My First Giant Scale Gasser

[Scotte 540]

I am putting together my first gas plane and I'm looking for advise on the guts-----this is what I have so far----PAU 36% Edge 540
Rudder--JR 8711 (1)
All other surfaces--Futaba 9156's (6)
Throttle--Futaba 9351
Duralite HD battery system--(2) 3000 Mah lithium manganese for receiver (1) 4300 lith ion ignition, 3 hd switches & (2) 6.0v regs.--HD deans plugs & wiring
Smart Fly Ign. cutoff
(2) Jr matchboxes
---I'll be using a Futaba 10c & 14 channel 2.4 Fasst
Question: Should I be using a power expander with this setup? If so why and which one?

Just a weee bit more complexed than my glow stuff!!

[rrritchey]

Hi,
Its really up to you but I feel you would get better response from your servos if you did use a PowerExpander or PowerSystem. One issue you have here is that two regulators can never be matched perfectly so you are drawing the majority of your power through one regulator. This causes more stress on that regulator because it will be hotter than the other most of the time. You also are probably going to see uneven battery draw, it might be slight (10%) or it could be sever (75%). The other issue is that you are loosing a lot of voltage through your Matchboxes when your servos want a lot of current. Your servos hanging off your Matchboxes might be seeing only 4.5V-5.0V when they want a couple amps of current during maneuvers where there is a lot of force on them . The advantage of a PowerSystem with built in servo matching is that each servo can have its own lead and this greatly increases voltage the servos see when drawing high current. On a PowerSystem you also get the regulator tied directly to the servo outputs, in your system you are going into the receiver bus through standard R/C connectors and dropping voltage across them at higher current loads before you even get to your receiver bus. This is all personal preference but I would not sell PowerExpanders and PowerSystems if I felt they did not add something to the performance of planes this size.

[Scotte 540]

So with a power expander I could still use the Duralite regs. & JR matchboxes and the current going to the matchbox/servos and the battery drain is better regulated? I'm trying to come up with the best setup without having to return or sell some of the stuff just purchased and without spending lots more mula----safety and the longevity of my equipment is more important to me than trying to save a few dollars as well.....

[rrritchey]

Hi,
Honestly, I would recommend dumping the Duralite regulators and the Matchboxes and going with a PowerSystem Eq6 but I understand your point. Keeping the Matchboxes will degrade your servo response, no two ways about it. Keeping your Duralite regulators will cause mismatched battery draw. If you want to keep your Matchboxes you could go with a PowerExpander Pro, if you want to get the best servo performance then go with a PowerExpander Eq10. Let me know if you have any other questions.

[smokin]

i'm with bob on this one.. the EQ6 has all you need right in one package! since you already have the ign kill you don't need the highest version. this will match all of your servos, regulate your batt power to servos and rx and will provide better servo response! you can't go wrong!

[Scotte 540]

Another option I thought about, would be to keep my regs. & use Smartflys Battery share Ultra module----ditch the matchboxes and use the full potential of my Futaba 10c......I should be able to run 4 aileron servos (match them with the radio) and 2 elevator servos, rudder, throttle and have a channel for the ign. kill and 1 channel left over......I think this radio is capable of doing this...any thoughts on this setup?

[rrritchey]

Hi,
Basically the problem with any gas plane 50cc and larger is that the way to get the power onto the receiver bus is a problem. Using the BatShareUltra won't help you here since you eventually have to go through a standard R/C connector to get onto the receiver bus. This is where you will loose a volt or more at high current loads (6-8 amps). If your regulators are set to 6.0V then you will have about 5.0V on your receiver bus or less. If a servo wants 2amps its going to end up getting about 4.5V or less, check out the torque the servo produces on that voltage vs closer to 6.0V. Its really up to you and how much performance you want out of your servos and therefore your plane. Using a power system from anyone will make your snaps cleaner along with other maneuvers that require a number of servos to draw significant current. Cleaner snaps make for better scores in competition. You did not say if you wanted to fly competition so maybe this is a null point. Any wiring hooking will work, nothing will fail, its just a matter of performance.