luv2flyrc

My Feedback: (6)

Surprised no one has asked but, is it possible that you simply stalled the aircraft? I have seen more radio hits, crashes and "I don't have it's" in my day that were aerodynamic stalls than I can count. FAR more than failed equipment.

Last summer I watched a big Corsair launch, immediately break left and pile into the ground. The pilot explained to me that his ailerons "reversed" just after launch as he was putting in right stick but, the plane was going left. At the crash site the the ailerons miraculously went the right way. He reasoned that it must have been an electronic glitch in his JR radio that reversed them when he took off and the scarey part is , he truely believed this.

I suggested that he stalled the aircraft on take off as his take off speed was too slow and pitch angle too steep. 'Impossible" he touted, "he's flown the aircraft many times before".

Interestingly, a video shot by a spectator later showed the ailerons full right in the direction of his stick movement but, because the plane was stalled it banked left.

Mike

rmh

It has been over twenty years since I saw a crash which was caused by the receiver not being able to do its job- due to the fault lying in the rx.
Seen:
lockouts -due to conflicting frequencies - quite a few of them
Loss of power to the rx- a number of them
reversed controls - ongoing
The chance that a rx simply quits -all on it's own exists
The numerical chance of this happening is teensy weensy
I consistantly see tiny Bind n Fly models with the integrated 6400type rx, flown to extreme distances -with no problems (extreme being out over 500ft)

Almost all crashes are user induced - lousy setups whatever - but NOT due to a rx simply stopping from an internal fault.

dirtybird

My Feedback: (5)

Last fall I had a little Stearman put out by Efight. A very pretty little airplane but I put a little too much power in it and it flew a bit hot.
I made a left turn in front of me and it went straight in a full power while I was holding full up. I could have sworn the radio quit.
I finally realized there was a substantial wind and when I turned down wind, the wind got under the tail and there was no way I was going to pull it out.
It sure seemed like radio failure.

chuckk2

So far I've had two receivers that were defective, due to poor soldering and component mounting. I believe both were due to strain caused by a shrink rap outer cover. The cover stressed marginal solder joints. One was a crystal lead to circuit board (72Mhz receiver), and the other was a solder dot on the underside of an IC(2.4G receiver). Both receivers were made and sold by a china company under a fairly well known name.
Neither made it to actual flight status, as they failed under initial functional testing prior to actual flight.

The unexplained bit is closer to what I experienced with a couple of models during initial flight.  The cure was to make sure that the receiver power source had the ability to provide peak current and appropriate voltage when servos were fully loaded, and to make sure that servos would not "stall", due to travel stops in the servos or control surface deflection limits.

A servo exerciser and a pulse width readout, along with a receiver/servo current voltage meter can be very useful in avoiding "unexplained" control loss.  For anything over about four digital servos, a battery or BEC should be able to supply over 2A without voltage sag to at or below 4 volts or so.
Testing prior to install of a commonly available name brand electric retract set showed problems that were not anticipated, such as high peak current demand at the start of gear travel. This caused the LED on a 2.4 Ghz receiver to blink with four cell AA receiver batteries. (NMIH, NICA, PB ).  A relatively new, fully charged 2700mah NMIH pack was marginal, due to momentary voltage drop under peak load.
A 5v 2A BEC integrated into a 60A ESC was also found to be marginal. BEC's 3A or 6A with 5 to 6v (adjustable) output worked.
  

eddieC

My Feedback: (2)

If the battery was marginal, how did adding a BEC help? Another cell or going with higher voltage (7.4 + Li-xx or LiFe) with a regulator would be a fix, I would think.

rmh

The BEC's on various ESC's are demonstrably different -under load
very much so- some of em won't handle much of a peak- the linear ones on small ESC heat and fade fairly easiy
IF you ar using extras (retracts forexample)as noted which have high peaks on starting- best bet is a GOO discrete rx battery setup for the rx
I use a A123 pack where possible I also have a ALIGN 2 lipo BEC setup which is quite good under load and has two output voltages which can be used
Peak power spikes are very hard to detect unless you know how-and they can cause problems

eddieC

My Feedback: (2)

Not sure you answered my question there. You use 2 batteries? What exactly was the fix?

Capt Cash

My Feedback: (1)

Yes, receivers rarely ever fail, but excessvive heat will definitely shut them down. I have an experienced friend flying large gassers who had his rxlock out just after starting his plane and taxiing out priorto takeoff. The plane had been sitting in the sunbetween flights in theTexas summer heat. Luckily it was a good outcome.

While most of us always make an effort to put our planes in the shade, sometimes it's just not possible depending on the facilities available. I usually keep a large white towel handy to help out.Buton days like today I just"throw in the towel" and forget about it. It's 108F nowin Dallaswith no relief coming anytimesoon.

An informativelink on the heat issue: This guys receiver locked out around 125F in a similar scenario.
pakratt.weebly.com/b_9-03-11-futaba-r608fs-heat.html

chuckk2

The batteries plus wiring to the receiver or servo tester just didn't provide enough voltage at peak current draw. Also, if you look at the attached Sanyo A size data sheet, it's kind of obvious what happens when there is a high peak current draw. (Even though the charts show continuous current draw, you can assume that a peak draw will cause the output voltage to drop in a similar fashion.)
A BEC rated at a continuous current, will (supposedly) put out at least that current at the rated voltage. If a BEC rated at 2A was used only to power the electric retracts I previously mentioned, and everything else was powered separately, that would likely work. A five cell pack obviously can improve things, as long as it's cells can provide enough voltage under peak load to get things done. Actually the electric retracts work at rated minimum voltage, as long as the peak current draw doesn't cause the battery voltage to drop much below 4.8V.
Measuring how far the voltage drops under a short term peak load is difficult, unless you happen to have a decent oscilloscope. (I don't!) The receiver/servo voltage current meters aren't fast enough to show the peak current draw or the momentary drop in voltage accurately. What they did show was a momentary current reading of about 1.5A and a voltage dip. Both readings are much less than the actual readings, since a receiver that works well with less than 4V showed a momentary "glitch" by blinking an LEDthat is normally on solid when things are working properly. The electric gear has a tendency to start initial transit, and then stop when the voltage or current available is not enough. What seems to happen is that the gear starts to operate, and then stalls at a high current point, the current/voltage protection kicks in and that's the end of gear travel, at least until the gear signal is cycled.

dirtybird

My Feedback: (5)

Solid state circuits manufactured for industrial use(not MIL Spec) do not have a high tolerance for high temperature. Its wise to keep the receiver cool.

AndyKunz

Yeah, glad it wasn't me! The other instructor has a 3-airplane lead over me

But here I am in the shop, assembling the replacement.

Andy

psb667

At first glance (of the thread) I would say your flap or elevator control failed (physically something broke.) Just my opine

bipeflr

My Feedback: (8)

I am not a radio expert however,I know from experience that a bad switch,loose extension,or any intermediate connection can cause the best 2.4 to fail. Jim

dirtybird

My Feedback: (5)

It doesn't take an expert of any kind to figure that out. Just keep in mind its not the 2.4 systems fault.

Aerocal

Im pretty sure if we were talking about Spektrum system it would be ALL the systems fault.

Im also pretty sure since there is a cheap BEC involved that theres a 99.9 and some percent chance that "failure to supply adequate power" is the root cause.Very simple explanation
with no Plug and Pray solution.

Scota4570

I posted earlier that I think it may have been a programming error. Here is a pic of it. It was nice. Covered in dacron and dope. It flew great, very soild and straight. It went exactly where I pointed it and stayed there. Like it was on rails.

nmav8r

Sounds like you may still have been in range check mode

Scota4570

It was my first crash in several years. I guess I was due.

Rodney

Do not fall into the trap believing that a faulty ignition module can not adversely effect a 2.4GHz unit. It can and was definitely proven to be the cause with one of our flyers. Now, this is not likely but, IT CAN BE A PROBLEM. A spark, if enough energy behind it, will radiate in the gigahertz area as well as the lower frequencies but usually at less power density. If this power is high enough it can swamp out the front end of the receiver and cause loss of control.

dirtybird

My Feedback: (5)

The resistance in the wires suppress the higher frequencies the same way a resistor plug suppresses the lower frequencies.
In your proven cause I suspect the power was sufficient to couple directly to the servo pulse wire.
I have a function generator that I can drive the spark system at its limits. There is no way I can get it to interfere with the receiver with the unshielded spark plug sitting on the top of the receiver. I can get it to interfere with the servo if I get the plug next to the servo wires.