Delta force build

[Chuck E Cheese]

ok that data looks more like it... i wont even refer to the previous thread but it looks like you are getting there. the loaded rpm seens pretty high at 39k with a feigao, be careful so you dont waste the bearings. also watch out in "proping up" when allready pulling 108 amps. instead of proping up you might want to start reading up on working props. by detounging a prop properlly you can decrease the amps and increase the speed. your set-up would probablly like a detounged x642 alot better than that grimm prop... keep going and learning, boats are alot different than any other RC vehicle, the amperage is high and every MPH is expensive..

[Brushlessracev]

ok that data looks more like it... i wont even refer to the previous thread but it looks like you are getting there. the loaded rpm seens pretty high at 39k with a feigao, be careful so you dont waste the bearings. also watch out in "proping up" when allready pulling 108 amps. instead of proping up you might want to start reading up on working props. by detounging a prop properlly you can decrease the amps and increase the speed. your set-up would probablly like a detounged x642 alot better than that grimm prop... keep going and learning, boats are alot different than any other RC vehicle, the amperage is high and every MPH is expensive..

Should i have got with a higher amp speed control. the first few times i ran my rudders had debree in them and was blocking water flow and i was hitting thermal shutdown. but know i have the temps under control i can run for a full battery. i may have the settings wrong for my RPM senser do you know how many Polls the feigao motor has i cant find that info anywere that 39k seems a little high too me too, thats telling me that the prop is not in the water or a have too small a prop or setings are wrong. i thougt it was a 2 poll motor but that looks wrong.

[Chuck E Cheese]

it is a 2 pole motor. what you need to look at is the rpm during playback (set up a guage on the display instead of just numric rpm). if you were draging a leaf or something that will raise the amperage also. a 120 amp esc should be plenty, that motor should be peaking out around 90 if all is set right. is the boat running wet (nose heavy)? that will creat high amp draw and excess heat. try and get a video and your exact set-up and i can help you out. you should be getting low to mid 40's on that set-up. be careful, a bigger prop isnt always the answer, that is how you smoke esc's. sometimes a smaller prop actually spins faster creating lower amperage and higher speed. if you have one try the 437-3 that is a kick ass prop on that hull. with a ammo 2300kv on 4s with a 120 esc i was getting around 45mph in a DF 26 copy.

[Brushlessracev]

it is a 2 pole motor. what you need to look at is the rpm during playback (set up a guage on the display instead of just numric rpm). if you were draging a leaf or something that will raise the amperage also. a 120 amp esc should be plenty, that motor should be peaking out around 90 if all is set right. is the boat running wet (nose heavy)? that will creat high amp draw and excess heat. try and get a video and your exact set-up and i can help you out. you should be getting low to mid 40's on that set-up. be careful, a bigger prop isnt always the answer, that is how you smoke esc's. sometimes a smaller prop actually spins faster creating lower amperage and higher speed. if you have one try the 437-3 that is a kick ass prop on that hull. with a ammo 2300kv on 4s with a 120 esc i was getting around 45mph in a DF 26 copy.

That explains i had it set to 3 pole. no its not running wet if enything its not going on plain rear is draging some. I need to move batterys fowerd some. i have a proboat 40x38 prop i was going to try its the same as the x442 but carbon.

[Brushlessracev]

it is a 2 pole motor. what you need to look at is the rpm during playback (set up a guage on the display instead of just numric rpm). if you were draging a leaf or something that will raise the amperage also. a 120 amp esc should be plenty, that motor should be peaking out around 90 if all is set right. is the boat running wet (nose heavy)? that will creat high amp draw and excess heat. try and get a video and your exact set-up and i can help you out. you should be getting low to mid 40's on that set-up. be careful, a bigger prop isnt always the answer, that is how you smoke esc's. sometimes a smaller prop actually spins faster creating lower amperage and higher speed. if you have one try the 437-3 that is a kick ass prop on that hull. with a ammo 2300kv on 4s with a 120 esc i was getting around 45mph in a DF 26 copy.

That explains i had it set to 3 pole. no its not running wet if enything its not going on plain rear is draging some. I need to move batterys fowerd some. i have a proboat 40x38 prop i was going to try its the same as the x440 but carbon.

[Chuck E Cheese]

COG (center of gravity) should be right around 30% of the hulls legnth. make sure to get that right. start with the strut flat with the bottom. read some of the previous threads on this hull and it will help alot. here you can see pictures of one of my old ones.
http://forums.offshoreelectrics.com/...ad.php?t=11912

[Brushlessracev]

COG (center of gravity) should be right around 30% of the hulls legnth. make sure to get that right. start with the strut flat with the bottom. read some of the previous threads on this hull and it will help alot. here you can see pictures of one of my old ones.
http://forums.offshoreelectrics.com/...ad.php?t=11912

I have it at 9" from trans that is 2/3 from bow or 30% from trans. 3/26=8.66 what was your strut angle or stinger, was yours adjustable.? i should get more lift from my duel rudders but i dont. torqe roll is none thought there would be some.

[Chuck E Cheese]

try and move the weight back to 8.5", 30% is on the max side (actually want between 27 & 30%). as far as lift from the rudders i feel you might not be getting extra lift but just the oppisite. i have never used duals but i do know that if one rudder is to long it creates drag, lowering the rear. run the strut or stinger flat at first. try getting more lift from the trim tabs, angle them down 1% at a time. the basic principal is that the strut is used to raise or lower the front of the boat while the trim tabs raise the rear by creating lift. torque roll has never been a problem. how long are the rudders (below the lowest part of the hull)? you may consider taking one of the rudder blades off just as a test, i know you like the look and cooling but just test it without one. if it handles better and you still want to try 2 they might need to be shorter so they create less drag

[Brushlessracev]

I just went and did that set it at 8.25 witch is even closer to the 27%. i have my battery's Velcro-ed in so they are movable. Rudders are only 1 3/4 below the bottom of the trans. I can not remember but i think negative caster on the rudder will give it lift. i have not messed with rudder caster yet. I am not too concerned about top speed just need the boat to accelerated fast out of the corners. so i am not worried about the extra drag of the rudders its really not going to make that much a differences. its like taking one knife and running it through the water and then taking two you really can not tell the difference at low speed. My next build i am going to do twin screws and no rudders. the only drag it will have is just the props. This build will be for top speed i want to brake the 100mph barrier it should be fun.

[wparsons]

Rudder angle really only gives lift or drives the nose down when you're turning, going straight (unless you need decent rudder deflection to go straight) it won't really do anything.

I'd say the RPM reading is definitely off, since it would need 17.3v to hit that RPM with a 2300kv motor. If the problem was that it was set to 3 poles, then your true RPM is more like 26578, which seems a bit low for a 2300kv motor. You should be getting around 35k unloaded, dropping 8000rpm under load seems a bit much. I'd try a touch smaller prop and see if unloading the motor a bit gives you any more speed.

Just noticed the low pack voltage, that's pretty low (3.32v/cell), if you weren't hitting the LVC then you might need higher C batteries to keep the current and voltage up.

Question on the eagle tree stuff, how does it not get a longitude or latitude fix, but can record a speed? Seems like a bug in the software, or is it just a setting?

[Brushlessracev]

Rudder angle really only gives lift or drives the nose down when you're turning, going straight (unless you need decent rudder deflection to go straight) it won't really do anything.

I'd say the RPM reading is definitely off, since it would need 17.3v to hit that RPM with a 2300kv motor. If the problem was that it was set to 3 poles, then your true RPM is more like 26578, which seems a bit low for a 2300kv motor. You should be getting around 35k unloaded, dropping 8000rpm under load seems a bit much. I'd try a touch smaller prop and see if unloading the motor a bit gives you any more speed.

Just noticed the low pack voltage, that's pretty low (3.32v/cell), if you weren't hitting the LVC then you might need higher C batteries to keep the current and voltage up.

Question on the eagle tree stuff, how does it not get a longitude or latitude fix, but can record a speed? Seems like a bug in the software, or is it just a setting?

just the setting on the gps. the low pack voltage was when it was dead that is cut off voltage. i am going to try sharping and balancing the prop to see if that gets the loaded rpm up. this grimracer prop was not even close to be balance or sharp for that matter. also the timeing on the motor is set to zero thats another thing i have not messed with.