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Wt and Balance question

J

Jeff Bost

I'm New Here
Hi folks,

New member here. I 'm looking at a nice 6A for sale. The builder has won awards with this airplane and has excellent logs and documentation. In looking over the specs and limitations, he has the following numbers listed as max weights for the airplane:

Max weight normal category - 1850 lbs
Max weight utility category - 1703 lbs
Max weight aerobatic cat - 1375 lbs

Obviously Ive referenced this against Van's recommended GW of 1650 lbs. I'm looking for some guidance here as the empty weight is 1135. Not much useful there if I use 1650. If anyone is willing to discuss, please send me a PM and we can chat. Thanks for your help and best regards to all.

Jeff
 
The manufacturer/ builder of an aircraft determines the limitations.
However, Vans Aircraft has made calculations for their kit.
A normal category aircraft that is on a long range ferry flight can in most cases be overloaded 10 %. It requires a permit and nice weather the first hours of the flight. Yes, it will at a minimum affect stall speed and take of distance and the margin of structural integrity.
CATEGORY LIMIT LOAD
Normal [1] ------------------------------------- 3.8 -1.52
Utility (mild acrobatics, including spins) ----- 4.4 -1.76
Acrobatic --------------------------------------- 6.0 -3.0
If you reduce the Limit Load during over gross weight flight, the flight will
be safe. However the margin of safety is lower.
In bad weather it can bite back.

Good luck

https://www.vansaircraft.com/wp-content/uploads/2020/05/RV-6-6A-Manual-WB-Rev-3.pdf
 
Jeff:

Welcome to VAF.

I live and am based just a few miles north of you @ NC25.

Built my RV-6, first flight September 1997, have landed in 49-states, have over 3,500 hours on the hobbs, and was a DAR for 10-years before retiring / moving across the country.

I may not be the highest time RV-6 or RV-6 pilot but would not be afraid to bet that I am in the top 10% of the highest time.

If I cannot answer your RV questions, I more than likely know someone who can.
 
Thanks for the link to the wt and b manual. I’m a 23,000 hr pilot but all in certified aircraft. Experimental is a new venture for me. I’m hoping to speak with the builder and get some clarification on his thinking. Thanks again.

Jeff
 
RV6_flyer said:
Jeff:

Welcome to VAF.

I live and am based just a few miles north of you @ NC25.

Built my RV-6, first flight September 1997, have landed in 49-states, have over 3,500 hours on the hobbs, and was a DAR for 10-years before retiring / moving across the country.

I may not be the highest time RV-6 or RV-6 pilot but would not be afraid to bet that I am in the top 10% of the highest time.

If I cannot answer your RV questions, I more than likely know someone who can.
Click to expand...


Thank you sir. I sent you a PM. Jeff
 
Jeff Bost said:
Thanks for the link to the wt and b manual. I’m a 23,000 hr pilot but all in certified aircraft. Experimental is a new venture for me. I’m hoping to speak with the builder and get some clarification on his thinking. Thanks again.

Jeff
Click to expand...

I know many may think this is just me being sarcastic, but the reality is that in most all instances where a gross weight is listed above the value recommended by the designer, it was done because when the airplane was initially weighed and that empty weight :eek: was factored against what the builder weighs, what some of their desired passengers weigh, and how much baggage they want to carry when those people are aboard, becomes the driving factor on what gross weight gets chosen.
Doing any analysis of the likely performance degradation or impact on structural loads is rarely part of the process.

A fairly common mantra within the RV community is "Van's way over designs the airplanes so higher weight is not a problem" and also "I fly mine at such and such a weight and it does great"

In reality, increasing the gross weight by 50 lbs is probably not going to be a major factor in most situations... But there is a big difference between 50 lbs and 200 lbs.
 
Thanks

Scott,

I couldn’t agree more. It’s interesting because in the builders wt and b examples post build, he uses 215 lbs for himself, and a 200 lbs pax. With full fuel he just cracks 1700, but none of his examples approach 1850. My wife and I weigh 165 and 135, any will rarely be above 1650. I’m worried more about resale, as we are lighter than average. I’d love to speak with the builder, as my theory is that he might have made some modifications in strength or skin thickness that mirrors some of the newer kits. He’s an engineer, and may have come to the conclusion that his airplane is stronger than a typical -6. Just my theory. Thanks so much for your input. Best regards,

Jeff
 
Jeff Bost said:
S. I’d love to speak with the builder, as my theory is that he might have made some modifications in strength or skin thickness that mirrors some of the newer kits. He’s an engineer, and may have come to the conclusion that his airplane is stronger than a typical -6. Just my theory. Thanks so much for your input. Best regards,

Jeff
Click to expand...

The chance that the builder did this is pretty much zero! I suspect most don't realized exactly how much work goes into that kind of analysis.

Larry
 
6A

I listed mine at 1850but never flew it over 1700 lbs. I used to go to Baja a lot in the day and it looked overweight with the things stuffed in it. In the day ramp checks we’re very common.
 
1135lb is pretty porky! It would be worth finding out where all the additional weight is. It is usually in added equipment that might not be used often and can be removed. A slick paint job can add a few lb also. My 6 weighed 1127lb when it was built, but it has an angle valve motor, heavy Hartzell prop and a few other features. It is possible to reduce the weight but at a cost. It now weighs around 1040lb empty, I would suggest budgeting on $200/lb and hope to do better, especially if the removed equipment can be sold.
 
I think a lot of builders take the aerobatic weight and work backwards to utility or normal category to come up with 1850. My 6A comes in at 1041 with a 0-320 and a FP metal prop. I do a Weight and Balance on every ship I've purchased. As others have mentioned, take it easy when you are heavy.
 
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