Spirals.

Marquis DeCarabas · Post by **Marquis DeCarabas** » Wed Jul 09, 2014 9:47 am

Right - I've got planning permission from the Trundle for a spiral at the bottom of the garden - she wants one for her Darj engine (and as I'm in the process of acquiring an(other) FR engine it seems appropriate.

Does anyone have any tips that they'd like to share - things like radius and rate of climb.

Post by **Andrew** » Wed Jul 09, 2014 10:20 am

What fun! Guess in part the answer to your question depends on what length trains you want to run. Early indications are that RH locos will pull three heavy-ish wooden coaches round 3'6" radius curves on about 1 in 100, although I'd go easier on 'em if I could. Maybe they'll pull more - I haven't tried yet... Reading Ian Stock's stuff indicates that he's had similar results.

Happy building!

Andrew.

TonyW · Post by **TonyW** » Wed Jul 09, 2014 10:21 am

It is not usually going up that is the problem, it is coming down.

Marquis DeCarabas · Post by **Marquis DeCarabas** » Wed Jul 09, 2014 10:49 am

The spiral will be part of a circuit, with one exception (Tony Sant 'Winifred') all locos are RC.

If they go round the circuit clockwise then, like an Escher painting they shall always be going up the spiral.

Due to the layout of the garden, there will be a descent into the spiral, so there is a fair chance that excess speed will be blended out IYGWIM.

Length of train is variable, but I expect the standard train will be between 5 and 7 feet.

dewintondave · Post by **dewintondave** » Wed Jul 09, 2014 10:56 am

There was recently a write-up in the 16mm facebook group about a spiral.

Marquis DeCarabas · Post by **Marquis DeCarabas** » Wed Jul 09, 2014 11:05 am

Indeed - I was casting the net further, as it were. I made a note of the appropriate measurements somewhere, but I think they're hiding on my smugphone.

LnBmad · Post by **LnBmad** » Wed Jul 09, 2014 4:39 pm

I too have been thinking about a spiral. Please let us know how you get on MdC.

laalratty · Post by **laalratty** » Wed Jul 09, 2014 8:38 pm

I suppose it all comes down to maths in the end, ie with a 1 in 100 grade to get 20 cm clearance you will need 2000cm run, and as with all railways the easier the grades and curves are, the easier life will be.

dewintondave · Post by **dewintondave** » Thu Jul 10, 2014 7:39 am

I like to use 8 ft radius curves on my garden railway when I can. At 2% grade a 8 ft radius will give a 1 ft rise per complete revolution of the spiral.

My 180 deg return curve is only 3 ft radius but is steeply downhill this cancels out the drag of the tight curve. If you were going to run in one direction only a tight and steep spiral will work.

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