1/72 HMAS Rankin (Collins Class)

[Slats]

Be my guest...to add a copy to that thread -glad we all learnt something.

J

[toppack]

Yes, they found out a long time ago that 4 fins of equal size was very stable and easy to control, in air, so looks like it would be in water also.
Example: German V-2 Rocket
It's when they are not equal size, shape and area that you get into trouble.

[Slats]

Rick,
David I think is not saying this at all.

The boat is more manourvable and is more twitchy. Hence less stable and more in need of a sub leveller.

I think David Batagol's boat is simply setup in such a way that by some sheer stroke of luck he finds he does not need it - but the science on this says otherwise.

John

[junglelord]

We must remember that control surfaces of exotic modern planes and modern submarines are interfaced with powerful computers and they do not just fly by the seat of their pants. Is that not true? They have gryos and software and servos. Hence we do too....is that not correct?

Or do modern subs have full manual control with no interface from a correction software and electronic hardware?
I realize that most devices full scale and rc scale can fly by the seat of their pants but sounds like its more difficult then fun sometimes. That is surprising to me as I have no experince yet, except with a Walmart sub, which was extremely stable. I look forward to trying the Seawolf. Mr Merriman says, I have no need for function dive planes on the bow of that boat. So many ideas I had were ALL WRONG....LOL

[Slats]

The answer for Collins is both.

One person drives the whole boat from a highly automated joystick and keyboard layout. A manual mode is also avaliable as a redundancy to the automated systems.

I have taken a tour of Rankin - which is not something that most civillians get a chance to do. Its an amazing technical feat of engineering.

J

[Slats]

On the subject of X fin control, this is how my Collins X fin will work.
Appologies if you have seen this before posted elsewhere...

I use a mechanical mixer designed and built by the grandfather of Australian RC submarines, Jim Russell of Model Submarines Systems Australia.

Sure I could use an electrical mixer for the job, but I like mechanical mixer for two reasons:
1- I can fix it, I understand it, I like it
2- It allows me to use a simply subdriver setup that I can use either in the X fin boat or a standard cruciform boat, where an electrical mixer would not be required.

The second consideration is minor as I understand the radio these days can mix channels too, but the first point is for me the main reason.

Here you see that the mechanical mixer is made up of two concentric cirles (rings) linked to all 4 push rods.

Moving the centre ring controls the helm (left or right). Moving the outer ring controls the pitch (dive /down ; up / surface).

This first photo shows a left hand turn with the inner ring pulled forward, all 4 planes move to command a left turn.



Next the opposite - inner ring back commands all 4 planes to turn right


Finally the outer ring gets pulled forward and this commands all 4 planes to dive / pitch down position. The reverse of course occurs when the outer ring gets pushed back.



J

[Slats]

Well not my design, Jim Russell is a local guru at this sort of stuff, and a great craftsman too.

J

[Slats]

One of my favourite photos given to me by Dr David Batagol...

Dolphins at work and play.

[Slats]

Well the sail master is done and off to Jim Russell at MSSA to make me a super light weight version.

Photos and film etc at 11.(i.e. soon).

Next job will be side sonar array Master - then back to MSSA for 6 moulded versions of them.

many hands make light work - in this case it will help me get the boat running this year.

J

[Slats]

Time to update this thread a bit.

Have been frantically busy at work, but have done quite a bit nonetheless on this.

Here you can see another reason why I am glad that Allan at APS and I are not kit producing this beastie. Its taken a lot a major surgery on my part to get the lower and upper hulls mating true. Not the sort of thing I'd be happy to pass on to any third party as a kit.

The sail development shown here is not the final version. The two versions shown represent both the versions presented by Defence Models and Graphics and APS Models. The DMG one represents the updated design - mooted around 5 years back, and the APS one represents the original design.
The orginal design proved too noisy on the lead boat and this was changed on all boats in the Class.

The DMG one (lighter yellowy colour) whilst featuring the beak at the sail from lower leading edge and featuring the rear modified 70 degree angle piece is wrong on a number of fronts (to be fair as mentioned this is modelled on the improved design and not the in service final product). First the cowling edge of the dive planes are too far back by around 5 mm (noticable), the length of the sail is too long by around 11mm and too short by around 6mm. The sail mounted dive planes supplied also differ in size and shape to the profile of the in service final version. The other key problem with the DMG version is this version tends to be uniform in terms of its width. The real boats when examined head on tend to be pyramidal - fat at the base - thinner at the top.

The more correct version, based on my own research, photos and visit to HMAS Rankin has been built - I'll provide photos soon. This build started with the APS GRP version (which was spot on for the original design), and the beak at the front was added on as was the rear fin extension. In essence this what happened to the real boats. The APS one is the grey GRP one.

The towed sonar array housing aft holds the upper hull down.

[Slats]

BTW - plan on having 4 tubes equipped with the Merriman system - when its ready. The two small holes at the left and right sides of the 4 open tubes will be filled as I goofed on alignment of the two outer tubes. Having the tube doors modelled shut for these will make IMO a nice contrasting feature with the open tubes too.

J

[Subculture]

Can't help thinking the sail has had some input from our side. Looks very similar to sails on the Vanguard and Astute class, especially when you mention they're tapered from base to tip.

It's sort of a half way house between a Astute and 212

[Slats]

Agree Andy

[Slats]

Time to well and truely update this thread.

Herein is an extract from an article I penned on modifications carried out on the sail that was in the Task Force 72 quartely magazine "Course 072".

The next order of business relates to the sail. I purchased one from DMG (Defence Models and Graphics), but the weight was massive, and one key part of running subs is too minimise top weight so as to have little stability problems. You try and therefore keep the weight as low as possible. With the permission of DMG, Jim Russell fashioned for me a light weight version using dimensions of the DMG one out of plastic (quite anachievement) and I thought I was home free and then I reviewed close up photos of the real boat. Foxtrot Uniform Charlie Kilo what an Idiot!……I then recalled that David Batagol built his own sail for two reasons, one weight, and secondly there were some inaccuracies with the scale of the DMG sail.



The DMG sail is modelled around the “in service” or final evolution of the Collins. This version of the sail saw the old sail increased in its length by the installation of a 70 degree sloping rear sail piece and the inclusion of a beak (nose) ahead of the sail. Unfortunately the DMG sail is not quite correct. The beak and rear angled piece are very much spot on, but the sail is too short and too long, the dive planes are the wrong size and shape, and the sail is largely uniform in its width. The real boats sail width is much fatter at its base and narrower at its top. In other words it has a noticeable pyramidal cross section, not a uniform one. Further the positioning of the dive planes and their fairings on the sail of the DMG version is too far back from the sails leading edge. To be fair to Russ (DMG), I understand when this sail was original done, it was done so without the full range of photographic resources now available. Interestingly, I understand that no plans for the final version of the subs have ever been publically released which makes an accurate kit a challenging undertaking.

Conversely the APS models GRP version is very close to spot on for the original “as launched” version. According to crew of HMAS Rankin that I met on a visit, the original sail right through the series of six boats was manufactured to the original plan with the forward beak and angled rear sections simply added on using GRP pieces. Indeed you can see the bolts for these quite noticeably when close up to the boats. This got me thinking – just add these features on to the APS sail as per the real boat. That is exactly what I did and I am very happy with the result.



This project has been a very long road, and I am enjoying the final stages but at times, I must admit, I wanted to trash the bloody thing. There is a market out there for this boat as a kit in 1/72 scale, and I for one would buy one in addition to this beastie.

There is still as afar as I am concerned, conjecture about what constitutes “scale” in the Collins class models built thus far in 1/72 scale and other scales. I do not profess that Rankin will be spot on, but I have gone to great lengths to try and correct obvious differences in the APS and DMG kits to achieve as near as possible a scale result. That said, in the absence of precise plans I do not consider this renovation to be perfect – no doubt there are dimensions and features I have modelled too that are out of scale, and no doubt these will become more apparent as time transpires.

[Slats]

I might point out the material used on the extensions to the polyester GRP sail made use of polyester filler laced with GRP strands. This like with like material is a must. It is known here in Australia as automotive GRP filler.

J