Estes PNC-20A

[Fore Check]

So I'm cooking up another project here, and I come across PNC-20A in the plans. It looks like an ogive cone in the neighborhood of 3 or 4 : 1.

I checked the ninfinger chart, and an old catalog, and the only reference they have of a 20A cone is a balsa cone that's roughly the shrunk down equivalent of a Big Bertha or Fat Boy cone (short and elliptical.)



Does anyone out there know the length of the plastic nc 20A????

 

[Fore Check]

Nevermind - I figured out a different way to get the answer I was looking for.




Don't mind me, I'm just having conversations with myself. Do it all the time.

 

[powderburner]

I thought Estes only substituted materials, but kept the same geometry. Is that not true?

As far as "Don't mind me, I'm just having conversations with myself. Do it all the time." goes, at least you are only talking to yourself. Half the time, I put stuff down (someplace) and then can't remember two seconds later where I set it or what it was that I was doing.

 

[Fore Check]

I thought the geometry was the same too, but apparently not.

According to the Ninfinger chart, the BNC 20A is a little domed cone that's 0.813" long above the shoulder.

According to my scaled measurements, the PNC 20A in the plans I'm looking at is an ogive cone that's 2.5" long above the shoulder.

 

[BobH48]

The PNC-20A was the cone used on the Mini-Patriot.

I just went and measured mine and it was 2.875" from the shoulder.

The BNC-20N that I got from BMS is almost exactly the same shape but is 2.75" from the shoulder.