|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

04-26-2011, 11:36 AM
|
 |
|
|
Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
|
|
Quote:
Originally Posted by DeltaRomeo
Question #2: What MP/RPM (not leaning) settings gets others the highest MPG?
|
The RV is VERY linear in speed and fuel flow. Its not a bell curve.
What that means is that there really is no best mpg. The ratio of FF to speed is pretty constant.
__________________
Kahuna
6A, S8 ,
Gold Hill, NC25
|

04-26-2011, 11:49 AM
|
|
|
|
Join Date: Oct 2007
Location: Sherrills Ford, NC (Lake norman area)
Posts: 432
|
|
MPG in GRT
Mike look at the very bottom of page 5.3 in the setup guide. Looks like it is called performance/fuel box 2. You can select MPG there.
|

04-26-2011, 12:24 PM
|
|
unqualified unfluencer
|
|
Join Date: Jan 2005
Location: Highland Village, TX
Posts: 4,088
|
|
4_26_11 PIREP: 27.7mpg
.3hr lunch flight. Just in the door.
OAT 58°F. 1,300 MSL.
15.6" MP 2290 RPM 4.9 gph fuel flow
118.5 kts IAS (TAS and GS within 1kt of each other)
124 kts ground speed. Agressively leaned.
Hottest CHT 335°F. Hottest EGT 1410°F.
14kt wind from 90 degrees right. Autopilot on holding altitude and heading.
Image below photoshoped to get screens closer together.
27.7 MPG was the best I could get varying MP and RPM. Fun to play with.
Over $130 to fill up my RV last time.....I might be doing the 'Best ECO' settings a lot more in the future!
__________________
Doug Reeves (your host) - Full time: VansAirForce.net since '07 (started it in '96).
- Part time: Supporting Crew Member CAE Embraer Phenom 300 (E55P) @ KDFW.
- Occasionally: Contract pilot (resume).
Last edited by DeltaRomeo : 04-26-2011 at 06:58 PM.
|

04-26-2011, 01:30 PM
|
 |
|
|
Join Date: Sep 2006
Location: Townsend, Montana
Posts: 3,179
|
|
Nice bunch of numbers, really shows the ability to conserve if need be.
It also reminds me of something my Bonanza friend said when I ask him about fuel burn while running LOP: I didn't buy a fast airplane to fly it slow. 
__________________
Retired Dam guy. Life is good.
Brian, N155BKsold but bought back.
|

04-26-2011, 01:32 PM
|
 |
Senior Curmudgeon
|
|
Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
|
|
Quote:
Originally Posted by BillFear
Mike look at the very bottom of page 5.3 in the setup guide. Looks like it is called performance/fuel box 2. You can select MPG there.
|
Thanks Bill, I will try that-------it does state it is a "upper left" display box, but then it also says MPG 
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
|

04-26-2011, 01:41 PM
|
|
|
|
Join Date: Nov 2010
Location: Huntersville, NC
Posts: 138
|
|
If you have a tailwind, best MPG, or range, will be to pull the power back.
If you have a headwind, it's best to fly a higher power setting.
Some of you guys should try it and see what happens. I've really on heard about this, but have never actually seen the numbers.
Steve
|

04-26-2011, 01:47 PM
|
 |
|
|
Join Date: Jul 2005
Location: Detroit, MI
Posts: 1,587
|
|
How can this be?
Quote:
Originally Posted by Kahuna
The RV is VERY linear in speed and fuel flow. Its not a bell curve.
What that means is that there really is no best mpg. The ratio of FF to speed is pretty constant.
|
The drag curve is the same shape for RV's as any other GA aircraft (not laminar flow). Prop efficiency varies, but not a huge amount. Engine efficiency likewise. If you fly at your best L/D (for example, around 106-110 for a 6 or 7) you will get (no wind) best mpg. And if you fly at max velocity you will get poorer mpg.
I have never seen any evidence that an RV has a different shape drag curve than other airplanes. Do you have any?
This is an idealized illustration of the point, not specific to RV's. The green line for THP should be roughly proportional to fuel flow. Velocity is the x axis. It is not a bell curve but it is curved, not straight.

__________________
H. Evan's RV-7A N17HH 240+ hours
"We can lift ourselves out of ignorance, we can find ourselves as creatures of excellence and intelligence and skill. We can be free! We can learn to fly!" -J.L. Seagull
Paid $25.00 "dues" net of PayPal cost for 2015, 2016, 2017 and 2018 (December).
This airplane is for sale: see website. my website
|

04-26-2011, 01:49 PM
|
 |
|
|
Join Date: Dec 2004
Location: Gold Hill, NC25
Posts: 2,400
|
|
Quote:
Originally Posted by steve91t
If you have a tailwind, best MPG, or range, will be to pull the power back.
If you have a headwind, it's best to fly a higher power setting.
Some of you guys should try it and see what happens. I've really on heard about this, but have never actually seen the numbers.
Steve
|
huh?
Headwind and tail wind has nothing to do with the effeciency of the plane.
It also has no place in discussions of trying to determine power settings and MPG discussions.
Plotting your TAS against FF is the way to get it. It wont matter if your readings are accurate as long as they are relative to themselves.
We have a gazillion of these plots running around.
__________________
Kahuna
6A, S8 ,
Gold Hill, NC25
|

04-26-2011, 01:51 PM
|
 |
Forum Peruser
|
|
Join Date: Jan 2005
Location: Austinville, Alabama
Posts: 2,458
|
|
Quote:
Originally Posted by steve91t
If you have a tailwind, best MPG, or range, will be to pull the power back.
If you have a headwind, it's best to fly a higher power setting.
Some of you guys should try it and see what happens. I've really on heard about this, but have never actually seen the numbers.
Steve
|
Steve, I agree with you based on my non-RV experience. I'd like to see some real world data though.
P.S. to Mike. Slow down and think about this: We're talking about efficiency across the ground not efficiency through the air. The iPhone is slow right now so I'm out.
__________________
Don Hull
RV-7 Wings
KDCU Pryor Field
Pilots'n Paws Pilot
N79599/ADS-B In and Out...and I like it!
?Certainly, travel is more than the seeing of sights;
it is a change that goes on, deep and permanent, in the ideas of living." Miriam Beard
Last edited by rv7boy : 04-26-2011 at 02:00 PM.
Reason: Added ps
|

04-26-2011, 01:59 PM
|
 |
|
|
Join Date: Jul 2009
Location: Bonney Lake, WA
Posts: 295
|
|
Quote:
Originally Posted by Kahuna
huh?
Headwind and tail wind has nothing to do with the effeciency of the plane.
It also has no place in discussions of trying to determine power settings and MPG discussions.
Plotting your TAS against FF is the way to get it. It wont matter if your readings are accurate as long as they are relative to themselves.
We have a gazillion of these plots running around.
|
that is not quite correct. A plane's best efficiency over the ground is dependant on the relative headwind or tailwind. The higher the headwind, the plane needs to fly faster for best MPG.
__________________
Ryan Winslow
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 07:02 AM.
|