40% power setup
 

Ok guys so I think I got bit by the bug to go bigger. Just want some honest opinions about power setups for a 40%.
I know I could just go the usual two 4400 4 cell packs with regs. Or I could go that cool powerbox setup. Please let me know what everyone is using. Weight is an issue too!

For engine I am leaning toward the trusty DA 150.

RE: 40% power setup
 

There have been many threads on this so I will be breif as I am sure there are going to be lots of long replies here.


My setup and some reasons why.

2 4000 MAH Lipos, Lipos will deliver more current thus less voltage fluxuation under load.

2 Fromeco adjustable regs set to 6.5V, These are built very well and have a huge heatsink very easy to adjust.

1 Smart Fly Batt Share, This will balance the batteries and keeps one regulator from becoming the domiat power conduit. My batteries are never more than .01V different after 6 flights.

1 Smart Fly Power Expander. Provides a robust power buss, allows me to set regs to 6.5V that the servos get but still regulates RX power to 5V. Filters the power to RX so if the servo leads pick up any RF it dosen't get to the RX.

1 RX, Actual receiver failure is very rare. There are a great many things that are put into the catagory of RX failure. Crystal popping out, using the RX as a 20 amp buss, not properly mounting, no service loops on wires. Stuff that can be prevented thus is not the root cause of a RX going south.

2 JR charge switches, I have been using these on every gian scale airplane with zero failures, They handle the power day in and day out.


There are going to be lots of guys saying that my setup is too complex, has a single point of failure ( RX )and adds unnessesary weigh. Well.........bottom line is that it works and works well. Can't argue with success.


Shawn

RE: 40% power setup
 

This is the only component in this setup that I do not agree with. It introduces a single point of failure, and what's the point? Why is it desirable for both batteries to discharge at the same rate.

When you simply plug in 2 regulators without the battery sharing gizmo one will discharge faster than the other, but in high current draw situations they both supply current. Each serves as a backup to the other with no sharing device required.

TF

RE: 40% power setup
 

I agree with Tom. I went from two receivers in a 40% Katana to one receiver and a power panel. That plane went in last year and I believe that having a single point of failure gave me no chance to save the plane. I know some other guys that have been using one receiver and a power panel with no problems.....yet.

RE: 40% power setup
 

Tom, the Batt Share actually is not a single point of failure. It is basically a PCB with a couple of diodes and to fail both diodes will have to fail at the same time, not very likley. The reason why I don't like the batteries run down differently is that I know when I hook them up to the charger they are going to take roughly the same amount of time to charge. If one takes significantly more time than the other than I Know I have an issue that needs to be looked at. In a unregulated system if one battery is discharging faster than another then upon power up the higher voltage battery will try to charge the lower thus spent capacity. There are literly a hundred way of setting these up, most work well.

Vince, what was the actual cause of the crash? If it was an interference issue then 2 receivers would have have offered no benifit. Remember a power box seperates servo and RX power so the RX see's a much cleaner DC voltage and reduces the chances of interference that may be generated within the airplane. In any event I'm sorry to hear you lost an airplane.

Shawn

RE: 40% power setup
 

The cause of the crash remains undetermined. Both elevator halves would only work from 50% down to 100% down. Every other flight control worked normally. Post-crash everything worked fine. The power panel was one with servo programming. I think it comes down to the receiver or panel.

RE: 40% power setup
 

I guess I can just go with what I know for now. This wont be a test bed for the new synth JR rx although I have been using the synth 9303 just fine. Ok now just have to talk to Tom sometime and get the plane on down to South FL.

RE: 40% power setup
 

So at center stick you still had 50% down elevator but had control from 50% to 100%? If thats the case I would have to think that the Power box with the servo syncs may have been the culprit. Thats another reason why I went with the Smart Fly is that the Equalizers/Matchboxes are seperate items. I keep a spare in the box just in case I need it. I don't really like the ones with everything built in just for this reason but you can see my point that it gets really easy to blame the RX when there is no obvious cause.


Shawn

RE: 40% power setup
 

I think I might be nuts and go with two servos for the ailerons and just one for each half of the elevator. I might wait for some feedback on that setup before I do go through with it. Im thinking either 5955 or 8611A's.

There will always be some failure point in any system. It seems with a dual setup on everything except the RX it should be fairly safe. This is why I opted to move to a 40% instead of getting another 33-35%. The cost really is not a whole lot more over a nicely setup 35%. I mean in most of the setup things are just so similar to how I have my 33% setup now anyway.

RE: 40% power setup
 

As long as the servo driving the elevator half has ample torque to drive the surface, and the control point is somewhere near the flight surface center, a single servo will work absolutely fine. People have no idea of how much extra torque we are using with servos on our planes that we will never have need for. I see mini servos used on the flight surfaces of 40 plus pound planes all the time, and as long as they are set up right they work fine.

I don't for a minute suggest that we use them on our 3D planes, but it was provided to illustrate a point. Metal gears, torque, excellent linkage and geometry, and a good power supply take precidence over servo quantity in most cases.

Pat

RE: 40% power setup
 

8611A's Should get R done. I usually get a good idea on how well the servos will do the job during flying. Doing some hard walls is a good indication. Also really fast rolling harriers seems to be a give away. I think so long as they are stab mounted or I modify them to be there I should be fine.

RE: 40% power setup
 

Shaun,
I have did a lot of research on this subject. Power only flows one way through the fromeco regulator. the ground is common. It is impossible for one battery to charge the other. On my 33% I plan on using a power expander like yours I love the way it has two deans connectors in parall so you can plug to seperate battery circuits into it with deans connectors and 18 guage wire. On my 28% i use two batteries two switches and two regulators pluged into seperate chanels in the receiver. 230 flights no problems, one battery does discharge a little faster than the other, but even after 10 flights it takes less than 2 hours for both to charge full. I do swap my bateries around every 50 or 60 flightss so they see the same cycle times. The batt share may have electronic redundancy but both chanels share the same control circuitry and the same output wire, even a wire can be a single point failure. Not trying to start an apples and oranges discussion just giving my 0.02.

Also I have a power expander for my 33%, How does your servos perform on 6.5v? I have never heard of anyone regulating them above 6.0v

RE: 40% power setup
 

Dntmn, if you go back and read my post it will state that the high battery will try to charge the low battery on an unregulated system. I really like to have fast moving surfaces and at first I was acheiving this by running a 1:1 servo arm/control horn ratio. I was having some difficulties with my ailerons blowing back on snaps so I changed to 1:1.25 ratio and bumped up the voltage to get more power at the control horn. Been flying it like that for a couple of weeks now with much better response. I was shocked when I let an Unlimited pilot fly the airplane and was told my ailerons were getting blowback with 2 8611a . Then again the ailerons on this airplane are a tad over 200 Sq.


Shawn

RE: 40% power setup
 

I have heard that JR's can be handle up to 8v on their servos. Not sure if this is true and if there is any added performance or not. I know Hitec's get a little jittery at anything above 6.5v.

RE: 40% power setup
 

Shaun you are correct! didn's notice the unregulated part. I am using a power expander with hitec digitals on my 33% what voltage would rou recomend running the servos at?

RE: 40% power setup
 

I would stay at 6V. The only reason I went to a higher voltage is an attempt to squeeze every last bit of performance out of the airplane. In a couple of weeks I may find that there really was no benifit to running 6.5V and all I did was increase the wear of the geartrain. Being that I compete in at least 6 contests a year I will try different setups and flying styles during the winter to see just works the best with the upcoming seasons sequence. By the first contest of the year I am usually pretty comfortable with my setup and tend to leave things alone and fly as consitantly as I can. This years sequence however has some oddities to it that is making the ideal setup difficult to get. So far the best I can do is to be clicking to different rates throughout the sequence.


Shawn

RE: 40% power setup
 

Shawn What class you flying?

I am still in basic and have flown in 3 contests and CD'd 5 contests. 230 practice flights later I am ready to move to sportsman, but Have not goten in to a comfort zone on the first sportsman maneuver, I just can't get my thumbs and plane to coperate on the 1 positive snap on 45deg downline...Practice Practice...

RE: 40% power setup
 

Ill admit that the parts of sportsman were a challenge. To be honest I fly mainly 3D and freestyle. I think rolling harrier figure 8's are easier then some of the IMAC sequences. I actually found a group of other 3D flyers that just started flying IMAC.

I am on the list now for the new 40%. I will be purchasing all the other things to make it work in the meantime. Chip Hyde has a nifty CF spinner that has a single bolt through the front instead of all the little screws around the base as with my other spinners.

I like the fact that the wings are built up on Tom's plane. Should make for some really lightweight wings.

So for now I am off to purchase a whole bunch of 8611a's and I might also use some 5955's as well. I will probably go with a Fromeco lion setup this time instead of the usual TBM batteries I use.

RE: 40% power setup
 

Dntmn, this will be my 3rd year in advanced. Lots of guys have issues with snaps usually because they like to run too much rudder and elevator. For sequence flying I like my throws close to the following.

Elevator Up 18 degrees down 20 degrees with expo at 45

Rudder 20 degrees both directions with expo at 50

aileron 30 degrees with expo set at 60

Right now I have these setting on my low rate but the the first 4 manuvers are flown on a higher rate because they require more rudder. Lots of guys that do 3D and then start flying sequences have too much throw and not enough expo because they are used to flying with lots of throw. To jump directly to my throws would give the feeling of limited control. Remember, if the judge can see the correction he will deduct points for the mistake and the correction. Makes it really easy to see 4s and 5s on the score sheet.


Shawn

RE: 40% power setup
 

I didnt think that cross-charging was possible?

RE: 40% power setup
 

Check out Reds battery clinic and Nobs faq for cross charging info

RE: 40% power setup
 

Josey,

Think about it for a second. It's kinda like a dam in a river. Without the dam the water will always flow down hill, but having a dam is like having a regulator in preventing the free flow to the lower side of the river. Add to that the comparison to when you use a fresh battery to jump a low battery to start a car.

Since you can plug a battery into any unused port of a receiver bus and power the servos from either end, it becomes clear that a receiver has no directional voltage restrictions at the bus ports.

RE: 40% power setup
 

I save the 3D for foamys and profile planes. My gas planes are used 98% for precision. My elevator and rudder is about where yours is I goto high rate rudder for hammers. I think a lot of my problem is that My ailerons are too low(15 deg)..I made a high rate aileron for the snap 35deg but i think it was too much i just dropped it to around 25 deg and will try than next time i fly. My snaps look good straight and level. manuever one in the sportsman sequence it 1/2 cuban 8 1/2 roll on entry push to 5/8 inside loop 1 positive snap on the 45 degree downline. I think i have three problems. #1. I am droping to idle on the down line i think i need 1/4 throttle to keep more momentum(my snaps is sometimes teally big). #2 I think my aileron rates ar a little too low #3 The idea of burying the sticks on a downline is scary.My but puckers 1/2 second before my thumbs bury the sticks.

RE: 40% power setup
 

I read the NoBs FAQ and they said it took 24 hours to have one battery charge the other battery and in the process lost 20% capacity. That's over 24 hours. So what would you lose over an hour or two? 2% capacity? Not sure the diodes etc are really necessary.

RE: 40% power setup
 

Sounds good to me! I knew it wasnt an issue with nicads/nimh's but wasnt sure about lithiums