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  #1  
Old 12-02-2017, 05:37 PM
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jsharkey jsharkey is offline
 
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Default Gross Weight Difference between 6 & 6A

Anyone know why the gross weights recommended for the 6 and 6A are different? The weights for the 7 and 7A are the same.

Also what is the limiting factor on the 6s that requires the lower gross weight? Is it structural or stability or something else driven?

Jim Sharkey
RV6 YO360-A1A 72/85 FP Sensenich
Flying since 2009
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  #2  
Old 12-02-2017, 07:09 PM
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Skid Skid is offline
 
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Default 6/6A Specs

Here is a link to the specs on the Vans Aircraft site.
http://www.vansaircraft.com/public/rv6specs.htm
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  #3  
Old 12-03-2017, 10:23 AM
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Originally Posted by Skid View Post
Here is a link to the specs on the Vans Aircraft site.
http://www.vansaircraft.com/public/rv6specs.htm
Thanks Skid

...wondered why the difference though?

Jim
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  #4  
Old 12-03-2017, 10:47 AM
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It's to carry the 50lb nosewheel...

I was told the limitation is the FAR 23 maximum landing load on the landing gear at gross weight. The nosegear + mains can carry just a hair more than the tail, so it gets a slightly higher gross. This is simpler than giving both aircraft the same 1650lb limit, and then quoting a maximum landing weight for the RV-6... Given there's no way to jettison extra load like in an airliner.
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  #5  
Old 12-03-2017, 02:55 PM
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Originally Posted by Snowflake View Post
It's to carry the 50lb nosewheel...

I was told the limitation is the FAR 23 maximum landing load on the landing gear at gross weight. The nosegear + mains can carry just a hair more than the tail, so it gets a slightly higher gross. This is simpler than giving both aircraft the same 1650lb limit, and then quoting a maximum landing weight for the RV-6... Given there's no way to jettison extra load like in an airliner.
Skeptical
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  #6  
Old 12-14-2017, 09:57 AM
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Quote:
Originally Posted by Snowflake View Post
It's to carry the 50lb nosewheel...

I was told the limitation is the FAR 23 maximum landing load on the landing gear at gross weight. The nosegear + mains can carry just a hair more than the tail, so it gets a slightly higher gross. This is simpler than giving both aircraft the same 1650lb limit, and then quoting a maximum landing weight for the RV-6... Given there's no way to jettison extra load like in an airliner.
Did Van's provide this to you directly or did it come from VAF / Internet? I'm curious because I was under the impression that the difference was due to the main gear weldments adding additional strength to the wing spar. Maybe it's both?
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  #7  
Old 12-15-2017, 10:18 AM
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Default Your mileage may vary...

Quote:
Originally Posted by ChiefPilot View Post
Did Van's provide this to you directly or did it come from VAF / Internet? I'm curious because I was under the impression that the difference was due to the main gear weldments adding additional strength to the wing spar. Maybe it's both?
When I was building the RV"X", (the combination of a 6 Fuselage and RV4 Wing/Tail) the GW subject arose several times. The X's fuselage was originally a 6A that I simply omitted the weldments and matched the RV4 wing to the 6 center section. The RV4 tail simply bolted right on, albeit 15% smaller surface area. The wings(RV4,6) BTW are identical. Their only difference is one rib bay of metal next to the fuselage. The spar box, minus the gear weldments is pure RV6 with an RV4 wing installed minus the one rib bay. This allows the RV4 to have longer ailerons, shortened flaps to match wingspan. Thus the X has a bit better roll rate with smaller flaps.

So, 6A gross weight, 6, 4? Van's eluded that the additional structure merits higher GW. However, "The X" is a one of a kind and Van's of course approaches the subject of modifying a design much akin to Area 51."Don't ask, don't tell". Being a former Rocket guy, I understood completely the term persona non grata!

I asked my AE friend "KK" what he thought about RV GW calculations once. His insightful words of wisdom concluded in my mind that GW calculations on EXP designs are well padded (by design). He added, "don't forget what is printed in 2" letters in plain view".
EXPERIMENTAL.

I used 1600# for a nice round number for the paperwork and it will carry every bit of it, and more.

V/R
Smokey

Last edited by smokyray : 12-15-2017 at 10:31 AM.
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  #8  
Old 12-15-2017, 10:39 AM
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Quote:
Originally Posted by smokyray View Post
...
[/i]
I used 1600# for a nice round number for the paperwork and it will carry every bit of it, and more.

V/R
Smokey
Isn't there a possibility that the "and more" bit could get you into trouble if an accident would happen. The FAA and your insurance company probably would not look well on an aircraft operating over gross weight.

I thought that is why most of the -6A's used a higher number on their official paperwork.
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  #9  
Old 12-15-2017, 06:48 PM
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Quote:
Originally Posted by ChiefPilot View Post
Did Van's provide this to you directly or did it come from VAF / Internet? I'm curious because I was under the impression that the difference was due to the main gear weldments adding additional strength to the wing spar. Maybe it's both?
It came to me years ago, so I cannot provide a source... It may even have been the Matronics list! I've taken it as gospel because it seems reasonable, but I admit I haven't looked into it in detail. My wife and I are on the smaller side so gross weight has never been an issue in our -6.
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