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8.2.8.1 How do I attach a pop pod to a glider?




Description

This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.

8.2.8.1 How do I attach a pop pod to a glider?

Some sort of positive hook is needed, yet it must be designed
to separate easily at ejection. Once common method is the
"Piece X" or xerclod hook, where a rhombus hook is cut from
the fuselage and attached to the pop pod. Use a razor saw for
most of this cutting. The fuselage is then sheathed with thin
balsa or plywood around the notch. This creates a weak spot in
the fuselage where it can break, especially during trimming.

I prefer to cut the Piece X from the pop pod and glue it to the fuselage:

	_________________________________________
	~		pop pod body tube	|
	_________________________________________
	    		\	  pylon		\
			 \       _________       \      sheath pylon with 1/64 plywood
			  \     / cutout /	  \     extend below pylon to overlap
			   \___/	/__________\    1/4" of fuselage for alignment

				 ________
				/piece X/
			_______/_______/__________________________________
			\
			 \      Fuselage forward end
			  \
			   \___________________________________________________

A common mistake is to have the pylon grain, be it pop pod,
fixed pod, or other design run parallel to the fuselage. It
results from cutting the pylon from the same stick as the
fuselage. DON'T! This is bad for the same reason you don't
have the fin grain run this way, it can easily break off. For
maximum strength, both the pylon and the piece X should have
their grain running parallel to their leading edge. That
requires discarding the piece X cut from the pylon, and
cutting out a new one, regardless of whether you cut the X
from the pylon or the fuselage. An acceptable compromise is to
have the grain run perpendicular to the fuselage, so the piece
X is usable.

	\-------------------------------\
	 \				 \
	  \...............................\	BAD
	   \				   \
	    \-------------------------------\
 
	\-------------------------------\
	 \	:	:	:	:\
	  \     :       :       :       : \	Better
	   \	:	:	:	:  \
	    \-------------------------------\
 
	\-------------------------------\
	 \   \   \   \   \   \   \   \   \
	  \   \   \   \   \   \   \   \   \	BEST!
	   \   \   \   \   \   \   \   \   \
	    \-------------------------------\

Other attachment methods use a dowel or pin, external hooks of
thin plywood glued to the outside of the pod/fuselage, nested
square brass tubing (see

 

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previous page: 8.2.8 Can I convert a hand launched glider (HLG) to rocket power?
  
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next page: 8.2.9 I'd like to design my own glider. How do I know if it will work? How do I compute the CP for a glider?