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Towline length for Westwings amethyst

Started by ronstv, August 04, 2013, 16:33:34 pm

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ronstv

What's the best length towline to use for the amethyst. I have installed micro rc.
No elastic just a pure towline.
Thanks. 49" span. 5.5oz all up weight. Tissue and dope covered.
XH558 lover & follower

Michael_Rolls

Quote from: ronstv on August 04, 2013, 16:33:34 pm
What's the best length towline to use for the amethyst. I have installed micro rc.
No elastic just a pure towline.
Thanks. 49" span. 5.5oz all up weight. Tissue and dope covered.

Provided you use a light enough line it ought to be able to handle 100-120 feet or so easily. It's only a bit lighter than the A1 class which uses a 50 metre (164 feet) line. A really light line is imprtant though.
HTH
Mike
Properly trained, a man can be a dog's best friend

ronstv

Thanks mike,
Just looked at line and its .28mm 10lb breaking strain. Looks really light..used a very light curtain ring and a small piece of ribbon.
Any more tips, I've never towed a model up before
Thanks


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XH558 lover & follower

Michael_Rolls

10 lb breaking strain is unnecessarily strong - that would need the  model to pull around 30G to break it - the model's wings would fall long before that.
Towing such light models is a bit of an art rather than a science and the CG/towhook position relationship is important. If the model weaves from side to side it is an indication that the hook is too far forward (or the CG too far back - same thing in this respect) but can with care be coped with. A towhook too far back is bad news - the model will effectively want to do a wingover - don't try to correct it - just cast off and cross your fingers
Mike
Properly trained, a man can be a dog's best friend

Patmac

Mike, are you talking about F/F or RC glider towing ?
With RC you're not relying on the S&L trim so can adjust the climb as necessary during the tow.  I used to have the hook just behind the cg for a good positive tow & saving the towman having to run too hard in light wind conditions.

Ron, you don't intend towing & controling at the same time are you ?
It can be done but isn't a good idea, it's best to use a bungee in one man glider launching.

IMO 10lb BS is probably OK for this model, I used to use 80 - 100lb for 100s & BARCS Open models & many serious comp fliers used heavier line than that. The actual BS of the line is reduced at the knot & also deteriorates significantly in it's useful lifespan. In his RC Thermal Soaring book George Stringwell reckons the BS is reduced to about 50 - 75% of the rated value at the knot.     
Pax vobiscum

Phil_G

Be very careful of anyone who is used to towing modern gliders Ron  -  he'll fold it, almost guaranteed!
You need to impress on your tow-man that its a 5 ounce model and finger tension is all it needs - if he feels its pulling at all hard then he needs to slacken off even if that means running back towards the launch spot.  Even in flat calm it should walk up after the initial stretch is taken up.
And dont forget the video!!
Cheers
Phil

Michael_Rolls

As Ron seems to be talking of towing th emodel himself, I assumed this is a F/F model - apologies if I am wrong.
Mike
Properly trained, a man can be a dog's best friend

ronstv

Thanks for all the info guys.
Sorry for the confusion, I was intending to get a helper to tow it for me.
It flew well up the slope but fancy a bit of flat field flying. I would love to try and ride on a thermal just from a flat field.
It does seem to just float on and on as its so light and has generous under-cambered wings.
Phil, ill do my best with the video.
By the way, I've used Hitec HS-35 servos. Blimey they are small. Full closed loop.
320ma lipo and a home made 5v reg with a LDO 1a reg. done lots of tests and seems good.
XH558 lover & follower

Michael_Rolls

Ron
As Phil says, do make sure your helper realises how much more delicate this model is than your 'average' R/C glider. All the best with it
Mike
Properly trained, a man can be a dog's best friend

ronstv

Amethyst flight earlier today.
XH558 lover & follower

Michael_Rolls

Properly trained, a man can be a dog's best friend