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  #31  
Old 10-31-2020, 05:54 PM
Martyrv6a Martyrv6a is offline
 
Join Date: Jan 2005
Posts: 105
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Talk about a fat boy, my RV-6A empty weight was 1134 pounds! I followed the plans meticulously and did remove all the lightning holes in the ribs. I have a painted interior, and DJ seats from Cleveland tool, Lyc 0360 and Hartzell CS prop.. I did put a new panel in it with a G3X and GTN 650 but what I took out weighed at least that much so I might’ve dropped a few pounds. My gross weight Is 1875 pounds. I have flown it at Max gross weight but you do need to watch the fuel burn as the CG moves aft. In this condition I never fly below 10 gallons in the tank and it gets very light on the tail. This allows me to carry a pilot and passenger each weighing 200 pounds, 100 pounds in the baggage compartment and full fuel and never get outside the CG envelope. I guess my weight problem must be all that pretty paint! If I fly aerobatics I make sure to keep it light as possible, which means I start out with 15 gallons of fuel and just me. Marty N826ME
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  #32  
Old 10-31-2020, 07:49 PM
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plehrke plehrke is offline
 
Join Date: Sep 2006
Location: Defiance, MO
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Quote:
Originally Posted by Latech15 View Post
I’ll take the trade off of the comfort and situational awareness for carrying capacity all day long.

I’ve also done stalls and slow flight at that weight and had no issue with the cg.
Weight effects more than just stalls and CG position. Although situational awareness may bring you some safety in some situations, flying heavy eats away your safety margins every time you fly heavy.
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RV-6A - flying 14+ years, 950+ hours
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  #33  
Old 10-31-2020, 09:41 PM
FireMedic_2009 FireMedic_2009 is offline
 
Join Date: Nov 2016
Location: Tampa, FL
Posts: 175
Default 1112 lbs

My IO-320 6A with fix pitch was 1112 lbs after I installed one 10" display, G5, GTN650, Sorcerer, GMA240, GTX327 and cloth seats (no other interior) and regular battery, PC680. I did have a backup alternator. I re-painted the plane which was stripped to the aluminum, primed and painted with single stage paint. I know the lower cowl was heavy because I had to re-glass the exhaust exit along with other areas, let's say 8-10 lbs extra at most. I removed the aluminum around the windshield and roll bar and glassed it so maybe another 10 lbs extra maybe. I would think the majority of RV6's should be within 40-50 lbs of each other. The scales I used were car scales which were not certified so not sure how much they were off if any.

I'm not sure how one plane can weigh 1030 lbs and another weigh 1160 lbs even if one plane is just cloth seats with basic VFR with light weight prop and another plane fully decked out interior and CS prop. A 130 lbs difference is quite a range difference. Your big hitters on weight and this is just an estimate is prop (CS metal vs fp carbon fiber) 25 lbs difference, a/c battery 10 lbs difference, paint vs no paint 25 lbs difference, basic interior vs decked out, 25 lbs difference, poor fiberglass work 20 lbs difference. This is 105 lbs from one extreme to the other.

Are these estimates about right??? I'm curious how many of the 6's weighing < 1050 lbs have no paint, light wt props, and some other extreme weight saver?
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  #34  
Old 11-01-2020, 08:22 AM
Latech15 Latech15 is offline
 
Join Date: Apr 2018
Location: louisiana
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Quote:
Originally Posted by plehrke View Post
Weight effects more than just stalls and CG position. Although situational awareness may bring you some safety in some situations, flying heavy eats away your safety margins every time you fly heavy.
Please elaborate....
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  #35  
Old 11-01-2020, 08:30 AM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
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Quote:
Originally Posted by Latech15 View Post
Please elaborate....
Increased stall speed, reduced climb rate, lower structural margins, increased wear and tear.
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  #36  
Old 11-01-2020, 11:16 AM
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Sam Buchanan Sam Buchanan is offline
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Join Date: Dec 2004
Location: North Alabama
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Quote:
Originally Posted by Kyle Boatright View Post
Increased stall speed, reduced climb rate, lower structural margins, increased wear and tear.
And as the CG moves back to the aft limit (or beyond it??) pitch stability disappears. Instead of the stick returning to neutral pitch after disrupting it, it will remain in the deflected position. This increases workload and can be dangerous for an inattentive or inexperienced pilot.

I experienced this in the RV-6 very early on the first long cross-county trip when I loaded the baggage compartment more than I realized and carried a hefty passenger. I asked Mike Seager about this when he was flying the RV-6 around the country with a heavy load while doing transition training and he told me that with an aft CG "you have to fly the plane all the time". I found this to be very true and learned from it, and never loaded the -6 that way again.
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Last edited by Sam Buchanan : 11-01-2020 at 11:18 AM.
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  #37  
Old 11-01-2020, 05:24 PM
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plehrke plehrke is offline
 
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Location: Defiance, MO
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Quote:
Originally Posted by Latech15 View Post
Please elaborate....
The RVs have been designed, analyzed, and tested to a given weight. Any time you are flying at a weight higher than the designed to weight, you are cutting into the safety margins. How much are you cutting into the safety margin you do not know unless you did the analysis that says what part fails at what loading doing what maneuver. Flying my RV-6A at 1650 lbs I know I have a 1.5 times safety factor. Flying at 1700 or 1800 lbs I have no idea what my safety factor is and what part may fail at what load factor. Structural behavior in aircaft under flight and ground loads is not linear so assuming you are only a few percent over the loading does not mean you are only giving a few percent of the margin.

Remember, above the design to loads there is a safety factor that parts are not supposed to fail until 150% of that load. What people never realize is that any loading above design to load up to failure, permanent structural deformation can occur.

Will the airplane fall out of the sky if you fly at 1800 lbs, probably not. Could you get some structural deformation if you hit a gust that bounces you at 3 gs, or you land hard at 1700 lbs, yes. It may not break but then next time you fly heavy and hit that same gust or land hard your airplane is a little weaker and no longer has the same safety factor and could fail. Safety Margins are there for the unknowns of the design, analysis, build, and test and not to be used to increase operating envelops with out new analysis and test.
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RV-6A - flying 14+ years, 950+ hours
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Paid dues yearly since 2007

Last edited by plehrke : 11-01-2020 at 05:28 PM.
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  #38  
Old 11-02-2020, 10:35 AM
Robert Sailor Robert Sailor is offline
 
Join Date: Nov 2018
Location: Nanaimo BC Canada
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Our aircraft is a 6A and the builder registered an 1800 lb gross weight. It has the IO-320 and CS prop and the battery is mounted on the firewall. Empty weight is very close to 1100 lbs.
The critical formula is the CofG and insuring thatís itís kept inside the range, especially with empty tanks.
Lots of discussion on weights over the original weights specified by the designer.
Obviously itís prudent to stay within the original weights however there maybe some comfort in knowing that the RV 6 was built in the largest numbers plus the greatest total time of flying hours and to date, if Iím to believe whatís been published ....there have been no structural In flight failures. Considering that these aircraft have engaged in aerobatics 2 up on an ongoing basis, well over the suggested gross weight and Iím sure by less that well trained pilots It does suggest that there just may be a bigger cushion of strength than we think. Again, Iím not promoting flying over gross or doing aerobatics over the suggested gross weights, all Iím saying is that many pilots are doing it and so far, over many years and thousands of flight hours the structure seems to be able to take it.
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  #39  
Old 11-02-2020, 02:55 PM
bill.hutchison bill.hutchison is offline
 
Join Date: May 2020
Location: Northern VA
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This is certainly an interesting topic.

I took my empty weight and CG information and ran through a bunch of loading scenarios at 1800 pounds and I never got out of CG all the way down to 8 gallons even with me, normal-sized pax and 100 pounds of baggage.

That being said, I've been treating it as a 1650-max-gross airplane until I get the rest of my mods decided on. Then I'll have everything re-weighed.
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  #40  
Old 11-02-2020, 05:32 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by Robert Sailor View Post
The critical formula is the CofG and insuring thatís itís kept inside the range, especially with empty tanks.
There are numerous critical considerations.

Loads carried by landing gear, in flight gust loads, and a reduction in limit load would be just a few others.
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RV-6A (aka "Junkyard Special ")
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