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Estes Mini Bertha

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kuririn

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Dudley,
The fin template is on the SP-TK3 pattern sheet with the plans linked to in post #2.
As Steve mentioned use the part #s from the parts list in the plans to get the parts from erockets.
For example the nose cone is part # BNC-20L. Go to erockets and scroll down the left hand menu to Parts for rockets/Nose cones/BNC-20. Scroll down the main field till you find the BNC-20L nose cone.
Do the same with the other parts.
Note: the 18mm Mini Bertha has a 13mm (BT-5) motor mount.
Just FYI.
 

Dudley

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Are the eRockets "Mini-Bertha" fins correct for the BT-5 or BT-20?
I bought them and they look much too small for the BT-20.
As to the fin template, I must be doing something wrong... when I print the page the template (again) seems much too small for a BT-20; like the image has been compressed or something. Than you for your patience with me. I'm about to hit the abort button on this project...
 

stantonjtroy

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After doing more research, I think I understand my confusion... the plans I have are for an 18mm (BT-20) "Mini Bertha".
The BT-5 version a lot of guys seem to be building is a "downscale" version.
Correct. Many are downscaling to a BT-5 airframe for Micro Motors. The original kit is a BT-20 airframe w/ a BT-5 motor mount. As for the template print out..... look at your print settings and make sure the "Scaling" is set to 100% and not something like "Fit Page".
 

Mightymango

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They should be around 1 x 3 roughly in size for the fins. The ones from erockets for the balsa SEM-FES-0803 are the correct fins as that is what I ordered for mine and they look correct.

The fin template on Jimz has a 1inch scale in the corners if you need a size reference.

Also use the PDF as that typically will have the scale correct

 
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