REFLECTOR: Gross weights

[Pat Shea]

Kurt,

My take is that you can have three gross weights:

1) The one on paper. This one keeps you out of trouble
with the FAA and should be as high as justifiable.
Unfortunately you have to set this before your flight
testing, but better to be too high than too low...
Based on your HP, I'd use the factory's listed gross
weights for the XL or XL-5.

2) Structural load limits. This one is hard to define 
since it depends on the g loadings during the flight
and how hard/soft the landing is going to be. I
believe one of the reasons the factory increased the
Xl's gross weight on the -5 model from 2700 lbs to
2900 lbs was due to the carbon reinforced main gear
legs. I'd look to the factory to help you get your
head around this. For instance, I'd want to know if
the standard fuselage has more, less, or the same
structural load capability (including the gear) as the
XL. If it's the same, then I'd feel pretty good about
2700 lbs since there are lots of XLs out there banging
around at this weight.     

3) Performance limits. Once you're flying you can
steadily work up to the weight limits you're
comfortable with based on the actual performance of
your plane. Takeoff, climb, and braking performance
would be what I'd look at most.

FWIW, Pat

--- NMFlyer1 at aol.com wrote:

> Seemed like a good time to ask this question with
> all the W&B questions. 
> 
> I have a 173 FGE. Empty weight is supposed to be
> between 1250 and 1400 LBS. 
> With what I have done installing the aluminum 4.3L
> Chevy, Superfilling all the 
> flying & control surfaces,,, etc.... I should come
> in about 1400LBS. 
> 
> The thing is, I have 340 HP in a 173 for about the
> same weight as a 200HP 
> IO-360. 
> Where do I put my gross weight?  I know Bill
> Mulrooney put his V8 powered 
> 173RG at 2900lbs with his extra power (and lots of
> extra weight). I did get a tad 
> of advice from a factory rep. I was told to add up
> the empty weight of my 
> plane... full fuel... four-200LB people, and 200 LBS
> of baggage. Then add 100LBS 
> and use that number. The reasoning was that my plane
> will haul almost anything 
> with the extra HP, and you want to make sure that
> you are ALWAYS within W&B 
> on paperwork to satisfy the FAA and insurance toads.
> 
> Any input?  
> 
> Thanks   Kurt 



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