[roc-chat] Re: Stability: Time to Use the Mojo
- From: Richard Dierking <redierking@xxxxxxxxxxx>
- To: <roc-chat@xxxxxxxxxxxxx>
- Date: Fri, 19 Aug 2011 00:29:02 +0000
Nice one Jack! :) Yes, something like a K1275R would peel the strap-ons off
nicely. I would probably never see them again, but they would come off.
Richard From: jackgaribaldi@xxxxxxx
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Stability: Time to Use the Mojo
Date: Thu, 18 Aug 2011 17:23:42 -0700
Put a K in that mother and the booster will come off automatically
LOL!!!!!!!!!!!!!! Jack G From: roc-chat-bounce@xxxxxxxxxxxxx
[mailto:roc-chat-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Dierking
Sent: Thursday, August 18, 2011 5:09 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Stability: Time to Use the Mojo Thank you for this
offer, and I apologize for the delay in my reply. I'm continuing to work on
the Delta II and will be entering info into Rocksim 9 in a couple weeks. I
have the Delta X file that had a 4" dia core and 4 strap-ons of the same dia,
so I'm just going to modify this data for the sim.
I'll post how the build is going and perhaps bring the rocket under
construction to the Sept launch.
Thanks again for all the help,
Richard Dierking Date: Fri, 12 Aug 2011 11:25:12 -0700
From: indanapt@xxxxxxxxx
Subject: [roc-chat] Re: Stability: Time to Use the Mojo
To: roc-chat@xxxxxxxxxxxxxxx you'd like I can punch the numbers into ROCKSIM
with and without shadowing. I just need the basic dimensions to get you a CP
(not CG but CP). Just ask. ---------------------------------------
Jeff Gortatowsky, Redondo Beach, CA | Twitter: JeffGortatowsky | Yahoo:
indanapt "(Scientific) Skepticism is not a set of beliefs, it is a set of
methods for asking questions about reality." -- Doctor Steven NovellaFrom:
Richard Dierking <redierking@xxxxxxxxxxx>
To: roc-chat@xxxxxxxxxxxxx
Sent: Thursday, August 11, 2011 8:36 AM
Subject: [roc-chat] Re: Stability: Time to Use the MojoNot at all; very good
question. I considered this. I wanted to keep the fin number down to a
minimum because the strap-ons are ejected (with pyro bolts) and I don't want
them hitting the fins. The first six strap-ons that are ejected are on
opposite sides of each fin. This will leave the last three airstarted
strap-ons centered between the three fins and should help to provide fin area
for the correcting force during the last part of powered flight.
Richard Date: Wed, 10 Aug 2011 21:01:58 -0700
Subject: [roc-chat] Re: Stability: Time to Use the Mojo
From: rubr.duky@xxxxxxxxx
To: roc-chat@xxxxxxxxxxxxx
Silly question... Why not six?On Wed, Aug 10, 2011 at 20:46, Richard Dierking
<redierking@xxxxxxxxxxx> wrote:Thank you! After reading the first couple of
replies I was beating my head against my desk and saying "why did I make the
fins pink and blue!" and "why did I ask those guys!" I did appreciate the
humor.
If I showed the rocket core without the strap-ons (I'll use different colored
paper next time), you might say the blue fins are large enough. But, the
strap-ons hide the size. For one side, the pink fin is 120 cm^2 and the blue
fin is 90 cm^2. So, the pink fin has about 25% more surface area but only
sticks-out 3/4" more. 4" Goblin fins have about 85 cm^2 per side There are 4
fins on a Goblin and I usually build with 4 fins. I can't do that with a 9
strap-on configuration.
As usual, as the mass of the solid engines is consumed, the CG will move
forward. But, the strap-ons will shed during the flight and change the CP and
keep in mind that each of the core fins are between strap-ons that will be
released during powered flight. This really complicates things.
I thought about adding fins to the strap-ons but this creates some additional
problems like re-contact after deployment and the possible roll force on the
attachment points.
(one hour later...)
I'm going to use the pink-sized fins.
Thank you, and I'm going to blame all of you if the rocket's overstable or I
become unstable. :)
Richard > Subject: [roc-chat] Re: Stability: Time to Use the Mojo
> From: allen.farrington@xxxxxx
> Date: Wed, 10 Aug 2011 13:49:29 -0700
> To: roc-chat@xxxxxxxxxxxxx
> > Pink, definitely. You know, how big should they be if the pods had no CP
> > effect, but still have the mass? I think that they look small.
>
> Allen
> --------------------------------------------------------------------
> Allen H. Farrington
> 818-653-2284
> web: http://www.allenfarrington.org
>
> On Aug 10, 2011, at 12:58 PM, Richard Dierking wrote:
>
> > When you're working on something like this Delta II you start to develop
> > mind roll. I realized that I need to make a decision on the fins before I
> > become a really old man.
> >
> > So, please look at the two photos showing a blue and pink fin. There will
> > be 3 fins and they will be transparent and the rocket's about 6' tall. As
> > Barney would say, "time to use our imagination..." Please provide your vote.
> >
> > Thank you. I'm going off to do something simple like work.
> >
> > Richard
> > <bluefin.jpg><pinkfin.jpg>
>
>
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