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Returning to modelling.

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Fourtyfreak:
Hi all,


Semi-newbie here, returning to modelling after about 20 years out. I’m a mechanical engineer by trade so long terms I’m looking to make a steam powered launch of some kind, not sure exactly what yet, but that seems like it’s right up my street.


First off however, I’m gradually collecting the resources for a Springer Tug. I love the idea of one of these, and I’ve set myself the challenge of making it out of as much recycled stuff as possible. I dusted off my old 27Mhz Acoms RC gear over the weekend, I trust these are still OK to use legally in the UK.


I also have a Ripmax Spirit 600 motor which I’ll hopefully be able to use. I’ll need new batteries as my old Nicad pack are bound to be shot. Would Lipo’s be OK?


All the wood for the build is coming out of the work skip. I’ve done 9mm ply for the sides, but wondered if hardboard would be OK for the bottom skin. (With loads of waterproofing obviously.)


Anyhow, apologies for all the questions, but things have changed a bit in the past few years.


Cheers


Paul

Tug Fanatic:

Paul

Welcome.

27Mhz is still legal in the UK  :-))

Springers are slow models and a such work best with a motor that can turn a relatively large (40mm) prop relatively slowly (5-6000rpm max & probably 3-4000) whilst not using too much current nor generating too much heat. I do not know whether a Ripmax Spirit 600 fits this profile.

Motors do not care what sort of battery you use A volt is a volt etc etc.. A Lipo would be fine but be aware that most Springers use 6v and that going to 7.4v (2S Lipo) will increase the wattage and heat generated by around 50%. 

9mm for the sides sounds great but I would not use hardboard (nor MDF) in any model that I put time & effort into building. I am sure that you can, and someone might tell you that they have, but I wouldn't.

SailorGreg:
Welcome Paul, and I hope you enjoy building your springer.  Hardboard would need a LOT of waterproofing (and rapid attention to any scratches or dings) to ensure you didn't suffer failure later in life.  Thin ply would be better, or I planked mine with 1/8" balsa planks laid athwartships, purely because I had the balsa and was using up stuff I had to hand (and a good coat of epoxy resin to strengthen the balsa is pretty important).  If you are viewing this as an experiment or trial run, you could try the hardboard if you accept you might need to build another hull in the future and transfer the superstructure and running gear into it.  If it was me I would saturate it with thinned epoxy resin inside and out.

As for batteries, LiPo will be fine but you will find you need a fair old chunk of ballast to get the hull sitting nicely which is why most opt for a good old-fashioned lead acid to provide some useful weight in the hull.  I use a 7Ah 6v one which pretty well does the dual role of ballast and propulsion. 

Have fun, and let us all know how you get on.
Greg

Fourtyfreak:
Hi,
Thanks for your replies.

It's nice to know that my old 27Mhz gear is still usable, though I've my eye on the Turnigy 9X as a future upgrade.

I know what you mean about the hardboard, I'll see if I can scrounge up some thin ply for the bottom skin. Or possibly steal radiojoe's idea for Gala Girl and redesign the springer with flat panels and use the 9mm ply I have already scavanged. It'll make it a bit of lump, but if I'm going to need loads of ballast anyway, it might make more sense. I really do like the challenge of making things out of scrap. We'll see. :-)

Thanks for the advice on the batteries, I'll see if can lay my hands on a suitable lead acid.

I'm currently modeling a few different ideas in SolidWorks. (One of the perks of my job) If it turns out OK, I'll post them on here for everyone else to play with.


Once again, many thanks for your help, it's greatly appreciated.

Paul

SailorGreg:
The Turnigy 9X looks a fine piece of kit.  However......
If you expect to have more models in the future and are planning to use the 9X's model memory to allow it to be used with all your models, beware!  The 9X has a problem in its software (or firmware, or some-ware), acknowledged by Hobbyking, that it cannot bind with more than one receiver at a time.  If you use the transmitter for multiple models, you will have to rebind the receiver every time you swap models.  This is a pain in the rear end, to say the least.  If you plan to only ever use the 9X with a single model, it will be fine.  But if you want a transmitter for several models, the 9X is not for you.  There are other transmitters that will do the job, such as this one that I have ended up with.  It is only 6 channels rather than 9, but that should be plenty for a springer (I use 3 - steering, propulsion and lights).  Hope all that helps.

Greg

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