Gregory asked:
> I was thinking about a model "C", however I question whether
> the useful load on a "C" model would be enough to carry a
> full load of gas and two adults. I know many things factor
> into this question, so the answer can be general.
Gregory,
Yep, useful load is the key question for many of us.
The starting points are the gross weight. As originally certificated, the
415-C and 415-CD are both LSA compliant as long as they were never converted
to be 415-D (or later) models. (Though it is legal to change them up to be
415-D then change them back, once changed they are never eligible as LSA
again.)
If you have an FAA 3rd class medical and expect to keep it for a long time,
you might go looking for any model from 415-D onward as they allow up to
1400 pounds gross weight or, for the Forney F-1A, Alon and Mooney M-10
planes 1450 pounds. A caution is that many of those later planes also have
enough higher empty weight (accessories, paint, metal skinned wings, etc.)
that they have no more useful load than many 415-C and 415-CD.
So, back to the 415-C and 415-CD. As certificated, they can fly at up to
1260 pounds. However, there's an STC available that allows you to make all
the model D conversion changes yet have a max gross weight of 1320 pounds
and keep the plane eligible as a Light Sport Aircraft.
Now, lets go back to the empty weight.
When the planes came out of the factory, they often had weights in the 830
range. That would now give you 490 pounds of useful load. Sort of
unfortunately, many C and CD models have gained weight from paint,
upholstery improvements and additional instruments and radios taking them up
to around 900 pounds empty weight. Many of these weight gains are
reversible - you'd have to evaluate a prospective purchase carefully to see
if you can/want to reduce its weight sufficiently for your purpose. For
example, I'd hate to buy a plane with a beautiful paint job then strip the
paint just to reduce the weight. Doing that to an ugly paint job might
improve both the appearance and weight of the plane.
I saw in a TV special that the average weight of men inducted into the Army
in WW2 was about 156 pounds. Compared to that, the FAA standard allowance
for men of 180 pounds is pretty liberal. Compared to those WW2 guys, I
count as two people all by myself (though finally making progress downward).
So, let's figure:
I'll figure this three times based on 900 pounds, 870 pounds and 840 pounds:
1320-900 = 420 pounds useful load
180 * 2 = 360 pounds
420-360 = 60 pounds for fuel (10 gallons)
Keeping a four gallon VFR reserve, six gallons will give you a full hour of
flying time.
1320-870 = 450 pounds useful load
180 * 2 = 360 pounds
450-360 = 90 pounds for fuel (15 gallons)
Keeping a four gallon VFR reserve, nine gallons will give you just shy of
two hours of flying time.
1320-840 = 480 pounds useful load
180 * 2 = 360 pounds
480 - 360 = 120 pounds for fuel (20 gallons)
Keeping a four gallon VFR reserve, twenty gallons will give you a solid
three hours of flying time.
Now, you have to refigure these numbers based on your own personal weight
and that of your most probable passenger(s). Be advised that the 415-C and
415-CD are equivalent for these weight and balance discussions. Be sure to
compare these numbers with all the other LSA eligible planes, few of which
do better.
Ed Burkhead
http://edburkhead.com/Ercoupe/index.htm
ed -at- edburk???head. com (replace -at- with @ and remove the "???" and
extra space)
