REFLECTOR: Engines and High DA

[Jim Sower]

Kurt,
With over 300 hp, wouldn't you be in a position to sort of brutalize the 
high DA issue, even with a fixed pitch cruise prop?  Like you say, the 
airplane is going to unstick at some speed, and even if you're pretty 
badly stalled at brake release, you will tend to make up for it when you 
do pick up some speed.  I would tend to think that with power like that, 
you'd be OK even at 10,000' DA.  You might not leap off in 2500', but 
there's not many 2500' runways in that part of the country to where 
you'd need to.

I'm just leery of the cost-benefit and overall performance of CS props 
... Jim S.

NMFlyer1 at aol.com wrote:

>Al, 
>
>I agree that one of the best ways to reduce takeooff roll is to get a variable pitched prop. That way you can try and get the engine wound up to its highest rated rpm (or closer than you can with a cruise prop) and obtain maximum HP. 
>
>My own logic was that the Velocity will rotate at a given speed. We all know it just rolls down the runway for a comparatively LONG time to get to that speed. So, lets get to that speed as fast as possible!! The longevitity, reliability, and long term cost basis add in there as well for my choice. 
>
>So, in my application (to battle the high DA here) I have decided to increase HP AND use the constant speed prop.  The Chevy has been dynoed to 340 HP (although I probably won't run it harder than 325 @ 5000rpm max takeoff). 
>The variable pitch prop should allow me to spool up to max HP, but also allow me to use the huge ammount torque I have at cruise speeds. 
>
>It is going to take some flying to figure out the sweet spot between best engine power and best prop pitch. That just adds to the fun.  
>
>good write up on engine choices too Al, Always appreciate your input. 
>
>Kurt Winker
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