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  #11  
Old 07-31-2022, 09:13 PM
frognbuff frognbuff is offline
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Just a simple model - but let's see if she can fly!

If it works, I may make more effort to replicate the fin shapes, pitot tubes etc. But the 3D printed parts are good to go, should I need to build another!
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  #12  
Old 07-31-2022, 09:27 PM
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Ez2cDave Ez2cDave is offline
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Quote:
Originally Posted by frognbuff
Just a simple model - but let's see if she can fly!

If it works, I may make more effort to replicate the fin shapes, pitot tubes etc. But the 3D printed parts are good to go, should I need to build another!


Very cool !

What size is that model ?

There is nothing in the photo to use as a "reference", for size.

Dave F.

Last edited by Ez2cDave : 07-31-2022 at 09:53 PM.
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  #13  
Old 08-01-2022, 06:02 AM
frognbuff frognbuff is offline
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Quote:
Originally Posted by Ez2cDave
Very cool !

What size is that model ?

There is nothing in the photo to use as a "reference", for size.

Dave F.


BT-60 booster, BT-50 sustainer. Over 2' long in total. I'll take another pic with something to provide scale.
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  #14  
Old 08-01-2022, 11:32 AM
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Ez2cDave Ez2cDave is offline
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Quote:
Originally Posted by frognbuff
BT-60 booster, BT-50 sustainer. Over 2' long in total. I'll take another pic with something to provide scale.


18mm or 24mm motor ?

Dave F.
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  #15  
Old 08-01-2022, 09:21 PM
frognbuff frognbuff is offline
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Definitely 18mm. That nozzle is integral to the model (remember, the fins attach to the nozzle) and an 18mm tube just barely fit.

That is the standard Der Red Max model.
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  #16  
Old 08-01-2022, 11:10 PM
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Quote:
Originally Posted by frognbuff
Definitely 18mm. That nozzle is integral to the model (remember, the fins attach to the nozzle) and an 18mm tube just barely fit.

That is the standard Der Red Max model.


Much better with something to give it scale !

Where is the CP located ?

Dave F.
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  #17  
Old 08-02-2022, 06:10 AM
frognbuff frognbuff is offline
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Haven't modeled in RockSim yet. So I'm not sure. For now it has a bunch of nose weight and room for more if needed.
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  #18  
Old 08-02-2022, 08:41 PM
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Quote:
Originally Posted by frognbuff
Haven't modeled in RockSim yet. So I'm not sure. For now it has a bunch of nose weight and room for more if needed.

"Eyeballing" it, I think the CP is about 3/4" - 1" below the "Star" decal.

Dave F.
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  #19  
Old 08-03-2022, 06:01 AM
frognbuff frognbuff is offline
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Quote:
Originally Posted by Ez2cDave
"Eyeballing" it, I think the CP is about 3/4" - 1" below the "Star" decal.

Dave F.


That would be fantastic. CG will well forward of that point!
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  #20  
Old 08-03-2022, 09:33 AM
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Quote:
Originally Posted by frognbuff
That would be fantastic. CG will well forward of that point!


Be SURE to calculate the CP !

The "Cardboard Cutout" method is very conservative and 99% of the time, provides a safe CP location.

I you want to calculate the CP manually ( and don't want to struggle with the Barrowman Equations ), Bruce Lee simplified the process, about 25 years ago ( below ).

Dave F.
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