I realized recently that one of my cloning projects, the 1962 Centuri Aero-Dart (KF-2), calls for an aluminum launch lug. This is a heavy tube LT-150 craft from the F-power line (this first and only such kit that year), and the first of the many different Aero-Darts. The aluminum launch lugs were also sold separately in the F-power building supplies, available in 3/16" or 1/4" O.D. The aluminum LLs in kits seem to have only lasted a short time - by 1966 the 3rd generation Aero-Dart featured "fibre" launch lugs in its description.

So, anyone actually sourced and built in an aluminum LL? Did any other kits/lines of that era use them? I'm thinking my best current source might be a (drinking) straw, apparently right around 1/4" O.D. - though I think most metal straws are stainless steel.

Thanks.

http://www.ninfinger.org/rockets/ca...62/62cen18.html

Edited in better source of (hobby) tubes at Amazon

Yes! When I cloned the first two versions of the Aero-Dart, I used 3/16" tube for the lugs.

And balsa centering rings! With no motor retention. Surface mount fins with fabric reinforcing!

Old school.

P.S. The 3/16" aluminum tube was from a hobby store, as I recall.

Attached Thumbnails

       

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NAR #27085 - Oregon Rocketry - SAM

Nice. Yes, I am planning the fabric on fin method as well, as on 1 or 2 early Estes models. I'm not quite as faithful to the old school when it comes to internals though, like motor tube length, block, shock cord, etc. Silk parachutes are also tough.

Edit: The clones/pics look great! Could I trouble you (if handy) for your fin template (or any measurements) on the 1962 3-fin edition? Please and thank you. I just did a run through this morning, going from catalog pic, relative measurements based on what I think I know about BT diameter (1.59") and length (22"), NC (8"), to an Open Rocket fin design. My first stab has root and tip chords of 4.45", height 4.1", and sweep angle 45. But they look a little big so I'd love a 2nd opinion.

The imprecision and (catalog) angles and artistic license can unduly alter the outcome, I think. The 1964 catalog (4-fin + payload) edition that you posted is a good example. When I look at the fins in that picture, does it kind of look as if all 4 are on the back side of the rocket? Probably not, though.

The 1/8th inch aluminum launch lugs were available through Centuri through the 69-2 catalog. No later appearance of them, even in the Mini-Max section of the catalog in the various 1971 catalogs (711, 712, and 71D versions).

Attachment below from the 69-2 catalog.

Earl

Attached Files

Centuri 69-2 Catalog Page 55.pdf (855.0 KB, 16 views)

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Earl L. Cagle, Jr.
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Rocket-Brained Since 1970

I would be really surprised if those aluminum launch lugs were anything other than sections of aluminum tube from the K&S metals rack that most hobby shops used to have. I’m sure Centuri had access to that stuff in bulk. They were/are sold in nesting sizes, so I’d expect they would have picked the next size up from 3/16 or 1/4 (or even 1/8) so 7/32, 9/32 or 5/32 respectively. So, for example, this https://ksmetals.com/products/alt029-9-16 For 1/4 inch lugs.

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That sounds about right. When I went looking today I quickly found K+S and their thin-walled tubes met the specs in the old Centuri catalog very well. Centuri just cut them to length, added them to a few kits and sold them individually as well.

In the oldest of the Estes catalogs, which I checked to see what they were up to LL-wise in that same time frame, I found catalog copy to this effect: these are really just drinking straws, but we cut them up and sell them to modellers as a convenience.

Now, Mylar. There was a time, after the aluminums fell away, when Mylar LLs were featured/offered, including by Enerjet. I first imagined these to be transparent, like that early Streak tube. But maybe not, as it seems even modern launch lugs often are made with a Mylar core for strength, but with fiber/paper wrap etc. to facilitate gluing.

I posted fin templates for the two early Aero-Dart models . . . somewhere. Probably in Ye Olde Rocket Forum.

Please search around. If you can't find them, I'll scan them again, but they will take a while.

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NAR #27085 - Oregon Rocketry - SAM

Thanks, I'm sure I'll find them,

There was some small rocket company in 1970, can't recall the name, that used aluminum lugs for their kits. Those sucked because white glue/Titebond could not glue them, they came off easily.

I ended up using some contact cement on the lug, and on the original glue joint's perfectly fitting curved surface, to glue the aluminum lug on.

IIRC either I only ever had one of their kits, or used an Estes/Centuri lug on any others.

That incident was useful for future projects involving polypropelyne (flexible) plastics that refuse to be glued (like rocket powered frisbees). Where I'd use epoxy over a wide area to "glue" a mount in place, then easily pry it off, and then use contact cement to glue that pried-off epoxy right back where it had been on the polypropelyne plastic.

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I've used aluminum arrow shafts for 1/4" launch lugs the last 30 years or so.

They used to be a couple bucks for a 30+" shaft. They are probably a lot higher now. You might get some free ones from folks that bow hunt where they've damaged the fletching or bent a shaft. I don't think many people re-fletch arrows anymore.

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