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[Biggles]

Hi All


I have a Fairey Huntsman 33" with twin prop shafts and I'm thinking of changing the motors to Graupner 700BB Turbos, Can you run these motors in reverse as I want the props to turn in outwards directions.


Also what sort of batteries would you use with these motors, the previous was a sealed lead acid.


Any help gratefully received. Thank you.


Biggles

[Martin (Admin)]

Yes, they run very well in reverse.

You can run any battery you feel most comfortable with but Lead acids may not stand up too well to the punishment!

[red181]

I used these with great success (but brushless are better!)

Graupner motors have a nominal voltage range, use the top end of the range and you will get a good speed, but will probably have to water cool them. I tested quite a few, the 9.6v was the best for me, if you can get your hands on the neo version  (neodum  magnets, probably spelt wrong!) they are very good

[malcolmfrary]

Lead acids may not stand up too well to the punishment!

Not "may".  "Will" not stand the punishment is nearer.
A battery is needed that can continuously supply the required current and store more energy and be lighter.  Lithium sounds good.

[canabus]

Hi
If you are changing motors and maybe batteries??
Twin B28-57-15L brushless with water-cool engine mounts(on 3S(11.1 volt Lipo Batteries)21,090 rpm ,750 watts) these are Diameter 28mm x length 57 mm ,shaft 3.175mm).
Brushless 45-60 Amp ESC's.
Twin 3S 2650mah 30C Lipo batteries(weight 250 grams each).
Props 2 blade 32mm x 1.4 pitch or 3 blade 30mm x 1.4 pitch.
I have a single setup in my 25 and 1/4 inch Sea Hornet and it's a little rocket.
I lower rev motor would be the B28-57-17L which my mate has in his Sea Hornet.
Remember  750 watts equal one HP. 

[triumphjon]

i too have a huntsman , fitted with a pair  model motors direct 777 motors , ive tried both a single battery and a seperate battery to each esc/motor  and havnt been able to get the boat onto the plane , even from a 12 v supply , im currently fitting a piar of 28 mm dia  1000 kv brushless motors into a spearfish , with lipo batteries , if the performance is nearer to scale i shall be re motoring the huntsman too . motor / battery technology has come along in leaps and bounds over the last few years meaning we can finally get better perfomance than the glow engines

[canabus]

We have a club member with a Spearfish, it has a single Turnigy 3639-750kv on 3S with a 50mm prop 2 blade, we tested a 3639-1100kv on 3S and 4S and also a 3648-1450kv on 3S.
Performance was a bit over scale speed, to dam hoon, to insane.
The Spearfish handle all these tests with no problems!!! 

[inertia]

i too have a huntsman , fitted with a pair  model motors direct 777 motors , ive tried both a single battery and a seperate battery to each esc/motor  and havnt been able to get the boat onto the plane , even from a 12 v supply , im currently fitting a piar of 28 mm dia  1000 kv brushless motors into a spearfish , with lipo batteries , if the performance is nearer to scale i shall be re motoring the huntsman too . motor / battery technology has come along in leaps and bounds over the last few years meaning we can finally get better perfomance than the glow engines

John
The 777 is a very 'soft' motor and doesn't have the power required to propel a Huntsman, even when fitted in pairs. This is exacerbated if you then were to weigh the poor thing down with lead-acid batteries. You haven't said which Huntsman you have but it's bound to improve in performance with brushless motors and lighter batteries. Prop selection also is an important factor.
DM