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  #11  
Old 07-08-2012, 11:12 PM
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Quote:
Originally Posted by Carl@Semroc
The Goonies and Groonies are all "short, squat" designs that somehow get "aerodynamic exemptions" from the one caliber rule. I have heard of people changing the engine mount in the old Goonies from 13mm to 18mm, not adding nose weight and having stable flights. Rocksim shows that to be impossible.
That's while I'll be flight testing the latest riff on my Prometheus design. It's at 1.70 calibers empty, and 0.94 marginal on a C6-5. (crossing fingers)
.
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  #12  
Old 07-09-2012, 11:57 AM
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Since I know that OpenRocket does not know how to deal with Tube Fins (Yet), and this rocket has two of them (The rings), it will give a result a bit lower than expected for stability. That said, since it does not appear that adding .5 oz of nose weight will really hurt anything I may go ahead and do that. As you said, it was already a marginally stable design, and will depend somewhat on how well the rocket is built (i.e. any extra weight added to the tail).

Also, it's nice to have a good output from Open Rocket / RockSim with you just in case the RSO has any questions on the rocket.
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  #13  
Old 07-11-2012, 02:54 AM
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Quote:
Originally Posted by Carl@Semroc
The Goonies and Groonies are all "short, squat" designs that somehow get "aerodynamic exemptions" from the one caliber rule. I have heard of people changing the engine mount in the old Goonies from 13mm to 18mm, not adding nose weight and having stable flights. Rocksim shows that to be impossible.
I wonder if Rocksim would say that a bumblebee can't fly? :-)
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  #14  
Old 07-11-2012, 07:39 AM
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Reading through these posts, I begin to wonder just how accurate the mass/weight data is in the MATERIALS file...

Had to go back and look at the 1968 catalog page, and sure enough, it "recommends" the C6-5 as the upper-end engine.

RockSim is known to have trouble with RT calculations, so anything it reports concerning the Starlight needs to be examined with a pound of salt if you're using a ringtail component.
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  #15  
Old 07-11-2012, 09:43 AM
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Quote:
Originally Posted by CPMcGraw
Reading through these posts, I begin to wonder just how accurate the mass/weight data is in the MATERIALS file...
That's been one of my disappointments with Rocksim over the years. When upgrades would come out, it'd be a letdown to find the same, old support files with the same errors in them. One that comes to mind concerns the dimensions for BT-80. The ID is listed as 2.588" instead of 2.558".

The way the tool works, it calculates the mass based on the volume of paper (ie, circumference x thickness x length x density). With the ID wrong, the tube mass comes up very light (equivalent to about one wrap of kraft paper )

Not sure if this ever got fixed. (I'm running v7.1.)

Doug

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  #16  
Old 07-11-2012, 03:47 PM
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Quote:
Originally Posted by Doug Sams
That's been one of my disappointments with Rocksim over the years. When upgrades would come out, it'd be a letdown to find the same, old support files with the same errors in them. One that comes to mind concerns the dimensions for BT-80. The ID is listed as 2.588" instead of 2.558".

The way the tool works, it calculates the mass based on the volume of paper (ie, circumference x thickness x length x density). With the ID wrong, the tube mass comes up very light (equivalent to about one wrap of kraft paper )

Not sure if this ever got fixed. (I'm running v7.1.)

Doug

.

I'm running BSILG. I occasionally have problems, but I have yet to open a black hole that sucks all life into its maw.
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  #17  
Old 07-11-2012, 03:50 PM
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Quote:
Originally Posted by A Fish Named Wallyum
I'm running BSILG. I occasionally have problems, but I have yet to open a black hole that sucks all life into its maw.

BSILG?? Is that a knock off on TLAR?
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  #18  
Old 07-11-2012, 04:01 PM
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Quote:
Originally Posted by DaveR
BSILG?? Is that a knock off on TLAR?
I wondering the same thing, Dave. I think the ILG part means "it looks good".

Can't figure out the BS part, tho

Doug

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  #19  
Old 07-12-2012, 07:04 AM
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"Bill Says It Looks Good" ???
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  #20  
Old 07-12-2012, 08:20 AM
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Quote:
Originally Posted by Doug Sams
I wondering the same thing, Dave. I think the ILG part means "it looks good".

Can't figure out the BS part, tho

Doug

.

I was thinking the same thing on the ILG.
Maybe the BS is just that.

B S It Looks Good.
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