Anybody have an old laserdisc player?

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lalligood

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For the past couple of months, I have been making spool rockets using CDs & BT-5, BT-20, & BT-50 tubing that fly on 13mm, 18mm, & 24mm motors, respectively. (See this thread for more information.) I am looking to upscale my design for use with 29mm & possibly even 38mm motors. My problem is this: A standard CD quite likely cannot handle the forces from the thrust of these larger motors. I need something with a larger diameter (greater surface area) but still has similar rigid yet flexible characteristics of a standard CD-ROM.

Someone from my club suggested using laserdiscs. IIRC, laserdiscs are the same size as standard LP vinyl records but what I can't remember is how thick and/or flexible they are. Does anyone have one of these (seemingly) ancient pieces of technology handy & that wouldn't mind assessing their potential use for my purpose?

eBay has proved to be a fairly abundant source for relatively inexpensive laserdisc movies but I don't want to go through the hassle of getting a couple unless I know they'll work.

Thanks for your help!
 

prowlerguy

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Laser discs are very thick and very heavy. I don't think that anything but an HPR will launch a spool rocket made from them, but they are extremely rigid so I think they will do what you want. However, Laserdisks also came in an 8" variety (about the same as a 45) that might be acceptable. Some titles I remember are a Tina Turner "Private Dancer" and the "We are the World" disc. That might be a better choice than the full size disc for an MPR engine. Hope this helps.
 

lalligood

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prowlerguy,

Thanks! That is *exactly* what I was looking to hear. And an extra big thanks for mentioning the smaller (8") discs--I'll definitely be on the lookout for those. I recently got my hands on a couple of mini-CDs (just under 3" dia.) that had promotional material for one of the Matrix films. My design with standard CDs & 18mm MMT on a C6-5 gets about 250' on a good day. With the smaller CDs (less than half the surface area)& same motor, I'd bet I'm getting twice that height!

Thanks again for the information!
 

Stymye

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Lalli
I have seen laser discs at the local "second hand " music shops

try browsing a couple of your local shops ,you may get a good deal on a pair ,

btw thats how I buy most of my cd's
(so I can spend more on rockets)
 

lalligood

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I called around to a few local used CD shops in town...no luck :( On eBay however, I stumbled upon a seller who happens to live on the far side of town from me with almost a dozen laserdiscs up for bid! Better yet, most of the auctions ended last night & I was the winner of 4 of the auctions :D Now I need to get my hands on some MMT tubing...
 

eugenefl

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Lance, ever thought of cutting some discs out of thin lightweight ply? I don't know if it's a specific diameter you're going for, but why not cut some out? I suppose the element of flying recycled parts might be lost, but I figure that'd save you a buck or two.
 

lalligood

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Originally posted by eugenefl
Lance, ever thought of cutting some discs out of thin lightweight ply? I don't know if it's a specific diameter you're going for, but why not cut some out? I suppose the element of flying recycled parts might be lost, but I figure that'd save you a buck or two.
eugenefl,
Yeah, you might be right... I've certainly got something for those shiny, relflective plastic discs ;) And I do have the tools to venture down the path of lightweight ply, but the one thing I really like about the CDs & (hopefully) laserdiscs is that they are extremely resilient under stress. They respond well & gently flex under pressure then bounce back into shape. Wood would probably work but then I'd have to potentially develop a recovery system to keep the wood from sustaining too much damage on impact. Plus the plastic discs with their metallic layer A) require no finishing/painting & B) are ultra-easy to track/locate for recovery.

IMO, cost wasn't TOO bad for the laserdiscs...it's not like I was looking for any particular movie on them and/or cared much about their condition aside from being intact. I was able to buy 4 laserdiscs + shipping for ~$3.50 each. I'd guess that I probably could've gotten enough wood for 4 discs for the price of one laserdisc...

Tradeoffs!:D
 
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