Jim Williams wrote:
Richard,
What software did you use to design the aircraft? The aircraft
looks pretty damn good.
Jim Williams
Mr. Williams is obviously a man of good taste and culture.
Probably an Ace pilot and a handsome devil too...
Thanks, Jim.
CAD:
The drawings are done with Design CAD 2000. My choice.
I started with the DOS version of DC - golly - 25 or 30
years ago, now. That's a really nice package too. IMHO,
way better than Autocad V10, (which I also bought way back
when?).
Both put lines on paper, but so does a pencil.
Drawing a smooth spline, on the other hand...
There was a real cool release of this program a while back
under the name ModelCAD. It was optimized to design model
airplanes(!). Tapered wing rib patterns et al.
I haven't played with it, but I'd love to if anybody out
there has a copy.
I don't think it matters much what CAD package you pick,
drawing in 3D is a little higher hurtle to get a leg over.
Or maybe it's just a question of what you learn first?
I know kids who can do beautiful 3D, but can't project
a 3 view on paper. Dunno...
Animations:
The animations are made from CAD screen shots.
(rec.aviation.homebuilt - NOT - Industrial Light and Magic)
Draw, render, save pic,
move parts, render, save pic,
repeat until done,
or until you goof,
or just can't stand it any more.
The DC programing language is BASIC-like (rather than
Autocad's Lisp interpreter?). I haven't tried to write
anything to do this kind of animation, but it's certainly
possible.
For any kind of ILM style animation, I think you'd have to.
The elevator and aileron animations are only eight frames
each (IIRC?). Four for each side. They are simply
repeated in the reverse order to show the return paths.
They were stitched together with GifAnimator.
That part is pretty simple, really.
Analysis: (and back on topic?)
The stress calculations are provided by a custom program
(originally published in Sport Aviation a LONG time ago).
I got it working (I think), and added a menu system to
allow easy editing of wing parameters, weights, G limit,
material strength, spar width, etc.
Plug in your numbers and it grinds out the details.
One of the things it creates is a spar size table that
_is alleged_ to be minimum material dimensions to carry
the given load.
But like Stealth, I wonder if it can be trusted!
And, like Stealth, I'd like to have it evaluated by
someone who knows what they are doing before diving off
the deep end.
So...
I thought of one point that might could be calibrated -
Vans RV-9.
IIRC, RV-9 spar caps are milled from a single bar of aluminum
and stepped thicker at the root. We also know how thick the
spar shear webs are - from the plans.
All we'd need the spar dimensions from the plans,
and the following data:
Span [ft] [ ] Span Load [lb/ft] [calc]
Area [sqft] [ ] Area Load [lb/sqft] [calc]
Chord root [ft] [ ] RN root [mil] [calc]
Chord tip [ft] [ ] RN tip [mil] [calc]
Chord MAC [ft] [calc] RN mean [mil] [calc]
Aspect [#] [calc] Max CL [#.##] [ ]
Gross Wgt [lb] [ ] Stall Speed [mph] [calc]
Design G's [#] [ ]
Wing Thick[%chord] [ ] Spar Compr [psi] [ ]
Cap Width [in] [ ] Spar Shear [psi] [ ]
Any takers?
Richard