Need help on Soda Can beta engine

[sandy]

I am new to Sterling world...I am student of 14 yrs and am making a project for school with my team mates
I tried to follow the website instructions and made it only to see it doesn't start....lack of narration and missing details make it difficult
We followed all the instructions....
Appreciate if one of you seniors can help us fix our problem......
Our problem :
1. even when the power piston rod is not connected, the balloon does not expand when heated....is it not supposed to ?
So we guess the hot air is not reaching the elbow or not hot enough to expand the diaphragm ......possibility of leak ?
2. The diaphragm vertical cable does not rotate the crank freely.....so there seems to be friction
We will post a video of what we made if required......
This is the second time we made the engine but no luck......I am not sure whether the piston moves when the air below is heated......
Also the end of coolling stroke, the piston with steel wool sppear to close the elbow port to power piston......

[sandy]

We straightened the cable from diaphragm and other other cable, no luck...
1) still figuring out why the balloon does not expand when heated.............is it because the steel wool piston diameter is close to diameter of lower can ?
If we reduce the piston dia, will it help push hot gas move to top and expand the balloon ?
2) The instruction says when crank is at top, piston to be top of lower can.......but this blocks the opening to the elbow..............??
Shouldn't the displacer piston be lower than the elbow opening all the time ??
We really appreciate your quick support as our project is stuck !!! SOS .....
3) We could not find any animation or picture sequence to explain the principle of operation of the two cylinder soda can engine other than the animation with single cylinder ......this will help understand the operation of the real model and know the relative position of the displacer piston with respect to the opening to elbow.
Sandy

[Ian S C]

Sandy, Friction, you must get rid of as much as possible. Air leaks, is the plastic elbow completely sealed where it is connected to the displacer cylinder, and the diaphragm sealed to the elbow, it should move up and down without stretching (quite loose). I can't see what it is made of, a rubber glove, or a party balloon are good sources of thin rubber. Ian S C

[sandy]

Sir, the diaphragm is party balloon......I used double sided tape for sticking the elbow on the can........not sure how to check the diaphragm airleak......will try again.....

[sandy]

Checked for tightness of diaphragm, no luck :-(
Can you please answer my question on the position of displacer piston w.r.t elbow opening ?

[Ian S C]

I think the elbow is in the right place for this motor.
You would be better attaching the elbow with something like JB Weld, or epoxy glue.
Ian S C

[sandy]

Thanks. I did not suspect leak because the diaphragm never expands upon heating.......
I want to verify whether the balloon chamber receives hot air at all......how..
I wanted to know whether the position of displacer blocking the elbow when crank is at 6 O' clock is correct.......
This follows from the instruction that when crank is at 12 O Clock, displacer top is at top of the lower can.........

[Ian S C]

The crank on the diaphragm should be 90* from the other one ie displacer at 12 oclock, the diaphragm at 3 oclock.
One other place where there should be a minimal leak is where the displacer rod comes out of the cylinder. This rod should at the point of entry to the displacer cylinder be straight, and smooth, and pass through a tube of some sort that is a nice sliding fit.
You should be able to get rid of some of that wiggly wire that form the con rods. Ian S C