Or the British way. Sell it on to Brazil or some other third world!!!!Of course you could always set fire to it, like the Vikings and have a great day out at the lake.
boatman's 1/72 HMS Tiger C20 build
- Thread starter boatman
- Start date
End of the day, Chris will solve Tigers issues.
NO WAY mr John after all the dosh ive put into it but it would make your day wouldnt it lolOf course you could always set fire to it, like the Vikings and have a great day out at the lake.
AN YES Doug the british way is just plain stupid an i think they cant do their sums these ship costin a 100 an 80 millon quid then they flog it for 3 millon something wrong there
AN YES Doug i certainly hope so but only time will tell
chisb
HELLO GUYS
well ive fitted in just the front two X MFA 540 motors an gave them a run on there own an well im quite dissapointed NOT VERY POWERFULL an so i ran all 4 motors thats the 2X MFA MOTORS AN 2 X JOHNSONS MOTORS that are already fitted in an too me the JOHNSONS MOTORS seemed more powerfull so im not goin to take out the JOHNSONS MOTORS but i will get the other 2 x MFA 540 MOTORS READY to just be fitted in an i cant send them back as the chap wont give me much as i paid as he said they will have been used an he is quite right so i will have too keep them an 2 pics the MFA ones are the ones with the yellow sticker on them an johnsons towards the rudder OH DEAR I THINK ill have to look at some bigger motors an props but yes Andy i know they will draw more current but so far the motors an props i have i dont think are up to the job
chrisb
well ive fitted in just the front two X MFA 540 motors an gave them a run on there own an well im quite dissapointed NOT VERY POWERFULL an so i ran all 4 motors thats the 2X MFA MOTORS AN 2 X JOHNSONS MOTORS that are already fitted in an too me the JOHNSONS MOTORS seemed more powerfull so im not goin to take out the JOHNSONS MOTORS but i will get the other 2 x MFA 540 MOTORS READY to just be fitted in an i cant send them back as the chap wont give me much as i paid as he said they will have been used an he is quite right so i will have too keep them an 2 pics the MFA ones are the ones with the yellow sticker on them an johnsons towards the rudder OH DEAR I THINK ill have to look at some bigger motors an props but yes Andy i know they will draw more current but so far the motors an props i have i dont think are up to the job
chrisb
Well that sucks like a sucky thing. This Ship is not being kind to you is she.
So the new motors seem weak compared to the Johnsons. What voltage are they getting? If the Johnsons are 12v and are getting 12v they are running full tilt. If the MFA's are set to run 15v and are only getting 12v then they will seem weaker.
I think the lack of power to propel the ship through the water, lies not so much in the speed the motor is turning But the useable power. Torque at the shaft/screw.
The best comparison I can think of right now is the good old Electric drill Verses an electric screw driver.
I have a mains power Black and decker that can turn very fast and a 10mm drill eats into wood quick as you like. However If I hold the chuck of the drill I can stop it quite easy.
I also have a little Black and Decker ixos screwdriver. About 1/8 the size of the big mains power job and runs at around 20v on a re-chargeable battery. It is very slow But impossible to stop with a hand. Its not fast but has huge torque.
Try to find out more about low rpm motors for R/C lorries and rock crawlers. I think I sent you a link to one such a while back. Slower motor = less draw on the battery but more umpff at the screws. The screws have a better chance of taking hold in the water and not thrashing it to foam. (cavitation). and can turn a good size screw which will add propulsion.
There is a video on YouTube of an R/C tugboat pulling a 'fully grown' man in a wooden row boat across a lake. Two 12 v low speed motors with large screws.
I read in the post when you purchased the new motors he said you could return them...It would be worth a try, and you have only used two of them. So you'll get most of your money. Was he a shop or was it a private sale?
So the new motors seem weak compared to the Johnsons. What voltage are they getting? If the Johnsons are 12v and are getting 12v they are running full tilt. If the MFA's are set to run 15v and are only getting 12v then they will seem weaker.
I think the lack of power to propel the ship through the water, lies not so much in the speed the motor is turning But the useable power. Torque at the shaft/screw.
The best comparison I can think of right now is the good old Electric drill Verses an electric screw driver.
I have a mains power Black and decker that can turn very fast and a 10mm drill eats into wood quick as you like. However If I hold the chuck of the drill I can stop it quite easy.
I also have a little Black and Decker ixos screwdriver. About 1/8 the size of the big mains power job and runs at around 20v on a re-chargeable battery. It is very slow But impossible to stop with a hand. Its not fast but has huge torque.
Try to find out more about low rpm motors for R/C lorries and rock crawlers. I think I sent you a link to one such a while back. Slower motor = less draw on the battery but more umpff at the screws. The screws have a better chance of taking hold in the water and not thrashing it to foam. (cavitation). and can turn a good size screw which will add propulsion.
There is a video on YouTube of an R/C tugboat pulling a 'fully grown' man in a wooden row boat across a lake. Two 12 v low speed motors with large screws.
I read in the post when you purchased the new motors he said you could return them...It would be worth a try, and you have only used two of them. So you'll get most of your money. Was he a shop or was it a private sale?
HI Ian many thanks for info an its a shop but i was goin to buy the 555 motors but the chap said they were low power an id be better off with the 540 motors an yes all them motors are gettin just 12v even though as you say the 540 motors are rated up to 15v but as for sending them back i think how much it will cost to return them i wont get that much back as the motors were only 7 quid each an he said we will see how much so it sounds like he gonna knock me down on return price so i'll keep them an im thinkin of just goin to my local model shop as he had some motors out of these portable hand drills so i think i'll see how much he wants for them as im at my wits end but i must admit i have not tried her out yet with these new motors but just how the sound they are not pokey so soon will take her for a sail first nice evening i get an not too hot an see what she does but cheers for lookin in
chrisb
AN JUST had another thought i wonder if i would be better off with them cam belt drive for tourge to props as i have two up in model room an i could take the two out of my norfolk so i would have 4 cam belt drive unit where it 3 to i ratio so if the motors are doin 3000 rpm then the prop shaft will be spinning at a 1000 rpm so i could try that as norfolk may not need these cam belt drive an fit just direck drive for norfolks motors as she does go to fast anyway im thinkin lol
chrisb
chrisb
Very well explained Ian. The motors can spin the props fast but that doesn't mean the props will 'bite' the water and give you propulsion.
Years ago a friend changed the motor on his motor yacht. Great he thought, bigger engine more speed!!! Nah. An old boy in the shipyard told him needed to 'match' the prop to the motors output. A year or so later he changed the prop in Greece after smashing it up a tad. The Greek fitter got him a different prop that matched the yachts power/torque!!!! Overnight he went from 3-4 knots to just over 8kts!!
I think it may be worth a few hour researching torque, power out and propeller, pitch and diameter.
Mate, you have done wonders, the end post is in site. Before spending more dosh - try and establish what is causing the mismatch before you chase your self in circles.
If I'm talking round spherical things then please ignore me!!!
HI Doug yes you also maybe right but i must admit this is the heaviest ship ive ever built an the first direct motor drive as all my other ships had cambelt drive an ive never had these probs before so i may do as i last said an fit her out with cambelt drives an see how that goes an a bit bigger props if they are needed but i hope not as these props are 35 quid each thats times 4
ATB
CHRISB
ATB
CHRISB
I take it by your comment the motors are direct drive? To my simple mind, remember I have no experience of building these beasts. Loads of speed being fed directly to the prop! Maybe they spin but don't actually 'bite' into the water. Bit like my lads milk frother!!!!
Try the new motors separately and see what if anything you get in the form of movement. What the big boys do, they Med moor the ships, (Tie up stern to the dockyard wall), they start applying power to check out the propulsion systems. That would also mean you wouldn't have to swim/wade out into your water to retrieve Tiger in the event of a failure.
Also, on your control console, is power applied gradually or is it motors on or off?
I don't envy you your problems Chris. To get this far and start hitting snags. But stick with it dude - you'll get there.
What is a Cam belt drive please?
Dont start pulling bits out of Norfolk.!
Try with the four new motors that are all the same. You have those so you might as well use them.
Is your test tank large enough to do a pull test. If you have a 7 foot boat a 10 foot tank is plenty. Just tie the boat up with bungy cord/elastic!
If you can reply to these questions I can have a chat with a mate here that is really into R/C boats.
If you had to guess the sailing weight of the boat what would you say.
The size of the screws: diameter pitch and number of blades. Photo?
Motors used volts and amps and all that
ESCs max output
Batteries 12v? Amps....
You probably think I'm a pain in the butt, but I really want to help you sort this
HI Doug cheers for the info on how they check real ships on propushlion an to ansewer your question on the R/C control T/X THE power can be applaied gently or sharply as its just pushin a controll stick that is the throttel like on the real ships BUT on my new carsons R/C T/X THERE IS NO RATCHET controll
so i can take the power up a few steps at a time an because no ratchet its very easy to give the power flat out instead of a bit at a time an ive been askin around on model boat mayhem if Carsons do a ratchet set for my T/X but so far no luck an if i was a bit braver i could do it myself as i have the ratchet an i was goin to try an fit it into the T/X an i took all the main screws out the back of the T/X
but there was still two inset screws right inside the casein an to me it looks like they are holdin in place some parts of the PCB BOARD an so dint dare undo them in case as when i pull off the back casein there might be bits spring everywhere so i aborted the attempt as i have done this before on cheap R/C T/X 's but this carsons cost nr £200 an i dont want to take that chance ON BUGGERIN IT UP
if you see what i mean an yes i think i will put her in the test tank an see how much thrust these props an motors give but there is a problem there as she cant hardly move as tiger is an inch under 8ft long an the test tank is 8ft in tolal so she cant move more than an inch which is not a lot off good as had the same prob with my nimitz carrier as she was about 8ft 6" but i was lucky as with a big carrier there is so much overhang on the bow so she just scraped in an yes i hope i will get there
ATB cheers for the info an help much apprecaited
chrisb
It’s just a shame this wasn’t five years ago. I was working at Sunseekers and knew one of the propulsion engineers. Unfortunately we’ve both left and gone our separate ways.
AN HI Ian no you are most certainly NOT a pain in the butt as i know you want to help me on tiger probs an if you read the reply i said to doug above you will see that movin tiger in the test tank is no go as she is near as big at the test tank but i will try her in an open up the throttle an see how much propullshion she has on them motors i have fitted in an regards your qeustions Ian give me a few hrs to take a pic of a cam belt drive an then i'll have to wheight each bit of tiger about 7 parts then add all the wheight togeather as cant do it when she is all togeather as she is to heavy to lift an i dont think i would get a proper reading on them bath room scales as they wont take something as heavy as tiger so will get back to you sir in a few hrs hopefully as we are havin jen freinds over today an im teaboy lol but i WILL GET BACK WITH THEM ANSWERS Ian an many thanks to you also for your help much appreciated
chrisb
WELL Doug cant be helped can it as if i built this ship ten yrs ago i could have bought all 4 MFA CAM BELT DRIVES an then i think it would cure the prob as i know Ian said dont touch my NORFOLK but it may come to it that i will have to take out her cam belt drives an the have her as direct motor drive as NORFOLK is twice as light as tiger is heavy an norfolk goes to fast anyway an i use only about half power on her an she is like a greyhound of the seas an better still on her R/C T/X i have fitted in a ratchet controll so i can keep her at a fair scale speed if you understand what i meanIt’s just a shame this wasn’t five years ago. I was working at Sunseekers and knew one of the propulsion engineers. Unfortunately we’ve both left and gone our separate ways.
cheers
chrisb
HI Ian well here is a pic of them cam belt drives in norfolk as it about 3 to 1 ratio an the motors in there are gruapner 6oo speed motors an these are what ive always used in my ships but cant buy them now same as cambelt drive made by MFA 
AN TOTAL all up wheght is as nr as i can get it is 88 1/2 pounds so bloomin heavy an props r 33 mm pic below 
Wowsers, over 40kg!!!
Muscles like the Hulk moving that thing around!!!!!
So 88 1/2 pound is not that much. (40kg) not that much. I was expecting 188Lbs the way you was talking. lol.
So a cam belt drive is a gearbox with a belt. right.
As over £40 a pop for a drive unit. it would be cheaper and easier to put a slower motor in.
You should be able to buy those motors still. You can get them over here anyway.
https://modelskibet.dk/shop/335-el-motorer/6176-speed-600-72-v/
If they are the right ones that is. £20 a pop.... but then you still have a fast motor. I am sure you could find them in the UK.
Try here: https://www.motorsandrotors.co/index.php?main_page=product_info&cPath=139_274&products_id=6259
I would go for something like these.
https://www.modelsport.co.uk/product/lrp-truck-puller-3-br-motor-6300rpm-12v-37685
They cost about 35 quid, but you wouldn't need the reduction box.... They can turn a 130mm screw! and they are the recommended motor for R/C tug boats.
I would say that they would push Tiger more than quick enough.
If I may say I think the props are a bit small at just over an inch. I was expecting them to be at least 2inch. Is that the radius you have given or the diametre?
It looks like there is not a lot of room for much bigger props though.
I hope that you find some of this useful. Perhaps a talk with the chap in the Modelsport link could help clear things up.
Say hi to Jen.
I really feel for you Chris. The Tiger is really biting back. I hope all the setbacks at this late stage don't dampen your spirits. You will have a break through soon! :tongue-out3:
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