Technical, Techniques, Hints, and Tips > DC Motors (Brushed) and Speed Controllers
More power reqd.
Tug:
Change of subject here chaps,
The graupner 600 bb sp 7.2 Volts and running on 8.4 volts in the 3 foot torpedo boat, just aint' enough to get it up.
I expected about 25% more power.
The 50 Amp speedy. Gets rather as warm the motor almost too hot, though I can water-cool that.
She?s carrying a 40mm 2 blade prop, tried 40X not an improvement, lost the brass Prop Shop one, [crash stop]
Shipmate60:
I used a stock 550 motor on 8.4 volts and a 40mm fast scale prop from propshop, good speed and duration and no heavy current speed controller required.
Got a pic of her if you want to se4e the performance in a Deans 70ft gunboat.
Bob
malcolmfrary:
Hi Tug
You don't say what size (capacity) of battery you are using. Some several years back a friend did a Stepke lifeboat, and fitted it with his accustomed gel cell arrangement. The thing was sluugish and only ever had a short run time. When he replaced the gel cell battery with a 6-cell race pack, not only did it go fast enough to plane, but it ran about twice as long. Adding some lightness usually increases perfomance amazingly.
HS93 (RIP):
Have you got a rooster tail behind your boat?? I have a firetender 34" with two 700 bb on 12 volt n/cads tried all sorts of props, It had a sixfoot rooster tail and it did not mater how much power, it would not plane ,tried moving things about it was just to heavy Peter
Fast Electricals:
That is quite a large boat and a big propeller. The motor is likely to be overloaded and not working at its most efficient rpm. In my experience it is best to load the motor so that it spins at about 80% of its no load speed for maximum output power and efficiency. I have done some calculations for your boat and have worked out that if the set up was installed in a small light fast electic hull you should achieve about 18mph. Your hull is neither light or small and so a realistic scale speed would be about 9mph. The easiest way to achieve this speed is to try a 2:1 reduction gearbox. This will lighten the load on all the drive components and keep the motor reving within its power band. The weight of the boat is also important and should be kept to a minimum. What would you estimate the current on water speed to be?
Neil
Navigation
[0] Message Index
[#] Next page
Go to full version