Akula 1/144 Scratch built

[MFR1964]

NOOOOOOOOOOOO!!!!!!, finish your Nautilus!!!!

[He Who Shall Not Be Named]

Bart! I want one of those kits. Let's work out a trade or somth'n!

M

[MFR1964]

Bart,

Did you made those copper templates yourself?

Manfred.

[bwi 971]

Half a day work......she is turning into a real sub now....slow but steady

Grtz,
Bart

[bwi 971]

Thks David…......you taught me well…......the stencil prep work pays off too.

Grtz,
Bart

[He Who Shall Not Be Named]

Good work, sir!

M

[bwi 971]

Scribing, at last.
Started with the bottom flood-drain holes.
Nevertheless I have to open them up afterwards I scribe them first for practice purpose.
All went well, and I’m pleased with the result, pictures showing scribed lines without cleaning or touchup.

Grtz,
Bart

[bwi 971]

Bart,

By DC, you mean your depth controller i assume, have also one inside the type VII, it's connected to the front diveplanes, so when the depth is reached it will stear up the divingplanes, so limiting the depth i can reach with my boat, it can be overruled with a switch when driving in clear water.

Manfred.

It's a sort of depth controller Manfred it will keep my boat at a constant depth, no limitations in depth and it will not interfere when I adjust my depth. But when active it will help me to maintain my depth when my stick is in neutral position. I’m very keen to see how it performs.


Grtz,
Bart

[MFR1964]

Bart,

By DC, you mean your depth controller i assume, have also one inside the type VII, it's connected to the front diveplanes, so when the depth is reached it will stear up the divingplanes, so limiting the depth i can reach with my boat, it can be overruled with a switch when driving in clear water.

Manfred.

[bwi 971]

The DC needs a pressure pickup tube the requirements are:

• It must run vertically for at least 2 inches at the end
• Open end to be as for as possible to the bow.

The pickup tube is made out 3/32 brass tube. Soldering the tubes at an 90 degree angle would not be strong enough so I made an corner piece.
The right angle corner piece is made off 2 pieces of 2,5mm aluminum. Temporary spot glued together to drill the holes and permanently glued together when the tubes were inserted.









The bulkhead pass through is made of an aluminum rod turned down to 5mm and provided with an 2,4mm hole (3/32”). A hole of 5,5mm was drilled into the fwd bulkhead and the stuffing box was glued in the bulkhead with rtv silicone.





When I know the exact position of the SD in the AKULA the pickup tube will be cut to the length needed and glued in the stuffing box with RTV silicone.







Grtz,
Bart

[MFR1964]

No problem Bart, i hope we can meet, i'll be there for sure, taking the active fleet with me, you still have a couple of months for getting her running, no sweat.

Manfred.

[bwi 971]

Bart,<br />
<br />
<br />
First start on a low level sensitivity and work your way up.<br />
The moment you're getting jitter is the moment harmonics sets in, you can search like hell, but that's wasted time, it can be anything, starting with vibration from your drivetrain, electronic noise, voltage variations from your BEC, or much more.<br />
All you can do is using some soft rubber underneath your ADF and keep some slack into your cables, when wrapped tight they also transport vibrations to your ADF, when done, follow the same path with setting the sensitivity higher and higher, on more tip, place your SD on a soft surface, imitating that you are floating in the water.<br />
When the jitter starts again,go one step back, and see for the result, this setting will be the highest you can run, beware, in the water it can be totally different, but that you have to test live.<br />
<br />
Manfred.

Thks Manfred....if I can't get it right I will be pulling your sleeve at the subsail this year.....I hope I get her up and running for the event.

grtz,
Bart

[bwi 971]

Interesting stuff David.

I have Norbert bruggen's book "technik der u-boot modele" I studied it in the years before I actually started the akula project. I think it's a must have for beginners. All the things you must know are described in it. Even how to make angle keepers and depth keepers yourself.

He also mentioned the pendulum with two phototransistors and a diode, filled with oil to damp the oscillation. Wonderful stuff.

Probably everybody in this house has it in their collection.

grtz,
Bart

[He Who Shall Not Be Named]

An observation about the angle-keeper 'jitter' issue. First my credentials:







I've operated a wide array of mechanical and 'solid state' sensor based angle-keepers. I've even constructed my own by modifying helicopter rate gyro amplifiers -- as instructed by Skip Assay. I know my way around these things. The jitters experienced -- once all possible electrical 'noise' has been mitigated -- is a consequence of the non-mechanical sensors used today -- most are air-bag accelerometers that measure the direction of movement and amount of acceleration of air within. I suspect that their velocity measurement is not linear to the change observed as a consequence of velocity change -- I bet if you scoped out these little accelerometer outputs you would find spikes rather than curves following velocity changes to the sensor. Over time those spikes translate to reasonable response curves. Kevin: Help!

These types (all the rage today) all get the jitters. Don't sweat it -- once the model is in the water, the water acts as a perfect damper (Ron Perrott's beautiful little SailCon featured a pendulum damped in an oil bath -- SMOOOOOTH!) and you'll see less jitter in the stern planes once you let it go.

The old mechanical (pendulum and liquid) angle keepers operate smooth as silk and only jitter because of servo, motor, and pump vibrations.

David

[MFR1964]

Bart,<br />
<br />
<br />
First start on a low level sensitivity and work your way up.<br />
The moment you're getting jitter is the moment harmonics sets in, you can search like hell, but that's wasted time, it can be anything, starting with vibration from your drivetrain, electronic noise, voltage variations from your BEC, or much more.<br />
All you can do is using some soft rubber underneath your ADF and keep some slack into your cables, when wrapped tight they also transport vibrations to your ADF, when done, follow the same path with setting the sensitivity higher and higher, on more tip, place your SD on a soft surface, imitating that you are floating in the water.<br />
When the jitter starts again,go one step back, and see for the result, this setting will be the highest you can run, beware, in the water it can be totally different, but that you have to test live.<br />
<br />
Manfred.