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[Backerther]

Arno,
A great thanks for the photo you sent me and I have shared it with my wife right away.
She said it looked something fantastical since it was quite different from our normal circumstances at all, while it may be
nothing but normal and daily scenes for you, though....
Anyhow the scenes covered with white snow may generate something fantastical or mysterious partly because of strange  environments of your country against Japan...

Thank you again for the photo.!!
PS;
It is too long for you and me to wait and see Shannon sail on the water until next spring while she is nearly about to launch at the moment.

[Backerther]

A rescue operation done in the second trial run.!!!!!!!!!!!
Everything did not always go well in this world, didn't it.!?...........Our latest H3 rocket failed in the first launch followed by
3 successful continuous launches thereafter....
A flock of waterfowl was watching me save the boat anxiously, interestingly and curiously as seen in Pic1...
I wonder they would understand my feeling of the time or despising me for the failure..

My PT-109JP was sailing very well in the first 2 minutes in the second trial run and suddenly stopped about 40 m(131ft) off the
shore just after Port steering.!!!!!!!
Right motor was judged to have had a trouble after examining the cause......Left one quite well......

[swiftdoc]

Oh Kiyo, what a pity! I hope you can find the reason for the failure soon. Did you take the inflatable boat with you in your car? At least you had the possibility to rescue the model safe and sound…


P.S.: My Super X glue has arrived yesterday, no customs fees and no import taxes   I will give it a try today, then wait until it has fully cured, followed by a longer bath tub test….

[Backerther]

I found the cause of motor trouble unlucky due to the cheap motor which are often unstable in its quality...
Or insufficient cooling of motor on this right side since I felt too hot right after first trial run while cool on the left motor.!
I will be able to re-start the trial/improvement run from this December after having a replacement motor made in China again.

I normally make it a practise to carry an inflatable rubber boat whenever I sail a brand-new boat at its early stage or I am
not confident of a boat from its past experience.....
I have ever lost a RTR tugboat here several years before, that was drifting away for 2km(1.25 miles) after sudden stop...
I chased it from the shore in the mid-summer as far as chained buoies like a rope (I do not how to express correctly ) where it was forced to stop and seemed to sink as I could not see it any more.....    Only one victim here...

Quality of the Super-X is really excellent as this is Japanese brand of Cemedine brand.!!  Very famous and traditional brand of adhesive and its relating products here in Japan.

I will be so happy if I could enjoy a nice Christmas cruise before Christmas with a Santa Claus as in the pic..!!

[Backerther]

Arno,
I once watched this interesting, unique and useful you-tube for my PT-109 JP setting concerning the position of nozzle along the
transom.

He concluded from his experiment that nozzle set over the water came to be much much effective to thrust the boat than fully in the water.
This conclusion seems to match what JimG previously mentioned.!!!


Bing 動画

[swiftdoc]

Kiyo, I think this is no contradiction. When the Shannon boat comes to planing, the nozzles might well be above the waterline and so do yours. The Shannon ones are submerged only at low speed.


The guy in the video does not get to planing his state-of-the-art hull🤣

[Backerther]

Arno,
This is just a question on your Shannon.
Does she have trim tabs already.?
Can I see them if you don't mind showing here..?  If possible, I also intend to install provisionally in my experimental PT-109JP
to know how effective tabs of my style will be in my boat.

[swiftdoc]

Hi Kiyo,


I have attached some photos of my trim tabs. I have installed them yesterday   They are workable as I have soldered a steel wire into the cylinder which is attached to the tabs. The tabs are made of brass sheets, cut to size and then soft-soldered together. I have used brass tubes for the cylinders.


You will also notice the fixing of the bellows, having used Super X glue. I will do another bath test when this has fully cured and then attach the deck if the test will be successful (i.e. the hull will be dry inside after the test). The trim tabs can be adjusted using the slider controls of my Futaba transmitter. It worked fine during the dry test yesterday.

[Backerther]

Wow!! Arno, amazing!!!!  Your Shannon with an extremely refined construction of jet drive with reverse buckets.!!
And it's so large a boat enough to install also nice and adjustable trimtabs by your radio stick work that is really like a real system including the shapes.!!  
Moreover, these jet-drives look to adopt a pair of fully advanced thrust vectoring nozzles, don't they??  This is also amazing.!
 So well crafted and constructed, Arno.!!!!!

I could generally understand  how your trimtabs were made.
Thanks ,Arno!

[Backerther]

While waiting for new motors of replacement to arrive at, I painted 6 crews and got them be at quarters as seen below.
The rest two are still taking a rest for future service.
I think they will surely experience comfortable speed by jet power actually aboard the boat.   
How I envy them.!!!
But it will be soo cold in coming December.... Me too!!!!

[Backerther]

I'm currently so happy to have myself indulged in building so unique an MTB PT-109 jet propelled based upon my own ideas and design using Lindberg pla-model kit for an autumn project.
Anyhow, a jet propelled boat is itself very new to me and therefore I have little knowledge about its behavior how it performs
together with the boat on the water. In such a background, I intend to try some experimental tests furthermore to make my PT-109Jp much better until I will abandon my improvement efforts.

I added a kind of trimtabs to get my-desired balance in sailing at speed. These tabs were this time just set as the starting point.
This boat is merely experimental so that I wish to try some tests having the interest and collecting knowledge.

[swiftdoc]

Though I am a novice to jet drive propulsion just as you, Kiyo, I am quite sure that it will bring an improvement. What you might consider as well are those fins underneath the hull which the Shannon boat has. I think they improve the running straight ability.


I hope the next test will end without the need of using your inflatable boat

[Backerther]

Arno,
The inflatable boat is perfectly prepared to carry with me currently for emergency....
As I had a very terrible experience to take a looog time to inflate it just after the sudden stop of PT-109 on the water during which the 109 had been drifting away from the initial place of stop on the water already.....
I haven't used the inflatable boat for many years up to the day since last I had used....I forgot how to inflate it correctly under
emergent condition....    Normally ten minutes to inflate it but might be close to 20 minutes in my feeling..
 I am expecting how she may behave in the next trial run with the trimtabs and other countermeasures taken into the boat based on the first trial run.


This time I have two crews set to let them check how cooling water is drained during sailing since I am completely unable to see it due to the wave beside the freeboard as seen in the pic.

[Backerther]

A new replacement motor arrived and I set it in place after setting a clamp to tighten the cooling coil for better contact
with the motor to get a better heat exchange.
The new motor worked very well in the bathtub test for two times of 5-minute run and ready for next trial run on the water.

The test is supposed to aim at confirming if the trouble of sudden stop on the water in the last test should never happen again and trimtabs also might produce something effective for a better sailing behavior.
Needless to say, speed performance may well be improved by some measures I had applied.

According to the latest weather forecast, it will be fine fundamentally throughout next week.  
Everything is up to my boat itself whether or not it will be successful...

I will be very happy if I could post nice shots of sailing here of the run.....
I wonder if she is sufficiently tolerable against fast continuous speed run by powerful brushless motors judging from the last experience...?   Many screws loosened?...ESC burned out?...motors also blown off?...motor mount cracked?..
Or Should I treat her like a tame cat rather than a wildcat on the water..

[Backerther]

Hi dear,  just pics for today.!
It was really nice day here in Tokyo for sunbathing in the sun given by a slightly hot temperature of 18 degrees C(64.4 degrees F)
, no cloud in the sky and no wind over the lake as seen in the pics.
I manned my PT109JP and set it to take the sun for a while from stem to stern as in the pics.
Take a look at our naval ensign of the rising sun which really matches the sunny day, doesn't it. ?   Wow!

[swiftdoc]

Wow Kiyo, lovely photos! And yes, the ensign matches perfectly   It all looks very promising for the next test run.

[Backerther]

Arno,
Thank you always for a friendly comment.
A jet-driven boat could be more promising as one of the drive systems for RC vessels, at least for me.!!


 What a happy day, a happy place, a happy boating, a happy hobby, a wonderful world ♩～♪～ under the blue sky and warm, calm weather.!!

[Backerther]

Well, it's a highlight of the second trial run to report for today.
Yes, sailing scenes of the 109JP in standstill images....   However they are rather impressive, dynamic and appealing
often than motion pics like video.
Here we go!
Pic No4 is at full throttle scene.

Just some remarks;
a) My own style of trimtabs set this time were functioned to some extent as to reduce ugly and unrealistic rooster tail like wake.!
    Due to the tabs, tail wake could be kept lower and sharper as she got faster than in previous trial run.
On the contrary, Stb motor stopped again at terminal stage of sailing at speed while Port motor was quite OK enough to drive her home powerfully at shore.
b) The tabs also contributed to refrain from excessive bow-up tendency at high speed.
c) The waves beside the both sides were comparatively well formed clearly and sharply by added bilge keels as in my PT-109
screw propeller boat previously completed.

Fortunately or unfortunately, inflatable boat could not have any chance to go afloat on the water though fully swelled put beside me... 

[swiftdoc]

Kiyo, I hope you can find out soon the cause for the motor failures! Apart from that the photos show that she sails nicely on the water. What revs does your setup achieve at full throttle? My Kehrer jets should not have more than 20,000 revs, which I do achieve using 1,600 KV motors running at 3S lipo batteries.


I had another setback as well as I still have some water ingress. I found out that it must be where the jet drives protrude the transom. I had used Gorilla glue for the joints as this expands into the material. I now have ordered some more Super X from Japan and will apply that also in those places. Did you do that as well with your drives? The Super X does a fine job so far around the bellows and all the other protruding places, for example the fixings of the trim tabs and the reversing buckets.


I am sure both of us will be getting there slowly….

[Backerther]

Arno,
I have understood your embarrassment on setting the jet drive system quite well since I already had nearly the same experience
and took much trial and error for solving such troubles, though I did not refer to these points so far in detail.

1) As for the motor revolution; I have not measured it. I simply am using a 2S lipo 5000mAh battery with 4000KV brushless
     motor. Unlike your large? motor, mine is so small that inevitably KV value seems a bit higher...although this motor is also
    applicable for 3S lipo by its specification, if necessary.  BUT I haven't felt it necessary to use 3s lipo at all. See the pics posted        above. It is 50000RPM max with 3S lipo by its specification, namely 3S x 4000KV=about 50000RPM...
   Anyhow, powerful enough with 2S lipo...see pic below.
2)As for water ingress; I was also terribly embarrassed by this ingress frequently in early stage of bathtub tests made many  times.  
In order to prevent the water from coming into the hull, I used super-X finally all around the base of pump units and all the protruding places beyond the transom sufficiently after all by which no drops could be found in both bathtub and on the-water-test.
I addition, a few drops of ingress was confirmed coming through the stb impeller shaft against which super-X and a good amount of grease as well as double O-ring did a very good job to stop the water ingress. !!!    
Double Oring can be seen in Pic4/5 clearly.

In the early stage of installing the pump jet units, I thought the gaskets would work sufficiently to stop the water ingress in vain.....insufficient and Super-X solved the embarrassment completely..!!

[swiftdoc]

Thanks for the photos and information, Kiyo. I will do the same around the jet pipes and that will hopefully solve the problem. I now am waiting for delivery of the Super X sealant.


The Kehrer jets are allowed only about 20,000 rpm because of the bearings. Your setup might be too much revs concerning the shafts and bearings?! I have no idea why your one motor has this problem and hope you can solve that soon.

[Backerther]

Arno,
I'm sorry to have you misunderstood the set-up of the radio gears.
I just mentioned the capability/specification of the motor referring to 3S lipo and actual set up is by 2S lipo that is quite Ok
as in the pic No1 in the above post. Theoretically my motor could produce around 33000RPM at no load, but actual RPM will
possibly be far less than or around 20000RPM at best due to many factors...
Moreover, I could only believe in partial parts of the specifications of the motor made in China from my several bitter experiences in the past.   I suppose the motor failure will be solved shortly in the month in the third trial.
I am intending to improve a bit sailing attitude at speed for more scale realism.  

[swiftdoc]

OK, that all sounds reasonable to me, Kiyo

[Backerther]

And this is the video of the second trial run to have come successfully to end with a partial failure....
I already think myself to have found the cause of the trouble of the motor, though direct cause may have nothing to do with
the motor which I'm not sure...
The third test will exhibit if my supposition should hit the case shortly in the month.


https://youtu.be/IFC2I6fBDRA

[derekwarner]

Kiyo.......she accelerates in a most scale-like motion ......[she is not a speed boat]


The sound in the video opens up some questions in-relation to a drive alignment?, or shaft-to-bearing tolerance within the actual impeller shaft within the pump itself


In the timeline.......26 seconds >>>>>.40 seconds as harmonic resonance, then ...... to 50 seconds an alternate resonance ...there are other resonance sounds, however these first two [edit] for a start

Do you hear the same?


Derek