Not if you have your preferences set to inches.
As for 3D printing and CAD... yep, mm. Unit conversions are fun!
So you want to do your first scratch build.
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As for 3D printing and CAD... yep, mm. Unit conversions are fun!
Last night I was contemplating another ebay-in-the-nosecone concept and it reminded me of one of John's videos.
For scratch building advice, his website is one of the best resources i've found
https://www.jcrocket.com/howtolist.shtml
edit: i saw this thread in the recent posts section and didn't realize which forum it was made in until now. All my posts are me thinking in terms of HPR, sorry if my suggestions aren't very relevant
For scratch building advice, his website is one of the best resources i've found
https://www.jcrocket.com/howtolist.shtml
edit: i saw this thread in the recent posts section and didn't realize which forum it was made in until now. All my posts are me thinking in terms of HPR, sorry if my suggestions aren't very relevant
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lakeroadster
When in doubt... build hell-for-stout!
Add a motor mount, and a motor. Then add ballast to the nose cone to achieve the stability you're after.
I took the liberty of re-creating your rocket in Open Rocket. This one is a BT-60 based.
I'd suggest you start a build thread... looks to be a neat bird.
Good luck.
boatgeek
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@Senior Space Cadet (Replying here so as not to derail Neil's thread further.) You can move the parachutes and shock cord quite a bit further forward. If you're worried about them sliding down during boost, put a small CR just below them to hold them in place. You might look at going from 4 fins to 3. They aren't really helping you all that much and might reduce the total nose weight required. I like how the fins continue the nose cone shape.
The situation is not quite as dire as in Lakeroadster's post above. Here it is, with some materials correction, and realistic motors:
Still talking about 5 oz of nose weight in there, which is enormous for a nose of that size. Weighted nose weighs more than the rest of the rocket. Total weight allows for a real flight on a D12.
This assumes 1/8" very hard balsa fins, similar in mass to papered balsa. Un-papered light balsa would reduce weight further.
But doable. Much like a cone rocket, but without the benefit of base drag.
Addendum: could be worthwhile for a rocket like this to have the nose cone come down on its parachute. Don't want a mass like that doing its imitation of a wrecking ball at deployment time. Otherwise, nice long shock cord.
Still talking about 5 oz of nose weight in there, which is enormous for a nose of that size. Weighted nose weighs more than the rest of the rocket. Total weight allows for a real flight on a D12.
This assumes 1/8" very hard balsa fins, similar in mass to papered balsa. Un-papered light balsa would reduce weight further.
But doable. Much like a cone rocket, but without the benefit of base drag.
Addendum: could be worthwhile for a rocket like this to have the nose cone come down on its parachute. Don't want a mass like that doing its imitation of a wrecking ball at deployment time. Otherwise, nice long shock cord.
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lakeroadster
When in doubt... build hell-for-stout!
Dire? What was Dire?
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lakeroadster
When in doubt... build hell-for-stout!
16 oz
(and 7.5 oz in the nose)
Geeze.. tough crowd. I just tossed it together to show him it would fly.... I didn't know it was a competition or I would have spent more than 2 minutes on it.
16 oz with 7.5 in the nose is fairly extreme for a rocket of that size. I was only saying that it could be be a slightly less extreme, and weight could actually be brought down to where you could reasonably fly on a D. That's all.
ya, plus go to 3 fins. Maybe trim the height of the fins to reduce weight/drag (but that will move cp - play with it) i think i would suggest try simming a longer motor tube and an E instead of a D. (or sim a short aerotech E) I believe you could get a little better altitude, even with the additional weight.
yes, very cool design
3 fins actually reduces stability a touch.
D12 get you 340', E20 gets you 1010 ft, E30 gets you 1185 + ft.
Model is still rough, but this is decent starting point. Thanks to Lake for putting the initial model together.
lakeroadster
When in doubt... build hell-for-stout!
Let's hope @Senior Space Cadet optimizes the design further and then makes it into a reality. It would be an awesome scratch build rocket.
And apogee at 340' on a D-12...... one chute on the nose... and one chute on the fuselage... the visual wow factor would be ...
@Senior Space Cadet ... don't you love it when everybody starts screwing ... er .. assisting with your designs?
For the money, I would expect better diagrams, IMHO, I’ve found better stuff on the web for free. Just my opinion...
Am I allowed to post it?
Kinda reminds me of the Low-boom SST with 3 fins and no neck (and no pods).
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