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  #11  
Old 09-27-2018, 07:02 PM
Christopher Murphy Christopher Murphy is offline
 
Join Date: Feb 2007
Location: colorado
Posts: 783
Default Do you understand?

Quote:
Originally Posted by phi75 View Post
Ok thanks
2 weeks ago I do a flight with 115 lbs rear pax we lbs baggageís full fuel ans was ok
But never try with more .
People are telling you that the less fuel you have the farther aft the cg is?

With a very aft cg the airplane becomes much more difficult and demanding to fly. If you arent a stick and rudder person you might get into trouble.

Its not the weight. Its the cg
Cm
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  #12  
Old 09-28-2018, 11:01 PM
SJordan SJordan is offline
 
Join Date: Sep 2016
Location: Scottsdale, AZ
Posts: 169
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Just took my first passenger (wife) up last night in our new -4. From reading this post I was very nervous about the landing! After two landings last night I think I can call a back passenger sub 130lb a non event in my -4. It was pitch sensitive for sure on landing as you can see in this video but the second landing was much better. Not sure though I'm willing to try any 200lb guys anytime soon though.

https://youtu.be/PNttme3aBx0
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  #13  
Old 09-29-2018, 02:31 AM
seward747 seward747 is offline
 
Join Date: Jan 2005
Posts: 138
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Sean: nice video, beautiful -4!
Thanks for sharing.

Doug
Seattle area
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  #14  
Old 09-29-2018, 09:32 AM
mbert mbert is offline
 
Join Date: Oct 2017
Location: Altus, OK
Posts: 9
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Shawn cool video! What mounts are you using on the wing tips/tail for the cameras?

Myles
RV-4
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  #15  
Old 09-29-2018, 07:59 PM
Tankerpilot75 Tankerpilot75 is offline
 
Join Date: Jan 2015
Location: Oklahoma City, OK
Posts: 326
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Just remember - if you find yourself with an unexpected aft cg; forward (nose down) trim is your friend. It helps keep you from over controlling the aircraft due to increased pitch sensitivity.
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  #16  
Old 09-29-2018, 08:16 PM
Dean Pichon Dean Pichon is offline
 
Join Date: May 2006
Posts: 466
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Quote:
Originally Posted by mbert View Post
Shawn cool video! What mounts are you using on the wing tips/tail for the cameras?

Myles
RV-4
Same goes for me. Beautiful -4 and great video. Please share details of your cameras and mounts. Any noticeable impact to aerodynamics?

Thanks,

Dean
Bolton, MA
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  #17  
Old 10-11-2018, 09:15 PM
Whitman Whitman is offline
 
Join Date: Oct 2010
Location: FL
Posts: 211
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Quote:
Originally Posted by Christopher Murphy View Post
People are telling you that the less fuel you have the farther aft the cg is?

Cm
Thatís true in the rv4 and many other rvís. Do you disagree? While running the CG in foreflight Iíve noticed that I can be in limits for takeoff but approaching aft limit for landing and will sometimes get a zero fuel CG caution.
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  #18  
Old 10-12-2018, 07:42 AM
Nate-ISU Nate-ISU is offline
 
Join Date: Mar 2013
Location: Indianapolis
Posts: 44
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Fuel is forward of the spar. I'm not going to use absolutes and say this is the case with every -4, but in mine and others I've spoken with, additional fuel (weight) moves CG forward. To put another way, CG moves aft as fuel burns.

W&B with the -4 is a game; for me it's a question of: "Do I want to be in CG and over weight? Or aft and under gross?" I'll pick CG every time. No more than 200lb's behind my rollbar; 0-320 w/wood prop. I've flown the plane with the CG just aft of limits; its controllable (IN MY PLANE) but simply sucks the joy out of flying her entirely. Even a 120lb passenger, while better, changes the handling dynamics enough that I just prefer to fly solo, and doubly so if there's going to be anything more than an aileron roll.
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  #19  
Old 10-14-2018, 07:56 AM
Whitman Whitman is offline
 
Join Date: Oct 2010
Location: FL
Posts: 211
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Quote:
Originally Posted by Nate-ISU View Post
Fuel is forward of the spar. I'm not going to use absolutes and say this is the case with every -4, but in mine and others I've spoken with, additional fuel (weight) moves CG forward. To put another way, CG moves aft as fuel burns.
Youíre correct. Nate appeared to be questioning our logic as if it was flawed. Iíd be surprised if any RVír can get their CG (with flyable weights) to be in the very forward limit where your logic is incorrect. CG does in fact move aft as fuel burns.

Rv-4 CG range
68.7-77.4

Fuel tanks are 70 inch aft of datum

RV-7 CG range
78.7-86.82

Fuel tanks are 80.0 inch aft of datum
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  #20  
Old 10-14-2018, 11:03 AM
Christopher Murphy Christopher Murphy is offline
 
Join Date: Feb 2007
Location: colorado
Posts: 783
Default Maybe I wasnt clear

Quote:
Originally Posted by Whitman View Post
Thatís true in the rv4 and many other rvís. Do you disagree? While running the CG in foreflight Iíve noticed that I can be in limits for takeoff but approaching aft limit for landing and will sometimes get a zero fuel CG caution.
I was getting the impression the OP was under the impression that he could. Carry more weight in the back seat by reducing fuel. I was trying to explain that its not the weight as much as the CG with the RV4

Cm
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Pitts S1S "Mexican Red" sold and missed
Mr. Twister Airshows
Rocky Mountain Renegades
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