Boy, I really feel slow now......
12,500
12.2 GPH Rich of peak
2480 RPM
161 knots (TAS from GRT)
My speed test at 8000 feet and 75% power showed about 171......but I have
not seen speeds like that in cruise at 12500.
Rene' Felker
RV-10 N423CF Flying
801-721-6080
-----Original Message-----
From: owner-rv10-list-server@matronics.com
[mailto:owner-rv10-list-server@matronics.com] On Behalf Of Rob Kermanj
Sent: Wednesday, September 03, 2008 4:28 PM
To: rv10-list@matronics.com
Subject: Re: Hartzell Composite Three blade RPM Test
I have been reporting best speeds at 2250 RPM. Perhaps with your
theory I can do better. I am curious and will test it and report back.
I consistently get 172 kts at 12,500 with 10 gal/hr burn. Perhaps I
really mean best speed/fuel economy combination and don't realize it.
I do know that being in absolute smooth air and giving the plane a
chance to accelerate for a few long minutes makes a big difference.
The speed goes all over the place with the slightest turbulence.
It will be a while before I can do the test but I WILL report back. I
also need to qualify that I do not have three blades so, who knows!
Thank for making me think.
On Sep 3, 2008, at 1:40 PM, William Curtis wrote:
>
> This is one of the reasons I shake my head when some report the best
> speeds at some low ~2200-2400 RPM. I discovered when I was breaking
> in a new engine on the Cardinal that my best power and speeds was at
> 2700 RPM. Anything less than 2700 would produce a slower speed.
> Now I primarily use two settings for my prop--2700 for takeoff, 2500
> for climb and cruise with occasional reduction during letdown.
>
> All things being equal, you will achieve the best power and speed
> from a prop at 2700 RPM. At 2700 RPM, and 50 degree ambient
> temperature, an 84" prop will have a tip speed of Mach 0.895. To
> produce maximum thrust at full power your tip speed should fall
> between .88 and .92 mach. The primary benefit of reducing RPM is
> for increased passenger comfort (less noise) and reduced engine wear
> an tear.
>
> What is the diameter of the Hartzell Composite Three blade?
>
> William
> http://nerv10.com/wcurtis/
>
> -------- Original Message --------
>> X-Rcpt-To: <wcurtis@nerv10.com>
>>
>> On my trip to Moses Lake and back over the weekend I tried different
>> propeller RPM's for speed. I was level at 8500 Ft and full
>> throttle. I started at
>> 2600 RPM and then tried 2500, 2400, 2300, and 2200; for every 100
>> RPM drop I
>> would see a couple of knots drop in airspeed.
>>
>> Rob Hickman
>> N402RH RV-10
>>
>>
>>
>> **************It's only a deal if it's where you want to go. Find
>> your travel
>> deal here.
>> (http://information.travel.aol.com/deals?ncid=aoltrv00050000000047)
>
>
