Models By Design T-class

[Ironhorse]

Hi Folks: Here I send you some pics of my new ride.Yep the big T-class from Model By Design UK.Just prior starting the aging and weathering.
Hope you like it.:wink:
It uses a3,5 DE subdriver

[Kazzer]

Wow! That looks really good. Post a LOT more pictures please. Lets see the rudder and rear dive planes mechanism.

I hope you have a D&E Sub-driver 3.5/2 (with 2 motors)

Is it in the water yet?

[VanguardUK]

very nice, what happened to the other t build on here?

[Ironhorse]

T-Class Tally Ho

Hi:
First of all thank you for your interest.
Today I am sending some pics about the progress made in the model.
You can see the 3,5 Subdriver already fitted and some preliminary work to make the capacity of the ballast tank adequate to the needs of this ship.Also you can see the bulkheads for the subdriver and the lead shot added to the keel and fixed in place with drops of Ca. The foam added for the moment has given almost the right surface trim together with the foam fixed under the deck.It shows very good stabilty in the rolling plane thanks to the long arm force.well... next is testing the submerged trim.
Also I send some photos of the conning tower already weathered.
I promise to send you good pics of the rear rudder and planes linkage although I can tell youthere is nothing special here only some carving with the moto-tool and careful fitting.

[Ironhorse]

The T goes to swimm

Hello everybody
The trimming of this large boat was awaited with some trepidation.
Once in the water it results to be not so complex as expected.The real breakthrough is to reduce the ballast tank size (in my case using foam cut in discs).Initially it showed some list that was easily corrected taking some foam from the side (Surface trim) The waterline as you can see is quite correct.
The submerged trim initially showed the bow to be out of the water.This was corrected taking some foam from the bow and adding 20 grams of lead up front.Also I added some more foam under the deck at the stern.
Anyway no big deal whatsoever.....Now I am going to hook the control surfaces and installing the Snort system and the wonderfull ADF ordered recently.

[Ironhorse]

Rudder and stern planes linked

Hi: As I told you yesterday I have installed the Snort system and the tubing which go to the ballast tank and to the sail.I decided to use some fuel line of the commonly used in gasoline engines in RC airplanes.(Not silicone)The Clippard line is too tough to take curves easilyso I decided to use it only in the straight portions.
After some fiddling with the pump I decided to locate it transversally behind the servos and held in place to the floor with a nylon tie.It worked very well first time.Same to say about the ADF although there should be some conflicting issue about the Futaba PCM radio regarding the ADF failsafe.It simply does not work.However the failsafe of the radio functions perfectly....The pitch control just perfect.
I do find the 1/16 brass rod used to connect the SD to the control surfaces somewhat flimsy but if we provide some intermediate station the binding is reduced to manageable proportions.
The stern planes are linked trough an elevator horn also coming from RC planes.You need to carve the stern post deep enough to install it .The horizontal 1/8 in solid brass rod goes trough the end and uses some brass tube as bearing surfaces .The whole thing is fixed with the set screw provided you will need to drill a small hole to access with the allen key.
The rudder post is solid brass running on brass tube bearings nothing fancy here.
All the control surfaces were made using PVC sheet which is carved easily with hand tools and take the Ca glues very very well.
Next will be the front planes linkage.
Hasta Luego

[Ironhorse]

TallyHo at the lake

:wink:Hi: First test at the lake.Some bugs to be ironed out but otherwise quite satisfactory.(Some small leak traced at the fixing screws of the valve/servo bulkhead and subsequent fogging).Some porpoising (even with the ADF...needs better adjusting)

[VanguardUK]

Why did I ever sell mine??? Moron.

Nice boat, I will have to build another one after the Type21 I've just aqquired

[Ironhorse]

Perhaps the most unique shaped Sub Of WW II

Hi Vanguard: Yes By all means build another one.Really is very rewarding watching her going underwater.....Its unique shape make them unmistakable.
regards

[He Who Shall Not Be Named]

Hi: As I told you yesterday I have installed the Snort system and the tubing which go to the ballast tank and to the sail.I decided to use some fuel line of the commonly used in gasoline engines in RC airplanes.(Not silicone)The Clippard line is too tough to take curves easilyso I decided to use it only in the straight portions.
After some fiddling with the pump I decided to locate it transversally behind the servos and held in place to the floor with a nylon tie.It worked very well first time.Same to say about the ADF although there should be some conflicting issue about the Futaba PCM radio regarding the ADF failsafe.It simply does not work.However the failsafe of the radio functions perfectly....The pitch control just perfect.
I do find the 1/16 brass rod used to connect the SD to the control surfaces somewhat flimsy but if we provide some intermediate station the binding is reduced to manageable proportions.
The stern planes are linked trough an elevator horn also coming from RC planes.You need to carve the stern post deep enough to install it .The horizontal 1/8 in solid brass rod goes trough the end and uses some brass tube as bearing surfaces .The whole thing is fixed with the set screw provided you will need to drill a small hole to access with the allen key.
The rudder post is solid brass running on brass tube bearings nothing fancy here.
All the control surfaces were made using PVC sheet which is carved easily with hand tools and take the Ca glues very very well.
Next will be the front planes linkage.
Hasta Luego

A well engineered installation. Tell me, what problems did you encounter with the 3.5 mod 2 SubDriver -- the idiot designer wants to know.

Is the power of the motors adequate for this boat? What is the diameter and pitch of the propellers? And what is the capacity of the battery and how long a run do you get on a charge?

Good looking assembly on the kit too. Nice lines.

David,

[Ironhorse]

3,5 Subdriver.

Hello Mr. Merriman:
First and foremost I would like to give you thanks for designin such a clever and ingenuous piece of machinery and second for showing your interest in my model.
No problems with the design of the SD and its functioning but (there is always a but..)You would simply discard those poliurethane mouldings showing excessive bubbles.These surely don´t compromise the integrity but degrade the look of the finished product.
The ballast tank should be adjusted in its capacity to make it enough for the displacement of the ship.Reducing the flooded space with Styrofoam discs is an option.(nothing new here)
The SD is placed (and its ballast tank) is amidships a bit forward of the CG.(about an inch) This position has given good "byte" to the stern planes
The motors are very powerful. In fact I reduce the power available at full bore from the TX to a more adequate level.(perhaps an alernative set of gears...??)
One thing worries me and it is the fact that the motors got quite warm during operation.(Gear mesh has been cared for and adjusted for some minimum "click-clack")ESC is a Mtroniks 20 amp type and the props are 35mm dia brass from Caldercraft (rivabo) left and right handed.I do not know about the pitch but it has to be not high because the boat shows good pickup of speed but not high speed.They rotate inward.
I am using now lead acid batteries (6V 3.0Ah) placed in front of the SD lying flat.The duration is about 30 minutes being cautious with the throttle.
I am planning to upgrade to NIMH batts in 7,2 3800mah rigged in parallel which will give 7600 mah and the weight will be close to what I am using now (625 grams).Also with the increased voltage the snort pump will be somewhat faster.
In my view this "big" capacity SD could be equipped with a somewhat bigger diameter vent valve because it is problematic at times to flood the tank completely and always that odd bubble remains upsetting your careful trimming.You have to force it out of the ballast tank using forward and back motion using the throttle and I am pretty sure that with a bigger size it won´t be such an issue.
I resorted to glue with RTV the gas valve in place after some problems with the set screw that fix it in place.Never a single problem since then.
I have changed the control surface pushrods from the SD to the control surfaces replacing them with carbon fiber solid rods in 3mm dia(the type commonly used in aerobatic kytes) they are much more rigid,weight next to nothing and are impervous to water.Moreover I think it does not make much sense to install an electronic leveller without having a really good mechanical link.
My installation of the Snort system is based in common sense and in materials already known (as the gas line).Also the centering of the boat has some points in common with planes being critical about the placement of the CG.The leveling of the ship in surface trimm (how the model sits in the water) are made using a calm water tank and a small bubble level both lenghtwise and sideways giving or taking foam and weight here and there until satisfactory equilibrium is found.It took about two hours in total.
Thank you for your interest Mr Merriman I hope we can have more feedback in the future.
I truly admire your work:
Jose

[He Who Shall Not Be Named]

Jose,

That was a careful and rather complete critique of the 3.5 mod 2 SD. Much appreciated. And it deserves a detailed response:

Yeah, you're right, there are some castings (I bet you're talking about the motor bulkhead) with a lot of ugly looking bubble-holes on one end -- a consequence of bad casting techniques. Since production of the early batches I've changed production methodology to include a dust down of the mold cavities with talc. That action reduces the surface tension between rubber and liquid resin, eliminating the catching of bubbles in the tool during the casting operation. So, that problem (cosmetic, not functional) has been addressed. I was taught the talc trick by SF modeler, Ron Gross.

We provide the 3.5 mod 2 SubDriver with an excessively large ballast tank -- we leave it to the end-user to either cram displacing foam into it to reduce the floodible volume (as you have done) or to physically saw off the forward end of the cylinder till the ballast tank assumes the proper size for the boat it floats.

We're sticking with the 3:1 gear ratio of the motors as that seems to be the best generic match for those operating the bigger sized models. However, as you observed, the gears in the wet do water-hammer a bit. For that reason, this year, I'm re-engineering the motor bulkhead to place the gears into the dry side of the motor-bulkhead, significantly reducing unnecessary loads on the gear train, reducing the heat experienced by the motors.

We're sticking with the 1/8" size vent valve hole. But, there are a few tricks you can employ to speed up the rate of ballast air/gas released during the flood: periodically (perform during the pre-mission, mission, and post-mission checks) place a drop of oil onto the vent valve rubber seat. And (pre-mission), through the open holes in the bottom of the ballast tank, shoot a spray lubricant onto the upper portions of the ballast tank, this reduces the surface tension between the plastic and the water in the tank reducing hang-up of bubbles within the ballast tank as it fills with water.

Thanks again, Jose. Good points raised, and stuff I need to hear to improve the product.

David,

[Ironhorse]

T-Class "cosmetic" additions and 3,5 SD bugs

Hello Mr Merriman and all fellow submariners:
First of all I would like to comment about the leaks experienced in the 3/16 motor shaft seals.After experienced fogging after about 1 hour of running I decided to inspect for leaks.After conecting my blow tube I found a good leak in the right motor shaft.No way I have to dissassemble the whole thing to reach the problem.To my surprise I found the rubber seal intact after much inspection but what gave me the clue of the problem was that the bronze bearing which holds the rubber seal in place came hanging in the motor shaft so telling the tale that the seal become unseated when the bronze bearing somehow vibrated loose from its seat.I measured the "gap" between the end of the motor case including the bearing and the surface of the bronze bearing and it gave me about 8mm of unsupported motor shaft.After some thinking I filled the void with some aluminum tubing of the right lenght and a thin rubber washer and avoiding this way the "unseating" of the bearing and the rubber seal.I have still to test the repair but I am fairly optimistic about the result.
I hope this imput would be useful for the designer.
Best regards:
Jose

[He Who Shall Not Be Named]

Thank you, Jose. The aluminum tube spacer is a viable fix. An easier one is to simply place a drop of CA between the Oilite bearing and the resin bearing foundation, after positioning the Oilite up to where it nearly pushes the cup-seal up against the after end of the housing.

Good sleuthing there, and thanks for the details of the fix you employed.

David,

[Ironhorse]

Weather beaten T-Boat

Hi everybody:
:wink: First give my thanks to Mr Merriman for the tip about the use of silicone oil (I used 20W) in the vent valve and silicone spray into the ballast tank to speed up the flooding. It has improved things greatly.The fix commented in the previous post about the motor shaft seal looks effctive.No more leaks detected in that place.
However and perhaps caused by the heat of the motors is possible to see condensation in the inside walls of the WTC after about 30 minutes of running.NOT a leak.The same thing happens to my other sub (A Trumpeter Seawolf) and NEVER a leak has been detected.
I would like to show you some pics of the boat after receiving some weathering using airbrushed darkened and lightened tones and also the addition of the scum line.
Hope you like it
Best regards to you all:
Jose