Re: [gypsy-ul] Re: stay'n alive...
- Guys, you have to recognize that 99 percent of all performance
specs are pulled out of thin air for ultralights.
The designers however being smart enough to design the
plane in the first place are usually smart enough to insert
numbers that seem reasonable except in the case of designers
that saw the need to compete with other designers who were
obviously lying and exagerating about their own planes performance
or were unknowingly copying another designers numbers to
be competitive not knowing how accurate they might be.
Even in the rare instance where a designer would have used
NASA testing facilities to accurately document the performance
numbers, you must be aware that those numbers only apply to
that pilot, flying that plane built with exactly the same
streamlining, and weight and hp and prop efficiency at the
same altitude density etc. Even with the nasa supplied
numbers all the detail test dats isnt made available so
how would you know ? You cant.
I hope you are getting my message here. You must learn
to accept the numbers as VERY loose approximations of what
might be reasonable, be very skeptical, and know how
to cross reference the numbers to see if they pass
the sniff test. Over time you will recognize when
based on hp, weight, wing area etc that top speeds, stall speeds,
takeoff rolls, or climb rates make reasonable sense or not.
> From VULA you say... :-) Like this, another of Scott's groups... I
> know he rightly expects us to do our own research, but that was just
> mean, don't ya think? Not even a hint where to start... :-) Oh
> well, who cares about gross weight anyway; it just gives you more to
> worry over. Add another wing-rib to the length, I say. I can't find
> my own rear with both hands as far as airplane design, but I'd do it.
> --- In email@example.com, "George Bearden" <gab16@...> wrote:
> > > Span=32ft., Area=144sq.ft., Length=17ft., Height=8 1/2 ft.,
> > > Cruise=35-40mph., Stall=22mph., Red Line=55mph., Gross Wt.= N.A.
> > Hey! Fropm Kitplanes latest issue, info from VULA (I think):
> > Cruise, mph 45
> > Stall, mph 22
> > Rate of climb, fpm 450
> > takeoff distance, ft 150
> > landing distance, ft 75
> > Engine used Zenoah
> > hp 22
> > hp range 15-32
> > Fula cap 5
> > empty weight 225
> > gross wt 475
> > length 16
> > wingspan 32
> > wing area 144 aq ft
> > no. of seats 1
> > cockpit width, in 24
> > landing gear tail wheel
> > bldg. mat. F,T
> > beginner build time, hrs 300
> > no. completed, flown 15
> > cost of plans $40
> > estimated completed cost $2k-$5k
> > http://vula.org
> > (678) 290-0507
> > LSA legal
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