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[swiftdoc]

Ready for the maiden voyage   I will keep fingers crossed that all will go well, Kiyo!

[Backerther]

Arno, a great thanks for your encouragement for me.!!!!
Well then, shall I try to boost it ahead with this jetted MTB on the lake in the near future if it's fine weather.!!
Like our latest H3 rocket succeeded in launching the other day totalling to 3 continuous success.

[Backerther]

I installed a foldable wave deflector over the jet nozzles for an easy service of nozzles as well as deflection of the wave and a
scale like good appearance.   As this is an experimental jet MTB that I have challenged to build and sail her on the lake.

[Backerther]

And I weathered the boat briefly and roughly like these. Coming to a final configuration gradually..!!

[Backerther]

She is no more USN PT-109 but IJN PT-109JP by the national flag and the navy ensign as well as twin jet thrusters.

[Backerther]

At last, I happened to find a nice weather yesterday for testing my PT-109JP.
At first, I checked the balance and confirmed it OK for an initial trial run after checking radio wave range test at the distance
of 82ft.
And I got the boat afloat and set the balance as seen below.
A model ship does look fine when floated on the realistic water under the nature once completed, not in the bathtub, doesn't it.??

Pic No1: The sunlight was reflected tenderly along the starboard via water surface in the deep autumn of Japan.....
The water was fairly clear and clean typical of mid-autumn of Japan and suitable for RC boating as well.!!!!

[swiftdoc]

Great pictures, Kiyo! Over here we have rain and snow at the moment….
How did she perform on the water? Was the thrust of the jet drives ok?

[Backerther]

Good morning, Arno and good cold evening here in Tokyo with a slight rain fall.
Thank you for your comment and interest in the sailing performance.!!
At the same time, I am awfully sorry if I have you provoked due to no reference to the important sailing performance.
I did not dare to refer to the point as I had thought it would be done in the next post....
But you showed an interest in the above comment, I will post so tiny pieces of pics below prior to the main body of sailing pics
to be posted tomorrow.   Please excuse me for my provoking thought.


1, Safely started !!
2, Safely returned !!

[swiftdoc]

Many thanks for sharing the photos, Kiyo, it all looks promising! I did not want to force you, it is only that I am very interested as my build has jet drives as well which so far have not performed on our club pond….


At the moment I am installing the trim tabs and reversing buckets. When that has been done, I will post some photos on the forum in Kim‘s thread. I am still waiting for the Super X glue from Tokyo, which is now at the customs office in Amsterdam….

[derekwarner]

Hullo Kiyo........I have followed this thread from day 1, & progressively wondered about the Jet Drive water exit axis...[relatively to the waterline]

I have Zero knowledge of these types of propolution apart from viewing a few U-tube shows

This function I don't understand    is semi-submersed jet water output, as compared to alternate submerged jet water output

The attached image is the RLNI lifeboat build here, but with submerged jet water outputs........

I keep on questioning the component of the jet water output    above water....could it be wasted energy?

Derek

[Backerther]

I'd like to respond to your kind comments in order of posting.

Arno,
I'm awfully sorry to have kept you waiting so long on the report of my first trial run on the lake.
I declare proudly hereby that the world's first PT-109 1/32 propelled by the water jet thrusters has been born successfully
at any rate.!!!!!   This is merely an experimental prototype of MTB built and modified from just a pla-model kit. My PT-109 JP does not have such nice reverse buckets as your refined ones..  
Needless to say, additional improvement and adjustment are surely required to get her to sail for more refined running.
And this trial is just the starting point for a better jet-driven MTB PT-109 as to need more months to go.!!

Arno, the video will be, of course, exhibited here tomorrow.   A motion picture tells truly, honestly and vividly all how it performed.
      Seeing is believing.!!!

[Backerther]

Hi Derek,
Thank you for a nice comment this time as well.
All what you mentioned was truly to the point and a good question, since even I have been wondering how I should set the
nozzles position against water line throughout this experimental build.
I do not have any experience nor instruction manuals to which I am able to refer like the holy bible in life except not so many
information in the internet.
 To tell the truth, I have been questioning by myself how I should set the angle of thrust line against the water line and the he ight of the nozzles along the transom.
The former one was sooo difficut to cope with by myself and decided to set it along the bottom of hull.
The latter is what you mentioned and I have seen a certain you-tube(a Japanese posted) in which the Japanese denied to set
the nozzles fully in the water as ineffective than fully over the water through his experiment in the you-tube.....


Therefore, I simply decided to set the nozzles at semi-submerged line as seen in my pics based on partly because of the Japanese experience.


Anyhow, now I am planning to try various ideas to search for what will be the best for a better sailing performance with these
jet drive units and brushless motors, which is one of this experimental projects.

[derekwarner]

Hullo Kyio.....just a few points..


1] I fully accept that the MTP- 109 vessel is not intended to be a speed boat of a totally different class and configuration
2] I believe the original MTP Class of vessel when @ speed displayed a stern down in the water with a sizable powered wake fantail trailing the speeding vessel, and all the time whilst raising the bow up & so achieve the plane on the water

I think you have achieved all of these points in this, your latest build

There is another point often commented......." a fast designed boat going slow does not show any real interest "....whereas an alternate designed vessel going slowly but whilst displaying a great volume of spray from the stern will always of interest"  

OK?

Derek

[Backerther]

Hi Derek,
Yes, indeed.!!  I quite agree to what you stated in the last paragraph.
So far as this is originally a RC scale MTB PT-109 1/32 which MTB is not a racer but a fast sailing(sailable?)craft, she has to run
moderately fast, not like a turbine-jet runner.
My initial aim to build this water-jet boat is partly because I was bored with a conventional type of screw propeller for this PT-109
as I had been enjoying a nice and sufficient speed by my second PT-109 already, which video was frequently shown here.
This boat could afford to gain more top speed by some ideas I have in mind and I intend to apply them seriously for her within
the year, if possible.
I like such a RC model just as T-type Ford 1914 to be able to run at speed over 60MPH.!!

Pics; Trailing wake is quite different each other naturally.

[derekwarner]

Yes, the MTB certainly shows the fantail wake over the conventional propeller drive.........looks fast at any speed   


I equate a similar observance or comparison......a conventional propeller driven Ferry vessel at 3 MPH, to a Ferry of similar size, but paddle wheel driven ....at the same speed 3MPH thrashing the water about    as she moves bye


Derek

[Backerther]

Derek,

I found an interesting you-tube of a missile patrol boat driven by tri-jet drives of Japan maritime self -defence force (so -called Japan Navy nowadays). As far as I can observe it, her nozzles of three jet drives seem semi-submerged....in this case...???


Bing 動画

[JimG]

A couple of observations about the nozzle position. I have the Graupner Pilot boat with 2 waterjets and the nozzles are positioned above the chine height at the stern so would be semi-submerges when stationary. This position works well at all speeds.While the Shannon has the nozzles below the waterline when stationary it does have a planing hull which would be expected to lift at higher speeds bringing the nozzles above the water level, I would expect the transom to be above the water flow so the nozzles will be fully exposed, the trim tabs should help lift the stern clear.  Having them submerged at low speeds may add a bit of extra thrust when the jet flow is pushing against the water more like a propeller but the main thrust from a jet is by throwing a mass of water behind the boat and using Newtons laws to propel it forward, no need for the output to be submerged.
Jim

[swiftdoc]

I cannot tell how the thrust of the Shannon boat works. At low speed the nozzles definitely are submerged, but at high speed they might well be semi submerged. I have attached some photos of the Open Day at the Dungeness lifeboat station in 2017, happy days….

[swiftdoc]

at high speed…

[Backerther]

JimG,
Thank you for always nice comments.
Your information mentioned above from your experience could be soooo useful for me this time too as I am quite a beginner
in this water-jet drive system. And I could deepen so informative and scientific knowledge concerning jet drive characteristics.
What you mentioned did meet what a certain Japanese in a you-tube had confirmed that nozzle fully in the water did not contribute less to thrust the boat ahead than fully over the water. As you mentioned, I just once imagined that sizeable and fast volume of jet flow over the water might be something like a key to push a boat ahead fast like a rocket......But I was not completely confident about that in those days.
 Therefore, I set the nozzles of my MTB at semi-submerged conditions provisionally as seen in a missile patrol boat in a you-tube posted above. See the pic stationary on the water and the other sailing fast when the nozzles were over/on the water
subsequently....??


Anyhow, thank you for sharing your precious information on the jet drive mechanism with us.

[Backerther]

Arno,
Thank you for some nice shots of real Shannon boat sailing so powerfully with sizable splash.!!
I suppose your Shannon will do the same actually on the water as the real one with its museum quality appearance.
When are you supposed to make a trial run after applying Super-X Black.?
You had better keep the model left over 24h minimum for a secure cure.


I am waiting for your Shannon to make a wonderful trial run in the very near future in Kim's thread.?

[Backerther]

I'm so glad and happy to be able to post this video on here of the first trial run of this boat started to build three months ago.
Whether or not the content would be satisfactory is entirely dependent upon you yourself, but it's a bit significant for me
to be able to post the video of the experimental project to build a jet-driven MTB from a Lindberg Pla-model kit regardless of the content.    This is merely a prototype of a better jet-driven MTB to be expected to perform much much better on the water. 
Please watch it in full screen of PC for better and vivid appreciation.!!
The video will surely tell all that I want to comment more eloquently than my poor description in three-minute watching.


Bing 動画

[swiftdoc]

I have watched the video and enjoyed it, Kiyo, although I was not able to understand the comments of your wife as I do not speak Japanese   It all looks ok for me concerning thrust and maneuverability.


Over here we have ice and snow at the moment and I cannot do the paint job of the deck. So my maiden voyage will not be possible before next spring.

[Backerther]

Thank you for a warm comment, Arno.!!   I'm so glad to read it.!!
My wife said," May this boat succeed in the first trial run!!" in the former shout and "3 minutes have passed" in the
latter.   She played a role of both a camera-woman and a time keeper for this test sailing as I forgot to carry a kitchen timer around my neck.

I've often heard from a friend of mine working for a trading company that Germany is generally cold across the country and it's understandable if I may see an atlas of Europe. That's why Christmas in snow of Germany is so famous and my wife has
made me nervous to appeal her strong wish to see a Christmas scenes at night in snow of the country.
The notorious is the very low Yen value that has been a worst reason to disturb the trip to overseas travels among the Japanese. 

[swiftdoc]

Your wife does a very good job as camera-woman


 I have attached a photo of how it looks like over here today. Not much snow, but enough to get an impression of winter.


The weak Yen is convenient for us though: my daughter is planning a visit to Japan for next year (again).