By hook or by crook, it will fly!
Just curious, does the CAD model tell where the GG is wrt the engine centerline? Because, irrespective of the external aerodynamics, an offset GC will induce a pitch/yaw moment during thrusting.
Just curious, does the CAD model tell where the GG is wrt the engine centerline? Because, irrespective of the external aerodynamics, an offset GC will induce a pitch/yaw moment during thrusting.
Even if so, after construction, it could be useful to mount a shaft into the motor mount to check balance.
What I love most about this is that when this comic came out, paleontologists didn't have a name for that part. So now the actual name for it in scientific literature is "thagomizer".So sad what happened to Thag Simmons.View attachment 633758
Just curious, does the CAD model tell where the GG is wrt the engine centerline? Because, irrespective of the external aerodynamics, an offset GC will induce a pitch/yaw moment during thrusting.
Even if so, after construction, it could be useful to mount a shaft into the motor mount to check balance.
Given the, um, uncertain nature of the aerodynamics, I would get that lined up so that you don't induce any un-necessary moments. If you add nose weight, put it on the green side.
Would a swing test be inappropriate?
If it were me, I'd add 18" to the length, and put "invisible" clear plastic fins on - enough to quadruple the fin area. Belt and suspenders FTW.Some rockets call for a heads up launch. This will call for heads up, fingers crossed, and butts clenched.
If it were me, I would shift the MMT laterally to align with the CG and apply a slight of fin cant to try to approximately counter the nose cone angle. Canted fins don't seem to be ruled out by the cartoon as drawn, and are certainly in line with the cartoon as conceived.
But then, if it were me, I wouldn't build it; I'd sit back and let some lunatic do it.
If it were me, I'd add 18" to the length, and put "invisible" clear plastic fins on - enough to quadruple the fin area. Belt and suspenders FTW.
Also, for structure sake, I'd add an off-centering ring in section 2.
View attachment 633883
In Seattle, I've grown up with Gary Larsen as my native and most beloved cartoonist. His intoxicatingly proportioned cartoons will lead you down the garden path of enjoyment all day long. I know you, and know you will succeed in this project - but maybe just not right away.With all due respect: You've missed the entire "mission" of this rocket: "To build the rocket exactly as drawn by Gary Larsen."And in regard to Lexan fins...
Perhaps "for structure sake" was not the way to say it. I'm thinking of the mitered joints, and the possibility that even simple handling could knock as unsupported edge-to-edge joint apart. So it's not for overall strength, but just to keep that piece still.Virtually zero loading on these pieces due to the 1" dowel.
The fin leading edges are not straight, they have a slight arc if you are going for accuracy.
With that in mind, if it flew straight and true... that wouldn't exactly be "scale," would it?the entire "mission" of this rocket: "To build the rocket exactly as drawn by Gary Larsen."
Concur. My MIRV sustainers based on the Estes rocket of same name had extremely offset nose cones and never had any stability issues.Rockets with various offset nose cone designs seem to fly just fine. Admittedly this one is a little more off-kilter than most, but I tend to think that as long as the fins are straight and the motor is close to center of mass and/or drag, then it's likely fly pretty straight.... or if not perfectly straight, then not too far off line. I mean, there are lots of airplane-style designs with large wings that tend to arc over somewhat, and no one has a problem with them.
Canting the fins to compensate without really knowing in advance how the rocket is going to behave seems like a bad idea to me.
You could also try to contact @jflis and see if he has any good wisdom to impart from his time developing the Spitfire.
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