Topic: 1/32 MTB PT-109 experimental project for this autumn (Read 14204 times)

Backerther · « **on:** October 05, 2024, 10:59:39 am »

Hi all, and Allen A
Are you watching here, Allen ? PT-109 again here!
I have started the autumn project for this year with this pla-model fast boat because I got this in incredibly cheap price.!!
In addition to the above, I like this class of PT boats in its hull shape as well as its proper and sufficient size in storage, transportation and sailing on our lake.

Above all, this is an easy to assemble pla-model kit with potential performance
to run very well on the lake as a fast boat.

Moreover, this kit is not so detailed in many points that is also
convenient and attractive for me to build to get it to run in fast speed, which is quite different from Italeri kits of MTBs.

This kit I got this time was the third one to assemble.
The kit seems so old as to be produced in the first batch around 1980? judging from the tea colored instruction manuals which are like the ancient documents like the original Bible ..???!!!!

Backerther · « **Reply #1 on:** October 07, 2024, 08:08:15 am »

Oh, it's very rare to have found these mal-injection moulded parts nowadays....

Yes, this kit may be truly exceptionally old one judging from these imperfect moulding parts....

So many years seem possibly to have passed since moulded...partly discolored or stained.
Or excess plastics came out of the mould at the branches...

But they are not large problems for assembling,

needless to say. It is just out of curiosity in modern times. !!

Backerther · « **Reply #2 on:** October 09, 2024, 02:26:15 am »

The hull shape is generally well moulded for the old kit.

It's completely Ok for an experimental use as the starting base.

I like this Elco 80 type of hull for a RC fast boat.

I'd expect it to be a good fast runner with new style on our
boating lake as my second PT-109 had performed as I expected it to be.

Backerther · « **Reply #3 on:** October 11, 2024, 06:08:08 am »

Take a look at the following pics. Yes! indeed this hull is necessary and sufficient enough to be a good runner even on the large
lake.

This is no more a toy like size of pla- model hull, isn't it.?

Well then, what shall I do with this large hull next...??

Shall I make a fast boat again in different style to be able to sail on the large lake??

Backerther · « **Reply #4 on:** October 13, 2024, 09:47:07 am »

Now, I have gotten into actual work toward an experimental MTB PT-109(JP).!! Success or not success..???

First of all, I have to secure the water-tight work around the edge of the deck.
The freeboard of this hull is sooo low that the water-tight structure must be indispensable for this fast lake-going boat.!!
Especially on the rough water as seen in pic 4....

I set 5mm square base around the deck cutout to attach the water-tight rubber seal on the base.

Backerther · « **Reply #5 on:** October 15, 2024, 03:39:52 am »

This time I glued the rubber seals on the base to prevent the water ingress.
Slow but steady to proceed to the final success on the lake..??

Backerther · « **Reply #6 on:** October 17, 2024, 03:55:57 am »

I deliberately studied where to cut out of the transom to install the drive system.
And I drew the lines around the transom after intensive study which is very important to install the drive system neatly.

At last, I cut it out roughly as in the pics below. I can't go back to the original shape of the nice hull line any more....

There is no road ahead except proceeding to a successful result of this experimental project.

Backerther · « **Reply #7 on:** October 19, 2024, 02:17:37 am »

And I scraped some convex portions completely which were the very obstacles to set the drive system.
Pics1-2;original shapes
Pics3-4;Scraped completely roughly, but it's quite Ok,!

Now, it's ready to accept the drive system.!

Backerther · « **Reply #8 on:** October 20, 2024, 08:44:32 am »

At last, water jet thrusters have come on in my hands. !!!

At a glance, they look powerful enough to get my PT-109(JP) out onto the lake at an appealing and convincing speed to me as a water jet boat.

I checked roughly the units to know what sort of structure the water jet pump was consisted of....as I do not know much about it.
In this sense, on going project is really a kind of big challenge and an experiment for me to build a water jet boat from a conventional pla-model boat.

Yes, my third PT-109 is going to the water jet style MTB from a conventional screw propeller type MTB.
This third PT-109(JP) will look so old in the form, but will be new in the propulsion system.

Just like a T-type Ford car born in the very beginning of the 20th century with a new hybrid engine in modern times...???

Backerther · « **Reply #9 on:** October 21, 2024, 09:52:57 am »

And I set the Mabuchi motors in the jet thrusters to check if they really work well as the powerful sources for the modernised
PT-109(JP) for so short a time. I repeated it several times having intervals of some minutes between the tests.
Because the motors cannot be water-cooled yet at this stage.
Fundamentally OK as brushed motors....but,..but ...OK...but...I decided to go with these motors for the time being...

Reasonable and final conclusion if its decision is right is postponed to the bathtub test in the near future.

derekwarner · « **Reply #10 on:** October 21, 2024, 10:31:56 am »

Interesting Kiyo........

...why have the cooling water tube inlet side for the Right motor closest to the motor endplate [with the carbon brushes], but the cooling water tube inlet side for the Left motor closest to the motor endpate [with the outputshaft]?

What am I missing?

Derek

Backerther · « **Reply #11 on:** October 21, 2024, 11:36:27 am »

Derek,
Thank you for your comment and a good question on the cooling tube layout.
Unless they are set like that, cooling water coil outlets are not able to face outward each other to drain the water.

This time I bought the cooling water coils which have been available as only one type, unlike clockwise or counter-clock wise
as seen in screw prop blades.
I am intending to reproduce powerful screw prop wakes as in the pic by water jet nozzles, if possible...

Ongoing PT-109(JP) prototype jet boat is so unique for me to build and sail on the lake since I haven't done so far
in my long RC boat/ ship career.

Backerther · « **Reply #12 on:** October 23, 2024, 02:56:59 am »

I made a couple of gaskets for the jet pump thrusters roughly and applied them for the pumps for trial fitting.
It seemed fundamentally OK and will set them as they are as final before installing in the hull.

Backerther · « **Reply #13 on:** October 25, 2024, 03:39:19 am »

Well, it's about the time to install the jet pump units into the hull bottom, isn't it..??

Before that, unnecessary parts of the hull have to be cut them out...!
This is a pla-model boat so that it's so easy to do the above which is one of the reasons I am in favor for the pla-model kits.

Needless to say, I do like the wooden Rc boats,too !!

There is nothing but has demerits or merits in this world, isn't it.!?

I cut the unnecessary parts out roughly and filled the stern tube holes with epoxy.

Backerther · « **Reply #14 on:** October 27, 2024, 01:52:32 am »

I have come up here with installing the pump units actually on the hull bottom for trail fitting.

Everything is going on and on at so so basis.!

The modernised PT-109 is forming at her power plant.!!?

♪～♬～♬～(^^♪

Backerther · « **Reply #15 on:** October 28, 2024, 05:50:45 am »

And I made a new transom as shown below roughly.　♫～♬～♩～♪～(^^♪

swiftdoc · « **Reply #16 on:** October 28, 2024, 08:22:06 am »

That looks nice Kiyo, keep up the good work!

Backerther · « **Reply #17 on:** October 28, 2024, 11:06:22 am »

Hi Arno,
A great thanks for your comment and interest in my PT-109 jet boat project. !!

I imagine it must be so interesting to see the jet boat sail on our local lake at speed with the old-fashioned style of PT-109.
I have thought to discriminate the jet boat from the conventional type of PT-109 by adding (JP) meaning "jet propelled" after the PT-109 like "PT-109(JP)".

swiftdoc · « **Reply #18 on:** October 28, 2024, 12:03:17 pm »

Hi Kiyo,

my Shannon class lifeboat also has two jet drives, my first boat with that propulsion system. In the bathtub it looked promising, I hope it will be the same on the water. At the moment I still need to spray the hull and deck, waiting for appropriate weather…. What make are your jet drives? Mine are Kehrer ones from Germany, bigger than yours as my build is 1/12 th scale.

Regards,

Arno

Backerther · « **Reply #19 on:** October 29, 2024, 01:20:55 am »

First of all, I did not know that your highly detailed Shannon is powered by jet drive system at all due to my poor knowledge
concerning life boat itself. This kind of RC boat is not generally popular here in Japan.
In this sense, I was a bit surprised to know your Shannon is equipped with TWO jet drives....

I have thought for long the boat was driven by conventional screw propellers.....

The life boat is all Greek to me, as I am a Japanese!!

By the way, I know the manufacturer of Kehrer which is so famous and distinguished in this world unlike mine made in China.
Instead, mine is so inexpensive with the quality of so so level...

The water has come through the impeller tube into the hull slightly in early stage and shut it out completely by O rings in the bathtub test for three 3minute tests.

The thrusting force seems fundamentally Ok for me as far as the boat is used for a scale pla- model MTB.!!!
Unless satisfied with the trial on the lake, it's so easy to replace with much powerful motors and lipo battery.
Draining of cooling water is also OK and good for static test of hull.!!!

The motor did not get hot, but a bit warm for 3 minutes test.

This PT-109(JP) could be really and possibly called a very "jet boat" from the pics...????

swiftdoc · « **Reply #20 on:** October 29, 2024, 05:52:38 am »

Thanks for the information, all looks promising to me. I am sure you will make a success out of it

Backerther · « **Reply #21 on:** October 29, 2024, 08:26:59 am »

Thank you so much, Arno.!!

I'm also looking forward to your superb Shannon to have an awesome success on the water in the very near future.!!!

Kiyo

Backerther · « **Reply #22 on:** October 30, 2024, 01:15:47 am »

After checking if the nozzles are neatly and correctly fittted to the main body of jet pumps through the transom via gaskets, I permanently glued and renewed the transom so securely to cope with imaginably and continuously hard vibration of motors to get the boat sail fast on the water.!!!

This boat is intended and expected actually to run fast like/as a jet RC pla-model MTB.!!

Backerther · « **Reply #23 on:** October 31, 2024, 01:59:11 am »

Linkage work around jet pump units and steering servo was "cheerfully" done completely as it was so easy to do.!

Backerther · « **Reply #24 on:** October 31, 2024, 11:11:37 pm »

An easy and happy work is going on and on as seen below.!!

Water cooling tubes and a water proof bag around steering rod were set at this stage..!
I can't wait to see the jet propulsion test in the bathtub. I wonder cooling water should drain well enough..??

I wonder the jet propulsion should come out of the nozzles powerfully or powerlessly..??

This is one of the most important elements leading to a great success in this experiment project used with PT-109 MTB.

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Author Topic: 1/32 MTB PT-109 experimental project for this autumn (Read 14204 times)