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Jul 06, 2017, 08:51 AM
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RCBoater's Avatar
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Question

How to build a working flight deck elevator?


I'm working on a 1/144 scale Casablanca class escort carrier. (See my USS Guadalcanal thread elsewhere in this forum.) I'd like to animate one of the flight deck elevators, so I'm looking for advice on the best way to do this.

The elevator will be about 3.5 inches square, and will have a plastic model with folded wings sitting on it.

One option I'm considering is some sort of endless cycle, with a simple on/off control via RC. When "on", the elevator slowly descends to the hangar deck, bottoms out, then rises back to the flight deck, then descends again, etc. I'm thinking having it cycle once every 30 to 60 seconds.
One way to implement this would be with a geared motor with a cam, that is mounted under the elevator. As the cam rotates, it would push the elevator up, then let it fall back down, etc.

Another option might be to use a servo and a 90 degree bellcrank, and just use a proportional channel to slowly move the elevator up and down from the transmitter by slowly moving the servo through the range of motion. While not "fire and forget", this option may be easier to construct, though it may be a little harder to tune the endpoints...

I'm thinking I should build the entire moving elevator unit as a module that is attached to the underside of the flight deck. It seems to me that this would be easier than trying to get everything aligned, if I had the mechanism in the hull and the elevator and track on the removeable flight deck.

Speaking of the elevator track, what's the best way to keep it level and aligned with the opening? I'm thinking I'd use posts (like a four poster bed) mounted in each corner, with a piece of plastic tube sliding over them. The elevator itself is them glued to the sliding tubes. I know it isn't "scale", but I don't think that will matter, as I envision only using the feature when the model is on the water. (I wouldn't display the model with the elevator in the down position, because there is no hangar deck in the model.

These are my ideas so far, but I figure I'd ask here. I'm looking for advice from anyone who has "been there, done that"......

-Bill
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Jul 06, 2017, 09:23 AM
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tghsmith's Avatar
Langley flight deck elevator.AVI (0 min 43 sec)
...
http://www.wmunderway.mysite.com/cgi...1264651288/105 William Blackmore's work,, He's having the fight with photo-bucket so you can't see the pics..
Jul 06, 2017, 09:27 AM
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CaptCB's Avatar

Rcb


It sounds like you are planning on r/c'ing the model.
Remember to cover any "open" hanger doors with clear plastic, to keep the water out, as models that size were never designed to be r/c.
Jul 06, 2017, 10:36 AM
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Quote:
Originally Posted by CaptCB
It sounds like you are planning on r/c'ing the model.
Remember to cover any "open" hanger doors with clear plastic, to keep the water out, as models that size were never designed to be r/c.
I think you misunderstood-- I'm building a 1/144 scale model, which is about 40 inches long, with a displacement of about 10 pounds. It is the Glynn Guest semi-scale model, from the plans in Model Boats. See my "USS Guadalcanal" build thread here in the forum...

That is good advice if you're converting a smaller plastic model though-- I'll have to remember that one.
Jul 06, 2017, 11:40 AM
Suspended Account
Think I would look at going with a worm gear type of system. Secure a pair of threaded standoffs to the corners of the elevator and drive them with a couple of threaded pushrods mounted verticle and driven by a single motor. That's the basic idea. The details I'll leave with you. However at 1/144 this may be a bit overkill.
Jul 06, 2017, 11:55 AM
Mmm, tugs...
patmat2350's Avatar
Scissors jack
Jul 07, 2017, 05:01 AM
20M northeast of Hell Mi
liljimmy's Avatar
Servo mounted to one side with a long arm under the elavator with a servo slower.use a switched channel from tx. If tx is computerized may be able to set end point. Or landing gear sequencer to control 3 different elevators.
R/C WWII LST door test(2) (1 min 20 sec)
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Jul 07, 2017, 05:13 AM
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Quote:
Originally Posted by patmat2350
Scissors jack
+1. Scissors jacks are usually a screw drive giving a straight vertical push. The screw drive can have a motor on one end, and be fitted with limit switches to stop it and diodes across the switches to allow it to drive out of the "dead" end.
Think about the old top loading VHS recorders.
Jul 07, 2017, 05:36 AM
Registered User
ServoCity's Servo Stretcher may be of use to you, allowing you to set both end points(seperately) as well as dial in the servo speed to your liking.
Jul 07, 2017, 07:21 AM
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tghsmith's Avatar
scissor jacks are actually a little more complicated , a single thread type has the drive screw moving in both planes (vertical and horiz) a more complicated unit using a drive screw with both left and right thread screw sections only has vertical movement during operation.. both types would require the drive motor to move with the unit or a flex drive set-up..
Jul 07, 2017, 10:58 AM
Registered User
A moving motor shouldn't be that big a deal, this is a 1:144 scale model so the motor will not be huge, about the size of a CD player tray drive motor. Thinking of which, anybody with a dead PC will probably have an otherwise useless old player deck lying around waiting to have its insides recycled.
Or, clambering right out of the box, ignoring arrangements with a winch ans string and pulleys and levers, how about borrowing something from the submarine lads? Guide the lift, raise it by inflating a balloon under it.
Jul 07, 2017, 01:28 PM
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The balloon is a clever idea, but it adds a lot of complication and expense-- an air tank, a solenoid-operated valve, etc.

But that does inspire me to look at another option-- perhaps a small water tank and a float. A simple water pump can fill a small tank, lifting the float under the elevator. The advantage there is you can fill, drain, fill, drain, to your hearts content. (As opposed to running out of air. )

I do see three issues with this idea:
1. Using a water tank would essentially be filling/emptying a ballast tank, that could affect the model's trim. But I think the tank could be made quite small- maybe a 3/4 inch diameter tube is all that would be needed, and the float only needs to be lifted about 2.5 inches max.
2. I can't use a switched (i.e. retracts) channel. I'd need a 3 position switch: fill-off-drain.
3. I'd also need a pump and a small ESC, with the accompanying current drain. Probably a minor concern, as it won't be running that often.

I did a sketch-up of a cam-based solution-- it isn't really going to work. The issue is range of motion, and the size of the cam. To get 2.5 inches of lift, I'd need a 3 inch diameter disk, with the rotation point (motor shaft) at a point about .5 inches in from the edge. This means the outside edge of the disk is scribing a circle that is 5 inches in diamter, and there isn't the room inside the hull for a circle that large.

So now I'm looking at alternatves-- I'm thinking KISS. A servo with a 3 inch arm that could rotate through a 90 degree arc could push the elevator up the track. That would allow me to use the 2-position retract switch on the radio. The only expense is an extra servo, and one of those servo speed reducers that the model airplane guys use to slow down the speed of retracts.
Last edited by RCBoater; Jul 07, 2017 at 01:38 PM.
Jul 07, 2017, 02:35 PM
George Jure
How about using a mini/micro stepper motor and controller? They are found ebay and are cheap. Mount the stepper motor vertically with linkage connected to the elevator.
George
Jul 07, 2017, 03:05 PM
Mopar Musclecar fanatic
xx29l9's Avatar
Don't over think this and make it too complicated. You can do this with a simple servo and 2 gears and adjustments on your transmitter if needed. I'm all for creative solutions....but yikes.

Bob
Last edited by xx29l9; Jul 07, 2017 at 06:10 PM.


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