Centuri Argus #KB-9, Build, Part 3, Centering Rings

I used Centuri ST-7 for an engine mount tube. It's a little larger diameter than an Estes BT-20. The only engine blocks I have fit the BT-20.
I did two wraps of copy paper applied with a glue stick to fit the slightly wider tube.

I didn't know that the original kit had foam core centering rings. These were probably more robust than an regular centering ring at .050" thick.
The instructions say these rings are stronger and don't require a black coupler tube.

TRIVIA: Years back, all Estes and Centuri kits had black fish paper couplers between centering rings. Now most kits have just the two rings that center the engine tube in the larger tube.
If you ever tried to glue in one of these older style mounts, they would sometimes freeze in the wrong spot, not slid all the way into the main air frame tube! Maybe that's one reason they are no longer used in engine mounts. (That, and the vendor probably saves a nickel per kit.)




I'm making two Argus models so I needed to notch four rings for two engine mounts.

TIP: You can make the notch sizes consistent by stacking the rings and cutting with a sharp blade.