How do I get fix the angle of attack issues in this model rocket design? Thanks Grandpops
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lakeroadster
When in doubt... build hell-for-stout!
Your 18.4 mpg "off the rod" needs to be >30 mph. You need a more powerful booster motor.
Indeed. This is an incredibly heavy rocket to be flying as a 2-stager off D12/E12 motors. It is also overstable. Do you really mean to have a 2 oz nose weight in there?
Here's the relevant bit of the Estes motor table:
So for the D12, max recommended liftoff weight is 14 oz. You're at 19.1 oz. For the E12, max lift-off weight is 16 oz; you're at 20.4. So, even without the 2 oz nose weight, you're still too heavy.
Ultimately, the max lift weight in the table is a rough guide; the velocity off the rod given in OR is a more reliable number. But as @lakeroadster points out, that number is way too low. The rocket is coming off very slow and waggling around a bit until it stages and gets moving properly.
Flying an underpowered 2-stager is worse than a single stage, because if it tilts off the rod and then stages you could have a cruise missile on your hands. Unless you can significantly reduce the weight of this rocket, I wouldn't fly it as a 2-stager. There is no combination of BP motors available for sale that will make that rocket go, unless you rebuild the booster to take a 29mm motor and you can put an E16-0 in there.
Thanks for the feedback, very helpful. Still learning and adjusting this design.
Does the max lift off weight include the engine?
Yes.
But remember, the chart is a useful but really just a rough guideline. Using something like OpenRocket can give you a more precise answer, taking into account different launch rod lengths and other things.
Does the rocket need both a baffle and cloth heat shield? Or one or the other?
lakeroadster
When in doubt... build hell-for-stout!
It needs recovery wadding, or a cloth heat shield, or a baffle.
Most folks would use wadding (sheets or blown in cellulose insulation, aka: dog barf), for LPR.
For MPR / HPR a Nomex sheet (or similar), backed up with dog barf or a Nomex sheet using a baffle.
The other way to get faster "off the rod" velocity is a longer rod/rail.
Also remember "effective rod/rail lemgth" is from top lug/button to top of rod/rail. NOT the overall length of the rod/rail.
Also remember "effective rod/rail lemgth" is from top lug/button to top of rod/rail. NOT the overall length of the rod/rail.
Does anyone have a good design for cluster cables, 2 and 3 engines? Thanks in advance.
What is the best and easiest software to generalate G-code for fins and centering-rings on a laser cutter? Will they import a CSV or OBJ file from OpenRocket? Much thanks in advance.
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