Goggles

My Feedback: (4)

Hi,

In the next month or so I'll start building my 36% Edge and right now I'm slowly getting all the hardware together. I was wondering how many people use dual equipment so I thought a poll would be in order before I buy the equipment.

A little info:
- My flighing skills are not quit IMAC Basic yet, however I do want to start learning all the right sequences and how to do them properly.
- The control thows will of the 3D variety with plenty of authority so in the future I will be able to go all out.
- The plane's weight should come in around 26# or so (others have) and will be using a ZDZ 80.

I was thinking of going single till my flying got more aggresive, then I might double up....what do you think?

Giant Scale

The question you have asked is rather ambiguous..for example I use a single receiver but dual batteries in my 35% plane. In my 50% plane I use dual receivers and 4 battery packs. It would be more informative if you asked these questions

1. single battery, single receiver
2. double battery, single receiver
3. double battery, double receiver

Just some food for thought.

kram-RCU

I always put 2 independent receiver/battery units on my big birds and cross-wire the ailerons and elevators. I'm not actually aware of any specific incidents where this has saved a plane for me.

I'm always a little nervous about where I run the twin antennae. Any advice or experience with that??

mt

Traxxas_Tech

My Feedback: (22)

In your 36% I would recommend two battery packs, two switches, (one for each) and two PCM receivers. You dont want to add too much weight. Split the plane in two. The way I do it:

First rx: Right wing servos, right elevator servo/s, and rudder servos.
Second rx: Left wing servos, left elevator servos, ignition kill (if applicable), throttle, smoke.

Since loads and voltage usage are going to be different, flip flop your battery packs every couple of months to keep them somewhat similar in condition, so they will age closely. Not absolutely neccesary, but most like to do this, especially lithium-ion users.

Hope this helps.

buyrbware

My Feedback: (2)

As you are out spending money on more equipment, Pick up a new corvette too! And send me $1000.00 while you have it to throw around.

1 reciever
2 battery packs (seperate Switches)
For your 36% that will be just fine. Maybe next we will be throwing an extra set of servos on the elevator or adding dual transmitters incase one fails.

OSilfa

My Feedback: (2)

I agree with buyrbware ,this is the best option

Mike Rojas

My Feedback: (2)

I also agree with buyrbware,works fine for me.
Mike

Traxxas_Tech

My Feedback: (22)

Jeez guys, Beat me down why dont ya?


I guess it would help if we knew how many servos he is running, and if they are digital. A 37% Sukhoi I'm working on nearly overheated on one rx/ two batts... But it has 13 digitals...

Whatever he can afford.

buyrbware

My Feedback: (2)

Thats the important thing. What he can afford! Guys often post here for advice and often take the advice to heart, or as to be gospel. I now that alot of times when I post here, if a senior member says to do something a certian way, I ussally take his word on it! R/C flying is suppose to be fun, not unrealastic to do! The thing we must remember is, can the guy safely fly his airplane with standard radio gear. If the answer is yes, Than we should not make it sound like he needs to dump a bunch of wasted money in to the sport just because the "Jones are" Dual recievers might have a point. but the aircraft will fly and fly safe on one. "For many years I might add if taken care of". Sorry this is just my opinion and everyone has one. The Gentleman " Kram" in the earlier post said it perfect. He stated that his aircraft flies on two, but has never proven to be saved because he uses two!

mulligan

IMHO, "afford" has little to do with it. No matter how much money you have to spend, I'm not sure the benefit of having two receivers outweighs the disadvantage of introducing more failure modes (more circuitry, cross-interference). I've heard very, very little of single receiver setups where a crash was determined to be the result of a bad receiver (unless someone uses a recently crashed receiver in a new plane without first having it serviced). By far, redundant batteries with independent wiring/switches is more advantageous.

My vote would be for two batteries, one receiver (please edit poll as suggested earlier).

- George

dork_blaster

My Feedback: (14)

I run a single PCM RX with dual 5-cell packs and 2 switches with a slight twist:

Instead of the servos (8 digital, 1 std) getting their power (red leads) from the RX, I made up my own heavy duty power distribution bus for each pack coming off a pair of heavy duty switches. (grounds are all tied together on another big bus) This setup hasn't failed me (yet! :surprised ). I think someone out there makes a commercially available power distribution system, but I'm good with a soldering iron, and I'm an electrical engineer (RF) by trade - so I better know what I'm doing!

I've actually seen, first hand, dual FM RX installations that cause more problems than they've solved - e.g. one RX interfering (causing servo chatter) with the other. I've NEVER had a new, uncrashed RX fail on me, but I've had servos go (and I don't think dual RX's will help a bad servo?) The reason I highlighted FM, is that a PCM RX would go to failsafe and you'd never see the servos chatter. I don't know a way to check for PCM RX crosstalk.

While I agree that dual RX's provide redundancy, I've never personally experienced or ever been told by any of my flying buddies, that this redundancy has ever saved their ass. Just the occasional anecdote here or there in this forum or that.

FWIW - the money for the 2nd RX was never an issue with me, just wanted to avoid RX crosstalk, and keep the installation as simple as possible. Also, I don't think the ORIGINAL reason for using dual RX's was for redundancy, rather it was to keep the power drain (from all those high torque digital servos) from whacking the Voltage to the RX circuitry, and redundancy was just a side "benefit".

Any who, don't spend all my $0.02 in one place!

Best regards and good luck with whatever method you decide to go with!

DB

MHawker

My Feedback: (16)

I've seen DB's set up. It's very slick and well put together. Give his idea some serious thought.

Mike

rctom

What do you mean "Nearly overheated"? How hot did it get, and what temperature is considered overheated? How did you measure the temperature? Do you have a temperature recording device in your plane?

TF

Traxxas_Tech

My Feedback: (22)

No, I simply sat and cycled the servos for 10 minutes, as if in flight, and touched the receiver when I was done. the cover was warm to the touch, twice as warm as the JR 950S in my 33% extra. This was in the "testing" stage, and was mainly for grins, but it made me feel better when I put in two receivers and noticed the heat was gone.

You range check a PCM receiver by constantly moving all the sticks on your transmitter, moving all the control surfaces and throttle. I have a couple buddies sit and watch the surfaces and see if they stop moving, (failsafe). If the receiver went into failsafe, I know I have to go in and find the problem. You can also tell which receiver it is by which side goes into failsafe.

locoworks

i have one receiver with an opto-isolator, and two batteries for each. ie 2 batts on the receiver and two on the opto-isolator feeding the servo's. i also have my ignition with two batts. the pairs of batteries all go through backer systems , so if one dies it doesn't take the other with it, and in theory, all keeps going. weight is the down side , its carrying around 800g extra for this luxury. all this is in the 33% hanger 9 cap. as i used the zdz80 twin, its heavier than it could be. i know on paper the twin is the same weight as the single, BUT, two little mufflers weigh around 35% more than one larger one

kram-RCU

kram-RCU

I recently learned a much easier and straightforward way to range check a modern PCM radio. Check the educational article in the latest Horizon catalog for details, but basically you pre-program the failsafe to dramatically up elevator or cut throttle in response to loss of signal, depending on whether you're testing engine on or off range.

On my JR 8103 system, turning these features on and off only takes about 3 seconds and can be done without turning the radio or the plane off. and, with the right kind of restraining device, you can do it without helpers.

shill

My Feedback: (22)

I Have personally landed a 35% airplane on 1 receiver working only had a receiver go bad and it was not that old and never crashed. I have also seen 2 other planes landed with only one side working . IMHO it is not worth risking the amount of money going in to these planes on 1 receiver with 2 batteries and switches. Weigh the cost of the airplane verses the extra receiver and building a new airplane when 1 receiver fails and that was the only receiver and not only money are you out when it crashes but how about the time to you put into building or finishing etc the plane. I do not like PCM it will hide problems you might have in your set up and can cause problems later. With PPM you will know from the start when range checking the airplane with the engine running if you have any problems. All of the planes I have 30% and up have 2 receivers and switches and batteries. weight gain from the extra receiver is minimal again to replacing the airplane. So here is some reasoning behind my opinion of 2 receivers, 2 batteries and switches. Also I have never had and interference problems from the 2 receivers interfering with each other and I have 2 fiber classics 35% extras composite fuses with 2 receivers and both antennas are run inside the fuse no problems with either.

hope this helps Steve

dork_blaster

My Feedback: (14)

Thanks for the compliment, Mike... how much do I owe ya? BTW - thanks for your help on the sound check last week. I almost have the new canister installed, should be a LOT quieter now, will keep you posted.

This thread has morphed into more than just a "dual equipment" poll but is proving to be quite useful (at least for me).

Thanks for the advice on PCM checking (KRAM and Coulter), I ALMOST decided to try the "elevator to extreme on failsafe" but then remembered how absent minded I am about unprogramming it AFTER testing. Can you imagine what would happen if I forgot to deprogram it and then got hit? Ah... didn't know you could do "the wall"

Then it dawned on me, all you need is a LITTLE bit of deflection (enough to see at range check distance) to see if the PCM is getting hit, yes? And if you use it on your elevator, coupled with low idle failsafe on the throttle, you want a little up on the elevator anyways (with a little bank) so it spirals slowly (hopefully). You could leave it programmed that way using this scheme and not worry about slamming full elevator.

Just thinking out loud. Apologies to Goggles for the off-topic discussion.

DB

vicarh

My Feedback: (1)

DB,

Could you post some pictures of your power distribution block? I have been think of building one but have some doubts about the best method (read materials, size, connections,...) to use. I have to always try an build it myself and if I fail then I go to the hobby shop.

Vicar

vatechguy3

My Feedback: (11)

maybe i should start a new thread for this, but i'm going to ask it here anyways.
a lot of you guys are talking about using 2 batts with 2 switches and one receiver. but how are you connecting the two power leads to the single receiver??
the only way i can see this working is by hooking both to the receiver, but then how does it only draw current from one batt??
i guess i'm confused about the whole setup.
can someone clue me in???
thank
tony

Traxxas_Tech

My Feedback: (22)

You connect both power leads from the switch, directly into the battery port and another spare channel. So you have two power leads feeding the receiver. Both battery packs feed voltage to the receiver, and they discharge at the same rate. If you use two 3200 mah packs, then you increase your capacity from 3200 to 6400mah with two batteries in a redundant system.
Hope this helps.

Goggles

My Feedback: (4)

Thanks for all your help guy's!!!

I tried re-wording the poll as suggested but only the moderator can.

More information,

I was thinking about using 6 Hitec 5645's (2 on each wing, 1 on each elevator half), a 805 on the rudder and 425 on the throttle.

At this moment I'm leaning towards the single PPM receiver and dual Duralite batteries and switches.

Till now the largest I've had was a 1/4 scale Extra and if I'm distributing the Edge up here I better know how it flies.

Let me know if you need more info.
Thanks again.

Diablo-RCU

My Feedback: (1)

Rather than spend big money on fancy new battery technology, I'd buy one top of the line pcm receiver from the radio company of your choice and use that in your plane. Test fly the receiver in a "beater" airplane first to make sure it is reliable and range checks very well in the air. Get the plane really high and collapse your antennae...still in control...super. Extend the antennae. For the 35% plane, I'd use one receiver, 2 5-cell NiMH packs into 2 JR switches into the receiver. The 5-cell packs will keep the receiver from going into a low voltage failsafe on the high current drawing maneuvers (snaprolls).

rc bugman

My Feedback: (30)

I have a number of research planes (ca. 22 planes) and they all fly on dual rx with op isolators. I have saved a number of planes due to failure of one radio system (battery, switch, connector, rx). There is too much invested in larger planes and the safety issue becomes more important, the larger planes get. The cost of the second rx is minimal compared to the investment in the airplane.

Elson