mercula

My Feedback: (1)

Ive got a 9CAP, with PCM
It only stays in failsafe WHILE GETTING INTERFERENCE , Right ?
Then reverts to total control within miliseconds . Right ?
There is nothing to "reset" with any certain stick movements ,Right ?
Ive done a search and seen the many arguments , and this is by no
means an attempt at another one ! Basicly if I hit constant interference
my plane is going in , PPM OR PCM .
Thanks for the info.
NATHAN

wyflyer

My Feedback: (7)

When you get interferance in PPM (also called FM) the airplane glitches and if the interferance lasts long enough the airplane will crash.

In PCM, when the system receives interferance, it goes into hold and almost immediately after that into failsafe. You don't have to do anything to get it out of failsafe. It goes back to normal automatically when the interferance stops. If your airplane hits constant interferance with PCM it has slightly more chance of survival than with PPM, but both are slim to none.

mulligan

This depends on how "failsafe" is used. If "failsafe" is used in the traditional sense, then when interference is encountered, the controls should be set to hard over and kill throttle, which will cause the plane to hit the ground as quickly and as near as possible and with as little energy as possible.

Some use the "failsafe" to hold the last control position, which can be considered a safe failure if you compare this to the possible alternative of interference causing erratic behavior of all controls, which could possibly yield a little more time before impact. This of course depends on the plane's last attitude and control input... very random, and not what I consider "safe."

Finally, some believe, as I once did , that "failsafe" will allow one to put the plane into some sort of gentle, slow turn, while hoping to outlast the interference. This is unlikely- more like impossible- as this depends not only on the plane's last attitude, but also the stability of the plane and the accuracy of the commanded failsafe control throws.


And to answer the original question, yes, the failsafe mode will discontinue as soon as the receiver receives a good signal- you can test this on the ground by simply turning your TX off and then back on.

PCM can mask out some interference better than PPM, so you might not get hit as often, but of course you don't want to rely on this as the norm if you know you have some interference.

Sport_Pilot

Since most interferance is short, I would think that the best would be last position, except for throttle which would close.

smokingcrater

That all depends on personal preference I guess... having it hard over is going to put it into the ground fast. the slowest way to the ground is to kill the throttle and neutralize the controls, with a little up elevator, and then depending on the plane hope it will wallow its way to the ground. (i just hope i'm upright and level should i ever need it!)

IronCross

My preferance is to program the failsafe to send the plane into the ground. Full back on the throttle, down and full right on both sticks... My thinking is I don't fly over people so if the plane heads straight for the gound it should not hurt anything but the plane which I can replace... No telling where it will go if FS is set to hold the last position. I would sure hate to see it go into a crowd of people...

mulligan

I humbly disagree...

"A little up elevator" will cause a very unpredictable crash. If inverted, this will cause a nose dive. If upright, you will stall once or twice and then hit the ground in a random angle dive. If in a bank, it gets even more unpredictable. In any case, I'll bet you my engineering degree that you will hit the ground with a higher speed than if you hard-over the controls, although the speed will have a random vertical and horizontal component.

The reason hard-overs produce the "softest" crash is you go into a spin, which bleeds the most energy from the plane on the way down. Also, you're guaranteed to crash as close to where you lose control, so the plane will not travel far, potentially into a more populated/harzardous area, before ditching.

If you're a nerd like me, you can look at from an energy point of view: At any arbitrary point in flight, the plane will have a certain potential energy (based on altitude) and kinetic energy (based on speed). There's nothing you can do about the potential energy- it will be coverted to kinetic energy as you descend to the ground. Everyone (I hope) agrees that killing throttle is the correct thing to do; this reduces kinetic energy. Well, the only other thing we have control over to minimize speed, and therefore kinetic energy, is drag. The way to create the most drag is to deflect all controls to max. throw (some would suggest opposite throw on aileron and rudder will produce more drag).

If you're hoping that the vertical speed will be less and you will "wallow" in, this is a very thin hope... and then you have to hope that your plane is level- again, thin.

From a safety aspect, most of this is trivial. As IronCross says, the real safe aspect of hard-over controls is to keep the crash close.

JohnMac

Well I have to say that I strongly disagree.
1. "Putting the controls hard over produces a spin". No it doesn't! It appears that you are confusing a spin with a spiral dive. In a spin the aircrafts wing is stalled during a yaw and an autorotation develops. When this is fully developed to the point we may call a flat spin, then in some cases the descent rate may be relatively low, but I would not want my jet to flat spin in!
2.Holding the controls hard over will produce a spiral dive. Given enough altitude, a model with a high lift wing such as a glider for example will often loose the wings (compression failure as a rule) as the model accelerates and exceeds VNE. It sure as hell will not slow down!
3. No one can predict the point at which interference may occur, the models attitude or what it might do next, but we can apply the law of averages with a little intelligence. A fair proportion of models are designed with some degree of stability (not aerodynamic stability, model stability), but not all. If we set our failsafe to hold last position the model is on a predetermined flightpath right at that moment and it could end up anywhere. Any inherent stability the model was designed with will be defeated. If we set of controls to neutral, the model MAY heve time to regain a stable flight regime. It also could end up anywhere, but it provides precious seconds. In these seconds we may avoid the models flightpath, shout a warning, or ideally regain control. There is a significant degree of chance (law of averages) but recovery can, will and has happened. In either of the other 2 scenarios outlined recovery is either not possible (controls hard over), or very unlikely (controls set to hold). I appreciate that many models are inherently unstable, and have little chance of recovery but even here I can site examples.
4.In the UK it has now been ruled that failsafe recievers must be set for the controls to go to neutral and throttle to idle. This was brought in after the death of a boy directly as a result of a PCM receiver being set to hold.
If we want to increase saftey from interference, and since the number 1 cause is other modellers switch on without the peg, a mandotory channel check system would in my opinion be a major step forward.
Regards,

John.

allancito

My Feedback: (2)

Guys I need your help and a comment or two.

First I am using the new FMA 8 channel with auto pilot and in fail safe my models fly level lazy circles until I yell at the mother who switched on his radio without the frequency card in his hand. It absolutely 100% saves planes and there are no more crashes due to interference, fly aways etc. The worst problem I had was student who got his plane out of range and it was last seen flying wings level out to sea. There are 6000 miles between Chile and New Zealand so I am sure it never made dry land.

In your litigious society if crashing is a potential issue then I just cannot do more than recommend the new FMA 8 channel system. YOU WILL NEVER CRASH AGAIN DUE TO RADIO INTERFERENCE OR LOSS OF CONTROL FOR THAT MATTER. If your pride suffers then just set it up so it only works in fail safe.

Anyway heres my problem.

I have a new 9ZA WC2 and I fitted a NBS 2100 NiMh battery pack to it. That should not cause any of the following problems.
Also I use Hobbico PPM, Futaba PCM and lastly FMA 8CP with DSR. The symptoms happen on the lot so it is not a receiver or brand issue.

With the radio and receivers on if I touch the antenna with my hand the servos go ballistic. ALL OF THEM. If I walk around the plane ( I have six flying and they all do it) when I get to the front left the servos start to jitter and when I get closer to the model they go off ballistic again.

If I fly and I do I can see the model get hit with either a rapid rudder flick or an elevator or aileron flutter. The hits are rapid and not constant but if I am near the ground it does nothing for the heart.

Today I had this supposed interference really bad on my FANTASY. Oh by the way this is engine off in all cases and on the ground. So I sat my radio a few meters away from the model and let it do its business. After about a minute it settled down and for next 40 minutes nothing moved. I picked up the radio and walked around the model and it was perfect. The FMA receiver shows how many times the radio was hit with interference and it shows nothing. If I turn on my second radio it registers the hits so I am beginning to think it is in my 9Z

My radio has a synth unit just for information. There is an airport about two miles away with a considerable military presence. ( We get permission from them to fly so no worries) There is a lot of GA traffic and the commercials as well. MY frequency on all my planes is 72.090 (15)

We have a small club and fly with five or six guys on the weekends. They never have problems.

I am at wits end with this problem ands wonder if you can point me in the right direction regarding this.

Heres hoping this leads to some answers.

mulligan

John,

You have too many errors in definition and logic in your post to address in another epic (I say this since you "strongly disagree" ) [sm=punching.gif] .

I'd rather let it be to others to look up the definitions and physics involved.

I am sorry for the loss of the boy's life as mentioned in your post. However, as is typical with reactionary rules, the neutral failsafe requirement misses the mark.

mulligan

Allan,

Are you using a 6V system? If so, test to see if the symptoms are related to the receiver battery being fully charged.

You mentioned turning on a second radio to artificially produce interference. Can this radio be used to control the plane with the 9Z off? Ideally, you could see if the symptoms continue with another transmitter controlling the plane. Alternatively, can you swap out a receiver and check it?

Do you have any other planes you control with your 9Z? If so, any hits on those planes?

allancito

My Feedback: (2)

George.

The same happens on all six planes and yes they are all controlled with the 9Z and the 8U if required and with the same result. I took some time today and hooked up my laptop to the FMA reciever. Sure enough the rudder just sat there and rumbled away with some slight twitching on the elevator and throttle. Wings were off as my little shop has a reputation for wing bashing if I work on them fully assembled. The rudder movement was visible on the display and that makes me think the movement is signal generated and not a crook pot in the servo. Plus it happens on the others so servos are pretty much eliminated.

My power system on my large models is all 6 Volt. One has a NiMh 2000 MaH pack and it twitches and glitches. MY Fantasy has regulated LiPO system and the voltage is really stable according to the data I get in my laptop. There was a voltage fluctuation of around 0.3 of a volt between the model with no servo movement and me fully throwing things from side to side.

However I think I have found something. I am not sure if it is the radio or the receivers but it appears that if I leave everything turned on for few good minutes (10) then everything settles down until in the end the whole rig is really stable. The pack in my radio (9Z) is a 2100 MaH NiMh pack and it tops out at around 11.3 volts fresh off the charger. The 8U has radical RC 1600 MaH NiMh pack and it will go to 11.8 volts fresh of the charger.

Because the FANTASY is regulated with a smartfly regulator and switch it has a reall stable six volts to the servos and reciever. If that is stable then I find it a little hard to understand why letting things warm up would make any difference. However the transmitter loses the top end voltage really quickly and once that has settled to say 10.8 volts or less everything start coming right.

I know one thing for certain and that is this is not an interference problem. It is either the radio, the synthysizer or all of my recievers. I feel comfortable it is not all of my receivers.

Thus the three common denominators have to be Battery voltage in the radio or leakage from the synthesizer or the fact that six volts is too much for the recievers. Or a combination of all.

Can you help me on these items or do you have some other ideas.

I need to get to the bottom of it as it is surely disconcerting to watch your model throw a full epelictic fit and then five minutes later off you go and fly it hoping like hell it has stopped.

Regards

Allan

allancito

My Feedback: (2)

George.

I am off to my little shop to fit an isolator today and a second battery for the reciever.

That will split the feed and isolate the 6V from the reciever.

Will be interesting to see if this tames the beast.

Regards

Allan

mulligan

Regulated 6V is certainly not too much for the receivers. Most will tolerate unregultaed 6V packs (peak of 7.1V), although some will twitch at peak voltage.

I was confused, though, about using the 9Z and 8U. Did you say you are getting the same glitches with both TXs (that would seem to eliminate the TX, unless you are using the same frequency module- that could be an issue)?

Another failure point to isolate would be the TX battery pack. Swap it out and re-test. I've never heard of a TX battery issue causing an erratic signal, but I suppose it's possible.

allancito

My Feedback: (2)

Mulligan,

Well just back in from a morning of frustrations. I installed the isolator and the damned thing changed all my neutral points big time so it took me an hour or two to redo all my linkages. This is my pattern plane and I trim it with all trims at neutral and use no sub trims at all. The reason being with the 9Z I use three conditions and the goddam trims change with each condition and I have not yet worked out how to keep the sub trims the same across all conditions. Radio is six months old and the pilot is 50. There seems to be a generation gap in here somewhere but I am getting it sorted SLOWLY.

OK seperated the systems and it settled down a lot. Both radio and plane had been on charge all night so batteries were tanked right up to the max. There were some very minor glitches but so small and so fast you would likely not feel it or see it in the air. Then I went back to the same power feed ( My regulator switch has two outputs ) for both the reciever and the islolator and it still seems a lot better. During the hour I had it sitting on the bench with radio and plane powered up I had only two serious belts where the rudder and ailerons gave a healthy kick. My reciever said I had two bad packets of data during that hour but FMA say anything less than thirty bad packets is not an issue. In both cases it did not go into fail safe so the glitching to my mind was internal and not from an outside source.

However I found yet another trick. If I walk between my radio and the plane it go crazy, but not every time. If I run my hand over the plane it sets it off but again not all the time.

My cellphone was not in my pocket but it was on but well away. It rang a few times and nothing moved so I am not in the cell phone blaming league.

I am getting to the stage where next rick will be to remove my digital watch and wedding ring. Plus make sure my clothing is not static loaded. No nylon etc.

The problem happens with both radios and they do not share transmitter modules. They are on the same frequency. One is a synth module and other has a crystal.
The problem is definetly worse with fully charged batteries.
There is nothing bad going on with the transmitters turned off. The plane does not buzz or fidget until the radio is turned on.
If I touch the antenna on the radio it sometimes causes the model to glitch and sometimes seriously.
As an instance at the field with everything on if I wave my hand between the radio antenna and the plane it glitches.

If I walk around the plane with the antenna close to the model it sets off always in the same place.

Mate I do not believe in ghosts or fairies for that matter.

I do not have another pack for my 9Z as they use a cartridge but I will invest in one this week. But this was happening before I installed the 2100 MaH pack so that should eliminate the transmitter batteries.

The next best thing for me is to get another frequency and see if there really is some wierd and supernatural explanation for this. It really has me buggered. I am no slow poke with electronics and mechanics as that is my business but this one driving me bloody nuts.

I just cannot explain why the plane throws fits for no known reason, then comes right for the rest of the day.

I do know however that I will get to the bottom of it with help.

Sorry to bore you with this but it is a step by step process.

Regards

Allan

Phil Cole

allancito,

Are you using the FS8 receiver? Despite all its features, it's still a PPM receiver. If you are testing with very strong signals, it would not be unusual to see the effects you observed. When the transmitter is very close to the receiver, the signal can get into the receiver through a number paths other than the antenna. These signals from different paths recombine in the receiver with unpredictable results, sort of like when you get multi-path reception on an FM broadcast receiver.

Try your tests with the transmitter twenty or thirty feet away (antenna retracted) or at a distance representative of the transmitter - receiver separation while flying. The result should be the same as you get with any normal PPM receiver. The FS8 can do things other PPM receivers can't when dealing with bad signals and interference, but it can't do any better than any other PPM receiver when operating normally with a good signal.

allancito

My Feedback: (2)

Phil.

I just had a very good recommendation through a personal response to this thread and I think it is worth sharing.

RTK mentioned he had a similar problem with the 9Z and it was caused by the ATV being too high and the AFR at near max as well. With these two near the limit something was causing the glitches similar to what I am suffering from.

I know my ATV's are high and I have the three conditions set around about 130%. I then use the AFR to set my rates and exponetials. I do not use the dual rate function at all and leave it inhibited.

Will know more this afternoon once I go back to my little dog box and play some more.

A million thanks to everyone so far for the help on this.

I was getting desperate.

Regards

Allan

fritzthecat

My Feedback: (4)

Just for fun install a 4.8 volt battery in your plane and see what happens. Some servos/receivers don't like any voltage higher than 5v. So far it seems to me the servos go crazy until the battery looses it's initial high surface charge and once the voltage drops down a little the system mellows out.

Fritz

Panzlflyer

My Feedback: (15)

Its highly unlikely that its the tranny voltage. I have a 9Z and used to have a 9c use liion in them and when fully charged they will show 12V with no troubles. Like wise with the receiver Futaba says theirs can take way more than 7v. Servos will dance and then settle down with a unregulated 6v system as the battery settles.
You can swamp a system by transmitting to close to the plane.
Like the previous poster said try it a little distance away and see if it does it.

Dave Harmon

Allan....the problem you are having with the trims not carrying over to the conditions is caused by an incorrect transmitter setting.
With all conditions off, go to TRM, then each stick T1>T4 one at a time. Push CMB. When correctly set, the mode will be NOR-C on all trimmable channels except for the throttle channel which should be ATL-C. This is covered in the book under 'trim'.

As far as the other problems you are having, I suggest you remove the RF link by using the DSC cord with fully charged batteries as before.
This will determine if the RF link has anything to do with it.
My personal feeling is that you need to get the voltage in the airplane to 5.1 with a regulator.
I use the JACCIO regulator and a 6v battery with my ZAP and there has never been a hint of a problem.

Regards

Dave

allancito

My Feedback: (2)

Thanks a million everyone who helped me out there.

I think I have the FANTASY nailed and flew it twice today with a lot less servo jitter than before. I have fitted an isolator and have the receiver running of a seperated power supply. The rudder servo is jittering a very tiny bit. It is nothing to do with the radio as I setup my 8UAP and had the same result. It is getting some form of rf that just does not quite seem right.

It also has nothing to do with the radio being close to the model and swamping it. In flight I can see the rudder doing this little fidgeting motion but it is so small you do not feel it but you can see if you do a good close fly by. I will fit a filter to the rudder circuit tomorrow and see if that sorts it out and then if it does I will drop in one of my FUTABA PCM receivers with no filter and see if that cleans things up completely.

I suppose it could be the pot in the servo but I do not have another one the same size (HITEC 5945) to swap out and try. It is pull pull and not highly loaded in any way. The wires are firm but not guitar string tight.

My biggest fear is this is finally leading to the FMA 8Channel Co Pilot receiver being dodgy but then again lets wait and see. I had my hopes set high for this given it is a fully failsafe PPM unit at a very good price.

Will keep you all posted