|||
Current Website Support
70
Contributors
6
Subscribers
You are Not Registered
Donate for your silver medal ๐Ÿ…
ยฃ10
ยฃ15
ยฃ25
ยฃ50
Subscribe for your gold medal ๐Ÿ…
ยฃ1
ยฃ3
ยฃ5
ยฃ10
You Will Be Helping Towards:

  • Domain Fees
  • Security Certificates
  • iOS & Android App Fees
  • Website Hosting
  • Fast Servers
  • Data Backups
  • Upkeep & Maintenance
  • Administration Costs

    Without your support the website wouldn't be what it is today.

    Please consider donating towards these fees to help keep us afloat.

    Read more

    All donations are securely managed through PayPal. Amounts donated are not published online.

    Many thanks for your kind support
  • Join Us On Social Media!
    Model Boats Website
    Model Boats Website
    Home
    Forum
    Build Blogs
    Media Gallery
    Boat Clubs & Lakes
    Events
    Boat Harbour
    How-To Articles
    Plans & Docs
    Useful Links
    6

















    Followers
    Brushless motors
    by MouldBuilder ๐Ÿ‡ฌ๐Ÿ‡ง ( Lieutenant Commander)
    ๐Ÿ“ฃ










    Click To
    Follow
    25 Posts 24 Replies 6 Photos 46 Likes
    ( Newest Posts Shown First )
    RHBaker
    Sub-Lieutenant
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡จ๐Ÿ‡ฆ Canada
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Following the improvement gained on my RTTL installation, decided to do the same to my Brave Borderer - again on the bench.
    Removing the "Brake" feature on Fwds/ Rev definitely smooths the transition and gives better control.
    Looking forward to trying on the water where the resistance should give a further improvement. Afraid my access priviledges to our indoor test tank have been restricted!
    1
    RHBaker
    Sub-Lieutenant
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡จ๐Ÿ‡ฆ Canada
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Omitted to mention after RTTL, on the bench!
    RHBaker
    Sub-Lieutenant
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡จ๐Ÿ‡ฆ Canada
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Doug, one of your earlier messages mentioned programming the ESC Fwd/Rev to not include the brake function.
    This is contrary to advise had previously been given. However, intended to test properly once our local ponds reopen as could help the controlability of brushless powered models.
    At something of a loose end due to these virus strictures, decided to test it on my RTTL hull.
    It does "soften" the Fwd/Rev action, making the motor more tractable.
    Will reprogram my Brave shortly but am confident a similar improvement can be achieved.
    2
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    "I have learnt a lot about both brushed and brushless motors.๐Ÿ‘๐Ÿ˜€"
    Glad to help Peter.
    We all had to learn when brushless started to take over the market.
    Although their advance seems recently to have stalled a bit wrt boats๐Ÿ˜Š
    I went round this learning loop a couple of years ago, prompted by some excellent starter advice from Canabus in Tasmania!!
    For the fly boys of course they are the Bog's Dollox, as Steve so eloquently describes such superior qualities๐Ÿ˜ฎ
    For us boaties brushed still have a place in large high displacement hull scale ships. And subs, which don't need to be sprinters, although my Type 1A U25 IS with two 385s on 12V ๐Ÿ˜
    For the faster Deep V type planing hulls brushless (plus Lipo for the not faint of heart!) must be the way to go.
    Happy building and sailing folks, whoever your motor God is๐Ÿ˜‰
    Stay safe and be alert - the world needs Lerts now more than ever!!
    Cheers, Doug ๐Ÿ˜Ž
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    RHBaker
    Sub-Lieutenant
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡จ๐Ÿ‡ฆ Canada
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Thanks Doug, been watching this correspondence with interest.
    Will now reprogram to eliminate the brake function, had once been advised to use it. After the ice goes and will try it and let you know the effect.
    Had already arrived at the "soft start" setting by trial and error. It was an improvement, but the brushless motors are still erratic on part throttle..
    Have toyed with the idea of changing out a brushed for a brushless to see the effect on performance. Rather as you have done.
    I have this fetish about building accurately, so could not even dream of changing out propellers!
    Theoretically brushless should give a lower power consumption than a similar brushed in the same vessel. Same speed and prop.
    Unfortunately the temptation is to use the increased performance and power consumption goes up.
    I have an inline voltage/Current/wattmeter and with a 550 size brushed motor, current consumption is usually under 5 Amps.
    Using 2800 and 1100 kv brushless outrunners 20-30 Amps on a 3S cell is fairly normal. Periodically a 30A fuse may blow, but these are very conservative as the ESCs are 50A.
    My Brave Borderer goes well with 2 x brushless, the high power consumption is worth it for the exhilaration!
    3
    MouldBuilder
    Lieutenant Commander
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 8 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Thanks for all of your help. I have learnt a lot about both brushed and brushless motors.๐Ÿ‘๐Ÿ˜€
    2
    I promise I will finish a boat project before I start another......Maybe.
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    PS Peter,
    "I reckon that 1000kV and a 40mm prop are probably at the very top end of the useable combination range."
    Apropo combination_
    If your motors get too hot to touch and draw a lot of amps (which I don't really expect) then you have two choices-
    1 Reduce the size of the prop.
    Fitting a prop with a lower pitch might help but not as much as reducing the prop diameter.
    NOTE to our prop aficionados; I'm not absolutely certain about the pitch, contributions welcome!๐Ÿ‘
    My reasoning being that lower pitch means that the prop has less work to do per rev so allowing it to rev more freely and putting less strain on the motor = less current and heat! Corrections welcome if necessary. I.e. if someone knows better and has the math to prove it!๐Ÿ˜‰

    2 Fitting a beefier motor;
    i.e. a fatter motor with more torque and probably a little lower kV.
    Props are cheaper ๐Ÿ˜‰
    Cheers Doug๐Ÿ˜Ž
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Hi Peter,
    There's lots more math and tech behind what I wrote but I tried to boil it down to the essentials.
    Around 8kg was about what I'd figured for the all up deadweight๐Ÿ‘
    So I reckon that 1000kV and a 40mm prop are probably at the very top end of the useable combination range.
    Attached is the spec table for the Graupner brushed Speed motors.
    Looks like they suggest the model 3302, Speed 600 BB Turbo (Vroom vroom Maisie!) nominal 12V. That's listed at 17500 rpm at nominal 12volts off load. 17.1A max drain on load๐Ÿ˜ฎ Max efficiency probably around 60% or less.

    A 1000kV brushless will have an efficiency more like 80%, thus draw less current for similar performance as the 600 but still have power in reserve, do 11100 rpm or more off load on a 3S Lipo, and produce more torque than the 600.๐Ÿ˜Š More torque means you can swing a larger prop.
    So my bet is that underwater, i.e. on load, the brushless will produce more torque, thus revs and thrust, than the 600.
    Don't have a formula for drop in revs On Load I'm afraid๐Ÿค”
    Two of 'em acting together should provide more than enough Oomph.
    Nough said?๐Ÿ˜‰
    Cheers, Doug ๐Ÿ˜Ž
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    MouldBuilder
    Lieutenant Commander
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 8 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Thanks Doug.
    A very good answer to a question I dared not to ask as I thought it wold be a complex answer. Now I know what the numbers mean.
    If I were to go the brushed route, they would run on 3s LiPo`s. 12v version.
    The finished boat has a displacement of 8kg. Does this affect your kv judgement.
    40mm props are supplied.
    Thanks.
    Peter.๐Ÿ‘
    2
    I promise I will finish a boat project before I start another......Maybe.
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushless motors
    Flag
    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 2 hours ago
    ๐Ÿ˜Š View Profile
    ๐Ÿ’ฌ Send PM
    Hi Peter
    "suggested 600 motors"
    Hmm! That depends on WHICH Speed 600 was suggested!
    There are several versions, from 7.2 to 12V and off load RPM from 14300 to 21500๐Ÿ˜ฎ So which spec to use as a basis for choice of a brushless???

    My choice would be a pair of 750 to 1000kV brushless.
    Prop size significantly affects current drain and speed.
    Often a bigger prop simply sucks more current with no performance gain.
    Maybe the contrary in fact.
    Size of brushless motor:-
    They are quoted as xxyy, in my Sea Scout 2830 (Outrunner by 'Propdrive' HobbyKing). That means 28mm diameter and 30mm stator length.
    Relevance?
    The larger the diameter or the longer the stator size the greater the torque but usually lower kV. (Revs per Volt OFF LOAD)
    So for tug pulling perhaps a big fat, long outrunner with kV 250 or so.
    For max speed a short, slim motor for hi revs for the competition racers.

    I reckon for your Lifeboat a decent compromise between start torque (to overcome the boats inertia) and a good speed would be a pair of something similar to the 2830 1000kV I used in my Sea Scout.
    I only had one in a 28", 2kg boat, your boat is bigger 'n 'eavier so two should do the job nicely๐Ÿ˜Š
    Also recommend a pair of the Quicrun ESCs to drive them. Type Hobbywing Quicrun 16BL30 or current equivalent. They're good for 30A but I don't think the motors I suggest will ever draw more than 10A in your boat, WITH THE RIGHT PROP SIZE! Prob. 35 - 40mm MAX.
    Get the Programming card to go with it as that easily enables you to switch off the irritating Brake function and to set the Start to Soft, which eliminates the problems Rowen had with 'jump starts' and slow speed manoeuvres.
    I run my Sea Scout on a 4Ah 3S (11.1V Nom) battery which gives me well over an hour runtime and great performance. See my Boat Harbour, Blog and Video Gallery for trials videos!
    If you can fit one similar battery per motor I think you'll be a very happy sailor๐Ÿ˜Š๐Ÿ˜Š You can always throttle back!๐Ÿ˜ฎโšก๐Ÿ˜ญ
    Enough ramblin'๐Ÿ˜ฎ Hope this helps more than confuses ๐Ÿ˜‰
    Pics show my Sea Scout 'Engine Compartment' and differences between old motor and prop and the new๐Ÿ˜‰
    Bon chance mon ami๐Ÿ‘
    Cheers, Doug ๐Ÿ˜Ž
    3
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    Show 15 More Posts



    About This Website
    Terms of Service
    Privacy Policy
    Cookies used in this website are gluten free, wheat free and dairy free. By using this website you agree to our use of cookies. More Info