Hello all,
Been a big fan of this site for about a year now, but this is the first time I’m turning to the community for help....and I need it!
I have been building a modified version of the ky-ko fan using Julius de Waal’s plans (here: http://www.vapeuretmodelesavapeur.com/telechargements4/kyko-fan-stirling-jdw-complet.pdf ). Basically, the only bits taken from the plans are the dimensions for the cylinders and the width/length of the power piston and displacer. Everything else I’ve been designing as I go (which may not have been a good idea).
I’ve posted a few pics below. With the air valve removed (3rd picture below, knurled brass knob on underside of base plate), the motor turns over quite easily and smoothly. I’m trying to figure out how to post a video of this....it will turn over easily 15-20 times and then gently rocks back and forth to a stop. I’ve used ball bearings everywhere except for the connection of the power piston rod to the power piston itself.
The problem is, I can’t get the thing to run on it’s own...even with a blow torch.
I’ve checked the displacer side for air tightness using a rubber hose and a bucket of water. Seemed ok.
I’m wondering if my problem is one of the following:
A. Too much weight on the yoke for the displacer rod. The original plans called for some crafty milling of an aluminum yoke, which I don’t think I can do. I thus milled the brass/3mm stainless rod yoke combo shown in the pictures. It’s likely to be heavier than what the plans call for. I’m Not sure if this is the problem, however, since I also built another de Waal engine (http://www.vapeuretmodelesavapeur.com/telechargements4/s-stirling-vertical-05-01-02.pdf and picture 6 below), and it runs great despite the smaller dimensions of the power and displacer pistons and the relatively heavy (brass) yoke on the displacer rod in that machine.
B. Too much weight on the spinning axis (crankshaft). I have removed the counterweights on the crankshaft in photos 1 and 2 and replaced them with simple brass arms (5th picture), but I think this step actually made the problem worse.
C. Not enough weight on the spinning axis (crankshaft). In Photo 4 below, I’ve added four long spokes to the flywheel, each with weights on the end. The flywheel itself is solid steel. It turns true. With the longer spokes, it will turn over at least 30 times with a good spin by hand (and air plug removed). (Again, trying to figure out video...)
D. Too much heat getting to the power piston. I added 0.4mm gaskets under both pistons and the base plate, and a 1mm gasket between the displacer cylinder and (under) the base plate. The base plate is 12mm thick Aluminium, which can hold a lot of heat, while the de Waal plans called for a 4mm thick piece. I really hope this is not the problem because replacing the base plate will not be easy...and will mess with the overall design since the shaft for the flywheel assembly bolts into both the baseplate and the top plate (also 12mm Alu).
E. Not enough air getting to the top of the power piston. In the original plans, the top of the power piston is open. I added the brass top with the small slit cut in for the power piston rod (photo 2) since I thought it would look better. I can,t imagine why this could cause a problem, but....what do I know?
F. Dead space in the displacer cylinder. Yeah, there is a out 8-9 mm of dead space, the result of my modifications from the plans. I made the displacer piston relatively early, and it is a bit short.
G, Demons. The machine is simply possessed and I need the services of a wizard to exorcise the evil that lives inside it.
Any thoughts on this project would be greatly appreciated!
Q: Are there any guidelines on “balance”? For example, should the counterweights on the crankshaft be heavy enough so that, when at rest, the displacer piston is actually raised (ie pulled up by the weight of the counterweights)? In the other vertical Stirling I built (link above and pic 6 below), the displacer is still heavier than the counterweight, so at rest the displacer is at its lowest position.
Q: the plans in the kyko have the same diameter for both the displacer and the power piston cylinders. The moriya fan does not. Is this a problem for the kyko? Most other plans I’ve seen for vertical Stirling have smaller diameter power pistons.
Q: To address the dead space in the displacer piston (point F above), I am thinking about making the crankshaft arms longer. Plans call for a 28mm travel for the power piston, and a 38mm travel for the displacer. What if this were 28mm power piston travel and 46mm displacer piston travel? This would solve the dead space problem, but I’m not sure if the travel distances should be that different.
Thanks in advance for your time!
PMM
Been a big fan of this site for about a year now, but this is the first time I’m turning to the community for help....and I need it!
I have been building a modified version of the ky-ko fan using Julius de Waal’s plans (here: http://www.vapeuretmodelesavapeur.com/telechargements4/kyko-fan-stirling-jdw-complet.pdf ). Basically, the only bits taken from the plans are the dimensions for the cylinders and the width/length of the power piston and displacer. Everything else I’ve been designing as I go (which may not have been a good idea).
I’ve posted a few pics below. With the air valve removed (3rd picture below, knurled brass knob on underside of base plate), the motor turns over quite easily and smoothly. I’m trying to figure out how to post a video of this....it will turn over easily 15-20 times and then gently rocks back and forth to a stop. I’ve used ball bearings everywhere except for the connection of the power piston rod to the power piston itself.
The problem is, I can’t get the thing to run on it’s own...even with a blow torch.
I’ve checked the displacer side for air tightness using a rubber hose and a bucket of water. Seemed ok.
I’m wondering if my problem is one of the following:
A. Too much weight on the yoke for the displacer rod. The original plans called for some crafty milling of an aluminum yoke, which I don’t think I can do. I thus milled the brass/3mm stainless rod yoke combo shown in the pictures. It’s likely to be heavier than what the plans call for. I’m Not sure if this is the problem, however, since I also built another de Waal engine (http://www.vapeuretmodelesavapeur.com/telechargements4/s-stirling-vertical-05-01-02.pdf and picture 6 below), and it runs great despite the smaller dimensions of the power and displacer pistons and the relatively heavy (brass) yoke on the displacer rod in that machine.
B. Too much weight on the spinning axis (crankshaft). I have removed the counterweights on the crankshaft in photos 1 and 2 and replaced them with simple brass arms (5th picture), but I think this step actually made the problem worse.
C. Not enough weight on the spinning axis (crankshaft). In Photo 4 below, I’ve added four long spokes to the flywheel, each with weights on the end. The flywheel itself is solid steel. It turns true. With the longer spokes, it will turn over at least 30 times with a good spin by hand (and air plug removed). (Again, trying to figure out video...)
D. Too much heat getting to the power piston. I added 0.4mm gaskets under both pistons and the base plate, and a 1mm gasket between the displacer cylinder and (under) the base plate. The base plate is 12mm thick Aluminium, which can hold a lot of heat, while the de Waal plans called for a 4mm thick piece. I really hope this is not the problem because replacing the base plate will not be easy...and will mess with the overall design since the shaft for the flywheel assembly bolts into both the baseplate and the top plate (also 12mm Alu).
E. Not enough air getting to the top of the power piston. In the original plans, the top of the power piston is open. I added the brass top with the small slit cut in for the power piston rod (photo 2) since I thought it would look better. I can,t imagine why this could cause a problem, but....what do I know?
F. Dead space in the displacer cylinder. Yeah, there is a out 8-9 mm of dead space, the result of my modifications from the plans. I made the displacer piston relatively early, and it is a bit short.
G, Demons. The machine is simply possessed and I need the services of a wizard to exorcise the evil that lives inside it.
Any thoughts on this project would be greatly appreciated!
Q: Are there any guidelines on “balance”? For example, should the counterweights on the crankshaft be heavy enough so that, when at rest, the displacer piston is actually raised (ie pulled up by the weight of the counterweights)? In the other vertical Stirling I built (link above and pic 6 below), the displacer is still heavier than the counterweight, so at rest the displacer is at its lowest position.
Q: the plans in the kyko have the same diameter for both the displacer and the power piston cylinders. The moriya fan does not. Is this a problem for the kyko? Most other plans I’ve seen for vertical Stirling have smaller diameter power pistons.
Q: To address the dead space in the displacer piston (point F above), I am thinking about making the crankshaft arms longer. Plans call for a 28mm travel for the power piston, and a 38mm travel for the displacer. What if this were 28mm power piston travel and 46mm displacer piston travel? This would solve the dead space problem, but I’m not sure if the travel distances should be that different.
Thanks in advance for your time!
PMM
