RV-6 MTOW

I'm guessing this question has been answered before ,but,,,I was just browsing the vans sight and noticed the MTOW for the A model is 50 lbs higher thn the taildragger,,,,???

The prevailing opinion seems to be that the difference is due to the different strength of the two gear configurations. I haven't seen factory confirmation.

[edit]Hey, I just noticed this is my 2000th post!

I've just been looking at a few of the POH's around, the MTOW seems to be very fluid, one was up at 2000lbs , I was considering calling mine 1800lbs in normal cat and thinking that was really pushing it ,,,

I remember reading somewhere that when Van's were deciding what gross weight to recommend for the RV-7, they looked at what people were typically using for the -6, and that was about 1800lb.

Maybe myth, but they seem to work fine with that. I would be less relaxed about exceeding Van's recommendations for aerobatic gross.

Mark Albery said:

I remember reading somewhere that when Van's were deciding what gross weight to recommend for the RV-7, they looked at what people were typically using for the -6, and that was about 1800lb.

Maybe myth, but they seem to work fine with that. I would be less relaxed about exceeding Van's recommendations for aerobatic gross.

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Very much a Myth

The gross weight is chosen early on in the design process (as it is with any properly run aircraft design project), and all of the structures engineering is done based on that weight.

The idea that the airplane gets built, put on a scale, and then a reasonable amount of useful load added to teh empty weight to determine the approved gross weight is totally false.

Gross weight moving targets

This is always an interesting subject I find as well. If you go on Vans' website under News and Events, Archives, and find the article about John Johansons' East and West circumnavigation of the globe, you will find Van himself approved John for a 136% increase in the gross weight of his RV-4 for his record attempt. This works out to 2,040 lbs on a normal 1500 lb gross weight, this was done for both the East and West circumnavigation flights. There is no other mention of other flight restrictions for this at the time such as limiting operations to Green arc air speeds, G limitations etc, which you would think would have been in place for safety reasons, but very interesting regardless. These posts always spark very lively discussions and opinions back and forth.

Got a reply from Vans , basically as we know we can pick whatever weight we want , but it effects a heap of things. Just wondering if anyone has had CG issues by having it loaded up and running the fuel tanks low?

M Wreford said:

Got a reply from Vans , basically as we know we can pick whatever weight we want , but it effects a heap of things. Just wondering if anyone has had CG issues by having it loaded up and running the fuel tanks low?

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You've gotta run the numbers for your airplane.

There are so many variables between engine, prop, paint, and other factors that there are substantial differences between airplanes. Mine, with a wood prop and a light engine can be loaded aft of the CG limit. Others, with a heavy engine/prop combo, not so much.

Kyle Boatright said:

You've gotta run the numbers for your airplane.

There are so many variables between engine, prop, paint, and other factors that there are substantial differences between airplanes. Mine, with a wood prop and a light engine can be loaded aft of the CG limit. Others, with a heavy engine/prop combo, not so much.

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What am I missing about this statement??........

gasman said:

What am I missing about this statement??........

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He's saying it's easier to get into trouble with a light engine and prop than with a heavy engine and prop. Read the "can load" as "it's possible" and not as "permissible". It's dangerous to load aft of the aft CG limit,

I would've thought having more weight hanging off the nose would make it possible to load more in the aft locker before you run into issues,,,,my question was regarding the problem of the CG moving further aft as you burn off fuel, and finding you've run out of forward stick at an in opurtune moment , I'm looking at using an 0 320 and metal prop, and keeping the build as light as possible, hopefully in the 1000-1050lbs range, I'm considering what I'll post as the MTOW and it's looking at being 1700lbs at this point but I'll have to see where it ends up with nil fuel , I've looked at all the other vans aircraft and the six is the only one that has a lower weight for the taildragger, so I'm pretty comfy with going at least to 1650lbs

As Kyle says " it is hard to over gross weight a six. It is real easy to get it out of CG when you burn the fuel out of the tanks!" Mine is an O-360 with a metal prop empty weight 1100 lbs. with me 210 a passenger 260 full fuel 232 and 50 in the baggage gross weight is still not an issue. Take the passenger out load up the baggage and empty the tanks and the tail end falls out of the sky on landing.

John Morgan

I believe the 6 came out before the 6A and when they added the 6A they added the 50lbs for the nose wheel, I suspect future models they planned ahead of time for the nose wheel in the gross weight figures.

FWIW - My 6 is just in Phase 1 W&B testing now, I set my gross at 1750 and my empty weight it 1065. I have a light weight Catto composite prop and worried about aft CG through the build and did what I could to keep weight forward.

I'm flying my 1750lb gross within CG during my Phase 1 testing but it is possible to reach max most aft CG well before I hit my gross weight. My most aft CG tests calls for min fuel and maximum baggage which hits my AFT CG ARM at a weight of 1585. This was the worst case AFT CG test I could setup on my plane that I will be flying in my Phase 1 (6 gal fuel 184 lb pilot, 220 lb pass and 80 lbs baggage) .

As other have said it is a little different on each plane, CS props up front help keep the CG more forward for these low fuel high baggage weight tests on the tail draggers.

russcoburn said:

I believe the 6 came out before the 6A and when they added the 6A they added the 50lbs for the nose wheel, I suspect future models they planned ahead of time for the nose wheel in the gross weight figures.

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I think it's more complicated than that - the main gear structure gets bolted to the main spar and fuselage such that it can likely bear more weight during a botched landing than the engine mount gear sockets will tolerate. This is speculation on my part, of course, but I wanted to point out that this issue isn't quite as simple as it would appear.