Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Bob K]

Full Length

Had a bit of a scare this morning, putting the two halves back together after the deck-working.  The tubes were a bit tight, unusually, and then it all jammed together.   
Yipes !  Carefully prised the hulls apart I then checked the fit of each tube, which had slid together so well before.
The fit of the tubes is so close that even a little dust from the filing was enough to cause a jam.  Bottle brush on a wire. a bit of light oil and they slide nicely again.  I am going to have to watch that for that in future.

Anyway, here is how she looks in full length glory with the decks placed on.  I am tempted to take Agincourt to the Black Park Regatta on Sunday, just for fun, with my little Royal Marine armed trawler on top for a same scale comparison.  You could almost land an F35B on that, except for the big holes.
After commissioning Black Park Lake will become her home port.




The blind M5 nut inserts have just arrived, so I can mount the toggle latch. 
A tad over seven feet.  Yes, I am nuts.

[ballastanksian]

I think every hobbyist is a little bit mad, or we wouldn't do these things that slightly frighten us as well as excite us.

She's looking good Bob. Regarding the tubes, there would be little point in having such a system if it was sloppy. so don't fret, youv'e got it covered 

[Bob K]

Lots going on, so I will just itemise various parallel developments.

First Outing

Agincourt had her first outing on Sunday.  Black Park MBC Regatta.  My first chance to check the logistics of transport and lakeside assembly.  My Silver Cross push chair will need a special double-decker platform to carry it properly.  Two bases 500 mm apart, the top platform on four shower rail pillars that can be assembled in the car park.  However no double trips back and forth to the car park were required.



Next Outing

This weekend the ship will travel to Dean’s Marine for their Open Days.  I hope to get the prop shafts and propellers so I can start installing the drive system, with the four big Buhler motors sitting in my workshop.

Pump System

In the mean time I have started on the pumping system to load and vent 10 Kg of water ballast.  This is to reduce "dry" lift weight at the waters edge.  I have the four pumps, rated at 4 litres per minute, one to pump in. one out, in each hull half.  I have ordered four small water level switches to turn each pump off when it reaches limit.  Two inlet filters (pond weed!) using car fuel filters.  Inlets to be just under the “dry” waterline, outlets to replicate bilge pump outlets.  The system will be operated from a single Rx channel with a servo, cam, and two microswitches.  In & out.

Gun Control

I am deeply indebted to both Geoff (Iron Duke gun smoke) and C-3PO (Arduino fame) for their time and kind assistance in my trying to incorporate both their systems together.  It will be challenging to try to incorporate both automatic turret bearing and gun smoke together, especially the requirements of fitting both systems into the same barbettes.

It is always good to have multiple aspects to work on in parallel, to avoid design hold ups.

Fitting the numerous batteries required will be interesting as the internal stainless tubes make things interesting.

[derekwarner]

Is this her projected waterline Bob?...................

With the water ballast discharges 'to replicate bilge pump outlets' so naturally these are xx mm above the ballasted waterline

Will you be placing the pump suctions in a ballast tank well?......this is a small in say [say 20mm cubic] well below the ballast tank proper and logistically  placed possibly aft in each tank to enable a slight [physical] trim to aft when she is in the water to ensure  all of the water ballast in the tank is emptied and only the small volume of the 20mm well remains below the pump suction

Will you further have manual emergency drain valve/s to each tank?.......[these fish aquarium brass plug format from e-bay are extremelyin expensive ......approx. 3mm bore.....come in all different configurations.....I have them in my boiler water make up system]

Derek

[Bob K]

Derek:  You are on the ball as always.  Yes, there are going to be technical issues with this ballast system that I am trying to resolve.  That is the waterline correctly marked in your picture (very nicely drawn).  First issue is I am not using self priming pumps (rare as hens teeth) so about a cm of water may be left inside.  No big weight issue.  The need to be able to slide the hull halves together precludes having pump wells below the otherwise flat keel.

I plan to have a hand pump handy in case of failure to pump out.  I am trying to avoid kneeling down on the bank.  I need to be careful in positioning the water inlets so they are not vulnerable to “coming alongside” damage.  Perhaps just where the hull section starts to curve under.  The “tanks” are between pairs of full height bulkheads.  Pipes are 8 mm bore.  Outlets will be up-and-over, ending in several 3 mm through-hull vents above the full displacement waterline.

First stage is to acquire the parts then do some tests in the bath.  Half hulls will easily fit in the bath, one at a time.

[Bob K]

Props & Shafts

An interesting stage this, mounting the shafts props and motors.  With a single shaft it is relatively straightforward, even with twin shafts.  However I am finding that four presents a whole new complexity to getting it right. 

Start with the inner pair whilst treating it as a two shaft system.   Ended up with 65 mm long slots, prop clearances and motor positions checked, leaving a little clearance for positional adjustments.  Next the outer slots, taking into account the amount the outer props are forward of the inners.  Hull at a slightly steeper angle going through.
Measuring the angle where the shaft outer goes through, and knowing the diameter, you can calculate the length of the slot required.  Best to start with a reasonable fit.



A temporary “A” frame using prop radius plus a bit, then you can look at where the motors lie.  I use a close fitting tube for initial shaft to motor alignment.  Heavy duty couplers from Dean’s have a large rubber “X” block between the drive spigots.  No noise.



Next will be figuring out the best method of accurately mounting the four motors.  Axial alignment is most important, then keeping possible angles close to zero in three planes.

[Akira]

I am sure that you know of this technique, but I'll throw it out there anyhow. Once your stuffing boxes are glassed into place and you have determined your motor mounting location, using telescoping brass or any other rigid tubing ( you can use your prop shaft as well) make an adapter to go from your shaft size to your motor's shaft size.  With your "prop shaft" in place along with your adapter, shim your motor to the point of least resistance,ie, being able to spin your prop shaft and motor most easily. When your have found the "sweet" spot, fixed your motor into place, checking that the "sweet" spot remains. remove your alignment shaft, insert your prop shaft with your universal and you should be good to go.
I hope this makes sense.
Jonathan

[derekwarner]

Hullo Bob......the slots in the hull are only cosmetic and of lower consequence than any other aspect of the shaft installations

Do the plans offer a profile line set at the relative position of each propeller in both inner & outer pairs?

Do they provide the same information relative to the lay and angle of the shaft centres inboard closer to the position of the motors?

If so, do they provide sufficient dimensional detail to produce temporary wooden jigs?...

There is a tug build thread on MBM....I will find it ......it provides a brilliantly accurate simple method of such alignment.....

Here you go....http://www.modelboatmayhem.co.uk/forum/index.php/topic,57583.msg600068.html#msg600068

Look back at this build ...it will help......Derek

[Bob K]

Do the plans offer a profile line set at the relative position of each propeller in both inner & outer pairs?

No.  Three huge detailed sheets with nothing on props and shafts.  I am having to rely on a couple of old photos and a few small line drawings from Google (which are inconsistent.)

The shafts need to as near horizontal as practical, consistent with motor mounting and keeping the props within the keel / hull profile.  I did read that thread recommended (Korts) but it does not help that much.  Thank you anyway.  Neat job!
 
Next I will be making up some dummy "A" frames to locate the outer shaft ends, then turning it all over to work out motors positioning and mounting.  Plus I will have to shorten both inner & outer shafts, by different amounts.
I am sure just about everyone has done this, as I have several times, I just wish there was a more logical modus operandi than fit as you go.  The cutouts need to be fairly accurate to stand any chance of getting the rest right.

[raflaunches]

I must admit that I'm at the same stage with my Invincible project. The inner shafts were relatively easy to set up but the outer shafts have yet to be fitted due to vagueness of the drawings and the fact that I'm using a drive belt from the inner shafts. I've used as a basis the measurements from the Dreadnought and then staggered the shafts to match the side profile of Invincible. Whilst I'm away in Sardinia Steve is ordering the drive belts and cogs from SHG so hopefully when I return in 12 days time I'll get to fit the outer shafts.

[Bob K]

Nick:  I saw your inner shafts installed at Dean's.  You did say then you were belt-driving the outers.  I am following your build with great interest.  Best wishes for Sardinia.

[Bob K]

Motors & Shafts

This really is becoming a precision Chinese puzzle, being more dictated by getting the huge motors in, with the outboard pair behind the inboards, plus allowing for the diameter of the large couplings alongside adjacent motors.  With a ‘normal’ mount of one or two shafts you have a reasonably flat inner hull area for mounting. These are varying ways up the hull curve.

Some compromises necessary.  Shafts are angled slightly more downwards than ideal.  The amount of shaft inner protruding under the hull is less than scale due to the angles.  At least I can get them almost parallel to each other.

Leading edges of the two inch diameter motors touch the hull profile.  Traditional fixing brackets are out of the question, so I am moulding bases using air drying Fimo clay, packing it underneath. Air drying because I can’t put it in the oven, but it is enough to form the shape under the slightly inclined motors.  Clay bases will be epoxied in, epoxied over, and fixing straps added. 

At this stage I am using 4 mm ID tubes for shaft alignment, cut to length to suit the couplings and fittings.   The complete drive system extends 60 cm into the hull.


Motor mount bases using air drying clay


and managed to get the shafts parallel


Shafts will be cut to length when mountings done, and "A" frames added.

[derekwarner]

Bob...after you have your individual motor axis and shaft alignments established, don't forget those humble Nitrile O-Rings

1/8" section O-Rings squeezed into an ellipse......a few Superglue tacks to hold the shape  & you have a very tidy complete Coffer Dam to flood the epoxy ......

Naturally one shaft at a time with the mean axis @ 6:00 o'clock 

Derek

[Bob K]

Good idea Derek.  Thank you

[Tug-Kenny RIP]

I agree, that's a good idea Derek. It was something that was always needed for a tidy job.  Any before and after pictures ? to show it doing the job.

ken

[ballastanksian]

While I reckon the 'O' ring idea is elegant and naturally very simple to set up, I would go down the route some others have and that is to build styrene coffer dams so you can enclose a greater area of the hole and tube in resin especially for a monster build 

I think the 'O' ring idea is brilliant for smaller models where the forces on the joint are less noticable in collisions/torque situations. If folks use the rings for larger models then I sit corrected and impressed 

[Liverbudgie2]

Why are you using such large and powerful motors? Each one of those will, probably, swing a  two inch prop with ease. Surly a physically smaller, higher revving  motor would achieve the same purpose, this then would in all probability, allow you to lower the motor and so reduce the shaft angle.

LB

[Bob K]

Why the Bueller motors?  I need high torque at low RPM, plus they are only 1.9A under load.  It is not speed I am after but enough grunt to shift 29 kg.

Motors & Shafts

It seemed a good idea at the time.,  A novel solution to a difficult problem.  However . . .
After three days drying I carefully lifted the motors from their air drying clay bases -  and the bases crumbled like a packet of digestives that had been used in a warehouse football match.  I am sure we’ve all had biscuits like these.

My build threads include failures as well.   

So, I was hoping to avoid the more complex route, intricately shaped mounting shoes in two inch OD aluminium tube.  It is worth repeating that with the complex hull curves, and four big diameter motors, traditional fixing brackets were out of the question.  The front edge of the motors touch the inside of the hull.

Half circumference shoes cut from two inch alloy tube, notched for the lugs and ground to shape at the edge that touches hull.  Shaped wooden blocks made to support other ends.  Epoxied in position, then padded out with Milliput, leaving a central gap underneath for a Ty-rap to secure.

As you can see below it is all a tight fit, even with the XXL hull size, and occupies the last two feet of the rear of the ship.






I still need to finish moulding around the shaft ends through the hull, fit the “A” frames, shorten the shaft inners to suit, then fit the four 40 mm propellers.

[ballastanksian]

I bet you are glad you bought all that milliput now! I am surprised the air drying clay was so friable as it should have had some ability to hold together, or how on earth are you meant to make anything useful with it? Anyhow, you dealt with more than your fair share of challenges and came up with the goods Bob. The Ties should be enough. Are they removable should you need to do anything to the motors?

Are the knobs on the motors for turning the armatures to a live spot? My dad had an old dumper truck with electric start, but it had a dead spot, so I drilled a hole in the ed of the shaft and a corresponding one in the casing and threaded a bolt into it so that he could turn the armature to a live spot for starting the engine. Its funny how often it stopped at the dead spot!

[Bob K]

Yep Ian.  Just about out of Milliput now so ordered another multi-pack.  No idea what the hex knobs on the rear of the motors are for.  They are seven pole so should not have dead spots.  If motor access is needed I can cut the Ty-Rap and fit another.  Took a trip to B&Q to get these 295 mm long ones.  I had loads of 205 mm but were 5 mm short !  Most with ships this big use car blower motors, which are much wider.

Trimming the "A" frames to exact lengths should be interesting.  I may have to make a rudder shaft from scratch as the standard ones are too short, needing to keep the top above waterline.  All part of the fun.

I dare not start counting costs here.  I intend using the following set of Action Electronics gear for the motors.
Wiring diagram: http://www.action-electronics.co.uk/pdfs/Large%20Battleship%20-%20Eric%20Sims.pdf.
That is two P93 ESC's for the inner shafts, plus a P94 twin 20A ESC's with mixer for the outers.  I am an Action convert, and hate tank steering.  With the outer shafts 160 mm apart it should give reasonable turning leverage in Mode 3, although Ron did describe the original ship as having the "turning circle of a continent".  Hey: My other ships are less than 160 wide with twin shafts only 60 mm apart, they turn on a sixpence.!

[Shipmate60]

Bob,
For fixing motors at odd angles I have tried using "No More Nails" or "Sticks like ****, yes that is the name".
If you want to make the motors easily removable set in 4 hooks so you can use cable ties to secure motors and cover motors with cling film.
But so far I have used some very large motors set directly in it and it holds well.
Just "jack" up the motor then either cover hull or pump in adhesive.


Bob

[Bob K]

Thank you Bob, I may buy some and experiment with it, never having used it before.  Obviously cling film is a good idea so the stuff does not stick to the motor.  This is all completely new ground to me. 

Bob

[Bob K]

All coming along, slowly.  After fitting the motors and shafts inside, next I turned the after hull-half over to finish off the shaft externals and fit the "A" frames.  I always find "A" frames a bit of a fiddle with all the critical angles and curves to take into account.  Again, four shafts adds a new complexity after being used to single and double prop ships. 

Next up, the rudder.  I had to get the largest size of brass-bladed rudder in order to have the servo-arm end of the tube above the waterline.  As usual, trimmed the brass sheet down then built up with two laminates of 1.5 mm styrene each side, expoxied together.  When set, shaping the edges to what I wanted.

Note:  Although the "scale" size of props should have been 30 mm I used 40 mm to give it more oomph.  I also increased the size of the rudder as previously I have found that usually helps achieve a better turning circle.





I may have to wait before ordering the long list of Action Electronics gear from Component Shop, it comes to a fair amount in total.  Well worth it though.   PS: Thanks Dave M, I will revert to Mode 4 for the mixers.

[ballastanksian]

I don't think the props look too large and I agree with insurance over scale or nothing. You are spending lots of time and lots of wedge on her, so you don't want to cut corners on the ability to avoid and fend off and risk sinkable damage as weight weight and momentum will be impressive 

The work is looking good Bob. Regarding your comment on the project coming along slowly, you cannot rush such a project especially because of the huge amount of new technology you are installing. Her size is good reason to pace yourself, as she will become a little more cumbersome to handle as you add more fittings and internal gubbins. I am getting excited now as she may be sailing next year at Wicky :O)

[Bob K]

Thanks.  I am just being extra careful as this giant is taking me beyond my previous experience and techniques.  So much changes when the size doubles.  Ian K's prototype uses 40 mm props so I am confident in those, however it does take the blade tips very close to the keel-plane.  I am keeping a close eye of weight (displacement) as I go.
Collision avoidance at 29 kg and 7 feet is a worry.  Some new transmitters have an altitude setting. Does this mean I could go over other vessels if I had one?

Wicky is the ultimate "target", to make sure HMS Iron Duke has someone to fire back at her.