Min diam fin design

[cjl]

Nope - that was actually Adrian's Parrot altimeter. 200Hz and 0.02G resolution. That curve simply comes from the measured deceleration during coasting, plus some fancy math to account for some variables (like the changing air density as it coasted to almost 12k)

 

[mudmanc5]

2 fin materials I can use one is lighter but 1/8" the other is 1/16" but will be 4-5 grams heavier when finished. So my question is whats more important the weight or aero the thinner material is much easier to shape therefore giving me a nice Sharp edge

 

[Chicagonative17]

2 fin materials I can use one is lighter but 1/8" the other is 1/16" but will be 4-5 grams heavier when finished. So my question is whats more important the weight or aero the thinner material is much easier to shape therefore giving me a nice Sharp edge

I believe you want it thinner for aerodynamics more than weight. If you run a sim, 5 g. more isn't affecting the performance much. You want to have the absolute least drag as possible, drag is a performance birds worst enemy. Because the fins have to cut through the air, I think the aerodynamics is more important than weight.

 

[cjl]

Go with the thin stuff.

There are other ways to save weight, though a well made 38mm minimum diameter rocket will likely come in underweight for optimum altitude.

 

[Chicagonative17]

57 inches!!! Thats tall if you are going for altitude.

For a 38mm rocket I would say...

-6" root
-2" tip chord length
-1" sweep forward from back of fin
-3" sweep backward from front of fin
-3/32" or 1/8" thick G10 (1/16" if you decide to tip to tip composite the fins)

I recently made a MD 38mm rocket on rocsim. I have a high performance style fin, but I didn't follow exactly what I quoted you...both will work well, though. Its also dual deploy and ONLY 45".

I like this design so much, I might make it...so I named it...Aphelion. That is a term used for the point in orbit furthest away from the object being orbited.

View attachment Aphelion.rkt

 

[jraice]

5 grams! Thats what a paperclip... Geez you guys are nuts if you try to reduce the weight by that much...

 

[cjl]

By the way - if you care a lot about high altitude, make sure the rocket has as smooth of a finish as possible - a polished finish really helps reduce the drag, and will make much more of a difference than a few grams ever will.

 

[mudmanc5]

What vendor has the missile works rrc2 mini ? Heck for $79 I can swing that I went to missile works site and it wasn't listed.

 

[Chicagonative17]

Its not on the site because they just reconstructed it. If you call him, I bet he would have one for you.