Brutus

[Paul TParticipant @pault84577]

Bob

Re the rear vent: Get hold of some fine mesh (like a net curtain) spray it black and stick it to the inner face of the cabin covering the vent hole, it will create the same recessed effect as the roller door.

Re the forward intake: The tin lid looks like the worst ever afterthought as would any scoop, box or protrusion through the roof. The whole point of this design is clean lines and flat smooth surfaces so anything sticking out of the deck or roof will ruin the effect.

I would suggest that you don't do any more work on the cabin until I have come up with another solution to the cooling problem.

Paul

[Paul TParticipant @pault84577]

Bob

I have changed the route of the air intake and now the opening is above the exhaust port on the rear cabin wall.

 

Paul

Edited By Paul T on 11/02/2014 19:21:38

[Bob Abell 2Participant @bobabell2]

That`s ok

How wide is it?……100mm?

Bob

PS…We`ve had 256 views since 6.00 this morning…….and yet, nobody will say owt!……..Pathetic!

[Colin BishopModerator @colinbishop34627]

We are all watching in fascinated anticipation as to how the ventilation problem will be resolved Bob. Most of us would probably just drill a big hole in the top.

However I must confess to some puzzlement as to why the motors/speed controllers will need cooling. Surely this implies that a lot of energy is simply being wasted which is very inefficient. All that heat has to come from the battery.

Surely the engineering issue is to convert the energy into propulsive force rather than heat by achieving the optimum motor/prop combination.

Colin

[Bob Abell 2Participant @bobabell2]

Hello Colin

I was surprised by the fans and vents myself!

Paul says the Drawing Office has contacted the suppliers and has been given the facts on heat generation, so we can't argue with that!

I'm also surprised that some of the knowledgeable readers, haven't mentioned it too?

But it is common for some motors and ESC's to have cooling pipes?

Paul loves calculations and technical problems………It keeps him occupied and it does make the model more mysterious and interesting though?

We are having a great time , working as a team……Two heads are better than one, so they say

Rear Admiral Bob on the shop floor

[Bob Abell 2Participant @bobabell2]

Paul

While you're having your beauty sleep, I've made a balsa wood rectangular tube, 16 x 100 section

Can put it anywhere in the top cabin area, so it will miss the obstructions

Might be a nice idea to incline it downwards to the hull area?

All clever stuff, this

Bob

[Paul TParticipant @pault84577]

Bob

The 16 x 100 box section sounds just right but it needs to remain flat and level until it reached the plenum and then it can be angled downwards. Its important that the box section inlet and plenum follow the design on the drawing as the air has to be delivered to the intake side of the main cooling fans.

Paul

[ashley needhamParticipant @ashleyneedham69188]

The ESC airflow is shown as up, whereas I think the little fan above the ESC blows down….just a thought.

Colin. No way to cool an outrunner properly as the outer casing revolves. It is unlikely to get hot, whereas the esc heatsinks are not that big and so require cooling. Anything handling a reasonable Amperage will get warm/hot.

I once thought of running the rubber motors in my Ashleyboat2 in water tubes, to prevent them melting, such was the latent power at my disposal.

I also think, as I am wont to do, that you only need some air throughput and not necessarily a gale, so I would not be too worried about a vast volume of air flowing through the hull, just "enough"….

Ashley

[Paul TParticipant @pault84577]

Ashley

The airflow arrows indicate the primary intake and exhaust route, the ESCs have been positioned within this airflow so it doesn't matter which way their little fans blow and don't worry about the volume of air passing through the boat as the pair of case fans provide the correct quantity without placing to much drain on the batteries.

Just been watching the weather reports…..Are you feet wet?

Paul

[Trevor HollowayParticipant @trevorholloway99134]

Have been following this one from the begining and am intersted in the unorthodox design, build methods, technical problems (and solutions) and now the various airflow issues but have not joined in before as sometimes it is more interesting to overhear the conversations between the various departments than "butt in".

[Bob Abell 2Participant @bobabell2]

You are very welcome to join in, Trevor

We are delighted that you are enjoying the thread

Paul

Got the vents sorted now

We may need a means of fastening the cabin down……..A toggle would be nice

Bob

[Trevor HollowayParticipant @trevorholloway99134]

OK, hows about using magnets, as there would be no external protrusions.

[Paul TParticipant @pault84577]

Bob

Sorry to say this but the mesh on the vents is to large and the handle on the roller door doesn't look right, in common with all roller type desks it should have a very slim strip of timber across the very bottom which is used as a handle. Remember the design criteria The whole point of this design is clean lines and flat smooth surfaces so anything sticking out of the deck or roof will ruin the effect.

The cabin is supposed to be a tight friction fit against the coaming and so 'toggles' should not be used, at the very most you could use magnetic catches as Trevor suggests.

Trevor

Please feel free to pitch in at any time.

Paul

 

Edited By Paul T on 12/02/2014 16:12:11

[Bob Abell 2Participant @bobabell2]

Paul

The mesh panels are only pushed in, so they are easily changed.

I'll have a look round for something else then. How about the fine mesh found in funnels or sieves?

The handle can also be replaced

The fans arrived today

Bob

[HowardParticipant @howard79726]

Paul & Bob

As one of the 250 plus viewing this thread I must say how much I am enjoying it, and being a relative newcomer to the hobby I find it useful to watch and learn while more experienced hands and heads deal with the various technical issues, so thank you gentlemen.

The cooling fan topic interests me because drawings for my next project, a Halvorsen 38' seaplane tender, show an option for two cooling fans. What would be the preferred way of connecting these; directly to the supplies from the motor batteries, switched or via a relay, or from a separate battery, although I don't suppose they draw much current?

Again, thanks for the insight into your Brutus project and keep up the good work!

Howard

[Bob Abell 2Participant @bobabell2]

Hello Howard

A warm welcome to our forum, we are very pleased to hear that you are enjoying our build thread

Your question about the power source for the cooling fans is very relevant and it's encouraging to note that cooling fans were called for, on your model, in the first place!

I've been wondering that myself. Until someone jumps in with a better suggestion, I would use a separate battery source and switch. If we forget to switch on, before a sail, the motors will cutout safely….I hope

What does Dr No say on this subject?

Bob

[Bob Abell 2Participant @bobabell2]

More work in progress…..All great fun

Mounted the cooling fans is place with the top vent box in it`s simulated position

Cold air enters from the stern end and falls behind the fans which in turn, blow cool air over the motors and esc`s

All clever stuff…eh?

Bob

[Paul TParticipant @pault84577]

Bob & Howard

Depending upon the voltage and current draw the cooling fans could be linked into the main power source at the master switch, however given that we don't know either the voltage or current draw it might be best to establish a separate supply and switch and let the cooling motors run independently.

I would imagine that a electrical wizard like DM would wire in a thermostatic switch and only have the cooling fans running when necessary but for myself, being an electronic numpty, I would rather switch them on when I started sailing and leave them running until I pulled the boat out of the water. With this in mind the prospect of having the cooling fans running all day would prompt me to run a bench test on battery life as I wouldn't want the cooling system packing up mid sail.

On a wider note perhaps I should be nominating positions for cooling fans and ducting on all of my designs…….after all Bob is not the only person to use these types of ESCs.

Bob the inlet duct and plenum look superb and yes smaller mesh such as sieve (i.e 1>2mm hole) would be ideal.

Paul

[ashley needhamParticipant @ashleyneedham69188]

Bob/Paul. Those fans need to be on display, they are so cool. Cant they be used to add to the overall propulsion?? (dont answer that)

Ashley

[Bob Abell 2Participant @bobabell2]

Thanks Ashley

They look the part alright, in fact, all the boat looks snazzie!…..Not forgetting Paul`s Hi Tech cooling system!

Just starting to get the propshafts and rudder mechanism in, before the stern gets glued in place

I keep looking at the Brushless motors and then the ECS`s every now and then and the mysterious wires all over the place. I know it will get sorted shortly, but not looking forward to it, with a brave heart!

The fear of the unknown, you see!

Bob

[ashley needhamParticipant @ashleyneedham69188]

Bob. Brushless motors are just motors, there are three wires to them not two. If they run the wrong way round you reverse any two of the wires, doesnt matter which ones . There is nothing to it at all.

There will be no issue with the propulsion, other than the lack of power/too much power/props too small/large and the usual.

Unfortunately you are not building to Dr No`s (Paul,is this phrase annoying??) 600 motor spec and so anything can happen…..

Ashley

[Bob Abell 2Participant @bobabell2]

Thank you, Ashley

Question…..Why can't a normal motor with a rotor be Brushless?

Just a thought

Bob

[ashley needhamParticipant @ashleyneedham69188]

Bob. With a brushed motor, the permanent magnets are on the outside casing, and the electromagnets are on the inside. As this rotor goes round, so the electromagnets have to be fed via contacts, and so we have brushes.

On a brushless motor, this is, as a simplification, the other way round, and the rotating bit has the permanent magnets (dont need to be fed electricity) and the electromagnets are on the static casing. This means there is no need to have brushes, wire connections can be permanent. They operate in a different manner as well, but this is taken care of by the ESC, which is why you have to have a brushless ESC for a brushless motor.

Ashley (I think thats about right)

[Bob Abell 2Participant @bobabell2]

Thank you, Ashley

Why can`t the permanent magnets be on the rotor?

Bob

[Keith LongParticipant @keithlong89920]

Posted by Bob Abell on 14/02/2014 08:19:40:

Why can`t the permanent magnets be on the rotor?

Bob they can be, suggest you "Google" "brushless inrunner" or "brushless inrunner vs outrunner".

Keith

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