tRUMPETER 1/200 BISMARK r.c fit
To moderators, if you feel this is in the wrong thread please feel free to move.
Project To design and construct a r/c system to fit in to the new 1/200 Trumpeter Bismark kit.
First buy the kit and look in the box, everthing that has been said about the kit is true, and more
we will update the thread as we progress,even when we get it wrong ?
Saturday evening, what a way to get away from work, build a model boat ?
up date, trial fit deck and mark in hull access areas,
First assembly and trials will be with twin screws, independant motors to test handling, will trial fit 3rd shaft later
Open out the proptube exits with a file
Trial fit the tubes in place
check equal angle on both tubes
Drill our the rudder tubes
Turn up 2mm bearings and push fit into drilled rudder tubes.
Assemble twin tiller arms and locking wires.
Trial fit in to rudder tubes.
Drill centre of rudders
Fit rudders on to shafts with epoxy
ensure all is central and square, wait for epoxy to dry.
Open bottle of red wine and go and relax
the way to insert straight shafts to rudders and glue with epoxy is not going to last.. I'd say it will free turn in just anout one or two runs..
I you insist to use the original rudder then one way is to drill a 1mm hole on the rudder surface right into the shart and insert a 1mm steel/brass rod ... nevertheless, the original plastic rudder is not meant for R/C running for such a boat size...
Today project, how to spend a sunday
Drill out the A frames 2.75 mm
Fit a 2.1mm ID brass bearing in to the frames
Trial fit in to the hull with pattermakers wax
Fit cast brass 25mm 2mm 162 type warship props to the shaft with
lock nut and nylon washers
Fit 2mm shafts in to the hull with wax, and lose fit A frames,
in to hull to ensure they line up and run smooth
(will add oiling tubes later if run is a success)
Make a motor mount from hardwood and vacform in 1.5mm Hi Impact styrene
Sand to fit in to the hull bottom and line motor up with shafts
Trial fit motor in mount and temp hold in place with
D /S carpet tape for the test run. was going to use 108s to ease lining
up problems but have concerns will not have enough tourque for a heavy
boat with small props
Fit 2mm / 2.3 MM EXL couplings and lubricate with vaseline.
Repeat with opposite side.
Temp fit rudder servo in place with servo tape for the test run.
Make pattern for a battery boxe and vacform x 2 in Hi Impact plastic.
Wire up and fit 2 x 3800 ah Nimh packs
Test in pond, it takes 3.8Kgs lead ballast to bring to bottom of waterline,
this is some very heavy boat.
Fit 4 channel radio with 2 x 10amp ESC and rudder servo, bench test all.
Lightly lubricte the bearings with teflon so none gets on the boat,
Put batterys on charge and wait for the day to warm up and off to the
lake this afternoon.
Have coffee with shot of scotch ready for anti freeze purpose only.
I don’t know if we get to help with the design or not (your build here is great marketing regardless) but here is some unsolicited thoughts and pictures.
Why not vacu-mold the motors, battery trays, and radio box as one piece instead of separate? (example below)
Detailed metal rudders and R/C components, maybe larger rudders if needed.
Simple turrent animation (as previously mentioned).
Coffee anti-freeze! Awesome.
Follow up from the test run
It was a lovely day but so cold, had to break the ice on the water first.
The long prop tubes need some support on the inboard end as they vibrated when under power, so a quick fix was made with some plastic strips.
It is now back to the work bench, The trials were not a great success, this is a very heavy ship and the props do not deliver the power to drive her at acceptable speed, looks good on the water, but she has no reserves of torque, so in any breeze she would struggle a bit.
Differential steering was slow, but again in any breeze she would be a hand full, of more concern to me was that she had no “brakes” at all stopping distance we 3-4 boat lengths and this would not be safe.
The 25mm 1292 type brass props have a pitch of 25.6mm, I feel that the cure will be increase the prop to 30mm, but the problem will be that a prop this size will have a M4 shaft size.
That will not be acceptable as the 4mm shaft dia will not fit in the A frames or the exits in the hull. I will try making up a stainless steel shaft on 2mm with an adaptor on the prop end to convert to M4.
I may also try to fit a prop tube with roller bearings at the inboard end as a experiment while I am waiting for the shafts to be produced, and play around with drive only on the centre engine so see how she handles.
Apart from the power problems she ran very well and looked most impressive on the water. With a third engine fitted this will give a bit more power and the twin rudders will be more effective as the will be in the wash of the centre engine, but this will make the design more complex and expensive with the separate drive to the centre engine and this is not the brief we have from the customer.
As an aside the “anti freeze” coffee was the best taste ever, it was VERY cold on Sunday, and when you drop the little allen key in the water, you know it will be hard to find when you roll up your sleeve have to start rooting around in the bottom of the pond.
More to follow when the new parts arrive, and I get some time in the workshop
I may make the mounts in one piece later, but we have tried out three different motors up to date, two couplings, and now shafts, seperate mounts are sensible at this early stage, also we may cast a scale rudder, or a oversize one, but then we may need to increase the size, this is why we have trials and test run first. The shafts will be more the man enough for this boat, we have runn 2mm shafts in far larger and heavier boats before, as long as they are well supported with good bearing.
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