Still Confused about No of Rx and use of powerbox set-up

[dblades]

I have been flying 33% and smaller planes and now have a 40%.


I have a 40% TOC YAK and will be installing 10 JR 8611A servos on Ailerons and Elevators, Seiko PS-050 on Rudder and a couple Futaba servos for throttle and choke. I plan to use 1 or 2 Futaba R149DP Rx. Also will be using FROMECO Li-Ion with FROMECO or MPI Regulators. While not necessarily constrained by $$$ I do not want to particularly spend hundreds of $$$ on something I do not need.

I have searched and read a lot regarding how many Rx to use and the use of powerbox systems like the Smart-Fly Power Expander. I am feeling the “Old School” recommends going with 2 Rx for 40%. ???

Using 2 batteries per Rx is a given as every opinion seems to point to the battery as the weak part of the system. Exception to this is where 2 Rx are used with only 1 battery per Rx – I find this confusing and a contradiction??

I somewhat understand using the Power Expander for primarily reducing RF noise and flowing power to servos as each servo can be plugged into the Expander, BUT, I will be using JR MatchBoxes (up to 3 servos) which will actually connect to Rx or Expander using one extension. What benefit would the Expander provide??

Will one (1) Futaba R149DP Rx powered by 2 batteries (w/o use of powerbox) not handle the all the servo requirements ??

[notorious_benny]

Hi there dblades.

You will get a whole myriad of different opinoins on radio set up.

I will throw my opinion in there, but you can be assured that someone will disagree with my thinking, as it really is personal preference.
Your right, one battery per reciever is a bit of a waste of time, you lose just one batt and you also lose the rx.
In my Yak, I used to do it the simple way. 2 batts, 2 switches into one rx without any powerbox style devices. I was running 8 JR 8511's without any problems at all.
When I shifted to li-ions I went with a powerbox, as in the brand name powerbox. I like this thing as it regulates my voltage, and if I lose a battery the bad one wont drain the good one.
Also it has an 'electronic' switch not a mechanical one which almost completely eliminates that failure point.
But the best thing about a power box is that it provides power to the reciever/s via all the servo inputs(There is no need for a separate 'power' lead), on mine there are 5 inputs to the rx. What this means is if you wanted to run 2 receivers you could run them through the one powerbox. Taking away the failure point of only one battery. As with this setup if one battery dies then both recievers will still work.

I personally dont see the need for two receivers, but that is only my personal preference, If you feel better using two receivers then go for it, lots of people use two succesfully. My reciever ran 8 servo's fine, but I am setting up a superxtra and will be using a powerbox to take the load of all those servos.

PS, if you use a servo matching powerbox you dont need matchbox's, and if you use hitec servos you don need a servo matching powerbox or matchbox's.

[sweetpea]

Ditto.......

Most folks run the powerbox to ensure each servo gets its 6volts as the RX doesn't do as good a job on that. With longer leads and more servos, holding power needs volts!

As for dual RX's.......I won't ever do it, but many do without problems.

[jack01]

The way my Extra is setup is just two batteries, two older Powerflite adjustable regulators, two switches, and one reciever.

- The Powerflite regulators are adjustable, so I have them set to deliver 6.0 volts under a 1 amp load on my longest extension

- If one battery dies, then the other will fly the plane untill it's on the ground. I'll just pick up on it when I check the voltages before the next flight.

- Realistically, you're not going to burn up your reciever in a 40% airplane. That's assuming you're not building a 40% A380. A modern JR or Futaba reciever can take 50-60 amps before it melts. Horizon has told me 60, I have heard as low as 40.

[excelpoint]

On My 44% Comp Arf Giles I use two Futaba G3 Rx's with the plane split down the middle, one Batt on each RX. Theoretically if I lose one RX I will still have half a plane to try and get it down or at least a controlled crash away from people etc. I have 5 servos(JR8611's and Hitech 5955TGs) on each RX and have not had any power distribution probs. On my next 40% plane i will be doing the same thing.

[rcdart]

Opinionated bunch arn't we,and nobody is wrong, just have different thought process, LOL. Using 2 RX with a powerbox is a great idea I believe, both batteries power both rx's so all is good, still have power to both rx if one battery goes out to lunch.
In my 40% 260 I have gone one step further, 2 rx, 2 powerboxes, and 4 batteries, some think its overkill, not me I love it.

[SleepyC]

	Quote:
	Using 2 RX with a powerbox is a great idea I believe, both batteries power both rx's so all is good, still have power to both rx if one battery goes out to lunch.

This is the main point.
With a power box, your not connecting the batteries to the recievers... your hooking the two batteries into the power box... and it sends "clean" power to both receivers.
So if one battery goes out, the power box, will automatically shift to just use the remaining battery and you should be fine. Also, it gives each servo the proper amount of power so you will experience no fade.

I think if you were to use two 4800 lit ion packs.. you would have more than enough power for many many flights.

I use 1 4800 lit ion pack and a smart fly power expander, on my 35% and I can't fly enough in one day to have to charge.


And as others have stated.. everyone has their own way of doing things, pick through it and make your own decisions!

[Biff]

Aw, what the heck! Might as well chunk my opinion in as well. As Jack stated, ampacity is not an issue. 1 receiver can take the load of more servos than you could gang into with no trouble. My take is keep things as simple as you can. If you have a spankin' new Ferrari F-40 and a 1980 VW van and set off on a 50,000 mile trip around Europe, who would win?

I have been a 1 receiver guy for years. Let's face it, if you fly with two receivers and get hit on channel 40. BOTH receivers get hit. Other than having a chrystal fall out, I've never had a receiver fail. I tape all chrystals in and always protect all my electronics from vibration.


Another issue is range. Take a plane with two receivers and do a range test. Then take a receiver out and test again. You'll be surprised!


I used to use two switches on EVERYTHING including ignition. Then I realized I've never had a switch fail. I do use top shelf gear, I've never seen the reason to have a very expensive airplane and economize on extensions, servos, batteries etc. Not trying be a snob or to say that all this top shelf equipment in any way makes me fly better because it sure doesn't!! But honestly I just don't have airplane problems.

I would have to agree that the battery system is the weak link. What's the cause? The human factor plays a big roll, at least from my experience. The battery system is about the only thing on an airplane that requires fiddling with before you leave for the field every time. There are a thousand different chargers that might work for each battery. There are just as many testers. I see lots of models every year. In an effort to save weight and go for a clean looking install, most guys pretty much hard mount batteries with a bit of foam and wire straps. Oooph, BAD!


I was very involved in all sorts of testing. From thermal shock, salt fog accelerated wear, UV, blah blah blah. What I found most interesting was the vibration analysis. You can't believe how easy it is to break ANYTHING on a vibration table! The battery system is without question the heaviest single component (other than motor and tank) that gets mounted in a plane.

Not to give a dissertation on vibration (Sorry ladies!) but you remember "An object in motion",,,blah blah blee. Inertia is a bitch. Everything has a harmonic, in it's simplest terms a certain frequency that makes things look like Elvis on crack. Our airplanes have a constantly changing frequency due to our use of the throttle. Best thing to do is use PLENTY of soft foam, make mounts for things as short as possible, when using Velcro or wire ties on electronics DO NOT go super tight! That negates what the soft foam was there for.

Enough Inane prattle.

What my thoughts are boils down to this; We use redundant equipment to allow for failure. We also add to the possibility of failure by adding more components (what ain't there can't fail!) I say address the root issue of failure and attack it at the roots. If you have an electrical component on a shelf and turned it on and off 10 times on Saturday and Sunday, would you think it would ever fail?


Since I've really taken vibration isolation seriously, I simply don't have component failure. Actually I have lost one regulator in one of the Youth Masters airplanes. This goes over a period of 15 years. I've certainly worn stuff out, bit that's because of use!


If you plan on blasting through the Baja 1000 race at 100 mph, you certainly need all of the massive shocks, struts, tires, air cleaners, harness's neck protectors and a crew of 50 with spare parts enough to rebuild your truck. If you plan on a 1000 mile trip at 150MPH on a nice smooth highway, all you'll need is a couple of Cokes and some bitchin' tunes. The difference? Vibration.

Redneck deep thoughts.

Redundant equipment is used in case of failure. Failure is mostly due to vibration. Reduce vibration, reduce failure. Reduce failure, reduce need for complexity. Reduce complexity, reduce possibility of failure.Reduce possibility of failure, drink more beer with buddies. Drink more beer with budies, be happy.

Beer= good.

[SleepyC]

NICE!

I love when Biff gets deep... he makes the complex, easy to read!
Biff.. your like the Cliff notes to hitec RC!!

[Hoss]

Great post there Biff, I think you are right on the money.

The interesting thing I never thought of was from Jack's post about setting regulators to 6 volts off the longest lead.

[Biff]

Thanks dudes! Another thing I should really throw in is I've used Futaba and JR in the Youth Masters planes. The reliability on both systems is 100%. We've never had a glitch. One thing that's interesting is when I was setting up the YM planes, I was advised to use only one receiver. So if companies who are in the business of selling receivers advised me to use just one, there's something to think about.

One receiver with chrystal taped. two batteries and two switches. That's the set up I use on everything I fly up tp one hundred CC's.

Another REALLY important issue is using matched system. I've had airplanes with all one brand of extensions and 1- 6 inch extension of another brand (not Futaba or JR, won't give the name as that's dirty pool. Could have been a bad connector.) It drove me NUTS with radio problems. I replace the lead and problems went away. Cheap insurance; use Futaba equipment or JR equipment? Use their leads! I know there's plenty of off brand companies making fine gear, I just choose to use matched systems only. It's served me well!

[Dr. Yankem]

Biff...Your last post implies that you use a different set up for over 100ccs. What,for instance, do you use for your 150cc birds, and why do you feel that 1 receiver 2 switches and 2 batteries are not adequate for the larger engines.
I've gone both ways with my 40% planes, and use primarily the set up you posted, but I did have trouble with my Aeroworks Ultimate. 8 aileron servos with the necessary y connectors ended up with lots of power loss to servos causing blow back on the ailerons and rudder. It wasn't until I added a smart fly power box that I was able to solve the loss of power to the servos.