72mHz RX's.

Switching to Dual Conversion, even using the same frequencies, eliminated the problems.

Low battery. Just because the tx has a certisn amount of voltage does not mean the rx is OK. They are two different battery systems and have no relation to one another. The meter on the tx is not a indicator for whats in the rx batt.

TX battery voltage is no indicator of RX voltage. Most TX batteries will last much longer than "stock" RX batteries that come with most systems. You can ONLY rely on an ESV or voltwatch type check of the RX battery. You were VERY lucky to get your plane back down.

My vote: low RX battery or defective RX battery with intermittant connections internally.

the RX only had 2 flights on it. but if the RX battery was low or close to being dead, the plane wouldn't come back. but i know for sure that the other 2 flights were full charge.

but there is about three towers around where we fly and 2 of the stories i told in the first post was a tower. no one knows if they still work since we fly in a proving grounds that close a while back.

if you guys still say low battery I'll start charging the batteries after every 2 flights.

Ok, I'm a bit confused here. When you say you and your dad had the same problem. Were both of you using the same radio/plane? Or were they two different radios???

Ken

I'm glad you got your plane back safely. You did not say what size battery or how old the battery was. Have you cycled your batteries, lately?

To be on the safe side, the next time you go to the field make sure you remove the battery from the charger just before you go. Check the voltage.
check again at the field when you arrive and after each flight. Don't fly with less than 4.6 volts on a 4.8 volt battery.

I had an Alpha Hangar 60 with 4 servos, 4 channels. I was using a 600 mah 4.8 volt Nicad battery. I could get 4 flights. When I got home I would
charge the battery and I usually put in 200 mah. Another words I was averaging 50 mah per flight. Each flight lasted an averay of about 10 minutes.

Batteries do get old and begin to lose their capacity.

It could have been some type of interference, but I lean towards the battery.

Good luck. When you find out for sure, (if you ever do) what the problem was, be sure and post the cause.

Good flying!!!

A typical 600mAh battery will last a good bit longer than 2 flights.

I change these out for at least 1200mAh or 1400mAh batteries at the least and fly well over 14+ flights a day at the field on a single plane...

Your description indicates recovery after a few seconds of "glitching"... again something that I have seen thanks to local transmitters. These transmitters are 4 miles from our field and transmit on a different frequency that 72mHz we use...

But there are "harmonics" that can upset the RX...

The funny thing is a radio scan with a frequency checker ( with the extension antenna ) shows nothing!

However the "hits" have been very real.


At first I thought the same as others have suggested, that it may have been due to some other cause... that is until my flights were seen by a couple of our most experienced members... all three immediately said "radio hits".

What type of radio RX are you using?

Single Conversion? Dual? etc.?

How is the antenna set up on your plane? Do you have it fully extended? Folded back? Outside the plane? etc.?

Do you have the crystals in your RX "padded" or with a guard of some sort around them to prevent them from creeping out due to vibration?

Do you have a metal linkage connecting the throttle pushrod to the engine? This will cause interference.

Does your antenna wire CROSS servo wires or is wrapped around or very close to the servo or other wires in the plane?

my dad and i got 2 different radios but same channel and different planes. we have had the radios for a couple of months i got a hitec optic and my dad has a hitec laser 4, both radios came with a 600 mah battery. but with all the wires and the antenna are good says the guys at my club. the antenna is out side of the fuse in all the planes we have. every time we lost control of the plane nobody else was looking to see it. but the batteries hasn't been low to many times.

If you asked me 6 months ago what I thought about Hitec I would of told you they made great radios,but today I wouldnt recommend them to anyone. I purchased an Optic 6 last October and it worked fine until March. I landed my plane and the engine died and when I went to pick it up all control surfaces were shaking. I carried it back to the pits and it was still chattering (The transmitter was still on). I sent it back to Hitec for repair and they sent it back 2 weeks later saying it was repaired. I took another plane out did the range check everything was ok. I took off was flying around and after 5 minutes the plane flew away. When I got home I set up another receiver and servos and checked it out and after 5 minutes it stopped working the display was still on . Sent it back to Hitec and they sent me a new transmitter. While the radio was being repaired the 1st time stupid me I went out and bought a an other one. Well about 3 weeks ago I was flying around and the plane stopped responding and went in. At 1st I didn't think it was radio problem because when I picked up the pieces the needle vavle was missing and I thought maybe I had lost it flight and the engine died causing it to crash; the plane was a little heavy and you had to fly it all the way down, it wouldn't glide. Last week I was setting up another plane and notice the servos shaking, To come to find out if you tapped the back it would cause all kinds of h*ll. I checked the transmitter with the module from the other tansmitter and everything was fine. I called Hitec this morning and told them the problem and they told me I needed to send in the Transmitter with the module because they have to change the back case. Since I have to go to San Diego tomorrow I'll just drop it off in Poway.

Ok, if this is happening to two different radios then you need to find the common denomenator. The only real possibility is that there is some source of interference in your area. Especially since both radios are on the same channel.

Ken

There might be a minor technical issue with the Optic 6 that I haven't read about yet. I have been using one for two years now. It includes the Spectra Module. I have noticed on occasion during ground checks that tapping the module on the back of the transmitter caused intermittent radio glitches. The cause turned out to be loose contact on the pins that connect to the Spectra module. Cleaning the pins and just slightly bending them toward the top of the radio increased the contact in the module, and the problem went away. This may be the modification that Hitec is making to the back of the case. I have been alert to this possibility, and include it in my ground checks each day, and the problem has not resurfaced.

Brad

I have a bunch of HiTec RX's...

All function w/o problems.

HiTec includes a little anti-vibration cover with the RX's to cover the crystals.

Using these is a must.

The use of a HiTec RX radio system is not the problem.



CherokeeFlyer you are getting radio interference.

Which model RX are you using?


Have you tried changing to another channel?

There is also a real possibility that your batteries aren't fully charged as you think. You've not mentioned much about your charging or your batteries.

Are you charging them with the supplied wall wart chargers?
How do you know when the RX batteries have a full charge?
How long do you charge the batteries for the airplanes and when do you do that?

Most of the inflight symptoms you describe sound like loss of battery in the airplane or possibly as loss of signal. Interference from other transmissions will usually cause lot's of response from the airplane. You can actually see for yourself what might happen by checking with your equipment. Turn on both TXs and airplanes at the same time. Watch the two airplanes while you both work your sticks. This exercise isn't going to tell you much beyond what happens when there is interference, but it's worth seeing.

It's fairly easy to work out a few things that have not been mentioned.
Right now, you need to test your RX batteries to find out how long they last when you think they're fully charged. It's an easy test and certainly worth doing to possibly save destroying your airplanes.
1. Start off by checking the airplane batteries with an ESV. (You do have an ESV, right?) Write down the readings.
2. Start your watch.
3. Turn on the airplane and the TX. Work the sticks for 10 minutes as if you were flying. Turn everything off.
4. Check the airplane batteries with your ESV. Look at the TX meter. Write down the readings.
5. Repeat 3 & 4 until either a TX shows less than 9.6 or an airplane battery shows less than 4.8 volts.

Now, you know whether or not you've got a battery capacity problem. Until you do that, you really don't know some of the most important things to know.

well alright guys i went flying with my new plane, was flying pretty good. flew 2 times and charged the batteries (didn't get the batteries charge to full Saturday night still working on getting the servos in and lined up). fueled her up after charging the batteries took her off. was flying pretty good , then the engine dies, i was gliding it in, only had to turn a little bit to line up for the runway. and as i was lining up for the runway. the plane started rolling like the other times i said to you guys. well the aggravating part the plane crashed, it happened in the same spot the other plane crashed, and it was pretty close to the same time periods to. the plane was flying good without any glitches. batteries full charge.

any ideas?

nathan

We're trying to help you. It would help us to find out how you know you have a full charge. Charging the batteries after every 2 flights isn't required for flyers who're familiar with how to estimate the capacity an average flight consumes.

Are you using the charger that came with your radio equipment? They're often called "wall warts".

What do you use to tell the amount of charge that's still in your batteries?

well take your plane and place it on the ground where you seem to have problems at the same time of day you had problems previously with a fully charged battery and turn on the tx then the rx and see what happens,move the controls around and see if they respond correctly.

It seems to be something like opjose said... Harmonics

When a signal going through the air bounces on something (building, mountain, etc) it may change frequencies. Those frequencies can be so close to your RXs. That it will interfere. And it can only be in some "spots" in the air. At a club I used to fly long time ago, there was a "spot" where we would normally turn from downwind to final where almost ALL aircraft on 72MHz would glitch. It didn't matter if you were going fast or slow, leveled or at a bank, the airplane would glitch rapidly on that spot. When we found out about this, we tested with different AC flying throught and some would jump up, some would loose RPM and turn for a sec, basically glitches.

But there are "harmonics" that can upset the RX...

The funny thing is a radio scan with a frequency checker ( with the extension antenna ) shows nothing!

However the "hits" have been very real.


When a signal going through the air bounces on something (building, mountain, etc) it may change frequencies. Those frequencies can be so close to your RXs. That it will interfere. And it can only be in some "spots" in the air.


oppjose and VFR_RC

The receiver filters out all signals except the ones in the band we are using(72mhz). When 2 radio transmitter signals are present at the radio receiver they can mix and/or combine to form the fundamental 72 mhz.

For instance, you may have two radio transmitter towers close to your feild. If tower 1 is transmitting 410 mhz and tower 2 is transmitting 482 mhz the difference of the 2 frequencies is 72 mhz and your receiver will see it. That is why you may not be seeing an interfering frequency on your scanner-the interfering frequency is formed IN your receiver. The interfering signals usually have to be pretty strong to effect the receiver. This usually occurs in only certain specific areas and weather conditions can play a major role in it's existence.

This phenomenon is called Intermodulation Distortion and is practically impossible to eliminate.

Cecil

Yup, and although the prior poster misunderstood the meaning of the term "harmonics", the overtones caused by other transmititters will also do exactly the same thing in combination.

We've been able to document one such repetitious occurance at our field that will hit planes EXACTLY every 15 minutes.

A frequency checker shows no activity while the planes exhibit "hits" on the particular channel.

Needless to say, that is now a "banned" frequency.