crispyspa

I really have no "home" for this subject as it is a cross between a boat and a plane, I talking about an air prop driven 3 point hydro.

I 'm having trouble picking a prop/motor combo that will be a reliable choice.

If I could direct your attention to the speed electric boat section as I have started a thread there [link=http://www.rcuniverse.com/forum/m_11540741/anchors_11541373/mpage_1/key_/anchor/tm.htm#11541373]ESC general question[/link]

This is the boat I intend on converting. The glow engine currently on there is a ST G2300 MKII. I know this is kind of out of place here, but I've no where else to go. The guys in the airboat section (including myself) have never done anything this big, and the speed electric (boat) people haven't either.

I guess what I'm after is to spin a 16x10 or 16x12 APC two blade prop at 10-12,000 RPM without overheating any of the components, especially the water cooled ESC......Please visit the thread I mentioned.

aymodeler

My Feedback: (3)

Here is a great tool for evaluating motor-prop-esc-battery combinations: http://www.ecalc.ch/

I don't see why you could not use this in your application.

Al

crispyspa

I saw that and have questions about it.

Under the General heading>motor cooling. Is that the cooling that will happen in motion or is it how cool I want the motor to remain?

Under the battery heading>cell capacity. Is there a difference between cell capacity and total capacity. If the battery is 5000mah, isn't each cell 5000mah also?

Motor heading> I don't see Tacon Big foot motors listed, do I just choose one at random?

aymodeler

My Feedback: (3)

I'm not sure about the cooling. I always just leave it at "medium". I think that it refers to the cooling environment that the motor/esc will be operating in.

For cells in series, then you are correct, the pack capacity will be the same as the cell capacity - you increase the voltage without increasing the capacity. If you were to wire packes in paralell, you would increase the capacity without increasing the voltage.

If you can't find your motor, then leave the selection as "custom" and fill in the Kv, no load current, resistance, etc. You should be able find the specs listed on the manufacturers website (or the reseller's).

I find it best not to overthink this too much at this stage. The great thing about this tool is that you can play around with different inputs and and see what happens ...

Hope this helps.

blvdbuzzard

What they mean by cooling is how much air flow is the motor going to get. On a plane, if it is tucked into a tight cowl, it will be a lot warmer then if it is in the open as your setup.

What does the boat weigh? Just a general question.

I have this setup. It may not have the RPM you want though. It is listed as having a pitch speed of 66 MPH


Motor
http://www.hobbypartz.com/96m607-big...325-295kv.html

I run it with a 6s battery and a 18X6 prop. But if you run a 16X8 or 16x10 prop you can get a higher pitch speed.

Best advice is to get a watt meter so you do not let the magic smoke out of some parts .

http://www.hobbypartz.com/aeo-p0-watt-meter.html

Buzz.

crispyspa

The boat weighs about 11 lbs without the engine.

someone explained the whole watts thing to me once, but I'll be darned if I can find the thread. How does one use the information given by the watt meter?
If I use this ESC, http://www3.towerhobbies.com/cgi-bin...&I=LXBRBA&P=ML I should have no problems with over drawing and burning things up? If anything goes it will be the motor, right? Or am I not understanding the concept? The electric thing is Greek to me.

Glacier Girl

My Feedback: (4)

You use the info from the meter to determine the health of your system. Like are you pulling too many amps or watts for your systems capabilities, is your pack drooping under load.

I looked through your other thread, and maybe it's just me, but it seems you are getting some bad info over there.
Some of those posts are down right wrong. Keep your battery wires short as possible, and do use caps on the motor leads if they are excessively long.


I ran a similar motor (EFlite 110/295 kv) with your proposed set up on Ecalc, and with 10S pack and either the 16x8 or 16x10 you are over amping the motor.

Drop down to a 14x10 on 10S would give you 211oz of thrust and a prop speed of 91mph, at 9687 rpms. Roughly 55 amps static.

That's over 1:1 on thrust.

If you need more speed, you use the watt meter to tune your system via prop size and pitch, while still keeping the amps/watts in their happy place.




Thing with electric is WATTS, how you get there your motor doesn't really care. Volts x Amps= Watts.


As long as you keep the watts where they belong you'll be good to go.

I use that Eflite motor and a couple similar KV and sized motors in a lot of planes. Anywhere from 6S to 9S power and run 16x8, 14x10x3, and even a 20x8 prop on them.
Use of the meter will let you know what will work and what wont.

crispyspa

OK, Confused here. I have a motor, batteries and a speed control on order, I input the values for those three things and a prop into the calculator and I get an error message that says "Your parameters lead to a calculation error"

[link=http://www.hobbypartz.com/96m606-bigfoot60-4030-400kv.html]motor[/link]
[link=http://www.hobbypartz.com/07e-c-seaking-80a-hv.html]ESC[/link]
and two of these
[link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=33255]Batteries (2)[/link]
I plan to use an APC 16x8 two blade prop. (Just a normal prop, not an E prop.)

What am I doing wrong, or do those things not work with each other?

blvdbuzzard

Well the 7.2 amps at 2 volts for a no load does not seem right?

What motor, ESC, battery do you have? Are they listed in the drop down menu's?


Buzz.

crispyspa

I've highlighted the links above, they were kind of hard to see.

Glacier Girl

My Feedback: (4)

Your motor specs are all wrong.
There is no way that would work. You have the resistance listed incorrectly, and the amp capability way off.

I used the E Flite 60 which is a 400KV motor, and it's specs, leaving all the rest the same in Ecalc.
Shows borderline excessive voltage 34.52
EXCESSIVE AMPS 105.44
EXCESSIVE TEMP 273 degrees

1.5 : 1 thrust and around 86 mph, for about 2 minutes before something lets go.

crispyspa

Except for juxtaposing the no load current values, (which I re-did the calc) I got the values from the HobbyPartz spec page for the motor. I think the calc requires a motor manufacturer to be input instead of a "custom" setting. Oh I see where I screwed up.

Anywho...the stuff I bought wont work then. Crap.

Recommendations? I want to get to 10,000 RPM with a 16x8 APC.

Isn't there a calc that you input prop and RPM and it gives a recommendation based on that?

What does it mean for the motor if everything is in "budget" but the watts are 500 over?

blvdbuzzard

Why do you need 10k RPM?

I run the Tacon 60 motor, 6s, 18X8 prop. Puts out a lot of thrust. It is right at 11 pounds of thrust.


Buzz.

crispyspa

I just figured that's what I need to break 50 MPH with this boat. The Super Tigre turns the 16x8 over at just under 9000 and It won't break 50.

blvdbuzzard

I have no real idea how fast the plane goes, but it does get up and run.

All I can say is try it and see how well it does. For more speed, drop prop length and add pitch.

Buzz.

crispyspa

A thread has been started of the conversion process for anyone who is curious. Hey , it may burst into flame the first time I hit the throttle....come see. LOL

[link=http://www.rcuniverse.com/forum/m_11565402/tm.htm]SI 1/4 scale 3 pt hydro electric conversion[/link]

flyingt5150

wingster

My Feedback: (26)

Looks like a Himax.

Himax Brushless Motors 30-200 Watts

flyingt5150

ron_van_sommeren

Partial straight copy of message #2. More similar messages as well.
Don't waste your time guys, spammer/scammer reported.

Vriendelijke groeten Ron
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