新手有野想問

大家好,想整隻船仔比我個女玩.摩打是540.電是3000mAh

試水好快玩完.船長21吋.是要裝嗎?謝謝

波箱?????裝左会好好多,還要視乎車葉大小决定一比二或一比三波箱

If not use波箱, but use smaller propeller, 效果是否一样呢 ?  謝

rgemhkie 發表於 2013-10-16 13:12
If not use波箱, but use smaller propeller, 效果是否一样呢 ?  謝

樓主, 你尼只係咪雅虎只鹿特單船, 長一米, 如果係, 咁就一定要裝波箱, 有5:1 裝5:1, 冇既裝你現有3:1 都可以, 摩打係 550, 因為尼只拖船有番咁上下大只, 完成後落水都幾重, 所以要用返跟殼既車葉先夠力推, 用細葉只船行得好慢.


電池方面: 樓主可以用鴨記買 12v, 粉電, 容量係 14ah, 因為粉電本身夠重, 可以將船壓水至一定深度, 行起尼就定好多, 否則左遙右擺, 3000mah 車仔電太輕
粉電

                               
登錄/註冊後可看大圖

不過要留意電變拖唔拖到 12v, 係yahoo 有一款合心水的, 又平又好用
http://hk.f1.page.auctions.yahoo ... 13&actsrch=srp3

收到,謝謝大家

rgemhkie 發表於 2013-10-16 13:12
If not use波箱, but use smaller propeller, 效果是否一样呢 ?  謝

NO ONE TEACH ME AR ! PLEASE

rgemhkie 發表於 2013-10-17 00:07
NO ONE TEACH ME AR ! PLEASE

如果唔用波箱,用到嘅葉會好細,咁講法其實好籠統,通常都係要試,
經驗話比我知拖船一定要用波箱,因為直出会唔夠力魔打会好熱D电会冇得好快

Thank you Ar

nice project, very good

rgemhkie 發表於 2013-10-17 00:07
NO ONE TEACH ME AR ! PLEASE

車葉太細, 轉數太高=>
1. 燒杯士/啤令,
2. cavitation大=>efficiency差,

車葉太大, 轉數太慢(Back emf細), 摩打電流太大=>電變, 摩打,插頭, 焊口及導線發熱
=>1. 電路內阻増大=>減efficiency,
2. 電路過熱=>燒電變, 摩打,插頭及導線=>燒船

所以1. 要加減速波箱及用大隻大扭力摩打,
及2. 找出最optimum的組合(車葉大小∕pitch, 摩打, 電變, 電池.........)
仲有, 船是無Brake的(車葉停, 船的慣性繼續向前衝), 船的Brake=倒後, 所以電變最好有後波及cut Brake.

水就吹住o甘多先, 之後就要靠你自己實踐!

joeleung 發表於 2013-10-18 00:18
車葉太細, 轉數太高=>
1. 燒杯士/啤令,
2. cavitation大=>efficiency差,

Thanks Joe for your teaching, very useful.

HKCEE  Physics .......back emf......Lenz Law.........

Anybody knows why there has to be "back emf"?
Hint:  The answer is a very basic physics law.

Why no good if "back emf" is small ? Oh I forgot my A-level phy ? who can share ?

i = (Vbattery - back_emf) / Rmotor

back_emf proportional to motor speed

Larger propeller and/or larger pitch angle ==> more drag ==> slower speed ==> smaller back_emf ==> higher i

P= VI increases ==> battery drain faster ==> someone comes here to complain short battery life