Heavy Duty BT-50 Tubing!

Anybody who has followed the blog knows I hate BT-20 and BT-50 tubes.
They are thin walled and can crimp when friction fitting engines or on a hard landing.

The inside diameter of a Estes style BT-50 is .950". The wall thickness is .013".
The inside diameter of a Centuri style ST-9 is also .950". But, the wall thickness is .024".

Here's the highly scientific "squeeze test".
The BT-50 is on the left, the ST-9 is on the right.

This isn't a true test but you can easily feel the difference between the two tubes. The ST-9 is stronger.

On the left is the standard Estes Alpha nosecone, the BNC-50K.
The shoulder lip is low.

The other nose cone is a BC-928. It's made to match the profile of the BNC-50K nose cone.
The shoulder lip is wider to fit the thicker walled ST-9.
Both nose cones are from Semroc.




Here's the same nose cones in their matching tubes, BT-50 on the left, ST-9 on the right.
Not much difference visually but the model on the right is much stronger.
The great thing is, regular 20/50 engine mounts will fit this ST-9 tube.

A purist could argue it's not a real Alpha unless a BT-50 is used.
I really don't care.