Constant speed newbie questions
 

Greetings all. This past weekend I converted my RV-9A from a Catto 3 blade prop to a Whirlwind 200RV. Since this is my first constant speed prop I have a lot of learning to do and one of the things that I need some help with is glide ratio.

With my Catto if I pulled the power my glide ratio was about 12:1. When I pull the power on the WW200RV my airplane feels like its practically dropping out of the air. I doubt my glide ratio is much more than 6:1 (not measured, guestimate). I know the prop is designed to go to the high speed stop on a loss of engine oil pressure. If thats the case my glide options just became seriously limited. Am I missing something?

I know this will generate a few opinions and a few questions so for those of you who are going to ask things like "why did you do that" or "what are the pro's and con's" I posted some of my thoughts to my blog. http://www.darinanderson.com/2017/07...ant-speed.html

I don't know anything about the Whirlwind prop, but....

The typical mode of operation, with a CS speed prop on a single engine aircraft, is for the blades to go to full fine pitch if you lose oil pressure (twins go to feather position). This exposed the most surface area and may feel like you just hit the airbrakes.

If you were to pull power and pull the prop lever back to full coarse pitch, you should see a significant improvement in glide. In a real engine out scenario, you may not have the hydraulic pressure to do that though.

Don't think you are missing anything except the magnitude of the change in glide ratio seems a bit severe. I expect you will test it to confirm.

On my Rocket I get between 2 and 3 difference, eg: from 6.8 to 9.2, when I pull the the prop back while testing the glide ratio. Of course as already mentioned, if you lose oil pressure the option of pulling the prop lever back won't do anything for you.

An aerobatic prop will go to coarse pitch when oil pressure is lost.