Could someone please explain how to bevel fins for a small BT-50 rocket? I can't imagine it will make much difference on my B motor flights but I would still like to do the best job I can If there is a hand tool available to aid me I wouldn't mind purchasing it. Also how do you round the top of the fins for better aerodynamics.Thanks
Beveling Fins
- Thread starter pepe
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morlock
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First, sand the leading and trailing edges at 45% on each side, eg:
Then fold a piece of sanding paper round to a small radius (1/4 of an inch, 400 grit is good) and pass it on the top edge. Finish with same sanding paper by smoothing any remaining edges.
Rounding these edges can increase apogee height by as much as 20 %, depending on the model. If you do the sims in Open Rocket, you have the option to use square, rounded or airfoiled fins. You can directly see what the impact is for your design.
Finally, the most important thing is to have fun, so if you feel like doing it, go ahead, but if you think it is a chore, leave them square and spend your time doing stuff you enjoy. Like flying the thing!
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| |Then fold a piece of sanding paper round to a small radius (1/4 of an inch, 400 grit is good) and pass it on the top edge. Finish with same sanding paper by smoothing any remaining edges.
Rounding these edges can increase apogee height by as much as 20 %, depending on the model. If you do the sims in Open Rocket, you have the option to use square, rounded or airfoiled fins. You can directly see what the impact is for your design.
Finally, the most important thing is to have fun, so if you feel like doing it, go ahead, but if you think it is a chore, leave them square and spend your time doing stuff you enjoy. Like flying the thing!
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Pepe:
Aerodynamically beveling fins on sub sonic rocket is truly a waste of time. What you should do is at least round the leading and tailing edges of your models. Any size model will benefit from this somewhat simpler step.
For Scale models with Beveled fins there are a number of ways to do it. simplest is to measure the length of the bevel you wish to sand. apply a line of vinyl tape along the cutoff line on both sides of the fin. Mark as closely as you can the center of the fin thickness and sand in long straight line strokes until you reach the center line on both sides.
Another method I use often for beveled fins is the construct them just like they are done on the full size vehicle. Two folded plates with a center spar or two center spars for dual tapers. The material can be anything from .010" Polycarbonate to File folder cardstock. I've used this method on LMR BT-80 size Clustered models all the way down to micro Nike Smokes.
Hope this helps a little
