Rubber Power

[Ian JopsonParticipant @ianjopson21383]

I've just come into possession of an old (1950s/60s) damaged motor cruiser that was designed for rubber power. This is long since gone and I was wondering if the appropriate type of rubber banding can still be obtained?

Note, the model is from a Modelcraft kit, a bit rough round the edges and a hole in the hull. I'm hoping to get it running again for the grandchildren, or at least looking presentable.

[Ian JopsonParticipant @ianjopson21383]

[Colin BishopModerator @colinbishop34627]

Ashley has built a rubber powered model, a Bowman Aeroboat – he should be able to advise.

Colin

[ashley needhamParticipant @ashleyneedham69188]

Indeedy I have. I used 1/4 inch flight rubber, from a model shop (no longer in existence!).

The secret is to lubricate the rubber with glycerin, as this stops it drying out and also stops it sticking to itself when knotted up, but keep the dust off.

Rubber motors should be broken in , by gradually building up to the full amount of winds, by half-winding, then 2/3 then 3/4 and so on.

Mine had 20m of rubber…it was very powerful! Colin is almost right, the first one I made was indeed a Bowman copy, but the second incorporated several improvements. It also meant I had to be quicker running round the pond.

Ashley

[Ian JopsonParticipant @ianjopson21383]

Ashley, did I read that right, 20 metres? Seems a heck of a lot, but my boat is only about 15inches long and I only want it to potter across the pond, so probably won't need that much. I've been examining the model and think perhaps I should start a restoration thread, there's more to do than at first glance.

Thank you for the advice, by the way, much appreciated.

[Dave MilbournParticipant @davemilbourn48782]

Ian

I just Googled "Flat rubber strip for model aircraft" and found this website Flat Rubber Strip

Dave M

[Ian JopsonParticipant @ianjopson21383]

It looks as though Hobbies do it too, in small amounts. I may take a run up there on Saturday as its only about 3/4 hour away.

[ashley needhamParticipant @ashleyneedham69188]

Ian. Yes, the boat was 1.2m long and had two rubber motors in it. The anchorage at the bow was literally at the bow and the prop shaft was reversed so at to put the gearing right at the stern to maximise rubber length. It was very fast….

yours will likely only have a motor length of about 12 inches.?

Ashley

[Ian JopsonParticipant @ianjopson21383]

Thanks Ashley, I was thinking perhaps two lengths of the hull would suffice.

[ashley needhamParticipant @ashleyneedham69188]

I think you will need more than that…I would buy at least 6 lengths if not 8..

Ashley

[Ray Wood 3Participant @raywood3]

Maybe worth looking up winding a rubber motor from an aero modelling source it's like a multi strand platt, rather than the big rubber band as the small Keilcraft aeroplanes. Hence the multi strands required.

Regards Ray

[captainslogParticipant @captainslog]

ian i just built a ray malmstrom hollandaire libel crop duster. the length of prop wire to motor peg was 11" i put (as per plan) 60" rubber 1/8" flat tan in there. 3 loops pre tensioned. so ashley is not far out. and dont forget those planes are 1/16th sq stringers and balsa spacers. pre tension your rubber before fitting and lube it well. my lube is glycerine and unscented household soap.(used to be a large block of green fairy for the washboard, gran used to go nuts when it dissapeared) also invest in winding stooge if you want to go alone. you need to wind that rubber in from full stretch slowly walking in towards the model as you wind. good luck with that lol

keith

[captainslogParticipant @captainslog]

Hi Ian, I just finished a hollandaire libel rubber power airplane by ray malmstrom. yes its a plane and the construction holding the rubber(fuselage) is 1/16sq balsa and 15" long covered in tissue and dope. from the prop wire to the dowel holding the rubber is 11". i used 60" of 1/8" flat brown rubber in 3 loops. now iff this construction can hold 3 loops of stretched rubber (slowly walking towards the model as you wind) and survive then ashley seems to give you a good idea of length required. as regarding lube its a must. i use 2/3 glycerine to 1/3 unscented soap melted down. it used to be green block of fairy soap used on the washboard for clothes. gran used to go nuts when 1/2 a bar went missing. you can find decent rubber on mikes flying scale models forum or the free flight supplies sight. hope this helps

keith

[Ian JopsonParticipant @ianjopson21383]

I've managed to put together the instruction sheets for the boat (they were in pieces, and a very sad state). These imply that a "double strand" rubber should be used. I can't see that offering enough power to get across a pond. Similarly, I've been investigating the model over the weekend, and thing there could be difficulty getting at the bow anchor point for the motor hook. It's only accessible through a hatch about 3/4 inch square, and it's dark in there.

[ashley needhamParticipant @ashleyneedham69188]

Ian. I have seen these sorts of things use rubber that you would have bought years ago for a catapult (square section) and so only two strands might have been needed as it would have been quite thick.

Rubber banding is cheap enough, so a few experiments might be needed to see exactly how much you will need. I remember trying my Bowman lookalike on just two strands and it ran for ages, but at a really low speed (in the bath)

A "pusher" bit of wire with a bend at the end might be needed to thread this in. I small torch and a mirror might assist (depending on the room)?

Ashley

[Ian JopsonParticipant @ianjopson21383]

Ashley, I was thinking I'd need a torch and possibly something like a crochet hook. At present I'm not even sure the hook is still in place.

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