I have noticed a lot of guys flying dual receivers in there aircraft. What is the real advantage of flying with 2 recievers? I can understand 2 batteries ,but 2 recievers? If you get a radio hit or someone shoots you down its going to effect both receivers. I have been flying RC for many years and I cant rememeber one time that I have had a reciever problem. If you fly 2 recievers you might as well have 2 transmitters, because what if your transmitter bites the dust? Just curious........

Redundancy...all full scale aircraft are designed with at least one redundant system. On a 757 there are a total of seven hydraulic pumps. And if for some reason both engines and the apu fail...there is a ram air powered pump that allow control of the ailerons and elevator.

Look past just radio interferance when you ask about having a second rx, like the second servo on each surface, batt, switch, wiring, and so on.

Sorry, I see you took into consideration for a battery.

I understand redundency to the fullest,I fly a jet that has tons of redundant systems for a living(not as many as a 757) .There has to be a better reason why people are using 2 recievers. What fails in a reciever? Its solid state... overvoltage could do it maybe? No.. nothing can cause overvoltage in these things. The main reason rc airplanes crash because of a radio problem is 1)Radio interference 2)some nit-wit turns his radio on. Two problems that 2 recievers wont make a bit of difference in. I have heard of everything in an RC aircraft fail, except a receiver. I have been told its because the larger airplanes 35% and up need to split the load of all 15+ servos between 2 receivers because 1 reciever cant handle it all.(does that sound right) it does to me... You can have 10 receivers in your airplane, and still stick your plane in the dirt because your one and only transmitter just decided to bite the dust.I am ranting and raving, sorry, just looking for an excuse not to buy another reciever. It's cheap insurance I guess......well not really too cheap.....

By the way..are you an AMT for AA ? If so, I am looking for a buddy of mine that you may work with....

Nevermind ..your with Delta

The reason I'm using 2 receivers is for the extra channel output. Since I'm using matchboxes to handle centering and endpoints of the servos, I can use the aileron and aux1/flap outputs in each receiver eliminating the use of y-connectors.

In my H9 Ultimate I have the top left wing going to Rx1 - aileron, and the top right wing going to Rx1 - flap. The bottom left wing goes to Rx2 - aileron, and the bottom rigth wing to Rx2 - flap.

Quique only used 1 receiver at the TOC last year and his Yak has 17 servos in it.

-Doug

JR,
I have all the same questions you have. The only technical reason I've heard is the need to split the electrical load. And I'm not sure just how valid this concern is. It would be interesting to open a receiver and examine the size of the conductors.

I have always been suspecious that guys are "gold plating" their toys. Something which is not to be discouraged, only understood.

Tom

Thanks for the reply's guys!

The reason for gold plating is because gold has a very low electrical resistance. It's been a while since I've dealt with electronics, but not many things have a lower resistance then gold, and most of those cost alot more. Since conectors are a usual spot for higher resistance, you can gold plate them to try to help reduce it. Does it make a difference? Maybe. Will you notice it? probably not.

The main reason I use dual receiver's in my 35% planes and up is that I have landed a Plane with 2 receiver's in it with only 1 working saved a 3500 dollar airplane for the cost of an extra receiver. So I can not see not spending the money on it for extra security just in case something happens. Secondly as Doug says it makes it easier to hook things up without so many Y connections.


Steve Hill

I had a receiverwhich developed probs, but noticed them before taking off. Phew! Anything can go wrong, given enough time it will.

I have to echo Steve's Expierence. I had a 40% Extra lose a crystal that was found to be heat sensative 2 months ago, and was able to save the airplane.

Same reasons here. Some redundancy for flight controls if one receiver fails, as splitting the load is another. With the reliability of the receivers these days, is almost questionable whether or not the redundancy aspect is worth it. However, at $6-10K per plane, the extra $200 is real cheap insurance for me.

Both JR and Futaba only recommend connecting the number of servos to match the number of channels of the receiver. If you have a 9 channel receiver and 14 servos, its best to use two receivers. At least that is what the people that designed and are selling the receivers say, so I go with the flow

Or run one receiver and one of these...

http://www.modellbau-deutsch.com/e/h..._box_40-24.htm

Doug, can you explain how you can get extra channels by using 2 receivers. With two receivers you get exactly the same amount of channels...

I agree that one receiver is all one needs. A lot of people are going to 2 receivers because of the expense of the airplane, yet, with the smaller, cheaper, trainers which were most likely assembled by beginers, chances are that these receivers were not installed properly and and still never failed, so the receiver in the large airplane doesn't know the airplane is big, so it won't fail either.

The other point, with two receivers, having one side of the airplane on one receiver and the other side being on the other receiver, then that is a disaster waiting to happen with a false sense of security.

If one insists on going to two receivers, then at least go with a system that should a receiver fail for any reason such as batteries, switches and such, you would continue operating on all controls. dual redundency

I personally favor a single receiver but not connecting any servos directly to it, with having a seperate power supply for the servos.

power supply

Instead of having a two servos for one aileron connected with a y, each servo can be plugged directly into a RX. Imagine the load if you had a four servo rudder connected with 3Y's, going to the one rx, it must be better to split it across another whole system. How many amps can a switch handle. I was in a discution with Jason Kruase and he mentioned that his fury, with 4 digi's, gov, and gyro, will draw up to 5 amps. Now how about a 17 servo ultimate! It has to be up there.

I don't get extra channels, I get extra channel outputs to plug in my matchboxes, avoiding the use of y-harnesses.

Roger, I'm not trying to start a flame war, but I though you gave up on the true redundant receiver solution because of the technical issues with signal collision, not being able to sync the two receivers together, and all the bad things that come with that. Did you get them resolved?

Nope!!! I have been using it with great success all year, but I am reverting back to one receiver though.

The best setup I have seen with this, is with two IPD receivers.

I'm most likely going the single receiver route myself on the L39 turbine, with the Power Box 6 channel unit for power distribution(http://www.modellbau-deutsch.com/e/h..._box_40-24.htm). On the same token, I've heard of many credible stories of people saiving their airplanes with dual receviers, and seen one myself in person, that it makes it hard not to go the dual receiver route. We'll see what I actually do when it comes time to drop in the compoents. I still have lots of thinking time before I get to that point.

Guys,
I'm glad this came up. I just got back from the Triple Tree IMAC and lost a side on my airplane, and thanks to two recievers I still have it... it not only saved the airplane, I finished the meet and won it. I would rather spend a couple hundred extra to save thousands than sit through the rest of the year watching what I 'could've' done had I just put that extra rx. in there. I made a perfect landing on one side with no power and made my appraoch less than 5 feet over the lake at Triple Tree! If I hadn't had that other reciever, I would've been taking a swim to collect the pieces of what used to be my airplane. There is another solution to this...it is a powerbox, and it gives full redundancy without losing a side. I will be using one of these on my next airplane. I would never consider flying one of these expensive 35% and up airplanes without FULL redundancy. If you have one reciever with dual batteries, and switches you do not have FULL redundancy...you simply have a single failure point supported by twice the battery power...you are also doubling the load both of those batteries will be carrying. If the sides of the airplane are tied together in any way you have lost the abilty to control the airplane on one side, thus losing the redudancy that saved my airplane this past weekend. With a dual reciever system or a powerbox system you have a FULL redundant system. Aw, BTW...remember that these planes carry GAS...when they hit the ground hard that gas is just a little flammable. heh I think about how stuff can fail, and I eliminate that possibility from the equation when the airplane is on the bench when being built. That thinking has served me very well, and while this is an expensive hobby, it hasn't cost me an airplane due to any malfunction of the equipment in 19 years of flying everything from trainers to racers, pattern planes, and IMAC Scale aerobatic miniature aircraft. Not one single equipment related crash. I simply will not fly these things unless I am convinced they are 100% safe.

OK. So what is the proper way to wire a 2 RX system. Say with
4 ali servos (2 in each wing)
2 elevator servos
1 throttle
2 rudder (pull pull)
1 choke

I forgot one thing I thought I better mention about the powerbox I mentioned in my last post. I will be using a Duralite Plus version of the PowerBox. This version will be distributed by Performance Products. There are two versions of this unit...one for the older technology batteries, and one that supports the Duralite Plus batteries.