Design > Stunt design
Odd question on a profile model: Keep the inboard side without protuberances?
Brett Buck:
--- Quote from: Howard Rush on December 29, 2023, 07:41:06 PM ---I wouldn’t expect much aerodynamic difference between having stuff on one side of the fuselage vs. the other, but the mass distribution may matter.
--- End quote ---
That is one likely issue here, putting all that weight centered ~1" from the centerline of the airplane may overdo the "save tip weight" effect, and require some added to the inboard wing.
I am not sure I would assume the leadouts are going to fix the thrust offset. I know you are skeptical about my assertions about thrust vectors, but I would kick in, or at least make provision for, a good bit of right thrust. Unfortunately the thrust varies all over the place, so no guarantees that you can completely resolve it with thrust offset.
Same effect makes putting the motor straight ahead likely to make for exciting takeoffs, immediate left turn on launch, like an All-American, just not as bad.
Brett
Howard Rush:
--- Quote from: Brett Buck on December 29, 2023, 07:51:07 PM --- That is one likely issue here, putting all that weight centered ~1" from the centerline of the airplane may overdo the "save tip weight" effect, and require some added to the inboard wing.
I am not sure I would assume the leadouts are going to fix the thrust offset. I know you are skeptical about my assertions about thrust vectors, but I would kick in, or at least make provision for, a good bit of right thrust. Unfortunately the thrust varies all over the place, so no guarantees that you can completely resolve it with thrust offset.
Same effect makes putting the motor straight ahead likely to make for exciting takeoffs, immediate left turn on launch, like an All-American, just not as bad.
--- End quote ---
I was thinking of the effect of skewing the principal axes. If that causes the leadouts to move aft to trim the airplane, I guess that would give more thrust offset. I hadn't thought of thrust offset. I've been using 2 degrees of motor offset, copying you-know-who.
Brett Buck:
--- Quote from: Howard Rush on December 30, 2023, 02:35:19 AM ---I was thinking of the effect of skewing the principal axes.
--- End quote ---
I think putting a bunch of weight well to the right would skew it to the right (positive around geometric Z), which suggests you might need the leadouts further forward, rather than back, wouldn't it? I still think you would ideally line up Y with the circle "r vector". Or were you thinking of something else?
Brett
Howard Rush:
--- Quote from: Brett Buck on December 30, 2023, 11:54:09 AM --- I think putting a bunch of weight well to the right would skew it to the right (positive around geometric Z), which suggests you might need the leadouts further forward, rather than back, wouldn't it? I still think you would ideally line up Y with the circle "r vector". Or were you thinking of something else?
--- End quote ---
You are correct. I was off a little on the sign.
Carl Cisneros:
Bill
here are a couple pics of the front end of my 60 size profile electric Time Machine I built last fall.
flies a treat. No wierd stuff and pulls pretty dang good on the lines in all maneuovers.
The battery box and motor mount area is for a 38 special electric conversion from Bodaks.
Carl
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