Topic: Swordsman prop shaft (Read 3887 times)

Davegn · « **on:** October 04, 2017, 09:49:56 pm »

Hi,
I'm building a Fairey Swordsman based on a set of Aerokit plans. I got a m4 threaded propeller shaft and i'm hopefully going to try and fit a brushless Turnigy plane motor etc but having a look on fleabay i can't find anything that looks like it'll work.
As i mentioned the shaft has an m4 thread and the motor has a straight shaft (haven't measured the diameter yet) How do i connect the two?
All I can see are universal joints of different sizes with grub screws.
Any help would be greatfully appreciated.

jarvo · « **Reply #1 on:** October 04, 2017, 11:15:39 pm »

HI Dave, there is no problem, you by a brass end M4 thread, a universal joint and a brass end to fit the motor shaft, brass ends into the U/J and fit shaft and motor in near perfect alignment. You do this by locking the U/J and sliding the shaft / motor assembly into a pre prepared slot in the hull, shown on the plans, to lock the U/J, I cut a short piece of 12m copper pipe in half length wise fitted round the U/J with a hose clip to keep it all straight.

Depending on the plan, the hole in the keel will be at to steep an angle, this was designed for an I/C engine, try to lower the angle of the shaft to approximately 20% decide what diamiter prop then allow 10mm clearance from the prop tip to the hull bottom, this will give clearance if you fit a larger prop

A superb place for advice and the bits you will need is Anglian Model Center, Great Yarmouth, the guy who owns the place is a boater so he will direct you, a lot of the stuff you see on Ebay coms from him, trads as AMC.

Hope this gives you a start

Regards

Mark

Davegn · « **Reply #2 on:** October 05, 2017, 06:38:52 am »

Thanks for the reply jarvo. I'm pretty sure I know what you mean and I've just ordered some of the brass coupling inserts things off fleabay and a U/J hopefully they'll fit then I just need a motor mount. I've already fitted the propeller shaft at the angle in the plans. I didn't realise it'd make any difference. It'll just have to do. I will definitely lock the U/J as you describe and I might have to make my own mount and water cooling.No rush. Thankyou for the reply.

canabus · « **Reply #3 on:** October 05, 2017, 09:21:17 am »

Hi Dave

I found some metal uni joints on the Banggood website cheap.
Sizes 4mm to 3.17mm/4mm to 3mm/4mm to 4mm/5mm to 4mm and 5mm to 5mm.
Part No. 87379.
My Swordsman is getting Turnigy 3025-1500kv with a 100A ESC, 2 blade 40mm prop and either a 3S or 4S 5800mah Lipo.

Canabus

imsinking · « **Reply #4 on:** October 05, 2017, 10:00:47 am »

Dave , have a look at my post on modernizing an Aerokits swordsman . . . .
http://www.modelboatmayhem.co.uk/forum/index.php/topic,56327.0.html
This was originally an I/C motor and the shaft angle is as was , the important thing is shaft / motor alignment . . .
I'm new to brushless after a lot of advice I went for an out runner set up & 3s (11.1) LIPO battery , you'll be well pleased with the performance . . . .
Bill

Davegn · « **Reply #5 on:** October 05, 2017, 11:38:25 am »

Hi Bill, I had seen your post but I'm still feeling my way round with this r/c malarkey and wasn't sure what bits you were using to connect everything up. Nice boat mind. Canabus, I've got a Turnigy 2830 1020kv, no esc as yet, well only a couple of small ones from a glider project I've got going that aren't any use. I don't really understand the ins and outs of motor/esc pairing as yet but was going to go for a 90a. I've got a 50a if that's any use. It says max loading 18a, max power 168w on the motor specs, not sure if that's got any bearing on esc choice.
I've also got a slightly bigger motor, a 1040kv but the shaft diameter was 3.75mm that I couldn't find couplings for. This one's 3mm hence the choice. I've also got 3 batteries. A couple of 3s 2200mah 20-30c and a 45-90c 2200 3s. Oh and a charger just not completely confident I know what to do with it all!!

canabus · « **Reply #6 on:** October 05, 2017, 12:36:09 pm »

Hi Dave
looking at the Hobbyking specs of the Turnigy SK3 2830-1020kv the 168 Watts is on 3S Lipo's with an ESC 25A, so the 50A ESC should be OK if it handles 3S.
I suggest for that motor a prop 2 blade 30-32mm.
A few other motors we use in that size boat are the 3639-1100kv, 3648-1450kv these run a 60A ESC and the 3025-1500kv and XK3674-1900kv use 100A ESC.
If you wish to stay with 28mm motors, the B28-57-17L 1700kv and B28-57-15L 1900kv only require a 40A ESC.
Canabus

Davegn · « **Reply #7 on:** October 05, 2017, 12:54:57 pm »

Hi Canbus It's a durafly 50a esc for 2-6 lipo, just saconded it from my glider. I'll order a propeller when I know what I'm doing. How exactly do they fit? My prop shaft is M4 do they screw on or slip on with a locking nut?
When you say "that size of boat" do you think this motor is powerful enough? I did see a video of a Swordsman with an 820kv (I think) motor and it was flying around and the boat didn't seam much smaller than mine, although saying that mine is a hefty beast, definitely not a lightweight.

ChrisF · « **Reply #8 on:** October 05, 2017, 09:06:32 pm »

Hi Dave - good to hear of another Swordsman being built. How far have you got with it?

Did you get the drawings off Ebay with the badly drawn templates or have you managed to get a decent set?

I'm soon to start building one based on the Aerokit plans as well though all I've done so far is draw it and talk about it. No need for you lot to agree with the latter!

Have started to get the materials together and yesterday a very nice Outlander motor was delivered. Having read numerous threads etc. I've decided to go with a bigger, higher torque motor with a 35 or 40mm 3 blade prop. Motor being a Tornado Thumper V3 4250/06 800kv running on a 3S LiPo which should give me pretty good performance.

Chris

Davegn · « **Reply #9 on:** October 05, 2017, 09:54:11 pm »

Hi Chris
I've built pretty much built everything apart from the cockpit floor upto now.
I built a One metre racing yacht from scratch using plans etc off the internet. Took about 6 years, more off than on! I'd build a bit till I didn't understand how to go any further then leave it for a while search the tinternet and then start again usually 12 months later, I ended up joining a model boat club so I could get some feedback and they were well impressed. it turned out gorgeous thanks to a little (quite a lot actually) help from my friends.
I'm a complete novice so end up doing things "my way" and this build is no exception. I loved the look of the Swordsman and Huntsman and I did get a set of plans off fleabay. Now, whether they are good or bad I don't know because they didn't go together brilliantly. I think the problem was possibly more than likely mine but anyway It's gone together. I've laid a lightweight fibreglass cloth and epoxy over the hull and sanded it smooth with wet and dry over the last week or so. I'd put the prop shaft in a while ago. I'm just faffing with the spray strips now and the rudder both of which are a pain, and I'm waiting for the u/j and couplings now that I understand them. I'm building the motor mount as well. Hopefully my motor and esc etc are ok so they can go in before Xmas then I'll be happy. I started building a large glider, joined a flying club and gave that up as a bad job for now!! Flying the damned things isn't as easy as I thought it'd be so the glider's on the back burner and I'm re-purposing bits such as the motor etc for the Swordsman. It might not be as per the plans but it'll turn out ok I hope. I'm not looking forward to making the screen and rails for either end so they might take a while but I don't need them to use the boat. It's all a learning curve.
Dave

ChrisF · « **Reply #10 on:** October 05, 2017, 10:15:13 pm »

This is going to be my first build so I'm even more inexperienced than you!

Sounds as though you are doing alright though. You'll have to post some pictures up. If the plans were the same as the ones I got the "not going together brilliantly" definitely wasn't down to you. The tracing of the templates was absolutely abysmal and not symmetrical and for me are virtually unusable.

I do have a couple of ready built Faireys and a sailing yacht that I used during the "summer". But I really want to get on with building my own.

Chris

ChrisF · « **Reply #11 on:** October 05, 2017, 10:22:23 pm »

Ignore, double posted somehow!

canabus · « **Reply #12 on:** October 06, 2017, 01:01:33 am »

Hi Dave

The 850kv motor maybe a larger diameter one and more powerful.
Generally the prop size about equal to the motor.
My Swordsman is no light weight, so the 3025-1500kv is 1300 watts(about 2 HP).
About the same power as a good IC 10cc motor.
The 3025 was on special at the time and the 3648-1450kv(1600 watts)was $14 AU dearer.
Clubs and forum are a great way of picking up info and asking questions.
I PDF-ed all the Aerokits plans I have swap for, as they are all very old paper ones!!!
So far I have the PT boat, Sea Commander, Sea Queen, Sea Rover, Sea Hornet, Swordsman and the Vosper Crash Tender.
Also a few Vic Smeed plans as well.

Canabus

Davegn · « **Reply #13 on:** October 06, 2017, 12:02:59 pm »

Hi Canabus
Unfortunately I let my club membership lapse last year but as you say these forums are definately the place to be, as soon as this Swordsman is finished I'll rejoin.
I'm not sure I understand these motors yet, I definately don't understand electrics but what figures on a motor tell you the power ? (I take that as meaning torque) I know the kv value relates to rpm.

Dave

Davegn · « **Reply #14 on:** October 06, 2017, 12:45:32 pm »

My boat. Spray strips today hopefully.

canabus · « **Reply #15 on:** October 06, 2017, 12:54:23 pm »

Hi Dave
The WATTS is the power and about 750 Watts equals ONE HORSE POWER.
The kv is the number of rpm per volt.
So 1000kv on 2S Lipo(7.2 volts) is 7200 rpm, on 3S is 11100 rpm and on 4S is 14800 rpm.
This is the unloaded rpm, but, the brushless motors do not drop the rpm too much with the right prop.

Canabus

Davegn · « **Reply #16 on:** October 06, 2017, 08:42:12 pm »

So according to the specs this motor is 168w that's just over 1/4 hp and on 3s is 11,322rpm. I've no idea what that equates to on the water we'll have to see but that's something else I've learned. I'd best make this motor easily removeable!!
Thanks Canabus

Davegn · « **Reply #17 on:** October 08, 2017, 01:42:29 pm »

Canabus,
Sorry to keep on but are you better with high rpm or high watts? I've just found lurking in my glider a 960kv motor with 510w as opposed to 1020kv with 168w

ChrisF · « **Reply #18 on:** October 08, 2017, 02:42:12 pm »

Hopefully the latter! High watts that is.

I've gone the route of a bigger motor to which I will add a 100 amp ESC so that nothing has to work hard and I won't have to bother with any cooling.

I don't intend to be ripping around the lake anyway.

Chris

Davegn · « **Reply #19 on:** October 08, 2017, 04:22:42 pm »

960kv it is then. I'll get a bigger, esc mine's only a 50a. I'm just finishing the hull, that'll take me a couple of weeks then I can concentrate on the innards.

ChrisF · « **Reply #20 on:** October 08, 2017, 05:16:59 pm »

Ì don't have any experience of which is best so I'd see what Canabus says.

Davegn · « **Reply #21 on:** October 08, 2017, 07:05:45 pm »

I understand. lower kv and higher watts is what I've gathered upto now, will just have to see. Just a bit confusing for a newbie.

Davegn · « **Reply #22 on:** October 25, 2017, 09:21:49 am »

I've gone with the 960kv, 510w glider motor as it's an Inrunner as well. Nearly finished the hull, just needs paint. I went for enamel from halfords on my yacht so I'll do that again. I've made a mount and positioned the motor as good as I can. Made a battery box and positioned the esc, bit the bullet and fitted the rudder and servo, just a bit of tweaking and I should be able to test it on the water soon ( just got to re-join the local boat club) Not sure about water cooling yet but I'll have to see. I've got an intake and outlet ready to fit.
Thanks everyone for the replies, helped me no end.

ChrisF · « **Reply #23 on:** October 25, 2017, 01:52:48 pm »

See how it goes but size for size inrunners aren't as torquey as outrunners and I guess are generally used for higher revving applications.

I've ordered some more parts i.e. the motor mount, prop shaft and couplings so have most of what I want now. As per another thread I've nearly got my work area sorted so will be starting building soon.

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Author Topic: Swordsman prop shaft (Read 3887 times)