Darter King Project - The Return of The King
 

Ok, I finally got the i-believe proper equipments for the 45" Darter King 8)

I am gonna test it today. Who wanna bet it will plane haha. Do make suggestions for improvement if you have 8)

Feigao 580L Motor 1600KV
2 paralell 14.8V Lipo 5000Mah
55mm Prop Pitch 1.4x55=77.0mm or 3.03" (3 Blades)
100A RC Model (Ebay) Esc, with Fan cooling.

RE: Darter King Project - The Return of The King
 

Perhaps it might be more efficient to go the surface drive way with a flex shaft etc.
I have this hull too,its a nice looking boat and probably worth the effort.
Brod..

RE: Darter King Project - The Return of The King
 

Whats up chicken!!! Thought you got lost or something. Darter maiden voyage huh? That is one Big-_ss prop![X(] Hope the motor can turn it without burning up, its gonna be close. Be sure to check your temps after 30 second full throttle (i read that on offshore) you should be able to touch it without yankin your hand back. Seriously though.................that prop is waaaaay big for a submerged prop. Dont fry your motor.................let us know how it does.:D

RE: Darter King Project - The Return of The King
 

Ok, I am back. It was a mixed experience.

Bad news first, batteries couldn't handle it. They got REALLY hot. After 7 minutes drive home, i checked them with the thermalmeter, it was still 68C. The wire and the ESC got real warm. And it was just about 2 minutes run. I should have stopped and checked after 30 seconds. The good thing, the motor was cool and the boat ran fast. One of the battery cover melt, but still in shape. I don't know if i should continue to use it. Anyway, help me diagnose the problem. The battery rated 15, continous about 10C, i ran in paralell so i had total of 20C.


Here is the video 8)

http://www.youtube.com/watch?v=S4lZHKLgpwM


Rebuilder: The 580L Fiegao is very torquey. It handled the prop no problem but the battery and the ESC were having a bit issue sustaining the motor. I am gonna water-cool the ESC and i guess i will have to get higher C batteries. Perhap i should use a smaller prop too 8)

RE: Darter King Project - The Return of The King
 

according to FECALC that setup ....Feigao 580 8L on 4s pushing an Octura x455 is drawing ~ 175 amps [X(]

Steve

RE: Darter King Project - The Return of The King
 

F********. Seriously? I knew that i should get the amp meter before. 8( I thought the motor's max amp drawn (85A) is the limit.

RE: Darter King Project - The Return of The King
 

Okay....................did the esc ever shut down? If not cooling it should help. If you have any wiring anywhere less than 12 gauge, that may be an issue (14 may possibly work) A N D your prop is waaaaaaaaaaaay tooooooooooooooo B I GGGGGGGGGGG . Did i read correctly that it is a 55mm? Thats over two inches for goodness sake! And its a submerged prop. Get a 442 or 445 and let the motor get up some speed and breathe. Your amping your whole system out. Somebody help me here.................45" Boat , 4s lipo, 1600kv motor = ????prop.

RE: Darter King Project - The Return of The King
 

The boat had 12 and 14 gauge wires. I ran it for only about 2 minutes and the ESC held up well. Just got warm that is all. You read it right, 55mm (AND 3 blades) 8) I guess my prop is big , but it is a big boat haha. Well, now i think about that, maybe should be smaller 8) I have a 52 but maybe that one is big too.

RE: Darter King Project - The Return of The King
 

try a x445 2 blade, i bet it will help a bunch, and you wont lose any speed i believe.

RE: Darter King Project - The Return of The King
 

Ok, i am gonna get blades about 47mm-to50mm 2 blades and try again 8). I hope the batteries are not dead yet. Will put it in metal pot when it is being charged it haha. The glue and plastic burned smell was toxic.

RE: Darter King Project - The Return of The King
 

47mm to 50mm are not 45mm blades;).....................................try some friendly advice!!:D

RE: Darter King Project - The Return of The King
 

Ok, i am gonna get 3 prop in the range 45-50 and run the smaller to bigger. Look like my battery is ok, accepting charge well and no swell yet. I read somewhere, the operating temperature can be around 60C. I i think only hit 70c or so. 8)

RE: Darter King Project - The Return of The King
 

;)
Brod..

RE: Darter King Project - The Return of The King
 

Two blade would be best..................... http://www.offshoreelectrics.com/pro...?prod=oct-x445

Or if you are so persistant heres a three: http://www.offshoreelectrics.com/products.php?cat=88 , try the 447/3

Good thing your battery seems ok.;)

RE: Darter King Project - The Return of The King
 

Second test with a 45mm bronze propeller (not sharpened yet, just balanced ) Do watch the clips in order. It was much better than the last time from heating aspect. The speed almost the same with the cover on. Batteries got a bit hot about 1 minute run and the esc and wire got a little warm. (Forgot my thermalmeter home.) I took the cover off and it ran much faster and everything was cool. Look like i have to get a better batteries and maybe higher (18) volt & add water cooling to the esc. Look like the 45mm did a good job 8).

http://www.youtube.com/watch?v=7vyXW57i5z4
http://www.youtube.com/watch?v=-T7jTbGjXwE


Without cover:
http://www.youtube.com/watch?v=U5sQjvCM3gA

RE: Darter King Project - The Return of The King
 

Hi Chickendog,

Running a stepped hull at that speed causes audible cavitating at the prop, due to the air being draw under the hull.

A surface piercing prop would be faster, but you'd lose the ECO style maneuverability, choices, choices...

My guess is the relative long and thin wiring has kept things from totally overheating in the( too) large prop testing phase, luckily the heat losses in the wiring didn't ge to the motor, the EC Lipo's really aren't up to high current applications, I have a few of them aswel.

Watercooling that ESC is easy, change the geatsink for an aluminum cooler like in the picture, not hard to make.
While your at it, check if the fets are in one plane, if not, sand them flat until they are, than add the cooler with some heatconductive paste.

The difference in speed with and without hatch is remarkable, it seems adding cooling really will make a difference.

Regards, Jan.

RE: Darter King Project - The Return of The King
 

Ckickendog- "Look like the 45mm did a good job" , "The speed almost the same" ....Hmmmmmmmmmmm, imagine that............where did you come up with that great idea?..........LOL:D. You can probably get away with fan cooling your esc......or just taking two copper tubes and laying them across the fins and securing them with heatconductive paste then running a SEPERATE water line to it................you have 3 intakes on the back still right? I' glad your boat is running better. As far as the Batts. are concerned, i am of the opinion that you have enough battery amperage..............2 5000 mah's running in parallel, right? If each is putting out only 10c continuous thats 50 amps cont. X 2 batts = 100 amps, you may be right on the edge of minimal amperage but unless you want to spend alot more $$ on 20-25C lipos, it should be ok, for "boat bashing". As far as the vids go, there is a very noticable diff. in the speed, insn't there, with the cover off...............or is that just me? The only other other input i have is that it looks like its running a "little bow down" can you move just a little weight backwards? Also..........................i have learned that at some point in the setup process you will get to what works well. I think you may be at that point....................if i were you, i would NOT change anything, especially the prop, just leave it alone and enjoy it (its very fast), you should be proud.:D Here is a link for a 5s lipo(18.5v), you could get two and run them in parallel for 10,000 mah and 200 amps!! (only $99 for both)

http://www.hobbycity.com/hobbycity/s..._20C_Lipo_Pack

P.S. - why do you put "8)" at the end of many of your sentences...........just curious.

RE: Darter King Project - The Return of The King
 

Sorry for late reply, got busy a bit. 8-)


Pompebled: i didn't know anything about cavitation. I googled and got the general idea but it wouldn't cause any serious problem right? I am getting a water cooling plate from offshore and thinking about poking holes on the cover for air to get in and out. I will modify in someway so that water spray won't get in.


rebuilder: the new 45mm prop reduces the Amp draw for sure and maintains pretty much the same speed. So, it does a good job 8) <- (that is me wearing glasses & smiling. I am nearsighted.) I am getting 45mm & 47mm plastic prop to test again. The ESC cooling late fins are too dense so i have to cut 2 out at least, and it is somewhat difficult. Right now, the boat is not fast enough to excite me so it has to be faster and faster. Perhap i watched too many high speed demonstrations from youtube haha. 8) I don't think i can move the batteries to the back so the only thing to do is RAISE THE VOLT to get it bow up. Thanks for the batteries link, they look good.

RE: Darter King Project - The Return of The King
 

Hi Chickendog,

You're right, as long as you have room to run the boat, drawing air under the boat isn't going to be a problem, unless you go much faster; the air/watermixture will reduce the drag, that's the whole point of having steps, but eventually it will reach the prop and leave your rudder standing in an airfilled bubble from the propwash, making steering an illusion, until you reduce the speed.
Been there, done that, very scary, running towards a brick wall without any response from the rudder...

Running a submerged prop will only get you so much speed; if you want to go faster, the first thing should be to remove the two obsolete propshaft bulbs, to get rid of the added drag, that will slow the boat down, pushing the nose down.
Next would be to sharpen the trailing edges on the step and transom, adding another 2-3 mp/h to the topspeed, without increasing the voltage.

If you have a cooling plate, please use it, cutting holes in a FE is always a bad idea, because you will flip it at some point, if you keep increasing the speed.

A serious gain in speed would be going to a surface piercing drive, no more drag from the propshaft and the prop under the hull.
Did I mention sharpening the trailing edges? It makes a very noticable difference...
Also scuffing the hull with 600 grid, lengthwise(!) will reduce drag.

Regards, Jan.

RE: Darter King Project - The Return of The King
 

You mean to sharp the leading edge, not the trailing right? I read somewhere that say to keep the trailing edge as square as possible. And i don't think the boat will flip easy since it was quite stable, a bit too stable to be fun. I make sure i can seal the holes when i want. I think that is important because i can't cool the batteries with water cooling. Surface piercing setup requires moving the whole drive train so i will wait on that.

I was too quick to say not being able to move the batteries to back. I can put one on each side at the back bottom and keep them in place with velcro. So third test with blades sharpened and air cool and plastics probs if they got here on time. I am going test till the low voltage kick in this time. Gonna see how long it can run on those two batteries.

"Also scuffing the hull with 600 grid, lengthwise(!) will reduce drag. " What is "600 grid"?

RE: Darter King Project - The Return of The King
 

600 grit sandpaper...

Steve

RE: Darter King Project - The Return of The King
 

Chicken: 8<) (thats me with glasses, nose and mouth;)) I thought about removing the other propshaft bulbs but didnt mention it for some reason........anyway, cut-em off smooth and I would epoxy a small square of aluminum flashing(hardware store) from the inside and then fill the small space thats left on the underside with epoxy and smoothe it really well. If you think about it they are creating a fair amount of unneccesary drag and pushin your nose down. Maybe that will keep the nose up without having to move batts and stuff. I read about scuffing the bottom of your hull with the sandpaper but what i read was more like 250 grit, it is supposed to let air bubbles attatch to the hull and the boat sits up on the "air shield", however, i have never done it, i dont want to rough up my smooth, waxed hulls, im just fine the way mine are. (8<) me again with hair now.[8D]

RE: Darter King Project - The Return of The King
 

Hi Chickendog,

Last time I checked the trailing edges were at the back of the boat, so we mean the same thing, the waterflow needs to break off at the step and the transom and not crawl up, creating drag. These edges need to be square and sharp.

Running a surface piercing drive will increase the speed and reduce stability, due to the fact there's much less in the water to stabilize the boat at speed, that should raise the 'fun' level

If all out speed isn't your goal, don't sand the bottom, but don't wax it either, you may like the shining surface, your boat doesn't, it will stick to the water creating drag.
I've been testing in the past with two identical hulls and set-ups, the scuffed hull was faster than the waxed one, not by a lot, but enough to be ahead at the next marker.... and that's what counts.
If you check pictures of (European) competition boats, they all have the bottom scuffed, the shiney airbrushed parts are on top...

Regards, Jan.

RE: Darter King Project - The Return of The King
 

Ok, 3rd test with just sharped prop and corrected shaft viberation. Batteries got overheat again so i couldn't run till they out of juice. I ran for about 5 minutes with 1/2 of the time open cover because batteries got too hot. Getting a thrust bearing and maybe new batteries.

Water was rough that day as boats ran by & ignore my voice.

http://www.youtube.com/watch?v=AyV4ZVET2D0




Dean connectors suck, too exposing. I accidentally burned a hole on my joint 8( and it was not the first time. Glad didn't kill the motor or batteries.

RE: Darter King Project - The Return of The King
 

Ok, which prop are you running now? You may think im crazy but you may need to go to an x442, remember you didnt lose any speed changing from that huge airplane prop you started with and you cooled everything down. You are pulling alot of amps still, and im betting your boat doesnt weigh much at all. Lemme know what prop you were running.;)