sweep angle for a rocket fin?

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Fin sweep angle is the angle between a perpendicular line and a line drawn from 25% of the fin root length to 25% of the tip length. I found a decent image on Google.

sweep-back-angle.png


Or do you mean you want to calculate the best sweep for a model you're designing from scratch?
 
Fin sweep angle is the angle between a perpendicular line and a line drawn from 25% of the fin root length to 25% of the tip length. I found a decent image on Google.

sweep-back-angle.png


Or do you mean you want to calculate the best sweep for a model you're designing from scratch?

Yes I want to calculate the best sweep for a model that I design.
 
Target 70-degrees.
Seems to be the accepted best angle for all flight profiles.
 
OpenRocket is your friend.

https://openrocket.sourceforge.net/

You'll be able to play with it to get what's best for your model. You want to get a stability margin of >1 (usually 1.5-2.0 range). There are several threads here on how to use OpenRocket. Plus, it's fun to play with and dream up designs. I prefer building from scratch myself vs kits. It's neat to launch something and think, "I dreamed that up!", when it flies beautifully.

The clipped delta is generally considered a great all-around shape. Here's a rule of thumb for dimensions:

rocket202.png


But that's a rule of thumb. Always calculate and sim yours to be sure.

That reference is from: G. H. Stine & G.W. Stine, Handbook of Model Rocketry (7th Ed.), John Wiley & Sons, Inc., Hoboken, NJ, 2004
 
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