sweep angle for a rocket fin?

[KarimMurad]

any idea how to calculate the sweep angle for a rocket fin?

 

[mccordmw]

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.

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

 

[KarimMurad]

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.

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.

 

[FredA]

Target 70-degrees.
Seems to be the accepted best angle for all flight profiles.

 

[mccordmw]

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:

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

 

[mccordmw]

That rule of thumb actually seems to give some really large fins, IMO. I'd go with 1 diameter for semispan (S).

 

[KarimMurad]

Thank you it's really very beneficial. I appreciate your help.