Mfa spearfish power

[Roo Hawkins 1Participant @roohawkins1]

[Roo Hawkins 1Participant @roohawkins1]

Hi I am planning to build a spearfish kit I have . I am planning to use a brushless 4250-700kv I have spare on 5 lipo cells. What do members think. ??

[Chris FellowsParticipant @chrisfellows72943]

Hi Roo

The Spearfish is quite a big model so that motor should be fine. On 5S/18.5volts it will rev to 12950rpm unloaded so that is Ok.

Chris

[malcolm tyremanParticipant @malcolmtyreman17139]

Im a traditionist re the spearfish,

i run a torpedo 850 motor feeding from a 12 volt lead acid battery, it goes plenty fast.

[malcolm tyremanParticipant @malcolmtyreman17139]

i should have said a 12 volt gel battery, sorry.

[Charles OatesParticipant @charlesoates31738]

Hi Roo, I run a similar sized model, your motor and battery seems fine to me, it won't hang around. What capacity is your battery? Gel battery in a quick model!! , definitely not my way of doing things.

Charles.

 

Edited By Charles Oates on 17/09/2023 12:04:58

[ashley needhamParticipant @ashleyneedham69188]

Malcolm. When I bought my MFA Fantome, I thought I would build it exactly as per the instructions, and used twin 800 motors and a SLA 12v battery. It appeared to go ok, for a big model.

However, changing to a 12v NIMHstick changed the performance quite a bit. You lose shedloads of weight and the battery is able to deliver more current, for longer even on a 5000 mAh stick.

Similarly the outdrive Seahawk, 850 motor and 12v sla (used as I didn’t have a 12v Nimh then initially). Performance was good but so much better with the Nimh.

Lattery I changed the Seahawk motor for a 2600Kv inrunner (as it was in my spares box) and 3s Lipo and now it is ballistic!

ultimately, if you are happy with the sla and you use it on other things….keep it! A 12v Nimh is not cheap now so it’s a balance between wallet and the amount of time you spend on the water.

Ashley

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