BollAero18 2021 Build

[Novian]

Here's a build log of a BollAero 18 I built over several months in Summer of 2021 and had my grandfather accompany to experience machining.

Unfortunately it doesn't turn over. Either the fuel mixture isn't correct or not enough compression.

First 10 Pictures of the Build:

Crank Case:


Cylinder:


Spray bar:


Main bearing Housing:

 

[Novian]

Cylinder Head:


Connecting Rod:

 

[Novian]

Piston and Contra-piston:


Piston and Connecting Rod Assembly:


Crank case, Cylinder, Piston, Connecting Rod Assembly


Further test assembly with unhardened crank shaft:


Crank Shaft Hardening Process O2 Drill Rod Quenching and Tempering:

Drill rod crankpin was later red loctite and pressed into crankshaft.

Mounted to block for test runs:


New, longer Venturi made to allow fuel tank to be attached to engine:

New spray bar made that threads onto fuel tank.

Final Assembly:

 

[Olli-Matti]

Thanks for sharing, it looks just fine, too bad it hasn' ran yet. Have you seen this article on making the piston fit to cylinder? If you are not familiar with this one I recommend to take a look and try it out!

AdriansModelAeroEngines.com :: Piston/cylinder finishing

 

[Ghosty]

A great looking engine, as above, piston fit is needed to be a very neat fit, the contra piston needs the same attention, except, it needs to be a tighter fit.
Hope you don't give up on it.
Cheers
Andrew

 

[f2cf1g]

Please don't run it on that prop, it may throw a blade which is extremely dangerous. It is made for electric motors and not designed to withstand the vibration inevitable in an i/c engine. Good luck in getting it running.

 

[Novian]

Please don't run it on that prop, it may throw a blade which is extremely dangerous. It is made for electric motors and not designed to withstand the vibration inevitable in an i/c engine. Good luck in getting it running.

Correct. It was just used for testing purposes and for the look, and what I had from my stash of RC airplane stuff. I will get a proper wooden prop meant for gas RC planes.

 

[Nibby2226]

When I made my Bol18 the piston / cylinder lapping took some hours. You want to achieve a very slightly tapered bore. I lapped until the piston "just" reached tdc. In fact the very last part off the process was achieved by hand without lapping paste but with plenty oil.
I built the Bol18 as a learning step for a Vega V twin. The piston/ cylinder fit is real gotcha on this "simple" engine. Keep the faith, it will run eventually....