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August 12th 2015

A project log for Advanced Stirling Radioisotope Generator

NASA cancelled this program in 2013 after spending USD260 Million. Lets see what we can do for USD260!.

MW MotorsMW Motors 08/12/2015 at 12:270 Comments

The project to date is very poorly described. We have been working to fabricate the parts. For such an apparently simple device, fabrication has been very difficult. Parts can be seen in the video below.

There is a strong metal ring. You can see that this has 3 springs attached. These 3 springs sit on a frame. The frame is visible at about the 30 second point in the video. At about the 4 second point, you can see we also have a regulator attached to the big structural ring.

You can see the hot cap & this is screwed to the ring with 12 screws.

On the reverse side, there are 24 screws holding the beryllium copper membrane in place (sourcing Beryllium copper is hard, we found some at a very specialist UK online shop). Forming the Beryllium copper to the correct shape is even harder but that is for a different project log.

At about 35 secs, we have removed the 12 screws so we can take away the hot cap (outer Can). We can now see the displacer (inner can). The outer can has a metal ring & a seal to keep it in place & to keep the device air tight.

At 52 secs, when we remove the displacer, you can see the planar spring. This is screwed to the top of the displacer by 3 screws. For the device to function, the planar spring must be completely straight. Our spring is not straight, hence the device does not work. Forming a planar spring is far from easy. Using any normal methods, the spring will warp. We now know that the only realistic way to make a straight spring is to use a water cutter. Thankfully, we know someone who has one of these so a new spring is on the way.

When heat is added to the hot cap, the displacer acts on the planar spring. The spring acts on the 'chamber". You can see slight movement on the chamber at about 1 min 30 secs (before we remove it as at this time we have already removed the 24 screws from the other side.). Movement of the sealed chamber is critical !.

At about 2 mins, you see inside the displacer. The component inside ensures that the displacer does not lose its shape when heat is applied to the outer can..

At 3 minutes, we are trying to show the 'free movement' of the displacer inside the outer can. Obviously, we do not have free movement. Without free movement, the device will not work... The gap between the displacer & outer Can is supposed to be as small as possible (like 1mm) but still allow free movement. We are going to rework the inner & outer cans to get the required free movement.. Honestly, even making the inner & outer Cans to this degree of accuracy is challenging. The gap has to be uniform. We do not know any easy way to make these things. We just got some metal & bent is as best we could. To add to the complexity, the bottom of each Can needs to be slightly curved as the device will not work with a flat bottom.. The curves on both have to be the same.. It is just a matter of fiddling around with the metal, cutting it accurately & welding it. But expect to have a good few goes before you get it even half right.

At about 5 minutes, we remove the sealed chamber containing the beryllium copper membrane. You can also see a rubber gasket. At 5.40 the basic idea is that the planar spring should touch the sealed chamber. This does not happen for us because the spring is warped. The sealed chamber has divots for the screw tops as the spring, not the screw tops should act on the chamber..

The sealed chamber holding the inner part of the membrane is sealed using a single central screw. Both sides of the sealed chamber have rubber gaskets (it is hard to see these in this video)..

What is visible in this video is only half the device. On top of this, we need to place a magnet & coil contraption. The magnet & coil will turn the motion into electricity. The 'motion' in this device is movement of possibly 1mm. We will be able to detect the motion when we get it working & the magnet assy being attached or not should not effect functionality of this half of the device..

So, there we have it. A badly described device that does not work !. But, if we can make it work, it will be an amazingly elegant electricity generating device. It should work from any heat source. This leads to the tantalizing possibility of running it on solar power during the day & gas at night. That would be a biggie, meaning that a solar device does not have to do noting when the sun does not shine... & even NASA could use solar power when their plutonium runs out in deep space..

“Course heading, Captain?”. “…Second star to the right — and straight on 'til morning.”

More updates to follow....

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