Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: MikeA on August 11, 2011, 12:19:39 pm
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ok now im stuck. I want to use a surface peircing prop but im trying to decide which motor would be better.
either:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270793024308&ssPageName=STRK:MEWAX:IT
or
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130560506212&ssPageName=STRK:MEWAX:IT
or
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=390261363448&ssPageName=STRK:MEWAX:IT
im making a 650mm boat mono hull
what do you all think? iny meny miny mo
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you know what forget that i went for the brushless. i know im gonna regret this {:-{
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No you're not.
You have bought a race tuned McLaren F1 compared to Steptoe's horse and a Ford 100E ........ :-))
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Dead right there :-))
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well its 58mm by 34.5mm motor. ive looked at a lot of brushless boats and they all around the 2200kv range this is 3600 i hope its got enough torque. 58 by 34 seems like its a small motor and i dont know if the diameter includes the cooling jacket. it seems everyone measures there motors differently
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I have that exact same motor and ESC in an MFA Spearfish boat. I use an 11.1v 30c Lipo with it and it's mighty impressive on the water :-))
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i got 2 traxxas 8.4 3000mah batteries will they work with it or will i have problems?
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here is my hull i built today needs a bit more yet though:
(http://s3.postimage.org/4p9t3vk4/DSCI0571.jpg) (http://postimage.org/image/4p9t3vk4/)
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The only problem you'll have is that it'll be a little slow....I think you can go up to 18v with that motor? :-) That would be a 4 cell Lipo or a risky 5 cell 18.5v....Your batteries will power it, but I doubt it'll go much more than a little over scale speed.
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is that with my nimh itl be slow or with either lipos or nimh?
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Your batteries are 8.4v, regardless of what type they are, electric current is electric current. I run 11.1v and my Spearfish puts on a good show although it could go much faster with 14.8v and silly stupid at 18.5v...
You'll soon find out how your boat performs on it's initial trial.
:-))
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cant i join run them in series and get 16.8 or am is it going to starve the motor of amps?
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i am consdering useing lipo's but i know little about them. i need some help with them please.
1, if im to use lipo whats the best way to get 14.8 volt that will fit in my boat. should i run 2 saddle 7.4's or a single 4s battery.
2, i gather i need a low voltage cut off. usually with nimh if the batteries are gettin low the boat slows down and you know to bring it back in. But if lipos just cut off as before it slows down does that mean my boat is stuck out in the middle of the lake? what warning have i got?
3, wont 2 8.4's running 16.8 be faster than a 4s anyway? albeit heavier though
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Hi Mike
You have a PM
Timo2
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you dont suppose u could possible fill in the blanks with the rest do you?
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i am consdering useing lipo's but i know little about them. i need some help with them please.
1, if im to use lipo whats the best way to get 14.8 volt that will fit in my boat. should i run 2 saddle 7.4's or a single 4s battery.
It depends on how much room you have - not a lot go with the 2 x 2S saddle packs in series or a single 4s, if you have plenty of room then you can also saddle up 2 x 4S in parallel for better duration.
2, i gather i need a low voltage cut off. usually with nimh if the batteries are gettin low the boat slows down and you know to bring it back in. But if lipos just cut off as before it slows down does that mean my boat is stuck out in the middle of the lake? what warning have i got?
Most esc's have the facility that when LVC cuts in you can reset the esc, (by going to low throttle), to allow 'main' power back, (at a reduced setting), to recover the model.
[/quote]3, wont 2 8.4's running 16.8 be faster than a 4s anyway? albeit heavier though
Hmmm, a fully charged 4S is at 16.8v and should hold a higher voltage, i.e. over 14.4v, under load better than the 14 cell NiMH pack, which will be starting at around 21v 'hot off the charger' stabilising at around 18-19v about 30 mins after charging, but will drop quicker than the LiPo under load. ** comparing like for like capacity packs **
Mark.
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well my the limitations of the motor is 18v max. now with the consideration of funding im trying to run a surface drive with a solid prop shaft. this will mean that the motor is going to have to be as far forward as possible with propshaft running bang down the centre of the boat. I was thinking instead of using 1 large 4's battery use 2 2's batteries starddling the propshaft linked in series not parralell.
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Sounds like a good plan Mike :-))
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you reckon? i was just looking on net to see if its safe to link lipos in series. i think if i can itl will make the boat more stable and keep cog low.
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Li-Po is fine in series, they are fine in parallel as well, so long as they are the same capacity, "C" rating and make(ideally).
Cheers
Nick
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im looking at batteries right now. got to get a balance charger too all adding up
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Hi mike
Have a look at http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=11060
or
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=6478
Timo2
4 of unit 1 , , 2 of unit 2 in the local club
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what size prop shaft do ppl think i should use? i was thinking a 4mm dog drive theres a good supply or props for that size on giantcod. And other thing can i use a flex drive without the having the buy the expense of a stinger or strut?
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you know ive seen a lot of boats with the batteries one side how do they keep balanced?
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To stop torque roll (Prop to big) & help self right if fitted a flood chamber is fitted.
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got my motor today running 14.8 v lipo on 3600kv motor what size surface peircing prop do i want?
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You will have LOT'S of rev's 53000 (ish) Off load %% I would start with a 35mm and go from there. You might be best on 3s.
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got my motor today running 14.8 v lipo on 3600kv motor what size surface piercing prop do i want?
Hi Mike,
The motor is on the small side for the hull you have in mind; in stead of giving us a choice of three motors in your O.P, you'd better had asked what motor would be suitable...
I don't recommend running that motor on 4S, as 53280 rpm unloaded is way too high and will leave you with a blender in stead of a speedboat. (not to mention the bearings, which will bearly stand such rpm's)
Next to that you've limited yourself to metal props, as the Graupner carbon will simple shatter at these rpm.
Metal props need to be balanced and sharpened, mounting an unbalanced metal prop and 'give it a go' may well rip the drive train out of the hull due to the vibrations.
Don't even try full throttle out of the water!
Frankly, every motor over 2000 - 2200KV on 4S is ludicrous IMHO...
What you need for that size hull is a Ø36 mm motor with 1600 - 2000KV on 4S
Even an outrunner like this would work fine:
http://www.ebay.co.uk/itm/RC-Model-1600-RPM-V-KV-Outrunner-Brushless-Motor-OM140-/390250824488?pt=UK_ToysGames_RadioControlled_JN&hash=item5adcc30328
It allows you to turn workable propsizes from Ø 40 - 45mm and have a controllable fast boat.
Regards, Jan.
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Jan
i was hoping youd speak up soon ive been looking forward to your reply. well first things first SH**! i new buying that motor was a bad idea i even posted im going to regret this, The motor and 60amp speed controllers here now i dont want to change it if i can help it. I actually posted a few weeks ago called a different approach to try and get the grasp of surface drive and noone responded so i took the plunge and decided to pick a motor which seems to be popular.
Its funny you say about it shattering because i hadnt taken that into consideration, I attached my 8.4 nimh to it and put my cut down prop on it (if you remeber from my speed controllers post) span it up unloaded full tilt only briefly mind and watched in awe at its 30000 rpmness!! handnt crossed my mind it might explode and get stuck in my face %% needless to say it was fine and so is my face :-))
the motor is 34.5mmØ and 58mm long. i built the boat allready its 600 long by 160 wide at the transom i cant afford to use a flexi drive and stinger so ive opted for a solid 4 mm propshaft from mmb.
instead of going 2000kv on 4s can i get a similar result with this 3600kv on 2s? according to the maths its 26000rpm unloaded. what size prop do you think i would need for this set up then? what kind of prop speeds should i be looking at?
The 8.4 batterys i have are 2 traxxas 3000mah nimh same as used in traxxas spartan with gold connectors. would they be up to the job in this boat? I noticed on a boat of yours with the solid prop shaft that the battery is on one side on the propshaft how did you over come balance inssues?
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Hi Mike,
Your motor looks similar to this one:
http://www.hobbyhot.com/swanghobby-marine-3600kv-brushless-motor-c-281-p-3-pr-1681.html (or the Turnigy 2845-3600 from HK)
The 'problem' is the Chinese give you the outside diameter, which is measured over the watercooling, while the actual motorcan is only Ø 28 mm, which in turn means a tiny Ø18 - 20 mm rotor inside.
This severely limits your propchoice to a maximum of the Graupner 37,5K, which in surface drive will cause the motor to heat up substantially, as I have experienced while using such a motor in a 50 cm stepped monohull on 2S.
The shattering of carbon props doesn't happen while running dry, the prop shatters on re-entry when the boat jumps small waves at full throttle and the hull gets airborn; the motor will rev to the max briefly and upon hitting the water, you've suddenly lost all drive while the blades will have sheered off the hub...
The limit of 2000KV is a value I find practical to work with for my competition boats, as I can use low budget components (ESC and motor) without burning up stuff (too often).
The revs at the prop are other values from the running practice, too small props with 40.000 rpm only create foam and no propulsion.
If you plan on doing some SAW running, these rpm' apply, but only if you use high quality equipment that's up to the task, not Chinese budget materials.
I've ran the 3600KV motor on 2 and 3S, on 2S the boat is behaving well and handles good, on 3S it's ballistic and a handfull to control.
When running 7 cells NiMH, I have the cells divided in three on the right and four on the left side of the propshaft, the three cells soldered in-line, with the fourth next to the third one.
Mind you, this was for use in a 50 cm hull, in your larger hull, a stick of four should work too.
Regards, Jan.
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after all this im going to go as far as i can with what ive got until i have :
a) more money
b) more experience
until then ill use my 3600kv and my 8.4v nimh. ill play with the balance i can do that bit ok, So do you think a 36-37mm prop will be ok with a surface drive solid propshaft set up?
I also got a water cooling system on the cards so hopefully itl keep motor heat down a little bit. Ill bear in mind that other motor for a later date its in my watch list, although how am i going to cool it with being an outrunner {:-{
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Remember £££s = M.P.H %)
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i had noticed. steep learning curve this speed game, but saying that my first boats going well now, took months to iron out the flaws though. that even hops on the little waves and the revs spike it sounds great. if i can get over 20 mph ill be happy.
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I also got a water cooling system on the cards so hopefully it'll keep motor heat down a little bit. Ill bear in mind that other motor for a later date its in my watch list, although how am i going to cool it with being an outrunner {:-{
Hi Mike,
Watercooling isn't an option on these motors, it's mandatory!
Unless you like smoke on the water....
An outrunner should be chosen with a little power to spare, so it doesn't run (too) hot, the remainder of the heat can be cooled away with a watercooled motormount, either home made or bought.
This is how I do it:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-arpro-700-ep-picture33784-koeling-buitenloper.jpg)
A piece of 6 mm aluminium with holes for the motorshaft/coupler and the fastening bolts in it with a hole Ø 3,2 mm drilled through the top.
Both ends drilled out to Ø4 mm so two pieces of aluminum pipe can be glued in.
Add the silicon tubing and you're done.
The motor in the picture powers a 65 cm polyester hull (the Dragon ARPRO) and turns a 43,5mm prop on 3S, speed in the 25-30 mp/h region (didn't measure it).
Regards, Jan.
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so albeit the motor being a bit small then do you think itl work ok? i think ill start with a 35mm prop then work to a 37mm. i put my 36 to my boat and it looks massive lol
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Hi Mike,
Sure it will work, as long as you don't overprop it.
Depending on how light your hull is you mey either get a decent speed out of it, or be very dissappointed....
Got some pics of your hull?
Regards, Jan.
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(http://s2.postimage.org/1dkjcw5d0/DSCI0674.jpg) (http://postimage.org/image/1dkjcw5d0/)
its 220 grams empty. 400 grams of hardware roughly and a heavy 320 gram battery. i expect the boat fully laiden to be 1kg
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Hi Mike,
On 3S with a 37,5K prop you can expect something like this:
http://www.youtube.com/watch?v=kPQy-umzuR8&feature=related
As your boat doesn't have steps (?) the speed will be a bit less and the handling a bit better.
Regards, Jan.
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no there isnt any steps innit. also it came out shallow V {:-{ ill defintly be ugrading the motor later. ive decided to set my prop 70 mm away from the transom, is that ok? plus the rudder only comes out 55mm will this be a problem or should i extend that?
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Hi Mike,
Next to the prop has more effect counteracting propwalk:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-nood-uit-picture4014-mes-als-roerblad.jpg)
Sideview:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-nood-uit-picture13327-turnfin-reduced.jpg)
Also install the propshaft and motor 3-4 mm offcentre to the right for the same reason, counteracting propwalk.
Regards, Jan.
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:-))
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ive installed my propshaft and did ran it in the test tank today with a 30mm test propeller. stationary the top blade was pretruding 30-40% out of the water. is this right or should it be submerged when the boat is stationary? secondly i ran it and it makes lots of spray but hardly any thrust. is this because the props to small atm or is it because surface drives dont create much bollard pull? I tried the prop submerged and it nearly jumped out the test tank.
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ive installed my propshaft and did ran it in the test tank today with a 30mm test propeller.
1)stationary the top blade was protruding 30-40% out of the water. is this right or should it be submerged when the boat is stationary? 2) secondly i ran it and it makes lots of spray but hardly any thrust. is this because the props to small atm or is it because surface drives don't create much bollard pull?
3)I tried the prop submerged and it nearly jumped out the test tank.
Hi Mike,
1) testing a surface piercing prop stationairy in a tank is pointless, only when the boat jumps on the plane you can judge the propheight and angle
2) My first guess is, the prop is too small, resulting in a blender without too much thrust, go up one size and run the boat again (on a pond),
A surface drive has little bollard pull, as there's only one blade in the water.
When the rudderblade picks up a blade of grass, you'll immediately see the nose go down and the topspeed drop.
3) generally speaking, having a well set-up surface drive running submerged caused the amps to surge and motor and ESC overheating (due to twice as much bladesurface in the water).
As you had a very small prop, no damage was done.
Make sure the boat balances at 28 - 30% of the hull length, measured from the transom.
Regards, Jan.
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well im glad you cleared that up. I was getting rather worried then, i was expecting to have to dig my heals in with the bollard pull test.
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heres a vid of my boat, so far so good as far as im concerned:
http://www.youtube.com/watch?v=MgPKYpQMF_k
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Hi Mike,
The boat runs very nice in the video!
Speed is about what I expected ( a 3S lipo wouldn't hurt...).
Well done.
Regards, Jan.
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thanks dude your help is much appreciated. how fast do you reckon it is then im not sure, the boat looks a lot faster when you see it than it does on video.
I also had an issue with flowing coolant wanter, nothing was coming out the exit port, AT ALL. I made some adjustments and hopefully it will work.
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pompebled have you got a link to that motor and prop shaft set up you have in there got something simaler i want to go brush less on cheers :-))
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what the one in the video?
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ive just bought this charger:
http://www.hobbyking.com/hobbyking/store/__7637__Turnigy_balancer_Charger_2S_3S.html
will it charge a 3s 3300mah lipo? has anyone had any experience with these?
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pompebled have you got a link to that motor and prop shaft set up you have in there got something similar i want to go brush less on cheers :-))
Same question as Mike: which motor do you mean?
@ Mike,
Yes, it'll work, but it will take the best part of four hours to charge a depleted 3300mAh Lipo, I believe these chargers are intended for the smaller parkflyer lipo's.
Needless to say there are faster chargers available for about four times as much:
http://www.hobbyking.com/hobbyking/store/__11060__HobbyKing_ECO6_50W_5A_Balancer_Charger_w_accessories.html
You'll need an 5A powersupply for this one, and you'll be able to charge the Lipo within 45 minutes.
Regards, Jan.
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i will eventually buy that charger but ive got the one lipo on order at the minute. even if i charged the lipo on site im stood around 50 mins unless i have 5 lipos and carry a 30 pound battery. which is a little awkward on a bus. :}
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the set up in this pick bud :-))
Hi Mike,
Watercooling isn't an option on these motors, it's mandatory!
Unless you like smoke on the water....
An outrunner should be chosen with a little power to spare, so it doesn't run (too) hot, the remainder of the heat can be cooled away with a watercooled motormount, either home made or bought.
This is how I do it:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-arpro-700-ep-picture33784-koeling-buitenloper.jpg)
A piece of 6 mm aluminium with holes for the motorshaft/coupler and the fastening bolts in it with a hole Ø 3,2 mm drilled through the top.
Both ends drilled out to Ø4 mm so two pieces of aluminum pipe can be glued in.
Add the silicon tubing and you're done.
The motor in the picture powers a 65 cm polyester hull (the Dragon ARPRO) and turns a 43,5mm prop on 3S, speed in the 25-30 mp/h region (didn't measure it).
Regards, Jan.
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the set up in this pick bud :-))
Hi gwa84 ,
The motor in the picture is the stock motor in the Dragon ARPRO, it's a 3635 1520KV outrunner that will turn a Graupner 45 K prop on 3S witout overheating, the watercooled motormount helps to keep the motor cool.
The motor was sold seperately on this site, but I'm having trouble finding it at the moment:
http://bidproduct.com/part/Product_view_BRUSHLESS%20MOTOR_416.html
An equivalent is this one:
http://www.ebay.com/itm/N3536-B-KV1700-Brushless-motor-Sky-wing-ESC-60A-RC-/330606582345?pt=UK_ToysGames_RadioControlled_JN&hash=item4cf9b01a49
On 3S I can turn the same prop and my boat is even faster...
The compact propshaft eliminates the need to allign the motor to the propshaft, as this is taken care of by the coupling bell.
http://www.hobby-lobby-modellbau.com/onlineshop/index.php/cat/c490_Compakt-Drive-Shaft.html
The shaft in the picture is made by Hopf:
http://www.ebay.de/sch/hopf-fertigungstechnik/m.html?_trksid=p4340.l2562
These are made on demand, as I needed a very long shaft (40 cm) to get the angle as shallow as possible.
Let me know if you need more information.
Regards, Jan.
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i ordered mine from mmb. :-))
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jan can u answer ths for me please :-))
http://www.modelboatmayhem.co.uk/forum/index.php?topic=32602.0
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I just did.
Jan.
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thanks but great help
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I am planning to install a Novak 1600KV inrunner and Novak ESC in my 28.5" Dumas Chris-Craft Barellback boat.
I have two of these motor combos on the shelf so might as well try them out. They do not need water cooling because of the type of motor design.
The motors have motor position sensors for better speed control and the ESC has reverse.
Regards,
Giovanni
(http://i913.photobucket.com/albums/ac335/sunworksco/lnovc3604-1.jpg)
(http://i913.photobucket.com/albums/ac335/sunworksco/3219_goat_1200px-1.jpg)
(http://i913.photobucket.com/albums/ac335/sunworksco/1234-1.jpg)
(http://i913.photobucket.com/albums/ac335/sunworksco/Fd91951.jpg)
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Looks a very interesting setup! O0
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Hi Giovanni,
In a crawler, the motor has some airflow around it, in a closed boat it doesn't, so keep a close eye on the motor temperature.
Unless the motor is completely overkill for the boat- and propsize, I would be carefull relying on the manufacturer's data, as that combo isn't exactly cheap...
Let us know how thing go!
Regards, Jan.
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jan do you think brushed motors like these are fast enough for surface drive?
http://www.ebay.co.uk/itm/220839554929?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648
http://www.ebay.co.uk/itm/260802623592?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648
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Hi Mike,
The second one with 32.000 rpm unloaded certainly has the revs, but both are car motors, intended for use with gearing, meaning torque isn't their strong point, limiting the propsize severely.
In a small light hull both motors should work, the highest revving one is more rigger orientated in my opinion, the closed can may or may not work in a monohull, I'm uncertain, as the unloaded rpm's are not available in the link.
Regards, Jan.
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the first motors discription is the small writing towards the bottom of the post it says:
Ansmann Clash Motor Comparison.
Clash 15, Turns 15, RPM 32,000, Current 16A, Voltage 7.2V
Clash 18, Turns 18, RPM 28,000, Current 12A, Voltage 7.2V
Clash 21, Turns 21, RPM 25,300, Current 9A, Voltage 7.2V
Clash 23, Turns 23, RPM 23,200, Current 16.5A, Voltage 7.2V
Clash 28, Turns 28, RPM 16,600, Current 4.2A, Voltage 7.2V
i thought maybe a 34 - 37.5mm prop might work.
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Hi Mike,
Most car motors don't work well (or long) in boats, when I still used brushed motors in my 50 cm monohulls, the 57 mm long 20 or 21 turn motors could handle a 37,5K for 6 minutes max, and required can and brushtabcooling to survive more than three or four heats of 6 minute racing.
Short can motors don't have the torque required, the lower turn motors only have the revs, but no torque to speak of, related to the use in boats in direct drive.
Get a few and see which one burns quickest...
Regards, Jan.
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Hi Jan,
The geared crawlers actually cause the motor to develop more heat so hopefully the direct motor with no gears will run much cooler.
I have bought the Spektrum telemetry system to check temperature of the motor and battery, also the amp draw of motor.
Here are the components. The really nice feature is that I can plug in a dongle receiver that displays the live data to my iPhone or iPad.
The telemetry sensor station only requires a power source from your any brand existing receiver and sends the data directly from the station to the receiver dongle, since it is a transmitter.
I can add a fan to the ESC which may create enough circulation in the engine bay for cooling.
I'm not going to be racing this boat so maybe the motor will last, especially since I will be monitoring the temps.
Regards,
Giovanni
(http://i913.photobucket.com/albums/ac335/sunworksco/4037_1.jpg)
(http://i913.photobucket.com/albums/ac335/sunworksco/lnovc3028.jpg)
(http://i913.photobucket.com/albums/ac335/sunworksco/Spektrum20TR1000.jpg)
(http://i913.photobucket.com/albums/ac335/sunworksco/SPM9549-450.jpg)
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My experience with Novak Brushless in a boat was one drop of water and poof, no work no more >:-o
Wern't you going to put that Novak system in a submarine at one stage with special programming to slow the motor down {-)
Nick
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Hi Nick,
I have decided to use the eFlite outrunner 245KV motor in my subs.
I just bought this motor and a Castle Hydra ESC to replace the brushed motor in my OTW WTC.
It is for my 32nd Parallel 1/12th scale USS Holland submarine (54" length).
Regards,
Giovanni.