1/200 USS Nimitz

[Fliger747]

Song:

Now I can see that we will have some opportunity to view the aircraft in the hangar deck. Quite an ambitious project with all the lighting. I am guessing that the LED's don't produce too much heat, though 200W is a very large rectifier!

You keep surprising us with your traditional and non traditional mix of creative talents!

Regards: Tom

[Goodwood]

Bloody hell this is epic. Can't wait to see what marvelous miniature miracles you manufacture next!

[Song Jung Gun]

Thank you,Tom and Sean!
It's gallery deck of starboard side.
It is suppoted 1mm rectiangular rod under the panel.
Song

[DrPR]

My initial reaction was that a 200 Watt power supply is overkill. But then I did the math.

200 Watts @ 12 Volts = 16.6 Amps

I don't know what LEDs Song is using, but 25 milliamps used to be a common current draw for fairly bright LEDs. A series 470 ohm resistor would be used (assuming a 3V drop across the LED) to limit current to 0.025 A. With a current of 0.025 A and a voltage drop across the resistor and LED of 12 V, the power loss in the resistor/LED will be 0.3 Watt.

16.6/0.3 = 55

So the power supply will drive about 55 ordinary LEDs at 0.025 A. I counted 52 white LEDs and 9 red LEDs in the photos Song posted. Since the white and red LEDs are not on at the same time, the 200 Watt supply is adequate for the job. But it looks to me as if he is using more than one panel of LEDs.

Since the assembly is mostly polystyrene, and this material is relatively soft and susceptible to melting, it will be necessary to provide some type of cooling to dissipate the 200 Watts without getting distortion of the plastic. Think of the heat of two 100 Watt incandescent bulbs in the small hanger space.

You can use larger series resistors to reduce the current through the LEDs, allowing more LEDs to be used with the 200W power supply. Some of the newer LEDs produce an extraordinary (by past standards) amount of light. By selecting LEDs that are very bright at 25 milliamps you can reduce the current and still get enough light for good illumination.

So, having done this quick calculation, I wonder what current Song is using in the LEDs and how many total LEDs?

Phil

[Song Jung Gun]

Dear Phil!
I thank your recomendations.
Yes It is too big 12V 200Watt PS.
There are 165 LED(0.5watt) in the hangar. 0.5*165=82.5watt
I will add some more LEDs flight deck and the other shelters.
It will be 30~40watt expected.
So,82.5+30~40=112.5~122.5watt.
The large capacity PS has no problems.The smaller has much problems.
The problem is the heat of lightings.There are no heatsink no ventilation....
The solution is reduce ampere of lightings.
I will insert dimmer(12V30A) PS between lightings.
I expect it will reduce brightness and heat of LED.
Thank you again.
Best Regards; Song

[Song Jung Gun]

Hi,gentlemen!
It is gallerydeck of portside.
Song

[DrPR]

Song,

There are ways to reduce the heat generated. In my earlier example I used a current limiting resistor for each LED. Each resistor/LED "leg" drew power of 12V x LED current.

You can wire several LEDs in series with a single resistor. This way each "leg" still draws power of 12V x LED current, but you don't need as many "legs."

Power = Voltage x Amperage. If the LED current is 0.025 Amperes and the Voltage drop is 12 V, the power is 12 x 0.025 = 0.3 Watts.

If you used a single resistor for each LED, the power per LED would be 0.3 Watts. But if you have three LEDs in series with the current limiting resistor the power for each LED is equivalent to 0.3/3 = 0.1 Watt.

****

You can reduce the heat inside the hull by placing the 12 V power supply outside the hull and then running the 12V power into the hull. Some people mount the hull on two decorative posts and run the power in through these.

If the heat builds up in the hull you might try placing 12V fans inside the hull to circulate air through the hanger deck.

****

Most modelers give no thought to thermal effects in their models. If they are static indoor display models heat is rarely a problem. But RC models operated outdoors present real problems.

I recall a fellow who built a 1:72 aircraft carrier with a wooden frame and plastic shell and decks. The flight deck was about three meters long, and was made of plastic. Plastics have a much greater coefficient of thermal expansion than wood. So when heated they expand faster than wood.

Sunlight produces about 940 Watts per square meter when the sun is directly overhead on a clear day. The flight deck of the carrier was about three square meters and absorbed about 2700 Watts of heat. The plastic flight deck expanded about 5 mm (1/4 inch) lengthwise with a 20C temperature rise, but the wood expanded very little. The flight deck bowed up several centimeters in the center, and pieces of plastic along the sides popped loose from the wood frame and bowed out quite a bit!

Phil

[Song Jung Gun]

Dear Phil!
Thank you, your calculation of LED wattage current.
I will install power supply and some switch and control devices under the hull (base).
I put dimmer ps between loads.
That control voltage and adjust brightness of LEDs.
The 2nd picture is uncontrlled light.
The third picture is contrlled by dimmer.
I measure temperature of LED. It is 1.5~1.9 degree centigrade higher than surround.
The result is acceptable.
Regards Song

[Song Jung Gun]

Hi,gentlmen!
I've built guide rails of elevator. And some panels between door frame and elevator when it is lower position.
The shape of these are different each of them.
It is required standard.
Song

[Song Jung Gun]

Hi,gentlemen!
I've made structure of portside rear the #4 elevator.
They called "Finger".
Song

[Iceman 29]

Honestly, you'd think you were in that hangar!

Bravo Song!

[Fliger747]

Yes! Absolutely convincing!

Regards: Tom

[Song Jung Gun]

Thank you,Tom and Pascal!
I've made opening edges and fairleads.
Song

[Fliger747]

Song:

A wonderful marriage of different materials to form different objects! You have obviously carefully considered the best method to replicate each form! Though with your meticulous craftsmanship I am confident you could have achieved a good result, I think you have raised your results to an new level!

Regards: Tom

[Song Jung Gun]

[quote="Fliger747"]Song:

A wonderful marriage of different materials to form different objects! You have obviously carefully considered the best method to replicate each form! Though with your meticulous craftsmanship I am confident you could have achieved a good result, I think you have raised your results to an new level!

Regards: Tom[/quo
Dear Tom!
You make me a master but I am just common.
I usually built traditional way using wood or plastic by hand.
Thank you always!
Best Regards; Song

[Song Jung Gun]

Hi, gentlemen!
I've made H beams on the starboard.
And I 've made special structure in the #1 elevator area.
Song

[mikegr]

fantastic

[Song Jung Gun]

fantastic

Yhank you,mike!

[Song Jung Gun]

Hi,gentlemen!
I've built 2 rooms in the port side.
Song

[Fliger747]

Song:

On such a large (1:1 scale) warship the number of small details are endless! Your ship requires careful planning in it's construction to access the placement of completed sub assemblies. There was a story about a new officer getting to know the carrier he was aboard, and he wondered what a certain area was but could find no access. As it turned out they ended up cutting an access and discovered a completely equipped machine shop, with no door!

Regards: Tom