Fins attached to pods, I expect, to that they can be set at the positions and angles they need to be, rather than attached to a regular tube wall and radiating from the center.
Neil_W's half-baked design thread
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The body is easy; the nose is more interesting.
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Very interesting (especially to me as likely over 90% of my rockets have square bodies and 4 sided pyramid nose cones.)
How valid do you feel the aerodynamic stability calcs are for the sim?
I am curious how much an "issue" the flat sided nose cone becomes when angle of attack goes mildly over zero, as might be expected with a 5-10 mph wind gust, as well as the flat sides of the body. FWIW, my mind sim suggests either (especially the cone) likely throws the CP forward.
One hard part is what DIAMETER standard cylindrical rocket do you compare this with? a cylinder that would fit INSIDE the square body rocket, one that would fit OUTSIDE the rocket, is something in between.
You are perilously close to ruining my excuse for not learning to use OpenRocket!
boatgeek
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I have typically used an equivalent area cross section. That would predict form drag properly but would underpredict surface friction and whatever extra drag comes with the sharp corners. Equal cross section perimeter might be better. That said, I also didn’t want to give more credit than was due to the fins, so there’s definitely some mind sim to be done here.Very interesting (especially to me as likely over 90% of my rockets have square bodies and 4 sided pyramid nose cones.)
How valid do you feel the aerodynamic stability calcs are for the sim?
I am curious how much an "issue" the flat sided nose cone becomes when angle of attack goes mildly over zero, as might be expected with a 5-10 mph wind gust, as well as the flat sides of the body. FWIW, my mind sim suggests either (especially the cone) likely throws the CP forward.
One hard part is what DIAMETER standard cylindrical rocket do you compare this with? a cylinder that would fit INSIDE the square body rocket, one that would fit OUTSIDE the rocket, is something in between.
You are perilously close to ruining my excuse for not learning to use OpenRocket!
First and foremost, please note the static margin shown on the OR screen grab. This makes it painfully obvious that the simulated stability is useless.Very interesting (especially to me as likely over 90% of my rockets have square bodies and 4 sided pyramid nose cones.)
How valid do you feel the aerodynamic stability calcs are for the sim?
I am curious how much an "issue" the flat sided nose cone becomes when angle of attack goes mildly over zero, as might be expected with a 5-10 mph wind gust, as well as the flat sides of the body. FWIW, my mind sim suggests either (especially the cone) likely throws the CP forward.
One hard part is what DIAMETER standard cylindrical rocket do you compare this with? a cylinder that would fit INSIDE the square body rocket, one that would fit OUTSIDE the rocket, is something in between.
You are perilously close to ruining my excuse for not learning to use OpenRocket!
Also, I have no doubt that you're right about the nose pyramid pulling the CP up. Mainly, I'm confident of that because an ordinary nose cone does the same thing.
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I looked at it and thought it was a bit weird, but I am not a regular user. My MindSim does pretty well, as mentioned most of my rockets are square, and I would say that 95 percent are stable (kind of similar to their designer!)
Most are probably a bit overstable, but I haven't really experimented enough to push the envelope.
More OpenRocket abuse: Alcubierre 2
Yes this is hard to do. No, it won't produce a usable flight simulation.
Yes this is hard to do. No, it won't produce a usable flight simulation.
NTP2
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If I say please enough will you build it?
Not this particular one, no. I'm generally not too interested in revisiting things I've already built.If I say please enough will you build it?
NTP2
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Ohhh I thought that the 2 was just decoration not a actual designation.
It looks even better in person, and flies nicely (except for that little bit at the end).
lakeroadster
When in doubt... build hell-for-stout!
Kind of a Alcubierre meets Kessel Runner... cue the Barry White music... and the next thing ya know, 9 months later... Alcubierre 2
NTP2
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Or Kessel runner jr…
Hey now, this is a family forum.
Obviously this particular design was derived from my experiments trying to enter Kessel Runner into OR. Now that I have the technique down, I'm going to play with it. This is the first and most obvious idea that came to mind. I have a modification to make that will make it look better (I think).
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May be time to break out the latex paint…..
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ironically, this is likely a topic that SHOULD be discussed by families.Hey now, this is a family forum.
What is that saying, “Familiarity breeds”?
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Only in Alabama..., where marrying your cousin is apparently OK.
It's OK is a surprisingly large number of states.
[never mind, see next post instead]
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That's better. It's not 100% accurate but I believe it's pretty darned close.
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terryg
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Build it!
That is so cool, reminds me of an MS Escher drawing! I love it!
NTP2
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That is awesome!
It make my eyes hurt. Build it.
Tweaks. Trying to decide if this thing would have a chance of surviving a landing. I enlarged the ball but now I'm having my doubts about that (previously used ping pong ball size).
lr64
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What's the ball for? Ball in a cage? You're supposed to whittle those out of one chunk of wood. ;-)
Those fins break my brain. I think you'd have to make them pretty sturdy. Alternatively, dual deploy with an enormous main chute coming out at 200 AGL. I agree that you should build it.
If it was a real spaceship, I'd hesitate to imagine what the interior was like.
Those fins break my brain. I think you'd have to make them pretty sturdy. Alternatively, dual deploy with an enormous main chute coming out at 200 AGL. I agree that you should build it.
If it was a real spaceship, I'd hesitate to imagine what the interior was like.
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Getting those outer fins parallel to the long axis of the rocket would be a challenge for us mere mortals, but after reviewing your AVALON build just a walk in the park for you.
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The trail fin edges sweep forward, so shouldn’t impact the ground as first contact.
Moving the fins forward 1-2 cm wouldn’t hurt.
Alternatively, slightly shorter motor mount and let the motor and hook extend 1-2 cm further back.
Given length of rocket effect of such changes on stability should be minimal, certainly nothing a bit of nose weight couldn’t easily correct.
The perfect Hexagon on the tail view is really cool and something I should have (given 6 evenly spaced “strut-fins) but did not expect!
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