Best Electronic Speed Controller for Class 7 BB

Forty-five minutes with two 12ah bricks sounds pretty good to me... I'll be running three 12ah SLAs in my monster when I rig it for combat, which when you consider the two extra guns and their power systems ought to give me similar performance, if not a little better, at least if I do it right. That is highly encouraging.

 

My Iowa runs 2 550s on a 14 pinion gear coupled to a universal socket and dogbone at 6v with 2 in 25 pitch 4 blade BC props. No Esc just a MAG throttle system . On it's first test run yesterday it ran well above speed but with the drag discs it ran to speed and turned very well. My Yamato uses the same set up but with a 12 pinion gear tooth and it clips along nicely and turns well. Roma uses same system as well and with no drag props and 1.75 props runs very well. All models have very long running times even with the pump on. I use a large nimh 4000 and 5000 millamphr battery for the receivor and servos seperatly and their good for several hours. Roma uses 3 SLAs at 6v and Iowa and Yamato have 4 SLAs at 6v. I have a Traaxis gear box system in Yamato and Roma and Iowa use the BC gear box system. One is the molded inclosure kind the other is the open style. Bismarck uses direct drive 970 motor 12v but I run it at 6v and even that's more than enough power I run Bismarck on only 2 6V SLAs and a seperate RX battery MAG throttle system setup. Drag props are attached. The prop is 2.5 dia 4 blade. Evenwith this the model performed excellent at 2010 IRCWCC NATS.

 

From what I've been reading so far from various responders, it looks like most of you guys are running props sized at least 1.75-inches in diameter or larger; I'm running 1.5 inch-diameter props, but they have 35-degree pitch, which seems to me that while the screws will have increased bite at a smaller size, they might be doing the same work as larger screws with lower pitches, and thus the motors are working at the same intensity as if they were spinning larger screws. Maybe. Am I making any sense at all? Heh.

 

My Richelieu originally had 1.5" props. Although it made speed without any trouble, the acceleration and deceleration was really bad. It took at least two full ship lengths to stop, and seemingly forever to get moving. Luckily, there was just enough room to squeeze in 1.75" props which helped immensely.

 

Iowa should have 2" 4 or 5 blade props on it. If you want it to be as good as it can be in battle.

 

It has yet to be proven that the big prop = best performance mantra I have been hearing lately is correct. I actually improved my I- boat's acceleration tremendously and turning slightly by switching from low rpm and 30 degree 1.5" props to high rpm and slightly lower pitch 1.0" props. Went from Wah-ming motors which are about 4000 rpm to a pump type motor geared down 1.33:1 and turning the prop around 9000 rpm out of the water. I recommend you experiment if you have the time and resources.

Ron Hunt

 

Agreed. I actually did a side-by-side performance test with four perfectly identical transport ships I built myself. Three different systems were tested: 1.25" 4-blade prop and RS-365SH motor, 1.3" 3-blade prop and RS-365SH motor, and 1.25" 4-blade prop and 5:1 geared 280 motor. When adjusted for identical top-end speed, the other handling was identical. I actually drag-raced them and all three systems tied. Same thing with turning radius, speed through turn, etc.
I believe there is a correct size of prop for each different hull size and shape. If you go too small OR too big, you'll lose performance.

 

When I arrived at Nats last year Bismarck had the strike 1.25 5 blade 35 pitch. Even with that small prop the model still ran fast and needed drag props . The turning was no different than with the large 2.5 in prop. Just to show that even a small prop with a certain pitch can work just fine. Hull shape beneath the waterline may have an effect in a small way as well. Most people in Fast Gun go with a ESC and drag props with very large props . I seen mostly 3 Blade props at High Rpm give the kind of wash over the rudder for fast turning. Everybody has found what works for them and most systems are not the same but the overall result is achieved. It's true though what Kotori87 referred too for too small and too big. Performance is lost whether too little or too much. Some ships are overpowered too much and it affects their handling. There is a fine balance between the right motor and prop combo. There is a lot of useful info here from all the guys from their experience. I think you will find the right combo for your ship.

 

Thanks a million, guys, this is all helping me immensely; lots of good notes here. Because I'm not trying to make it to NATS this year, I'm mostly focusing on getting feet-wet, as it were; I ordered my 550 motors from Strike today, and I'm going to direct-drive them for a bunch of test and putter runs, then start adjusting from there if need be. I am expecting my boat to be overspeed at first, which will eventually necessitate drag discs or drag props, and fine-tuning the ESC. But, overspeed doesn't matter unless you're a duck in the way of my boat when I'm out puttering around, heh.

 

Sounds good. I speed tested my Iowa yesterday. It's running 26 sec. Not sure if the batteries are undercharged or the drag discs I have on it are just too large. I was having an issue with the port gear shaft. This time the pinion and large gear wheel both were worn down so much that the shaft was no longer making contact and stopped turning. I found the problem. The small pinion gear had a bit of a wobble when turning. I filed down the shaft on the motor to level it and attached another pinion. It worked much better. I tried a different pinion which fit much better on the motor shaft and had no wobble when secured. I decided to switch out the starboard or right side motor pinion for the new one . Tested both and seemd to work much better but I can't tell yet till I get a 3rd sea trial. I reduced the diameter of the drag shaft to see if the speed will pick up. More tests to come.