Technical, Techniques, Hints, and Tips > Microprocessor control
T.A.R.G.E.T - Rotating Seven gun turrets?
Bob K:
A technical quandary. How to simultaneously rotate seven main armament gun turrets.
Some of you may guess what ship this is for.
To get more than 180 degrees rotation on a turret I will need a servo plus a control arm to increase the angle over the normal of about 90 degrees. It would be nice to slow the rotation down, if possible.
It may be possible to rotate two adjacent turrets from one servo by adding linkages, but trying to add enough servos to a single receiver channel will be far too much load for the Rx, even with splitter leads which do not reduce the channel loading.
Any ideas ?
Tug-Kenny RIP:
Two things spring to mind here with your question, Bob.
Would this normally be seen in action on the real ship and also how close are they together ?
My first reaction was a rubber drive belt. Is this any good. ?
ken
Bob K:
Thanks Ken.
Seven centreline turrets spread along around four and a half feet of a seven foot dreadnaught, made more complicated by my needing to split the hull in half for transport. 3 in the front half, 4 in the rear.
I realise that turrets do not train in exact unison, but achieving that effect may be a bridge too far. ie: building in short time delays.
John W E:
:-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) :-)) %%
Obviously there are going to be several ways to do the movement you require of the gun turrets - I can suggest a couple of ways I achieved this on 2 or 3 models - the first way I did it:
on HMS Ajax - I had 3 old Futaba Servos (they were the very old ones) which I stripped the electronics from and this left only the motor and the gearing. I also removed the physical stops from the plastic casings of the servos - so that the 3 servos could rotate. Then I purchased a new Futaba servo, opened it, and soldered onto it 2 fly-lead wires from the contacts of the motor. These 2 fly-leads from this servo, which was to become the main lead servo - were wired up to the three old servos in parallel, so, basically the 3 servo motors would mimic what the first brand new servo would do. Then, the other thing I had to do was to modify the new servo by taking the variable resistance pot out and adding 2 resistors. This isn't as complicated as it sounds and there are plenty of videos on YouTube, which show you how to do this. Each servo was mounted underneath a gun turret - the only problem with this is that sometimes the gun turrets do not line up on the centre line.
the second way I did it on HMS Exeter was I purchased 2 servo stretchers from Technobots and 1 from ACTion: These were mounted obviously in the hull and connected to 3 standard servos, which in turn were mounted underneath each individual turret. This was the easiest solution I have found, with the least problems.
The bugbear is (and it doesn't matter which system you use) the low speed of the turn of the turrets tends to produce a jerky movement.
If you look at my HMS Exeter build there is a section there where the turret build is explained.
http://www.modelboatmayhem.co.uk/forum/index.php/topic,33734.75.html
john
Bob K:
Lovely build. Very interesting :-))
But how to I couple seven servos to one receiver channel ?
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