REFLECTOR: Performance Question

[Scott Derrick]

Its interesting how performance numbers never coincide like you would 
think they should. Either our engines are all producing much different 
power when comparing 200HP IO360's or the props are truly different(my 
choice).

My engine is a 200HP IO360 with a Catto 64x74

I get between 2300 and 2400 static depending on altitude and temp. I 
cruise at 170+ KTAS at 2700 RPM, burning about 9-9.5 GPH.

Ronnie said with his 200 HP IO360 and Catto 66x72
Got 2160 static and cruised at 165 knots.  The cruise is close to mine 
the static is completely different.
Ronnie said his new Catto 66x70 prop had a static of 2400 and cruise of 
165 at 2700RPM.

Odd huh?  I realize Ron's prop is 66" long, mine is 64", which is 
probably whats making the difference the difference, but what a 
difference with 2"!

Scott


Ron Brown wrote:

> Dave,
>
> I am flying off of Lake Norman Airpark (14A) which is 3000' and 840' 
> MSL with trees on both ends.  I have a 173 RG, 200 hp with a Craig 
> Catto 66x70" prop.  3000' is fine if not heavily loaded and hot.  I 
> can take off comfortably with 2 on board with luggage (or 500-600 lbs 
> of people) and 20 gallons of fuel on a cool morning or cool day.  If 
> its 90 degrees outside, then the limit is 300 lbs and 20 gallons.  I 
> wouldn't be comfortable with less than 3000'
>
> I would highly recommend doing your test flights from at least 5000' 
> runways and then work on your short field techniques and determine 
> what you are comfortable with.
>
> My friend Jim White had the same plane you have.  It used perhaps 500' 
> more runway than mine, but he had more pitch in his prop (66x75?).
>
> By the way, re the high DA discussions and fixed pitch props:  I first 
> started flying with a 66x72" prop.  My maximum cruise was 165 knots at 
> 2550 rpm but take off was anemic with a static RPM of only 2160 rpms.  
> I had Craig repitch the prop to 66x70", take off was much improved 
> with 2400 rpm static, and max cruise is the same - 165 knots but at 
> 2700 rpm (it could go higher, I pull back on the throttle as it 
> reaches 2700 rpm).
>
> Sounds like you are getting really close to flying soon!!!
>
> Ronnie
>
>
> ----- Original Message ----- From: "Dave Black" <dvblack at comcast.net>
> To: ".Velocity Reflector" <reflector at awpi.com>
> Sent: Saturday, February 05, 2005 11:47 PM
> Subject: REFLECTOR: Performance Question
>
>
>> I have a shortwing RG / 200hp / Performance Prop. One month to 
>> completion and holding.
>> How much runway will I need once the airplane and I become familiar 
>> with each
>> other?
>> Is 4000 ft adequate?
>> What about 3000 ft?
>>
>> Dave Black
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