Boll aero 18 internet drawings

Hi Geoff, It is all looking good ,so you are not far off hearing its first cry!

Keith

Yes looking good Geoff hope you've got plenty of fuel

I agree with Keith that unless you are going to use it in anger so to speak a comp screw lock is not essential but handy if the engine does show a tendency to back off compression whilst running.

Vibration is usually the cause but a less than ideal fit on the contra piston doesn't help either. A small mod that helps is to drill the end of the comp screw to give a circular land rather than a potential point contact. Doesn't have to be deep just deep enough.

Good luck with the final phase

Best - Tug

Hi Thanks again Gents,

More progress reports in due course.

I need to make another fixture to hold the piston while lapping into the cylinder, like this one I used on the firefly.

Cheers for now

Geoff

Regarding the crankshaft of the BollAero 1.8cc, my original had the prop driver screwed onto the shaft, this was the same as the ML Midge which inspired my engine design.

The small Sparey diesel also used this method. Ron Chernich drew the other alternative versions.

My aim was simplicity above all, the engine was originally published in Aviation Modeller magazine, which was not read by experienced model engineers, in general.

Ron also swapped sides of the exhaust and intake from my original, I prefer my original way for upright installation in a plane.

All my engine plans are now on the Outerzone website, with the magazine articles for the AMI 1.8 and 4.4cc.

The 7.5cc diesel is not included as I haven't got around to doing an assembly drawing, but three engines have been built from the component drawings and run well.

I have been very pleased that the 1.8cc has been made in many countries including Finland, Mexico and Argentina and all of these can be seen on YouTube

Hi All and Chris, thanks for your post,

Well all assembled and ready I believe for a test run.

The engine is made much the same as the original design. I split the crankcase in two and modified the prop shaft to accept a commercial prop driver but other than that made to Ron's drawings and Chris Bolls design..

The compression feels good and all seems as it should be? (hopefully).

Will be travelling to Chester soon to see my mate who is an aero modeller. If this engine will start he will get it going!

So fingers crossed and if all's well a video to come.

Ramon you asked if I had plenty of fuel to run the engine. The answer is no but as you may have gathered I know a man who has!!

atb Geoff

Very nice result Geoff so I hope you have even more success with it running - nothing beats that huge grin that breaks out when an engine you've made breaks into it's first run

Best - Tug