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[Rob47]

two image Chris and the bearings can be seen clearly so no problem that I can see for Tiger


Bob

[littoralcombat]

Hi Bob,
Is the second image the arrangement you have on your HMS Bristol by chance?
Nige

[Geoff]

From the last posted picture of Tiger's shafts it does appear that the trust bearings are absent so the thrust will pass straight to the engines and put a lot of pressure on their bearings longitudinally which they are not designed to take, both significantly increasing friction and therefore current consumption. As the bearings overheat they may partially seize and then blow the fuses. It will also overload the universal joints, and as the other picture shows there seems to have been some longitudinal movement within one of the engines this all seems to suggest the prop thrust is being born by the engines. The thrust will also probably be sufficient to push the engines slightly out of alignment so again further friction and stress.


I would counsel you remove the prop shafts by sliding them aft and fit some thrust bearings to abut against the outer casing as the later pictures show on another model. This should fix your problem.


However if I understood an earlier comment that some resin had dropped onto the rotating shaft precluding its removal then there are two solutions:


Firstly run the engines on the bench and use a file to file off the resin until you reach metal and then the shaft can be removed by sliding it aft. A bit like a miniature lathe.


Secondly you can construct a strong internal "L" shaped bracket fixed to the hull bottom with a hole which the shaft goes through and use that to take the thrust with a collet and a couple of washers either side. It may mean that the engines will need to be mover forwards about an inch


Hope this may help.


Cheers


Geoff



 

[frogman3]

Chris hate to disagree with you but the prop tube is not full length.  Remove propeller, disconnect shaft, slide it clear of A frame put thrust bearing over shaft and reassemble making sure the bearing is no to tight against end of tube, same internally. if you like I will take a couple of pics to show it.


Bob

HI Bob an Nige an Geoff
please understand   that my prop shafts are INSIDE the stainles steel prop tube SO NO WAY CAN I FIT them thrust collors on i hope you under stand guys as Bob your pics show just the prop shaft doesnt it well mine are in STAINLESS STEEL prop tubes FULL LENGHT RIGHT DOWN  TO ALL 4 A FRAMES
https://ibb.co/QKyBGbX
chrisb

[Rob47]

Hi Bob,
Is the second image the arrangement you have on your HMS Bristol by chance?
Nige

Nigel yes Nate it is


Bob

[Rob47]

HI Bob an Nige an Geoff
please understand   that my prop shafts are INSIDE the stainles steel prop tube SO NO WAY CAN I FIT them thrust collors on i hope you under stand guys as Bob your pics show just the prop shaft doesnt it well mine are in STAINLESS STEEL prop tubes FULL LENGHT RIGHT DOWN  TO ALL 4 A FRAMES
https://ibb.co/QKyBGbX
chrisb

Chris you have totally lost me and I cant understand the problem, you are saying yours are different because you have tubes and I only have shafts,  if you look you can see the tube just showing as per 1/1 scale, yours cant be full length otherwise you would not have the shaft running through the A frame, the method of fitting has been explained here, remove prop disconnect saft from motor pull back couple of inches the slide the bearing over the shaft and tighten all up.  You say your tubes run down al the way to the A frame, but that's not what your picture show.  It shows a prop tube stopping just out side the hull then the exposed prop shaft running into the A frame exactly the same as both the pictures I have posted.
I cant explain it any better Chris


Bob

[Geoff]

Okay, I think I understand. What we are seeing in the picture is an outer stainless steel cover which does not rotate. There is another solid inner shaft inside this which rotates so there is no way a shaft bearing will fit in the traditional way, is that right?


If this is correct then theoretically the thrust can be taken by the "A" frame as this is directly linked and supported to the hull by the outer stainless steel casing, in which case no other thrust bearing is needed.


If this is correct, and I've never seen it built this way before, which explains the confusion. Sadly it may also introduce significant drag between the rotating shaft proper and the outer stainless steel casing depending upon the internal clearances and therefore higher current consumption.



So, with all engines disconnected do the four shafts rotate easily.


There are always solutions to any problem.


Cheers


Geoff

[Geoff]

As an add on, if the thrust is not taken by the "A" frames then it will push directly onto the couplings and the engine bearings which will cause issues.


Cheers


Geoff

[Rob47]

Geoff
Are we talking about bearings in the engineering sense i.e. inner and out or the thrust bearings that you can see on my images i.e. the conical parts with grub screw? these are what I call thrust bearing along with a collet at the other end, which in essence creates a tube with a shaft in it which can rotate but with a bearing either end has no lateral movement.


Bob

[frogman3]

Okay, I think I understand. What we are seeing in the picture is an outer stainless steel cover which does not rotate. There is another solid inner shaft inside this which rotates so there is no way a shaft bearing will fit in the traditional way, is that right?


If this is correct then theoretically the thrust can be taken by the "A" frame as this is directly linked and supported to the hull by the outer stainless steel casing, in which case no other thrust bearing is needed.


If this is correct, and I've never seen it built this way before, which explains the confusion. Sadly it may also introduce significant drag between the rotating shaft proper and the outer stainless steel casing depending upon the internal clearances and therefore higher current consumption.



So, with all engines disconnected do the four shafts rotate easily.


There are always solutions to any problem.


Cheers


Geoff

HI Geoff yes youve got it in one you are correct just hope Bob can understand what you are sayin as yes you are correct as ive fitted these long prop shafts tubes in nearly all my models eceptin on my edinbough  an never had this trouble before but glad you see what i mean as yes them STAINLESS STEEL PROP TUBES do look like the inner shaft but they are the outer tube glad we have this sorted
ATB guys
chrisb

[frogman3]

Geoff
Are we talking about bearings in the engineering sense i.e. inner and out or the thrust bearings that you can see on my images i.e. the conical parts with grub screw? these are what I call thrust bearing along with a collet at the other end, which in essence creates a tube with a shaft in it which can rotate but with a bearing either end has no lateral movement.


Bob

HI Bob i fitted these prop tubes as they are a lot cheaper than your idea im afraid to cut costs hope you understand
chrisb

[Rob47]

Chris
Nope still not with it and as my full set of bearing cost £5 your shafts must have been dirt cheap Fleet scale do them set of 4 around £10 think i get what you are saying, seems an awful convoluted way of doing things, why make a simple task harder.
Amway I am out of this now, have fun sailing


Bob

[frogman3]

Chris
Nope still not with it and as my full set of bearing cost £5 your shafts must have been dirt cheap Fleet scale do them set of 4 around £10 think i get what you are saying, seems an awful convoluted way of doing things, why make a simple task harder.
Amway I am out of this now, have fun sailing


Bob

OK Bob sorry you dont understand
atb
chrisb

[ballastanksian]

Cor! I liked the look of her on the water. Very regal indeed and quite American Navy looking in some ways.


I hope you get your drivetrain all sorted out and the new motor does its job. I reckon she will be a wonderful sailer for you!

[frogman3]

Cor! I liked the look of her on the water. Very regal indeed and quite American Navy looking in some ways.


I hope you get your drivetrain all sorted out and the new motor does its job. I reckon she will be a wonderful sailer for you!

HI Well as soon as the new motor comes i will fit it in an then try her again an yes im pleased at how she looks on the water but OH MY she is heavy
ATB
CHRISB

[frogman3]

Chris,


Not to teach you to suck eggs, but once you have installed the new motor and UJ I would put a bit of light oil on the motor bearings and run the motor in for half and hour and keep an eye on motors and shaft temps. All the best let’s hope this is hopefully your major issue with the drive system. 

HI Dave yes i will do that really should have fitted oil ways in the prop shafts tubes but i thought that the grease in side the tube would do the job but havin said that all 4 shafts spin freely so why this shaft problem happened i dont know but them motors are very powerfull as my boaty m8 held onto her bow to stop her from floating away an when i tested the throttle she shot forward an nearl pulled my m8 into the water an he was shocked at the motors
 props thrust so to move this very heavy ship its just what i needed an to cut down the power a bit im thinkin of lowerin the dual rates on the T/X from 100% down to 70% so the eletrics wont get full power to blow fuses an wirein an such but will see how that works against the wind as she is big an a good wind cather
ATB HOPE you feel better sir
chrisb

[Geoff]

Okay, to clarify a little further, Tiger has been fitted with long narrow prop tubes and shafts such that from the pictures it looks like the silver bit is the rotating shaft but actually its the exterior of the prop tube so does not rotate. I am still of the opinion that issues are being caused by where the thrust is going. As Tigers shafts are completely cased and therefore directly support the "A" frames then the thrust can be taken by the "A" frames (as its really pushing on the outer prop shaft casing) without causing any distortion. So I would counsel you check the clearances at the "A" frames to make sure that is where the thrust goes first and not onto the couplings and direct to the engines. Put one of two small brass washers between the prop and the "A" frames and they will act as thrust bearings. You want about 1mm float at this point- but important the shaft is free to move forwards on to the "A" frames to take the thrust.


Its important to ensure that there is room for the plastic part of the couplings to slide horizontally a few mm as this will prevent the thrust going to the engines. This can be done simply by making sure there is a 1mm gap between the brass collet (brass grooved thing) and the plastic part of the universal joint at each end). This will mean there is no direct horizontal thrust acting on the universal joint or the actual engine. Same for reverse - put two lock nuts on to stop the shaft pulling out.


As the shafts rotate freely this will remove any thrust bearing issues and consequent overloading of the engines and high current consumption and will eliminate this aspect as a concern.


I only ever use grease in my prop shafts and don't bother with oiling tubes as in practice I have found little or no leakage for years.


Hope this may assist.


Cheers


Geoff


 

[frogman3]

HI Geoff yes you are right that the prop shafts tubes are long about 15 " stainless steel prop tube an ive always uesed these in my ship as the prop tube is a lot cheaper than the short tube an uncorvded out prop shaft as to buy these would could me a lot of money x4  so for me the prop tube an shaft inside are the way to go an yes with grease inside them them are good an stronger too than  just a open prop shaft an yes i have about a 1mm move ment on them shafts so they normally are good an the other 3 all motors an prop shafts all work ok an my m8's put a amp meter across the motor terminals an found each motor is drawin near 8 amps each x4 so thats 32 amps in all 4 motors so havin 40 amp fuses fitted in the system should be ok just be glad when the new motor comes but dave may be right as when i looked in the hull after the accident with u/j the lock nut had come lose so when i put it all back in i' make sure them lock nuts are tight


CHEERS
chrisb

[frogman3]

HI Bob this is for you so you can understand my prop configeration
an here is a stainless steel prop shaft cost 18 pound an lenght 16"
so you if poss you can  see what i mean on them prop shaft not bein able to fit thrust collars like you have on your ship an there is also a close up shot showin the inners drive shaft inside the outer tube fitted with a prop now i hope you can see what i was talking about
ATB Bob
chris
https://ibb.co/sbqQWt5
https://ibb.co/W5vqTtV

[Geoff]

Interesting, and I assume the props were in the water when the ammeter was attached?  If not once in the water the current consumption will be higher. In my opinion 8 amps per motor still seems very high which continues to suggest a miss-match in some way. As mentioned before Iron Duke is running two car blower motors driving four 45mm 4 blade props on 6 volts and max current is 3.4 amps. I don't know what the RPM is but would speculate its not more than 3000 rpm so on the low side.


Do please consider it may be better to put a 10 amp fuse on each engine and a 40 amp fuse on the speed controller as in that way you could loose one engine and not leave the model stationary.


Also have a good look at the fuses as there are different types, quick blow = pretty nearly instantaneous, slow blow = they will take more amps for a few seconds but blow if sustained and then continuous rating = they will run certain amps all day without blowing.


As another thought, I assume you are running tiger on 12 volts, what happens if you run on 6 volts as this will immediately and approximately half your current consumption. 12 volt motors will run happily on 6 volts, just less power but if she goes fast enough?


Cheers and good fortune


Geoff

[tweety777]

As another thought, I assume you are running tiger on 12 volts, what happens if you run on 6 volts as this will immediately and approximately half your current consumption. 12 volt motors will run happily on 6 volts, just less power but if she goes fast enough?

This sounds really off. The engine needs a certain amount of power, cut the voltage in half and you'll need double the amps to get that power. The engines will simply take what they need so I don't see how this will do any good.


I agree that even 8amps per motor sounds really much. My Well Enhancer (probably a lot smaller then this cruiser) runs happily at less then an amp at full power with 2 38mm props, so those are not that much smaller. Could it be that the props are too small for the ship causing them to have lots of friction to actually get the ship moving? Also, maybe a 1:2 gearbox can help, this can also help take away the problem with the u/j.


Greetings Josse.

[frogman3]

Interesting, and I assume the props were in the water when the ammeter was attached?  If not once in the water the current consumption will be higher. In my opinion 8 amps per motor still seems very high which continues to suggest a miss-match in some way. As mentioned before Iron Duke is running two car blower motors driving four 45mm 4 blade props on 6 volts and max current is 3.4 amps. I don't know what the RPM is but would speculate its not more than 3000 rpm so on the low side.


Do please consider it may be better to put a 10 amp fuse on each engine and a 40 amp fuse on the speed controller as in that way you could loose one engine and not leave the model stationary.


Also have a good look at the fuses as there are different types, quick blow = pretty nearly instantaneous, slow blow = they will take more amps for a few seconds but blow if sustained and then continuous rating = they will run certain amps all day without blowing.


As another thought, I assume you are running tiger on 12 volts, what happens if you run on 6 volts as this will immediately and approximately half your current consumption. 12 volt motors will run happily on 6 volts, just less power but if she goes fast enough?


Cheers and good fortune


Geoff

HI Geoff yes in the water for load on motor amps test an i think 6v is not enough power for these motors as the range starts at 12v an up to 36v an the ESC are rated at 320 amps so i should not blow them an fuse type it dont say what type they are just 40 amps so im gonna fit it all back togeather when that new motor comes an try tiger out at a low power by dual rates an see how she goes fingers crossed
cheers  Geoff for your input
atb
chisb

[tweety777]

HI Geoff yes in the water for load on motor amps test an i think 6v is not enough power for these motors as the range starts at 12v an up to 36v an the ESC are rated at 320 amps so i should not blow them an fuse type it dont say what type they are just 40 amps so im gonna fit it all back togeather when that new motor comes an try tiger out at a low power by dual rates an see how she goes fingers crossed
cheers  Geoff for your input
atb
chisb

How many ESC's do you use? 1 per engine? 2 or only 1? Is it possible that you wired the ESC's and/ or engines such that they actually get either 6V or 3V? That could also explain the high amps, especially since Tiger sails pretty well which seems to suggest that the props are powerful enough.


Greetings Josse

[frogman3]

This sounds really off. The engine needs a certain amount of power, cut the voltage in half and you'll need double the amps to get that power. The engines will simply take what they need so I don't see how this will do any good.


I agree that even 8amps per motor sounds really much. My Well Enhancer (probably a lot smaller then this cruiser) runs happily at less then an amp at full power with 2 38mm props, so those are not that much smaller. Could it be that the props are too small for the ship causing them to have lots of friction to actually get the ship moving? Also, maybe a 1:2 gearbox can help, this can also help take away the problem with the u/j.


Greetings Josse.

HI Josse yes i feel you are right on the batt voltage  an i dont want to change things anymore as its all been changed abot 5 times so im goin with what ive got if i can get 15 mins sailin with her then i'll be pleased an yes this is the first time ive had motors on direct drive as all my other big ships had a 3 to 1 ratio cambelt drive an i never had any probs but i hope to cure this just got to keep tryin as ive invested to much dosh in tiger
cheers
chrisb

[frogman3]

How many ESC's do you use? 1 per engine? 2 or only 1? Is it possible that you wired the ESC's and/ or engines such that they actually get either 6V or 3V? That could also explain the high amps, especially since Tiger sails pretty well which seems to suggest that the props are powerful enough.


Greetings Josse

HI AGAIN i am usein 2 x 320 amp ESC  so its 1 esc to power two motors an the same on the other two motors an i alway used this layout with multi engins ships like my big USS NIMITZ CVN 68 aircraft carrier at 9 ft long but again with 3-1 ratio cambelt drives an they were made by MFA but they dont make these units no more but NIMITZ sails lovely so this direct drive may be a bit of my problem
 https://ibb.co/pb1BBP3
cheers
chris