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New Engel 212 build.

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Re: New Engel 212 build.

Postby Sub culture » Sat Mar 19, 2011 11:51 am

Tried ballast shifting?
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Re: New Engel 212 build.

Postby JWLaRue » Sat Mar 19, 2011 12:08 pm

Sub culture wrote:Tried ballast shifting?

Of course. Static ballast shifting only takes you so far.....in fact it only changes the single point at which things balance out for a given speed.

I am seriously considering adding a servo controlled moveable weight (which could be the battery)....

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Re: New Engel 212 build.

Postby Sub culture » Sat Mar 19, 2011 1:12 pm

A servo controlled battery shifter will work well.

Most pictures I've seen of 1:1 Seehunds show them to be trimmed low at the stern. This probably helped the boats handling on the surface.

I would think they would then trim level underwater, so this can be used to your advantage with a single piston tank system, and I would hazard a guess that's how you have things set-up at the moment?

Interestingly Rick Palumbo had issues with the handling of his little 1/22 Seehund kit, and ended up putting a fixed hydrovane mounted in the kort nozzle set with a bit of down angle.

Also of interest is the splendid little 1/35th scale Seehund kit by Bronco models. This appears to me moulded in such a way that the angle of the propshaft looks like it has a slight downthrust angle. Not sure if this how the originals were, or a moulding anomaly. The kit looks very accurate in all other respects.
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Re: New Engel 212 build.

Postby JWLaRue » Sat Mar 19, 2011 1:46 pm

So this is where having actually built and operated a Seehund helps.

It isn't possible to have a correct trim underwater for all speeds as the shape of the hull imparts hydrodynamic lift. I do have the static trim set to allow a good underwater trim for a given speed, but I want more flexibility in actual operations....especially once the torpedoes are made operational. :)

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Re: New Engel 212 build.

Postby Sub culture » Sat Mar 19, 2011 2:14 pm

I built a Seehund. It was an earlier moulding, not very accurate at all. Never suffered from problems described, but my one never went very fast- is your boat quite nippy?
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Re: New Engel 212 build.

Postby JWLaRue » Sat Mar 19, 2011 2:39 pm

Let's just say that there is extra top-end speed available if warranted. :)

My preference is to operate at scale-like speeds, but that still covers a good range of speeds.

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Re: New Engel 212 build.

Postby Bigdave » Sat Mar 26, 2011 1:00 pm

I installed the new Engel Proportional ballast controller in the 212.
It took some trial and error and some modification to get it to fit and work.
But it works quite well.
I do not seem to be getting any glitching now.
I also installed a rotary control in one of the S/W expansion holes on my Multiplex radio.
It took a bit of cutting on the inside to get it to fit as the S/W would have been much smaller that the pot.
But now I get about 320 deg of travel on the control making for a much finer adjustment on the piston.
I will add some markings around the knob to give me basic depth points.
This should work out well. BD.
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Re: New Engel 212 build.

Postby roedj » Sat Mar 26, 2011 4:18 pm

Bigdave wrote:But now I get about 320 deg of travel on the control making for a much finer adjustment on the piston.
I will add some markings around the knob to give me basic depth points.
This should work out well. BD.


BD,

Please explain your thinking here. I can understand how changing the volume of water in the Engle cylinder changes the density/buoyancy of the sub to allow it to rise or sink at a certain rate but do not understand how you can set a "depth point".

Thanks for your time,

Dan
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Re: New Engel 212 build.

Postby JWLaRue » Sat Mar 26, 2011 8:21 pm

What BD is describing is a direct result of using the new Engel piston controller. Operationally it's the same as the unit in my Seehund.

Here's how it works:
    - The electronic module uses a Hall effect sensor to count revolutions of the main piston jackscrew gear.
    - Magnets are glued to the gear, which is what triggers the sensor.
    - The module then learns where the two endpoints are (full and empty) and how many revolutions of the main gear it takes to go from one extreme to the other.
    - This then allows the transmitter to control the piston as if it were a (linear) servo, yielding absolutely repeatable positioning of the piston and thus the amount of water in the piston.
    - By marking various points on the control pot, you can dial to the exact ballast volume that you desire.
    - I call this "Dial-a-Depth". :)
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Re: New Engel 212 build.

Postby Bigdave » Sat Mar 26, 2011 10:16 pm

Great explanation Jeff. :D
I will add that is why I said basic depth points.
No depth points are exact and they will vary from water to water. It will just give me an indication of where the sub should basically be at a given dial position.
It will be fun to experiment with. BD.
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Re: New Engel 212 build.

Postby JWLaRue » Sat Mar 26, 2011 10:29 pm

Thanks, BD. And your point about basic depth points is a very important one. Whenever I run my Seehund, I always do a test to see where the transmitter control puts the sub at proper submerged depth. Once I know that it tells me the 'offset' I need to run the sub at any given depth for that day's run.

Gotta love "Dial-a-Depth"!

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Re: New Engel 212 build.

Postby roedj » Sun Mar 27, 2011 3:40 am

Jeff & BD,

Thanks for the reply but with all due respect I still don't understand the theory or practice. Here's why:

1) A sub rises or falls in the water as a function of its overall density with respect to the density of the surrounding water. If the sub is more dense, the sub sinks. If the sub's density is less, it rises. If it's the same it does neither and we say it's neutrally buoyant. Obviously, I'm only talking about a static situation here and not diving or surfacing because of dynamic forces such as those caused by diving planes.

2) If we can agree on 1) then it follows that the amount of water in the cylinder changes the overall density of the sub to cause it to rise or fall at a certain rate but not to go to a certain depth. Given that the density of the water is probably the same for a depth of 1 to 5 feet for most of our diving situations, the overall density of the sub cannot be used to set its depth but only its rate of rise or fall. In other words, the sub has no way of "knowing" whether it's at 1 foot or 5 feet of depth based solely on its density. To my knowledge (always a risk) the only way to "set" a depth is to measure the surrounding hydrostatic pressure and adjust the depth to a desired pressure.

If Engle has come up with a way for overall density of the sub to set its depth it would be a real breakthrough. Please elaborate.

Thanks again,

Dan
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Re: New Engel 212 build.

Postby Bigdave » Sun Mar 27, 2011 9:20 am

Dan,
Me thinks you are confusing theory mumbo-jumbo with model sub real world operation.
In theory you are correct. But even though the model is moving up or down at times it will appear to be at a set point and hovering.
I know it is not actually hovering and is in real life decending at a slow rate, but it seems like a hover.
I think you are trying to read more into it than it is.
As they say(who ever they are)it is what is is.
It is just a proportional controlled piston tank.
You are still controlling the depth with "guestimation". It just makes it a little easier. BD.
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Re: New Engel 212 build.

Postby Bigdave » Sun Mar 27, 2011 9:29 am

BTW-Jeff,
I was thinking (scary thought) :oops: I may make a ring for the base of the knob that can be turned to as you say dial in the depth point of the day. :wink:
Lets say decks a wash.
Sort of like a Little orphan Annie decoder ring. Ha!! :lol:
I take the sub down to that point and then adjust the ring to that point, it should get me a fudge factor for different waters. :mrgreen:
I was think of that yesterday and it sounds like you do the same thing. Very cool!! BD.

PS!! I will call the gizmo "Dial-a-depth" I like that!! 8) 8) 8) :D
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Re: New Engel 212 build.

Postby fgroza » Sun Mar 27, 2011 9:47 am

Dave,
Does the fact that you have 2 magnets rather than 4 effect anything??? As I see it, the hall sensor still counts, just 1/2 of what it is supposed to count. As long as it knows the count for a certain hover spot, it should not really matter weather all of the magnets are on the gear,is this right?
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