Someone please answer Crash90's question, because I am wondering how it's wired as well.....

Hi,
Sorry I couldn't answer sooner. I had a few things to do, but have some time now. This is the way My 35% RadioCraft 330LX (the plane in my avatar) is wired up. I have two JR 940S Rx.'s using two Fromeco Reliaswitches going into two Duralite Plus 6v regulators and Dual 3600 Duralite Plus Packs. I split the airplane down the middle lengthwise. One side is on one reciever/battery/reg/switch setup and the other side is on the other. On the left side I hook up the throttle, left elevator, and left aileron. on the other side I hook up the right aileron, right elevator, and both rudders which are tied and plugged into a smart fly Equalizer which has one input that goes into the rudder channel on the right reciever. If the right side is lost the rudder will obviously be lost, but rudder would not be a primary control in an emergency landing situation. If the left side is lost, I lose the throttle. If it's lost at flight speed, it is simply flown out of gas. If idle, it is landed. All one needs to get the airplane down without issue is one good aileron, and one good elevator. There is no aesymetrical yawing or any funky flying tendencies at all with this setup. You may notice a slight decrease is roll rate, and pitch rate, but it not a problem. My airplane is setup very soft and smooth for precision type flying and I had plenty of control authority to make a completely controlled and perfect landing when I lost the side at the meet I talked about in my previous post. It was completely in control and there was no incident or anything dangerous at all. In fact, the landing was very smooth. I flew 20 minutes later after correcting the problem. This is not the only way to do this...in fact I like the powerbox setup much better as it eliminates some potential failure points, and also has the advantage that if you lose something the the other 'side' powers both sides. There is a new powerbox made exclusively for Duralite Plus batteries that is an outstanding piece of equipment. It also has a failsafe switch that is electronic and gives a visual representation with LED's of the status of both power sides. It also has the added advantage of allowing multiple servos on a control surface without the need for using up all the channels and mixes in a radio. Only one input goes into the reciever and all servos are connected to that channel on the powerbox...the ports are amplified so that signal integrity is not lost due to long leads. The unit was used at the last TOC with great success, and many jet modellers rave about this unit. Now that the unit is designed with the new technology Duralite Plus batteries I don't think there is better setup made. I can't imagine having anything safer or higher performance. The dual reciver setup is a good one and I use it in my 35% 330 with peace of mind, but the new powerbox setup has some very distinct advantages that I just can't pass up for my new 40% project this winter. There are many ways to skin a cat so to speak, but this is what I have found to work very well for me, so that is what I recommend to others. I only pass on what I know works well. I know about the powerbox setup because a buddy that I fly with in the same class as me, and at the same club I fly at has one and it works VERY well. None is this stuff is cheap, but neither is an GS Aerobat. I only use the highest quality stuff in my planes. I don't skimp on airborne equipment because I can't afford failures. I work very hard to do well in competition and have faired pretty well. I could not do that if my equipment let me down. Failures for me are season enders. It takes many months of exaustive work to build and setup these planes so they fly correctly. It also takes many hours of flying one to trim it, and get used to them, and that is why I cannot afford failures. I am so glad that the redundancy I put in my plane proved to work when it really counted. You would not believe the amount of work that was put into that airplane. It saved that airplane, and for that I am very grateful. That's what I hope will happen when others have a failure. If I can save just one airplane (hopefully more) by telling what I did and how it worked, then that makes me very happy. I like to see people succeed and not have failures that cause crashes. Everytime I see that broken hearted look on somebody's face it hurts me just as much. Hopefully this will help someone...I really hope it does.

If anyone needs pictures to help them, let me know. I have a digital camera and would be glad to take pictures if this isn't a clear explanation of how the plane is setup.

I will add to the set up that I am using a choke servo so I put it on the opposite reciever as the throttle and either way, you have a way of controlling the engine. You can kill it or you have throttle no getting stuck at a speed that is in between flying and stalling.


Steve

Just a thought. Would it make more sense to reverse sides on the elev. For example. If the rx that controls the right ailerons and right elev would fail you are left with the left ail and left elev. Where if the elev were reversed. Meaning put the left elev servo on the rx that controlls the right ail. This way if the Rx that controlls the right ail and left elev would fail. You would have the right elev functional and the left ail to keep the plane stable?

Just a theory offered to me by a fellow flyer.
What is your opinion?

I don't get this. The airplane is either flying or it is stalling. There is no in between these two conditions. The only exception to this would be in 3D flight when the airplane is in a stalled condition while hovering. If you lost a side in that attitude with no airspeed you're pretty much out of luck. I don't use choke servos (though I did give it serious consideration) for one reason...a bad pot can leave you dead stick. In a meet that can really cost me. In practice it's possible to come up short of the runway. I really don't like dead sticking these big planes, and have never had to with the exception of the meet last weekend where I lost the side...actually it was not a true deadstick as the airplane was at low idle, but it wasn't really pulling any. It really would've been better if it had gone dead actually as it would've went farther and I could have brought the airplane a little closer to me on landing. hehe If the airplane has too much speed to land it is still flying I could easily fly it out of gas. It may be hairy getting altitude, but if it has speed that can always be exchanged for alititude. If the airplane is stalling, altitude can be exchanged for airspeed. If there is no airspeed and no altitude, the only choices left are to land or crash...hopefully not crash! In any of these circumstances a choke servo really will not help matters, and is why I opted not to use one.

Hi Crash,
I don't think reversing sides would make it anymore stable really as the airplane was totally stable with both sides on their respective recievers. As I stated above...there was no aesymetrical behavior at all during the emergency. The airplane flew flawlessly except for a minor loss of roll and pitch rate. Actually it wasn't noticeable in the air, and until I realized what had happened upon retriving the airplane I didn't even feel it in the air. It was only in hindsight that I realized the plane showed a slight loss of authority. Very stable and predictable. In fact i think that as the airplane slowed, the left aileron started hanging and the up elevator of the working side while flaring probably helped to keep it level much better.

For the flying or stalling question, I have had this happen on several planes. The Throttle servo takes a dump at a setting just above idle. Now you dont have enough power to go around or maintain altitude, but it has just enough to keep it off the runway till you hit the trees on the other end !!! In this case your only option is to set her on the mains then give it down and stuff it in. This never has the happy ending we would have wished for. This is why you have a choke servo, or a fiber optic kill swith.

Ahhhh, now I see what he's talking about. I've had this happen many times on smaller glo planes. On the GS planes it would be a piece of cake as they are much easier to fly. You simply fly a low approach right over the grass...hold it off with elevator and keep holding it until the airplane slows. If it still won't land it has plenty of power to climb. Another way is to side slip it and scrub off any speed with rudder back and forth that comes back after the plane is aligned back to the runway before touchdown, then roll it to the grass barrier or hit the tall stuff. In the case of trees, the side slip is probably the preferred way of doing it, but if trees were really close, I would be looking for another field. You have to make quick decisions sometimes with these planes, but also have to make the right one...just like in a full scale. Dumping the plane over is not even an option unless it was heading for people and I make damn sure that that doesn't happen ever. Airplanes get pointed away from people...airplanes that go after people are possessed and get destroyed as they should be. hehehe So far I haven't had one of these possessed airplanes, but have seen them. Some of these incidents have happened because the airplane was started at too high of a throttle setting and was not restrained. We all know that that one takes an IQ of about zero...which essentially equals total brain death. LOL I just fly the airplane...it'll either fly or it won't.

I fly full scale in some of the most unforgiving terain on the face of the earth... After having stuffed in one of those, I can tell you that when the S%^t hits the fan, you do not allways think or do the things you should. I sat around the hangar talking with other pilots about how can a guy in a super cub kill himself when you can hit the ground at 35 mph. I can now answer that question, however, I was lucky enough to live to tell the tale.

Redundancy can not hurt in any way shape form or fashion.

I see you fly in AK...at least I'm assuming that as bush flying takes a special breed. I think you did the right thing and made the right decision. Survival and coming out unscathed is first...saving the airplane is really secondary although it's what you normally want to do, but in an emergency that can't always happen. One thing I guess I've been pretty good at is handling weird things with airplanes. I've grabbed many airplanes at the field saving them with split seconds left. I just never panic no matter what happens. I get so absorbed in flying the airplane I can't. I have to fly the plane and just give it what it takes to do what I want it to. As you know from flying the full scales...the primary thing is fly the airplane first...everything is secondary. As for the redundancy, yes, I am all for it as I stated in another post. I don't classify choke servos as redundancy. They are just another thing to fail unless you have two of them, then you have a redundant choke setup. There comes a point where stuff just becomes dead weight. A failed choke servo in hover would definitely end in disaster...it would also cause a unwanted deadstick on a plane that was flying fine before the failure. The only controls that are needed to get the airplane down safely are one aileron, and one elevator...everything else is secondary. This was proven this past weekend as that is what happened to me. The redundancy worked, and saved the airplane. There was no choke servo in the plane and I can see no need for one. maybe two, but that would have to be one huge airplane before I could justify the added weight, and it would have to be one sorry flying plane like something that has nasty stalling tendencies at high angles of attack.

Tim

You neglected to offer any information on what failed in your model over the weekend. I am guessing power failure of some sort or something that caused the second system to go to sleep, maybe even a loose crystal.

In other failure circumstances things may not be so easily manipulated. Imagine a surface hard over, wide open throttle, intermittent response good and bad from one system. All of these additional scenarios are prevalent and can and will happen. Believe me its no easy stable flight thing when you have a control surface hard over and are fighting with mushy inadequate response from the opposite side of the model. Been here done this!

Just a thought; dual RX's offer very little redundancy unless you have an RX failure! Batteries fail occasionally (with todays products its actually pretty rare), switches fail and wiring connections fail weather its brain fade, inadequate rigging or? This is true with one two RX's. Dual batteries and switching systems are simple old news and quite adequate, IMO. There is something to be gained when more than 8-9 servos are used, as other stipulated. Modern day high end RX's have been burned down to failure and are capable of withstanding 20amps intermittently without issue, in fact sustained spikes above 30amps were introduced before failures occurred.

An effective alternative for two RX's is the use of Matchboxes or Smartflys Equalizers when servo count is high on specific channels and these devices offer the ability to use separate batteries, again.

I'm a firm believer in utilizing choke servos. These are no more likely to fail than any other servo on board, in fact I'd guess they last substantially longer as they are exercised much less than any other servo on board. Another safety feature with little to no reason to think they'll fail, IMO. I like to use mine to start the engine too, you can fire the engine, choke-on and flip the switch all in one starting effort. Or you can use some other type of electronic or mechanical KILL switch system.

Modelbau's Power Box is has been refitted with a regulator able to handle the higher static voltage of the Lithium-Ion technology and a new switch assembly (Emotec is releasing there refitted unit in September, same reasoning), probably no secret bells or whistles. One can use the standard Powerbox NOW with the regulators in line, before the Powerbox same as your using them now (several TOC pilots used these as described above).

Something I am not clear on and in fact completely disagree with is Model Baus reference to "when one battery diminishes to the pre-set level the second one will immediately cut in and provide the necessary power-supply to the RX and servos. Utilizing Lithium-Ions in this scenario is not recommended... Both batteries must be on line with the high current demands that fourteen digitals servos can will require. This is the crux of the Lithium-Ion technology to date. What happens is under load without adequate capacity the voltage drops well below the desired output. This the very reason these cells are series-paralelled wired. Two things are realized with this methodology, additional ampacity and power supply redundancy within a single battery pack (generally the larger packs are comprised of two pair of two cells in series-parallel configurations). Hopefully this information is relevant to the earlier models for NiCd/NiMH applications or a typo/translation issue. In any event I don't agree with the concept.

The only redundant feature offered with the Power Box system is battery ganging to the power buss. Both Emotec and Model Bau offer single switch failsafe ON system features. Redundant power sources are available in several different methods for our systems without benefit of these gadgets. Some like the KISS concept. One could argue that all this additional gadgetry introduces several additional failure modes! And they would be correct, IMO. I am using the Emotec gadgets in my new models together with Lithium-Ions, plug "n" play wing and stab servo connections, custom built wiring harnesses and the works. Hopefully an ounce of prevention will amass pounds of good luck!

http://www.modellbau-deutsch.com/e/h.../power_box.htm

http://www.emcotec.de/download/download.html

QUOTE]Originally posted by Aero330LX
.... There was no choke servo in the plane and I can see no need for one. maybe two, but that would have to be one huge airplane before I could justify the added weight, and it would have to be one sorry flying plane like something that has nasty stalling tendencies at high angles of attack. [/QUOTE]

I would like to know when an engine choke servo would have anything to do with "one sorry flying plane like something that has nasty stalling tendencies at high angles of attack."

Great thread guys. I really appreciate the discussion.

Michael Glavin: Question about the powerbox; Agreed, you need to have both batteries sharing the load when you have a lot of servos. I like the idea of the powerbox eating the amperage instead of the receiver. Where is the battery redundancy in the system? It would seem to me that if one battery failed, the other would then be forced to pick up the load for both, and total power failure would then be imminent right?
Having just lost a 35% due to battery failure, I can tell you this is a sore spot for me, and my new 40% will have some form of true redundancy on all systems. Tell me more on why the powerbox is better than two receivers, I'm just not convinced.

Thanks
Roger

I see that my orignal post has become a popular topic! Thanks a bunch for all of the insight.... From what I have read, I believe I will run 2 receivers from now on. I think the extra 100 bucks is worth a $3K airplane.. Thanks, Jordan

Hi Michael,
I didn't actually have a power failure. I use only Duralite Plus Li-Ion's in my GS airplanes. I use dual 3600's and dual switches. The sides are totally redundant. There is no crosscoupling between sides, and this is what saved the plane. The incident was caused by a single connector that had there been only one reciever would've resulted in the loss of the model. My crystals are secured and I only use high quality JR recievers. This was not related to any type of equipment failure except for a simple connector. In fact, I've never had a radio related equipment failure since I switched to JR 18 years ago. I can speak for a model at wide open throttle...piece of cake...I simply fly it deadstick. It can get fast, but it's just a climb up and fly level turns thing until it runs out of gas. I had a rash of that happening on pattern airplanes with 3 different types of clevices I was using. I switched then to ball links that I secure with a wide washer that is larger that the ball should the link itself become dislodged from the ball and use double nuts and goop to sure the bolt. I cannot see this failing ever, and I use the same method only bigger on the ball links on my GS planes, and also on others that I build. As for hardovers I've never had one, and don't plan to, that's why I use only the highest quality JR gear, and have it checked once a year. Servos are slow and step tested once a month for bad pots as are new servos. As I said above, I've never found one bad in 18 years of flying JR. One day I might, who knows, but I can promise you that it will be on the ground. I check ***everything*** I can control and check on the ground. The one thing I cannot control is an intermittent connector or failed noise filter or crystal do to vibration. That is why I went with two recievers. It proved itself when it counted the most this past weekend. I will be using the new PowerBox Duralite Plus this next season and will be sending receivers in every 6 months for checkups. I have two recievers that will be rotated in and out in 6 month intervals so that there is no down time during checkups. I trust nothing. As good as my gear is I still trust nothing. As you know this stuff MUST be checked or it could be a disaster waiting to happen. I only fly when the airplane convinces me it's ready to fly. I have a 20 minute routine that I go through before every flight...even the wheels are checked. I knew long before this happened what would fail and was ready for it. You have to FLY the airplane no matter what's going on, and if you cannot control it there are only two reasons...it is uncontrollable, or it's beyond the pilots abilty. In the second case, the pilot should not be flying an airplane that is beyond his ability to control in the first place. You said it in a nutshell in your post...prevention! This stuff has to be checked it cannot be trusted at all. The only way I know to check connectors it to pull them once in awhile to make sure they make good tight contact and to shake and flip on them to make sure the wiring has not come loose and become intermittent. In this case it didn't prove to work, and I've had trouble with connectors before...this is why I say I can't really control those failures. I do know that all the power connectors on the PowerBox are isolated...should one fail or even be hard shorted the rest will still work independent of the others. This is one of the things that convinced me to get the unit because in the instance of the hard short scenario a reciever buss would more than likely be fried. Like I said, there are alot of ways to power these things, but these are the ones that work for me. With all of them there are risks, but you have to weigh the risks and what you can do about them. In just about 90% of the failures I've seen where crashes occured the pilot panicked and made a bad decision and most admitted it by saying "I shoulda' done 'this' or I shoulda' done that" I've only seen one recently where I don't think anyone in the world could've saved the airplane and that was a Rudder hardover on a FC. The pilot had it for awhile in KE but it was just too out of control to get down in one piece, and the airplane eventually spun in. I like the dual recievers, and now have complete faith they will bring my plane home, but now that I have seen the new Duralite Plus PowerBox I believe this will be the better setup for me. I will be using long leads and the Duralite Plus PowerBox no longer requires the use of ferrite rings. It has signal amplifiers built into the unit. It also has built in regulation of the current down to 6 volts which elimintaes the need for external regulators. That feature alone eliminates 4 connectors. When I compare the features of the PowerBox to what I am using now it just has so many advantages I can't see passing that jewel up. I also like the way the electronic push on push off switch is made and the fact that it fails on. It's also made so that dirt and debris cannot get into it. Just a little better design than a mechanical slide switch. The fact that it can withstand 20 A is also pretty amazing. These are definitely grand times we're living in. I remember a time when you took a model up and if you got it back it was a miracle. Now we have soooo mnay safety features built into these things that failures that result in the loss of one are very rare. The power systems are leaps and bounds beyond what they were even 5 years ago. I am very grateful for that fact as I said above in an earlier post. That airplane will soon be relegated to 3D only duty, and will be somewhat modified to do that type of flying at maximum performance. After I get the 40% up and going I will be getting a a set of wings cut that will be solid sheeted, and have some CF added to withstand high G stresses. I will also be incorporationg some added phenolic support through the use of sub ribs. The ailerons will be lengthened and lightened and all controls will be highly beveled for EXTREME throws. I have a B&B Smoke system that will also be installed and also have a few lightening tricks I am gonna do before recovering it. The new 40% will be for IMAC sequence flying only. Well, this is about too long winded and is really going onto other topics so, talk at ya later.

Aero330LX,

Could you be a little more specific. What single connector failed.

Tracy Hill

For simplicity sake and to not cause confusion I would rather leave it what was posted, but suffice it to say that the connector mentioned had it been plugged into only one reciever (which it actually was and caused the side to be lost) it would've resulted in the loss of the airplane. Instead of losing the *only* side, I lost only one of two sides. In this circumstance the sides of the airplane being independent of of each other is what gave me control to bring the airplane back. Had there been only one I would not have had any control. I would really have to post pictures to describe this, and I just don't have time to do that really. The setup would have to be removed from the airplane also to see how it is run, and I have a bunch of meets coming up as well as the Regionals which I've qualified for and don't want to do anything like that to the airplane at this point. Maybe this explains it a little better. Gotta get back to work here.

Wow, what a dissertation. After wading through that one I can only say a couple of things. If it is electrical, it will fail eventually and all the checks on the ground cant stop it. Yes you will find the obvious ones, however, the very nature of electrical failures prevent you from finding them all.

Just because you chose to buy JR does not mean in any way shape form or fashion that you are immune to electrical, receiver, or servo failures. Last season we had a H9 Cap with JR gear less than 2 weeks old that had a servo (8411) failure on the right aileron that resulted in the aileron going to full down deflection (one of the rudder servos went belly up 1 month later). Things were interesting for a couple laps till the pilot was sure he could land it, and he came on in without incident. I myself have landed several planes with this condition, I have also burned in a few that were just not savable. My Edge went in last year after the left elevator servo went to full up deflection while inverted. The amp gave out and that was all she wrote. In this case, with an elevator half at full deflection (62 deg.) you, myself, or chip Hyde will not bring this plane home in one piece, it just ain't happening.

This thread is getting off the original topic so I will go no further....

I agree with you akflyer. To have this misconception that just because you have two totally separate systems that will save your plane if one goes belly up, is shallow thinking. But maybe I am the only one here that would have trouble flying a plane that had a rudder, aileron, and elevator hard-over with full throttle.

Aero330LX....would you please answer the question intended for you about the choke servo? Thanks

Aero330LX,

This thread is about 2 receivers. The other common alternative is 1 receiver and 2 batteries and 2 switches. Since the normal setup is each elevator on a separate channel and each aileron on a separate channel. I'm trying to figure out how a 2 batteries and 2 switches system can be shut down by 1 connector failure.


Tracy Hill

Hi,
As far as choke servos, I don't use them...never have, never will. There is no need for one. It is simply something that can cost you a round and has with others before. I'll be damned if I put something like that on my plane. There is absolutely no logic at all in that. With the season I'm having I'd look like a fool if something like that cost me a round at a meet. One bump of the choke switch and you are deadstick. A servo failure will also result in a deadstick. That's not even considering that there is another one of those plugs in the mix that cost me a round this past weekend. It's a simple task to reach under the cowl and pull down that choke rod, flip until it pops, and turn it off. I don't need a choke servo to do that for me. Once it's off in the detent it cannot close and cause a deadstick. Why on earth would I want to add the dead weight of a servo to my airplane when a piece of nyrod that weighs less than 2 grams works just fine? There is no need for a servo to actuate the choke. We can sit here all day going through 'what if' scenarios, but those have been well covered on my airplane while it was on the bench, and the ones that haven't I am perfectly aware of and am perfectly capable of handling by simply flying the airplane. Everything on that plane was well thought out *before* it was done. There was no afterthoughts added. In fact, 2 years was spent on a scale-aerobatics list learning these planes and HOW to do it right from people who had done it longer than me and through other successes and failures. Everything that was done, was done for a reason, and everything that was not done, was not for a reason. So if you call that narrow minded I would hate to see what you cognitive reasoning! LOL I just saw a post that stated there was 62 degrees of deflection on a control! I also read where it failed...gee, I wonder why? Give JR a call and ask them why they see hardovers...you will get two answers. 1. Overdriving the servos resulting in damage. and 2. Binding from improper setup (not matching the servos) which resulted in damage. Was that the servos fault? No. Do they eat a bunch of these failures anyway and fix the problem anyway be replacing servos FOC? Sure do. I also don't remember stating anywhere in my post that I was immune to failures because I use JR gear. In fact, I stated that I send my stuff in once a year to be tested regularly with equipment that I don't have so that doesn't happen. This stuff will go a year of flying and has done so 18 years running now. I think that record should speak for itself. That didn't happen by accident or by luck. Treated properly JR servos are the top of the line. I am also aware that there are people out there that would have trouble with an on/off switch if there was a way to make it fail, but I am not in that category....thank god! heh If you read and study up on this stuff and check it, it is reliable. It is cutting edge stuff though, and if it's not setup right it will fail. I read all the time about setting these planes up in hours and see the red flag already. It doesn't take hours to set these planes up right, it takes *days* and *weeks*. It can easily be tested for binding with an ammeter also. The use of a servo matching system such as the Smart-Fly equalizer or the JR matchbox is not an option, it's a requirement. A simple slow, and step test WILL show a bad servo on the ground. I'm well aware that everything has a failure rate, but when you travel around to meets, and you fly these things for years you realize that the failure rate of JR gear is very very low...darn near non-existent. That is why I use it, and is really the MAIN reason I use it. If there were anything any better out there that showed as much reliability and performance it would be in my airplane. So far I have not seen anything like that available. Money is no object on my planes, only reliability and performance. I don't care what this stuff cost, and I don't screw with junk. Most of the problems I have seen are caused by improper setup because the user is not even aware of what does cause problems. When the digitals first came out guys were cooking them left and right because they were binding, and it wasn't until later that it was realized that even 1 degree of binding can cause damage that will cause the servo to fail. There are people still to this day that swear that you cannot put 8411's ganged on a rudder without them oscillating, yet I've had this very setup on my plane for over a year and half now with not a hint of it. The cause? Again, lack of accurately matching the servos which causes accelerated wear and then 20 flights later the servo starts overshooting trying to find center which is actually what it's supposed to do. The user then blames the servo for wearing itself out even though there are countless others who have theirs setup right and do not have this problem at all. That last issue became so ingrained in people's minds online that JR had to detune the deadband of some peoples servos which is where part of the precision comes from. Mine are not detuned, don't have oscillation, and the original servos are still going strong after 100's upon 100's of flights. Is that an accident? I don't think so. Some of this stuff is needed for an added level of safety, but some of it is really unnecessary. Like was stated earlier this is getting wayyyy off topic, and I have much work to do. I will say no more on this issue, but will move onto to other topics here on RCU later. This has been good discussion as I believe it has cleared up a few myths.

I would like to know when an engine choke servo would have anything to do with "one sorry flying plane like someting that has nasty stalling tendencies at high angles of attack." [/QUOTE]


Aero330LX, You have some good points there, and you may do things the way you prefer, but even with all those words you just skated around the question I have asked. Could you please enlighten me on my above question to you?

One of the myth is that choke servos will get you a zero or something of that nature,

There a lot of people using a choke servo with no problem and won't have a problem.
Most of the Fiber Optic servo extensions I sell is for the throttle and CHOKE servos and I sell a lot.
Choke servos do work and very well may I add..

Redundancy is achieved by utilizing two batteries. The batteries are isolated from one another. BUT if you have a scenario that dumps the batteries there is little to nothing that can save your model other than luck and getting down before the lights go out! Of course this scenario gives cause to the two RX system with independent power supplies. IMO this is an unlikely event but I am sure that it has happened. I'd be willing to bet that if it did happen it would be somethingthat was modeler introduced, i.e. wiring, chafing or improper setups.

RX's in todays world rarely fail if there properly cared for. Two RX's does offer some perceived value in this regard. The real reason the two RX systems offers redundancy is, the two independent power sources. If you utilize a power jumper from one to the other RX you have increased the odds in your favor two fold, IMO.

Simply put the power supply connector that failed in Aero330LX's outing would not have been realized until such time that the model was on the ground and proper systems checks were employed with a single RX system utilizing two power supplies or with the use of a power box device. I guess redundancy is in the eye of the beholder.

One of many reasons I believe the power boxes excel is the ability to regulate, isolate, amplify, offer failsafe on features, eliminate wyes and allow the use of extensions to each servo used in multiple high current draw applications from a single signal source (no more mixing in many cases which can lead to lag time between servos/surfaces). Together with the use of programmable servos the sky's the limit, IMO...

Of course there is something to be said for the current handling capabilities of these devices! Which is sorely addressed in most other scenarios.

Not trying to convince you to use a choke servo, as you have your mind firmly made up. However, for the sake of others who might be interested, here is my 2 cents worth.

Choke servos add convenience and safety. Ignition kill switches add to the safety factor, but do not really add much convenience. No matter how you setup your throttle servo and linkage, failures can, have, and still will happen, and leave the pilot without the control he originally had.

If the throttle servo itself fails, the choke or ignition kill switch can turn off the engine once you've lined up on final. Much less risky than trying to fly it out of fuel, especially in tight fields. Further, depending on the throttle setting, the contents of the fuel tank, and the remaining capacity of the batteries, you may find your flight time outlasts your remaining battery capacity. I've seen this happen a few times.

The muffler can loosen up at the header, crack, or fail such that the dynamics of the engine change and the throttle linkage no longer controls the engine rpm correctly. You can easily end up with a very high idle at your lowest throttle settings. The choke servo or ignition kill switch would be able to kill the engine once you've setup on final approach. I've had this happen to me, and see it happen to others.

The firewall can separate for many reasons. Engine vibration from a split or broken prop, spinner failure, engine failure, ignition failure, etc, not to mention loose engine mounting bolts, failure of the engine mount itself, or failure of the firewall installation. Once the firewall becomes loose, the throttle linkage becomes unreliable. I've seen one case where an engine vibration loosened up the firewall in flight, and the pilot lost most control of the throttle. We was attempting to fly it around until it ran out of gas, when the vibration finally ripped the engine assembly of the airframe, and the pieces fell to earth in different directions.

Many of these things can be prevented with proper maintenance and inspection, but things still happen no matter how careful you are, or how good the equipment is. There are things you just can see in order to avoid, and are just lying in wait to get you. It's easy in hindsight to say they could be avoided, but how can one tell that a brand new is getting ready to fail? Or a hairline crack that is not visible to the naked eye is going to break under stress in the next 6 flights? Or that a brand new $200 receiver has cold solder joint that happened during manufacturing, and will fail in the first 30 flights. Or any number of other hidden failures waiting to happen? We can't, so we improvise where practical and appropriate, be it dual receivers, dual redundant batteries, choke servos or ignition kill switches, split ailerons, floating bellcranks, etc. They all serve a particular need based on the specitic pilots concerns.

The choke servo solution is very practical for many, as it also provides many conveniences, as well as a safety backup for killing the engine should the throttle linkage not be up to the task. The same can be said for the ignition kill setup. I use both in my airplanes, and have never had a failure of either. And yes, one could accidentally bump the choke or kill button and cause a dead stick. One could also accidentally bump the 3D rates on final approach with much more deadly results. Its up to the pilot to know what their switches do, and use them at the appropriate time. When flying that class of plane, I would assume the pilots are up to the task, and can use the appropriate switch at the appropriate time, and/or program in an interlock to guard against accidental activation. Even if tripped, the pilot usually has a few seconds to turn it back off before the engine will go dead stick because the prop is still turning and windmilling.

Regarding your failure, it sounds as if you lost your power connector to one receiver, leaving you with the other side to fly the airplane. Its good to see that you had no difficulty in landing your airplane, which is the whole idea behind the dual receivers setup. Many have said that it would be impossible to land an airplane in that configuration, and they are usually the ones that have never had the experience. While I can't say I've had the pleasure of doing so myself, I have seen others do so, and have heard of enough stories that were verified to convince me its a very good strategy, and I balance it with with fact that receivers rarely every fail. While you had the easy failure mode, things would be more dicey with a surface hard over, or nearly so. This is where using the left aileron-right elevator and right aileron-left elevator crossover would come in handy, and help to minimize instabilities in some cases. In cases where its not needed, it would have no adverse effect, so why not.

Unfortunately, there is no way we can ever say we will not suffer a receiver failure, throttle servo or linkage failure, loss of power because of the battery, switch, wiring or connectors, crystal failure, or just about any other flight control or electrical component. No matter how hare we try, there are always hidden gotchas. All we can do is design with certain failure modes in mind, maintain the airplane properly, and add redundancy where practical and purposeful. The rest is up to murphy, as there is no zero failure airplane