eepers

I've assembled a GWS ME109 (2 actually, but I won't go into that as weight conscious as possible, but it's still coming in at 15 ounces... about 1/2 an ounce heavier than reccomended in the manual, and at the very top end of what I've read online... I haven't even applied decals as I'm paranoid of tipping my chubby bird into unflyable territory.

I believe my GWS 8.4V/600 mAh battery to be my main weight area... Has anyone else built an ME109 (stock 300 motor) succesfully with another battery? What would you reccomend for weight savings?

Jason W M

My Feedback: (6)

On all my GWS warbirds and sport planes, Im flying Thunder Power LiPos. When I want as little weight as possible, I run the TP1320-2SJ packs. These packs weigh 1.9 ounces with 1320 mAh - your current 7 cell 600 mAh weighs close to 5.5 ounces!

The 1320 2 cell packs put out great power and give flight times on the average of 15-20 minutes on GWS planes per charge. If you want even more flight time, Id suggest the TP2100-2SJ pack. This pack weighs only 3 ounces - still nearly 1/2 what your current pack weighs and it has 2100 mAh! Flight times are 20-30 minutes per charge with ease.

LiPos are the biggest answer to saving weight, adding power and increasing flight times on electrics. BUT, you must have a LiPo capable charger AND be aware of the risks involved with using LiPos. They can be dangerous if not cared for properly.

You can get Thunder Power packs and a proper charger at most hobby shops who carry GWS airplanes, as well as many online vendors like:

http://www.esprtimodel.com
http://www.allerc.com
http://www.aeromicro.com
http://www.horizonhobby.com
http://www.thunderpower-batteries.com

Hope that helps!

eepers

Thanks!

I suppose something else I'm contending with is that the plane is pretty much balanced right now with the current battery... if I end up with a lighter battery, what's the best way to counter the CG moving rearward? I suppose it's all about battery placement, I haven't checked it but I suppose the battery compartment in the 109 is relatively centered... hmmm... have to look into that.

Also, does the stock motor have any problems with that much power?

eepers

Man, still lost here.

The world of power sources is making my head swim! Anyone got a good FAQ with layman interpretations of battery specs?

Can I use a 9.6V with my speed 300 motor or do I have to stay with the 8.4? Is the voltage what gives me the additional thrust or does an extra cell do that? Personally I'm not too concerned about my flight times right now, I just want some decent power without burning out my motor, and keeping as light as possible.

That and LiPos are pretty intimidating financially and safety-wise.

Any advice here? Is there some massive "readme" on power sources I've just missed somewhere along the way?

scott88-RCU

My Feedback: (1)

I have the GWS Zero and the Spitfire. Same dilema as you not enough power too much weight. First off try going to 9.6V you need the extra power and second go for a 400C motor it gives a lot more power even though it is a little heavier. Look at www.balsapr.com it has what you are looking for. I'm currently using a brushless set up and it's not the same plane I might add it's almost a pylon racer.

eepers

Excellent Scott, looks like a great place to grab one!

Looks like I'll grab an 8-cell Ni-MH 9.6V - 700mAh JST off there.

Currently I have a GWS ICS-100E 5 amp ESC, with that battery should I be running a ICS-300E speed controller? Are there any advantages to the larger controller?

Thanks again!

scott88-RCU

My Feedback: (1)

Yea you won't burn out the smaller controller. The thing is amperage and the 100 i beleive is 5 amps and you are probably going to run around 8 or 9 and so you need a higher amperage controller. There is a little more wieght but not much. Try experimenting with different gear ratios and fifferent props and see what gets you the most thrust. You can find a good scale to measure the thrust at a local bait and tacklefishing shop where I got mine. Good luck.

eepers

Do the other GWS warplanes tend to be tail heavy? I suppose the 400 motor would help counter that, but with the 300 I'm just making the problem worse by having a lighter battery up front. Looks like there's lead near the nose for me, haha.

scott88-RCU

My Feedback: (1)

The Spitfire is but I didn't have the same problem with the Zero. Right now I'm having problems with making the Spit be stable so I moved the cg forward and reduced servo throw and am still waiting for a calm day.

eepers

UGH!

OK, so, just got a new ICS-300E controller, and a 9.6v700mAh NiMH battery pack. (to refresh memory this is on a GWS speed 300 motor).

I charge the battery @ 1 amp until it swaps to trickle charge. I put both in and start to throttle up.... going good, I hit about 70% throttle and the engine cuts off. I go back to zero. I start raising it again, it gets to about 55% throttle and cuts off. I reset to zero throttle, try again, gets to about 20% and cuts. It hovers about 10% throttle after that over and over.

So. Anyone know what to make of that? Is the 300 controller too big? Nothing felt hot or smoking immediately afterwards. Am I charging it wrong somehow?

Flounder44

Park Flyer mag has a "hop-up" for that plane that calls for a AstroFlight Mighty Micro 010 brushless and a Kokam 2-cell, 1500 mAh Li poly that is supposed to extend the flight duration to 25 minutes. It's in the March/April 2004 issue - pg 41.

eepers

Haha, "hop up" nothing... I just want it to run for long enough to get off the ground once. I'll check the article out anyway though (did you mean 2003?), I really like that mag.

I can run the motor full throttle for about 30 seconds with my old 8.4v600 mAh, and virtually not at all with 9.6v700 mAh.


(The whole thing is just really silly, I have yet to have something work right in this entire RC endeavor, short of the RealFlight simulator.)

Flounder44

No, actually it's the Backyard Flyer March/April edition that I received in late December. I don't understand why they do that either - but they always send out the magazine months before the actual date on the cover.

clively

I don't know if you're still trying to figure this out or not, but if you are going to stay in electric, invest in a Astro Flight Whattmeter. It will tell you pretty much everything you want to know about the power drain on your setup.

That motor is pulling somewhere between 6 to 8 amps out of those batteries. This means your 9.6v700 NiMH is giving the juice at about 8.5 to 12C ; and the 600 mAh at around 10 to 13C or more. Your shutdown could be due to the voltage drop from the batteries being sucked dry so hard. Basically, the auto-cut off circuit is kicking in. Given that the auto-cut off on the ICI-300 turns on at 3.2V, you may have already killed the batteries.

It's also possible that a cell or two in the packs were bad to begin with. If possible, find someone local to check the packs out.

BTW, due to the low (1.2A) BEC circuit, this ESC really should be kept in the 7.2 volt range to avoid having your control surfaces going non-responsive during flight. Regardless, pay attention to the servo count / cell count chart.

If the motor is the 300C, then I'd either retime it (search RCU) or just replace it with a 350C or Graupner 6V Speed 300 (they're the same motor). Speed 400's are *generally* considered overkill and you should see the same performance out of the 350C.

Next I'd return those batteries and ESC. 8.4V or above will just burn out the 300C and 350C motors in short order. The brushes don't deal with that current level to well.

Finally, I'd invest in some li-poly's (2S1P configuration) and a good ESC from Castle Creations. Either the Kokam 1500HD's or the Thunder Power 1300 or 2100's, the GWS Foamie's beg for 'em.

Good Luck.

eepers

Thanks Clively, very helpful. I'd like to say I've got it worked out, but the weather has been pretty poor for testing... so... I'm only hoping here. I asked in another thread about charging rates and found that I was charging the batteries too fast and it was kicking to trickle before ever really getting that packs charged.

But something you said interested me, about the 8.4 and 9.6V batteries burning out that motor quickly... You're suggesting I use a 7.2V battery? Is that underpowered?

clively

Hi Eepers,
There are two motors that GWS packs with their warbirds: 300C and the 350C. These motors are the same as Graupners Speed 300 7.2V and Speed 300 6V, respectively. Which in turn are both produced by Mabuchi.

The 300C's (Speed 300 7.2V) operating voltage range is 6.0 to 8.4V. The 350C's (Speed 300 6V) operating voltage range is 1.2 to 6.0V. Generally you can get away with going one step higher than recommended. In this case, the 350 will be okay with a 7.2V pack and the 300 will be okay at 9.6V pack.

Any more than that and you will burn the brushes right out of the motors pretty quickly.

The 300C is a gutless motor and requires the bigger battery pack to spin. The cheapest upgrade you can do is to dump it in favor of the 350C.

skypupmut

if your batt pack is NIMH you have to form charge them first
C10 15-16 hrs then you can fast charge otherwise they will not give you full power or take a full charge

netitibydow

I'm getting a GWS Zero and I want to use li-poly in it. The kit includes a 350C motor. Can i use this motor with li-polys and if so what sort of ESC do i need? Also, will the RX work with li-polys or do i need a special one of those too? I'm new to Electric, so any info would be nice.
Thanks,
Chris Patten

clively

Hi Chris,
Yes you can use li-poly's. Look at the Kokam 1500HD, Thunderpower 2100, or the E-tech 1200. Get a 2S1P or 2S2P configuration which will put out 7.4 volts to be safe with that motor. The motor will draw upwards of 8+ amps so make sure the cells you choose can support that type of draw (search RCU for more info on specific cells).

Besides charging, the main difference between Li-po and NiCad/NiMH cells is the voltage point where the cell can become damaged. Most ESC's with a BEC have this voltage point hard coded into their software for the NiCad/NiMH cells. This point is too low for li-po's. If a li-po cell is drained too low it will either never take a charge again or could cause a fire.

Castle Creations, www.castlerc.com, makes a couple ESC's with a programmable LVC such as the Pixie-20P. I believe FMA direct and a couple other manufacturers also make li-po friendly ESC's. I use the Pixie.

Concerning the receiver, any will work. Just stick with one that is fairly low weight (0.5 ounce or less). In electrics, weight is of prime importance.

Good luck,
chris.