Depth Cruiser

[KevinMC]

New product announcement: Depth Cruiser



After many iterations of design, development, and redesign (groan!) KMc Designs has added a pressure-based depth-keeping device to its product line:
Introducing the "Depth Cruiser".

In keeping with the design philosophy of other KMc Design products the Depth Cruiser is designed to be easy to install and just work quietly in the background. It requires the addition of a pressure pick-up tube to your existing installation, and plugs in "inline" between your receiver and bow-plane servo: No extra channels are required. Deriving its name from an operational similarity to the cruise control in your car, the Depth Cruiser uses a highly intuitive control interface - Use your bowplanes to get to the desired operating depth then let go of the stick, Depth Cruiser will assume control of the planes to hold that depth. In the same sortie Depth Cruiser can help you hold at periscope depth while confirming the ID of your target, then hold you at torpedo or missile-launch depth all without extra channels or any adjustments at the controller. From that same primary control stick Depth Cruiser can also be completely disabled, returning bowplane control to full manual control when you so wish.

For boats with retractable bowplanes, Depth Cruiser is fully compatible with the KMc Designs Bowplane Interlock.

Come see it in operation in Kevin's OSCAR II and even the tiny KILO at the 3rd Annual Carmel Fun Run on Aug 5/6/7. (Yes, there is room in even in the 1/144 scale KILO!) One lucky winner will also be able to snatch a Depth Cruiser from this year's raffle table so don't hold back on buying those raffle tickets!

The Depth Cruiser is also available immediately from KMc Design for $55USD. Contact by PM or email KevinMc.Electonics[at-sign]gmail.com.

[bob the builder]

Is there any reason that you couldn't connect the DC to a peristaltic pump or piston tank motor for static depth keeping?

[Guest]

I would think it would oscillate about a depth unless you can tune PD parameters to account for different boat designs.

[bob the builder]

Andy,

I guess I'm confused as to why the type of boat would make any difference. If the pressure switch is sensitive enough in the unit, I'd guess you'd get fairly static depth-keeping, provided the pump can keep up to the constant changes. I'd guess it would be working constantly, but I bet if you ran the output to an ESC, motor voltage would be low enough that the pump shouldn't overshoot the ideal state by too much before it needed to reverse.

I've ordered two to play around with and I'm pretty excited to see how they work. I'm thinking I'll try one in my current 48th scale Type VII build. That should hit the water mid next month if things go well...

[Guest]

Wetted surface area.

e.g. a LA class and typhoon of say equal size will sink or surface at different rates for the same amount of displacement reduction/increase.

How would the depth controller know how long to run a pump for to empty or fill a tank to maintain a set depth? For really good static depth control, you need to have measurements of not just the current pressure , but also the rate of change of pressure.

[JWLaRue]

How is this any different than a pitch controller 'knowing' when to return the dive plane to neutral?

-Jeff

[Guest]

Levellers need to be dialled in. Most controllers have a set of PD parameters preset and you can select between say three e.g. fine, medium and coarse.

Some levellers can be very finely tuned to the boats natural oscillation, but they're more involved in the adjustment process so most modellers prefer the simpler units, which are generally adequate for most purposes.

[KevinMC]

Is there any reason that you couldn't connect the DC to a peristaltic pump or piston tank motor for static depth keeping?

I'm not very optimistic about how well that would work "out of the box" without spending a lot of time at it and heavily optimizing the ballast tank; The control law in the Depth Cruiser was designed to work with a proportionally controlled servo/control plane implementation.

The problem with using it to drive a ballast tank is that tanks take a looooooong time to go from "dive" to "rise", unlike a servo which goes between those two extremes almost instantly. I agree with Andy that you'd likely run in to oscillation problems. I also think you'd also run into static/dynamic problems when you get underway unless you could "lock out" the controller from affecting the ballast tank when the boat's in motion.

Were you thinking of having one controller running a ballast tank, and a second one running bowplanes? Or was your thinking to just control the tank instead of the planes?

[bob the builder]

I was thinking just ballast tank. The APC would take care of the level while underway while the tank kept it at correct depth.

It was just a thought. I bet it would work (kinda sorta)

[salmon]

Bob,
It might with a small piston. As it is designed for this to work there needs to be forward motion. That way the front planes can work at adjusting depth.
Where this might work is for static or zero forward motion and maintain a depth. Such as firing a torpedo or launching a missile or just hovering, lurking waiting for the next target. Kevin, would this work?

[KevinMC]

There certainly is an opportunity for this to be made to work when you're static. (I still think you'll need to have a fast-acting tank that works in a proportional mode so when the DC commands "neutral" the tank assumes a half-full condition, and the boat will need to be trimmed so that this mid-filled tank results in neutral buoyancy.)

It's possible to get this scheme to work while underway as well, but there are so many forces at work that it will be a significant challenge to keep them all in check. It's not impossible, just not for the faint of heart. (But I have faith that Bob's up for the challenge!)

[Guest]

It has been done to plenty of times. The most recent version is by a John Robinson, a modeller over here in the UK who built a new piston tank control board for his Engel which uses mosfet h-bridges and features a dial a depth style system. That can hover the boat at a set depth.

[Guest]

http://www.modelboatmayhem.co.uk/forum/index.php/topic,52261.0.html