Hello,
I am going to make an rc boat and i bought a brushless motor that has a max pull of 800g as it says in the specs. Does that mean that the hull and the components inside the boat can't exceed 800g or else the boat wont move?
The motor is Turnigy D2836/11 750KV Brushless Outrunner Motor
Link to datasheet or product page please. Give us all the info, not just a part number.
sirick:
Does that mean that the hull and the components inside the boat can't exceed 800g or else the boat wont move?
As @MarkT has said you need to post a link to the specs for the motor.
The thrust from an engine in a boat depends as much on the propeller as the motor.
The weight of boat that can be moved has no simple relationship to propeller thrust. I own a 14 tonne boat and I can move it by pulling with a rope. My muscles certainly can't produce 14 tonnes of thrust. Boats provide a nice opportunity to experience the reality of the formula F = M * A (force = mass times acceleration).
...R
Robin2:
As @MarkT has said you need to post a link to the specs for the motor.The thrust from an engine in a boat depends as much on the propeller as the motor.
own a 14 tonne boat and I can move it by pulling with a rope. My muscles certainly can't produce 14 tonnes of thrust.
...R
LMAO
ok here is the link Amazon.com
it well be assembled with a Φ40 pace 21 shaft M4 propeller and a Μ4 x 210 mm MPJ stuffing kit
sirick:
LMAO
I didn't realise I had said anything funny.
From a quick look at your link I think the thrust figure is for an airplane propeller. I doubt that it has any relevance for a marine propeller.
If you really want advice about boat propulsion I suggest you ask on a Forum dedicated to model boats. There is a huge technical difference between the drive for slow models such as tugboats and what is needed for racing boats.
...R
Yep that's intended as an aircraft motor (the hint is in the "Prop size" parameter). But even with an aircraft 800g thrust doesn't mean the plane must mass less than 800g UNLESS you want it to climb vertically out of your hand. For a slow flying oldtimer 2-2.5Kg would fly nicely.
I don't know enough about model boats and the efficiency of boat propellers to say much more but certainly 800g will NOT be a limit.
Steve
You have some handle on the performance - its run from 7.4 or 11.1V, at 14A or so, so 100 or 150W
is possible (it needs forced air cooling being an outrunner, note, which is a non-issue for aircraft, but
matters for boats.
The power requred to accelerate water to speed v is very very roughly 1/2 M v^2
where M is the water mass flow rate though the screw and v is the ejection speed.
I'd suggest looking for an online calculator for RC boat motors and props.
Side note....
I Giggled 