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View Full Version : Astron Cobra fin pattern, anyone?


Quasar
01-24-2009, 09:15 PM
I'm getting ready to start on an Astron Cobra clone, but after looking through my collected documentation, I've found three fin patterns that are all different. Does anyone have an original pattern that they can scan and share with the rest of us? Even measurements of an original pattern would work. Thanks.

LeeR
01-24-2009, 10:04 PM
I'm getting ready to start on an Astron Cobra clone, but after looking through my collected documentation, I've found three fin patterns that are all different. Does anyone have an original pattern that they can scan and share with the rest of us? Even measurements of an original pattern would work. Thanks.

Quasar,

I built a Cobra last summer, and you are right, the fin patterns differ. I used the one that was from the Astron Cobra plans in Model Rocket News. I do not recall if it was larger or smaller than the fin pattern in the kit. I just decided that was the one I wanted to build, and technically, this would be the original, since it appeared prior to the kit.

On JimZ site, the Cobra plans also include Peter Alway's Cobra drawing and fin pattern.

If you want the one page plan from MRN, I can email it to you, just PM me.

Here is a picture of mine. I used a threaded insert to hold a 4-40 screw with washer (not shown), rather than engine hooks. I wanted the original look, but didn't want to rely on tape for motor retention. This insert is a clevis used on RC servos, with the wings clipped off, leaving just the threaded tube. On display, you do not see the threaded insert, it is flush with the motor tubes.

http://i265.photobucket.com/albums/ii220/hobbes_pics/Astron%20Cobra/th_cobra008.jpg (http://s265.photobucket.com/albums/ii220/hobbes_pics/Astron%20Cobra/?action=view&current=cobra008.jpg)
http://i265.photobucket.com/albums/ii220/hobbes_pics/Astron%20Cobra/th_cobra.jpg (http://s265.photobucket.com/albums/ii220/hobbes_pics/Astron%20Cobra/?action=view&current=cobra.jpg)

johnnwwa
01-25-2009, 12:23 AM
The fin set you need are at SEMROC for the cobra:

hereis the link.

http://www.semroc.com/Store/scripts/ClassicParts.asp?ID=11


John

mojo1986
01-25-2009, 07:44 AM
Mike..............I have an older fin pattern here. Rather than scan it I'll just provide measurements:

Root Edge..................2 3/4"
Leading Edge.............6 13/16"
Trailing Edge.............3 11/16"
Outer Edge................1 5/8"

Joe

Quasar
01-25-2009, 04:11 PM
Hi, Lee,

PM sent. Thanks.

Quasar
01-25-2009, 04:29 PM
The fin set you need are at SEMROC for the cobra:

hereis the link.

http://www.semroc.com/Store/scripts/ClassicParts.asp?ID=11


John

Thanks for the reply, John. I checked it out, but be aware there's an error on that page. The fins listed are actually for the WAC Corporal, but if you do a search for FES-K10, they show up and can then be added to the Shopping Cart. I'll try to send Carl an email about that. Thanks.

Quasar
01-25-2009, 04:30 PM
Mike..............I have an older fin pattern here. Rather than scan it I'll just provide measurements:

Root Edge..................2 3/4"
Leading Edge.............6 13/16"
Trailing Edge.............3 11/16"
Outer Edge................1 5/8"

Joe

Hey, Joe!

Thanks! That really helps.