USS Melvin by gluedandscrewed - RADIO

[gluedandscrewed]

you do know, bill, when they say pictures dont lie? thats a lie!!! but thanks anyway

[lmagna]

gas

 

I REALLY hate making  comments on fantastic work like this as suggestions always seem to be critical and there is nothing to criticize on what you accomplished so far.

 

I was wondering, if you ran your string in a figure eight  between the director and the 5" allowing you to fasten the 40s to the other side then each 40 would then track the same as the 5". When the 5" tracks outward to Port for example so would the 40 on the port side. The same would happen to the Starboard 40 when the 5" trained outward to the Starboard. Does that make any sense to you? The same thing could be done by extending the arms of the 40s and attaching them on the opposite side but the amount of travel would be less.

 

Lou 

Edited December 8, 2017 by lmagna

[gluedandscrewed]

figure 8 i believe would turn the 5 and the director in opposite direction lou,,the problem is the proximity of the 40's "shaft" to the wall , cant mount a "pulley" on them and the flimsiness of the superstructure construction, its all just 1/16 basswood,,,i went thru several "engineering changes",,,plus with the 40's counter rotating we got them damn kamikazies coming and going

[lmagna]

Whoops

That's why people like me should leave things like this to more capable people like you! I was so wrapped up in the 40s that I missed the more obvious and necessary 5" gun director relationship.  The only way to do it would be to replace the arms with another set of pulleys like you use elsewhere and make the line go around them all in the same direction!

 

Carry on MacDuff I'll be pealing some potatoes back in the corner watching again.

Lou 

Edited December 10, 2017 by lmagna

[gluedandscrewed]

not more capable lou, just learned from past mistakes didnt have room for pulleys on the 40's, tried going thru the shafts them self but without the mechanical advantage of the pulley it put too much stress on the whole structure, thus the arms..still dont know if one heavy duty servo will have enough juice to work the whole apparatus and if there will be too much slack and stretch in the ropes to make it all worthwhile,,, we shall see

[gluedandscrewed]

against all odds and common sense it actually works, got all the 5 inchers,torpedo tubes and 2 bofors to rotate, somebody pinch me!!!

[popeye the sailor]

super duper work GaS.......looks very nice  

[gluedandscrewed]

progress report, 3 months 1 week and at least 500 hours, still many knick knacks to install,, than the boilers and steam turbines,,

[popeye the sailor]

awesome job so far........very nice to see her at this point!  hard to believe this is scratch built.  done very well in the detail dept too   

[gluedandscrewed]

have been procrastinating a bit lately, too damn cold, global warming my ****,  been trying to engineer the means of locomotion for this 6 foot beast, my prop shafts are 5/32, not the most widely used dimension making it a bit more complicated as far as buying components for the drive line, open to any suggestions in the way of motor size, prop dia. etc,,can swing up to a 2 inch props

[gluedandscrewed]

guess i'll have to mount some sails and get an electric fan to make her go

[lmagna]

Hi GAS

 

I used to do a lot of RC stuff and over the years accumulated a fair amount of stuff, including motors and drive gears etc. (It's called hoarding now days) I think I have several motors that may meet your needs to power your Blue Devil. No problems handling the 2" props direct drive. What I found in years past with the larger props, (3-4") was not getting the motors that I had to work but getting the universal joints to hold up when slamming the throttle from full ahead the full astern. The ears of the nylon dog bone connectors would sheer off almost every time! What I ended up doing was to make the dog bones out of brass with steel cross pins. I was able to make them using a hand drill and files. I used the collets made by Dumas on the motor and prop shafts. This arrangement has lasted for years on several ships.

I think I could supply you with motors that would be very well suited to your needs, (You would need to give me a little time to dig them out from storage and ship them to you) The dog bones and other stuff would be up to you.

 

Let me know by PM if you are interested.

 

Lou  

Edited January 9, 2018 by lmagna

[gluedandscrewed]

hi lou

just wondering if i'm on the right track? 2- 500 size direct drive motors, 7000 no load rpm at 6 volts, maybe a 1 3/4 inch prop,,would be the cheapest,,,not looking for hydroplane speeds just something realistic,, this thing is 6 feet long after all

Edited January 10, 2018 by gluedandscrewed

[lmagna]

Hi GNS

Let me see if I can do this right and make some sense for a change.

 

First off I have to say that I have been out of the electric RC stuff for a while and I must admit I am not sure what size a 500 motor is. If you are looking at 7000 RPM @6V then I will assume you are looking at RC car or possibly aircraft motors. If so then you are looking at high amperage motors that put out a lot of power in a small size but will draw a battery pack down pretty fast. 

 

The ship you are building is 6' long by 8", (?) with a draft of 3" (?) and like the Blue Devil model and not like the prototype is pretty much flat bottomed. I would have to look up the formula in my old stuff somewhere in the basement in a box but I want to say that you will need the ship to weigh somewhere in the 45-55 pound or more to float right. Getting that weight going and getting it stopped will take some power and as large a prop as you can fit. Since you need so much weight to float right anyway and you clearly have plenty of room why not think bigger and heavier?

 

Larger, higher voltage motors will draw far less current as a rule depending on what the motor was designed for. If you choose to use something like a starter motor for an automobile then you are again back in the high end draw short term use motor. But I have seen people use 12V windshield wiper motors successfully. Still a little high draw for my liking but doable. The motors I prefer are motors taken out of equipment like photocopiers and stuff like that. They tend to be reasonably high torque 18 or 24V high quality motors with low EMF properties, (Another important factor to consider in RC). They run quite well at 12V and can turn a surprisingly large prop without running up the amps. i personally like to use a motor that has about the same diameter or more than the prop you are going to drive. I also think that if you are able to provide 7000 RPM directly to the props that they would tend to cavitate and not provide thrust at all unless you back down on the throttle.

 

The other part of the system is to get away from the quick charge 7.5V battery packs and go to the gel cell batteries you can get for use in home alarm systems and back up systems. They are much easier to charge and much safer to use to say nothing about cost. If you know someone in the commercial fire alarm system business you can most often get batteries from them that have had to be pulled from alarm systems for liability/insurance reasons but still have tons of life in them for modeling uses. They are heavier but like I said you need the weight anyway. 

 

Again i need to remind you that i have been out of the hobby for a number of years and the largest ships I ever ran was a 4' ocean going tug and a longer but much shallower draft China River Gunboat, (Panay). But I do know of other people who have built in your size and displacement range and they did much the same as I described. If you want I could make a couple of calls and see what the modern uptake on the engineering aspect of large displacement hulls is and if it has changed from my day.

 

The offer for motors still stands if it turns out that they are what you are thinking about after all. 

Hope this is useful.

 

Lou

 

 

Edited January 11, 2018 by lmagna

[gluedandscrewed]

thanks lou,,

the motors are sold by harbor models as boat motors, brushed dc motors, i imagine the 7000 no load rpm  would be cut way down in the water, other than physical dimensions they offer no other specs, as for batteries i intend to go with a gel or even a sealed lead acid battery for the weight and amp/hr capacity, the boat is set for two motors and props

[lmagna]

Hi GAS

Thanks for the information on the motors you are looking at. They do seem to be somewhat milder than what I was thinking you were talking about. They should be able to drive the small props you are considering without much trouble. It would be nice if they published the amp rating but with the batteries you are considering you should still get OK running times.

 

I still think I would prefer larger motors and props for a ship this size but that may be a personal bias and has no place in proper design considerations. You are right in that these motors are certainly inexpensive, that's always a plus!

 

As always I will be following your progress with interest. Remember when you get it into the water the red side goes down! 

 

Lou

[gluedandscrewed]

keeping that red side down might be a trick lou,, the damn thing is long and skinnyyyy!! would like to go with the geared motors but just cant see paying more for the chinzy little gear box than the motor

[lmagna]

I agree, I have never seen a factory geared motor that I really liked the ratio they offered. I have done gear drives, belt drives, and chain drives and to be honest I prefer direct drive if possible. 

 

My only experience with the Blue Devil was the Lindberg one and you already know how that one turned out. Too top heavy on a narrow hull and flat bottomed all combined with no prior knowledge to speak of. It was only a matter of time. Your Blue Devil is much larger and with careful placing of all the heavy stuff low in the hull should be OK. I think you may have some power problems due to small props and motors and may have to think way ahead of the ship especially when going at full speed, but stay out of heavy weather and away from solid unmoving objects you should be OK.

 

One of my favorite ships I built many years ago was the British navel tug Storm King. It was about four feet long and somewhat narrow for what you would think a tug would be. Pretty much built it from scraps laying around the house as I was much younger and pretty much broke. Ran that boat in all kinds of weather for years, even did a little ice breaking with it once but that was a little hard on the hull so never did it again. I do have some old VHS tapes around here though showing me running in scale North Atlantic conditions. WOW was that fun! When you slow the speed of the movie down you can see the bow cutting through the higher waves and the flying water going over the bridge! And the rolling in the turns was something else! I would have given almost anything to have had one of the modern day VR cameras installed in the bridge and been able to be "On board" so to speak. I showed the footage to an old Coast Guard officer and all he said was "I've BEEN in weather like that! 

 

An even larger ship like yours will be impressive to watch doing destroyer like things with a high bow wave and water piled up at the stern. I do hope you have a place to run where you have plenty of room, as you have done a fantastic job of building and deserve to get the fun part afterward of watching your creation act like it's full sized counterpart.

 

Lou

[gluedandscrewed]

north atlantic conditions???yeah, i know about them,,11 days at 18 knots in january, rota spain to norfolk,,man, what a ride!!!! 40 foot seas all the way, anybody wants to feel like an inconsequential speck in the scheme of the universe they need to spend some time in the north atlantic in the winter!!!

Edited January 13, 2018 by gluedandscrewed

[lmagna]

Well this was MODEL North Atlantic. The waves were more like four or five INCHES, not 40 feet! But it was still fun and made for some very interesting movie footage. 

 

Lou

[gluedandscrewed]

i got your drift lou,, only wish my atlantic experience had been scale,, but i have to say it was an experience!!!! we were on a 20,000 ton uss san diego,,,i cant imagine the wild ride guys on a 3-4,000 ton tin can experienced,,, no roller coaster in the world can compare!!!!

[lmagna]

Well you could have been in Typhoon Cobra in 1944:

 

100 mph (87 kn; 45 m/s; 160 km/h) winds, very high seas and torrential rain, three destroyers capsized and sank, and 790 lives were lost. Nine other warships were damaged, and over 100 aircraft were wrecked or washed overboard; the aircraft carrier Monterey was forced to battle a serious fire that was caused by a plane hitting a bulkhead.

Story

Pictures

More

 

I read somewhere that this storm was one of the main reasons the US navy converted to the British hurricane style of closed bow on aircraft carriers.

 

Lou 

Edited January 14, 2018 by lmagna

[gluedandscrewed]

as we used to say, " back in the days when ships were ships and men were men"

 could be the reason, but i thought that most of the jeep carriers and light carriers were just conversions of other ship designs by addition of a flat top, regardless, you have to feel for the sailors on even todays high tech tin cans, mother nature can be a real MOTHER!!!

Edited January 15, 2018 by gluedandscrewed

[lmagna]

You are right. The escort carriers were converted hulls with a flight deck installed. The escort carriers were mostly converted cargo ships while the light carriers were normally converted cruiser or passenger ships. But in the US they were built open bowed with a gun platform under the flight deck at the bow and stern like the Japanese carriers. 

 

British carriers, including their escort carriers had the bow built up higher so that it met the underside of the flight deck. Possibly not a true hurricane bow like today's carriers but still much more weather resistant than the American and Japanese designs of WWII.

 

Lou