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Mnflyer
06-13-2008, 04:37 PM
Hi all, have a 2 blade 68" Warp Drive prop. installed on the HKS / Kitfox III it is an excellent combination in my book.

mclayton
10-17-2008, 04:06 AM
I have a question about the two blade prop on a two cylinder engine. First, some brief background. In a project I was responsible for, we had to measure the vibration spectrum on-board the aircraft we were using to mount an electro-optical sensor. We found that there were pretty strong components to the spectrum, corresponding to the rotation of the props, in this case, 4-bladed, at the engine RPM.

In the case of a two cylinder engine, you would expect to see a component in the spectrum at a frequency representing the piston movement for the two cylinders, but depending on the quality of the engine balancing, it would probably occur at a frequency equal the engine RPM. For a two blade prop, the vibration would also occur at the same frequency, if the prop was not in perfect balance. These two might re-enforce each other, resulting in an installation that is potentially noisy, and which has a lot of vibration. I have been told that this is the reason three bladed props are desirable (usually) for two cylinder engines.

Having said all of this, I have no data, and so don't know if the magnitude of the potential problem is severe, or not at all noticeable. Do you have any experience, based on your installation.

Mnflyer
10-18-2008, 09:16 AM
Hi Mike, well I don't know about all the tech information you are referring to but my engine runs a smooth with the two blade as it did with the three blade prop, although the 2 blade is somewhat louder but that is to be expected 2 blade props are inherently louder than 3 blade. The improvement in performance is such that the slight increase in noise is well worth it to me, actually it made the Kitfox sound more like my Champ in the plane and on the ground. I did install a Balance Master balancer behind the prop. And the prop is balanced to with in an ant's butt.:).
There is every kind and description of prop being used on the HKS, problay the most popular being the Power Fin then the Warp Drive and the GSC props, but there are 2 blade fixed pitch wood props, Kiev props and another variable pitch props from E Europe, and some IVO's.
I tried an IVO on my Kitfox and did not like it at all there was increased vibration and I experienced CHT increase to red line in less than 40 min. of flt time.

10/20/08
PS. after thinking about your post about vibrations and 2 cylinder engine are you talking 2 cylinder direct drive as with the 1/2 VW type engines? Most ground adjustable propeller mgf. do not advise using their props on direct drive engines. The HKS engine has a gearbox simular to Rotax engines.

mclayton
10-21-2008, 05:57 AM
Thanks for the info. It sounds like your installation is working very well. You referred to a prop balancer installed on your aircraft. I am not familiar with this. Is it something that you adjust on the ground, or does it work automatically during operation of the engine?

Thanks again!

Mnflyer
10-21-2008, 08:00 AM
Hi Mike the Balance master balancer is automatic it can be purchased at a number of suppliers Leading Edge Airfoils for one. That's were I got mine that I bought for the 582 to try with an IVO 2 blade but I didn't like the IVO so never really used it till I installed the 2 blade Warp Drive prop.
Here's a link to the mfg.: http://www.balancemasters.com/