RustyTumbles

I would like to keep the two RX battery setup, just for a back up if one battery or switch fails I know I have a back power supply so It won't just go screaming into the dirt!!

What kind of flight time can I expect with the two 800mah packs? Or should I use 1100mah packs?

The way it will be set up is like this.. Each battery will plug will plug into a seperate switch and the on the other side of the switch harnesses where you would normally plug into the receiver the Y lead will join the two power lead into one, then this plugs into the receiver battery slot.

Is this the correct way to do it?

Stick Jammer

That will work but don't use the "Y" connector if you have another open slot in the Rx. The "Y" is just anther possible link to fail. Just plug each one separately into any open slot in the Rx.

Nogyro

My Feedback: (10)

If you're running 4.8 volts, your two 800 will be plenty. I used two 700's on a Giant Stinger with Hitec 645mg's all around, and I would get 7-15 minute flights out of them.

ptgarcia

My Feedback: (36)

As Stick Jammer said don't use the wye, just plug the 2nd battery into any open slot on the receiver. And I would go with something a little bigger than 800 mAh, the 1100 mAh packs sound like a better choice.

RustyTumbles

How much more time would I get on the 1100mAh batteries? Keep in mind I'm not going to be doing 3d, just some basic IMAC and a few tumbles and snaps here and there... I already have one 800mAh battery new in the packet. So it's one less I need to buy. Don't get me wrong here I don't want to skimp on safety critical items, but if two 800mah are enough why spend more something that is not needed!!

Nogyro

My Feedback: (10)

Do you have a battery cycler to where you can cycle the battery and tell how many milliamps are taken out of it? If so, cycle the battery, find the capacity of it when fully charged. Go fly the plane for 2-15 minute flights. Go home and cycle battery and see how many milliamps you draw out of it. That will tell you what kind of amperage you are drawing per flight. You'll want to leave yourself a cushion. Do you normally fly 4 flights when you go to the field, or do you do 8 of them? Big difference. If you are doing mostly IMAC, I think you'll find two 800's will be enough. I do this with all my planes. It's really the only way to find out how much current your servos are drawing for your type of flying.

RustyTumbles

Unfortunately I don't have a cycle to do that! When I fly I normally have between 4-6 flights 10-15min each, depends on how many of my students are at the field. (I'm an instructor too).

what about checking battery voltage before each flight? Will that tell me if my batteries are getting low?

The servos in the aircraft are as follows:
ailerons- Futaba S9203 in each wing panel
elevators- Futaba S9151 on each half
throttle- Futaba S3001
rudder- Premium S605 FET (22kg torque)

Does this help?

ptgarcia

My Feedback: (36)

You should get somewhere around 30% more flying time from the 1100 mAh packs. If it were me, I would feel really uncomfortable putting 6 15 min. flights on 2 800 mAh packs. I'll tell you what, my feelings are based on my plane with 5 high torque digital servos and a standard digital. I'm not familiar with your servos, so take that into account. Good luck!

Nogyro

My Feedback: (10)

Big difference between 10 and 15 minute flights. My Futaba 8UAFS has a timer in it, so I always fly 15 min. Much easier to keep track of actual time on batteries that way. Some guys use a cooking timer attached to the transmitter if they don't have a built in one. You really need to be pretty close on your "air time" in order to get a feel for how long your batteries will last.

Yes, that will tell you, but might I suggest you take your reading as soon as you land. That way you will have a more accurate reading. If you wait 45 minutes before your next flight, and then check your batteries, they will rebound while sitting there and your reading won't be as accurate. I wouldn't fly much below 4.8 volts without using a cycler to know exactly what your battery capacity is. You should get in the habit of checking your batteries with your ESV meter after every flight anyways.

Here is the cycler I use. Very simple and accurate. http://www.chiefaircraft.com/cgi-bin...html#SuperTest It's the Super Test. As you get into these bigger planes with more $ invested, you have to keep an eye on your batteries. A cycler is a must in my book.

Your servos look plenty strong enough. I couldn't find a chart anywhere that showed what kind of current they drew though. Like I said earlier, I flew my Giant Stinger with 2-700 mAh 4.8 volt nicads for three years, no problems. I'm flying a Wild Hare 28% Edge and Extra now, and since I went to 6 volts, I increased my batteries to 2-1100 mAh 6 volt nicads. I'm running 5- Hitec 5945 digitals, and one std. servo. I'm able to get 7-15 min. flights, and still have a cushion. That's enough stick time for me in one day.

My advice is get a battery cycler of some kind, cycle your battery to make SURE it has the capacity it's listed at. Go fly you plane for a flight or two, cycle battery, and see where you're at. Hope some of this helps.

RustyTumbles

I also have a spare 6v 1100mAh battery new in the packet! If I was to use 2 of those would I need to fit regulators? Whats the main differance between 4.8V and 6V other than voltage and increased servo speed? Is it worth using 6V the the WM extra or should I just go with 4.8V?

I'm going to have a look around here in the LHS for a battery cycler, sounds like a really good investment!! Thanks for pointing it out!!

Stick Jammer

You also get more torque from the servos in addition to speed. Check with Futaba to be sure your particular servos are OK with unregulated 5-cell packs but they should be fine. Although 5-cell packs might not be the way to go when you're trying to save weight.

RustyTumbles

yeah I might just bite the bullet and go for the 1100mAh 4.8v packs! That way I'll know I've got a bit of a cushion...

Any idea how long the G38 will run on a 24Oz tank? I replaced the 14Oz tank that was previously in the plane with the 24Oz and now I'm thinking it may be to much. What do you guys think?

ptgarcia

My Feedback: (36)

I get 15 min. flights with my 20 oz. tank and Brison 3.2 on my Laser 200.

Nogyro

My Feedback: (10)

bigsport,

Check out Servo City http://www.servocity.com/index.html and track down your 9151's. I believe they said 4.8 volts only. A 16 to 20 oz tank is plenty. I ran a 16 oz on my G38. I'm using a 20 oz for my DA-50, and rarely use more than 11 oz. in a 15 minute flight.

RustyTumbles

I just brought 2x JR 1100mAh 4.8v packs! Saved 3Oz over what was already fitted.. So should I just run the 14Oz tank instead of the 24Oz?

RustyTumbles

You are right it does say 4.8v only!!! Thanks

Nogyro

My Feedback: (10)

No use in hauling an extra 12 oz. of fuel around. Try the 14 oz for a 10 or 12 minute flight and see how much fuel you have when you land. I always count my pumps on my Dubro gas filler.

RustyTumbles

Ok the 14Oz tank is back in and the batteries fitted also.. I put the wings on to do a trial CofG check. What is te best way to balance these big planes? I'm affraid that if I flip it upside down and try and balance it in my fingers I'll either drop it of my fingers will go through the wing skin.

Could anyone tell me where the CofG is on this plane?

Nogyro

My Feedback: (10)

Can't help you out on the CG placement, but when you balance these bigger planes, it really helps to have two people. If you happen to know someone with the Great Planes Balancer, it will work on a plane that size. If you get a cg measurement of so many inches back from the leading edge of the wing tip, two people can just lift it up at the wing tips to check it.

RustyTumbles

I did find a measurement but it is at the wing root at the fuselage. (165mm from leading edge)
Is there any way to convert this to the wing tip?

Nogyro

My Feedback: (10)

If the leading edge was straight like on an Edge, then there wouldn't be a problem. You may try putting a mark on your wing on both sides of the fuse, then running a string or using a straight edge directly over them out to the tips. You really shoud be able to check the balance by yourself. I did on my 17 lb WH Extra. I just used my fingers. Not exact, but close enough. Just use plenty of expo on your elevator for the first flight just in case you're a tad tail heavy.

RustyTumbles

Yeah I did manage to balance it in my fingers, I just needed someone to tell me where the mark was on the fuse side. (couldn't see both by myself) It sill needs a little nose weight, but I haven't got the new muffler or receiver fitted yet. So with the new muffler and reciever fitted up front It should balance ok!! That was also with the old wooden zinger prop fitted as well. I plan on running an APC 18x8 to start with, will the APC be heavier than the zinger or lighter?

Will a hitec eclipse 7 channel QPCM talk to the futaba servos? I need to upgrade my Tx and the eclipse was the one I was looking at...

Also how far away from the engine does my receiver need to be

Nogyro

My Feedback: (10)

bigsport,

The APC will be heavier.

It should work just fine. Normally the servos work no matter what type or brand of receiver they are plugged into.

The rule of thumb is 12". Just be sure to do a range check with motor off, and then with it running. You shouldn't lose more than 20% distance. You should get 100' or so with 1 section of the antenna pulled out, but this a whole subject in itself. Lots of different opinions on this one.

RustyTumbles

Thanks... I'll go with the 12" rule and see how it goes. Have a merry christmas!

RustyTumbles

Do you think the Hitec eclipse QPCM is a good choice for a TX or should I go for something better? I don't think I'll ever use more than seven channels...

Also is the swallow digital charger/discharger a good piece of kit for cycling batteries?