I did indeed have the Pro Drive cog belt system, but in all fairness the factory stock chain drive had secondary shaft failures as well. I witnessed one of these failures when I was at the factory for flight training. And the chain drive imparted much less bending moment on the shaft than the cog belt did/does.
Running a cog belt loose is the not the answer either. I used this logic early in my flying career, and my shaft still failed. If it is too loose, the teeth of the belt can ride up on the teeth of the sprocket imparting instantaneous catastrophic tension/stresses. Finding the "happy spot" that keeps the cog belt from tightening too much due to sprocket expansion, and running it too loose is very elusive.
You should check out the EPI engineering web site. I persuaded Jack Kane to look into this issue after my secondary shaft failure. He did exhaustive finite element and stress analysis of this issue and other issues on this helicopter. He is active in the Reno Air Race community, and designs power plants and PSRU's (propeller Speed Reduction units). Link below:
http://www.epi-eng.com/
Many builders have been putting Solar T62 turbine engines in Rotorway helicopters for years, and I think that's the stock engine they use in the Helicycle. Do a Google search on Jet Exec and Helicycle.
Be advised, BJ schramm the developer of the Rotorway helicopter and more recently the Helicycle spent his lifetime designing and building helicopters. He ultimately died in one of them. If you're objective is to design and build that is one thing, but if you're doing this as an inexpensive way to get into flying helicopters, you're better off just buying one.
Running a cog belt loose is the not the answer either. I used this logic early in my flying career, and my shaft still failed. If it is too loose, the teeth of the belt can ride up on the teeth of the sprocket imparting instantaneous catastrophic tension/stresses. Finding the "happy spot" that keeps the cog belt from tightening too much due to sprocket expansion, and running it too loose is very elusive.
You should check out the EPI engineering web site. I persuaded Jack Kane to look into this issue after my secondary shaft failure. He did exhaustive finite element and stress analysis of this issue and other issues on this helicopter. He is active in the Reno Air Race community, and designs power plants and PSRU's (propeller Speed Reduction units). Link below:
http://www.epi-eng.com/
Many builders have been putting Solar T62 turbine engines in Rotorway helicopters for years, and I think that's the stock engine they use in the Helicycle. Do a Google search on Jet Exec and Helicycle.
Be advised, BJ schramm the developer of the Rotorway helicopter and more recently the Helicycle spent his lifetime designing and building helicopters. He ultimately died in one of them. If you're objective is to design and build that is one thing, but if you're doing this as an inexpensive way to get into flying helicopters, you're better off just buying one.