[roc-chat] Re: Stability of a rocket with strap-on boosters

I entered the info into Rocksim 9 for my Delta X rocket that had 4 strap-ons.  
However, I wasn't able to eject the strap-ons during the simulation.  
Evidently, there's a trick I don't know for how to do this.  Anyway, the mass 
of the engines in the strap-ons seemed to bring the CG back more than the CP.  
I added additional weight to the Delta X to bring the CG forward and I don't 
want to add a bunch of extra weight to the Delta II.
 Richard > Subject: [roc-chat] Re: Stability of a rocket with strap-on boosters
> From: allen.farrington@xxxxxx
> Date: Wed, 10 Aug 2011 11:33:33 -0700
> To: roc-chat@xxxxxxxxxxxxx
> 
> Rocksim 9 has tools built-in to model strap-on boosters. If you have Rocksim 
> 7 or 8, there are ways to trick it into simulating them.
> 
> Allen
> --------------------------------------------------------------------
> Allen H. Farrington
> 818-653-2284
> web: http://www.allenfarrington.org
> 
> On Aug 10, 2011, at 11:29 AM, Kurt Gugisberg wrote:
> 
> > Richard,
> > 
> > The strap-ons will add some drag stability (base drag) as well as an area 
> > equivalent to fins or a larger airframe area.  Knowing just how to factor 
> > that in is the tricky part.  I think you can fudge it into rocsim somehow.
> > 
> > Kurt
> > -----Original Message----- 
> > From: Richard Dierking 
> > Sent: Aug 10, 2011 10:34 AM 
> > To: roc-chat@xxxxxxxxxxxxx 
> > Subject: [roc-chat] Stability of a rocket with strap-on boosters 
> > 
> > I'm considering the size and shape of the 3 fins for my Delta II 7925-10L.  
> > It's a 4" core transition to 5" on top with 9 strap-ons, each approximately 
> > 1.5" dia (BT-60 tube).  total height is 65".  I don't want it to be a 
> > high-velocity rocket and I'll be using a J135 for the core, six F-30's 
> > strap-ons 0.5 sec after launch, shed those, then airstart three G's 
> > strap-ons then shed the last three strap-ons. 
> >  
> > For the 3 fins, I'm using 3/16" thick abrasion resistant polycarbonate that 
> > by my estimate has a stiffness similar to 1/8" birch.  The fins are 
> > through-the-wall and fiberglassed to the 54mm engine mount.  I'm thinking 
> > to configure the fins as clipped deltas to avoid busting a tip during 
> > landing.  Since the rocket has 9 strap-ons, seems to me this would add 
> > stability during launch (like tube fins).  Am I wrong thinking this?  I 
> > would like to keep the fins on the small size.
> >  
> > Please advise and thank you,
> > Richard Dierking
> >  
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> 
> 
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