I was thinking about this....may be I mean to say that at a given
manifold pressure (19.0 in my case), 2250 RPM, 10 gal and 12,500 (65%
as stated in lycoming HP chart) I will lose speed if I increase RPM
and keep everything else, including fuel, constant.
Now guys, don't jump all over me for being wishy-washy!
Rene, you should always be able to go faster at a higher altitude!
Right?
At the end, I believe that we are very close to each other since it is
hard to make a major rigging error on the 10. We are just measuring
with different instruments and comparing speeds at different parameters.
I have enclose two photos of my panel from a trip. They are both
taken on the same trip at different altitudes. I have done the GRT
speed correction but will try the GPS speed calibration for the next
one. Now, if my outside temp sensor is really out of wack and my
numbers are off, it is not my fault!
I took these shots with the AP engaged and the plane level in smooth
air, with everything settled. Notice no vertical speed, TAS on the
right bottom and OAT.
You might think that I am a real liar, but if I wiggle my rudder just
right, I get a couple of more knots.
On Sep 3, 2008, at 7:04 PM, Rene Felker wrote:
>
> 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:
>
>> <wcurtis@nerv10.com>
>>
>> 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)
>>
>>
>>
>>
>>
>>
>>
>>
>
>
