Hi Guys Does anyone have a good simple for calculating the necessary fin area for a rocket?
Thanks
Fred
Thanks very muchThe normal fin rules of thumb...
3 fins
Fin Area (each) = 0.17 * [(rocket_diameter+0.5)*rocket_length]
4 fins
Fin Area (each) = 0.13 * [(rocket_diameter+0.5)*rocket_length]
Those are in inches and square inches
Root chord = 2 x rocket_diameter
Tip chord = 1x rocket_diameter
Hmm, I get different numbers... how long is this rocket? Assuming a 10:1 ratio, the rocket would be 26 inches in length.So for a BT-80 Root cord is 5.2 inches.
Tip cord is 2.6 inches.
Semi span would be 5.2"
This is aproximate of course
Thanks
fred
The rocket should be about 28.75 inches long Man math makes my head hurt.Hmm, I get different numbers... how long is this rocket? Assuming a 10:1 ratio, the rocket would be 26 inches in length.
Root = 5.2 in
Tip = 2.6 in
Area(3) = 13.7 in^2 (each)
area(4) = 10.48 in^2 (each)
The formula for area would be:
area = (root+tip) * span / 2
Therefore:
span = area*2/(root+tip)
For 3 fins, that'd be 3.51 in.
For 4 fins, that'd be 2.69 in.
I'll keep it in mindAlso remember that a span increase is more effective than a chord increase when considering the fin's overall effectiveness... OL JR
How do these formulas change if at all when using metric measurement. I can use imperial but find it confusing. I mean inches no disrespect eitherHmm, I get different numbers... how long is this rocket? Assuming a 10:1 ratio, the rocket would be 26 inches in length.
Root = 5.2 in
Tip = 2.6 in
Area(3) = 13.7 in^2 (each)
area(4) = 10.48 in^2 (each)
The formula for area would be:
area = (root+tip) * span / 2
Therefore:
span = area*2/(root+tip)
For 3 fins, that'd be 3.51 in.
For 4 fins, that'd be 2.69 in.
I believe the formula can be used using either imperial or metric figures..metric would make it easier to measure the final results..How do these formulas change if at all when using metric measurement. I can use imperial but find it confusing. I mean inches no disrespect either
Cheers
Bill
The only thing that would change for metric (other than the units) is how much you add to the diameter... The formula adds half an inch, which is 1.27 cm or 12.7 mm.How do these formulas change if at all when using metric measurement. I can use imperial but find it confusing. I mean inches no disrespect either
Cheers
Bill