I have a set of 4 Futaba S3003's and a set of 4 Futaba S148's. I looked them up on the Futaba website, and the specs are quite different, so I'm not sure which ones to use.

@4.8v:

S148:

Speed: 0.28s/60 deg
Torque: 33 oz-in
Weight: 1.6 oz

S3003:

Speed: 0.23s/60 deg
Torque: 44 oz-in
Weight: 1.3 oz

Do I want the speed or the torque? I'm using them in a 60" wingspan trainer, so do I really need speed? The website also calls the 148's "S148 Precision" so does that mean they are really more precise?

Looks like what you have posted that the 3003 is faster but also has more torque. So when you asked, do I want more speed or torque. With the 3003 you get the best of both worlds.

You'd have to dig around in the Futaba support forum http://www.rcuniverse.com/forum/forumid_125/tt.htm to find it but there was a reply a year or two ago by Krysta (Futaba rep) that describes why the S148 and S3001 are considered "precision" servos. There was also mention that they handle vibration slightly better than the S3003 and S3004 so they are recommended for helis and the S3004/S3004 are not.

Either servo is plenty for your trainer. S148 currently sells for $13.99 and S3003 is $10.99. I'd put the cheaper servos in the trainer.

Oops, I'm kinda out of it today and for some reason I thought a bigger number was better. I should probably eat a better breakfast or something...

Also: Should I go with a 4.8v battery pack or a 6.0v? I can do either one because I have to cut cells out of my custom pack either way. It's a 2650mAh (I know it's overkill) 7.2v pack right now (I had a Radioshack Pro-Pulse car and refused to pay $25 for some crappy Ni-Cad's), so I can either cut 1 or 2 cells out.

With that current rating, you could go either way. The six volt pack will give you both more speed and more torque for both servos.

If you wanted to mix them up, you could always use the higher torque for aileron, elevator, and rudder with the lower torque for the throttle. That is if you are using one servo for the ailerons. If you are using two, well, for a trainer you can go with the lower torque, one on each side, higher torques for the rudder and elevator.

If you go with 4.8 volts, you can do pretty much the same thing but with the lower torque (as noted) and speed (also as noted).

Either way, you are fine.

That is a big battery pack. Yeah, overkill considering the standard pack that comes with most 72 MHz radios is 4.8 volts at 600 mah.


CGr.

There's no downside to having the 6 volt pack, so go ahead if you've got the charger to take care of it.

Since I've heard you can get 2 or 3 flights from a 600mAh pack, I could probably go through a gallon of glow fuel before I would have to recharge my pack! I also have the same custom pack in my radio at 9.6v as well.

The packs do self discharge though, and the voltage gets marginal around halfway. You still need to have a fully charged pack when you get to the field every time, even if you didn't use it all up the last time.

First, use either - in a trainer, it won't make any difference.

Second, you go through a gallon a fuel in 3 flights?????

He's got a 2650mAh pack, so I think he's figuring 2650/600 x 3 = 13 flights on his battery and about a gallon of glow fuel.

Precisely. And I was sort of kidding about the gallon thing, but still, it's one big pack.

on a spad trainer w/ a gms .47 i have gone through 2/3 of a gallon (at half throttle most of the time) before i drained my batterys to the limit (they were starting to slow down when you wiggled all of them, yes i know i shouldnt have done that, i was a noob at the time)

point is you really dont need more than 800 nicd in simple 4 servo models. i prefer 1400-1600mah 6v batteys but you really dont need them

also towers prices on batterys are insane. look here
http://www.all-battery.com/6vnimhbatterypackseries.aspx 6v batterys
and
http://www.all-battery.com/48vnimhba...ackseries.aspx 4.8 v batterys

For a trainer, and most of my planes, stong, simple analog servos rule.

I also put 2,000 mA NiMH in all my 40 sized planes. I do check the voltwatch on each plane before each flight, but having a strong battery takes one more concern away, so it's easier to have a low stress flying day.

Jack

The prices are really low at the website linked about, but I wonder what cells they are using. Different brands are not created equal, and cheap cells have a higher failure rate.

I build my packs out of Duracell cells. I get em at Safeway for $10/4 batteries! I've bought like 4 packs already...

Duracell cells, are they rechargeable NiCD or NiMH ?
you can fly on non rechargeable batteries i just dont see the point of it, what to dig it out of the airplane every time?

in my 4-5 servo S3003 airplanes i'm using 1000 mah and 1500 mah battery packs, if i buy new battery packs let it be more mah.
i'm getting 6-8 flights from these packs.

the down side of this is the long charge time of the 1500 mah about 45 minutes.
with the 1000 mah its something like 15-20 minutes charging.

im charging it with a Hobbico QuickPeak charger on my way to the field and one more time during day, for the Tx and Rx.

Alex

You should get 5 or 6 flights on a 4 cell 600 mAh pack with standard type servos in a trainer.

5 cell packs do give much better speed and torque, but be aware that some charging systems may not charge them and the discharge rate is higher than a 4 cell packs. The same warning about charging applies to using very large capacity batteries.

Yeah, and for a given pack size.. both being the same mah rating (not that they are, but if they were), the 6 volt (5 cell pack) would not last as long as the 4.8 volt pack. You have to make a judgement as to what you want... speed and torque... and make adjustments in the size pack. The trade off here is torque using a 6 volt pack, which will eat more wattage (meaning more current x voltage) than a 4.8 volt pack so if you do go to 6 volts, you have to increase the amp-hour rating (mil-amp rating) of your pack.

The OP said the pack size was, what.. 2650 mah? Heck, that will last for a good number of flighgts no matter if it's 4.8 or 6 volts.

CGr.

Since we're chatting about batteries and the like I have a couple of questions for those that know..... First, if i'm currently running a 4.8 volt pack and my HANGAR 9 ESV says red at 4.5-4.6 volts does that mean that if I run a 6 volt pack that it would be in the red at 5.7-5.8 volts or would it operate normally down to that 4.6 range as well? Secondly, if I do go to a 6 volt pack is that voltage fine for running the whole receiver or do I need to use a regulator somewhere in the system? Just wondering.

Thanks

Ryan

I'm confused. 2650 mAh radio shack pack is custom? Are those sub C cells? If they are thats alot of extra added weight.

Duracells from safeway? Which is it?

Goldberg Tiger 60
5-3004 futaba servos
600 mah receiver batteries
12 oz tank
90 fx

I get 6-7 flights easily at 10-12 minutes each flight on one charge. When I'm done I turn my radio and receiver on to run my batteries down and it still works the controls for another hour or so.

Once they are drained I recharge them back up for 18 hours using the 50/50 mA wall wart charger my radio came with.

600 mah batteries divided by 50 mA charge rate = 12 hours X (1.4) = 16.8 hours for a full charge then I add an extra 1.2 hours charge at the 50 mA rate = my 18 hour charge.

If you want longer performance out of your batteries use a slow charger (wall wart) rather than those fast chargers. The fast chargers will also decrease the life of your batteries compared to a wall wart slow charger.

If you only make only 2 or 3 flights and are afraid to fly any more, make your 2 or 3 flights, turn your receiver and transmitter on, play with the controls, and you'll be surprised at how much longer your controls will still work!

Your 6 volt (5 cell) ESV is warning you to stop flying at that 5.7 - 5.8 red line!

I said I refused to buy RadioShack's expensive, crappy packs, so I built my own using Duracell 2650mAh AA's. Hope that clears everything up. They are just what I had at the time, an they aren't heavier than NiCds, plus the cells are cheap so I buy more if my fast charger kills 'em.