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Message
Before you go adding
weight to the tail - my RV's forward CG (empty) was 1/8" forward of Van's Limit
(in addition to weighing 1170 lbs). I called Vans to check on the C.G.
limit and as long as it was the "forward" limit there was no concern. They
fretted more over my weight than the C.G.
Thanks for the comments. I'm only .3" in
front of the forward CG limit according to my spreadsheet, and it
seems that this is a pretty common problem for people who put O-320 engines in
their RV-3's, since the plane was designed for a 125 hp engine.
A friend with an O-320 RV-3 just told me his empty weight is 822 lbs, and he
publishes a gross weight of 1280, though he keeps aerobatics below Van's
recommended 1100 lb gross.
I called Van's yesterday, and talked to one of the
engineers that designed the "B" wings for the RV-3. I am curious to
know if they updated the gross weight limits when they redesigned the
wing. Unfortunately, he probably wasn't at liberty to answer that,
and said he'll ask Van when he gets back from Oshkosh. I'll be
surprised if they raised the limits any, but since the B wing
is considered superior to the old wing, I feel OK about it, especially
since everyone seems to be flying them at higher than recommended gross weight
anyway.
I'm going to go to the airport today, and make some
measurements of these moment arms that are published in the manual. In
particular, I'm interested in seeing where the single moment arm that they give
for the baggage compartment actually falls. It's a big baggage
compartment, and I'm guessing it's in the middle of that area. Once I
confirm those figures, I can decide what to do. It's quite likely that I
won't have to add any weight at all. Using the general purpose baggage arm
that's given, I can add 6 lb of weight as baggage, and be within the forward CG
limit. Since I'll always carry tie-downs, tools, plugs, and oil
(when I get out of my test period), I'm sure it will add up to 6 pounds. I
can also contain this stuff in the far aft end of the compartment, where it
probably won't even need to weigh 6 pounds to make the CG
limit. Bottom line, it seems like it will all work out
OK.
Cheers,
Rusty (when pigs fly)
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