I've got a ace/thundertiger seamaster with a saito 56 and a 13x8. I'd like to convert it to an equal performing brushless lipo setup. Suggestions? Experience? Thx.

There are 3 versions of the Ace Seamaster that I know of from .40-size ARF to a .60-size ARF to a 1.20-size kit. Is yours the .40-size version?

Specs:
Wing Span: 59.5"
Wing Area: 725 sq in.
Length: 54"
Weight: 7 lbs.
Engine: .40-.46 2-Cycle
.54-.60 4-Cycle
Radio: 4 Channel

Oops. Sorry didn't realize there were multiple versions. Yes mine is the 40 size. If there is such a thing I've got clearance for a 13.5" prop. Got the following recomendation at ezonemag.


"Besides Maxcim, an Astroflight Brushless 25 geared motor or an AXI 4120/18 will work well. Get a 5s Tanic pack that is capable of 50 amps and a Castle Creation 45 amp or greater controller. You will also either need a Rx battery or a UBEC for the servos. I would suggest the UBEC.

Your biggest issue will be the limit on prop diameter due to the pylon. How big of a prop can you mount on the pylon?

http://www.astroflight.com/e/env/00...oducts:af-825gm

http://www.hobby-lobby.com/brushless-axi4120.htm

http://www.tanicpacks.com/

http://www.koolflightsystems.com/ultimatebec.htm"

I'd appreciate your feedback.

Thanks. -steve-

Those are all good suggestions.

Since you are limited to a 13" or possibly 12" prop length, you could also use a 3-blade prop which gives you an effective added inch. (i.e. 12" 3-blade = 13" 2-blade)

Also, using two 3-cell packs in series can alleviate your charger requirements from a 5-cell pack. Using two 3s packs in series gives you a 6s voltage equal to 20 cells NiCd. This is within the AXI 4120/18 specifications. Use a Lithium pack that can deliver 40amps (or more) continuous like the [link=http://www.hobby-lobby.com/thunderpower.htm]ThunderPower 3s2p 4200mAh[/link] pack or the [link=http://www.hobby-lobby.com/kokam.htm]Kokam 3-cell 3.2AH[/link] pack. On a plane this size, the shape of the pack may be your determining factor.

Good luck!

Thanks Greg,

Sorry to be so ignorant but if I'm using a 13x8 now with my Saito 56 would you suggest the same prop for the electric conversion? Will this setup give me 15 minute flights? Is there an issue with battery heat? Probably not a good idea to cut cooling holes in a flying boat. Is the Astro-flight lipo charger still the way to go? Controller preference? Finally it seems that electric is a lot more variable in the parameters than IC. Is there a good FAQ/Electric for Dummies primer? Thanks.

Steve,

You could use the same prop, but, often in electric conversions, we prefer to use the largest prop that clearance allows unless it's a scale plane.

The flight times will average around 7 minutes depending upon how hard you fly. The Seamaster is very aerobatic!

I would check the battery temperature after the first couple of flights. The longer you fly, the warmer the packs will likely get. I have always wanted to convert a Seamaster but just haven't done so yet.

If you use a Jeti 77-amp Advance PLUS ESC, you won't need to worry about cooling it.

As for the charger, to charge the 6s configuration as a whole, there still are not many choices other than the AF Lithium 109. Simply remember to always watch the cell count in Mode 1 (first 3 minutes) and always spin that darn current knob to minimum before starting a new charge cycle.

If you split the packs back into two 3s packs for charging, buy two of the [link=http://www.hobby-lobby.com/chargers_lipoly.htm]ETC2500[/link] chargers that work on 1-4 cell packs.

The fact that you know what questions to ask means that you already have good knowledge about electric flight.

Thanks Greg!

OK. I'm digging into this some more and have a few more questions/conerns.

I see that the axi 4120/18 is advertised for 6.5 lb planes. (Yet they also claim it has the power of a 4 stroke 90!) I think my Seamaster is about 7 lbs. Also it looks like with the motor and sets of batteries that it will weigh an extra lb. (Or maybe verses a full 8 oz glow tank an extra half pound.) So should I have concerns about this combination?

Generally with my Seamaster I'm doing a little aerobatics but mainly shooting touch and goes. Also turns out that I'm using a 12x6 with my Saito .56 but a 13" will fit.

It looks like perhaps I can fit the batteries in the glow fuel area behind the engine in the pod. (If the CG works out.) Maybe I can even put some cooling vents in the pod since its away from the water. (I notice that the lipo battery suppliers 'insist' that batteries are taken out of planes for charging.) Really?

So I can only get 7 minute flights and then I got spend more than an hour between flights recharging (or spend another $300 for another couple of batteries.) yikes!

Looks like for the bigger amp batteries the AF 109 might be a better choice as it will charge faster. Correct?


I see that hobby lobby packages the 4120 and jeti 70 for a savings. Does using the 70 add some risk?

Thanks again. -steve-

Steve,

I'm not sure what you are asking about when it comes to your concerns and risk.

Typically, you can recharge in about 40 minutes since you don't use the full pack capacity.

Oh I meant risk with regard to using the 70 amp version (because its bundled with the motor) over the 77 amp version. Its still pretty confusing to me trying to figure out amps drawn etc. Any comments on my other conerns? Thx. -steve-