sass25479

My Feedback: (9)

In one of these post somewhere I read about hooking two recievers as a redundant system with a fuse in between them. I've searched and have not been able to find it again. Stupid me should have printed it then!

I'm very interested in the different opinions on this topic.

Thanks

sillyness

My Feedback: (25)

I use it. I use the male end of 2 servo extensions, the signal wire removed. I solder the black (or brown) wires together, and I splice an automotive mini fuse holder (radioshack) in the middle of the red wires. I insert a 5-7.5 Amp fuse and I plug the male ends into an empty socket on each RX. Pretty easy. Works great.

One caution though... if you use LiIons with good regs, they NEED to be set to within .01V of each other or you will drain one battery before the other. Mine are set at .01V or less (Fromeco regs) and I get very even draw on each battery.

JettPilot

My Feedback: (6)

Using dual receivers is a great idea, but hooking them together is a bad idea and just asking for fialures of one or both systems. Use two receivers,two switches, two batteries, one for all the servos on the left side of the plane, and the other for the right side of the plane. Do not hook them together in any way !!! That way no one failure will cause a crash, you will always have control over one aileron and elevator.

Why would anyone go to the trouble of installing two seperate receivers and batteries then hook them together, thats just nutz [sm=bananahead.gif]

JettPilot

sillyness

My Feedback: (25)

Well, the reason is that if you run two seperate RXs with Seperate Batteries and Seperate Switches, you basically double the chance of a failure. The jumper minimizes it.

There's an article in the new 3D Flyer (I think by John Gezellis [sp?]) about the jumper setup.

JettPilot

My Feedback: (6)

That reasoning is FLAWED. Yes, you double the chances of failure, but you can land the airplane if either does fail. Hooking them together just increases the chance that a failure will take BOTH of them out, which would result in a crash.

So you choose between to things. A fialure that will result in you landing and fixing the problem, or a fialure that results in a crash. If something goes wrong you need to know right away, you dont want some jumper hiding the problem until both systems quit.

Why do you think airliners have two sperate engines, seperate fuel systems, etc. etc. Everything is SEPERATED so that no one failure will result in a problem that causes a crash.

Whoever wrote that article you are referring to is very misguided....

famousdave

My Feedback: (61)

It is easily demonstrated with math that 2 batteries, two switches and two regs into one receiver has a higher MTBF than ANY dual receiver set up....
That said, in theory one can still fly 1/2 an airplane although I have never seen it be done.....

DP

rc bugman

My Feedback: (30)

DP,

With the many hrs of flying with my research planes which are all set up with dual rxs, dual batt ect, I have had a number of opportunities to fly and land airplanes which one side had died. Piece of cake!!! The controls are just very soft.

If you want some excitement, take one of your fun fly planes like that ultrastick light 120 you have and install dual rxs and batts. However, install the rxs with 2 different frequencies. Hand a tx for one frequency to a friend. Take off the airplane on 1/2 of the controls and fly 3-5 mistakes high. Have your friend deflect the controls on his side and let you practice saving the airplane with 1/2 the airplane. It is a blast and good training. As long as your friend doesn't fully deflect the surfaces he controls, you can recover and save the airplane.

This exercise will make you a believer in dual rxs and the ability to save an airplane with only 50% control.

Cheers Elson

sillyness

My Feedback: (25)

Please provide some evidence (a mode of failure) that explains how connecting the power buses of 2 RXs can result in system failure. If you don't know what's inside a RX, the + and - channels are simply strips of metal... there is no signal or other information on these buses. They are not modulated in any way. I'm very willing to listen, I just need some concrete proof, not capitalized ranting.

Also, please do some research into the identity of the writer of the article. You may start looking in places like the video archives on Flying Cirkus in the sections on the Tuson Aerobatic Shootout, etc... I think you will find that he is intelligent and very successful in the hobby.

famousdave

My Feedback: (61)

Thanks Elson... I believe you.. I know you have probably simulated just about every scenario known to man.. and then some.. I guess without practice I am no better off with one RX vs. two.. and that's why I only use one RX. On the other hand if I could practice recovery that may make all the difference in the world...

Thanks for the different perspective...

DP

sillyness

My Feedback: (25)

That's cool man... I gotta try that! Someone needs to come up with a plane for AFPDeluxe that can do this!

JettPilot

My Feedback: (6)

Just because I told that you are wrong in strong and no uncertain terms does not make it ranting. I gave you good and correct information no matter how you may want to label it.

This issue has nothing to do with the data in the recievers. The vast majority of radio failures are caused by batteries and switches. Here are your likely failures and results with power systems hooked together... A shorted battery, switch, or power lead will short BOTH sides and cause a total failure if you hook the two sides together, you would have no control of the airplane. A bad battery that goes dead will be hidden, until BOTH your radios quit when the remaining battery quickly runs down and dies. An intermittent switch could cause so much noise in its reciever that it makes it unresponsive, again you dont want it hooked directly to the other system.

In ANY of these situations, with totally seperate systems, you loose half your controls and you land. This is a no brainer... I dont care who wrote the article or what he has done in the past, he is obviously very wrong and misguided on this subject. No one knows everything.

The plane pictured below has two completely seperate radio systems. When one battery went bad and died shortly after takeoff, flying this plane to a safe landing was no big deal. Had my two systems been hooked together, the problem would have been masked as the second battery took all the load and attempted to charge the bad battery at the same time. I would have lost ALL control and crashed on probably my second or third flight...

Dual radio setups should never be hooked together, kind of defeats the purpose of having dual redundant systems.....

JettPilot

My Feedback: (6)

Desertpig,

You did not pay attention to what rc bugman siad....

If you do lose one reciever and the controls on side of the airplane, it is a NON EVENT, as stated by rcbugman "The controls are just very soft "

The dual channel crazy thing with a friend is just something to try for fun and sharpen general recovery skills, but NOT typical of one RX failing...

No special practice is required to save a plane with dual RX's, its just like having everything on low rates....

sillyness

My Feedback: (25)

JettPilot,

That's why I have the fuse between the sides... protect from shorts. Also, LiIons with regs can't charge each other... the reg acts like a one-way valve.

jmiracle

My Feedback: (9)

Sillyness has it nailed. Jumpering power (only power!) between 2 rx's just makes good sense


You are correct that most failures are caused by batteries or switches....and then it's usually a short. If the jumper between the rx's has a fuse installed, then the fuse will blow when the bad batt shorts. Then you still have 1/2 an airplane to attempt a landing.



I would hope you check your batteries before and after EVERY flight. If you're doing this, then a bad battery can't hide. Also as sillyness stated....a typical setup uses li-ion batts on regulators. The regulator will not allow the good battery to attempt a recharge of the bad batt. In this scenario, there is no change in how the plane flies (assuming one batt has only gone dead, not shorted out)....and you will find the problem before your next flight.



If an intermittent switch is creating so much noise that the rx it's connected to is unresponsive, chances are there is so much noise in the airframe that the 2nd rx is also swamped with noise. In this scenario, you're SOL I'm afraid. There are some failures we just can't protect against.

quist

My Feedback: (198)

I have seen it done and it does work. That being said I only use one receiver.

Leardriver

My Feedback: (12)

I promised myself I wouldn't post on this thread but I do have something to add. I was fortunate enough to attend the Joe Nall fly-in this year. About two weeks before the event I went out to my field with my 3.3M Composite Arf Yak to get in a little flying. I took off, did a trim pass, and came around and pull up into a loop..........the plane than proceeded to pull out very slowly! I should mention I was using my low rates (sequence rates). Well it was pretty obvious that there was a problem. The plane wanted to nose down slightly (just a bit) and was a little mushy. I came around and landed uneventfully...although it felt a little strange..but overall uneventful. During the downwind and final you could seen the left elevator "drooping" slightly and not moving at all. This was confirmed when we got to the plane. The left elevator was dead...nothing...it was if it both servos in that particular elevator half had been unplugged. I did not turn the power off and was dragging the plane back to the pit area when the elevator all of a sudden "sprang to life"! ***! So now the issue was trying to find the problem. We checked everything....every connection/wire, the matchbox in the elevator (which was my first first suspect), the power-box (which was my second suspect), and of course the rx. Everything was now functioning properly! I was going nuts because there was no way I was going to fly this thing until this issue was 100% corrected.

A quick note...I was running two Futaba 149DP which had just come back from Radio South for a check up, Duralite Power Box/2 4000ma lithiums, Smart fly equalizers (matchboxes) in the elevators, and a pair of 8611s in the stab itself.

Anyway, I checked voltage to the servos, to/from the Smart-fly, from the Power box (which was regulated at 5.9v by the way) to the rx......I spent hours trying to find out/make it fail again. Finally I decided that the most logical point of failure would be the matchbox and decided to eliminate them in the elevators all together and use the two remaining channels and simply mix them using the radio. It took no time make up two more extensions and do the programming in the 9Z. I was content that I had simplified the install and "probably" fixed the issue at the same time.

Well, I was making the final adjustments to the new setup with the radio when the left elevator simple lost power! I couldn't believe it! Only now it was everything connected to that receiver!!! Ok (after my little temper tantrum) I realized that this was good......finally it failed in front of my face. Ok...so now it is either Power Box or RX. I was honestly starting to suspect power-box but before I could get to the front of the plane........bang... it came back life!! ***!!! Now I'm really pissed. I check everything again.....PB voltage/signal, rx voltage, power to the servos..all of them! Everything is fine!!!

For whatever reason I started tapping on the PB..nothing. Then I did the same thing on the receiver and presto...failure! I had done this before with no success but this time it failed. Moments later it sprang back to life again without me touching a thing! Than, like magic, just the elevator went dead (on that receiver). I switched them from side to side and the fault was again reproduced on the other side( it followed the receiver). I swapped rx crystals.....no change. I finally swapped it with a different rx and the prob was gone. I could not make it fail again. I than put the original (bad) rx back and the intermittent failures reappeared. As a final measure I put in a brand new crystal.....the failures continued. Mind you this is hours of testing and swapping. I did everything I could to verify that the rx was bad...in every case it followed the rx. I bought a NEW rx and 2 new crystals and was satisfied that this was the end of the problem....and it was...for this half of the plane. As a side note the plane had about 70 trouble free flights prior to the rx failure. Also, this was the first time I had seen a rx fail in this manner...sometimes 1 ch would fail and sometimes all of them. But it did!

Now...off to the Joe Nall fly-in. I went for the week and got there a bit early. By Wednesday the Yak had about 10-15 flights on it and I was letting my buddy Pete Castine fly it as he wished (he flew down without a plane) and all was well. I was busy trying to get my new Super Xtra going when he came up and started razzing me into "flying a little". OK.....I took off and instantly something felt "wrong". I handed the box to Pete and he confirmed it and ended up landing it...uneventfully. As we suspected......the other receiver failed! I could not believe my eyes! There it was. In speaking with Jason Shulman he said he had the exact same type of failures right before the Masters last year.....including one right out of the box! I went and bought another new rx and and all has been fine to date. This was back in May by the way.

So what is the lesson here........my $8500 Yak would have been destroyed twice had it not been for a dual rx setup. And if the second rx was not in the Yak, guess where i would have been...In my brand new SUPER EXTRA!!! Yup......that would have made for a grand total of $15000 worth of composite confetti because the second one would have failed on the 15th flight or so. So am I believer in two rx! Your damn straight I am! Could something still happen...sure it can. But that is twice in one year that it was proved to me. I have spoken to so many people who have lost one rx and landed their plane without incident. It is not a guarantee by any stretch...but I know for a fact what is a guarantee is a crash if a single rx setup fails in ANY way. The first incident was the elevator only! Can you fly a plane with two dead elevator halves???? Uh...I can't. But I know I can with one....same for the ailerons. Can ya land a plane without the rudder..uh yea. How bout the throttle ( it will run out of gas soon enough...or if you have a chock/throttle kill on the other rx...). All it does is give you a chance. Electronics can fail no matter how expensive, what brand , or how new........$@#% happens!

I also wanted to say that the second rx in my planes is installed for no other reason than to split the controls in the event of a rx failure. I have a power distribution box (Duralite) that I really like ( it simplified my install by eliminating 2 regulators, 2 fail safe switches, and 3 matching devices...along with the additional connections and wires) It takes care of all power issues..that is separate discussion though. The second receiver is only there to split the plane in two...that is it. One receiver would fly it fine...with out the additional safety margin that I clearly needed.

Bottom line is that it is ultimately the individuals decision. I think it's short sited to run one rx for any reason and my experience has reinforced my position in spades. If anyone wishes to discuss this further feel free to email me as I have no wish to battle anyone here on this thread. Thanks...I'm out.

PaulP
"Leardriver"

PS- the guy that was with me during the first failure was Marc Vigod...owner of RCU. PM him also if you would prefer to hear it from an "outside" source.

famousdave

My Feedback: (61)

Moral of the story.... Use JR Receivers!

Just kidding.. although I have not seen a JR RX go bad, I have seen many Futaba's act up... maybe just because there are more FUTs out there though... plus there are not many dual JR setups these days ..


Lear - you make a good point... there are always pros and cons of every scenario. I know someone who painstakingly did all the same things you did on a 3M Super Extra - him and I set up a perfect airplane... we took it flying at the Johnson Valley OHV park only to have a freakin pelican hit his plane mid-air and take the whole fuse out as we watched in horror...

One can't plan for everything... since when do pelicans fly in the desert ?? Must be that California air...
DP

PlaneInsane

My Feedback: (5)

My friends plane had exactly the same thing happen last year with a 149DP receiver. Elevator went dead. He was able to reproduce the problem and sent the receiver in to wherever you send in Futaba stuff. It came back with a brand new antennae and the same problem!

Out of curiousity I opened up a 149DP receiver and was shocked at what I saw. A whole bunch of big huge components inside that all looked to be hand soldered together. I then opened up one of my JR955S receivers and saw exactly the opposite. Just a tiny little board with SMT. My point being that the 149DP receivers would and in my opinion ARE very susceptable to vibration because of the large and heavy components inside. I think this is one receiver that you need to go the extra mile in making sure it doesn't get any vibration transmitted to it.

Leardriver

My Feedback: (12)

a pelican midair huh? That really is a new one....lol! I think my new hobby would be pelican hunting[>:]!! As for failures I think it is split right down the middle...I have had both fail. Team JR likes to spout off about the single rx argument trying to make their point about how reliable they are...and overall they are..thank god! But it all comes off as a marketing campaign to give the perception that theirs is the best/most reliable and buy JR. In truth Futaba, Airtronics, and JR are all very reliable. The range argeument is a stupid one because I can fly my 3.3M Yak to edge of my ability to see it and maintain control....and it is about as big as it gets with a few acceptions (131" wingspan)....and yes I have 20/20 before somebody plays that card! Lol!

Pelican takes out Comp arf...huh....whodathunkit????[X(]

PaulP

JettPilot

My Feedback: (6)

Paul,

You miss the point. JR is a much better receiver than Futaba or Airtronics, period. Sure Futaba and Airtronics recievers may be very reliable, but JR is much more reliable than both Futaba and Airtronics, so JR is the obvious better choice.

As far as range, JR receivers have superrior range. You may not fly to the limit of your range, but the JR is the more sensitive receiver, so that means that you have a better and more solid signal to the reciever even at medium ranges with the JR... At medium or further distances the Futaba would have a weaker signal, not good !

So with the JR recievers you have:

BETTER SIGNAL
STATE OF THE ART TECHNOLOGY
MORE RELIABLE
BETTER CONSTRUCTION


You would have to be a [sm=bananahead.gif] to use Futaba, or Airtronics, or Hitec radios.... And unfortunately, there are more than enough [sm=bananahead.gif] in this world to go around !!!

JettPilot

My Feedback: (6)

No , it does NOT make good sense... Having the fuses and dual regulators and a fues helps, but it still creates a bad situation.

With jumpering power between two RX's - if you have a regulator, or switch go bad, you may never know it, until you run down your remaining battery completely and crash. Hooking power systems together may hide a problem until its to late, then you end up without power and you crash [:@] Battery tests are not perfect, maybe you would, or maybe you would not catch a hidden problem by testing your batteries every flight... I for one do NOT test my batteries every flight. If something goes wrong, one side dies and I land. With seperate systems, I catch a problem EVERY time, a problem is NEVER hidden...

You may have a servo stall to the ponit on one side where it drains a battery pretty quickly, but does not draw enough current to blow a fuse. Again, with power systems hooked together, you can end up running down BOTH batteries and crash before you realize you have a problem [:@]

If you have noise induced in one system by something comming loose, noise generated directly into the wires of a system is MANY MANY TIMES stronger than noise passed over the air. Noise induced directly into the wires of one system will NOT necesarily be strong enough to disable a completely seperate system. If there is intermittent connections or something that induces noise into one system, you can be darn sure I want my systems completely seperate, not hooked together by wires !


So in the end, by hooking up both power systems, you end up with a more complicated system, that can still hide problems and cause the loss of BOTH sides of the airplane and result in a crash. There are many disadvantagtes to connecting the power on both receivers, WITH NO REAL ADVANTAGE over the completely seperate setup.

Again, its a no brainer. If you understand the issues and the different possiblilties and possible failure modes, it is far better to have two COMPELETELY seperate and INDEPENDENT systems. So no one failure is ever passed to both systems.....

Leardriver

My Feedback: (12)

Well JettPilot...sounds like you got it all figured out. Good luck with that...

Leardriver

JettPilot

My Feedback: (6)

There is right, and there is wrong. Contrary to what our politically correct society likes to teach us, when someone is wrong I point it out in no uncertain terms. No one knows everything and we are all wrong from time to time. Some people are smart enough to take it like men, stand corrected, and learn from it... I totally respect that !!!


Unfortunately, the vast majority of people are small and patethic little individuals that cannot get over the fact that somoene told them that they were wrong. They will post any response to distract from the subject at hand, instead of admit being wrong.... That is pretty sad, and that is not the type of person I would ever want to be...

JettPilot

jmiracle

My Feedback: (9)

Got any proof of that statement? Somehow I doubt it.

sillyness

My Feedback: (25)

Wow dude... that really speaks to your character and narrow mindedness, now doesn't it?! When does your book come out? You know, the one that tells us pathetic writhing self loathing little individuals how to live our lives? Be careful what you say on these forums... you never know who you are talking to. There are some downright incredible people that browse this forum on occasion.

As a side note, I'd really like to meet your wife. How's that marraige going?

Anyway, I'm not going to touch you with a ten foot pole... after that incredibly narcissistic statement I've determined that you are no longer worth my valuable time. Good riddance.

As far as some worthwhile points that were made in previous posts:

I check my batts immediately after every flight and I never fly them below half full (I generally only have time for 3 flights anyway)... works well, lasts a long time.

I won't freak out say you are dead wrong (as you may), but you really should check them.

This is true and it is a weakness of the system... these setups are nothing but balances of compromises. What would have happened to Leardrivers' plane if he was lower and didn't have the remaining elevator authority to pull out? Pick your evil and embrace it.


A friend of mine just told me what his setup is and I really think it is one of the best I've heard of yet! 2 RXs and 2x1650 NiMh batteries on EACH RX. This is in an Exclusiv Modelbau 40%ish Katana. Pretty smart.

Anyway, I can't take any more of the arrogance on here... I'm going to sulk away like the spineless amoeba I am and sell off my computer and all my planes since they are apparently all wrong.

Cheers Mates! I'm going to bed smiling tonight!