Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Brushless motors for large Perkasa  (Read 1583 times)

Dave Cook

  • Cookie
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 202
  • Keep on Rockin
  • Location: Lancashire
Brushless motors for large Perkasa
« on: June 19, 2014, 08:08:23 am »

Hi All, When i asked the question on the best power train for my 1:24 scale Perkasa i have been strongly advised to go with Brushless motors and Lipo batterys . Is there anyone out there with this size of boat who could give me advise on this E.G Number of motors and which ones . Number of Lipos and there size . A suitable ESC ( one or two ) . And size and type of Props . This will be quite a heavy boat packed with a lot of electronics E.G P100 sound unit , P101 amp , 3 inch speaker , Water pump , Motorized guns, And hopfully working torpedoes . If anyone can help that would be great.
Dave  :-)) :-)) :-)) :-)) :-)) :-))
Logged

Time Bandit

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 175
  • Model Boat Mayhem is Great!
  • Location: Deizisau, Germany
Re: Brushless motors for large Perkasa
« Reply #1 on: June 19, 2014, 10:28:28 am »

A friend of mine runs his "Strahl" (which should be exactly the same hull) with 1 900 size motor on 24 NimH cells.
This thing runs perfectly, I just remember he told me that weight was a big problem with the boat. If it is too heavy it is not running anymore.

If you really want to go with brushless motors I personally would use 2 motors. The rest is a bit hard to answer of no boundary conditions are known. So Iīm trying to guess a little bit.

So letīs just guess you are using 50mm brass props and you want to go 20 km/h the motors must have around 10000 revs under load.
At 4S Lipo this would be around 750kv.
At 6S Lipo 500kv.

So with 2 of these http://www.hobbyking.com/hobbyking/store/__28693__NTM_Prop_Drive_Series_42_58_500kv_1300w_UK_Warehouse_.html you will be absolutely safe, also if you want to use bigger props or racing props with higher pitch.
They will provide you each with around 400-500W without generating heat problems.

These ones here for 4S
http://www.hobbyking.com/hobbyking/store/__38034__Turnigy_Aerodrive_SK3_4240_740kv_Brushless_Outrunner_Motor_UK_Warehouse_.html
But with these you shouldnt overdo it regarding speed.
They are suitable for 20 km/h but probably too small for higher speed.

ESC:
I always use the Roxxy 9xx ESC in my brushless boats, because they are simply the best I know.
Very good starting of the motors and smooth running also at low speeds (but still not comparabale to brushed motors).



Logged
regards

Tobias

wizard

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 32
  • Location: Buderim, Queensland
Re: Brushless motors for large Perkasa
« Reply #2 on: June 21, 2014, 02:48:50 am »

Hi Dave,  I have a 1:24 scale Dark class, about 920mm long. It has lights and rotating radar which have their own batteries.
I have twin 40mm props. twin Hobbyking flight 28-36  1800kva motors and twin Hobbyking Boat 30 amp speed controllers run by 3S 11.1 V  25-35c 5000 mah lipo battery.
The ESC are water cooled the motors not but no problems with heat.

The only problem I have is that it's well over scale speed so I will probably downsize the battery to 2S 7.4v


Wizard
Logged
we never really grow up, we only learn how to act in public.

nick_75au

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 257
  • Location: Brisbane, Australia
    • Logan City Marine Modellers
Re: Brushless motors for large Perkasa
« Reply #3 on: June 21, 2014, 05:11:15 am »

You can do it with brushed motors, John Darke has done a heap of trials, the boats he sets up use 4:1 geared 700 motors and recently Lipos, but I agree with Time Bandit on the brushless advice, it is the same as I would give. Never had a problem with the HK ESC's but each to his own ok2 
Logged

mudway

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 478
  • Model Boat Mayhem is Great
  • Location: Sydney
Re: Brushless motors for large Perkasa
« Reply #4 on: June 21, 2014, 08:19:28 am »

I thought John Darke had gone out of business years ago.
Logged

nick_75au

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 257
  • Location: Brisbane, Australia
    • Logan City Marine Modellers
Re: Brushless motors for large Perkasa
« Reply #5 on: June 21, 2014, 08:46:10 am »

I don't know all his business but he has been coming down to the lake on a semi regular basis, saw him last Sunday :-)


Nick
Logged

inertia

  • Guest
Re: Brushless motors for large Perkasa
« Reply #6 on: June 21, 2014, 08:57:49 am »

John gave up his mail order business a while back but he still builds models to order and, of course, has his own models (including "Sergeant Darke - the modified Perkasa). Pass on my best wishes to him next time you see him please, Nick.
Dave M
Logged

mudway

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 478
  • Model Boat Mayhem is Great
  • Location: Sydney
Re: Brushless motors for large Perkasa
« Reply #7 on: June 21, 2014, 09:44:12 am »

We haven't seen John or his Perkasa with its awesome power and noise generators down this way for some time. Last time was out at Hubertus for their annual show some years back. His "big" Darke motors were quite useful.
Logged

inertia

  • Guest
Re: Brushless motors for large Perkasa
« Reply #8 on: June 21, 2014, 09:50:39 am »

His "big" Darke motors were quite useful.
I know! I have a couple of the planetary-geared ones here and on 20 cells they sound like a power drill!
DM
Logged
Pages: [1]   Go Up