From: <Roger.Wilfong@umich.edu>  (Roger Wilfong)
Subject: Re: More NCR Problems
Organization: UofM Hospitals
Date: Mon, 12 Oct 1992 14:03:00 GMT

In Article <12OCT199208114754@vx.cis.umn.edu> "soc1070                         " says:
> Yesterday out at the flying field, one of our members brought out the 
> latest offering from North Coast Rocketry - one of the new plastic cones.
> 
> This cone was pathetic! Oh, the plastic itself was ok - but the 
> dimensions were way off! The cone was the NC-26P, designed for their
> 2.7 inch O.D. tube. The section of the cone that is supposed to slide
> into the tube was way too small, off by .130! Dale, the guy who bought
> the cone, found out by accident that the cone fits really well into
> the STAGE COUPLER (!). But, after thinking he may be able to save this
> cone, Dale discovered that the diameter of the shoulder is off-center
> by almost .063 (1/16) inch.
> 
> Needless to say, he is sending it back. I don't think NCR is going to 
> be able to blame this one on differences in humidity between their
> location and ours!
> 
 
It sounds like I;m walking in in the middle of some long standing beef with 
NCR.  My experience with the NC-26 nose cones are as follows:
 
NCR's BT-26 (2.7" OD) tubing is different from the 'standard' 2.6 tubing sold
by everybody else.  NCR started with some nose cone molds and bought tubing 
to fit.  Chris Pearson (or somebody else in Cleveland) used to mold each and
every Aerofoam cone until the price of the raw materials and production 
nearly quadrupled and the Aerofoam cones became too costly to be competitive.
At that point (last year), NCR switched to ACE, LOC and Aerotech blow molded 
nose cones where equivalent sizes were available - where they weren't, they
discontinued or modified the kits.
  
That was fine for BT-18 (Aerotech nose cone) and BT-39 (LOC and ACE nose 
cones); however, it is a problem for the BT-26 rockets.  As noted above, 
BT-26 is different - its ID is the same as everbody else's OD in this tube 
size.  As a result, the you need a stage coupler to make an LOC or Aerotech
cone fit a piece of BT-26.  
   
My Lance Beta came with an Aerotech cone instead of the Aerofoam cone.  
Included were two stage couplers, one for the seperation point and one as an 
adapter for the nose cone.  Included was a note about how to install the cone 
and adapter.  It works fine.  There is a slight OD mismatch between the BT-26
and the cone (the cone is smaller), but it is no greater that the mismatch 
between the Aerotech nose cone and the Aerotech tube in my Initiator (the 
cone is larger).
  
If the cone was manufactured with an off center shoulder, I'm sure NCR will
replace it - my experience (the UPS truck must have run over the shipping 
box) with NCR is that they are very prompt in fixing anything that's wrong.
   
I for one miss the Aerofoam cones.  They did require different care in 
finishing them and needed a dowel to strengthen the shoulder/cone joint.  But
they supplied a different shape (and additional sizes) from the 'standard' 
cones (the Corporal sport scale model was reasonably close with the NC-18
Aerofoam cone - it's hideously wrong with the Areotech cone).