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Author Topic: Higgins PT boat, 1/32  (Read 37346 times)

andrewh

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Re: Higgins PT boat, 1/32
« Reply #25 on: September 26, 2008, 08:03:58 pm »

Andre

Thanks for the information - it is one of the things I had considered, but it will need to run between the planks, and then I will have streaks and globs of epoxy on the outside which will be difficult to sand smooth

welcome, too,  to the Andrew/Andy/Andre thread!

andrew
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amdaylight

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Re: Higgins PT boat, 1/32
« Reply #26 on: September 26, 2008, 11:13:32 pm »

I think your idea of using a low tack masking tape would keep the drips and runs to a minimum.

Andre  :)
Over here in Portland Oregon
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #27 on: September 29, 2008, 01:16:37 pm »

Many thanks for the comments and suggestions;  I got a little build time over the weekend and investigated the unglued-plank issue more fully.
There are only two bays with planks with unglued edges - roughly the motor location area where the botton is concave and the planks twist a lot. 
I have:  determined to use diluted PVA, and add horticultural fleece patches to the inside at the same time.  I'm not going to use tape on the outside because I need the planks to move during the Squoodging process - I will clean up the outside with a wet cloth while the glue is still wet, and check from time to time to make sure that no more has appeared.

BTW - I don't suggest that what I'm doing is the best or only way, just that I have done it in my mind, and expect that I can follow it thru without drama.  There is an aviation saying "Don't let the plane go anywhere your brain hasn't gone 10 seconds earlier"

So progress:  Finished the bow blocks - basically cut out any areas which were not solid and bow-shaped and glued in (PU) balsa block, then cut/planed/sanded to shape


After prelim smoothing


And the transom doubler - 1/4 balsa  - was PU'ed onto the ply transom, and when dry planed/sanded to the complex radius-reducing-to-nothing shape required


I also found the plans (loud cheers) and bravely cut out the formers in the hatch area, but havn't glued the hatch-forming structure in place cos I need the access for the plank repair operation - for which I need the right trousers (breeks with nothing to lose!)


AND I cut out the motor mount plate  - from Satsuma ply.  It is just resting in place at the moment and the motor sits on a blu-tack mounting bracket just to get an idea of the drive train in place - All looks OK to me at the moment



Rudder, FWIW, is home-made from bits I have. 
Blade is 1mm brass from Proops 1pound box - shaped generally as per plan,
Stock is two nesting brass tubes the outer of which fits the commercial tilller arm
Rudder tube is a length or radio aerial tube (chrome-plated brass which is a good fit on the stock)
Whole shebang soft-soldered together

Prop shaft, etc is Graupner nickel -plated with 4mm thread and 35mm racing prop to begin with

I can see this on the water ;D
andrew


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andrewh

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Re: Higgins PT boat, 1/32
« Reply #28 on: September 29, 2008, 01:21:54 pm »

The rudder stock is two tubes cos one is too thin
(To answer the question in advance)
andrew

 
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #29 on: October 01, 2008, 05:03:42 pm »

Rudder assembly - as described before


repair of floating planks by squooging method went very well - no glue penetrated to the outside, but the bottom is now well bonded, and the fleece re-inforcement lays flat(tish)


hatch rails now being added:


Deck planks are stripped from sheet - now I just need to make the remaining hatch crossmembers and I can embark on deck planking.
While the lid is off I have the opportumity to get a good coat of white paint inside to help the seeing and cleaning later in its life. 
What do you do?  Do you bother to coat the insides of boats? 
I know that Glyn doesn't  - I am thinking more about cleanliness than preservation
andrew

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andyn

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Re: Higgins PT boat, 1/32
« Reply #30 on: October 01, 2008, 05:58:54 pm »

You could use halfords grey primer inside, providing that you coat every single little bit of boat....

Looks to be coming along nicely, Llanberis next year???  O0
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #31 on: October 01, 2008, 07:17:07 pm »

Andy,

possibly, possibly

Do you think I could slip in two Zenoahs? ;D

Actually I don't do noise, so the rattiest I would go is three brushlesses
andrew
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John W E

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Re: Higgins PT boat, 1/32
« Reply #32 on: October 01, 2008, 07:38:09 pm »

hi there Andrew

when you have used a soft material such as balsa wood on a hull construction - it is very wise to seal the timber on the inside as well as the outside - although water isn't intentionally wanted on the inside - it sometimes does happen.

An unprotected timber expands rapidly, especially balsa wood.  All the joints (you may find) will open up - even the well glued joints.   So, as has been suggested, a good few coatings of either Sand'n sealer or Halfords spray will do the trick.

Keep up the good work - it is enjoyable to watch someone enjoying building a model so much  O0 .

aye
john
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The long Build

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Re: Higgins PT boat, 1/32
« Reply #33 on: October 01, 2008, 08:06:19 pm »

Hi Andrew
Your build is looking really great.
I to am building this and started 2yrs ago !! , you have nearly passed me  ;D Its interesting to see how someone else does a build and you are posting some good pictures.

At the moment I am just running the boat as it is and it really lifts on the plane when running at full power, its  here that I seem to be having the problem.. I am using an electronize motor with a Viper 15 and 1850 7 cell battery , it lasts for about 15 minutes which seems a bit short to me.
How are you finding the weight as I see you used ply for the formers whereas i have used 1/8th balsa with a double skinned hull and sides, with the 2nd layer being at 45 ish angle, them covered in a very thin layer of tissue paper and dope (Great stuff even outdoors.) and have undercoated with a can of halefords primer .
Inside just coated with some paper and dope again.  No leaks yet 8)

Keep up the momentum..

Larry



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dreadnought72

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Re: Higgins PT boat, 1/32
« Reply #34 on: October 01, 2008, 08:28:59 pm »

Looking good Andy H, no; Andy N, no; Andy G - damn, that's me.

I would coat the insides - but the wood looks so good don't dismiss G4, the resin-varnish pond sealer (sold by garden centres) which is transparent and sets like resin. Because it is.

Laurent, a Belgian modeller sold me on this stuff on year or so back, which has now turned my paper plating into something very like tough plastic.  O0

Andy Someone-or-other
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Capricorn

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Re: Higgins PT boat, 1/32
« Reply #35 on: October 02, 2008, 02:08:19 am »

Andrew, It's looking great, the photo of the great pink glob on the bow nearly made me faint, but not to worry.  I'll have to learn to use foam some day.  I see you used foam for the base too.  I'd agree with the others about sealing the balsa, something that penetrates would be good I think.  Looking forward to test runs, longbuilds too.  Cap
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #36 on: October 02, 2008, 09:21:11 am »

Cap

You are hereby christened Andycap for the purposes of this thread
The foam you are referring to is prolly the very pink stuff that gets everywhere - thats the color of this particular brand of PU glue.  It cures in the presence of water, so before adding the little filler blocks I apply BAS*, just as if i was going to cyano them.  This produces a quick cure (about 10 min) and a plethora of pink froth.  It cuts off in seconds with a sharp blade and carves and sands pretty much like balsa

BAS is biologically available solvent - I lick them

Thanks everyone for your input on painting inside - I'm going your way.
I will give everything a brush coat of my favourite acrlyic primer and then a coat of satin acrlyic - both water-based.  You will all be happy that my balsa is protected and I will be able to see the little widgets that I drop into the hull

larry, thanks for the pics - lovely hull - thats where I'm going ;D
more later
andrew
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #37 on: October 02, 2008, 01:06:25 pm »

Larry,

Been doing a little calculation:  If your batttery is really 1850mah (sometimes much more for small loads) and you are getting 15 mins that implies a current draw of 7.4 amps. 
I know that Electronize do a 3-pole and 5-pole motor in 540 size, and I remember that Pete Miller changed to the 5-pole version after he emptied the bath!  My guess is that you are prolly using the 3-pole version

7.4 amps at say 7 volts is very close to 50watts

This all sounds about right for numbers, but if the duration is too short I'm afraid the only solution is larger batteries (or possibly lower voltage)
The prototype ran, I believe, on a 6 cell buggy pack.  This cuts the peak current a lot, and often seems to give very similar performance for a longer time.



I'd love to see your PT boat in flight from the side - I assume she is planing with quite a lot of the bow well clear of the water as, I believe, the originals did.

The weight is pretty good - I cored out all the formers as much as seemed possible and the balsa is medium grade stuff.

Next job is the hatch, and I have a cunning plan ;D
I'm going to have a plank join at the edges of the hatch and seperate the planks there with some polythene sheet - then I will work inwards to the centre line and finish with a closing kingplank.  I can be sure tha the hatch will come out when I cut the front and back edges.

I'm also expecting motor changes so the entire motor mount will be held in with screws

BTW - I have a bought(!) brushless outrunner which is rated at 110W at modest Kv - Can't for the life of me see why it shouldn't be rather effective - its about 35gm weight vs 190 or so for a S600!
andrew
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The long Build

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Re: Higgins PT boat, 1/32
« Reply #38 on: October 02, 2008, 01:15:19 pm »

Hi Andrew
I am hopefully going to the pond this weekend if aloud , so will try to get some video of it , at the moment it is planing when fully charged as you say with the bow quite out of the water, but am going to experiment with some new props I have.

was a bit disheartened the other day at a local show when I heard a little lad say "Wow daddy look how quickly that BARGE !! is moving" , well at least he agreed it was moving quickly.

Might not bother with the upper structure and rename it a as  stealth torpedo boat. {-)

Larry
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #39 on: October 02, 2008, 01:21:27 pm »

Larry,
Some barge!
I'm sure it is perfect scale for either:
 the delivery passage to the fitting out basin
 or an actual boat on active service after "The Bridge Incident"

Hope the sail goes well, I would be interested in what props you are using or trying
You could send us a pic of your empty bench and claim the low-vis paint scheme works a treat!
andrew
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #40 on: October 04, 2008, 11:53:20 am »

Now LOOK what the massed Andys have made me do!

This is after the primer - looks a bit scraggy
BTW - there is a (deliberate) error here - I have run the hatch from Bulkhead to bulkhead, but the plan stops it about an inch short of each end - which strikes me as strange but possibly functional thing to do



after satin topcoat

and close-up


Deck planking today - I will insert large bits of foam before the deck goes on, and probably the motor mount base plate - since it runs most of the way acrosss the bottom, and may not be east once the deck is on

andrew

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The long Build

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Re: Higgins PT boat, 1/32
« Reply #41 on: October 05, 2008, 05:57:04 pm »

Hi Andrew how is your Higgins getting along ?

Took mine it out for a run , using a bog basic carbon 40mm prop, as the video shows it is lifting nicely at the bow however I am not sure if this should be higher ?.  Unfortunately the pond was full of leaves &  twigs which kept snagging the prop , the engine even after this short 40 second run became quite hot to the point that it actually was seizing until it cooled down, so was thinking of adding a couple of Graupner large water cooling inlets and a carbon Hydropropeller 42mm next time.   

http://www.youtube.com/watch?v=ncKI2CQLUsU

Look forward to seeing yours in the water.

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andrewh

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Re: Higgins PT boat, 1/32
« Reply #42 on: October 06, 2008, 01:08:31 pm »

Larry,

Thanks for the video - havn't been able to access it yet - Utube wants me to log in and I don't.

Fron a distance, and in large ignorance, it seems to me that the prop may be larger than the motor and its cooling likes.  Adding cooling coils will certainly improve matters.

But I can be ABSOLUTELY certain that increasing the prop will accelerate the overheating, but the ride might be exilarating while it goes.
I am not at all a boatie, but my habit while flying would be to reduce the prop size till performance drops off then increase gently till you can live with the duration - this will give the coolest motor for a given speed, and will be quite sure that the motor is spinning as fast as possible - thus giving the highest eficiency.

I did have a re-look at the original article and found that Pete M finished up with 7 cells and an Electronize 3-pole motor, but not the hottest one, so probably the 7 amps I estimated for your boat was much the same as his.   If that is what you are using the motor should be reasonably happy and cool (altho stalling on weed or sticks could lead to a huge overheat - if the ESC permitted the current to flow)

At my rate of build I would expect to overtake you perhaps tomorrow ;D ;D

starting planking- orange is polthene bag to allow the hatch to release




andrew

 

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The long Build

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Re: Higgins PT boat, 1/32
« Reply #43 on: October 06, 2008, 01:21:52 pm »

Not sure you have enough pins there. {-)

Ps Ducks were not impressed either when i went a bit to  close by accident , glad there was nothing on the deck as he used it as the takeoff platform..
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #44 on: October 06, 2008, 01:52:10 pm »

You ain't seen nothing yet - That pic was taken about 2am and shortly theafter I borrowed a load more pins and completed the planking


The gap in the centre of the hatch was not really planned - I just could not get my hands into the forest of pins ;D
It came in very useful in removing the hatch for the first time - I could pull upwards with a wire hook poked in thru the gap.  It all went well and the hatch separated sweetly.

The next stages (sanding, doping) I aim to illustrate using the new mayhem facility which is a bit like Photobucket, but involves delivering dust and smell to your computer (Dustbucket and Dopebucket0  If you do not have an account with Dopebucket you can read the post while spraying yourself with the wife's hairspray.

Why are you looking at me like THAT


The fretful porpentine!
andrew
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dreadnought72

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Re: Higgins PT boat, 1/32
« Reply #45 on: October 06, 2008, 02:10:03 pm »

I always think it's a shame to cover things like that up! However, in the interests of safety and accuracy, you've made the right decision: looking forward to more.

Andy #1963
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andyn

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Re: Higgins PT boat, 1/32
« Reply #46 on: October 06, 2008, 05:48:53 pm »

How are you protecting the other side of the deck planking?

Andy #1964
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #47 on: October 07, 2008, 11:39:06 am »

Andy - any and all Andys!

Other side of the planking? - forgive me - I must be slow today.  Not sure what you mean. 

Larry - video works.  Nice  high-speed barge!  Have you also got an IC engine in there?  The noise level - imho suggests something catching, interfering or otherwise not aligned so as to be completely smooth.

Progress so far - deck planking lghtly planed and rough sanded - (the hatch in this pic is slightly raised - intentionally)
 
And  the hatch comes off!


andrew




All the hull needs finish sanding, 3 coats of dope then heavyweight tissue applied wet with thinners
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andrewh

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Re: Higgins PT boat, 1/32
« Reply #48 on: October 07, 2008, 11:43:26 am »

Non-sequitur!

Before decking, I cut some foam to filll  the bow compartment - polyethylene foam FWIW, same as I used for the stand - we get huge sheets with some purchased components

the foam is just visible filling the compartment behind the forepeak
andrew#00000001
 
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amdaylight

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Re: Higgins PT boat, 1/32
« Reply #49 on: October 07, 2008, 04:55:07 pm »

What he was talking about is the under side of the decking, the inside of the hull. I usually paint the under side of my deck planks before gluing them down.

Andre, Andy 1959
over yonder in Portland Oregon

PS I take the Andy from my last name Anderson {-) O0 {-)
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