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Tau Zero
03-23-2009, 12:03 AM
In a previous post to the BARCLONE section here on YORF, I redfacedly admitted:

http://www.oldrocketforum.com/showpost.php?p=60409&postcount=87

(...that I'd come up with a few designs, despite my reluctance to take Craig's challenge to release one new design a week for a year.) Those include:

Nov. 02 -- XPL Experimental
Nov. 09 -- Doc Boy
Nov. 16 -- 5820 A
Nov. 23 -- 5820 B
Nov. 30 -- 5820 C
Dec. 07 -- 5820 D
Dec. 14 -- 5820 Ugly
Dec. 21 -- SONAR 7
Dec. 28 -- Premonition
Jan. 04 -- Epsilon 3
Jan. 11 -- 1.36X Estes Scamp
Jan. 18 -- 1.68X Estes Scamp
Jan. 25 -- Argent


I just updated the list to include designs released since then:

Feb. 02 -- 1.37X Centuri Javelin
Feb. 09 -- 1.37X Centuri Akela-1
Feb. 16 -- 0.44X Centuri Littler Hustler
Feb. 23 -- 0.56X Centuri Aero-Dart
Mar. 02 -- En Garde (BARCLONE Design #600) :D :cool:
Mar. 09 -- Roguish Lee
Mar. 16 -- Phobos V ("Five") 13mm
Mar. 23 -- Phobos V ("Five") 18mm
Mar. 30 -- Seeker P-S
Apr. 06 -- Azteca
Apr. 13 -- Perpetrator
Apr. 20 -- Prometheus 13mm
Apr. 27 -- Vaquero

Oddly enough, that adds up to two lists of 13 each... which means that I'm halfway through a 52-week year.

(I tend to make lists so I remember to do the stuff that's on them. :o Plus I have to keep all my facts straight in my day job. ;) So this list is just to see if I can pull off Craig's challenge or not. :rolleyes: )

Anybody else bothering to be this anal-retentive? :eek: --Probably not. (I didn't think so.)


Cheers,

CPMcGraw
03-23-2009, 12:36 PM
...Anybody else bothering to be this anal-retentive? :eek: --Probably not. (I didn't think so.)...

Well, probably not, but your contributions to the cause are always appreciated. I tend to release designs in bursts, with some occasional gaps (like the one I'm in right now). So I'm not keeping close track of my ratio.

mycrofte
03-23-2009, 12:39 PM
Would it help if I sent my designs to you? As posted elsewhere, according to RockSim 8, they need tweaking...

CPMcGraw
03-23-2009, 04:07 PM
Would it help if I sent my designs to you? As posted elsewhere, according to RockSim 8, they need tweaking...

If you already have them in RS8 format, why not post them here in the "Designer's Studio" section? Follow the "general" pattern that you've seen us use, and you'll do fine. One thing that I often repeat is to watch your launch rod length requirement, and what the deployment velocities are for each engine you select. If there are any issues with the design, we'll chime in and walk you through them, showing you whatever might need tweaking.

Join the group! We can use all the talent available!

mycrofte
03-23-2009, 05:19 PM
Well, I haven't even got that far with RockSim yet. I'm still trying to make an odd fin rocket stable. That is why I was hoping you guys could help. (a.k.a fix it for me...)

http://www.angelfire.com/il2/mycrofte/cgi-bin/Andromeda_01.rkt

I haven't figured out how to do some of the stuff here. I'll try this link to my RockSim 8 file.

CPMcGraw
03-23-2009, 08:51 PM
I'm looking at the Ascendant now. I'll try to post something shortly...

CPMcGraw
03-23-2009, 09:31 PM
Here is the design submitted by mycrofte, with just a few revisions. I'll outline them here:


Modified fin shape -- Made the openings in the fin larger, which reduced weight and put the larger surface area to the rear. The design was marginally stable with the original fins.
Scaled the fins down -- Reduced the overall size of the fins to 75% of the original outline. This by itself improved the stability margin.
SEMROC components -- Just a force of habit... :D
Lengthened stuffer tube
Added one centering ring
Used the Quest C6-5 instead of the Estes C6-5 -- Slightly better Dv


Length: 22.76"
Diameter: 1.32" (ST-13)
Fin Span: 4.72"
Weight: 2.1 oz

Launch Rod: 36" x 1/8"


B4-4.......343'......Dv 7 FPS
B6-4.......353'......Dv 3 FPS
C6-5Q......881'......Dv 19 FPS



Enjoy!

Thanks, mycrofte, for sending this in. Keep plugging away at RockSim, even if all you have is RS8. Those of us with RS9 can still read those files, and there are a lot of folks who also don't have RS9. It took a lot of practice for any of us to understand this program, and it still surprises us every so often. So don't be discouraged with your results right now, you'll get there soon enough! You'll be creating designs in your sleep before long, and then you'll never get any sleep! Welcome to our asylum, mycrofte! "You can check out any time you like, but you can never leave!"

Tau Zero
03-23-2009, 09:58 PM
mycrofte,

As Craig has already said, "Welcome to the asylum!" :eek: ;) :D

(chuckling) This reminds me of *my* early days with RockSim. (Gee, was it only 4 years ago? :o )


Here are my suggestions.

1) Use the RockSim simulation settings instead of Barrowman.

2) For this design, select the "nose cone base diameter."

3) Change the body tube material from "paper" to "spiral/glassine." (An error in the database.)

4) Change your fin material from polystyrene to balsa. 3/32" thick translates to 0.0938" T. You want most of the weight of your rocket (CG) toward the nose.

5) Make the base of the engine mount at least even with the base of your outer tube, instead of recessing it.

6) With the fins this big, I had to add *two* SE-14 screw eyes to the base of the nose cone.

7) Oh, I almost forgot! I added some birch dowel detailing toward the front end of the main body tube to add some more weight "up front."

8) Is the parachute *really* that heavy? The descent rate is kind of slow, which leads to drifting. You could probably reduce the diameter to 14" or so. An "average" descent rate would be about 12 fps.


Don't be overwhelmed by all these details! All of us found this out by sheer trial and error (and mutual nudges in the ribs).

Now, take all of the stuff that you heard here, and blow us all away with your new designs! :D

.

CPMcGraw
03-24-2009, 12:04 AM
And always remember to match your components, which is what I forgot to do with my revision... :D

Jay, strange as it may sound, the Barrowmans beat the RockSim in stability with this design. See my revision for the sad story...

mycrofte
03-24-2009, 03:53 AM
Thanks for the help guys! And I don't think the engine tube was recessed. It just keeps loading that way. I figured it was a 'flaw in the matrix'.

As for the chute, I went with what seemed to be standard for this size rocket.

When I started I was wanting something like the Sunward "INTERPLANETARY SHUTTLE". But I could never get it close to stable at that short a length. I tried loading someone's RockSim file but it crashed. So, I figured it was a Ver. 9 file with new stuff in it.

CPMcGraw
03-24-2009, 12:36 PM
Thanks for the help guys! And I don't think the engine tube was recessed. It just keeps loading that way. I figured it was a 'flaw in the matrix'.

As for the chute, I went with what seemed to be standard for this size rocket.

When I started I was wanting something like the Sunward "INTERPLANETARY SHUTTLE". But I could never get it close to stable at that short a length. I tried loading someone's RockSim file but it crashed. So, I figured it was a Ver. 9 file with new stuff in it.

For the engine tube, check to see if it is referenced to the rear of the main body tube, and not the front. That way, if you change the length of the main tube, the engine tube remains in its correct position. On my revision of your plan, I think I referenced the engine tube to the rear of the body, so it should stay even with the back edge.

If that file you looked at contained pods, then yes, it will crash in Ver. 8. That's the bad thing about our changing to Ver. 9, you absolutely have to have Ver. 9 to read them. Apogee is supposed to be posting the demo of Ver. 9 at some point, but I don't think they've done it yet.