So you want to do your first scratch build.

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neil_w

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As for the metric measurements, that comes from Open Rocket (body tube database is listed in metric sizes)
Not if you have your preferences set to inches.
1594304081665.png

As for 3D printing and CAD... yep, mm. Unit conversions are fun! :)
 

Chad

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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

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

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Here's an idea that I've been working on, but can't seem to get it to work. Even without a motor, CP is ahead of CG.
View attachment 423834
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.

Dart.jpg
 

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boatgeek

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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.

View attachment 423851
@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.
 

neil_w

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The situation is not quite as dire as in Lakeroadster's post above. Here it is, with some materials correction, and realistic motors:
1594309975098.png

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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neil_w

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I just tossed it together to show him it would fly.... I didn't know it was a competition model.
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.
 

Alan R

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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
 

neil_w

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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.
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

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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.
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 ...

10 Judges Score.png
 

rklapp

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RKLAPP, not sure what you mean by "exposition"?

I believe Mike has had the drawings for years, and never got around to digitizing them.

What's wrong with a lithograph print? I would assume they would be more accurate than a photocopy.. (unless you mean something else?) Drawings rarely go thru a lithograph process, that's more for art work prints..

can you post a pic of the plans / drawings?
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?
 

rklapp

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Kinda reminds me of the Low-boom SST with 3 fins and no neck (and no pods).
 
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