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  #81  
Old 08-10-2008, 10:03 PM
Carl@Semroc's Avatar
Carl@Semroc Carl@Semroc is offline
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Carl McLawhorn
NAR#4717 L2
semroc.com
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  #82  
Old 08-10-2008, 10:06 PM
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moonzero2 moonzero2 is offline
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Quote:
Originally Posted by Carl@Semroc
If you drill the nose cone deep enough to install 1/2 to 3/4 oz weight, the washer is not necessary. It is far too low at the base of the nose cone, anyway!

Extending the engine farther back will require slightly more weight, since that also moves the CG backward. The K-22 V-2 is so small for the weight of the engine, it is very hard to balance it with the scale fins. I don't know how it ever was stable back then.

For scale fins with a 2.5" deep 1/2" hole filled with lead weigh and C6-5 enginet:

.5 oz weight and no overhang .25 calibers
.5 oz weight and .25" overhang .16 calibers

.75 oz weight and .25" overhang .50 calibers

Just the included weight and screw eye and no overhang - minus .52 calibers!!

vs.

Semi-scale fins with included screw eye and weight .25" overhang - plus .5 calibers.

Now that is some real "Rocket Science".
Thanks Carl
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  #83  
Old 08-11-2008, 08:14 AM
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JRThro JRThro is offline
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Quote:
Originally Posted by Carl@Semroc
For scale fins with a 2.5" deep 1/2" hole filled with lead weigh and C6-5 enginet:

.5 oz weight and no overhang .25 calibers
.5 oz weight and .25" overhang .16 calibers
.75 oz weight and .25" overhang .50 calibers

Just the included weight and screw eye and no overhang - minus .52 calibers!!

vs.

Semi-scale fins with included screw eye and weight .25" overhang - plus .5 calibers.

That's great info, Carl.

What's the stability with semi-scale fins with included screw eye and weight and no overhang? That's how I built mine, though if I ever get the motor out I'm going to glue in a second motor block so there will be 0.25" overhang for any future flights.
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  #84  
Old 09-18-2008, 07:52 PM
Initiator001 Initiator001 is offline
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I finished my Semroc Mark xKit last week.

I decided to find my original 1970 vintage Estes Astron Mark and photograph the two, side-by-side.

I still have the instruction sheet for the Astron Mark in my files.

Bob
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