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[neilthebus]

I picked one of these kits up to-day as a first attempt at building a model boat kit. My first couple of attempts have been re-building and converting RTR boats, ie a Dickie tug.

Is it feasible to make the Rainbow a powered model with basic r/c ie to make it go and steer.

The deck is a one piece moulding that is supposed to be glued to the lower hull. I presume to convert the model to a powered one I would need to make some kind of opening in the deck to access the mechanical gubbins.

Any advice would be gratefully received.

Thanks. ??? ???

[White Ensign]

Neil, you can do every model r/c. Though, if you want to convert this kit into, mark the area of the superstructure on the deck and cut it out with a jigsaw. Mark the waterline on the hull, put it in the bathtube and add weight until it`s on the WL. Then take all the items out and put them on the balancecounter. That`s the weight you may add for Nicad, Electronics, propulsion and superstructure plus fittings. Then put the fittings on the counter and the difference is, what has left for your the foresaid first three items.
Sounds more difficult as it is- some of my boats are between 385 and 650 grms. in total, fully r/c.
Don`t hesitate to get in touch with me if you have any further questions.

Jörg

[neilthebus]

Thanks Jorg

Gives me a excuse to practise my GOGS status and recover from all those teenies on the bus!

Do you have any suggestions for what equipment to put inside. Its not a very big model so I would imagine it wont need a big motor or battery pack

[White Ensign]

Neil, about the size I would recommend 6 Volts (fair enough as you don`t need too much power in that boat). A micro-controller like (i.E.) Graupner Micro Speed 10 and a motor from Maxon or Faulhaber, which is an ironless type. The advantage of these motors: Their consumption is unbeatable. Have a look for a supplier in the UK. Decide a Motor with 6 Volts and about 8500 Rpm. The diameter of such an irolness motor is very easy to calculate: The diameter of the Prop plus 25%- then you will find a really good propulsion for it. Take 5 or better 6 cells NIMH with about 1200mAh. A motor like this will take about 250mAh max. which gives you a minimum of 3 hours of joy with that boat. I would recommend a prop with 25mm dia- though a motor with about 30mm dia would be good enough for it.If you need any further deatils, have a look under www.maxonmotor.com
However- first of all make a calculation with the balancecounter and then calculate the deadweight for deck and fittings. If possible, do weightwatching from the very start. Try to replace the wooden items like deck and superstructure and replace them by plasticard. Instead of a wooden mast take a lightweight-aluminium-tube.
As mentioned earlier- it`s not impossible- if you know how to do.

About the teenies in the bus.....- I am absolutely with you- as my son is age 13.... 
With your job Beta-blockers must be given every morning.....

Anyway- nothing can get us GOGS down!

It reminds me on a joke I have heard a while ago:
There was this business-man, taking the bus. It was overfilled with screaming teenies, though he decided to stay beside the driver.
He seems not to notice the roaring noise in the background, just doing his job- smiling. After a while the business-man had enough.
"How can you stand that awfull noise?", he asked the busdriver. No answer. He fighted again against the noise in the back and replied his question. The busdriver looked at him, smiled an stopped at the next buststop, selling some tickets and carried on. The manager took out a paper and wrote the question again on it. He passed it on the next stop to the driver. The driver grabbed the
paper and left an answer:
"Sir, I`m neither on drugs or pills. I am not foolish anyway, but I am def since birth. It was the reason why they had given me the job and gave me an extra of 25% as nobody wants to serve that line".

Jörg

[malcolmfrary]

Looking at the size of the model, I would consider just butchering a cheap servo to provide both motor and speed control, and run the lot off the radio battery.  5 AA re-chargeables should give a long enough run.  Its also probable that you wont need miniature components (radio, servo) but you will probably need to sort out your own arrangements for the propshaft and rudder if these are not provided.  It amazing what you can do with those drinking straws from "box" drinks, cotton bud tubes, and brass wire from the model shop.
Just keep the weight low in the boat , and try to make sure that there is some sort of wall around the hole - fialing that, make it a good fit and use a smear of vaseline around the lip of the hole to stop water getting in that way.  And dont forget the freeing ports, so that the water that does get on deck can get off down the outside.

[barriew]

Neilthebus

I have actually made this model - or most of it! I thought it would be an ideal introduction to model boats - wrong >:( I never really finished all the bits and pieces.

I had quite some difficulty just building it and never even contemplated motorising it. In fact I didn't build it until I had built other models and had a bit more confidence. I don't want to put you off, but equally I wouldn't like you to start this project and be put put off model boats building

Regards,

Barrie

[neilthebus]

Thanks folks.

As usual from what I have experienced so far with mayhem, lots of friendly helpful advice. I dont think I will be put off by it as I see it as a challenge.

Whats this about butchering a cheap servo to get both motor and speed controller? I've not had Further explanation of this idea would be VERY useful if anyone has the time to explain. 

Many thanks again

Neil

[malcolmfrary]

It's appeared in a few other threads, but -
In a servo is a control board and a motor.  The motor drives a gearbox that works a position sensing pot.  At the same time, it drives an arm to mimic the position of the stick on the transmitter.
If the gearbox part is removed, the output shaft of the motor is available to drive something else, but the drive to the pot wiill be absent, thus the pot will always be at the same setting.  What the servo is really doing is comparing the position of the pot against the position of the stick, and doing its best to make them agree.  With the drive to the pot missing, when the stick is central, nothing happens, but when the stick is moved, the motor drives to re-position the pot.  Of course it can't so the motor just keeps driving until the stick is re-centred.
The advantages are that it is very cheap, it takes up less space and weighs less than a standard servo, it plugs directly into the receiver and runs off the receiver power pack.
The disadvantages are that the deadband is very narrow, (but when do you want to totally stop the boat on the water?) and the shaft is a bit tricky to fit a coupler to (I use the flint spring from a dead dispoable lighter)
From the disadvantage of the narrow deadband comes the new facility of being able to drive the boat using the trim slider on the transmitter as an engine room telegraph.

[White Ensign]

Neil, Malcolm- turning a servo into a speedcontroler and power the boat with it isn`t a problem- but as said before: The deadband is really very narrow and (my experience) very sensitive if ýou drive with a view others at the pond. Though I decided to leave it as it is and went back to "professional" speedcontrolers and motors. Although the motors are very small and the are close to the maximum (or over it), take lots of amps and use to heat up.
Powering such a small modell is not impossible- but you should be aware of the technical necessarities to reach a controlable and good working model. Once done (and done wrong) who has the nerv and put all the items out and replace them? (To be honest- I am no exception). Once done- and once done wrong I leave i´t in the glass cabinet.

Jörg

[harrin]

Here is one very nicely built running model of Billing's Rainbow:
http://www.sulara.fi/images/modelexpo04_09.jpg
http://www.sulara.fi/images/modelexpo03_05.jpg

[mx5bob]

Hi Neil, there is another alternative if you want proportional speed control, try one of the G.W.S. indoor flight speed controllers,(but you will have no reverse, not many planes go backwards). they only weigh about 4 grammes, depending on capacity(2 to 8 amps), and include a B.E.C.,

Bob.

[neilthebus]

Thanks once again everyone.

Sorry about all the silly questions. Dont mean to be a pain and with regard to the servos, I just haven't had time to explore every thread on Mayhem - theres quite a few!!!!

Not sure that this model was a good choice for a first build after all. Think I might do another conversion of a Dickie tug!

I do appreciate all the replies and the effort folks have put in to them. A genuine thanks from me.

And for Jorg. I DO need something similar to Beta blockers every day - doctors instructions. I wonder why!!!