Carroll-RCU

My Feedback: (43)

This is my first try at this dual set up. I am using the 9C radio and R138 receivers. I can set the ailerons on ch. 1 on one receiver and ch. 7 on the other with no problem. The book says to use ch. 2 and 8 for the elevators only. The 138 only has 7 open channels.

Can I just split the elevators so one side will go to ch. 2 on one receiver and the other side go to ch. 2 on the other receiver?

Can the same be done with the ailerons as well?

thanks for your help on this matter,
Carroll

bob_nj

My Feedback: (62)

You would forfeit some of the benefits of splitting them such as sub trims, differential and matching total throws. What plane is it?

Forgues Research

My Feedback: (7)

Why use two receivers in the first place?

Carroll-RCU

My Feedback: (43)

The plane is a Aeroworks Extra 330L.
Never had a receiver failure but have heard two would be better due to the amount of money Invested in this size plane. I'm not real concerned about a receiver going out though. One would certainly simplify the set up.
Thanks for the replies.
Carroll

Forgues Research

My Feedback: (7)

Receiver failures are extremely rare, and the ones that have failed have probably crashed and not sent in for verification and simply reinstalled, not good idea.

What I have found, is to use one receiver with its own battery, and have the servos run with there own battery. This way the receiver gets the best quality voltage, cannot feedback into the receiver in case of a bad servo, which means better range also.

http://www.geocities.com/roger_forgues/batteries.html

Oh yes, good installation, and good regular maintenance is a must.

bob_nj

My Feedback: (62)

I fly a kit version of the Aeroworks 106" Edge. It has one receiver and one battery. Been going strong all season. You just have to find your comfort level and go with it. My pet peeve is keeping my planes as light as possible without compromising the integrity of the airframe_bob

Carroll-RCU

My Feedback: (43)

My Extra 330l is the 104" size and also the kit version. I also have the Aeroworks 33% Edge 540T which is about the same size.
I will most likely use the single receiver but I'll use an extra battery for backup.
What servos are you using on your Edge?
I have the JR 4721 for my Extra but am thinking of switching over to the 8411. The 4721 seems to have some side slop that I really don't care for.
Carroll

bob_nj

My Feedback: (62)

WHen I bought the plane it had all (6) 4721's in it. I too didn't care for the gear train wear and changed the ailerons to 8411 since the kit version uses only one servo per aileron. Don't know what it is with those 4721's though, but I go through gears too. The plane is light and shakes a little. The prop is balanced etc. Just the nature of the beast I guess

flatfour

My Feedback: (8)

I am curious why you say this. Just wondering if you are aware the battery can be plugged in to any open spot, or if need be, put on a Y harness with a servo.

Carroll-RCU

My Feedback: (43)

Jim, your right! I did notice a B & 8 printed where the battery lead usually plugs in. I could use ch. 6 that is not being used for the battery slot. I may look into this tomorrow.
Thanks for the tip!
Carroll

CMG

I may be missing something here but I fail to see how two receivers will save ANY airplane.
If you say split the airplane into one receiver takes care of the Left and the other takes care of the right. Now let assume you lose one receiver what happens when you move just one elevator ?

You will be very lucky to land it in one piece with just one aileron working as well, you a better man on the stick than me!

Us jet pilots have lots of $1000 and we only fly with one receiver.

Just use good equipment, as your self when you try to cut corners on lesser quality products it it Worth losing the plane to save $50?

Just my spin on it.

Carroll-RCU

My Feedback: (43)

Mark, You make a good point but, I did see a 37% Edge lose the left side receiver due to a bad crystal. The pilot was able to land the plane in one piece on the right hand receiver which controlled the right hand ail. and elevator including throttle. If it was a single receiver, all would have been lost. But you cannot compare an Edge stall speed or flight characteristic's to a jet. Maybe he was real lucky but, he did save the airplane.
Just my view...
Carroll

Forgues Research

My Feedback: (7)

You also make a good point, but what if your TX goes, what then??

Carroll-RCU

My Feedback: (43)

Lose the TX, lose the plane unless.......by chance you have a spare close by on the same ch. and setup. ....Probably not.
Of course it all boils down to the fact that most losses are due to battery failure, not receivers or TX's.
Carroll

Forgues Research

My Feedback: (7)

I suppose it also boils down to good maintenance.

I use to do aerial photography with a Gas X-cell helicopter and I had a lot of money tied up in this rig. Everytime I went to do a shoot, I would visually look at every nuts and bolts, clevis, control rod etc. I logged everything and that chopper never crashed with 84 hours in the log book.
But 3 times during this period I found problems during the preflight inspection, that could have caused a crash.

With today's equipment, there should not be a crash caused by faulty equipment if everybody does there homework.

Remember when you or anybody started flying with a trainer that wasn't build the best we can and the equipment was entry level and not allways installed properly, I have never heard of broken receivers during those times of flying. So the secret is not to tell the receiver that it has been installed in a 40% aircraft

Joe B.

My Feedback: (1)

Aside from the debate of "why" use two receivers, with a R138 you have 8 useable channels. You can plug the battery into ANY open channel or if there is no open channel use a y-harness to hook a servo and a battery up to channel 8 (or some other channel).

As far as having a spare receiver, if not for the fact you can 'split' the servo power requirements across multiple receivers (a big plus with HD digitals) you double your chance of failure with two receivers and if one goes bad you're probably screwed anyways as if one elevator half goes full down you'll not have any real means to correct thes other than full up on the other half and hopefully you'll have enough aileron to counter (doubtfully). Also, once power is removed from the servos they have no holding power and would be prone to flutter/wind deflection so I'm not a big fan of dual receivers for the point of redundancy - at least not in the traditional setup. They do, however, help split the electrical load across multiple receivers which is a good thing.

- Joe

Forgues Research

My Feedback: (7)

This brings up another point. The reason people started to use 2 receivers in the first place, was to spread the load of all those servos, but the receivers were not design as a load bearing bus bar, and in many cases, where one use all digital servos ( a lot of them in 40%) in some hard maneuvers, if a PCM was used, it could go into failsafe because of the high current demand and the voltage would go below the normal.
By using one receiver PCM or PPM, no matter, and let the receiver do what it was designed to do and that is to receive the signal from the TX and distribut it to the servos only and not power the servos on top of that.
I use a small battery for the receiver (typical 300ma) and power the servos with there own battery (typical 2700ma) .
By using a separate battery for the receiver you will gain in range because the receiver is getting constant linear voltage with nothing to interfere.

Joe B.

My Feedback: (1)

Do tell more. How do you connect your servos to their own receiver? Do you wire the signal wire only to the Rx and the +/- wires to a common battery? Does the RX work like that? Does anyone make a 'battery block' that you can plug all your servo's into and a harnes that splits the signal and power wires accordingly?

Forgues Research

My Feedback: (7)

http://www.geocities.com/roger_forgues/batteries.html

2 wing pilot

I don't disagree with anything stated so far, but I know 2 receivers saved my 35% Carden. My problem was a battery conn. failure after takeoff. It took several tries to get it on the ground but did with no damage. Is it necessary, no, but I had the extra rec. so I put it in. A guy deserves alittle luck once in a while.

JL1

My Feedback: (93)

I have been using two Rx, two batteries and two switches in some of my more valuable airplanes for several years. On one occasion a plane was saved due to a switch failure. It was difficult to fly with half the controls but it was controllable.
With regard to the rarity of Rx failure, I have had two in the last two years but I caught them on preflight. Whether or not a two Rx system is worth it is open to debate but it will work and it makes me feel better when I have it :-)

Tiger

My Feedback: (7)

It sounds like those that had two receivers and two switches nearly lost a pane due to switch failure. If they had plugged both the switches into the same receiver, they would have only noticed a bad switch on the ground rather than fighting to save a plane with one side paralyzed.

I always fly with one receiver, two batts and two switches. I've heard that 90% of electrical failures are due to switch failure and then to batts. Adding more receivers adds more points of failure.

Hey, here's an idea, One receiver per servo?

Cheers!

mulligan

Anyone try redundant transmitters?... sheez.

rm

My Feedback: (27)

[QUOTE]Originally posted by kirpal
[B]I may be missing something here but I fail to see how two receivers will save ANY airplane.
If you say split the airplane into one receiver takes care of the Left and the other takes care of the right. Now let assume you lose one receiver what happens when you move just one elevator ?



I flew a 40% Aeroworks Edge through the IMAC Unlimited sequence a couple of years ago on one elevator half when my 2nd elevator servo came uncoupled during flight. Only time I noticed it was in an outside loop, I had to use full down elevator to push it over the top. Thought it was odd but didn't even realize what had happened until my landing approach where I could see only 1 elevator half was working.

The best example I've ever seen was at last years AMA IMAC Nats, when this guys right stabilizer bolt vibrated loose and the whole right stab blew off his 40% Carden Edge. He was flying away from himself, had to turn it around, flew down wind, turned base, and made the slowest, prettiest landing he's ever made, and the plane never made a bobble. Was interesting to see, and hard to believe, but it really happened.

Has nothing to do with 2 rx's but you can successfully fly these larger aerobats on one elevator half. I use to fly 2 rx's, but that was mostly marketing hype in my opinion. Now I use just 1 rx with 2 switches and 2 batteries. Haven't fried a rx yet running up to 10 digital servos on the surfaces.

Robert

elderair

My Feedback: (29)

Are most of you that are using two batteries plugging your switch harnesses directly into the Rx or are you using a battery backer. IMHO this backer is just another weak point. If you plug two 1600mAh packs into your Rx using two switch harnesses do you then have 3200mAh available? How about using a large mAh battery with two leads and dual switches? Since it sounds like it is usually the switch harness that failes due to vibration a five cell 2700mAh pack with two leads using two switches into the Rx may be just fine? What are some opinions. This system is for a 29% Edge with five JR digital servos. Thanks, Kent.