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[John W E]

hi there


according to the book Allied Coastal forces written by Mr John Lambert and Mr Al Ross - a line drawing in the book shows the side view and top view and it is described as an engine room hatch vent.


I am surprised Stan the Man hasn't picked up on this thread.  Stan built a cracking model of this subject - if I can find some pictures we can put some on.   I used his model as a reference for myself, when I built a stand off model using a plan drawn by GG.


MODEL ELCO 80 MADE FROM FREE PLAN (modelboatmayhem.co.uk)


John

[Allen A]

Looking at the last image from the link from Dodgy Geezer above ..   http://www.pt103.com/images/Italeri_Page_Dwg_Engine_Hatchway_PT187_196__314_367.jpg  ... think you are right, I overlooked the obvious in trying to find an answer I think ??

[Allen A]

Thanks for that link John .. yes .. what a cracking model, sort of detail I would aspire too, problem being I don't have the skill, as I like to say, I do the best I can with what I haven't got .. 

[Allen A]

Sorry to be a pain gents .. wondering if I can come back to the No 2 boat and if there's any thoughts or suggestions about how it goes forward when in reverse command despite the motors reversing as they should .. pics attached of the prop rudder layout if they help .. beats the heck out of me ..  ??

[John W E]

Hi there Allen


Looking at your picture of the boat's internals - speed controller etc. - and googling the make of your speed controller and reading up on the specs and setup, I can see that on the instructions there should be 2 jumper clips - 1 for lipo battery etc., and the other 1 is for the forward brake only backward brake only and then the 3rd is for forwards and backwards with brake,


I have noticed in your photograph that you are only showing 1 jumper lead and that is for the type of battery you have and not for the mode for the speed controller - Could this be your problem of not gaining reverse?   or, is is set in the wrong mode somewhere when set up?


John

[John W E]

 

[Allen A]

Hi John .. yes aware of the jumper thing as I took the ESC back to the shop to point out it wasn't there, however they told me it wasn't necessary as in the instructions for straight forward fwd/rev operation the diagram shows no jumper is needed .. ??   pic attached .. also that I maybe didn't set it up right has also crossed my mind ?

The thing is and its a big BUT ... as I say when on the stand and with fwd command on the TX the props spin anti clockwise, and with reverse command from the TX  the props spin clockwise ie; in the opposite direction, essentially working as it should .. right ..  yet when in the water and in reverse command on the TX it still moves fwd which makes me wonder about prop size or shape and if they could be too close to the rudders as I cant see any reason why that should happen .. ??

Just tried it on the stand again and the props definitely move in two different directions when fwd and reverse commands applied on the TX, cant figure it out at all !!

[John W E]

Hi there Allen


I still have concerns about your speed controller having just one jumper lead.    I have basically the same one, although it doesn't have the capacitor on the outside of mine.  It does have twin jumper leads - and I have a picture to show you.


I don't think the motors are overloading the speed controller causing this problem when she is in the water and also you thinking the props too close to the rudders on your model are having some affect.   I very very much doubt it.  Maybe your speed controller has (shall we say) 100% forward speed and only 75% reverse speed.   Then again, even with this, you should obtain some reverse movement.


Couple of things you could try when she is out of the water - try putting a bit of resistance using a piece of balsa wood or an old clothes peg on the coupling of one of the motors when the motor is running in reverse  -  be careful you don't jam the motor up and see if this has any affect on the opposite motor - sometimes the opposite motor will either speed up or come to a standstill.


Try slowing both motors down together using friction on the couplings to see if it is the speed controller being overloaded.


Or, something else which has just sprung to mind and has caught me out many times with these type of speed controllers / ESCs with the brake fitted - is there is a delay in between forward and reverse - this is to account for the braking affect.   This is where the motor just stays stationary for a moment or two.


See how you get on.

[Allen A]

Question ...  I took the props off with a view to getting bigger ones and noticed they are not the same, seem to be opposites of each other, could this be what my none reversing problem is about ...  should twin props be the same configuration  and/or is there a 'left and right' fitting to them ??

[MikeMcP]

I would expect them to be different and contra rotating
that is one goes clockwise, one goes anti-clockwise so the torque balances out
you need to configure your ESCs so that one turns to the left and t'other turns to the right when commanding forwards
then when you command reverse, they'll both turn the opposite way
and your getting forwards when you ask for reverse because one is going faster than the other, or the ESCs aren't set up the same


hope that make sense
it did in my head before I wrote it!

[Allen A]

Hi Mike .... hmmm .. you say ESC's .. plural, ... do I need one for each motor then and I take it both will bind to the one TX  ?


I do understand the concept of contrarotation, a simple fix to me would be to wire one of the motors the other way around so both then rotate as opposites, or is that a no no .... also is there a 'left and right' prop or doesn't it matter which side they go, sorry to be so 'dumb' but a complete novice as I say with this sort of thing .. now .. give me model trains or cameras and Im away .. 

[MikeMcP]

ah no that's me assuming you have two!
wiring both to the same ESC should be ok
just make sure they spin opposite ways

[MikeMcP]

and as for left and right prop
whichever way you do it, it'll be the other way
but it doesn't matter
I'm guessing you can flip your transmitter so forwards really is forwards

[Allen A]

Success .. (lucky cess ..  ) .... I simply reversed the wiring on the one motor, figured out the correct configuration of the props and violins as the French say ... tested in the bath and I have fwd on fwd command and reverse on reverse command .. many thanks for the help and especially the patience here .. 


... and so back to the No 1 boat ... watch this space ... !!


Oh a static shot from late-ish last night testing the No 2 boat again (to no avail at that time of course) ... around 10pm on a quiet and calm canal 

[MikeMcP]

excellent - look forward to seeing it in action!

[dodgy geezer]

If one prop is going forwards and one backwards they will fight each other.  The one going backwards will be less efficient, so the one going forwards will win. but the boat will be slow.  I would have expected that you would get a turning movement, and would have needed to put lots of trim on...?   

[John W E]

hi there Allen as Dodgy Geezer has just pointed out; with both motors wired up to turn in the same direction and fitted with counter rotating props; the model should have tried to do circular movements, rather than go forward.  This is how life size vessels decrease their turning circles.   So, if this is the case, and your model was turning in circles rather than going forward or reverse - we may have helped you solve the problem a bit earlier - slight mis-communication between all of us.   As long as it is sorted good luck there.


John

[Allen A]

Hi gents .. I do have video of it in action but cant seem to post here ... you are right, both motors were wired to turn the same way and has contrary props, something I hadn't realised until the other day as I assumed them both to be the same configuration .. the thing being whereas it didn't actually run dead straight, it didn't circle either .. just drifted off a little to one side slightly ...  have yet to sail it on the canal again but in a test in the bath as I say I had correct fwd and reverse action .. seemed to be a little quicker too but will have to wait until I have more space to confirm that.


Probably right about the mis-communication John, have to hold my hand up there as my fault perhaps due due to my inexperience ... but Im learning ..

[Backerther]

Allen A,


The static shot in the dark with the lights on is "so brilliant" and looks better than in the daytime..??? Oh, excuse me, sir.!!
Posting the video is rather difficult for you than to set the model boat right.....the next problem to solve...?

Anyhow, I am also looking forward to seeing the video even though it should require a long time.

[dodgy geezer]

hi there Allen as Dodgy Geezer has just pointed out; with both motors wired up to turn in the same direction and fitted with counter rotating props; the model should have tried to do circular movements, rather than go forward.  This is how life size vessels decrease their turning circles.   So, if this is the case, and your model was turning in circles rather than going forward or reverse - we may have helped you solve the problem a bit earlier - slight mis-communication between all of us.   As long as it is sorted good luck there.


John

I suspect that with a narrow hull and little distance between the two props the turning moment would have been slight, and if the rudders were trimmed for straight running at an early stage it might be hard to notice. The most obvious effect would then be easier turns in one direction rather than the other. But if the boat was travelling slowly it might be hard to even notice this...

[Allen A]

I suspect that with a narrow hull and little distance between the two props the turning moment would have been slight, and if the rudders were trimmed for straight running at an early stage it might be hard to notice. The most obvious effect would then be easier turns in one direction rather than the other. But if the boat was travelling slowly it might be hard to even notice this...

Hi .. you're spot on ... it was a slight drift off movement as you say and yes it did turn one way easier than the other .. it wasn't that slow I think, as although it didn't ride high, it did produce a visible bow wave and engine wake, so hoping for improvement there too .. one other thing, it is ..( was ?) .. a bit noisy, would that be due to the props fighting each other, possibly causing a bit of vibration .?


Hopefully if the weather holds I will sail it again tonight and let you know the results.

[Backerther]

Just for your reference from my experience of operating Rc boats.
The noise will normally be bigger as the boat goes faster on the water which you may know. It would normally and mainly come from motor, construction of a coupling and mis-alignment between the motor shaft and prop shaft.
I don't think the props have something to do with this noise directly since nearly the same set up in my boat with yours has never
caused abnormal noise so far.


Wishing you a successful night run,

[Allen A]

Soooooo  ... just done a test run with the No 2 boat .. and yes running a bit faster and quieter too .... BUT ... boat started acting a bit strangely, wandering off to one side, turning one way more than the other again and a 'Oh Oh' thought crossed my mind ... yep, lost my s'board prop, unscrewed itself from the shaft ..  apart from that it started as a successful test so back to square one in a way and time to order two new props.


On the plus side got a new motor and ESC for the No 1 boat and having fitted them will try a late-ish test sail with it weather permitting this evening ..

[Allen A]

Sometimes, despite all the setback, things can and do fall into place ...  the No 1 boat with its new motor and ESC performed well, has a good turn of speed and sits up well at speed too  .. frankly it scared the heck out of me being unprepared as I was for the performance it gave and took a little bit of time to get used to the controls on the TX for it.


One thing I have discovered is that you cant film and control a boat at the same time, so a still pic of the No 1 boat lit up for now, but rest assured as soon as I can get my son and/or grandson to join me I will get some video, for now though I am very pleased .. Ive got a PT Boat .. 

[Backerther]

Oh, my goodness !  You ,too...and me,too !! stbside prop...
I lost the prop in the latest run. A Pt boat is normally, always sailing fast on the water which I suppose may be one of the
causes to loosen the prop...   We had better have some spare props like a real boat..  
Anyhow, congratulations for a good result.


The second pic shows my first PT-109 wandering unstably in the shake-down run made so many years ago.
The boat was not equipped with the bilge-keels while the second equipped as seen in the first pic.
I think this may have worked mainly very well in every aspect of maneuverability on the water...