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  #1  
Old 09-04-2018, 09:09 AM
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Default K-25 Alpha question.

I'm replicating the K-25 as it appeared in the 1974 catalog. The question is: where does the launch lug go in relation to the end of the BT50? I studied the instructions until my eyes bled but couldn't find the dimension.

Thanks!
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Old 09-04-2018, 09:30 AM
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There is no dimension. The instructions just say to glue the launch lug between the fins as per the fin marking guide which means, centered between two of the fins. The drawing shows about where to place the launch lug. You don't need a dimension.
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Old 09-04-2018, 10:24 AM
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Agree as well; there is no defined measurement of "XX" from bottom of tube in English or metric dimensions.
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Old 09-04-2018, 12:14 PM
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A dimension for locating the launch lug first shows up in revision C of the instructions - which is the version that introduced die cut fins, approximately 1980. The dimension given is 1 3/4 inches from the bottom of the body tube to the bottom of the launch lug.

This is the dimension I use when I clone earlier versions of the Alpha...as it certainly matches the description in the earlier versions of the instructions and it looks about right.
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Old 09-04-2018, 12:25 PM
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Perfect! Thank you all.

VR, Jeff
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  #6  
Old 09-04-2018, 01:18 PM
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Quote:
Originally Posted by BEC
A dimension for locating the launch lug first shows up in revision C of the instructions - which is the version that introduced die cut fins, approximately 1980.

So.... this dimension would not be for the K-25 Alpha as requested by the OP.
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Old 09-04-2018, 01:37 PM
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Does this help?
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Old 09-04-2018, 03:19 PM
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Quote:
Originally Posted by astronwolf
So.... this dimension would not be for the K-25 Alpha as requested by the OP.


Correct. As you and GH have noted, there is no dimension given on the instructions for the pre #1225 versions. But as I say, the dimension is consistent with the words in the K-25 instructions and it looks right located per that dimension.

If you entered a pre-1980 Alpha in Classic Model and I was judging, I couldn’t deduct from your outline score if your launch lug wasn’t 1.75 inches from the bottom of the body tube....or if you did
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Old 09-04-2018, 04:38 PM
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Quote:
Originally Posted by BEC
If you entered a pre-1980 Alpha in Classic Model and I was judging, I couldn’t deduct from your outline score if your launch lug wasn’t 1.75 inches from the bottom of the body tube....or if you did

God help anyone who enters a pre-1980 Alpha in Classic Model.

Even more to the point - the instructions state that the launch lug is glued between two fins, as per the fin alignment guide, but which two fins?
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Old 09-04-2018, 06:40 PM
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Quote:
Originally Posted by astronwolf
Even more to the point - the instructions state that the launch lug is glued between two fins, as per the fin alignment guide, but which two fins?

My overly technical, and artificially precise reading of step 7 says that the lug would be between the first and second fin that you glue on. Not the second and third, or third and first. If it's between the third and fourth fin, then you might be cloning the wrong kit. The first fin to attach is exactly 120 degrees from the motor clip, taking the thickness of the clip and the fin into account. Be sure to read between the lines in step 7 to determine whether the fins should have been assembled in a clockwise or counter-clockwise (or anti-clockwise to our UK friends) direction. Be sure to provide photographic evidence using a Brownie camera, or some other instamatic that was available in the day.

Also, although fin alignment guides help immensely, they didn't exist in the early years. So, I would guess that the build log should include the college-ruled paper with a hand-drawn circle and three fins sticking out which was used to visually align the fins.
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