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1:24 Little Nellie Autogyro; WITH MOTORS!!
Topic Started: Dec 21 2013, 09:55 PM (953 Views)
AndyT
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Sound the klaxon twice and dive the Submarine!
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I saw these itsybitsy motors and had this idea ...................
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I just had to have a go and see if I could fit them into a 1:24 scale autogyro

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AndyT
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Sound the klaxon twice and dive the Submarine!
[ *  *  * ]
I had previously built a "What If" with Little Nellie converted for use with a Tuc-Tuc ....
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so I had some real hands on and from this I could see that this was going to be a VERY tight fit.

This motor was originally intended as a vibrator :omg:

Now calm down you dirty minded lot :slaphead:

... as a vibrator in a phone .... ok !!! .....

Anyway, its only 4mm wide and the main body is just 8mm long!
Now this gives it some distinct possibilities .....

Its so small, I was even thinking of installing it in this Micro drifters Bi-plane from the Disney movie "Planes"

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AndyT
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Sound the klaxon twice and dive the Submarine!
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I gradually increased the existing hole for the original shaft until I could get the body of the motor in and the bearing and shaft were above the plastic.
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Next I took the motor out and holding the top and bottom of the rotor head sections together, I drilled a new hole through the bottom to allow the base of the motor to sit flush and to allow wires to pass through.
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Edited by AndyT, Dec 21 2013, 10:51 PM.
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AndyT
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Sound the klaxon twice and dive the Submarine!
[ *  *  * ]
The original rotor was designed to spin in the head
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I would need to adapt it to suit the motor shaft, so I cut the lower section of the shaft off
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and then drilled a 0.5mm hole in the centre. As the shaft of the motor is 0.7mm I estimated that this would allow sufficient friction grip for the motor to be able to be directly pushed into the head.
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AndyT
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Sound the klaxon twice and dive the Submarine!
[ *  *  * ]
I carried on with the assembly until I got to the engine.

Normally the rear of this assembly has a lug that allows it to be attached to the frame.
It was not going to be possible to fit this, so I assembled the engine and then drilling from the front, gradually enlarged the existing opening till I got it to 4mm. to allow the motor to be slid in from the front.
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Please note!
Prior to the fitting of these motors, I have added longer wires to the motors and tested them with a 1.5v AA battery ~ they are very quiet but if you hold them up to our ear they sound just like a mosquito.

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AndyT
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Sound the klaxon twice and dive the Submarine!
[ *  *  * ]
I should have added, that before installing the motor it was necessary to remove the resilient rubber mounting and the off-set weight.

Resilient mountings are normally used to reduce the vibrations passed from a motor to the framework or hull. This was developed especially for the submarine service during WW2.

So this is unusual as the rubber used is very soft and accentuates the vibration caused by the offset weight in a phone to help the owner feel the vibrations but still ensures that the motor is still held firm in its intended position.
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AndyT
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Sound the klaxon twice and dive the Submarine!
[ *  *  * ]
First I sheath the soldered joints in heat-shrink tubing before routing it down through the air frame.

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I have used black wires as they will look like wiring looms within the frame of the model.
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You can see from the pics that I am using the fuel tank as a staging post for the wiring before it passes down into the base.
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Diesel Gypsy
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Somerset Bumpkin.
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Looking good there Mr T :thumbsup:
Isn't it time for your medication?? :whistle:
:popcorn: :popcorn:

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Harriet
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Advanced Member
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Nice one Mr T! :thumbsup:
:popcorn:
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peebeep
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Lots Of Trouble Usually Serious
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Excellent. If I were doing this I'd be a bit concerned that the rotating mass of the rotors could lead to them breaking off at the rotor head. I'd consider reinforcing them with brass rod or piano wire. The torque reaction could be quite considerable unless the model is well anchored.

peebeep
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AndyT
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Sound the klaxon twice and dive the Submarine!
[ *  *  * ]
Thanks Dave, H & Paul for the kind comments.
Yes the speed of the rotor will have to be carefully controlled, so I have two ways I can do this and either will work....

1st is to adjust the voltage to the motor through a potentiometer.

2nd is to use pulse width modulation with one of my Picaxe boards.
This turns the output on and off very fast which is programmed as "Duty" and "Cycles"

This is the same way in which you can vary the output or dim an LED.
LED's are either on or off but if you flash them really fast the eye is fooled into believing that they are dim.

The first is rather crude by comparison and uses quite allot of current and if I wanted to control the speed of the propeller and rotor would require two pots which would be nearly double the cost of the electronics. Size is also an issue, the wire wound multi turn potentiometers I would want to use are about twice the diameter of an AA battery

I was thinking of mounting the model on a tube so that it stood off the base and allow wiring to travel down the tube to the base that could also house the battery and electronics.
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foxy
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Happy modeler
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Now thats different Andy.
Like it.
:popcorn: :popcorn:

:OT: Merry Christmas :drink:

Cheers foxy :coolio:

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KallistiUk
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Advanced Member
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Where did you get these motors from?
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