Xantos

Hi Guys ,
Ilost a Kingcat yesterday due to what I can attribute to unexplained 2.4 issues.
I was using a JR DSM9 radio with the 9ch Rx and 2 extra remotes , the kingcat was rigged with 2 x Powerbox 2800mA batts for Rx , 4000mA Powerbox batt for ECU , Powerbox evolution , Powerbox smokepump , Jetcat Afterburner ring and a Jetcat 160.
Aircraft had 25 flights on it without incident data logger had shown Rx and receiver location to be OK - No fades or holds.

Here was an aircraft that was perfectly setup , redundant systems etc and a troublefree history flying at theand same airfield,but on Sunday , on the first flight after takeoff and into the 2nd circuit the Gear dropped and turbine shutdown and no control was restored until impact.
Everything was detroyed !
This is the 2nd time a similar thing has happened to me with a 2.4 system, the first time was with a large Gas heli which went into Failsafe but regained control after a few scary seconds , never flown the heli after that.Again the set up was a fully redundant power system, additional remote extensions and over 10 incident free flights to prove the system
The point is- the 2.4 system seems to have too many quirks and bugs most of which are encountered during setup i.e while binding or after binding some systems will cycle the gear on powering up or a bound system will require to be recycled or have to go thru the binding process again because lights on one remote will keep flashing etc .
Or even worse you could just randomly get hit by the system going into failsafe for no assignable reason whatsoever.

I know there was ahuge controversy about Ali's Hunter crash on RCU sometime agoand the thread ran into many many pages with various people pointing out to the cause of the crash and advocating redundant power supply systems etc.
Itdefinitely beyond doubt that the weakest link today appears to be in addition to batteries , also our preferredprimary control systems

My post is not JRor Spektrum specific , I know Futabaalso has its own issuesin high operating temperatures etc but I have nofirst hand experience with Futaba
I also know that there are many people out there that have many successful flightswith 2.4 systems
I myselfhave logged probably more than200 flights since the spektrumconversion modules came out
IMHO I think if we look at pure percentages,the older 35, 40 , 72mHZ systems are relatively troublefree whencompared to the2.4gHZ technology out there.
The percentage failure rate on the 2.4gHZ seems to be unacceptably high !
In my 20yrs experience with the older FM/PCMsystems I've NEVER had a failure that could not be explained
Interestingly the Europeans do not seem to have switched over wholeheartedly to the 2.4gHZ tech.

My observation is from 3 consecutive years that I have visited the JETPOWER show in Germany - most of the pilots (90%) seemed to prefer the 35 or 40mHZ system - I wonder if there is a reason for this ?
My question for all of us to consider is :

[*]Is the 2.4 technology really ready for the hobby ?[*]Or are we enthusiasts guinea pigs for a evolving technology where the manufacturers are doing their R&D at our cost ?[/list]I am definitely pulling out all my old but reliable 35mHZ receivers and possibly go with a twin Rx RRS system - No more 2.4 for me !

Xantos

bigplumbs

Firstly I am very sad for you loss however I would make the following points:

1) As you will see I am from the UK and in my experience 2.4 gig is certainly taking over from 35 Meg over here. My local hobby shop doesn't seem to sell a 35 meg radio any more. At jet meets I would also say that 80 % plus of the pilots are using 2.4. I would also say that generally spektrum is more popular than futaba or any other systems.

2) I was one of the first people in the UK to buy and use a Spektrum DX7 and despite the initial problems with the now known software fault on the AR6100 receivers I have had well in excess of 500 flights on planes ranging from small parkflys to turbines and have not had a single worrying issue. I have had the odd bind that fails initially but this is easily corrected by switching off and switching on. I have also had what I call the spektrum shimmy where the retracts ping up and down on my DSX9 at switch on. Others have had this also but it is generally sorted by a rebind with the retract switch in the down position.

3) When I started in Jets I only did this because of 2.4 because I had read so many reports on these forums about lockouts and failsafes etc on 35 meg. I am convinced that 2.4 is far safer and better than 35 meg for many reasons.

4) I think part of the problem is that we expect 100 % reliability. this wasnever the case on 35 meg and will notbe the case on 2.4 but I am certain that 2.4 is far better.

5) For me knowing that you cant switch on the wrong model or some joker in the pits cant switch on and shoot you down while you are flying is worth a lot. Also to not see my smaller electrics glitching about the sky is also very valuable.

6) I also suscribe to the basic principal of keep it simple. I build and fit out my jets in the same way as all my other planes (and I have 87 in total). Which is basically servo's switch, Receiver and battery. I have never used power boxes, regulators or other fancy electronics. In my view that is all just more to go wrong.

Finally at our field we have had a few people who think that they have had problems with 2.4 and have crashed several models. After a while having put the crashed gear into other planes they have realised that it was somthing simple to do with the rest of the gear. In one case it was as simple as the thread on a push rob being poor and pulling backwards and forwards in the clevis.

So my simple answer is that yes 2.4 is for our hobby now but I fully understand your concerns having lost such a nice and expensive plane

Regards

Dennis

Xantos

Hi Bigplumbs,

From your post it appears that you've had similar experiences with the quirks of the 2.4 tech , which is exactly what bothers me about the technology.

How is it acceptable to us that the odd bind can fail initially on swiching on ? What are the chances that this cant happen in the air ?

Ive had a situation in one of my jets  again many flights old where I took off with a perfect bind and landed with LEDs on 3 receivers blinking LED on only one external receiver remained solid  .

Yet on the next flight receiver location unchanged, all LEDs were solid and  datalogger showed good values  - I accepted it then as a 2.4 quirk !

This is exactly what bothers me - there is NEVER any clue why and what is happening

Considering the damage a jet can do how is it acceptable that  we use control systems that can be described as a "Best of Luck" thing -

 While it works its great ! But when it fails we dont know why  ..... ?

Xantos

bigplumbs

I have to see I dont have a data logger and dont tend to check if the lights are blinking on landing. I work in the principal that if all went well on the flight and this has happened many times all is well. I ahve never experienced an issue of loss of bind after the system has bound.

I am also of the view that on those times the system doesnt bind it will actually bind if you leave it long enough. I think however we just get inpatient.

The issues I had were in my opinion very small indeed and have never caused problems.

If you have the quick connect software in your receivers the blinking will be showing some sort of loss of signal but because the reconnect is so quick you will not have noticed it. Not a problem to me if the plane carried on flying and you did not notice it in the air.

One of my friends is constantly wanting to plug his data logger into my receivers when I land after flights that were fine and I never let him. I dont see the point all it will do id potentially worry me as quite frankly I wouldn't understand the numbers anyway.

If it aint broke dont fix it I say.

I would agree that because I have had only good experiences of 2.4 I am confident with it. I fully understand your loss of confidence however because of your sad loss.

I assume you have had the rest of your gear checked out or even the module itsself.

Regards

Dennis

sweetpea01

My Feedback: (10)

I'll try to answer both of these Posts



First if your lights are blinking you did not lose signal, you lost power. I'm betting that your RX and one of the satellites came in the same package and thus have the "NEW" fast reconnect software. The one that wasn't blinking did not have the fast connect software. Anytime you have blinking lights it tells you that your RX dipped below the low voltage threshold. This means you need to check for binding or beef up your power supply to the RX. JR/Spektrum will upgrade the one non blinking RX to the new software for free. Just send it in.

Not a Quirk......its working as it is designed.


While I understand your desire to not use the logger, it is very useful. The values are simple.

First value is the voltage currently going to the RX
Second/Third numbers are the 2 main Ant on the main RX. Any number here is a fade
Next number is a satellite and again fades
Next number is another satellite and again fades
Fade is the when all 3 RX's fade at the same time
Hold is when you have 50 of all 3 RX's fading in a row


So simply things to do.

1. Keep individual RX's below 50
2. Keep the Fade below 50 ( for example: If the value was 25 it means that 25 times all RX's faded at the same time. It does not mean that they did it 25 times in a row. By keeping that number below 50 you pretty much guarantee that you will never have a hold because it takes 50 in a row to cause a hold, so if you never reach 50 your golden. If you did happen to reach 50 then you are still beating the odds that all of them happened at the same time).


Now to explain Fades. Fade is similar to your computer. When you are on the internet and download a picture the computer sends and receives packets of data. It then reassembles them on the computer mainframe to show the picture. Its pretty much the same thing with your 2.4 radios. They send packets of info to the RX. When you miss a few it doesn't really hurt as the update rate is quite fast. You can't think of your 2.4 system in simple terms. When you hit left it doesn't just send a left command, it most likely sends about 30 small commands that equal left. This is why losing just a few is not a big deal.



As for checking with a logger after every flight? I don't do that but I do typically check at least once per day and always at a new field. I have found that in my Giant Scale gas planes that some fields I had to move the orientation of an antenna to get the low numbers. Then I get back home and I had to move it back to where it was originally to get low numbers. I for one think its a great device. For me its like checking the voltage in your batteries. You don't have to do it, but its good piece of mind

Moerig

Xantos,
No point in getting any answer here.
Facts are simple:
The 2.4 Technology is not yet good enough from a software and RF viewpoint (FULL STOP)
The Power supplies employed in the RX is nowwhere near good enough to withstand transients in voltage (FULL STOP)
Recovery from a brownout is not good enough(FULL STOP)
Adding redundancy with powerboxes increases the failure mode since there is no regulator on earth that can emulate the low internal resistance and transient response of a good quality Ni MH battery.
You will see a flood of people who disagree. None of them have lost a Jet yet. Statistically a 10% failure rate will give you 90% which has no problems. 10% is BAD and poor odds.
Save this post. In a few years the marketing material for this material will claim they have found and researched at great cost (yours in reality) the exact problems which somehow was not obvious to them now.
Let those who disagree now reassure you that this will never happen because the systems JR and others have given us have been 100% all the time.
Buyers denial eventually turns into buyers remorse,,,

David Gladwin

Sorry about your loss but no electronics are 100% failsafe. Qantas recently had a very nasty incident (serious injuries were incurred) when a flight control computer component malfunctioned on an A330, control being lost for a short time, and Singapore Airlines had a similar incident on a 777 fitted with the sametype of unit.

I have had 100 % success to date (20 months with not a single frame loss) with Spektrum in 3 jets but have just been testing the new Weatronics Micro 12 channel 2.4 This is a bi-directional unit which gives a constant confirmation of the link by a green led on the Tx unit , records details of the link on an SD card for later perusal on your computer and can trigger warnings, red led or an aural warning if using the earpiece, of RSSI, battery voltage and receiver temperature. In addition, due to the patch antenna it has exceptional range.

First impressions of this unit (11 jet flights with perfect operation) are highly favourable and continuous confirmation of a perfect RF link thanks to the bidirectional operation is really excellent. All these Micro receivers, 8 , 10 or 12 channels, have inputs for two batteries virtualy eliminating the chance of power failure, too.

The larger weatronics DR will have all of the facilities of their previous unit plus some and uses the same 2.4 Rf of the Micro system. I hope to have one of these for evaluation very soon.

That said 35/ 36/72 mhz is far from dead, I still fly my Hawks on that band and Nick Smith was flying his superb KingCat at Wroughton yesterday on 35 with continued complete success.

Regards,
David Glladwin

Silent Lamb

Hi Xantos - sorry about your loss!

This is going to be interesting to watch!Probably end up in a JR/Futaba showdown which is not what you want. Your question was "2.4Ghz - is it reall ready for Hobby use?"

The answer is yes. I was one of the sceptic's about 2.4 because it is really an unregulated environment and a "free for all". Since its inception here, I have only seen 2 incidents of radio loss on 2.4, they were neither JR or Futababut anaftermarket add-on. These guys had no problem at their club but only at one location. So out of around more than 3000 flights, 2 failures 99.93% reliability on 2.4 GHz. If we stick to JR/Futaba, I have not seen one in 2 years - 100%. I am not referring to park flyers but on jets and large scale(where my main interest lies).

Reliability of radio systems also depend on the right installation procedures. Extensive ground tests with motor/turbine running are essential.

If I were to buy another radio now, I would go 2.4GHz. I still fly my JR 53 mHz stuff which has been trouble free for 16 years now. I am slowly converting my jets to 2.4GHz now because 53 is no longer freely available now. Sad to see my favorite JRPCM 10X lying in the cupboard now. Anyway, need to try and understand Futaba un-logic now!

Xantos

Thanks for the many replies.
David Im sorry ,I know nothing about the weatronics 2.4system so cant comment.
Silent Lamb I agree with your views BUT like I've said in my earlier post "right Installation" and setup were not the issues with the airplane that crashed
My only reason for posting this was to see if others were having similar issues with 2.4 tech.
I probably dont fly as much as some other people, I am at best a serious weekend flyer who logs 5-8 flts a week , we fly all year as we dont have extremes of weather and
based on my experience a 1% failure rateis simply not acceptable ,
It raisesa very serious Safety issue which unfortunately will not go away when there is an incident.
Even today , sometimes when I power up myearly JR 9X II which was converted to 2.4 (Spektrum Conversion) ,It still is erratic- sometimes will bind immediately at other times will have to beshut down and powered up again BUT I have 168 flts on my Bobcat with this radio.
Im not saying 2.4 does not work - What Im saying is WHENit does not work we have no clue why
What Im saying is that due to the erratic intermittant nature/behaviour of the 2.4 system with a failure rate of1% is it safe enough for JETS ?

Every country USA,UK Europe etc have their own laws/rules for evaluating the airworthiness of Jets and Largeaircraft and I think not enough consideration is given to the control system in use.
Manufacturers cannot simply be allowed to get away with clever marketing and be allowed to commercially release aunproven product and continue to develop and refine the product at the cost of the customer - It is unfair !
This is exactly what Spektrum has done.
Was there ever a mention of"Brownouts" when the first Spektrum conversion kits were released ?
So also,fast rebooting receivers were unheard of !
Clearly the technology was introduced prematurely and has been refined at the cost of the customer and even today is still evolving.
Xantos

GrayUK

I would not go make to 35meg now, very happy with the solid RF link I have experienced for 2 years.

Paul

MaJ. Woody

My Feedback: (28)

Hi Xantos.
I am very sorry for your loss. As you know I lost two new jets back to back on the same day. If you have not been in that awful, sickening, helpless position of no control and then feel the pain of having lost your prized possession I think its really hard to relate top how you are feeling. I know how you feel my friend. I was very hesitant to go the 2.4 route but then did. I felt like it was the best decision I ever made. Crisp control, no worries about some careless person switching on their radio and taking me out. I logged about 300 flights without incident. Over 200 of then in 4 different turbine jets. Then the unthinkable happened. That fateful day that will ever change how I feel when flying. I will never know what happened but I know it was not structural or mechanical. It was something with the radio equipment. I cant really describe how hard it was to get back on that horse (with new equipment) and have fun flying again. I have logged 20 turbine flights since the crashes (the weather has prohibited any more than that) and it was only on the last two that I felt like I was having fun again. It has changed my flying style a bit.One of myfavorite maneuvers has always been the low high speed pass down the runway. I just cant do that with any confidence anymore. I have seen what can happen and that will always be in the back of my mind somewhere. Bottom line is that I had 100% faith in the equipment and felt it was unfaultable. Now I know better. I love this hobby more than words can describe so I have chosen to stick with it. Hopefully I wont ever experience anything like this again for a long time. In 28 years of flying I have crashed my share of planes. But I can honestly say that I have only experienced any type of radio failure, be it glitches or full lockout less than a half a dozen times. Pretty good reliability given the thousands of flights that represents. I am not qualified to make any statements about how reliable 2.4 is or whether it is the right time for the hobby but I think it is in theory the best thing we ever had. I know that nothing is bullet proof and that every time we fly we are taking a chance but I will continue to enjoy this hobby that has given me such joy, education, skills and cherished friendships.

AndyAndrews

Man, so sorry to hear about these loses. I feel for you guys whole heartedly.

Woody, have you decided to stay with 2.4? I think that all of us are so excited about the ability to no longer have to worry about frequency control that we have all kind of ignored these incidents hoping they won't happen to us. Even though I personally have never had any of these issues, will I be the next one who makes a post like this?

I heard that the European 2.4 systems are different than ours? Is this true? More still needs to be known about how JR handles power loads on 2.4. It seems that the systems are extremely sensistive to power and how clean the supply is.

This is frustrating to hear.. again...

Andy

Hammbone

My Feedback: (309)

Very sorry for your losses guys.

I think a lot of the losses that have occurred with JR / Spektrum have been due to poor current flow, low voltage issues.

I still see a lot of guys using standard plugs to supply the power into their rx's. These plugs are only rated at 3 amps. That's just not enough current flow guys. You are going to have limited current flow and voltage drops when using standard plugs. Why risk your jet?

I still see inline switches being used. A lot of these inline switches are only rated at about 5 amps.
I also see batteries being used that are not up to the task, and undersized wiring, etc.

You can't suck an orange through a straw.

One of the best new products that have come to market recently is the Powersafe rx's that JR has (the R1222 rx, the R922rx, the AR9100 rx).
These rx's are great. They provide 2 HD inputs for current into the rx, and they come with a failsafe switch that is not an inline switch and does not limit current flow in any way. I highly recommend these rx's.

Other options are Power Expanders, PowerBoxes, or similar components that provide for proper current flow.
You should chech the manufacturer ratings of each and every component you plan to install in your plane and make sure it is up to the task. All it takes is one weak component to cause low voltage or limited current flow.

As mentioned above, these 2.4Ghz rx's are extremely sensitive to low voltage. While you could get away with a set up that provided limited current flow and voltage drops on other systems (72Mhz, 35Mhz, etc.), you can not do that on the 2.4Ghz systems.

Jim

Duncan

Xantos,

sorry that you have lost your model, I had the issue with the retracts doing their own thing when switching on as you stated

I found the reason was operator error (ie Me ). If the power is switched off with the retracts up (i did this to load the model in my car) the clever spekky system remembers this and it becomes the position for every power up. To undo this, power on, cycle your gear a couple of times, finishing in the down position and then power off.

Yes it is a bit of a quirk, but like everything new, once your used to it, it's a non event.

Duncan

MaJ. Woody

My Feedback: (28)

Yep. I stayed with 2.4.

hpais

Xantos,

Very sorry to hear of your loss.

Major Woody,

I am a sincere admirer of your work and again, I'm still sad when I remember what hapened to you. Glad to hear you're sticking with it!




In our club, three weeks ago, a member lost a brand-new CARFTucano on its maiden flight. The loss of the aircraft was very similar do the description of the creator of this thread - XANTOS.

In the case of the Tucano, the loss was traced to the voltage regulator! It was fed by dual LiPos, which survived the accident by the way, but the voltage regulator died... - we call it "Infant Mortality". Electronics tend to fail in a BATHTUB curve, that is, they either fail early in life, in the first 10-20 hours, or very late in life - after 10,000 cycles, or after a very large number of power cycles.

When you say you have redundant batteries, indeed you strengthened one link of the chain. But you still have a weak link in the form of a single regulator. It doesn't matter if it cost 700 Euros, it's still a single component.

IMHO, you have two options as far as powering the electronics go:

- Either you stick to the true and tried 2 NiCd's, which don't fail, and don't have a "fail open" failure mode (unlike NiMH's which fail open circuit - 0V!...)

OR

- You use two regulators (like the Hercules, Align) - $30-$90 5V or 6Vregulators - each one with its own battery and connected to a separate battery port on the receiver

As for the receiver, you should do a stress test like recommended on another thread (forgot which) - you LOADthe flying surfaces and exercise the servos and do it for what's the typical duration of a flight - 6-10 minutes. Any stillborns will reveal themselves, either the receiver, regulator and servos.
Obviously you're not testing to failure, that is, trying to destroy your plane or your electronics. But still you need a realistic load on each flying surface that represents what you expect to see in flight.

My conclusion is the same as Major Woody and others - the problem is not the 2.4GHz. That's a part of our hobby's infrastructure that has improved, gotten way better!
But a chain is only as strong as its weakest link - and a single regulator is a weak link, regardless of its cost.

My 2 cents,

Hermann

SinCityJets

Uhhh, Hermann,

You forgot to mention the third (and best) choice for batteries....A123's.  Ditch the regualtors and ditch the 40 year old technology.

Chad

jmohn

Sorry about your loss! I had four crashes on spectrum using the old software. All four were a result of "brown outs" or low voltage. I ened up testing a dozen receivers and it took them 2 to 13 seconds to re-establish the link to the transmitter. After the last crash I switched to a JR 9303 using the new Spectrum (JR) 921 receivers with the "qick connect" software. I have over 100 hours using this sytems on multiple planes and haven't had one issues. I use voltage regulators on all my planes too. The quick connect feature remains locked on the last two frequencies if it gets a power disruption and does not "re-boot" this prevents loosing the plane.

Jeff

Knock

My Feedback: (2)

Sorry you lost your pride and joy , been there . Of course my response to this sort of thing is are my installs adequet . Are a lot of guys successful using the A123s directly into the faast reciever without a regulator ?

Woketman

My Feedback: (6)

I too am using A123's, but straight into the RX worries me due to the high voltage.  I am using the Electrodynamics diode based isolation circuit that drops the voltage about 0.8 volts.

Makes me feel better anyway!

DougV

I'm using A123's 2300on Futaba FASST R6014FS, R608FS/HS (6 in total) unregulated for about 6 months now.

Doug.

NUNU

Moerig I agree with you...sometimes the devil I know is better than the one i dont...i almost lost my superhornet to the first spektrum units..i eventually lost anotheer aircraft to it a pusher falcon 120..i have observed as time rolls on how a certain brand keeps coming out with newer versions and more antenna units on its receiver yet the original sales pitch is to lend the idea the system is bullet proof..its been a great advertising campaign as it feed in to the fear of getting shot down and it has been effective in that when ever a plane goes down on 2.4 everyone will crucify the pilot for "bad installation" or maybe it was a bad gimbal or something of the sort...fact jets cost...fact 2.4 is in its infancy 35mhz and 72 while not perfect we at least have much data as to why something can go wrong

lrb75

My Feedback: (12)

One thing that the 2.4 equipment is not immune to is static feedback. My T-rex 250 had a violent tail twitch and a rythmic pulse in the pitch control. All caused by static buildup in the boom. It would build up and discharge back through the gyro or the tail servo after building up for about 30 seconds.Not exactly the same environment as a jet but still possible. So some of these crashes and lockouts and unexplained issues may be static related. Lots of static build up with fast moving fuel through the lines. Maybe even just the air moving through the fuse, but shouldn't be a problem in humid areas.

Jerry K

My Feedback: (1)

In my opion you were short on rx battery !

LIon batterys cannot supply a large amount of current draw. That is the reason they arerun in 2S2P configuration totaling 5200Mah.{the most popular config} The 5200 X2 In redundant form is not needed for capicity BUT is needed to prevent voltage sag in hi amperage conditions.The Kingcat is loaded with a bunch of digital servos and if you were running digitals on the flaps compounds the problem. Digital servos on the flaps in the deployed position if they are not set up properly can draw 3-4 amps by themself.When the flaps are deployed the servo arm and the pushrod should be in a straight line or almost. You do not want theservo motor holding the flight load. A servo that hangs up can draw between 1-2 amps by itself. The way LION batterys are tested is to load the battery with a 1 amp load which will take a freshly charged battery from 8.4 volts down to 7.6 VDC. In my opion again your plane should have had at min. 2X 2S2P 5200 OR another battery chemistry such as A123 or Nicad. NiMi has the same problems as LiON and more problems will surface as Nicad is phased out if you do not move to the newed chemistry.

Jerry

NUNU

see what i mean...its gotta be the pilots fault..bad gimbal..battery ect...one day tho we will have the necessary info to make 2.4 more reliable...we are not there yet tho..trust that