manual or operator folding tail

[kitestrings]

I started some this discussion on midwoud1 "Active Pitch Control" http://www.fieldlines.com/index.php?action=profile;area=showposts;u=63546.  Frans was kind enough to offer some great suggestions, but I'd like to solicit a few more ideas particular to a folding tail design (and not jack his post any further than I have).

I'm generally not looking for control so much as a means of shutting down the turbine manually or via remote actuation when/if needed.  Our Sencenbaugh has a cable to a small hand winch that cranks the tail around.  Seems simple enough.  In practice, the weight and restriction of the cable (e.g. lubrication and or dirt, icing, corrosion) can all interfere with the normal furling operation.

A similar approach that Frans shared:
http://www.thebackshed.com/windmill/blog.asp?blog=1

My goal has been to a have as simple an approach as possible that does not interfere with the furling design.  My current bias is to put a ratchet on the hinge pin.  The strain relief for the SO cord would terminate on a spring loaded pivot plate.  A tug on the cord would set the ratchet and the wind would do the rest.  The draw-back is you couldn't shut-down at will, or in low - to moderate winds.

Other possibilities:
A chain driven motor actuator (like a skylight operator) pushes the tail off rest stop
A motor actuator with a key slot (Fran's suggestion)
A mini-pump and hydraulic cylinder, toggling the cord pumps the fluid (like a brake purge pump, or Greenlee tool)
A pneumatic cylinder, small pressurized reserve tank.

Here's what we're working with.  The tail hinge is thick walled AL.  It has bronze radial bearings and a greaseable needle roller thrust bearing.









Thnaks in advance for any thoughts/experience.  ~ks

[Flux]

All my machines have had some form of manual shut down ( except a couple of tiny ones)

All stop the machine by turning the tail at right angles. I have to admit that here high towers are not possible and I can see that a 100ft of cable may cause my devices some issues.

Similarly in some conditions of cold and ice I can also imagine problems with freezing.

The ideal place for shut down cables is down the centre but machines without slip rings normally have the connecting cable here. The various sliding sleves and contraptions needed to do this without going down the centre do need greasing and maintenance and in some conditions I could imagine problems. I am far more comfortable with the slip ring machine that has a control rope up the centre. That one is built backwards and the weight on the control rope holds it into the wind and controls the furling point and can be adjusted from the ground. The weight of 100ft of rope here would be no issue but in certain climates there may still be an issue from icing.

My schemes have been part of the furling mechanism and not an over ride on a gravity furling scheme.

I dread active things up in the air with associated connections and potential failure but Frans' scheme does look to have promise.

I think your climate will be the deciding factor, what works in one area may fail in another. If your climate is such that a needle roller will survive then you may have a few options.

Simplicity is the ideal but although all my schemes work they are really not that simple except the slip ring machine ( complexity is then transferred from shut down to added complication of slip rings). I am inclined to suspect that at 100ft the dangling wires and weight start to be a significant issue and the slip rings may not be such a bad idea but they have to be built properly or they become a pain.

Flux

[midwoud1]

Choice of concepts.

) Pull-line, centerfeed through masttop , with sliprings like Flux mentioned.
  Simple and efficiënt. Pull-line Dyneema carbon 3,5 mm lightweight extra strong.
) Actuator on top ,sliprings with 2 extra rings. ( forward and reverse )
) Actuator with slider system. (free furling )
) Actuator with motion controlled tailboom, hand / automatic.
) Actuator Push system , no contact tailboom at retract ( free furling )
)  Passive pitchcontrol with flyweights. Still needs tailfold retract. (New Jacobs )
) Active-pitchcontrol. Mechanical complex. Extra work , Need machining,
   but we have things under control : Blade angle, adjustable at max. volt, Ampère , Rpm, and
   stator temperature. ( Hand / automatic ) improvement with failsafe.
) Hydraulic handpump and mini ram-cylinder with 1/4" HP hose ( twist problem )
   unless we use a swivel coupling on top of the mast.
  I had it a time ago with  a disc-brake mainshaft.
) Pneumatics , I don't know how it behaves with condens water and low freezing temperatures.

  - Frans -

[kitestrings]

We're not planning on slip-rings on this machine.  Lot's of discussion on this element, but at the end we decided on a 'twist cord' (SO cord).

) Hydraulic handpump and mini ram-cylinder with 1/4" HP hose ( twist problem )

I haven't ruled this option out, nor just a simple pull cord.  I think the twisting could be overcome by having the pump mounted above the yaw point, and using the twist cord as a means of actuating the cylinder.  One draw-back is that everything hydraulic is heavy.

The other option I haven't let go of is a ratchet.  Literally a 1/2" drive, flex-head ratchet.  The drive could engage in the fixed hinge pin.  I have a long handling type that has a "free" position between CW and CCW settings.  A link to this thumb-selector should allow it to be engaged from the twist cord.

~ks

[kitestrings]

Flux,

I'd be curious what you concern is with the thrust bearing.

Originally, I'd intended to have bronze thrust bearings for both the yaw and tail.  That is still the plan on the yaw tube between the steel flanges.  On the tail the loads is quite low, and arguably a higher percentage of the load is carried by the radial bearings.  I was also concerned that with a comparatively soft material (namely aluminum) on the top of this bearing, that it could become the wearing surface.

We are  in northern VT so temperatures vary greatly, but we do not have salt contributing.  The pin bearing is recessed into the base of the hinge assembly for weather protection, and the grease zerk angled in to the center of it.  It is rated for -40 degF to...something like 140-150 degF.  It will have only about 2% of its rated load in an axial direction.

kind regards, ~ks

[Flux]

Sorry, I didn't read your post properly, I thought you were going to use needle roller bearings for the tail hinge. As thrusts they should be ok if you keep the water out.

For the hinges they again may work with herdened and ground pins and perfect lubrication. The problem as I see it is that needle rollers leave one critical component of a bearing outside of the control of the manufacturer. With offset thrust and reciprocating load and poor lubrication and likelyhood of water entry they will normally groove the pins and become notchy and lock up.

Seemed like a simple solution when I tried it but it didn't work out. As thrusts they may be fine, especially if you have the type where the roller track comes with it.

Flux

[kitestrings]

This is the thrust bearing that I'm planning to use.  It is paired with hardened, and finely finished (16 microns) washers.  It is recessed into the bottom of the verticle hinge piece for weather protection.  The temperature rating is actually -40 to 248 (degF)