Posts: 158
Joined: 1/12/2003 From: WITHAM, UNITED KINGDOM Status: offline
Checked out all the radio gear this weekend BUT it's apparent that the "Standard" Servo is NOT Man enough as a Sail Arm Servo. Didn't expect it to cope. It blew a gale here, first strong winds since before I started building Kon Tiki. I could position the sails in a breeze but in the gusts, the servo arm swung round out of control. Anyway, the geometry is correct so not a wasted exercise. There are a couple of "Monster" Servo's on eBay, so hopefully Kon Tiki will get Her maiden voyage this coming weekend!
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Steve Carey/G4MJW http://www.kon-tiki.freeserve.co.uk
Posts: 158
Joined: 1/12/2003 From: WITHAM, UNITED KINGDOM Status: offline
After much experimenting and testing, this is how I am controlling the Sails.
A standard Servo is no where near powerful enough, so I have picked up a CS-650 BB FET Jumbo Servo 20kg (44lbs) torque on eBay for $35! However, this is a bit of an "over-kill" !
(A have a better quality image on my Kon Tiki website)
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Steve Carey/G4MJW http://www.kon-tiki.freeserve.co.uk
Posts: 158
Joined: 1/12/2003 From: WITHAM, UNITED KINGDOM Status: offline
Still waiting for blocks to arrive . . . . can't wait any longer! I've now set up the "Sail Winch" and used "Brass Eyelets" in place of pulley's/blocks. The drag is actually very low. The JUMBO servo could move a house.
Grand Launch is on Wednesday!
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Steve Carey/G4MJW http://www.kon-tiki.freeserve.co.uk
Posts: 158
Joined: 1/12/2003 From: WITHAM, UNITED KINGDOM Status: offline
Summer is coming to an end, already. A few weeks ago, the sky was blue and daily temps reached an all time record for the UK of 100°F. It's barely 65-70 at the moment and dropping daily.
Just 7 miles from here is a town called Maldon, which is on the river Blackwater. There is a dedicated Model Boating Lake. It is salwater, so would rarely freeze in winter.
Posts: 158
Joined: 1/12/2003 From: WITHAM, UNITED KINGDOM Status: offline
Today was launch day. Kon Tiki sails very well, infact Her performance is excellent!
Few slight problems requiring modifications:
Kon Tiki turns very slowly. The Rudder surface area is too small. Rudder Needs increasing by 50%.
The 3 halyards are of thin yacht rope of the non-pre-stretched variety. The sail geometry completely changes with high wind loading. Need to be replaced with cycle brake wire or pre-stretched rope.
Kon Tiki although a large boat, is very light in weight. Perhaps too light. In strong winds she still sail straight and with little or no tendency to capsize. However She want to nose dive into the water thus bringing the aft end out high and also with little rudder left in the water. Reluctantly, I will try adding some ballast. None was actually require to trim her as she sits perfectly in the water.
Any suggestions on this point will be most welcome.
Well now you know where to stow the rum!!! You might try to find some Spyderwire(kevlar) fishing line to upgrade those stretching halyards. Yeah not tradional but no weight and no windage; (#6 mono diameter for 50# break rating) cantilever or balanced rudder for keeping the tiller loads down????? keep fine tuning looks good!
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