Slo mo Shun

[Phil Winks 1Participant @philwinks1]

That lot looks the business Bob! I just love it when the postie brings goodies, just a big kid at heart lol. The cooling fan seems a good idea although it might mean making some of your psuedo vents functionall. one of my 550 motors has one built in so guess its not a bad idea

[michael kemishParticipant @michaelkemish72883]

Hi Bob, I’ve been following the thread for yonks.

Regarging the water cooling, why not try longdtiudinal(?) tubing. Don’t wrap the water cooling round and round, but make them go end to end, then bent 180 deg, ad infinitum, so it’s  a bit like the heating element in an electric hot water system.

Encase the motors in the tubing, and use cable ties so that the tubing is in good tight contact with the motor casing(for best heat transfer)

If this a bit confusing, I can try and post some sort of diagram

Cheers,

Mick

   

 

[Bob Abell 2Participant @bobabell2]

Thank you, Michael

 

I do understand what your saying and it`s a good idea.

 

The only snag is that it may look very untidy……..compared to a nice little ali fan screwed to the end of the coupling?

 

Thanks for our suggestion………Keeping posting your comments….Always welcome

 

 

Bob

[Paul TParticipant @pault84577]

Bob

 

Try using a computer fan……

 

 
they are very good at shifting air and dont draw much power, the barrel back has two that help push cooling air around the IC engine.

 

Paul

[Bob Abell 2Participant @bobabell2]

Hello Paul…….Welcome back, old chap

 

I like these pc fans, but I don`t want to get involved with tapping off the power to run them and all the extra wiring

 

I like the coupling fan idea…….the couplings have plenty of mass to screw a little fan on….about 60mm dia………..and I can easily make them.

 

How is your Barrelback these days?…….You sound as though you`ve not been completely idle?

 

Bob

[ashley needhamParticipant @ashleyneedham69188]

Bob. The props and shafts are the business !!  i am sure your boat will motor very satisfactorily with that sort of power . I should think you will having the most fun a man can have with his trousers on. Shame the motors look so “agricultural”, lacking vents fans and fancy cutouts/alloy bits. But we shouldnt judge the quality from the plain exterior! Are you still going to use gell cells or NiMh batteries??

 

I have put fans on couplings before now, just to stir the air a bit. However, some cooling fins on the motors would make this twice as effective, and also you need to shift the air into/out of the boat or the inside just becomes like an oven. Could paint the casings matt black?

 

A few water cooling coils would be the best idea, fitted now, before you finish all the works. i wouldnt worry about weed blockage, you should be able to see the water coming out of the pipes and notice a blockage long before melt down, if indeed they get that warm anyway. It may be that those little computer fans actually move the air better, and at less power that the alternative, but its hard to judge.

 

Paul…long time no post !  

 

Ashley

[Bob Abell 2Participant @bobabell2]

Morning Ashley

 

These prop shafts are really impressive….quite heavy too!

 

I`m thinking about shortening them, just to save weight….but the question is….Where is the point of balance?

 

Geeezzzz…….there`s no end to theoretical questions regarding this build!

 

With a model aircraft, the COG was easy, but with a boat…that`s another story.

 

So be a good chap, Ash, and check with your speedboat flotilla……..rest the hull on a strip of thin wood and give us your opinion, please……… this could be important in planning the heavy battery positions etc?

 

Bob

 

 

[Bob Abell 2Participant @bobabell2]

I`m using a temporary template, bolted to the hull, to align the propshafts and keep them in place, while messing about at the other end.

It`s quite a tricky job, setting the propshafts, due to access space being limited at the motor area

 

Jolly good fun, all the same………Bob

[michael kemishParticipant @michaelkemish72883]

Hi Bob,

2 things

 1)Air cooling the motors is good. You need air ingress and air outgress(?). Water can get in through the air ingress vents, but, because water is heavier than air, it won’t get out of a vent above waterline.

2) On my Matilda, I put the propshafts in at about the same stage as you are doing. The A frames were a pain in the ###!. I’ll watch with bated breath to see how yours go! Most of the other people tend to put the props etc into place quite early on in the build.(There must be a reason!)

Mick

 

 

[Bob Abell 2Participant @bobabell2]

Hello Mick

 

Nice to know that the fan idea has been approved!

 

For the “A” frames…… I`m thinking of a simple triangular fillet glued between the propshaft and hull.

 

I`d like to see a picture of your A frame construction if possible please?

 

 

Bob

[michael kemishParticipant @michaelkemish72883]

I’ll try.

Mick

 

[Bob Abell 2Participant @bobabell2]

Here we go!……With the propshafts accurately located fore and aft………I can epoxy them in now……….Shortly

[Phil Winks 1Participant @philwinks1]

!st things 1st welcome Back Paul I trust things are as well as can be with you. on the “A” frame question Bob I’d suggest 2 things either a pair of brass sheet affairs wrapped around around the tubes and soldered to it and epoxied to the hull or as I did on the Barrell back  a simple ply fillet between the tubes and the hull forming a skeg like fin.

 

Just a thought

[Bob Abell 2Participant @bobabell2]

Thank you Phil

 

I was going to simply glue a ply fillet between the Propshaft and hull, but an ali “A” frame may look more technical and more businesslike?

 

Paul doesn`t hang about these days………Doctors orders, no doubt

 

 

Bob

[Dave MilbournParticipant @davemilbourn48782]

Bob

Your simple fillet won’t handle any sideways vibration forces while an A-Frame would. I’ve recently come across Prop Shop’s new website and didn’t know until then that ‘iggins makes A-frames. Have a shufti here if you’re curious:

http://www.prop-shop.co.uk/index.php?id=39&section=services&sub_section=products&product_type=39

 Ref cooling; it’s been proven that a water-coil works while fans haven’t been tried on these motors. Your call. Me? Bent pipe every time!

DM

[Bob Abell 2Participant @bobabell2]

Thanks for the info, Dave…….I`ll make A frames when I can find some thick ali.

 

I gonna try the fans first……..Bob

[ashley needhamParticipant @ashleyneedham69188]

Bob, fitting a water scoop may be i bit tricky with your extended rudder mounts, or is there more room than the photos suggest?? You may have some nasty cheap silicone pipe to hide as well….ah…unless the outside bit is copper……

 

Remind me of the prop size to prevent me having to scroll though 600 posts, thanks

 

I will do the balancing thing on me speedboats, but yours is a hydro or whatever and the balance point for these would be different, as , dont they go along parallel to the water once up on the plane? Mine are sitting on their tails at speed, or at least, the Fantome actually doesn’t quite go that fast…..

 Ashley

 

[Bob Abell 2Participant @bobabell2]

Ashley

 

It is a bit tiresome, going back in time on this marathon thread.

 

The prop size is 54 dia X  77 pitch with space for at least a 60 if need be.

 

Yea….Those plastic set me thinking about an alternative….hence the fan idea

 

I`m going to keep the balance central at the moment and use the four batteries as floating ballast….good…eh?

 

Bob

[Paul TParticipant @pault84577]

Good Morning Bob

 

You are right about doctors orders…..…..still never mind.

 

The barrel back sailed for the first time on boxing day (a day long planned for) and after a little bit of ballast trimming had a few bursts of speed along the Bridgewater canal.

 

The cooling fans worked very well in pushing cool air around the engine and even after a quarter hour of heavy use the engine temp was still within its operating limits, there was a little bit more smoke from the exhaust than normal due to having the mix on the rich side for running in however the oil traps on the exhaust worked well and stopped any unburnt oil reaching the water.

 

Sorry no photos and I dont plan on sailing her again until summer.

 

Paul

[Bob Abell 2Participant @bobabell2]

Good morning, Paul

 

The fact that you were well enough to sail your boat on Boxing Day is really good news to us all.

So your dream came true…….An IC powered Barrelback……Well done!

 

How was it for stability and point of balance etc…….No need to reply straight away, if you don`t feel up to it, Matey

 

Where did the warm air vent itself?……..I`m going to need to add some good air vents on Slo Mo somewhere

 

I`m busy installing the motor base at the mo………it`s being screwed in, in case there`s a motor change in the future

 

All the best, Paul………………..Bob

[Paul TParticipant @pault84577]

Bob

 

The warm air is vented behind the rear seat, the boat ran straight and true and went onto the plane with no problem,

 

Paul

[Bob Abell 2Participant @bobabell2]

Thanks for the info, Paul

 

The crunch question…………..What is the power of your IC engine, in Watts or HP?

 

Bob

[Paul TParticipant @pault84577]

The makers spec puts the power at 1.6hp, at some point I will do a bollard test and see what the pulling power is.

[Bob Abell 2Participant @bobabell2]

Here yer go, Dave

 

For scale, the dimension at the top is 725 mm

 

Hope you can read it………For some reason, on this PC the printer won`t work

 

Bob

[Bob Abell 2Participant @bobabell2]

Work in progess……

 

Bit the bullet and finally epoxied the prop tubes in place and fitted the “A”  frames

 

Bob

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