Model Boat Mayhem
Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: explorer750 on October 30, 2008, 10:41:50 am
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Hi,
I have been looking at the new griffin 600 and am intent to fit a brushless motor. The other day I found on ebay a large selection of motors and speed controllers for really low prices ( about £8-9). Compared to paying £30 in a shop. My question is are they any good.
http://shop.ebay.co.uk/items/__brushless-motor_W0QQ_nkwZbrushlessQ20motorQQQ5ftrkparmsZ72Q253A1298Q257C39Q253A1Q257C66Q253A2Q257C65Q253A12QQ_dmptZUKQ5fToysGamesQ5fRadioControlledQ5fJNQQ_trksidZp3286Q2ec0Q2em14QQ_pgnZ1?_trksid=p3286.c0.m14 (http://shop.ebay.co.uk/items/__brushless-motor_W0QQ_nkwZbrushlessQ20motorQQQ5ftrkparmsZ72Q253A1298Q257C39Q253A1Q257C66Q253A2Q257C65Q253A12QQ_dmptZUKQ5fToysGamesQ5fRadioControlledQ5fJNQQ_trksidZp3286Q2ec0Q2em14QQ_pgnZ1?_trksid=p3286.c0.m14)
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Most of the brushless motors specs on ebay seem to be a little "exaggerated" so buy a motor 10-20% better
than what you need. Plus all normal ebay cautions apply!
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explorer
I have discovered that the Griffin is a hoovercraft - don't know what the proposize but lets guess 8 inch x 4 or 6
The ebay site your pointed to is heli - based, and all the motors I looked at are in the 4000 to 5000KV (Helis use BIG gears)
Say you ran only a 7.2 V pack this would give you 7x4000 rpm 28000 RPM at the prop which on an 8x4 is in the region of 2 KW (working from memory) and the tips would be well into the noisy sub-sonic region
These motors would be the canine pendular appendages if you were running a 4 inch prop, ducted fan impeller or waterjet, but I feel that someting in the KV1000 to 2000 range (aircraft) range would work more reasonably
I'm making lots of guesses, and relying on my memory a lot in this answer
andrew
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Palaform suggest a 400 size brushless motor 1100rpm/v or above. If you look in Model boat November issue their is a review. The prop they use is a APC 7x5.