Finally we have an update - sorry for the delay.
We've been making a number of engine modifications and thought the best way to show them was with a talking picture book. The youtube video shows some of the latest engine modifications to date, following below is a short description of the significant modifications.
We're still in trial mode debugging and refining. To date the biggest design changes have been with respect to the displacer. The fin design of the displacer added too much weight to the reciprocating parts of the eninge. The displacer, after lighting weighed in at about 20 lbs. Think of a 20lb mass, reciprocating a 14" stroke,with a frequency of 240 cycles per min, just not going to happen for this design.
The new displacer is made out of closed cell foam and fiberglass board (hot end). The weight is down to about 9lbs and we think there is still a pound or two that we can get rid of from that on the next itteration.
In addition, we strengthened the input and output shafts with two more bearings which add a good deal of rigidity to the crank mechanism (in green).
We also added a second flywheel - ending up with about 40lbs in total flywheel weight With the expansion of the displacer, so grew the hot cylinder to accommodate its length of 40". The reason for lengthening the displacer was to improve the heat transfer for the movement of the working gas. None of the performance aspects of the engine change with this change in displacer length. Still the same amount of compression and same sweep volumes (close to the same).
In running our tests, we added some insulation to the fire box allowing up to reach 350C and higher if needed.
Currently we're working on the piston sealing - there seems to be too much friction with the configuration we are using today (3 delin rings). We are looking at alternative materials that will provide a similar seal with less friction costs.
Thanks for the continued support - Keep it coming ?
Working to get another update out shortly.